Molarity Calculator

Find solution molarity, moles of solute or solution volume.

Solve for	Molarity
Moles of solute	0.25 mol
Volume of solution	0.5 L

Solve for

Moles of solute

mol

Volume of solution

Molarity

0.5 mol/L

Moles of solute 0.25 mol, Volume of solution 0.5 L.

Moles against volume at 0.5 mol/L (mol up, litres across)

0.25 molat (0.5, 0.25)Point at the chart, or Tab to it and use ← →

0.25 mol: (0.5, 0.25)

About the Molarity Calculator

Choose what to solve for (molarity, moles of solute or volume of solution) and enter the other two. Use it to make up a solution in the lab or to check a chemistry problem.

Molarity (M) is moles of solute per litre of solution, not per litre of solvent. To make a solution, dissolve the solute and then add solvent up to the final volume. To start from grams, divide by molar mass first.

The formula

M = n ÷ V

M: molarity, mol/L
n: moles of solute
V: volume of solution, in litres (mL ÷ 1,000)

Worked example

250 mL of a 0.5 M sodium chloride solution

V = 250 ÷ 1,000 = 0.25 L
n = 0.5 × 0.25 = 0.125 mol
× 58.44 g/mol = 7.31 g of NaCl, made up to 250 mL

Things to keep in mind

Volume must be in litres.
Molarity changes slightly with temperature because volume does.

Questions people ask

Molarity vs molality?

Molality is moles per kg of solvent and doesn't change with temperature.

How do I weigh out the solute?

grams = M × V × molar mass.