How peptide reconstitution works

Research peptides ship as a freeze-dried (lyophilised) powder. Before they can be measured, the powder is reconstituted — dissolved in bacteriostatic water. Once mixed, the vial holds a known concentration: the amount of peptide divided by the volume of water added.

The maths is simple. A 10mg vial reconstituted with 2mL of water holds 5mg per mL, or 5,000mcg per mL. To measure a 250mcg aliquot, you need 250 ÷ 5,000 = 0.05mL — which is 5 units on a U-100 syringe scale. This calculator does that conversion instantly for any vial size, water volume and target amount.

How to use the calculator

1. Peptide in vial — the milligrams listed on your product (e.g. 10mg).
2. Bacteriostatic water added — how much water you mix in. 1–3mL is typical; more water spreads the amount across more syringe units, making small measurements easier to read accurately.
3. Target amount — the amount of peptide you want per aliquot, in mcg or mg.
4. Read the result in units (the mark to draw to on a syringe scale) and in mL.

A worked example

Reconstitute a 5mg vial with 2mL of water and you have 2,500mcg/mL. For a 200mcg aliquot, draw 0.08mL — 8 units on a U-100 scale — and the vial yields about 12 aliquots.

Tips for accurate measuring

• Add water slowly down the side of the vial; never inject it forcefully onto the powder.
• Swirl gently to dissolve — don't shake.
• If your aliquot lands on an awkward number of units, adjust the water volume and recalculate until it sits on a clean, easy-to-read mark.
• Store reconstituted vials refrigerated at 2–8°C.