Peptide Reconstitution Calculator
Work out the concentration of a reconstituted lyophilized peptide and the volume of solution that contains a given amount. Concentration in mg/mL is numerically the same as µg/µL, which makes small aliquots easy to plan.
How the calculation works
Concentration is the mass of peptide divided by the volume of diluent: C (mg/mL) = mass (mg) ÷ volume (mL). Because 1 mg/mL equals 1 µg/µL, the volume that contains a target amount is simply the target in micrograms divided by the concentration: V (µL) = target (µg) ÷ C (mg/mL). The number of whole aliquots is the total mass in micrograms divided by the target, rounded down.
Worked example
A vial containing 10 mg of lyophilized peptide is reconstituted with 2 mL of bacteriostatic water. The concentration is 10 ÷ 2 = 5 mg/mL, which is 5 µg/µL. An aliquot of 250 µg therefore needs 250 ÷ 5 = 50 µL of solution, and the vial yields 10,000 ÷ 250 = 40 aliquots.
Accuracy notes for the lab
The label states the gross fill. Net peptide content, the actual peptide after counter-ions and residual water, is usually lower. Use the net peptide value from the Certificate of Analysis when exact molar amounts matter.
Pipette the diluent with a calibrated pipette rather than estimating from vial graduations, and let the cake dissolve fully before drawing an aliquot.
Choose a volume that gives an easy-to-measure concentration. Very small aliquot volumes amplify pipetting error.
Step-by-step reconstitution guide →
Bacteriostatic water for reconstitution →