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Molarity calculator

Compute the molar concentration of a solution from moles and volume.

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Enter Moles (mol), Volume (L) and the Molarity calculator works out Molarity (mol/L) straight away. For instance, with Moles (mol) = 0.5 and Volume (L) = 2 it returns Molarity (mol/L) = 0.25.

How to use it

  1. Enter your values: Moles (mol), Volume (L).
  2. Read the result instantly: Molarity (mol/L).

Frequently asked questions

How does the Molarity calculator work?

It takes Moles (mol) and Volume (L) and derives Molarity (mol/L) from them. The calculation is live as you type, so the result updates on every change.

Which values does the calculator ask for?

2 values: Moles (mol) and Volume (L). Nothing else is required — no account, no file upload.

What does a typical calculation look like?

With Moles (mol) = 0.5 and Volume (L) = 2, the calculator returns Molarity (mol/L) = 0.25. Those figures come from running this exact tool, so you can reproduce them by entering the same values.

How much does the result change with different inputs?

It moves a lot. Using Moles (mol) = 1 and Volume (L) = 2.2 instead, Molarity (mol/L) goes from 0.25 to 0.455 — which is why it is worth testing a few scenarios rather than trusting a single figure.

What does it give for smaller values?

Scaled down to Moles (mol) = 0.25 and Volume (L) = 1.8, Molarity (mol/L) comes out at 0.139. The relationship is worth checking at both ends before you rely on a single result.

When would I actually use this?

Preparing a solution at a stated concentration, working out how much of a reagent a reaction needs, and converting between mass, moles and volume.

What is the most common mistake?

Confusing molarity with molality. One is per litre of solution and the other per kilogram of solvent; they diverge as concentration rises, and only one of them is temperature-independent.

What is the difference between the Molarity calculator and the Ideal gas law calculator?

This one returns Molarity (mol/L); the Ideal gas law calculator returns Pressure (atm). That is the whole difference — open the one whose figure you need.

Is there a tool for the next step?

Normality calculator is the closest one after this: Compute the normality of a solution — gram-equivalents of solute per litre. Enter equivalents directly or a mass with its molar mass and n-factor, plus the volume, and it returns the normality (N) and the equivalent molarity (M = N ÷ n-factor).

What else is worth having open alongside it?

Titration calculator and Dilution calculator (C1V1 = C2V2) — they come up in the same task often enough to be worth a second tab.

Further reading

All guides →
ExplainerMolarity Is per Litre of Solution, Not per Litre of Water0.5 mol in 2 litres is 0.25 mol/L. The two litres have to be the finished solution — adding solute to two litres of water gives something else, and the label will be wrong.ExplainerOsmotic Pressure Counts Particles, Not Molecules0.15 M of a salt that splits in two and 0.30 M of one that does not give the identical 7.64 atmospheres. Only the particle count reaches the membrane.ExplainerThe Same Burette Reading Gives Two Different Concentrations24.80 mL of 0.1 M titrant into 25.00 mL of analyte gives 0.0992 M — or 0.0496 M if the analyte releases two protons. The stoichiometry is typed, not measured.How-toHow to Calculate a Dilution with C1V1 = C2V2Solve for the missing term, then convert the answer into a bench instruction. The step almost everyone skips is that the solvent you add is V2 minus V1, not V2.How-toHow to Calculate pH — And When the Weak-Acid Shortcut Stops WorkingFour routes for four kinds of solution, each worked with real numbers. Including the part most pages leave out: the square-root formula for a weak acid is an approximation with a validity limit, and it fails quietly.ExplainerA Buffer Holds Its pH by a Ratio, So Dilution Changes NothingEqual amounts of a weak acid and its base give pH = pKa exactly, at any concentration. Blood runs the same equation at a 20:1 ratio and lands on 7.40.