Molarity Calculator
Solve molarity, moles, mass or solution volume, plus dilution problems.
Inputs
Use the Molecular Weight Calculator to find this.
Molarity (C)
1.000000mol/L
Result
0.000000
Molarity (mM)
1,000.0000mM
Moles (n)
1.000000mol
Step by step
Moles = mass ÷ molar mass
58.44 g ÷ 58.44 g/mol
= 1 mol
Molarity = moles ÷ volume
1 mol ÷ 1 L
= 1 mol/L = 1000 mM
How it works
Molarity (C) is the amount of solute in moles divided by the volume of solution in litres. It relates to mass via the molar mass: C = m / (MW × V). For dilution problems, the moles of solute are conserved: C₁V₁ = C₂V₂. You can solve for any unknown given three known quantities.
Formulas
Molarity
Molarity = moles ÷ volume = mass ÷ (molar mass × volume)
- C
- Molarity (mol/L)
- n
- Amount of substance (mol)
- V
- Volume (L)
- m
- Mass of solute (g)
- M_W
- Molar mass (g/mol)
Dilution
Initial concentration × Initial volume = Final concentration × Final volume
- C₁
- Initial concentration
- V₁
- Initial volume
- C₂
- Final concentration
- V₂
- Final volume
Frequently Asked Questions
What is the molar mass of NaCl?
NaCl: Na = 22.990 g/mol + Cl = 35.45 g/mol = 58.44 g/mol. This is the default value in the calculator. Use the Molecular Weight Calculator for other compounds.
What does 1 M mean?
1 M (1 molar) means 1 mole of solute per litre of solution. For NaCl, that's 58.44 g dissolved and made up to 1 L of solution.
How do I prepare 100 mL of 0.1 M HCl from 12 M stock?
Use the dilution formula: V₁ = C₂V₂/C₁ = (0.1 × 0.1) / 12 = 0.00083 L = 0.83 mL. Add 0.83 mL of 12 M HCl to a flask, then make up to 100 mL with water. Always add acid to water, not water to acid.
What is the difference between molarity and molality?
Molarity (M) is moles per litre of solution; it changes with temperature because liquid volume changes. Molality (m) is moles per kilogram of solvent; it's temperature-independent. Molarity is more common in general chemistry; molality is preferred for colligative properties.