Free tool
Reconstitution Calculator
Enter your vial size, the volume of BAC water you added, and your target dose. The calculator will tell you exactly how many units to draw on your insulin syringe.
Enter values above to calculate.
No data is saved. All calculations run locally in your browser. Verify all results independently.
How reconstitution math works
Peptides are typically sold as lyophilized (freeze-dried) powder in a vial measured in milligrams (mg) or micrograms (mcg). Before injection, you dissolve the powder in bacteriostatic water (BAC water) to create a solution.
Step 1 — Find the concentration. Divide the total vial content (mg) by the volume of BAC water added (mL). For example, a 5 mg vial reconstituted with 2 mL of BAC water yields a concentration of 2.5 mg/mL.
Step 2 — Find the volume for your dose. Divide your target dose (converted to mg) by the concentration. For a 250 mcg (0.25 mg) dose at 2.5 mg/mL, you need 0.1 mL.
Step 3 — Convert to syringe units. A U-100 syringe has 100 units per mL, so 0.1 mL = 10 units. A U-50 syringe has 50 units per mL, so 0.1 mL = 5 units.
Always double-check your calculations. This tool is a convenience aid, not a substitute for careful manual verification.
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