Frequently asked questions
What is a BAC water calculator?
A BAC water calculator (bacteriostatic water calculator) figures out how much bacteriostatic water you need to mix with a lyophilized peptide vial to hit a target dose-per-unit. Enter peptide amount in mg, BAC water volume in mL, and desired dose in mcg or mg — the calculator returns the exact number of units to draw on a U-100 insulin syringe.
What is BAC water?
BAC water is bacteriostatic water — sterile water containing 0.9% benzyl alcohol that prevents bacterial growth. It is the standard diluent for reconstituting lyophilized (freeze-dried) research peptides because the benzyl alcohol keeps the reconstituted solution stable in the refrigerator for several weeks.
How much BAC water should I add to a peptide vial?
There is no single correct volume. Most users add between 1 mL and 3 mL of BAC water per vial, depending on the peptide amount and how concentrated they want each unit. The Peptides Calculator app lets you pick any volume between 0.5 mL and 5 mL and instantly shows the resulting unit-per-dose draw.
How do I read the result on an insulin syringe?
The result is in "units" on a U-100 insulin syringe — the same syringe used for insulin injections, with 100 markings between 0 and 1 mL. A 25-unit result means draw to the 25 line; that delivers 0.25 mL of your reconstituted peptide solution.
Is the BAC water calculator free?
Yes. Peptides Calculator is free on the web, iOS, and Android. The BAC water math, syringe overlay, peptide library, half-life calculator, and stack builder are all available without signup.
Want more than a one-shot calculator?
The free Peptides Calculator app saves every vial you reconstitute, tracks remaining doses, sends reminders, and visualizes half-life decay — all without a signup. Free on iOS and Android.