This peptide molarity calculator converts peptide mass and molecular weight into molar concentration, or tells you how much solvent to add for a target.
How to use the Peptide Molarity Calculator
- Choose the solve for.
- Enter the peptide mass and choose mg or mcg or g.
- Enter the molecular weight.
- Enter the solvent volume, or tap a preset when it appears.
- Enter the target concentration and choose mM or µM or M, or tap a preset when it appears.
- Read the result card. It updates as you type, and you can copy or share it.
About this calculator
Use the net peptide weight when your certificate of analysis lists peptide content. Lyophilized peptides often contain 10–30% counter-ions and water by mass, which lowers the true molar amount.
Frequently asked questions
Should I use the salt form molecular weight?
If you weigh the salt form, use its molecular weight or correct the mass for net peptide content.
Sources
- Amount concentration (IUPAC Gold Book). International Union of Pure and Applied Chemistry.
- ProtParam tool. Expasy, SIB Swiss Institute of Bioinformatics.
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Medical disclaimer. This calculator is for educational purposes only and is not medical advice. Results are mathematical estimates based on the values you enter. Many peptides listed here are not approved by the FDA for human use. Confirm every dose with a licensed healthcare provider or your approved study protocol, and follow the product label.
