Peptide Reconstitution Calculator
This is a dilution calculator for reconstituted peptide vials. Lyophilised peptides arrive as a freeze-dried powder measured in milligrams, and are reconstituted by adding a measured volume of diluent, usually bacteriostatic water. The arithmetic that follows is simple but easy to get wrong under pressure, because it crosses three units and two scales: the vial is labelled in milligrams, the amount you want is usually described in micrograms, and the syringe is marked in insulin units rather than millilitres. A U-100 syringe has 100 units to the millilitre, so a tenth of a millilitre reads as 10 units, and that translation is where most errors happen. Enter the vial strength, the volume of diluent you added and the amount you want, and the calculator returns the concentration of the solution, the volume that amount occupies, the reading on the syringe and how many of that amount the vial holds. It handles U-100, U-50 and U-30 syringes, since the unit markings differ between them and a number read off the wrong barrel is a tenfold class of error. This is arithmetic only. It is not medical advice, it does not recommend any amount, and nothing here should be used to guide use in humans or animals.
Arithmetic only. This is not medical advice and recommends no amount. Peptides sold as research chemicals are not approved for human or veterinary use. Follow the directions of a qualified health professional.
How it works
Concentration is the peptide in the vial divided by the diluent volume, converted to micrograms per millilitre by multiplying milligrams by 1,000. The volume needed for a given amount is that amount divided by the concentration. Insulin syringes are marked in units rather than millilitres: a U-100 syringe has 100 units to the millilitre, so the volume in millilitres multiplied by 100 gives the reading. U-50 and U-30 syringes use the same 100 units per millilitre scale but hold 0.5 mL and 0.3 mL respectively, so the calculator also tells you whether the volume fits in the barrel. Amounts per vial is the total peptide divided by the amount wanted.
Worked example
Take the defaults: a 5 mg vial reconstituted with 2 mL of bacteriostatic water, wanting 250 mcg. The vial holds 5 x 1,000 = 5,000 micrograms, so the concentration is 5,000 divided by 2, which is 2,500 mcg per mL. For 250 mcg you need 250 divided by 2,500, which is 0.1 mL. On a U-100 syringe that is 0.1 x 100 = 10 units. The vial holds 5,000 divided by 250, which is 20 of that amount. Add twice the water, 4 mL, and the concentration halves to 1,250 mcg/mL, so the same 250 mcg becomes 0.2 mL and reads 20 units instead.
Related calculators
- Dilution (C1V1 = C2V2): the general dilution equation.
- Molarity: concentration in moles per litre.
- Unit Converter: length, weight, volume and more.
- Current Converter: another exact-factor unit conversion.