How Much Is 25 Units of Tirzepatide? Understanding Dose, Cost, and Concentration

Reviewed by FormBlends Medical Team · Last updated September 5, 2026 · Sources rebuilt September 2026

Key Takeaways

• 25 units on a U-100 insulin syringe equals 2.5 mg of tirzepatide at the standard 10 mg/mL concentration, the most common starting dose
• The same 25 units equals 1.25 mg at 5 mg/mL or 5 mg at 20 mg/mL, which is why concentration matters more than unit count
• As of September 3, 2026 the FormBlends Compounded GLP-1 Price Index puts the median 28-day price of compounded tirzepatide at $299 at 2.5 mg per week (14 providers, range $149 to $470), roughly $75 per weekly dose; brand Zepbound self-pay through LillyDirect starts at $299 a month for 2.5 mg
• The "unit" measurement is borrowed from insulin syringes and has nothing to do with tirzepatide potency or activity

The short answer

25 units of tirzepatide on a U-100 insulin syringe represents 2.5 mg of medication when your vial is at 10 mg/mL concentration. This is the standard starting dose for tirzepatide therapy. The same 25-unit draw delivers different milligram amounts at other concentrations. By the Price Index median, compounded tirzepatide at 2.5 mg costs about $299 per 28 days, about the same as the $299 LillyDirect self-pay price for brand Zepbound 2.5 mg (September 2026).

To get the units for your own vial, use the tirzepatide dosage calculator. Enter the vial size, the water you add and your dose; it returns the draw in units and millilitres and shows which water volume lands your dose on a printed mark.

Table of contents

1. What "25 units" actually measures
2. The concentration equation: why 25 units isn't always 2.5 mg
3. Complete dose conversion table for all common concentrations
4. Cost breakdown: what you pay for 25 units of tirzepatide
5. How to verify you're drawing the right milligram dose
6. The three-question concentration check before every injection
7. What most articles get wrong about tirzepatide units
8. When 25 units is the wrong dose for your prescription
9. Brand-name vs. compounded: the same dose, different economics
10. Storage impact on cost-per-dose
11. What 25 units costs today
12. Brand formats that do not use units
13. FAQ
14. Sources

What "25 units" actually measures

When pharmacies, providers, or online guides reference "25 units of tirzepatide," they're describing a volume measurement on a U-100 insulin syringe, not a measurement of tirzepatide activity or potency.

A U-100 insulin syringe is calibrated so that 100 units equals 1 mL of liquid. Each unit marking represents 0.01 mL (one-hundredth of a milliliter). Therefore, 25 units equals 0.25 mL of whatever liquid you're drawing, whether that's insulin, tirzepatide, semaglutide, or sterile water.

The "U-100" designation comes from insulin: U-100 insulin contains 100 units of insulin activity per milliliter. Tirzepatide has no unit-based potency system. It's measured in milligrams only. The convention of using "units" for tirzepatide exists purely because U-100 insulin syringes are the cheapest, most widely available syringes with markings small enough for the tiny subcutaneous doses GLP-1 medications require.

What this means in practice: saying "I take 25 units of tirzepatide" tells you the volume you're injecting (0.25 mL) but reveals nothing about the actual milligram dose unless you also know the vial's concentration.

The concentration equation: why 25 units isn't always 2.5 mg

The milligram dose you receive from 25 units depends entirely on how many milligrams of tirzepatide are dissolved in each milliliter of solution. This is the concentration, expressed as mg/mL.

The formula is simple:

Milligrams delivered = (Units drawn ÷ 100) × Concentration in mg/mL

For 25 units:

• At 5 mg/mL: (25 ÷ 100) × 5 = 1.25 mg
• At 10 mg/mL: (25 ÷ 100) × 10 = 2.5 mg
• At 15 mg/mL: (25 ÷ 100) × 15 = 3.75 mg
• At 20 mg/mL: (25 ÷ 100) × 20 = 5 mg

The same 25-unit draw delivers a four-fold difference in actual medication between the lowest and highest common concentrations. This is why the first question when someone asks "how much tirzepatide should I draw" is always "what's your vial concentration?"

Compounding pharmacies choose concentration based on vial size, shelf-life considerations, and dose-range optimization. A pharmacy dispensing primarily 2.5 mg and 5 mg doses might use 10 mg/mL because the unit math stays clean (25 units and 50 units). A pharmacy optimizing for higher-dose patients (10 mg, 12.5 mg, 15 mg) might use 20 mg/mL to reduce injection volume.

A well-known error pattern: patients switching between compounding pharmacies assume "25 units" remains constant and don't re-check concentration on the new vial. A patient stable on 2.5 mg weekly at 10 mg/mL (25 units) switches to a pharmacy using 5 mg/mL and draws the same 25 units, now receiving only 1.25 mg. They report the medication "stopped working" when the actual issue is a 50% under-dose from concentration mismatch.

Complete dose conversion table for all common concentrations

This table covers every concentration you're likely to encounter from a U.S. compounding pharmacy and the six most common tirzepatide doses:

Concentration	2.5 mg	5 mg	7.5 mg	10 mg	12.5 mg	15 mg
5 mg/mL	50 units (0.50 mL)	100 units (1.00 mL)	150 units (1.50 mL)*	200 units (2.00 mL)*	250 units (2.50 mL)*	300 units (3.00 mL)*
10 mg/mL	25 units (0.25 mL)	50 units (0.50 mL)	75 units (0.75 mL)	100 units (1.00 mL)	125 units (1.25 mL)	150 units (1.50 mL)
12.5 mg/mL	20 units (0.20 mL)	40 units (0.40 mL)	60 units (0.60 mL)	80 units (0.80 mL)	100 units (1.00 mL)	120 units (1.20 mL)
15 mg/mL	17 units (0.17 mL)	33 units (0.33 mL)	50 units (0.50 mL)	67 units (0.67 mL)	83 units (0.83 mL)	100 units (1.00 mL)
20 mg/mL	12.5 units (0.125 mL)	25 units (0.25 mL)	37.5 units (0.375 mL)	50 units (0.50 mL)	62.5 units (0.625 mL)	75 units (0.75 mL)
25 mg/mL	10 units (0.10 mL)	20 units (0.20 mL)	30 units (0.30 mL)	40 units (0.40 mL)	50 units (0.50 mL)	60 units (0.60 mL)

*Asterisks indicate doses that exceed the typical 1 mL maximum for comfortable subcutaneous injection. Most providers avoid prescribing these combinations.

The 25-unit row is bolded at 10 mg/mL because this is the single most common concentration-dose pairing for patients starting tirzepatide therapy.

A few patterns worth noting:

10 mg/mL is the industry standard because every milligram corresponds to exactly 10 units, making mental math trivial. Need 7.5 mg? That's 75 units. Need 12.5 mg? That's 125 units.

15 mg/mL creates fractional unit counts (17 units, 33 units, 83 units) that are harder to draw accurately on syringes with 1-unit increment markings. Most compounding pharmacies avoid this concentration unless vial-size constraints force it.

25 mg/mL is the highest concentration in this table. At that strength a 2.5 mg dose is only 10 units, and reading small unit markings accurately requires good vision and lighting. Correction, September 2026: an earlier version called 25 mg/mL the practical upper limit and cited precipitation risk; that claim was unsourced and has been removed.

5 mg/mL is used when injection volume isn't a concern and the pharmacy wants to maximize vial shelf-life or simplify handling. The trade-off is larger injection volumes (50 units for 2.5 mg means 0.5 mL, double the volume of the 10 mg/mL equivalent).

Cost breakdown: what you pay for 25 units of tirzepatide

The cost of 25 units of tirzepatide depends on whether you're using brand-name Mounjaro or Zepbound, or compounded tirzepatide from a licensed pharmacy.

Brand-name tirzepatide (Mounjaro, Zepbound)

Brand-name tirzepatide comes in three formats per the Zepbound prescribing information (revised August 2026): a single-dose pre-filled pen, a single-dose vial (both 2.5 to 15 mg in 0.5 mL), and a multi-dose KwikPen containing 10 mg per 2.4 mL that delivers four doses. Only the single-dose vial is drawn with a syringe, and it is a fixed 0.5 mL.

Retail price: GoodRx lists Mounjaro at as low as $1,086.78 for a 28-day carton of four pens against an average retail price of $1,348.16 (seen September 5, 2026). Correction, September 2026: the earlier '$1,069.08 per pen' on this page was the old per-carton list price misdescribed as a per-pen price. Zepbound savings card (commercial insurance that covers Zepbound): $25 a month, capped at $100 per 1-month fill and $1,300 per calendar year, 13 fills, card expires December 31, 2026. Commercial insurance that does not cover Zepbound: $499 for a 1-month single-dose pen fill, or $299 for the 2.5 mg KwikPen. LillyDirect self-pay: $299 (2.5 mg), $399 (5 mg), $449 (7.5 to 15 mg) when refilled within 45 days, otherwise $499 to $699. Medicare: the Medicare GLP-1 Bridge caps the Zepbound KwikPen at $50 a month from July 1, 2026 to December 31, 2027 with prior authorization. Medicaid: excluded from the card; coverage varies by state.

The pen delivers a fixed 2.5 mg dose. There's no "unit" measurement because you don't draw the dose yourself.

Compounded tirzepatide

Compounded tirzepatide is dispensed in multi-dose vials. Cost is typically quoted per vial or per milligram, not per unit.

What compounded tirzepatide costs, from the Price Index (as of September 3, 2026):

• Month 1 at 2.5 mg per week: median $299 per 28 days across 14 providers (range $149 to $470), about $75 per weekly dose
• Month 4 at 5 mg per week: median $299 per 28 days across 11 providers (range $179 to $627)

Correction, September 2026: an earlier version listed 30, 50 and 100 mg vial prices and per-dose costs of $12 to $30. Those figures were unsourced, and a 100 mg vial used over 40 weeks is incompatible with any beyond-use date; they have been removed. The Index prices are 28-day, all-in cash prices for a new self-pay patient; see the Compounded GLP-1 Price Index.

Concentration changes how many units you draw, not what the pharmacy charges per month.

At the starting dose, compounded and brand self-pay now cost about the same: the Price Index median of $299 per 28 days versus $299 for Zepbound 2.5 mg through LillyDirect. The gap opens at higher doses, where LillyDirect charges $399 (5 mg) and $449 (7.5 to 15 mg with a refill within 45 days) while the Index median at 5 mg stays at $299. Correction, September 2026: an earlier version said compounded was 95 to 98 percent cheaper; that was computed from wrong inputs and has been removed.

Insurance coverage: compounded tirzepatide is not covered by insurance. All costs are out-of-pocket. Some HSA and FSA plans allow reimbursement if prescribed for a covered indication (type 2 diabetes, obesity with BMI ≥30 or ≥27 with comorbidity).

How to verify you're drawing the right milligram dose

Before every injection, complete this three-step verification:

Step 1: Read the vial label concentration

The concentration appears on the vial label in one of these formats:

• "Tirzepatide 10 mg/mL"
• "Tirzepatide Injection 100 mg / 10 mL" (divide 100 by 10 = 10 mg/mL)
• "Tirzepatide for Injection, 50 mg per 5 mL" (divide 50 by 5 = 10 mg/mL)

If the label shows only total milligrams ("Tirzepatide 30 mg") without volume, the concentration is in the pharmacy's dispensing instructions, the patient information sheet, or the prescription label on the box. Call the pharmacy if you cannot locate it.

Step 2: Calculate the unit count for your prescribed milligram dose

Use this formula:

Units to draw = (Prescribed mg dose ÷ Concentration in mg/mL) × 100

For a 2.5 mg dose at 10 mg/mL: (2.5 ÷ 10) × 100 = 25 units

For a 2.5 mg dose at 5 mg/mL: (2.5 ÷ 5) × 100 = 50 units

For a 2.5 mg dose at 20 mg/mL: (2.5 ÷ 20) × 100 = 12.5 units

Write this unit count on the vial box in permanent marker. You should never have to recalculate for the same vial.

Step 3: Confirm the syringe type

Use only U-100 insulin syringes. The barrel must be marked "U-100." U-500 insulin syringes exist (for concentrated insulin) and are marked in U-500 insulin units, not in 0.01 mL steps. A U-500 syringe is scaled for insulin five times as concentrated, so the '25' mark on it holds 0.05 mL, one fifth of the volume you intend. Correction, September 2026: an earlier version described this as a five-fold overdose; the direction was inverted. Either way, never use a U-500 syringe for tirzepatide.

Common U-100 syringe sizes:

• 0.3 mL barrel (30 units max): marked in 1-unit increments, some models have half-unit marks
• 0.5 mL barrel (50 units max): marked in 1-unit increments
• 1 mL barrel (100 units max): marked in 2-unit increments along the barrel

For a 25-unit draw, any of these work. The 0.3 mL and 0.5 mL barrels are easier to read because the unit markings are more spread out.

The three-question concentration check before every injection

The FormBlends Pre-Injection Concentration Protocol is a three-question checklist designed to catch the most common dosing errors before they happen. Answer all three before drawing any dose.

Question 1: Is this the same vial I used last week?

If yes, proceed. If no (new vial, new pharmacy, or first dose), complete questions 2 and 3.

Question 2: What is the concentration printed on this vial's label?

Read it aloud. Write it down. Compare it to your last vial if you have the old box. Concentration changes between refills are a recognized cause of dose errors. FDA reports receiving adverse events, some requiring hospitalization, related to dosing errors with compounded injectable GLP-1 products, including patients measuring incorrect doses (FDA, content current September 1, 2026). Correction, September 2026: an earlier version cited Nguyen et al., Journal of Managed Care Pharmacy 2025; that paper does not exist and has been removed.

Question 3: Does the unit count I'm about to draw match the calculation for this concentration?

Recalculate using the formula in the section above, or reference the conversion table. If your prescribed dose is 2.5 mg and your vial is 10 mg/mL, you should be drawing 25 units. If the number doesn't match, stop and contact your provider or pharmacy before injecting.

What most articles get wrong about tirzepatide units

The most common error in published content about tirzepatide dosing is the claim that "25 units equals 2.5 mg" without the critical qualifier "at 10 mg/mL concentration."

Correction, September 2026: an earlier version of this section cited a 2025 content audit (Chen et al., Health Communication Research) of the top 20 Google results. That study does not exist and the paragraph has been removed. The error it described is easy to see for yourself: many pages state a fixed unit-to-milligram conversion without naming a concentration.

This error propagates because most patients starting tirzepatide receive 10 mg/mL vials, so "25 units = 2.5 mg" happens to be correct for the majority. The problem surfaces when patients switch pharmacies, titrate to higher doses that force a concentration change, or receive reconstituted vials where the final concentration depends on how much bacteriostatic water was added.

The second most common error is conflating "units" with a measure of tirzepatide potency, similar to how insulin units measure biological activity. Tirzepatide has no unit-based potency system. The peptide's activity is measured in milligrams only. A "unit" in this context is purely a volume marking on a syringe barrel, with no pharmacological meaning.

The third error is recommending that patients "round to the nearest unit" when a calculated dose falls between markings (for example, 12.5 units when the syringe only has 1-unit increments). Rounding 12.5 units down to 12 or up to 13 changes the dose by 4% at 12.5 mg concentration. For most patients this is clinically irrelevant, but the correct guidance is to round down (underdose is safer than overdose for GLP-1 medications) or to request a syringe with half-unit markings if precision matters.

When 25 units is the wrong dose for your prescription

Drawing 25 units is correct only if your prescribed milligram dose and vial concentration align to make 25 units the right volume. Here are the scenarios where 25 units would be incorrect:

Scenario 1: Your prescription says 5 mg, and your vial is 10 mg/mL

You should draw 50 units, not 25. Drawing 25 units delivers only 2.5 mg, half the prescribed dose.

Scenario 2: Your prescription says 2.5 mg, and your vial is 5 mg/mL

You should draw 50 units. Drawing 25 units delivers only 1.25 mg.

Scenario 3: Your prescription says 2.5 mg, and your vial is 20 mg/mL

You should draw 12.5 units. Drawing 25 units delivers 5 mg, double the prescribed dose.

Scenario 4: You reconstituted a powder vial and didn't follow the exact water volume in the instructions

If the instructions said "add 2 mL bacteriostatic water to the 30 mg vial" and you added 3 mL, your final concentration is 10 mg/mL instead of 15 mg/mL. The unit count for every dose changes. See our tirzepatide reconstitution guide for the full protocol.

Scenario 5: Your provider changed your dose mid-titration

If you started at 2.5 mg (25 units at 10 mg/mL) and your provider increased you to 5 mg, you now draw 50 units from the same vial. The unit count doubles even though the vial hasn't changed.

The safest approach: never memorize a unit count. Recalculate every time your dose changes or you receive a new vial.

Brand-name vs. compounded: the same dose, different economics

Both brand-name tirzepatide (Mounjaro for diabetes, Zepbound for weight loss) and compounded tirzepatide contain the same active peptide. The 2.5 mg starting dose is identical in milligram content. The differences are in formulation, delivery device, regulatory status, and cost.

Factor	Brand-name (Mounjaro/Zepbound)	Compounded tirzepatide
Active ingredient	Tirzepatide peptide	Tirzepatide peptide (same amino acid sequence)
FDA approval	Yes (Mounjaro May 2022; Zepbound November 2023)	No (compounded under 503A or 503B exemptions)
Delivery device	Single-dose pen, single-dose vial, or multi-dose KwikPen (10 mg per 2.4 mL, four doses)	Multi-dose vial, patient draws dose with syringe
2.5 mg dose cost (September 2026)	$25 with the savings card if covered; $499 (pen) or $299 (KwikPen) if not covered; $299 LillyDirect self-pay; $50 Medicare GLP-1 Bridge (KwikPen)	Price Index median $299 per 28 days (September 3, 2026)
Insurance coverage	Often covered for diabetes; weight-loss coverage varies by plan; Medicare GLP-1 Bridge $50 a month for the Zepbound KwikPen, July 1, 2026 to December 31, 2027	Not covered
Dose flexibility	Fixed doses only (2.5, 5, 7.5, 10, 12.5, 15 mg)	Prescriber-determined
Excipients	Proprietary stabilizers, buffers	Varies by pharmacy (some add B12, L-carnitine, or other peptides)
Sterility assurance	FDA-regulated manufacturing	State board of pharmacy oversight, USP 797 standards

The clinical effect of 2.5 mg is the same whether delivered by pen or vial, assuming proper storage and handling. The SURMOUNT-1 trial (Jastreboff et al., NEJM 2022) used brand-name tirzepatide and reported mean weight change of -15.0 percent at 5 mg, -19.5 percent at 10 mg and -20.9 percent at 15 mg versus -3.1 percent with placebo at 72 weeks. Correction, September 2026: an earlier version gave 15 percent for the 15 mg dose (that was the 5 mg result) and cited a 2025 retrospective cohort of compounded patients at 14.2 percent; the cohort could not be located and has been removed. No controlled trial of compounded tirzepatide exists.

The economic difference is structural. Eli Lilly's list price for Mounjaro reflects R&D cost recovery, FDA approval expenses, and patent-protected market exclusivity. Compounding pharmacies operate under a different regulatory framework (FDA's 503A and 503B provisions) that allows them to prepare patient-specific formulations without the same approval process, at substantially lower cost.

Storage impact on cost-per-dose

Tirzepatide is a peptide and degrades when exposed to heat, light, or temperature cycling. Improper storage doesn't just reduce efficacy; it increases cost-per-dose because you're paying for medication that's partially or fully inactive.

Refrigeration requirements:

• Unopened vials: 36-46°F (2-8°C). Store in the main refrigerator compartment, not the door (temperature fluctuates) or the back wall (risk of freezing).
• After first puncture: same temperature range. The pharmacy label sets the beyond-use date under USP General Chapter 797; the common multi-dose vial practice is 28 days after first puncture unless the label says otherwise.

Freezing destroys tirzepatide. If a vial freezes (even partially), the peptide aggregates and loses activity. Thawing doesn't reverse the damage. A frozen vial must be discarded.

Room temperature exposure: brand-name Mounjaro pens can be kept at room temperature (up to 86°F) for 21 days. For compounded tirzepatide, follow the pharmacy label; no general room-temperature figure applies. If you're traveling, use an insulated medication cooler with a gel pack (not direct ice contact).

Light exposure: tirzepatide degrades under UV light. Store vials in the original box or wrap in aluminum foil if the box is discarded.

Correction, September 2026: this section previously included a worked example in which a vial lost 22 percent of its potency and the patient drew 32 units instead of 25 to compensate. The potency figure was hypothetical, and adjusting your own dose for suspected degradation is unsafe; the example has been removed. If you suspect a vial has degraded, contact the pharmacy.

Proper storage isn't optional. It's cost control.

The decision tree for "how much should I draw?"

Use this branching decision flow every time you prepare an injection:

START: Do you know your prescribed dose in milligrams?

• Yes → Proceed to next question
• No → Check your prescription, patient portal, or provider's written instructions. Do not guess. If you can't find it, contact your provider before drawing.

Do you know your vial's concentration in mg/mL?

• Yes → Proceed to calculation
• No → Check the vial label, the box, or the pharmacy's dispensing instructions. If concentration isn't listed anywhere, call the pharmacy. Do not draw.

Calculate: (Prescribed mg dose ÷ Concentration) × 100 = Units to draw

Example: (2.5 mg ÷ 10 mg/mL) × 100 = 25 units

Is the calculated unit count a whole number or half-unit increment?

• Yes → Draw that amount
• No (fractional unit like 12.3 or 17.7) → Round down to the nearest marking on your syringe. For a 1-unit increment syringe, round 12.3 down to 12. For a 0.5-unit increment syringe, round 12.3 down to 12.

Does your syringe have markings small enough to draw the calculated dose?

• Yes → Proceed with injection
• No (dose is below 10 units on a 1 mL syringe with 2-unit increments) → Request a 0.3 mL syringe with finer markings from your pharmacy

After drawing, does the liquid in the syringe look clear and colorless (or faint yellow if B12 is added)?

• Yes → Proceed
• No (cloudy, particulate, or discolored in an unexpected way) → Do not inject. Contact the pharmacy.

When you should not rely on unit-based dosing

Unit-based dosing using a U-100 syringe is the standard for compounded tirzepatide, but there are situations where this method introduces unacceptable error risk:

Situation 1: Doses below 10 units on a 1 mL syringe

A 1 mL U-100 syringe has 2-unit increment markings below the 50-unit line. Drawing 8 units (for example, 2 mg at 25 mg/mL concentration) requires estimating between the 8-unit and 10-unit marks. The error margin is too high. Use a 0.3 mL syringe with 1-unit or 0.5-unit increments instead.

Situation 2: Doses requiring half-unit precision on a syringe without half-unit marks

If your dose calculates to 12.5 units and your syringe only has 1-unit increments, you're forced to round. Rounding down to 12 units under-doses by 4%. Rounding up to 13 over-doses by 4%. For most patients this is clinically irrelevant, but if you're titrating slowly or have a history of dose-sensitive side effects, request a syringe with half-unit markings.

Situation 3: Mixing multiple peptides in one syringe

Some compounding pharmacies offer "blended" formulations (tirzepatide + semaglutide, or tirzepatide + L-carnitine + other peptides). If you're drawing from multiple vials and combining in one syringe, unit-based dosing becomes ambiguous. You need to calculate the milliliter volume for each component separately, then verify the total volume fits in the syringe barrel.

Situation 4: Reconstituted vials where you're not confident in the final concentration

If you reconstituted a powder vial and didn't measure the bacteriostatic water precisely (for example, you eyeballed "about 2 mL" instead of using a syringe to measure exactly 2.00 mL), your final concentration is unknown. Drawing "25 units" could deliver anywhere from 2 mg to 3 mg depending on how much water you actually added. In this case, discard the vial and reconstitute a new one following exact measurements.

The theme across all four situations: unit-based dosing is a shorthand that works only when concentration is known and syringe precision matches dose requirements. When either condition fails, revert to milliliter-based calculations and verify with a pharmacist.

What 25 units costs today (September 2026)

Twenty-five units at 10 mg/mL is 2.5 mg, the starting dose, so the question of cost is really 'what does a month at 2.5 mg cost.' Here is the dated answer.

Route	Monthly price	Source, date seen
Compounded tirzepatide, month 1 at 2.5 mg per week	Median $299 per 28 days (14 providers, $149 to $470); month 4 at 5 mg median $299 (11 providers, $179 to $627)	FormBlends Compounded GLP-1 Price Index, September 3, 2026
Zepbound, commercial insurance covers it, savings card	$25 (card pays up to $100 per 1-month fill, $1,300 per year, 13 fills; expires December 31, 2026)	zepbound.lilly.com, September 5, 2026
Zepbound, commercial insurance does not cover it, savings card	$499 for a 1-month single-dose pen fill; $299 for the 2.5 mg KwikPen	zepbound.lilly.com, September 5, 2026
Zepbound, LillyDirect self-pay (vial or KwikPen)	$299 (2.5 mg), $399 (5 mg), $449 (7.5 to 15 mg) with a refill within 45 days; otherwise $499 (7.5 mg) and $699 (10 to 15 mg)	lilly.com/lillydirect, September 5, 2026
Zepbound KwikPen, Medicare GLP-1 Bridge	$50 a month with prior authorization, July 1, 2026 to December 31, 2027	healthinsurance.org; zepbound.lilly.com
Mounjaro, retail without coverage	As low as $1,086.78 for a 28-day carton (average retail $1,348.16)	GoodRx, September 5, 2026

FormBlends does not state its own product price in this article; the Index is the sourced comparison.

Brand formats that do not use units

Unit counting only applies to a vial you draw from yourself. The Zepbound prescribing information (revised August 2026) lists three brand formats: a single-dose pre-filled pen and a single-dose vial, each holding a fixed dose of 2.5 to 15 mg in 0.5 mL, and a multi-dose KwikPen holding 10 mg in 2.4 mL that delivers four weekly doses by dialing, not by syringe. Storage from the same label: refrigerate at 2 to 8°C; single-dose pens and vials may stay unrefrigerated at up to 30°C (86°F) for a total of 21 days; the KwikPen and multi-dose vial are discarded 30 days after first use or after the fourth dose. Switching from any of these to a compounded vial means recalculating units from the vial's labeled concentration.

FAQ

How much is 25 units of tirzepatide in milligrams?

25 units equals 2.5 mg at 10 mg/mL concentration, 1.25 mg at 5 mg/mL, 3.75 mg at 15 mg/mL, or 5 mg at 20 mg/mL. The milligram amount depends entirely on your vial's concentration. Check the vial label before every injection.

How much does 25 units of tirzepatide cost?

By the FormBlends Compounded GLP-1 Price Index (September 3, 2026), compounded tirzepatide at 2.5 mg per week has a median price of $299 per 28 days, about $75 per weekly dose. Brand Zepbound 2.5 mg is $299 a month self-pay through LillyDirect, $25 with the savings card if your commercial plan covers it, and $499 (pen) or $299 (KwikPen) if it does not.

Is 25 units the same as 0.25 mL?

Yes. On a U-100 insulin syringe, 25 units always equals 0.25 mL of liquid volume. The milligram dose delivered by that 0.25 mL depends on the medication's concentration.

Can I use a U-500 syringe to draw tirzepatide?

No. U-500 syringes are scaled for insulin five times as concentrated as U-100, so their markings do not correspond to 0.01 mL. The '25' mark on a U-500 syringe holds only 0.05 mL, one fifth of the intended volume. Correction, September 2026: an earlier version called this a five-fold overdose; the direction was inverted. Use only U-100 syringes.

What if my dose is 2.5 mg but my vial is 5 mg/mL?

You draw 50 units, not 25. At 5 mg/mL concentration, 50 units (0.5 mL) delivers 2.5 mg of tirzepatide. Use the formula: (2.5 mg ÷ 5 mg/mL) × 100 = 50 units.

How do I know if I drew the right amount?

After drawing, hold the syringe at eye level. The leading edge of the black rubber plunger (the end closest to the needle) should align exactly with the unit marking that matches your calculated dose. If you calculated 25 units, the plunger edge should sit on the 25-unit line.

What happens if I accidentally draw 50 units instead of 25?

If you haven't injected yet, push the excess back into the vial and re-draw 25 units. If you've already injected, you've received double your prescribed dose. Monitor for nausea, vomiting, and abdominal pain. Most patients tolerate a one-time double dose without serious effects, but contact your provider if symptoms are severe or last longer than 24 hours.

Can I split 25 units into two injections?

Tirzepatide's half-life is approximately 5 days, and it's designed for once-weekly dosing. Splitting into two injections per week isn't standard protocol. Some providers allow split dosing during initial titration if side effects are intolerable, but this should be a clinical decision, not self-directed.

Why does my pharmacy use 10 mg/mL instead of 5 mg/mL?

10 mg/mL is the most common concentration because the math is simpler (every 1 mg = 10 units) and injection volumes stay small across the full dose range. 5 mg/mL is used when a pharmacy wants to extend shelf life or reduce concentration-related precipitation risk, but it requires larger injection volumes.

How long does a 30 mg vial last at 2.5 mg per week?

A 30 mg vial contains 12 doses of 2.5 mg. In practice the beyond-use date on the pharmacy label, set under USP General Chapter 797, comes first: most refrigerated compounded sterile preparations are limited to 10 to 60 days, and multi-dose vials are commonly discarded 28 days after first puncture. Check your label.

Does the unit count change if I switch from Mounjaro to compounded tirzepatide?

Mounjaro pens deliver a fixed dose and don't use unit measurements. If you switch to compounded tirzepatide, you'll need to calculate the unit count based on your vial's concentration. A 2.5 mg Mounjaro pen delivers the same milligram dose as 25 units of compounded tirzepatide at 10 mg/mL.

What if my calculated dose is 12.5 units and my syringe only has 1-unit markings?

Draw to the line halfway between 12 and 13 if you can estimate it visually. If you can't estimate accurately, round down to 12 units (slight underdose is safer than overdose). Better option: request a syringe with half-unit markings from your pharmacy.

Is compounded tirzepatide still cheaper than Zepbound in 2026?

At the 2.5 mg starting dose, not by much. The FormBlends Compounded GLP-1 Price Index median for month 1 at 2.5 mg per week was $299 per 28 days on September 3, 2026, and LillyDirect sells Zepbound 2.5 mg for $299 a month. At 5 mg the Index median stays at $299 while LillyDirect charges $399, and at 7.5 to 15 mg LillyDirect is $449 with a refill within 45 days. Covered patients with the savings card pay $25.

Does Medicare cover tirzepatide for weight loss in 2026?

Through the Medicare GLP-1 Bridge, yes for the Zepbound KwikPen: $50 a month with prior authorization from July 1, 2026 to December 31, 2027, outside the $2,100 Part D out-of-pocket cap (healthinsurance.org; zepbound.lilly.com, seen September 5, 2026). The Zepbound savings card still excludes Medicare enrollees. Compounded tirzepatide is not covered by Medicare or any insurer.

Related guides

• Is 50 Units of Semaglutide a Lot? Understanding Dose Context and Concentration
• How Much Does Compounded Tirzepatide Cost in 2026? A Dose-by-Dose Pricing Guide and Decision Framework
• Is 25 Units of Tirzepatide a Lot? Understanding Dose Context and Clinical Meaning
• Is 20 Units of Semaglutide Too Much? A Concentration-Specific Safety Breakdown
• How Much Is 20 Units of Semaglutide? A Concentration-Based Conversion Guide
• Semaglutide Syringe Dosage Conversion Chart: How Many Units for Every Dose at Every Concentration
• Tool: dosage calculator

Sources

1. Jastreboff AM et al. Tirzepatide Once Weekly for the Treatment of Obesity. New England Journal of Medicine. 2022.
2. Frias JP et al. Tirzepatide versus Semaglutide Once Weekly in Patients with Type 2 Diabetes. New England Journal of Medicine. 2021.
3. FormBlends. Compounded GLP-1 Price Index, weekly snapshot as of September 3, 2026 (USD per 28-day supply, all-in cash, new U.S. self-pay patient). https://formblends.com/feeds/glp1-prices.json
4. Eli Lilly. LillyDirect Zepbound self-pay pricing ($299, $399, $449 with refill within 45 days; regular $499 to $699), seen September 5, 2026. https://www.lilly.com/lillydirect/zepbound
5. Eli Lilly. Zepbound Savings Card terms (covered: $25, caps $100/$200/$300, $1,300 per year, 13 fills, expires December 31, 2026; not covered: $499 pen, $299 KwikPen), seen September 5, 2026. https://zepbound.lilly.com/coverage-savings
6. United States Pharmacopeia. USP Compounding Standards and Beyond-Use Dates fact sheet (revised General Chapters 795 and 797, published November 1, 2022; official November 1, 2023). https://www.mbp.ms.gov/sites/default/files/2023-03/USP_Compounding_BUD_Fact_Sheet.pdf
7. United States Pharmacopeia. General Chapter 1: Injections and Implanted Drug Products. 2023.
8. ISO 8537:2016. Sterile single-use syringes, with or without needle, for insulin. International Organization for Standardization. 2016.
9. U.S. Food and Drug Administration. FDA's concerns with unapproved GLP-1 drugs used for weight loss, content current September 1, 2026. https://www.fda.gov/drugs/drug-alerts-and-statements/fdas-concerns-unapproved-glp-1-drugs-used-weight-loss
10. Rosenstock J et al. Efficacy and safety of a novel dual GIP and GLP-1 receptor agonist tirzepatide in patients with type 2 diabetes (SURPASS-1). Lancet. 2021.
11. Ludvik B et al. Once-weekly tirzepatide versus once-daily insulin degludec as add-on to metformin with or without SGLT2 inhibitors in patients with type 2 diabetes (SURPASS-3). Lancet. 2021.
12. Del Prato S et al. Tirzepatide versus insulin glargine in type 2 diabetes and increased cardiovascular risk (SURPASS-4). Lancet. 2021.
13. Dahl D et al. Effect of Subcutaneous Tirzepatide vs Placebo Added to Titrated Insulin Glargine on Glycemic Control in Patients With Type 2 Diabetes (SURPASS-5). JAMA. 2022.
14. Garvey WT et al. Tirzepatide once weekly for the treatment of obesity in people with type 2 diabetes (SURMOUNT-2). Lancet. 2023.
15. GoodRx. Mounjaro prices (as low as $1,086.78 for a 28-day carton; average retail $1,348.16), seen September 5, 2026. https://www.goodrx.com/mounjaro
16. healthinsurance.org. Does health insurance cover drugs used for weight loss (Medicare GLP-1 Bridge: $50 a month, July 1, 2026 to December 31, 2027, Zepbound KwikPen, prior authorization). https://www.healthinsurance.org/faqs/does-health-insurance-cover-drugs-used-for-weight-loss-such-as-ozempic-wegovy-mounjaro-and-zepbound/
17. Eli Lilly and Company. Zepbound (tirzepatide) prescribing information, revised 08/2026. https://pi.lilly.com/us/zepbound-uspi.pdf
18. Jastreboff AM et al. Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1). New England Journal of Medicine. 2022;387:205-216. PubMed PMID 35658024.

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Platform Disclaimer. FormBlends is a digital health platform that connects patients with licensed providers and U.S.-based pharmacies. We do not manufacture, prescribe, or dispense medication directly. All clinical decisions are made by independent licensed providers.

Compounded Medication Notice. Compounded semaglutide and tirzepatide are not FDA-approved. They are prepared by a state-licensed compounding pharmacy in response to an individual prescription. Compounded medications have not undergone the same review process as FDA-approved drugs and are not interchangeable with brand-name products.

Results Disclaimer. Individual results vary. Weight-loss outcomes depend on diet, exercise, adherence, baseline weight, and individual response to treatment. Statements about average outcomes reference published clinical trial data, which may differ from real-world results.

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