Reconstitution 101
The universal math and technique behind every calculator on this site.
The 3-line formula
concentration (mg/mL) = vial mg ÷ water mL dose volume (mL) = dose mg ÷ concentration syringe units (U-100) = dose volume × 100
Example: 5 mg vial + 2 mL water = 2.5 mg/mL. A 250 mcg (0.25 mg) dose = 0.1 mL = 10 units.
Step by step
- Wash hands. Set out vial, BAC water, alcohol swabs, new sterile syringes, sharps container.
- Swab both rubber stoppers and let dry.
- Draw the water. Inject slowly down the glass wall of the peptide vial.
- Swirl gently. Don't shake. Wait until clear.
- Label with date and concentration. Refrigerate.
- Each dose: new syringe, draw to your calculated units, remove bubbles, inject, dispose in sharps.
Choosing syringe, pen or vial
Syringe + vial
Cheapest and most flexible. Use 0.3 or 0.5 mL syringes for small doses — easier to read.
Pen cartridge
Dial-a-dose and discreet. Requires a compatible cartridge; follow pen maker instructions.
Pre-mixed
Skips mixing. Check concentration (mg/mL) on the label, then use the pre-mixed tab.
Glossary
- Lyophilized
- Freeze-dried powder. Stable for months in the freezer.
- Reconstitute
- Mix the powder with a liquid (diluent) to make an injectable solution.
- BAC water
- Bacteriostatic water with 0.9% benzyl alcohol. Preserves multi-use vials.
- Unit
- On a U-100 insulin syringe, 1 unit = 0.01 mL. 100 units = 1 mL.
- mcg vs mg
- 1 mg = 1,000 mcg. Mixing these up is the most common (and dangerous) calculation mistake.
Red flags — discard the vial if
- Solution is cloudy, stringy or colored (unless the peptide is naturally tinted, like GHK-Cu).
- Past its use-by window or stored warm.
- The stopper has been punctured many times or looks contaminated.