Molarity Calculator

Molarity (M) is the number of moles of solute per liter of solution. A 1 M solution contains 1 mole of substance dissolved in enough solvent to make exactly 1 liter total.

Molarity (M) = moles of solute / volume of solution (L)

Common sub-units: mM (10⁻³ M), μM (10⁻⁶ M), nM (10⁻⁹ M). Molarity is the standard unit for concentration in biological research.

Multiply the desired molarity by the volume (in liters) and the molecular weight (g/mol):

mass (g) = molarity (M) × volume (L) × MW (g/mol)

For example, to make 100 mL of 10 mM NaCl (MW = 58.44 g/mol):
mass = 0.01 M × 0.1 L × 58.44 g/mol = 0.058 g = 58.4 mg. Use Calculator 1 above and select your preferred result unit.

Molarity (M) = moles per liter of solution. Molality (m) = moles per kilogram of solvent.

In dilute aqueous solutions they are nearly identical, but molality is preferred for colligative properties because it does not change with temperature. For most bench-side biology work, molarity is the standard.

Molarity and mg/mL are related through molecular weight:

mg/mL = molarity (M) × MW (g/mol)

For example, a 1 mM solution of a 50 kDa protein is: 0.001 M × 50,000 g/mol = 50 mg/mL. For direct unit conversion, use our Concentration Converter.

Three decimal places match the precision of standard laboratory pipettes. Most adjustable pipettes (P2 through P5000) resolve to 0.001 mL (= 1 μL) at best. Showing more digits would imply false precision that cannot be achieved in practice.

Use the unit dropdown next to each result to select your preferred display unit. The "auto" option selects the most readable unit automatically.