About the Normality Calculator
This normality calculator works with the concentration unit most used in titrations: equivalents of reactive species per liter. Pick a common acid, base or redox reagent — or enter your own molar mass and equivalents per mole — then calculate normality from a weighed mass and volume, convert molarity to normality, or find how many grams to dissolve to prepare a solution of a target normality.
It is meant for analytical chemistry students, lab technicians preparing standard solutions, and water-treatment or QC staff who still see normality on methods and reagent bottles. The equivalent weight and number of equivalents are shown so you can check the working by hand.
Normality depends on the reaction: sulfuric acid is 2 N per mole when both protons react, and permanganate counts 5 electrons in acidic solution but 3 in neutral solution. The presets assume complete neutralisation (acids and bases) or the acidic-solution half-reaction (oxidisers); use Custom if your reaction differs.
With the default inputs, the answer is 0.19985. Change any value above to recalculate instantly.
How to use the normality calculator
- 1Choose what to calculate: normality from mass, from molarity, or the mass needed.
- 2Select the solute, or choose Custom and enter its molar mass and n-factor.
- 3Enter the mass, molarity or target normality.
- 4Enter the final solution volume in milliliters.
- 5Read the normality or grams to weigh, plus the equivalent weight for your notes.
Formula and method
Normality counts reactive units rather than whole molecules. The n-factor is the number of protons an acid donates, hydroxide ions a base supplies, or electrons an oxidising or reducing agent transfers per formula unit. Dividing the molar mass by n gives the equivalent weight — the mass that supplies one equivalent — and normality is equivalents per liter of solution.
So normality is simply molarity multiplied by n. From a weighed mass, N = mass ÷ (equivalent weight × volume in liters); to prepare a solution, rearrange to mass = N × V × equivalent weight. Because equivalents react one-to-one, titrations obey N₁V₁ = N₂V₂ regardless of stoichiometry.
- N
- Normality (equivalents per liter)
- M
- Molarity (moles per liter)
- n
- Equivalents per mole (n-factor)
- Eq. wt
- Equivalent weight (g/eq)
- V
- Solution volume (L)
Worked examples
4.9 g H₂SO₄ in 500 mL
Sulfuric acid gives 2 H⁺, so its equivalent weight is 98.072 ÷ 2 = 49.036 g/eq. 4.9 g ÷ 49.036 = 0.0999 eq in 0.5 L gives 0.1999 N — about 0.2 N, or 0.1 M.
0.5 M phosphoric acid to normality
Phosphoric acid can donate three protons when fully neutralised, so N = 0.5 × 3 = 1.5 N.
Prepare 1 L of 0.1 N sodium carbonate
Na₂CO₃ accepts 2 H⁺ when titrated to CO₂, so its equivalent weight is 105.988 ÷ 2 = 52.994 g. For 0.1 eq/L in 1 L, weigh 0.1 × 52.994 = 5.299 g.
0.79 g KMnO₄ in 250 mL (acidic titrations)
In acidic solution MnO₄⁻ gains 5 electrons, so the equivalent weight is 158.032 ÷ 5 = 31.606 g. 0.79 g ÷ 31.606 ÷ 0.25 L ≈ 0.100 N.
Frequently asked questions
What is normality in chemistry?+
Normality (N) is the number of gram equivalents of solute per liter of solution. An equivalent is the amount that donates or accepts one mole of H⁺, OH⁻ or electrons in the reaction being considered.
How do you convert molarity to normality?+
Multiply molarity by the n-factor: N = M × n. For example 1 M H₂SO₄ is 2 N when both protons react, while 1 M HCl is 1 N because HCl has only one acidic proton.
What is equivalent weight?+
Equivalent weight is the molar mass divided by the n-factor: the mass of substance that supplies one equivalent. For sulfuric acid it is 98.07 ÷ 2 = 49.04 g/eq; for NaOH it equals the molar mass, 40.00 g/eq.
Why is normality used in titrations?+
Equivalents always react one-to-one, so at the endpoint N₁V₁ = N₂V₂ no matter what the mole ratio of the balanced equation is. That makes normality convenient for acid–base and redox titrations.
Why can the same solution have different normalities?+
Normality depends on the reaction. Phosphoric acid can be 1, 2 or 3 N per mole depending on how many protons are titrated, and KMnO₄ is 5 N per mole in acid but 3 N per mole in neutral solution. IUPAC discourages normality for this reason.