The formula
mass concentration (g/L) = molar concentration (mol/L) × molecular weight (g/mol)
Useful equivalences: 1 mg/mL = 1 g/L = 1 µg/µL; 1 ng/µL = 1 µg/mL; 1% w/v = 10 mg/mL.
Worked example
BSA at 5 mg/mL with a molecular weight of 66,430 g/mol: 5 g/L ÷ 66,430 g/mol = 75.27 µM.
Common questions
My protein's weight is given in kDa. What do I enter?
A dalton (Da) is the same number as g/mol, so 66.43 kDa is 66,430 g/mol.
Why do some rows say "needs MW"?
Converting between molar and mass units needs a molecular weight. Within one family (say µM to nM) it doesn't.
This calculator is checked against independent calculations before every release. How we check our calculators.