Peptide Calculator

Bacteriostatic Water

Bacteriostatic water (BAC water) is sterile water containing 0.9% benzyl alcohol as a preservative. It is the standard diluent for peptide reconstitution in research contexts because benzyl alcohol inhibits bacterial growth, allowing a reconstituted solution to be used over multiple days without becoming a contamination risk. BAC water is distinct from plain sterile water (single-use) and from bacteriostatic saline (which contains 0.9% sodium chloride in addition to benzyl alcohol). Most research peptide protocols describe using BAC water with a multi-dose vial.

Reading Insulin Syringe Units (U-100 vs U-40)

Insulin syringes are calibrated in "units" rather than millilitres. The most common type is the U-100 syringe, which is calibrated at 100 units per mL — meaning 1 unit on the syringe equals 0.01 mL. A less common type, U-40, is calibrated at 40 units per mL (1 unit = 0.025 mL), and is still used in some countries.

To convert a volume in mL to insulin syringe units: multiply the volume by 100 for a U-100 syringe, or by 40 for a U-40 syringe. For example, 0.1 mL = 10 units on a U-100 syringe. Using the wrong syringe type without adjusting your calculation will result in the wrong dose drawn.

Full Reconstitution Guide

For step-by-step instructions covering reconstitution technique, syringe preparation, injection site selection, and storage after reconstitution, see the full guide.