Calculator
Peptide reconstitution and syringe calculator
Choose the compound and vial size, the water added and your syringe, then enter the amount you want to measure. The calculator shows what to draw to on that syringe's own scale (units or mL), and which of its marks that falls between.
Measuring errors are common and can be serious. The FDA has received reports of people injecting five to 20 times the intended amount of compounded semaglutide, after mistakes converting milligrams to syringe units, confusion between units of measurement, and syringes much larger than the volume needed. Some needed hospital care (FDA, July 26, 2024).
This calculator doesn't tell you what amount to use. For most research peptides no human dose has been established; each peptide guide lists the doses used in published studies, with sources.
How it's worked out
- Concentration = peptide in the vial ÷ water added. 10 mg in 2 mL is 5 mg per mL, which is 5,000 mcg per mL.
- Volume for an amount = amount ÷ concentration. 250 mcg at 5,000 mcg per mL is 0.05 mL.
- Insulin-syringe units depend on the syringe: on a U-100 syringe 1 unit is 0.01 mL, so 0.05 mL is 5 units; on a U-40 syringe 1 unit is 0.025 mL, so the same 0.05 mL is 2 units. Reading one syringe's scale as the other's is a 2.5-fold error.
- Reading the marks: a syringe can only be read to its marks (every unit on 0.3 mL and 0.5 mL U-100 syringes, every 2 units on 1 mL ones, every unit on U-40 ones, and every 0.01 mL or 0.1 mL on syringes marked in mL). When a reading falls between two marks, the calculator shows both and how much each holds.
- 1 mg = 1,000 mcg. Mixing up mg and mcg is a thousandfold error, so the calculator always shows both.
The figures assume the vial holds what its label says. Independent tests of unapproved products often find less, or more, than the label (how peptide testing works).