Moles to Grams Calculator
Convert mol, mmol, micromoles or nanomoles to grams using a supplied molar mass. See equivalent mass in mg and kg and check the normalized amount.
Calculate the mass corresponding to a known amount of substance. Enter moles or a smaller amount unit and supply the molar mass of the material you intend to use. This is useful for checking a target reagent quantity before accounting for purity or practical preparation losses.
How to use this tool
- Enter the required amount and choose mol, mmol, µmol or nmol.
- Enter the material’s molar mass in g/mol.
- Read grams, milligrams and kilograms.
- Check the normalized amount in mol and confirm the chemical form matches your molar mass.
Formula
m = n × M; 1 mmol = 10^-3 mol; 1 µmol = 10^-6 mol; 1 nmol = 10^-9 mol
m is mass in grams, n is the normalized amount in mol, and M is molar mass in g/mol. Prefix conversion applies to the amount input. The molar-mass input always stays in g/mol.
Example
At 58.44 g/mol, an amount of 0.25 mol has mass 0.25 × 58.44 = 14.61 g. That is 14,610 mg or 0.01461 kg. Entering 250 mmol gives the same mass.
Frequently asked questions
Is mmol the same as mM?
No. Millimoles describe an amount. The symbol mM usually means millimoles per liter, a concentration. To use a concentration, first multiply it by the appropriate solution volume to obtain an amount.
Can the same number of moles have different masses?
Yes. Mass depends on molar mass. Different substances, hydration states or isotope compositions can have different masses for the same amount of specified entities.
Does the result tell me how much commercial reagent to weigh?
It gives the pure-substance mass represented by your inputs. A commercial preparation may contain solvent, water or impurities. Any required assay correction must use information specific to that material.
How are very small masses displayed?
Scientific notation avoids rounding a nonzero result to zero. For example, 1e-7 g means 0.0000001 g. The calculation does not choose a balance, assess handling feasibility or propagate measurement uncertainty.
Sources
Last updated: 2026-10-30