Our Molarity Calculator helps you find the molar concentration of a solution instantly. Enter any two values — moles of solute, volume of solution, or molarity — and get the third calculated automatically.
Molarity Calculator
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Molarity Formula
M = n / V — where M is molarity (mol/L), n is moles of solute, and V is volume of solution in litres.
What is Molarity?
Molarity (M) is the number of moles of a solute dissolved in one litre of solution. It is the most common unit of concentration used in chemistry labs, medicine, and industry.
How to Calculate Molarity — Step by Step
- Find the moles of solute: divide mass (g) by molar mass (g/mol).
- Measure the volume of the solution in litres.
- Divide: M = moles ÷ volume.
Example: Dissolve 5.85 g of NaCl (molar mass 58.5 g/mol) in 500 mL of water.
Moles = 5.85 / 58.5 = 0.1 mol
Volume = 0.5 L
Molarity = 0.1 / 0.5 = 0.2 mol/L
Molarity Reference Table
| Solution | Typical Molarity |
|---|---|
| Seawater (NaCl) | 0.6 M |
| Blood plasma (Na+) | 0.14 M |
| Household vinegar (acetic acid) | 0.83 M |
| Concentrated HCl | 12 M |
| Saturated NaCl | 6.1 M |
Molarity vs Molality vs Normality
- Molarity (M): moles of solute per litre of solution — most common in labs.
- Molality (m): moles of solute per kg of solvent — used when temperature changes.
- Normality (N): equivalents of solute per litre — used in acid-base and redox chemistry.
FAQs
What unit is molarity measured in?
Molarity is measured in mol/L, also written as M (capital M). 1 M = 1 mole per litre.
How do I convert grams to moles?
Divide the mass in grams by the molar mass of the substance (found on the periodic table or molecular formula). Moles = mass (g) / molar mass (g/mol).
Is molarity the same as concentration?
Molarity is one way to express concentration. Concentration can also be expressed as mass/volume (g/L), percentage, or parts per million (ppm).
What is the formula for molarity?
Molarity (M) = moles of solute ÷ volume of solution in litres. Rearranged, moles = M × volume, and volume = moles ÷ M.