Peptide Reconstitution Calculator
Enter your vial strength and solvent volume to get concentration, draw volume, and syringe-unit readouts for U-100, U-50, and U-40 insulin syringes. Free, instant, nothing stored.
concentration (mg/mL) = vial strength (mg) ÷ solvent (mL)
draw volume (mL) = desired amount (mg) ÷ concentration
syringe units = draw volume × syringe scale (U-100 = 100 units/mL)
How reconstitution math works
Reconstitution is dilution arithmetic. A lyophilized vial labeled with its total strength (say 10 mg) is rehydrated with a measured solvent volume (say 2 mL). Everything you need follows from one division:
concentration = strength ÷ solvent. With the example numbers, 10 mg ÷ 2 mL = 5 mg/mL. Every draw volume is then that concentration applied backwards: want 250 mcg (= 0.25 mg)? Draw 0.25 ÷ 5 = 0.05 mL, which reads as 5 units on a U-100 insulin syringe, 2.5 units on U-50, 2 units on U-40.
The two mistakes people make are mixing units (mcg vs mg — a factor of exactly 1000) and reading a U-50 syringe as if it were U-100 (a factor of exactly 2). This calculator shows all three scales at once so a scale mix-up is visible immediately, and converts mcg internally.
Worked examples
| Vial | Solvent | Want | Draw | U-100 |
|---|---|---|---|---|
| 10 mg | 2 mL | 250 mcg | 0.05 mL | 5 units |
| 5 mg | 1 mL | 500 mcg | 0.10 mL | 10 units |
| 30 mg | 3 mL | 3 mg | 0.30 mL | 30 units |
| 2 mg | 0.5 mL | 100 mcg | 0.025 mL | 2.5 units |
About DoseTrail
This calculator is the free web version of the one built into DoseTrail — a private, pay-once iPhone companion that adds dose scheduling, injection-site rotation, weigh-in trends, supply countdowns, and a PDF log you can hand your doctor. One purchase, no subscription, no account — the app has no network access at all, so your data physically cannot leave your phone.
This tool does arithmetic, nothing else. It computes what you enter and never recommends any amount of anything. Verify every result independently — ideally by hand with the formula above — and consult a licensed professional for anything health-related.