Concentration and Measurement Calculations
for Peptide Reconstitution
Enter the numbers on your vial. We work out the concentration, how much to measure, and how many syringe units that is. We show every step, and label every number by where it came from.
What is bacteriostatic water?
Bacteriostatic water is sterile water with 0.9% benzyl alcohol in it. Sterile means it had no germs in it when it was made. The benzyl alcohol, a preservative, slows germs from growing after you open the vial, so you can use the same vial more than once. It is not safe for newborn babies. People use it to turn dried peptide powder into a liquid they can measure. The calculators here work out how much to add.
- What is bac water?
- Sterile water plus 0.9% benzyl alcohol preservative.
- How much water for a 5 mg vial?
- It depends on how strong you want the liquid. Use the calculator instead of guessing.
- How long can an opened vial be used?
- Follow the instructions that came with your product. General advice does not tell you how long yours lasts.
- Units to mL
- 100 units = 1 mL on a U-100 syringe.
- mg to mcg
- 1 mg = 1,000 mcg.
Build my plan
Answer a few short questions about the numbers on your vial and get an exact reconstitution plan with every step shown, syringe units, a PDF, and a printable label.
Calculators
Already know your numbers? Use a single calculator: how much water to add, how many syringe units, mg to mcg, and more.
Learning center
Plain-language guides on bacteriostatic water, how the math works, reading a syringe, and what you cannot know about your vial.
How the math works.
- Enter your numbersCompound, vial amount, how much you want to measure, and your syringe.
- See every stepConcentration, how much to measure, syringe units, and how many measurements per vial, with the formula shown.
- Download, print, saveA PDF and a printable vial label with a QR code back to the plan.
- Every number labeledWhat you typed, what the site worked out, and what it did not decide.
- Vial amount
- 5 mg
- BAC water
- 2 mL
- Concentration
- 2.5 mg/mL
- Amount to measure
- 0.25 mg (250 mcg)
- Syringe units
- 10 units
- Measurements per vial
- 20
This measures 10 units on a 1 mL insulin syringe.
Compounds and guides
Open the reconstitution calculator and reference for a compound, or compare bacteriostatic water with other diluents.
Here is the formula, your numbers, and how we round.
Every answer shows its work. Concentration is the vial amount divided by the water you add. We keep full precision inside and round only when we show a number. If an amount lands between the marks on your syringe, we tell you, because you cannot measure it. The AI helper explains the result in plain words. It never does the math itself.