Molarity Formula Explained

This reference explains the Molarity formula used by our free Molarity Calculator. Use it to understand variables, units, and common mistakes before you calculate.

The formula

M = moles of solute ÷ volume of solution (L)

Variables and units

• M — Molarity (concentration) (mol/L)
• n — Moles of solute (mol)
• V — Volume of solution (L)

Worked example

Inputs: Dissolve 0.5 mol NaCl in enough water to make 2.0 L solution

1. M = n / V = 0.5 / 2.0 = 0.25 M

Result: Molarity = 0.25 mol/L (0.25 M NaCl)

When to use this formula

Use this formula when you need a quick molarity estimate with values you already know. Our Molarity Calculator applies the same relationship automatically so you can verify handwritten work.

Common mistakes

• Using solvent volume instead of total solution volume
• Forgetting to convert mL to L
• Confusing molarity (M) with molality (m)

Frequently asked questions