Normality Calculator
Normality (N) is the concentration unit of titrations: equivalents of solute per litre of solution. This calculator finds normality from mass and equivalent weight, computes equivalent weight from molar mass and n (equivalents per mole), converts between normality and molarity (N = M × n), and solves N₁V₁ = N₂V₂ dilutions — all in your browser, nothing uploaded.
Scope: normality (N) and equivalent weight for titrations. For mass-based ppm/ppb ⇄ molarity use the ppm to molarity calculator; for mole ratios in balanced equations use the molar ratio calculator. Bridge formula: N = M × nequivalents — use N when the reaction stoichiometry (titration) matters, M when counting molecules.
The formulas
equivalents = mass (g) / equivalent weight (g/eq)
N = equivalents / volume (L) = mass / (EW × VL)
equivalent weight = molar mass / n
N = M × n · M = N / n
N₁V₁ = N₂V₂ (dilution — volumes in the same unit)
n is the number of equivalents per mole and depends on the reaction: replaceable H⁺ for acids, OH⁻ for bases, total ionic charge for salts, electrons transferred for redox. Pick the wrong n and the normality is wrong — the table below gives verified n values.
Equivalent weight table — verified n values
Molar masses from standard atomic weights; n verified against analytical-chemistry references (see FAQ). EW = M / n.
| Compound | Formula | Class | n | M (g/mol) | EW (g/eq) |
|---|
| Hydrochloric acid | HCl | acid | 1 | 36.458 | 36.458 |
| Nitric acid | HNO₃ | acid | 1 | 63.012 | 63.012 |
| Acetic acid | CH₃COOH | acid | 1 | 60.052 | 60.052 |
| Sulfuric acid | H₂SO₄ | acid | 2 | 98.072 | 49.036 |
| Oxalic acid (acid) | H₂C₂O₄ | acid | 2 | 90.034 | 45.017 |
| Carbonic acid | H₂CO₃ | acid | 2 | 62.024 | 31.012 |
| Phosphoric acid | H₃PO₄ | acid | 3 | 97.994 | 32.665 |
| Sodium hydroxide | NaOH | base | 1 | 39.997 | 39.997 |
| Potassium hydroxide | KOH | base | 1 | 56.105 | 56.105 |
| Ammonium hydroxide | NH₄OH | base | 1 | 35.046 | 35.046 |
| Calcium hydroxide | Ca(OH)₂ | base | 2 | 74.092 | 37.046 |
| Barium hydroxide | Ba(OH)₂ | base | 2 | 171.341 | 85.671 |
| Aluminium hydroxide | Al(OH)₃ | base | 3 | 78.003 | 26.001 |
| Sodium chloride | NaCl | salt | 1 | 58.440 | 58.440 |
| Potassium chloride | KCl | salt | 1 | 74.548 | 74.548 |
| Calcium chloride | CaCl₂ | salt | 2 | 110.978 | 55.489 |
| Sodium carbonate | Na₂CO₃ | salt | 2 | 105.988 | 52.994 |
| Potassium permanganate (acidic) | KMnO₄ | redox | 5 | 158.032 | 31.606 |
| Potassium permanganate (basic) | KMnO₄ | redox | 3 | 158.032 | 52.677 |
| Potassium dichromate | K₂Cr₂O₇ | redox | 6 | 294.181 | 49.030 |
| Hydrogen peroxide (redox) | H₂O₂ | redox | 2 | 34.014 | 17.007 |
| Oxalic acid (reductant) | H₂C₂O₄ | redox | 2 | 90.034 | 45.017 |
| Ferrous sulfate (Fe²⁺→Fe³⁺) | FeSO₄ | redox | 1 | 151.901 | 151.901 |
| Sodium thiosulfate (iodometry) | Na₂S₂O₃ | redox | 1 | 158.097 | 158.097 |
Values computed from IUPAC conventional atomic weights and the n rules above (Decimal arithmetic in the tool oracle). Redox n values assume the stated medium/reaction — e.g. KMnO₄ in strongly acidic titration (Mn⁺⁷ → Mn²⁺, 5 e⁻). Analytical labs usually weigh oxalic acid dihydrate (H₂C₂O₄·2H₂O, EW = 63.033 g/eq) as the primary standard; see the worked example.
Worked examples
Example 1 — Normality from mass
Dissolve 49.04 g H₂SO₄ (EW = 49.04 g/eq) and dilute to 1 L.
Equivalents = 49.04 / 49.04 = 1.0000 eq; N = 1.0000 / 1 = 1.000 N.
Example 2 — Molarity to normality
1.000 M H₂SO₄, diprotic acid so n = 2.
N = 1.000 × 2 = 2.000 N.
Example 3 — Equivalent weight
Sulfuric acid: M = 98.072 g/mol, n = 2.
EW = 98.072 / 2 = 49.036 g/eq.
Example 4 — Dilution
Dilute 250 mL of 2 N stock to 1 L.
N₂ = (2 × 0.25) / 1 = 0.500 N.
Example 5 — Weighing a standard solution
Prepare 250 mL of 0.1 N oxalic acid from the dihydrate (EW = 63.033 g/eq).
Mass = 0.1 × 63.033 × 0.25 = 1.5758 g.
Normality: FAQ
What is normality in chemistry?
Normality, written N, is a concentration unit: the number of equivalents of solute per litre of solution. One equivalent is the amount of a substance that supplies or reacts with one mole of the reactive unit of the reaction, such as one mole of H+ in an acid-base titration. The defining relation is N equals equivalents divided by volume in litres.
What is the formula for normality?
Normality equals mass in grams divided by the product of equivalent weight and volume in litres: N = (mass / EW) / V. Equivalently, first compute equivalents as mass / EW, then divide by the volume in litres. Example: 49.04 g of sulfuric acid with an equivalent weight of 49.04 g per equivalent dissolved in 1 litre gives exactly 1.000 N.
What is equivalent weight and how do I calculate it?
Equivalent weight is the mass of a substance that supplies one equivalent: EW = molar mass / n, where n is the number of equivalents per mole. For sulfuric acid, molar mass 98.072 g/mol and n = 2 gives EW = 49.036 g/eq. The n value depends on the reaction type, which is why the equivalent weight calculator on this page asks for it.
How do I find n, the number of equivalents per mole?
For acids, n is the number of replaceable hydrogen ions: HCl n = 1, H2SO4 n = 2, H3PO4 n = 3. For bases, n is the number of hydroxide ions: NaOH n = 1, Ca(OH)2 n = 2. For salts, n is the total ionic charge: NaCl n = 1, CaCl2 n = 2. For redox reactions, n is the number of electrons transferred: KMnO4 in acid n = 5, in basic solution n = 3, K2Cr2O7 n = 6. The table on this page lists verified n values for 24 common compounds.
What is the difference between normality and molarity?
Molarity counts molecules per litre; normality counts reactive units per litre. They are linked by N = M times n. For NaOH with n = 1, 1 M equals 1 N. For H2SO4 with n = 2, 1 M equals 2 N. Normality is reaction-specific: the same KMnO4 solution has different normality in acidic versus basic titrations because n changes.
When should I use normality instead of molarity?
Use normality for titrations, especially acid-base and redox titrimetry. At the equivalence point, N1 times V1 equals N2 times V2 for any pair of reactants, with no balanced equation needed. That is the practical payoff: one normality scale works across different stoichiometries, while molarity requires the mole ratio from the balanced equation.
How do I prepare 1 litre of 1 N sulfuric acid?
Weigh 49.04 g of concentrated H2SO4 equivalent, i.e. one equivalent weight, add it slowly to about 700 mL of distilled water with stirring and cooling, then dilute to exactly 1 litre in a volumetric flask. Safety: always add acid to water, never water to acid, and wear eye protection. In practice, labs standardise the solution by titration because concentrated acid strength varies.
What is the normality of 1 M sodium hydroxide?
1 N. NaOH supplies one hydroxide ion per formula unit, so n = 1 and N = M times n = 1 times 1 = 1 N. Whenever n = 1, normality and molarity are numerically identical.
Why does potassium permanganate have two different n values?
Because n counts electrons transferred, which depends on the medium. In acidic solution manganese goes from +7 to +2, a 5-electron change, so n = 5 and EW = 158.032/5 = 31.606 g/eq. In basic solution it goes from +7 to +4, a 3-electron change, so n = 3 and EW = 52.677 g/eq. Always state the medium when reporting KMnO4 normality.
How do I dilute a normal solution?
Use N1 times V1 equals N2 times V2 with both volumes in the same unit. Example: to make 1 litre of 0.5 N from 2 N stock, V1 = (0.5 times 1)/2 = 0.25 L, so measure 250 mL of the 2 N stock and dilute to 1 litre. The dilution tab on this page solves for any one of the four quantities.
Can normality be larger than molarity?
Yes, whenever n is greater than 1. A 1 M H2SO4 solution is 2 N, and 0.1 M K2Cr2O7 is 0.6 N. When n equals 1 the two are equal, and normality can never be smaller than molarity for a valid n. A normality quoted without stating n, or the reaction it refers to, is ambiguous.
What are the units of normality?
Equivalents per litre, eq/L, written simply as N. A 0.1 N solution is also called decinormal and written N/10; 0.01 N is centinormal, N/100. Normality is a concentration, so it always refers to a stated volume of solution, not of solvent.
Is normality still used by chemists?
IUPAC discourages normality in favour of molarity, but it remains standard wherever titrations dominate: analytical labs, pharmacopeia assays, and water and wastewater analysis. If a procedure says titrate with 0.1 N NaOH, it means a solution standardised to 0.1 equivalents per litre, and this calculator converts it to any other unit you need.
How do I convert 0.5 N H2SO4 to molarity?
Divide by n. For sulfuric acid as a diprotic acid n = 2, so M = 0.5/2 = 0.25 M. In general M = N/n and N = M times n; the conversion tab on this page does both directions.
Worked example: what is the normality of 4.9 g H2SO4 in 500 mL?
Equivalents = 4.9 / 49.04 = 0.09992 eq. Volume = 0.5 L, so N = 0.09992 / 0.5 = 0.1998 N. This is the Mode 1 calculation: mass divided by equivalent weight gives equivalents, divided by litres gives normality.