Molality Calculator
Calculate the molality of a solution — its concentration in moles of solute per kilogram of solvent. Enter the moles of solute directly, or enter the mass and molar mass, then enter the mass of solvent.
Amount of solute
Mass of solvent
Molality vs Molarity
Molality (m) is the number of moles of solute per kilogram of solvent. Unlike molarity, it is based on mass, not volume, so it does not change with temperature.
Use molality for properties that depend on temperature, such as boiling-point elevation and freezing-point depression.
Formula
m = moles of solute ÷ kilograms of solvent
Example: Molality of 0.5 mol solute in 1 kg of solvent:
0.5 ÷ 1 = 0.5 mol/kg