Molarity Calculator

Solve molarity, moles, mass or solution volume, plus dilution problems.

About Molarity Calculator

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

Worked example

With the default values below, Molarity Calculator returns Molarity (C) of 1.000000. Change any input above and every figure here is recalculated in your browser.

Inputs used

Modeone of Concentration (C = n/V), Dilution (C₁V₁ = C₂V₂): Concentration (C = n/V)
Solve Forone of Molarity (C), Moles (n), Mass (m), Volume (V): Molarity (C)
Molarity (C)minimum 0 mol/L: 1 mol/L
Moles (n)minimum 0 mol: 1 mol
Molar Mass (MW)accepts 0.1–10,000 g/mol: 58.44 g/mol
Mass of Solute (m)minimum 0 g: 58.44 g
Volume of Solution (V)minimum 0 L: 1 L
Solve For (Dilution)one of Final Concentration (C₂), Final Volume (V₂), Initial Concentration (C₁), Initial Volume (V₁): Final Concentration (C₂)
Initial Concentration (C₁)minimum 0 mol/L: 10 mol/L
Initial Volume (V₁)minimum 0 L: 0.1 L
Final Concentration (C₂)minimum 0 mol/L: 1 mol/L
Final Volume (V₂)minimum 0 L: 1 L

Results

Molarity (C): 1.000000 mol/L
Molarity (mM): 1,000.0000 mM
Moles (n): 1.000000 mol

Step by step

1Moles = mass ÷ molar mass= 1 mol
2Molarity = moles ÷ volume= 1 mol/L = 1000 mM

Assumptions and limits

The result is derived only from the 12 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 6 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

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.