Normality Calculator (Equivalents per Litre, N)
By Santaji GadepatilinUpdated November 4, 2026
Normality counts reactive equivalents per litre — protons for an acid, hydroxide ions for a base, electrons for a redox reagent — so a 1 N acid exactly neutralises the same volume of a 1 N base. This normality calculator works out normality and molarity from the mass you weigh out, or the mass needed for a target N.
How to use the normality calculator
Enter the mass of solute, its molar mass, the equivalents per mole and the final solution volume. The calculator returns the molarity, normality and equivalent weight. To find how much to weigh out, clear the mass and enter the normality you want.
Normality formula
N = M × n = (m ÷ EW) ÷ V · EW = molar mass ÷ n
Example
4.904 g of sulfuric acid (98.079 g/mol, n = 2) made up to 500 mL:
- Molarity = 4.904 ÷ 98.079 ÷ 0.500 = 0.1000 mol/L
- Normality = 0.1000 × 2 = 0.2000 N
- Equivalent weight = 98.079 ÷ 2 = 49.039 g/eq
Equivalent weights of common reagents
| Reagent | Molar mass (g/mol) | n (basis) | Equivalent weight (g/eq) | Mass for 1 L of 1 N |
|---|---|---|---|---|
| Hydrochloric acid (HCl) | 36.46 | 1 (acid–base) | 36.460 | 36.460 g |
| Sulfuric acid (H₂SO₄) | 98.079 | 2 (acid–base) | 49.039 | 49.039 g |
| Phosphoric acid (H₃PO₄) | 97.994 | 3 (full neutralisation) | 32.665 | 32.665 g |
| Sodium hydroxide (NaOH) | 39.997 | 1 (acid–base) | 39.997 | 39.997 g |
| Calcium hydroxide (Ca(OH)₂) | 74.093 | 2 (acid–base) | 37.047 | 37.047 g |
| Sodium carbonate (Na₂CO₃) | 105.988 | 2 (to CO₂) | 52.994 | 52.994 g |
| Oxalic acid dihydrate (H₂C₂O₄·2H₂O) | 126.065 | 2 (acid–base or redox) | 63.032 | 63.032 g |
| Potassium permanganate (KMnO₄) | 158.034 | 5 (redox, acid solution) | 31.607 | 31.607 g |
| Potassium dichromate (K₂Cr₂O₇) | 294.185 | 6 (redox, acid solution) | 49.031 | 49.031 g |
Notes
- In a titration at the end point, N₁V₁ = N₂V₂ — see the titration calculator.
- To dilute a stock solution, the dilution calculator works the same way with normality as with molarity.
Frequently asked questions
What is the formula for normality?
N = (mass ÷ equivalent weight) ÷ volume in litres, where equivalent weight = molar mass ÷ n. Equivalently, N = molarity × n.
What is the difference between normality and molarity?
Molarity counts moles per litre; normality counts reacting equivalents per litre. 1 M H₂SO₄ is 2 N because each molecule gives two H⁺ ions, while 1 M HCl is 1 N.
How do I make 1 L of 0.1 N H₂SO₄?
The equivalent weight is 98.079 ÷ 2 = 49.04 g/eq, so 0.1 N needs 4.904 g per litre. In practice it is made by diluting concentrated acid and standardised by titration.
Why is normality used less today?
Because n depends on the reaction — KMnO₄ transfers 5 electrons in acid but 3 in neutral solution — the same solution can have two normalities. IUPAC recommends molarity, but normality remains common in titration and water-testing methods.