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Molarity Calculator

Solve M = mol/L for molarity, moles, volume or mass of solute. Enter grams with a molar mass or a chemical formula and get the concentration instantly.

0.5
Molarity (mol/L)
0.5
Moles (mol)
1
Volume (L)
29.22
Mass (g)

Molarity

Solved with M = n ÷ V, where n is moles of solute and V is the total volume of the finished solution in litres.

  • 1,000 mL of solution
  • 500 mmol/L
  • Molar mass used: 58.44 g/mol

Molarity is defined per litre of final solution, not per litre of solvent. Dissolve the solute first, then top up to the mark on your volumetric flask.

What is the Molarity Calculator?

Molarity is moles of solute divided by litres of solution. Dissolving 58.44 g of sodium chloride (one mole) and making it up to one litre gives a 1 M solution.

  • Solves for molarity, moles, volume or mass of solute
  • Molar mass from a typed chemical formula
  • Molar, millimolar, micromolar and nanomolar units
  • Litres, millilitres, microlitres and cubic metres
  • Shows the rearranged formula behind every answer
  • Runs entirely in your browser — nothing is uploaded

How to use the Molarity Calculator

  1. 1

    Choose whether you want molarity, moles, volume or mass.

  2. 2

    Say whether the solute is given in moles or as a mass with its molar mass.

  3. 3

    Enter the values you know and pick matching units.

  4. 4

    Optionally type a chemical formula to fill in the molar mass automatically.

  5. 5

    Read the answer and copy the full result if you need it in your notebook.

About the Molarity Calculator

The ByteTools Molarity Calculator solves the concentration equation M = n ÷ V in whichever direction you need. Pick what you are looking for — molarity, moles of solute, solution volume or the mass to weigh out — fill in the values you already have, and the answer appears with the rearranged formula it used.

You can supply the solute as moles, or as a mass in grams together with its molar mass. Type a chemical formula such as NaCl and the tool works out the molar mass for you, so preparing a 0.1 M buffer is a single step rather than three. Millimolar, micromolar and nanomolar units are available for biology work.

All the arithmetic happens locally in your browser with JavaScript. Nothing you type is uploaded or logged, which makes this a safe place to plan an experiment, and the page keeps working with no internet connection.

Frequently asked questions

How do you calculate molarity?

Divide the moles of solute by the volume of the finished solution in litres. Two moles of sugar made up to 4 litres gives 2 ÷ 4 = 0.5 mol/L, written 0.5 M.

How many grams do I need for a 1 M solution?

Multiply the molar mass of the solute by the volume in litres. For 1 M sodium chloride in 500 mL you need 58.44 × 0.5 = 29.22 g. Enter the formula NaCl and the calculator finds the molar mass for you.

What is the difference between molarity and molality?

Molarity is moles per litre of solution and changes slightly with temperature because liquids expand. Molality is moles per kilogram of solvent and is temperature independent. This calculator works in molarity, the unit used for most bench chemistry.

Do I measure the volume before or after dissolving?

After. Molarity is defined per litre of final solution, so dissolve the solute in a smaller volume first, then top up to the mark on a volumetric flask. Adding one litre of water to the solid gives a slightly different concentration.

How do I convert molarity to mg/mL?

Multiply the molarity by the molar mass, then divide by 1000. A 0.25 M solution of glucose, molar mass 180.16 g/mol, is 0.25 × 180.16 = 45.04 g/L, which is 45.04 mg/mL.

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