Molarity Calculator

Last updated: June 2026

Mode

Moles

mol

Volume

Mass optional

Molar mass optional

g/mol

Molarity

0.5 mol/L

Moles used

0.25 mol

Mass-derived moles

Not used

Formula

M = n / V. n = M x V. V = n / M. Optional moles from mass: n = mass / molar mass.

Common solution references

Solution	Approx. molarity
Concentrated HCl	~12 M
Seawater NaCl	~0.6 M
Blood NaCl	~0.15 M
Vinegar acetic acid	~0.8 M

About this calculator

The Molarity Calculator helps chemistry students and lab learners calculate molar concentration, moles of solute, or solution volume. It also supports moles from mass and molar mass, which is useful when a question gives grams of a compound rather than moles directly.

Molarity formula

Molarity is moles of solute per litre of solution. The same equation can be rearranged to find moles or volume.

M = n / V
n = M x V
V = n / M
n = mass g / molar mass g/mol

How to use the molarity calculator

Choose whether to find molarity, moles, or volume.
Enter the two known values in mol/L, mol, and litres.
If your question gives mass, enter mass and molar mass to calculate moles.
Check that the volume is solution volume, not just solvent added.
Review the main result and the moles used in the calculation.
Use the reference examples to sense-check the concentration.

Worked examples

Find molarity

Input: 0.25 mol dissolved to make 0.5 L solution

Calculation: M = 0.25 / 0.5

Result: 0.5 mol/L

Find moles from mass

Input: 5.85 g NaCl, molar mass 58.44 g/mol

Calculation: n = 5.85 / 58.44

Result: About 0.100 mol

Molarity vs molality

Molarity uses litres of solution. Molality uses kilograms of solvent. They are not the same, especially when temperature or density changes matter.

Making a molar solution

A typical lab method is to weigh the solute, dissolve it in some solvent, transfer it to a volumetric flask, then make the final solution up to the mark.

Chemistry education disclaimer

This calculator is for educational chemistry use. Real lab work should follow local safety rules, solution-preparation procedures, purity corrections, and teacher or supervisor guidance.

Frequently asked questions

What does molarity mean?

Molarity is moles of solute per litre of solution.

What unit is molarity measured in?

It is usually written as mol/L or M.

Can I use grams instead of moles?

Yes, if you also know the molar mass. The calculator converts grams to moles first.

Is volume measured before or after dissolving?

Molarity uses the final solution volume.

Does temperature matter?

Temperature can affect solution volume, so precise lab work should control temperature.

Related calculators

molecular-weight-calculator
concentration-calculator
ph-calculator

What does this mean?

This calculator is designed to help you understand the likely number before you make a decision or start an application.

Your result should be checked against official UK guidance, especially if your circumstances include dependants, exemptions, prior leave, or a complex immigration history.

Treat the figure as a planning tool rather than legal advice. Where the answer affects an application deadline or major payment, speak to an authorised adviser.