Molarity calculator
M = n / V — fill every field except the one you want to solve for.
Leave blank to derive moles from mass instead.
Used only when moles is left blank.
Fill in every field except the one you are solving for — the result appears here.
Formula and how to use it
Molarity (M) is the number of moles of solute dissolved per litre of solution: M = n / V, where n is moles and V is volume in litres. Rearranged, n = M × V and V = n / M. When you only have a mass, convert it first: n = mass ÷ molar mass.
A 0.5 M sodium chloride solution therefore contains 0.5 mol (about 29.2 g) of NaCl per litre. Because volume changes with temperature, molarity is technically temperature-dependent; for precise work at temperatures far from 25 °C, molality (mol per kg of solvent) is preferred, but molarity remains the standard unit for most laboratory solutions.
This calculator solves for molarity, moles, volume, or mass from the other known values, and always keeps the arithmetic visible so you can check the result against your own working.