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🧉 Molarity Calculator

Solve any part of a solution’s concentration, molarity, mass, molar mass or volume, from M = n/V, with the molar mass auto-filled from a formula.

Mass of solute

7.305 g

M = n/V, with n = mass ÷ molar mass. Volume in litres. 🔒 Computed in your browser.
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How the molarity calculator works

Molarity is moles of solute per litre of solution: M = n/V, where n = mass ÷ molar mass. Enter any three of {mass, molar mass, volume, molarity} and the tool solves for the fourth. Type a chemical formula and the molar mass is computed automatically from atomic weights.

The everyday bench calculation for making up a solution. Enter the formula (e.g. NaCl) and the tool fills in 58.44 g/mol for you, then solves for the mass you need.

Frequently asked questions

How do I calculate molarity?

Molarity (mol/L) = moles of solute ÷ litres of solution, and moles = mass ÷ molar mass. For 5.85 g NaCl (58.44 g/mol) in 1 L: 0.1 mol ÷ 1 L = 0.1 M.

How much solute do I need for a target molarity?

mass = molarity × volume (L) × molar mass. For 0.5 M NaCl in 250 mL: 0.5 × 0.25 × 58.44 = 7.31 g. Enter the target and the tool computes the mass.

Can it find the molar mass for me?

Yes, type the chemical formula and the molar mass is calculated from atomic weights and filled in automatically.

What units does it use?

Molarity in mol/L (M), mass in grams, molar mass in g/mol, and volume in litres (enter mL as 0.25 L, or use the mL field).

What is the difference between molarity and molality?

Molarity is moles per litre of solution; molality is moles per kilogram of solvent. This tool computes molarity (M).

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