How the calculation works
Concentration is simply the mass of peptide divided by the volume of bacteriostatic water you added:
- mg/ml = peptide (mg) ÷ water (ml)
- mcg/ml = mg/ml × 1000
To measure a specific amount, divide your target aliquot (mcg) by the concentration (mcg/ml) to get the volume in ml. On a standard U-100 insulin syringe, 100 units = 1 ml, so units = ml × 100. The unit markings on a U-100 syringe are the easiest way to measure small volumes accurately in the lab.
Reconstitute a 10 mg vial with 2 ml of bacteriostatic water → 5 mg/ml (5000 mcg/ml). To measure a 250 mcg aliquot: 250 ÷ 5000 = 0.05 ml = 5 units on a U-100 syringe.
Reconstitution best practice
- Add the bacteriostatic water slowly down the inner glass wall, not directly onto the powder.
- Swirl gently — never shake. Agitation causes foaming and can damage the peptide.
- Store the reconstituted vial refrigerated at 2–8 °C and use within a few weeks; never freeze a reconstituted solution.
- Label the vial with its concentration and the date of preparation.
For the full technique and storage detail, see our guides on reconstituting Retatrutide and storage. Need bacteriostatic water? It's in the shop, free with orders over £150.
This calculator is provided to help qualified researchers prepare and measure laboratory stock solutions. It is not dosing guidance and the compounds referenced are not for human consumption. Always verify calculations independently for your protocol.
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