Mols (n = m/M)
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
About this calculator
The moles calculator (n = m/M) converts the mass of a substance into moles or vice versa. It uses the formula n = m/M, where 'n' is the number of moles, 'm' is the mass of the sample (in grams), and 'M' is the molar mass (g/mol). This tool is fundamental in chemistry for stoichiometric calculations, such as balancing equations or preparing solutions.
To use it, input two of the three values (mass, molar mass, or moles) you want to calculate. The calculator automatically applies the correct formula. For example, if a sample has a mass of 50g and a molar mass of 25g/mol, the result will be 2 moles. Ensure units are consistent to avoid errors, such as mixing grams with kilograms.
This calculator is widely used in labs, chemistry classrooms, and industrial projects involving chemical mixtures. Common precautions include verifying the molar mass (calculated accurately from the molecular formula), confirming the mass is in grams, and distinguishing between moles and atomic mass correctly.
Frequently asked questions
What is molar mass?
Molar mass is the mass of one mole of a substance, calculated by summing the atomic masses of elements in its molecular formula (in g/mol).
Why is this calculator important?
It enables precise stoichiometric calculations crucial for chemical reactions, solution preparation, and compound analysis.
What happens if I use wrong units?
Results will be incorrect. Always use grams for mass and g/mol for molar mass.
Can I use this calculator for gases?
Yes, as long as the gas's molar mass is correctly provided. Gases like O₂ or N₂ can be calculated using this tool.
How to differentiate moles from atomic mass?
Moles are units of substance quantity, while atomic mass is a relative property of elements expressed in atomic mass units (u).