Molarity Calculator

Four solvers in one: molarity from moles and volume, moles from molarity and volume, volume from moles and molarity — or molarity straight from a weighed mass using the molar mass (with a built-in formula lookup).

M = mol ÷ L

What do you want to find?

The molarity formula

Definition

M = n ÷ V (molarity = moles of solute ÷ litres of solution)

A “1 M” (one molar) solution contains one mole of solute in each litre of solution. Note the fine print: litres of final solution, not litres of water added — labs use volumetric flasks to hit the total volume exactly.

From a weighed mass

10.0 g of NaCl (58.44 g/mol) is dissolved to make 500 mL of solution. Find the molarity.

moles = 10.0 g ÷ 58.44 g/mol = 0.171 mol
volume = 0.500 L
M = 0.171 ÷ 0.500

Answer: ≈ 0.342 M

Tips for solution problems

Convert mL to L before dividing (250 mL = 0.250 L). This calculator expects litres — the placeholder reminds you.
For mass-based problems, find the molar mass first — the built-in helper accepts a formula like NaCl and fills it in.
Molarity changes slightly with temperature (volume expands); molality (mol/kg solvent) is used when that matters.

Frequently asked questions

What does M mean in chemistry?

Molar: moles of solute per litre of solution. 0.5 M means half a mole per litre.

How do I make a solution of a target molarity?

moles needed = M × V, then grams = moles × molar mass. For 500 mL of 0.2 M NaCl: 0.1 mol × 58.44 g/mol ≈ 5.84 g, dissolved and topped up to 500 mL.

Is molarity the same as concentration?

Molarity is one specific measure of concentration — the most common in chemistry class. Others include molality, mass percent and parts per million.

Related chemistry tools

Dilution Calculator (C₁V₁ = C₂V₂)Solve dilution problems with automatic unit conversion between M, mM, µM and L, mL, µL.Molar Mass CalculatorCalculate the molar mass of any chemical formula with a full element-by-element breakdown and percent composition.pH and pOH CalculatorConvert between pH, pOH, [H⁺] and [OH⁻], and see whether a solution is acidic, basic or neutral.

Learn the concepts

Molarity and Dilution ExplainedLearn molarity (M = mol/L) and dilution (C₁V₁ = C₂V₂) with worked examples, lab-style problems and the unit mistakes to avoid.Molar Mass: Definition and How to Calculate ItWhat is molar mass, and how do you find it? Add up the atomic masses in a formula to get grams per mole. Worked examples for H2O, glucose, Ca(OH)2 and NaCl.