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Key Takeaways
- 1 mg = 1,000 mcg, exactly. 2 mg = 2,000 mcg. 5,000 mcg = 5 mg. No rounding, no variables.
- A U-100 insulin syringe has 100 units per 1 mL; each unit line = 0.01 mL. Converting mcg to syringe units requires knowing your reconstitution concentration first.
- At a 2.5 mg/mL concentration, a 250 mcg dose = 0.10 mL = 10 units on a U-100 syringe.
- Most published peptide dose targets come from animal data or small open-label human reports, not large RCTs. The math is exact; the clinical targets are not.
- Purity varies widely across research peptide suppliers. An HPLC purity below 95% on the COA means a meaningful fraction of what you inject is not the intended compound.
What Is a Peptide Dosing Chart and Why Does the Math Matter?
Table of Contents
- How do I convert mg to mcg and mcg to mg?
- How do I convert mcg to units on an insulin syringe?
- How does reconstitution volume change every dose I draw?
- Peptide dosing chart: common vials and concentrations
- Evidence ledger: how confident should I be in published dose targets?
- What most dosing pages get wrong (bioavailability and purity reality)
- Why does reconstituted peptide degrade and how fast?
- Peptide vs. approved drug: honest head-to-head
- How to read a vial label and COA before you dose
- Frequently Asked Questions
- Sources
How Do I Convert mg to mcg and mcg to mg?
The metric prefix "milli" is 10-3 and "micro" is 10-6, both relative to a gram. The ratio between them is exactly 1,000 and this never changes regardless of what substance you are measuring.
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Try the BMI Calculator →| Starting value | Operation | Result |
|---|---|---|
| 1 mg | x 1,000 | 1,000 mcg |
| 2 mg | x 1,000 | 2,000 mcg |
| 5 mg | x 1,000 | 5,000 mcg |
| 0.5 mg | x 1,000 | 500 mcg |
| 250 mcg | / 1,000 | 0.25 mg |
| 2,000 mcg | / 1,000 | 2 mg |
| 5,000 mcg | / 1,000 | 5 mg |
| 100 mcg | / 1,000 | 0.1 mg |
The conversion itself is exact and carries zero measurement uncertainty. The uncertainty in peptide dosing comes from downstream steps: concentration accuracy after reconstitution, syringe graduation resolution, and actual peptide purity in the vial.
How Do I Convert mcg to Units on an Insulin Syringe?
Insulin syringes labeled "U-100" are calibrated so that 1 mL equals 100 units. Each small graduation therefore represents 0.01 mL. The word "units" here describes a volume division on that specific syringe, not an international unit of biological activity.
Three-step conversion from mcg to syringe units:
- Confirm your reconstituted concentration in mcg/mL.
- Divide target dose (mcg) by concentration (mcg/mL) to get volume in mL.
- Multiply mL by 100 to read the number of unit lines on a U-100 syringe.
| Target dose | Concentration | Volume (mL) | U-100 syringe units |
|---|---|---|---|
| 100 mcg | 1,000 mcg/mL (1 mg/mL) | 0.10 mL | 10 units |
| 250 mcg | 2,500 mcg/mL (2.5 mg/mL) | 0.10 mL | 10 units |
| 500 mcg | 2,500 mcg/mL (2.5 mg/mL) | 0.20 mL | 20 units |
| 300 mcg | 1,000 mcg/mL (1 mg/mL) | 0.30 mL | 30 units |
| 500 mcg | 5,000 mcg/mL (5 mg/mL) | 0.10 mL | 10 units |
| 1,000 mcg | 2,000 mcg/mL (2 mg/mL) | 0.50 mL | 50 units |
| 2,000 mcg | 5,000 mcg/mL (5 mg/mL) | 0.40 mL | 40 units |
How Does Reconstitution Volume Change Every Dose I Draw?
Reconstitution volume directly sets your concentration. Adding 1 mL of bacteriostatic water (BAC water) to a 5 mg vial gives 5 mg/mL (5,000 mcg/mL). Adding 2 mL to the same vial gives 2.5 mg/mL (2,500 mcg/mL). If you intend 2.5 mg/mL and accidentally add 1 mL instead of 2 mL, every dose drawn at "10 units" delivers twice the intended mass.
| Vial size | BAC water added | Resulting concentration | 250 mcg dose = how many units? |
|---|---|---|---|
| 2 mg (2,000 mcg) | 1 mL | 2,000 mcg/mL | 12.5 units |
| 2 mg (2,000 mcg) | 2 mL | 1,000 mcg/mL | 25 units |
| 5 mg (5,000 mcg) | 1 mL | 5,000 mcg/mL | 5 units |
| 5 mg (5,000 mcg) | 2 mL | 2,500 mcg/mL | 10 units |
| 5 mg (5,000 mcg) | 5 mL | 1,000 mcg/mL | 25 units |
| 10 mg (10,000 mcg) | 2 mL | 5,000 mcg/mL | 5 units |
| 10 mg (10,000 mcg) | 10 mL | 1,000 mcg/mL | 25 units |
Practical rule: Write the date reconstituted, the BAC water volume added, and the resulting concentration directly on the vial with a marker before capping. Do this before drawing the first dose, not after.
Peptide Dosing Chart: Common Research Peptides, Typical Dose Ranges and Syringe Math
The dose ranges below reflect ranges reported in published animal studies, small human pharmacokinetic reports, or compounding pharmacy protocols. They are not FDA-approved therapeutic doses. Confidence ratings are explained in the evidence ledger below.
| Peptide | Reported dose range | Common vial size | Suggested reconstitution | Concentration | Dose in U-100 units (mid-range example) |
|---|---|---|---|---|---|
| BPC-157 | 200-500 mcg/day (rodent-extrapolated) | 5 mg | 2 mL BAC water | 2,500 mcg/mL | 250 mcg = 10 units |
| TB-500 (Thymosin Beta-4 fragment) | 2-5 mg/week (case reports) | 5 mg | 2 mL BAC water | 2,500 mcg/mL | 2.5 mg = 100 units |
| CJC-1295 / Ipamorelin blend | 100-300 mcg each, per injection | 5 mg blend | 2 mL BAC water | 2,500 mcg/mL | 200 mcg = 8 units |
| PT-141 (Bremelanotide) | 1.75 mg (FDA-approved Vyleesi dose) | 1.75 mg pre-filled | Pre-mixed | 1.75 mg/0.3 mL = 5.83 mg/mL | N/A, fixed auto-injector |
| Sermorelin | 200-500 mcg nightly (compounded) | 6 mg or 9 mg | 3 mL BAC water | 2,000-3,000 mcg/mL | 300 mcg = 10-15 units |
| GHK-Cu (topical) | 0.5-2% w/v (topical studies) | Solution | N/A | 5-20 mg/mL (topical) | Not injected; topical only |
Evidence Ledger: How Confident Should You Be in Published Dose Targets?
The conversion math in this article is exact. The dose targets circulating in online peptide communities are not. This table grades the evidence behind common dose claims.
| Claim | Best evidence type | Effect direction | Confidence |
|---|---|---|---|
| 1 mg = 1,000 mcg (unit conversion) | SI definition (NIST) | Fixed, exact | High |
| U-100 syringe = 100 units/mL | USP device standard | Fixed, exact | High |
| BPC-157 promotes tendon healing (animal) | Multiple rat/rodent RCTs | Positive in animal models | Moderate (animal) |
| BPC-157 effective dose in humans | No published human RCT as of 2025 | Unknown | Very Low |
| Sermorelin increases IGF-1 in GH-deficient adults | Small human RCTs (e.g., Prakash and Goa, 1999, Drugs) | Positive, modest effect | Moderate |
| CJC-1295 extends GH pulse duration | Human PK study (Ionescu and Frohman, 2006, JCEM) | Positive, pharmacokinetic | Moderate (PK only) |
| PT-141 improves female sexual dysfunction | Phase 3 RCTs (FDA submission data) | Positive, statistically significant | High (approved indication) |
| GHK-Cu reduces wrinkle depth (topical) | Small industry-funded cosmetic trials | Modest positive | Low |
| Specific numeric dose targets for most research peptides | Rodent allometric scaling or community extrapolation | Directionally uncertain | Very Low |
Allometric scaling from rodent to human is not linear. Body surface area scaling factors are commonly applied in pharmacology, but peptide receptor density, plasma half-life, and first-pass kinetics differ substantially across species. A dose that produces a defined effect in a rat does not map reliably to humans without dedicated human dose-finding trials.
What Most Dosing Pages Get Wrong: Bioavailability and Purity Reality
This is the section most peptide pages skip entirely. Two issues materially change what your calculated dose actually delivers.
Subcutaneous bioavailability is not 100%
Insulin achieves roughly 55-77% subcutaneous bioavailability depending on site and formulation (data from pharmacokinetic reviews of insulin analogs, e.g., Heinemann and Richter, 1993, Clinical Pharmacokinetics). Peptides have variable and generally lower oral bioavailability; subcutaneous bioavailability for most research peptides has not been formally characterized in humans. Published animal subcutaneous bioavailability estimates for BPC-157 fragments exceed 90% in some rodent studies, but human data are absent. Any dose target assumes 100% delivery unless a bioavailability correction factor is specified, and most community protocols do not specify one.
Purity variation is a dosing multiplier
If a vial labeled "5 mg BPC-157" contains peptide at 85% HPLC purity, the actual peptide mass is closer to 4.25 mg. The remaining 15% is likely truncated sequences, synthesis byproducts, or residual protecting groups. At common dose ranges this difference is unlikely to cause acute harm, but it means your dose-response data is contaminated. Reputable suppliers provide HPLC and mass spectrometry COAs. Purity below 95% should prompt sourcing reconsideration. Many widely used research peptide vendors do not disclose purity data on their product pages.
Lyophilized weight vs. peptide content
The labeled vial weight often includes excipients added during lyophilization (commonly mannitol or acetic acid salts). A vial labeled "5 mg" may state "5 mg peptide content" or "5 mg total lyophilized cake." These are not the same value. Confirm with the COA whether the stated mass refers to peptide net weight or total lyophilate.
Why Does a Reconstituted Peptide Degrade and How Fast?
The chemistry behind refrigeration and BAC water rules is specific and worth understanding so you can evaluate edge cases yourself.
Deamidation: Asparagine (Asn) and glutamine (Gln) residues in peptide sequences undergo hydrolytic deamidation in aqueous solution. The rate accelerates with pH above 7, elevated temperature, and sequence-specific neighboring residues. Products are aspartate and isoaspartate variants with different receptor binding profiles. This is the dominant degradation pathway for many small peptides in solution.
Oxidation: Methionine and cysteine residues oxidize on contact with dissolved oxygen. This is why some peptides are shipped under argon and why repeated vial puncture gradually introduces oxygen. Each needle insertion is a small oxygen exposure event.
Aggregation: Freeze-thaw cycles promote intermolecular hydrogen bonding and hydrophobic collapse, producing aggregates that are immunogenic in theory and biologically inactive in practice. This is why single-use reconstitution is recommended for some peptides rather than partial-use refrigerated storage.
Bacteriostatic water (BAC water) vs. sterile water: BAC water contains 0.9% benzyl alcohol, which inhibits microbial growth and extends usable storage life compared to sterile water for injection. Sterile water without preservative should be used for single-dose reconstitution only. Using sterile water for a multi-week vial creates real contamination risk regardless of refrigeration.
Published stability windows for most research peptides are not in the public literature with formal kinetic data. A conservative working estimate used in compounding pharmacy contexts is 28 days refrigerated in BAC water, but this is not derived from published degradation kinetics for every peptide sequence. Some sequences are considerably less stable.
Honest Head-to-Head: Peptide vs. Approved Alternatives
| Use case | Research peptide option | Approved / established alternative | Evidence advantage | Practical advantage | Where peptide loses |
|---|---|---|---|---|---|
| GH axis stimulation | Sermorelin, CJC-1295/Ipamorelin | Recombinant human GH (somatropin) | Somatropin: decades of RCT data | Peptides: preserve pulsatile GH pattern, lower cost | Regulatory status, dose certainty, long-term safety data |
| Female sexual dysfunction | PT-141 (compounded) | Bremelanotide (Vyleesi, FDA-approved) | Vyleesi: Phase 3 RCT data | Compounded: may be lower cost | Compounded lacks FDA manufacturing oversight |
| Soft tissue healing | BPC-157 | PRP injections, NSAIDs, physical therapy | PRP: several human RCTs (mixed results); PT: strong evidence | BPC-157: mechanistic animal data is compelling | Zero human RCTs; no dose established; legal gray area |
| Skin anti-aging (topical) | GHK-Cu, Matrixyl peptides | Topical tretinoin (retinoic acid) | Tretinoin: multiple large RCTs (e.g., Griffiths et al. 1995, NEJM) | Peptides: better tolerability, no photosensitivity | Effect size substantially smaller than tretinoin; evidence base thin |
How to Read a Vial Label and COA Before You Dose
This is the operational checklist a skeptical clinician would run through before trusting any reconstituted peptide dose.
On the vial label, confirm:
- Peptide name and sequence identifier (not just a brand name). Cross-check the molecular weight against PubChem or a peptide database.
- Net peptide mass in mg, explicitly stated as peptide content (not total lyophilate weight).
- Lot number and expiry date for lyophilized storage (typically 12-24 months at -20 degrees C for most lyophilized peptides, though this varies).
- Storage conditions as stated by the manufacturer, not a general rule of thumb.
On the COA, verify:
- HPLC purity: expressed as area percentage. Above 98% is research-grade. Below 95% is a red flag.
- Mass spectrometry (MS) confirmation: the observed molecular weight should match the theoretical MW of the peptide within instrument error (typically within 1 Dalton for small peptides using MALDI or ESI-MS). A mismatch suggests wrong peptide, truncation, or modification.
- Endotoxin testing: LAL (limulus amebocyte lysate) test results matter for injectable peptides. Endotoxin limits for injectable drugs per USP are less than 0.2 EU/kg/hr. Many research peptide COAs omit this test entirely.
- Date of analysis: A COA dated two years before your purchase describes that lot on that date, not today.
Reconstitution verification step:
After adding BAC water, a properly reconstituted peptide solution should be clear and colorless to faintly opalescent. Cloudiness, particulate matter, or any color beyond pale yellow indicates precipitation or contamination and the vial should not be used.
Frequently Asked Questions
How do I convert mg to mcg for peptides?
Multiply milligrams by 1,000. 1 mg = 1,000 mcg. So 2 mg = 2,000 mcg and 5 mg = 5,000 mcg. This conversion is fixed and unit-independent of concentration.
What does 2 mg to mcg equal?
2 mg = 2,000 mcg. Multiply any milligram value by 1,000 to reach micrograms. This is a fixed metric conversion with no variables.
What does 5,000 mcg to mg equal?
5,000 mcg = 5 mg. Divide micrograms by 1,000 to reach milligrams. A 5 mg vial therefore contains 5,000 mcg of peptide.
How do I read a peptide dosing chart in units on an insulin syringe?
A standard U-100 insulin syringe holds 100 units per 1 mL. Each unit = 0.01 mL. To find units, divide your desired dose in mL by 0.01. Example: 0.25 mL = 25 units on the syringe.
What is a 2.5 mg/mL peptide solution?
A 2.5 mg/mL solution means each 1 mL of bacteriostatic water contains 2.5 mg (2,500 mcg) of peptide. To get 250 mcg you would draw 0.1 mL (10 units on a U-100 syringe).
How do I convert 1 mL to mg for a peptide?
1 mL alone tells you volume, not mass. You need the concentration. At 2 mg/mL, 1 mL = 2 mg. At 10 mg/mL, 1 mL = 10 mg. Always confirm reconstitution volume before drawing.
How do I calculate peptide dose in units from mcg?
Step 1: divide desired mcg by total mcg in vial to get the fraction of the vial. Step 2: multiply by total mL of reconstituted solution. Step 3: multiply by 100 to convert mL to U-100 syringe units.
What is the difference between mcg and units for peptides?
Mcg (micrograms) is a mass unit. Units on an insulin syringe are a volume measurement calibrated to 0.01 mL each for a U-100 syringe. They are not interchangeable without knowing concentration.
What happens if I add the wrong volume of water during reconstitution?
Adding more water than intended lowers concentration, so each unit drawn delivers less peptide. Adding less raises concentration and risks accidental overdose. Always record the exact mL added and recalculate before each dose.
How stable is a reconstituted peptide solution?
Stability varies by peptide. Most reconstituted peptides in bacteriostatic water refrigerated at 2-8 degrees Celsius are considered usable for roughly 2-4 weeks, though published degradation kinetics differ by sequence. Freeze-thaw cycles accelerate aggregation.
Are peptide dosing protocols supported by human clinical trials?
Most widely circulated peptide dosing protocols originate from animal studies or small open-label human reports, not large randomized controlled trials. The conversion math is exact; the clinical dose targets carry low-to-moderate evidence at best.
How do I verify a peptide vial contains what the label claims?
Request a certificate of analysis (COA) showing HPLC purity (target above 98%) and mass spectrometry confirmation of molecular weight. Cross-check the peptide molecular weight against published databases such as PubChem.
Sources
- National Institute of Standards and Technology (NIST). SI base units and metric prefixes.
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