How the peptide reconstitution math works
Every U-100 insulin syringe holds 100 units per 1 mL, no matter its size. A 30U syringe is 0.3 mL, a 50U is 0.5 mL, a 100U is 1 mL. So the only two things that decide your draw are how much peptide is in the vial and how much water you mixed into it.
- Concentration = vial mg ÷ water mL. A 5 mg vial with 2 mL of water is 2.5 mg/mL.
- Amount per unit = concentration × 1,000 ÷ 100. At 2.5 mg/mL, each unit carries 25 mcg.
- Units to draw = dose in mcg ÷ mcg per unit. A 250 mcg dose is 10 units.
Which syringe should I use?
Use the smallest syringe your draw fits in. Small draws on a big syringe are hard to read; a 3U draw on a 100U syringe is a guess, the same draw on a 30U syringe is clear. If your draw is under 5U, add more water next time so the draw lands between 10U and the syringe's capacity.
Why the calculator warns me
If the draw is larger than the syringe, you would need two draws or a bigger syringe. If the draw is tiny, measurement error becomes a real percentage of the dose. Both warnings tell you exactly how much water would fix it.
Common questions
Does the vial size change the math? Only through concentration. The peptide mass and the water volume are what matter; the glass is irrelevant.
What is a "unit"? A tick on a U-100 insulin syringe: 1/100 of a millilitre, 0.01 mL.
Can I use a 3 mL syringe? It is not marked in U-100 units. Convert the result to mL (shown above the syringe) and draw that volume.
This calculator performs arithmetic on the numbers you enter. It is for educational and research reference only and is not medical advice, a dosing recommendation, or a substitute for guidance from a qualified professional. Verify every value against the product label. Products sold by ThePeptideStore are for research use only. These statements have not been evaluated by the FDA.
Is this calculator free?
Yes. No account, no email, nothing to install. It runs in your browser and saves your last settings on your device only.