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Mass / Molarity calculator

How much powder do you weigh in for a solution? Enter the molecular mass, the final volume and the concentration. Added too much? The calculator tells you how much more solvent brings it back.

g/mol

Not sure? Work it out from the formula. Leave empty for %(m/v).

I accidentally added too much!

How much did you add? The calculator works out how much more solvent you need to reach the same concentration.

Decimals and rounding

Far left picks a sensible number of decimal places for each value.

How it works

For molar concentrations the mass is concentration × volume × molecular mass. For %(m/v) the molecular mass is not needed: 1 % is 1 g in 100 ml.

If you weighed in more than needed, the extra solvent is volume × added ÷ required − volume. You end up with more solution at the same concentration.