🧪

Solution Concentration Calculator

Find the molarity of a solution from the mass of solute, its molar mass and the solution volume.

Mass of solute

Molar mass

Solution volume

Loading calculator…

How it works

moles = mass ÷ molar mass · molarity M = moles ÷ litres of solution

This calculator takes you straight from the mass you weighed out to the molarity of the solution. First it converts grams of solute to moles by dividing by the molar mass, then divides those moles by the solution volume in litres. The result is the concentration in moles per litre (M).

Worked example

Dissolving 40 g of sodium hydroxide (molar mass 40 g/mol) to make 1 L of solution: 40 ÷ 40 = 1 mol, and 1 mol ÷ 1 L = 1 mol/L (a 1 M solution).

Sources: Molar concentration — Wikipedia

Frequently asked questions

How is this different from the molarity calculator?

The molarity calculator starts from moles you already know. This one starts from the mass you weighed and its molar mass, doing the grams-to-moles step for you.

Should I use solvent or solution volume?

The total volume of the final solution, measured after the solute has dissolved and been made up to the mark — not the volume of water you started with.

What if I know the desired molarity and need the mass?

Rearrange: mass = molarity × volume × molar mass. For 1 M NaOH in 1 L you would weigh 1 × 1 × 40 = 40 g.

Related calculators

Molarity Calculator

Find molarity from moles or grams, the mass of solute to weigh for a target concentration, or the volume to make — with unit menus (mol/mmol, g/mg, L/mL/µL, M/mM/µM/nM), common lab compounds, mass concentration, normality, a dilution table and the steps.

Dilution Calculator

Use C₁V₁ = C₂V₂ to find how much stock solution to dilute to reach a target concentration and volume.

PPM Concentration Calculator

Work out parts per million from a mass of solute in a solution, convert between ppm, ppb, percent, mg/L, µg/L, g/L, grains per gallon and molarity with a density correction, or convert gas ppm to mg/m³ at any temperature and pressure.

Molar Mass Calculator

Find the molar mass of any compound from its chemical formula, with a per-element mass breakdown.

Moles to Grams Calculator

Convert between moles and grams using molar mass, and see the number of molecules involved.

Educational estimate. Check the formula, units and significant figures for your exact case.