Peptide Reconstitution Calculator
You already know your dose. We tell you exactly where to draw to on the syringe.
Enter your vial, your bacteriostatic water, and your target dose. The calculator converts it into syringe units in real time. No accounts, no tracking of your inputs.
Reconstitution calculator
Show the math
Enter values above to see the step-by-step math.
Calculators by peptide
Each calculator is pre-filled with a common vial size for that peptide and includes factual, non-promotional information about vial sizes, reported half-life, and storage.
GLP-1 Agonists
Healing & Recovery
Growth Hormone Secretagogues
Cosmetic
Longevity & Metabolic
How reconstitution math works
Reconstitution is the process of mixing a lyophilized (freeze-dried) peptide with a sterile liquid — typically bacteriostatic water — so that it can be measured and drawn into a syringe. The math itself is a two-step unit conversion.
Step 1: concentration. Divide the peptide mass (in mg) by the volume of bacteriostatic water added (in mL). A 5 mg vial mixed with 1 mL of water produces a 5 mg/mL solution, or 5,000 mcg/mL.
Step 2: draw volume. Divide your target dose (converted to mcg) by the concentration in mcg/mL. The result is the volume in mL you need to draw. Multiply that volume by the units-per-mL of your syringe (100 for U-100, 40 for U-40) to get the number of marked units to draw to.
That's it. No magic — just dimensional analysis. The calculator above automates these steps and flags two safety conditions: when the required draw would exceed the syringe's capacity, and when the required volume is too small to measure accurately on the chosen syringe. For both cases, you can adjust your dilution or your syringe choice.
Common reconstitution mistakes
These are the most frequently reported sources of math errors in published user discussions and research protocols.
- Confusing mg and mcg. 1 mg = 1,000 mcg. Most peptide dose targets are expressed in mcg; most vial labels are in mg.
- Confusing U-100 and U-40 syringes. Same physical volume, different scales. A "10 unit" mark on a U-40 syringe is 2.5× the volume of a "10 unit" mark on a U-100.
- Assuming "draw to 10 units" means 0.1 mL on any syringe. That's only true on a U-100. On a U-40, 10 units = 0.25 mL.
- Under-diluting a potent peptide. Very small draw volumes are hard to measure accurately. Adding more bacteriostatic water increases the draw volume per dose.
- Over-diluting a less potent compound. If your required draw exceeds the syringe barrel, either switch to a larger syringe or reconstitute with less water next time.
- Forgetting that mg-per-mL is not mcg-per-unit. Concentration and draw are two separate conversions. Always compute both — the calculator above shows them side by side.
Free Peptide Reconstitution Cheat Sheet (PDF)
A one-page reference with common vial-to-dose conversions. Educational only — not medical advice.
Guides
Long-form educational articles on reconstitution, insulin syringe markings, bacteriostatic water, storage, and more.