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Molarity Calculator

Calculate molarity, moles, or volume for any solution using the M = n/V formula.

What is Molarity Calculator?

The Molarity Calculator solves for molarity (M), moles (n), or volume (V) of a solution using the fundamental chemistry equation M = n / V. It can also convert from mass and molar mass to moles automatically.

How to use

  1. 1 Select what you want to find: Molarity, Moles, or Volume.
  2. 2 Enter the two known values for your chosen mode.
  3. 3 For molarity from mass, enter the mass in grams and the molar mass in g/mol.
  4. 4 Click Calculate to see the result with the formula used.
  5. 5 Use the Molecular Weight Calculator to find the molar mass of your compound.

Formula

M = n / V. n = M × V. V = n / M. Where M is molarity in mol/L, n is moles, and V is volume in liters. Moles from mass: n = mass (g) / molar mass (g/mol).

Example calculation

To make a 0.5 M NaCl solution (molar mass 58.44 g/mol) with 250 mL: moles needed = 0.5 × 0.25 = 0.125 mol. Mass = 0.125 × 58.44 = 7.31 g NaCl.

Frequently asked questions

What is molarity?

Molarity is the number of moles of solute dissolved per liter of solution. A 1 M solution contains 1 mol of solute per liter.

What is the difference between molarity and molality?

Molarity (M) is moles per liter of solution; molality (m) is moles per kilogram of solvent. Molarity changes with temperature; molality does not.

How do I find molar mass?

Use the Molecular Weight Calculator on this site, or look up the compound in a reference. Molar mass equals the sum of atomic weights of all atoms in the formula.

What units does volume need to be in?

Enter volume in liters (L). Convert milliliters by dividing by 1000 (e.g., 250 mL = 0.25 L).

What is a standard solution?

A standard solution is one whose concentration is precisely known, typically prepared by dissolving a precisely weighed amount of a primary standard in a volumetric flask.