Peptide molarity calculator
Convert a weighed mass and volume to mg/mL, mM and µM, or work back from a target concentration to the mass to weigh. Pick a catalog compound for its PubChem molecular weight, or enter any value.
How the calculation works
Molarity is moles per litre: the peptide mass in grams divided by its molecular weight, divided by the volume in litres. Net peptide content scales the weighed mass down to the peptide itself before the conversion, and scales the mass to weigh up by the same factor. Molecular weights in the list are PubChem computed values; the molecular weight reference shows the formula and CAS number behind each one, and the molecular weight calculator handles any other sequence.
Questions
How do you calculate peptide molarity?
Molarity (mol/L) = mass (g) ÷ (molecular weight (g/mol) × volume (L)). For 1 mg of BPC-157 (1,419.5 g/mol) in 1 mL: 0.001 ÷ (1,419.5 × 0.001) = 0.704 mM, or 704 µM.
What is net peptide content and why does it matter?
A lyophilized peptide powder also holds counter-ions (acetate or TFA) and bound water, so the peptide itself is usually less than 100% of the weighed mass. If the analysis reports net peptide content, enter it and the calculator corrects both directions.
Which molecular weight should I use for a salt form?
Use the peptide's own molecular weight and correct the weighed mass with net peptide content. Using the salt's formula weight gives the same answer only when the salt stoichiometry is known exactly.
Average or monoisotopic mass for molarity?
Average mass. It reflects natural isotope abundance, which is what a balance weighs. Monoisotopic mass is for reading mass-spec peaks.
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Reference tools for laboratory research. Not for human or animal use.