Peptide reconstitution calculator
Add bacteriostatic water to a lyophilized vial, then draw the right volume on a U-100 insulin syringe. Enter your numbers below — it solves for the units to draw, the water to add, or the dose a draw delivers, with a visual syringe and an mg/mcg safety check.
New to reconstitution? Read the step-by-step guideNew to this? How to use the calculator
- 1Enter what's on your vial. Type the peptide amount (mg) printed on the vial and the mL of bacteriostatic water you mixed in. Not sure how much water to add? Switch to the Solve: water tab and it tells you.
- 2Enter your dose — mind the unit. Type your target dose and pick mg or mcg with the toggle. This matters: 1 mg = 1000 mcg. GLP-1s (semaglutide, tirzepatide) are usually mg; most peptides (BPC-157, ipamorelin) are mcg.
- 3Read “Draw to … units”. The big number is how far to pull the plunger on a U-100 insulin syringe. Match it to the fill line on the syringe picture. The concentration and doses per vial are shown so a wrong answer looks wrong.
Three ways to use it: Solve: units (you have a dose, find the draw), Solve: water (you want a clean mark like 10 units, find the water), and Solve: dose (you drew some units, find the dose).
Full step-by-step guideI have a vial, water and a dose — how many units do I draw?
Enter your vial, water and dose to see the draw.
This tool computes volumes only — it does not recommend doses. Any pre-filled values are commonly-referenced examples to confirm with your provider. Always verify the concentration and draw against your own vial and syringe.
How reconstitution math works
With P mg of peptide in the vial and W mL of BAC water, the concentration is C = P / W mg/mL. For a dose D mg the volume is V = D / C mL, and on a U-100 syringe (100 units = 1 mL) you draw U = 100 × D × W / P units.
Example: a 5 mg vial + 2 mL water gives 2.5 mg/mL. A 0.25 mg dose is 100 × 0.25 × 2 / 5 = 10 units — 20 doses per vial. The single most dangerous slip is mg vs mcg (1 mg = 1000 mcg), so the calculator makes you pick the unit and shows the concentration so a wrong answer looks wrong.
Reconstitution calculators by compound
Each page pre-fills common vial sizes, water volumes and example doses for that compound.