What this calculator does
Normality is molarity multiplied by the number of reactive equivalents per mole. A 1 mol/L sulfuric acid solution is 2 N, because each molecule supplies two protons.
The awkward feature of normality is that it depends on the reaction, not only on the solution. The same potassium permanganate solution has a different normality in acidic and neutral conditions, because the number of electrons it accepts changes. This context-dependence is why normality has largely been displaced by molarity in modern practice.
The formula
Molarity is multiplied by the n-factor, the number of equivalents per mole of solute. For an acid that is the number of protons donated, for a base the hydroxides accepted, and for a redox reagent the electrons transferred. The n-factor must be determined from the reaction being performed.
| Term | Meaning |
|---|---|
| Normality (N) | Equivalents per litre. |
| Equivalent | The amount reacting with one mole of hydrogen ions or electrons. |
| n-factor | Equivalents per mole, which depends on the reaction. |
| Molarity | Moles per litre, which is reaction-independent and therefore preferred. |
The inputs explained
| Field | What to enter |
|---|---|
| Molarity (mol/L) | Molarity in mol/L. |
| Equivalents per mole (n-factor) | Equivalents per mole. 1 for HCl, 2 for H₂SO₄ fully neutralised, 5 for permanganate in acid. |
When to use it
Titration calculations
At equivalence, normality times volume is equal on both sides, which avoids tracking stoichiometry separately.
Working with older protocols
Many established analytical methods are written in normality and must be followed as published.
Water treatment
Alkalinity and hardness are traditionally expressed in equivalents.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How does the n-factor change normality?
The same molarity with different equivalents per mole.
| Equivalents per mole | Normality | Molarity used | Equivalents per mole used |
|---|---|---|---|
| n = 1 | 1.000 N (eq/L) | 1.000 mol/L | 1 |
| n = 2 | 2.000 N (eq/L) | 1.000 mol/L | 2 |
| n = 3 | 3.000 N (eq/L) | 1.000 mol/L | 3 |
Questions
What is the difference between normality and molarity?
Molarity counts moles of solute; normality counts moles of reactive equivalents. They are equal when the n-factor is 1. Normality depends on the reaction being performed, which makes it convenient for titration arithmetic and ambiguous as a label.
How do I find the n-factor?
From the reaction. For an acid it is the protons actually donated, for a base the hydroxides accepted, and for a redox reagent the electrons transferred. Sulfuric acid is 2 when fully neutralised but 1 if only the first proton reacts.
Why is normality discouraged?
Because the same solution has different normalities in different reactions, so a bottle labelled in normality is ambiguous without knowing the intended use. IUPAC discourages it for this reason, though it persists in titration work and in established analytical standards.
Can I use normality in a titration?
Yes, and it is convenient: at equivalence N₁V₁ equals N₂V₂ regardless of stoichiometry, because the equivalents already account for it. This is the main reason the unit has survived, since it removes a step from the arithmetic.
For the underlying concentration, see the molarity calculator. For the titration itself, see the titration calculator.