Molarity Calculator
Calculate molarity (mol/L) from solute mass, molar mass, and solution volume. Find grams needed for a target concentration, or volume from mass and molarity.
g
g/mol
L
Molarity
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Millimoles of Solute —
Mass Concentration —
Extended More scenarios, charts & detailed breakdown ▾
g
g/mol
L
Molarity
—
Moles of Solute —
Mass Concentration —
Professional Full parameters & maximum detail ▾
g
g/mol
L
Concentration Measures
Molarity (M) —
Molality (m) —
Normality (N) —
Mass Concentration —
PPM (mg/L) —
Advanced
Osmolarity —
Stock Volume for Dilution —
Stock Volume (mL) —
How to Use This Calculator
- Enter the solute mass in grams.
- Enter the molar mass (g/mol) — use the Molar Mass Calculator if needed.
- Enter the solution volume in liters.
- Click Calculate to get molarity, millimoles, and mass concentration.
- Use the Extended tabs to find required mass or volume for a target molarity.
Formula
Molarity (M) = moles ÷ volume (L) = (mass ÷ molar mass) ÷ volume
Mass concentration (g/L) = Molarity × Molar Mass
Millimoles = Moles × 1000
Example
Example: 5.85 g NaCl (MW = 58.44 g/mol) in 0.5 L → moles = 0.100 mol → M = 0.200 mol/L, mass concentration = 11.7 g/L.
Frequently Asked Questions
- Molarity (M) is the number of moles of solute per liter of solution. It is the most common way to express concentration in chemistry: M = moles ÷ liters.
- First divide the mass (g) by the molar mass (g/mol) to get moles, then divide by volume in liters: M = (mass ÷ molar mass) ÷ volume.
- Molarity (M) is moles per liter of solution; molality (m) is moles per kilogram of solvent. Molality does not change with temperature, making it useful for boiling/freezing point calculations.
- Dissolve 1 mole of solute (its molar mass in grams) in enough solvent to make exactly 1 liter of solution. For example, 58.44 g of NaCl (MW = 58.44 g/mol) in 1 L gives a 1 M NaCl solution.
- Normality (N) = Molarity × equivalents per mole. For a diprotic acid like H₂SO₄, N = 2 × M. It reflects reactive capacity rather than just concentration.