Guide
How to Reconstitute Peptides: The Math
Reconstituting a peptide means dissolving the powder in a measured volume of liquid, usually bacteriostatic water. The math is one division: amount in the vial ÷ liquid added gives the concentration, and every volume follows from it.
What reconstitution means
Lyophilized (freeze-dried) peptides come as powder. Adding a known volume of liquid turns them into a solution with a known concentration, so an amount can be measured as a volume.
The liquid doesn’t change the amount in the vial: a 10 mg vial holds 10 mg whether you add 1 mL or 5 mL.
The math
concentration = amount in the vial ÷ liquid addedvolume = amount you choose ÷ concentrationU-100 units = volume (mL) × 100Worked examples
| Vial | Liquid | Concentration | Amount | Volume | U-100 units |
|---|---|---|---|---|---|
| 5 mg | 2 mL | 2.5 mg/mL | 250 mcg | 0.10 mL | 10 |
| 10 mg | 2 mL | 5 mg/mL | 500 mcg | 0.10 mL | 10 |
| 10 mg | 3 mL | 3.333 mg/mL | 500 mcg | 0.15 mL | 15 |
| 2 mg | 1 mL | 2 mg/mL | 100 mcg | 0.05 mL | 5 |
Put any row into the reconstitution calculator to see the same numbers and the nearest syringe marking.
Choosing the liquid volume
The volume is a measuring choice. More liquid means each amount takes more volume, which is easier to read on a syringe but needs more liquid per portion. Less liquid concentrates it. There is a full explanation in how much bacteriostatic water to add.
Handling and storage
This guide covers the arithmetic only. For handling, sterile technique and storage, follow the product’s own documentation and your research protocol.
Frequently asked questions
What does it mean to reconstitute a peptide?
To dissolve its powder in a measured volume of liquid, giving a solution with a known concentration.
How do you calculate peptide reconstitution?
Divide the vial amount by the liquid volume for the concentration, then divide your amount by the concentration for the volume.
How long does a peptide last after reconstitution?
That depends on the compound and its supplier’s stability data, so no single figure applies. Check the product’s documentation.
Related calculators and guides
- CalculatorReconstitution calculatorWork out concentration after adding bacteriostatic water, then the mL and U-100 units for any amount.
- GuideHow Much Bacteriostatic Water to AddThe volume of bacteriostatic water you add sets the concentration, not the amount.
- GuideBacteriostatic Water ExplainedWhat bacteriostatic water is, how it differs from sterile water, and where to find storage and use-by information on its label.
- GuideInsulin Syringe Units Explained1 mL is 100 units on a U-100 syringe.
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