Calculating Peptide Concentration
Peptide concentration is the labelled vial amount divided by the volume of liquid added: concentration (mg/mL) = mg ÷ mL.
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The formula
Concentration (mg/mL) = vial amount (mg) ÷ diluent volume (mL)
Concentration (mcg/mL) = concentration (mg/mL) × 1000
Worked examples
- 5 mg vial + 1 mL → 5 mg/mL (5000 mcg/mL)
- 5 mg vial + 2 mL → 2.5 mg/mL (2500 mcg/mL)
- 10 mg vial + 1 mL → 10 mg/mL
- 10 mg vial + 2 mL → 5 mg/mL
- 30 mg vial + 3 mL → 10 mg/mL
Choosing a workable concentration
Concentration is the one variable fully under your control at reconstitution time. A higher concentration means smaller, harder-to-read draws; a lower concentration means larger, easier-to-read draws but a shorter supply per vial if vial capacity limits how much liquid you can add.
Round concentrations — 5, 10 or 20 mg/mL — make mental checks straightforward, because the syringe reading becomes a simple multiple of the target amount.
Vial capacity is a hard limit
You cannot add more liquid than the vial physically holds. A 3 mL vial constrains a 30 mg peptide to a minimum of roughly 10 mg/mL. PepCalcs validates the requested volume against the vial size you enter.