Peptide Reconstitution Calculator
Draw to
On a U-100 insulin syringe. 100 units = 1 mL.
How the calculator works
It runs three numbers through one chain of arithmetic:
- Concentration = vial strength divided by water volume. A 10 mg vial in 2 mL of bacteriostatic water is 5 mg/mL.
- Draw volume = your dose divided by the concentration. A 250 mcg dose at 5 mg/mL is 0.05 mL.
- Units = draw volume times 100, because a U-100 syringe has 100 units per mL. 0.05 mL is 5 units.
The tool also flags the friendly 10 mg/mL ratio, where 1 mg equals 10 units, and warns you if a dose would overflow a 100-unit syringe or land too small to measure accurately.
How to reconstitute a peptide, step by step
- Decide how much bacteriostatic water to add. More water makes small doses easier to measure.
- Add the water slowly down the inside wall of the vial, not directly onto the powder.
- Swirl gently or let it sit until the solution is clear. Do not shake.
- Enter your vial strength, water volume, and dose above to read the exact units to draw.
How much bacteriostatic water should you add?
There is no single correct volume. The goal is a concentration that makes your dose easy to read on the syringe. Round concentrations like 5 mg/mL or 10 mg/mL keep the mental math simple. Use the recommended-water button in the calculator to land on a clean number of units automatically.
Reading units on a U-100 insulin syringe
U-100 means 100 units per mL, so the whole 1 mL barrel is 100 units, the halfway mark is 50 units, and 10 units is one tenth of the barrel. The calculator highlights the exact tick to draw to, so you are never guessing between lines.
Frequently asked questions
- How do you calculate peptide reconstitution?
- Divide the peptide amount in the vial by the volume of bacteriostatic water you add to get the concentration (for example 10 mg in 2 mL is 5 mg/mL). Divide your target dose by that concentration to get the volume to draw, then multiply by 100 to read it as units on a U-100 insulin syringe.
- How much bacteriostatic water should I use?
- Any volume works mathematically. More water lowers the concentration and makes a small dose easier to measure on the syringe; less water means a smaller injection volume. The recommended-water option finds a volume that lands your dose on a clean, whole number of units.
- How do I convert mg or mcg to insulin syringe units?
- On a U-100 syringe, 100 units equals 1 mL. So units to draw equals your dose volume in mL times 100. The calculator does this for you and highlights the exact tick on the syringe.
- How many doses are in one vial?
- Divide the total amount in the vial by your per-injection dose and round down. The calculator shows doses per vial automatically and, with a price entered, the cost per dose.
- Is bacteriostatic water the same as sterile water?
- No. Bacteriostatic water contains a small amount of benzyl alcohol that inhibits bacterial growth, which is why it is commonly used for multi-use research vials. Sterile water has no preservative. See our guide on the difference.
Related calculators and guides
Keep this calculation in your pocket
Stackr saves every vial you reconstitute, tracks doses remaining, and reminds you to reorder before you run out. The reference app for people who take their protocol seriously.
Educational tool only, not medical advice. Peptides are research chemicals, not for human consumption. Full disclaimer.