Molarity to Percent Solution Calculator
Convert a molar concentration (mol/L) to weight/volume and weight/weight percent using the solute molar mass and solution density.
How it works
% w/v = M × MW ÷ 10 · % w/w = M × MW ÷ (10 × density) · g/L = M × MW
Molarity times molar mass gives grams of solute per litre of solution. Since weight/volume percent is grams per 100 mL, dividing g/L by 10 converts straight to % w/v. Weight/weight percent instead compares solute mass to total solution mass, so you also divide by the solution density in g/mL — for dilute aqueous solutions where density ≈ 1.0 g/mL, w/v and w/w are nearly identical, but for concentrated or non-aqueous solutions the density correction matters.
Worked example
A 1 M NaCl solution: 1 × 58.44 = 58.44 g/L. That is 58.44 ÷ 10 = 5.844% w/v. At a density of 1.0 g/mL the w/w value is the same, 5.844%.
Frequently asked questions
What is the difference between w/v and w/w?
Weight/volume percent is grams of solute per 100 mL of solution; weight/weight percent is grams of solute per 100 g of solution. They coincide only when the density is exactly 1 g/mL. For syrups, acids and brines the density is well above 1, so w/w is meaningfully smaller than w/v.
Where do I find the solution density?
For dilute aqueous solutions use 1.0 g/mL. For concentrated reagents the density is on the bottle or in a reference table — for example concentrated sulfuric acid is about 1.84 g/mL. Using the right density is essential for an accurate w/w figure.
Does temperature change the result?
Molarity and density both shift slightly with temperature because volume expands when warm. For lab work at room temperature the effect is small, but for precise standards prepare and measure at a stated temperature.
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This calculator is for educational purposes. Double-check important results before acting on them.