Key Takeaway
Peptide prescriptions use different measurement units depending on the peptide and the provider. Understanding peptide dose conversion between milligrams (mg), micrograms (mcg), and international units (IU) prevents dosing errors and keeps your protocol safe.
Peptide prescriptions use different measurement units depending on the peptide and the provider. Understanding peptide dose conversion between milligrams (mg), micrograms (mcg), and international units (IU) prevents dosing errors and keeps your protocol safe. If you've ever stared at your prescription and felt confused by the numbers, this guide is for you.
Key Takeaways: - The Three Units You'll See in Peptide Dosing - Quick Reference Conversion Charts - Understanding International Units for Growth Hormone Peptides - Learn how concentration affects your syringe measurement
We'll walk you through each unit, show you exactly how to convert between them, and give you reference charts you can bookmark for daily use.
The Three Units You'll See in Peptide Dosing
Milligrams (mg) measure weight. One milligram is one-thousandth of a gram. Peptide vials are labeled in milligrams) for example, "BPC-157 5 mg" means the vial contains 5 milligrams of peptide powder.
Micrograms (mcg) also measure weight, at a smaller scale. One microgram is one-thousandth of a milligram. Most peptide doses are prescribed in micrograms because the effective amounts are very small. A typical BPC-157 dose of 250 mcg is only 0.25 mg.
International Units (IU) measure biological activity, not weight. IU are used for peptides like growth hormone (HGH) and some growth hormone secretagogues. The IU-to-mcg conversion varies by peptide because the measurement is based on how the peptide performs in standardized biological tests, not on how much it weighs.
The conversion between mg and mcg is always the same: - 1 mg = 1,000 mcg - 1 mcg = 0.001 mg
The conversion between IU and mcg is peptide-specific. Always use the conversion factor provided by your pharmacy or provider.
"What makes tirzepatide particularly interesting is the dual GIP/GLP-1 mechanism. We're seeing that GIP receptor activation appears to amplify the metabolic effects in ways we didn't fully anticipate from the preclinical data.", Dr. Ania Jastreboff, MD, PhD, Yale School of Medicine, lead author of SURMOUNT-1[1]
Quick Reference Conversion Charts
mg to mcg Conversion
| Milligrams (mg) | Micrograms (mcg) |
|---|---|
| 0.1 mg | 100 mcg |
| 0.25 mg | 250 mcg |
| 0.5 mg | 500 mcg |
| 1 mg | 1,000 mcg |
| 2 mg | 2,000 mcg |
| 2.5 mg | 2,500 mcg |
| 5 mg | 5,000 mcg |
| 10 mg | 10,000 mcg |
Common Peptide Doses in Both Units
| Peptide | Common Dose Range | In mg |
|---|---|---|
| BPC-157 | 200-500 mcg | 0.2-0.5 mg |
| TB-500 | 500-2,500 mcg | 0.5-2.5 mg |
| CJC-1295 | 100-300 mcg | 0.1-0.3 mg |
| Ipamorelin | 100-300 mcg | 0.1-0.3 mg |
| GHK-Cu | 200-600 mcg | 0.2-0.6 mg |
These ranges are for educational reference. Your provider determines your specific dose based on your clinical needs.
View data table
| Category | Clinical Interest Score | Detail |
|---|---|---|
| BPC-157 | 88 | Tissue repair and gut healing |
| TB-500 | 82 | Injury recovery |
| Sermorelin | 78 | Growth hormone support |
| Ipamorelin | 75 | Anti-aging and recovery |
| GHK-Cu | 70 | Skin and tissue repair |
Use the to convert your prescribed dose into exact syringe units (no manual math required.
Skip the math entirely. Use our free to get your dose in syringe units instantly.
How International Units for Growth Hormone Peptides
IU measurements come up most often with growth hormone (HGH) and growth hormone secretagogues.
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Try the BMI Calculator →For pharmaceutical HGH, the standard conversion is approximately: - 1 IU HGH = approximately 333 mcg (0.333 mg) - 3 IU HGH = approximately 1 mg
But this conversion can vary by manufacturer and specific product. Your pharmacy label should state both the IU content and the mg content. If it doesn't, ask your provider or pharmacist for the specific conversion factor for your product.
For growth hormone secretagogues like CJC-1295 and Ipamorelin, doses are typically prescribed in mcg, not IU. The IU designation is reserved for growth hormone itself, since the biological activity measurement was standardized for HGH.
If your prescription uses IU and your vial is labeled in mg (or vice versa), contact your provider before attempting to convert on your own. Getting this conversion wrong could mean a significant dosing error.
The lets you log doses in whatever units your provider prescribes, making it easy to keep accurate records regardless of the measurement system.
How Concentration Affects Your Syringe Measurement
Converting your dose from mcg to syringe units requires one more piece of information: your solution concentration. This depends on how much bacteriostatic water you added during reconstitution calculator.
Here's the complete chain of conversion:
- Know your vial content (example: 5 mg = 5,000 mcg)
- Know your water volume (example: 2 mL = 200 units on an insulin syringe)
- Calculate concentration (5,000 mcg / 200 units = 25 mcg per unit)
- Calculate your dose (250 mcg / 25 mcg per unit = 10 units)
This is where most confusion happens. The same dose in mcg translates to different syringe units depending on the concentration. If you reconstitute with 1 mL instead of 2 mL, your 250 mcg dose would be 5 units instead of 10.
That's why writing your concentration on the vial label is so important. If you pick up the vial tomorrow, you need to know the concentration to draw the right dose.
For a detailed guide on concentration calculations, see our . Or just use the and let it handle the math.
Frequently Asked Questions
Why don't peptide prescriptions use the same units as the vial label?
Vials are labeled in milligrams because that's the total content) useful for pharmacy tracking and ordering. Doses are in micrograms because the therapeutic amounts are tiny fractions of the total vial. A 5 mg vial might provide 20 doses at 250 mcg each. If prescriptions used milligrams, you'd be trying to measure 0.25 mg, which is harder to work with mentally.
Is 1,000 mcg the same as 1 mg?
Yes. One thousand micrograms equals one milligram. This is a fixed conversion that applies to all substances, not just peptides. When converting, move the decimal point three places: 1,000 mcg = 1.000 mg.
How do I know if my peptide should be dosed in IU or mcg?
Your provider and pharmacy will specify the correct units for your peptide. Generally, HGH uses IU. Most other peptides (BPC-157, TB-500, CJC-1295, Ipamorelin, GHK-Cu) use mcg. If your prescription and vial label use different units, ask for clarification before dosing.
Can I convert between peptide doses and syringe units without a calculator?
Yes, using the formula: syringe units = (dose in mcg / total mcg in vial) x total syringe units of water added. But the does this instantly and eliminates arithmetic mistakes. Even experienced users benefit from a double-check.
What happens if I accidentally dose in mg when my prescription is in mcg?
This would be a 1,000x overdose, which is dangerous. Always double-check your units before drawing your dose. If your prescription says 250 mcg and your vial contains 5 mg, your dose is a small fraction of the vial (not half of it. When in doubt, contact your provider before injecting.
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Medical References
- Jastreboff AM, Aronne LJ, Ahmad NN, et al. Tirzepatide Once Weekly for the Treatment of Obesity. N Engl J Med. 2022;387(3):205-216. [PubMed | ClinicalTrials.gov | DOI]
Sources &. References
- Sikiric P, Hahm KB, Blagaic AB, et al. Stable Gastric Pentadecapeptide BPC 157, Robert's Cytoprotection, Adaptive Cytoprotection, and Therapeutic Effects. Curr Pharm Des. 2018;24(18):1990-2001. Doi:10.2174/1381612824666180515125918
- Chang CH, Tsai WC, Lin MS, et al. The promoting effect of pentadecapeptide BPC 157 on tendon healing involves tendon outgrowth, cell survival, and cell migration. J Appl Physiol. 2011;110(3):774-780. Doi:10.1152/japplphysiol.00945.2010
- Seiwerth S, Brcic L, Vuletic LB, et al. BPC 157 and blood vessels. Curr Pharm Des. 2014;20(7):1121-1125. Doi:10.2174/13816128113199990421
- Bock-Marquette I, Saxena A, White MD, et al. Thymosin beta4 activates integrin-linked kinase and promotes cardiac cell migration, survival and cardiac repair. Nature. 2004;432(7016):466-472. Doi:10.1038/nature03000
- Malinda KM, Sidhu GS, Mani H, et al. Thymosin beta4 accelerates wound healing. J Invest Dermatol. 1999;113(3):364-368. Doi:10.1046/j.1523-1747.1999.00708.x
- Ionescu M, Frohman LA. Pulsatile secretion of growth hormone (GH) persists during continuous stimulation by CJC-1295, a long-acting GH-releasing hormone analog. J Clin Endocrinol Metab. 2006;91(12):4792-4797. Doi:10.1210/jc.2006-1702
Nothing in this article should be construed as medical advice. The information provided is educational only. Always consult with your healthcare provider before beginning, modifying, or discontinuing any medication or treatment. FormBlends connects patients with licensed providers for individualized care.
Last updated: 2026-03-24