Moles from Mass Calculator
Amount in moles = mass ÷ molar mass
Calculate amount of substance using entered mass and molar mass.
Formula
Amount in moles = mass ÷ molar mass
Worked example
Sample mass: 18.015 g
Molar mass: 18.015 g/mol
With these inputs, the result is 1 mol.
How to use this calculator
- Identify the quantity you want to calculate.
- Enter your measurements in the units shown on each field.
- Read the result, which updates as you change the inputs.
- Check the assumptions below before applying the result.
Assumptions and limits
The substance’s molar mass must be supplied; composition and purity are not inferred.
Precision and checking
Results are rounded for display. Use the most accurate measurements available, and avoid rounding your inputs unnecessarily. Extra decimal places in a result do not make an estimate more reliable.
To check a result, substitute the same input values into the formula shown above. Change one value at a time to understand how the quantity responds.
Frequently asked questions
What assumptions does this calculation use?
The substance’s molar mass must be supplied; composition and purity are not inferred.
Are my inputs sent to a server?
No. The calculation runs locally in your browser. The result updates as you edit the inputs.
Sources & references
- NIST Guide to the SI — National Institute of Standards and Technology
