Normality Calculator
Calculate the normality of a solution from the mass dissolved or from its molarity, or find how much solid or concentrated acid you need to make a solution of a given normality. Common acids, bases and redox reagents are built in with their equivalent weights.
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H⁺ for acids, OH⁻ for bases, electrons for redox
Overrides molar mass ÷ n if filled
Blank = typical bottle value for the chosen acid/base
Blank = typical value (e.g. HCl 37% = 1.19)
Leave the value to solve for empty
How to use the Normality Calculator
- Choose a task: calculate normality from mass or molarity, prepare a solution from a solid or a concentrated liquid, or dilute.
- Pick the substance. The equivalent weight and n-factor fill in automatically; choose Other to enter your own molar mass and n-factor.
- Enter the amounts: mass, volume, molarity or target normality, depending on the task.
- Press Calculate to see the result with the formula and your numbers.
- Use the preparation table for other common strengths, or Copy the recipe for your lab notebook.
Normality formulas
- Equivalent weight: E = M ÷ n, where M is the molar mass (g/mol) and n is the n-factor (eq/mol).
- Normality from mass: N = m ÷ (E × V), with m in grams and V in liters.
- Normality from molarity: N = M × n.
- Mass to prepare: m = N × V × E.
- Stock normality: N = (% w/w ÷ 100) × density (g/mL) × 1000 ÷ E.
- Dilution: N₁ × V₁ = N₂ × V₂, because the number of equivalents does not change.
Equivalent weights of common reagents
| Reagent | Molar mass (g/mol) | n-factor | Equivalent weight (g/eq) | Mass for 1 L of 0.1 N |
|---|---|---|---|---|
| Sodium hydroxide, NaOH | 40.00 | 1 | 40.00 | 4.000 g |
| Sodium carbonate, Na₂CO₃ | 105.99 | 2 | 53.00 | 5.300 g |
| Oxalic acid dihydrate | 126.07 | 2 | 63.04 | 6.304 g |
| Potassium hydrogen phthalate | 204.22 | 1 | 204.22 | 20.422 g |
| Potassium permanganate (acidic) | 158.03 | 5 | 31.61 | 3.161 g |
| Potassium dichromate | 294.18 | 6 | 49.03 | 4.903 g |
| Sodium thiosulfate pentahydrate | 248.18 | 1 | 248.18 | 24.818 g |
| Silver nitrate | 169.87 | 1 | 169.87 | 16.987 g |
Concentrated reagents
| Reagent | Typical % w/w | Density (g/mL) | Molarity | Normality | mL per 1 L of 1 N |
|---|---|---|---|---|---|
| Hydrochloric acid | 37% | 1.19 | 12.1 M | 12.1 N | 82.8 mL |
| Sulfuric acid | 98% | 1.84 | 18.4 M | 36.8 N | 27.2 mL |
| Nitric acid | 70% | 1.42 | 15.8 M | 15.8 N | 63.4 mL |
| Phosphoric acid | 85% | 1.685 | 14.6 M | 43.9 N | 22.8 mL |
| Acetic acid (glacial) | 99.7% | 1.049 | 17.4 M | 17.4 N | 57.4 mL |
| Ammonia solution | 28% NH₃ | 0.90 | 14.8 M | 14.8 N | 67.6 mL |
Bottle concentrations vary by supplier and grade; use the values on your label. Solutions made from concentrated acids should be standardized by titration against a primary standard such as sodium carbonate or KHP.
Lab tips
- Add acid to water, slowly and with stirring, never the other way around. Dilution of sulfuric acid releases a lot of heat.
- Make up to volume in a volumetric flask after the solute has dissolved and cooled; do not simply add the calculated volume of water.
- Check the reaction. Phosphoric acid titrated only to its first endpoint has n = 1, not 3, and permanganate in neutral solution gains 3 electrons, not 5.
- NaOH absorbs water and CO₂ from the air, so a weighed NaOH solution should be standardized before precise work.
Frequently asked questions
What is normality?
Normality (N) is the number of gram equivalents of solute per liter of solution. One equivalent is the amount that supplies or reacts with one mole of H⁺ ions (acid-base), one mole of electrons (redox) or one mole of unit charge (precipitation).
How do you calculate normality?
Divide the equivalents of solute by the volume in liters: N = (mass ÷ equivalent weight) ÷ V. The equivalent weight is the molar mass divided by the n-factor. For example, 4.904 g of H₂SO₄ (E = 49.04 g/eq) in 0.5 L gives 0.1 eq ÷ 0.5 L = 0.2 N.
How do you convert molarity to normality?
Multiply the molarity by the n-factor: N = M × n. A 0.5 M sulfuric acid solution has n = 2, so it is 1 N. For HCl and NaOH, n = 1, so normality equals molarity.
What is the n-factor?
The n-factor is the number of equivalents per mole. For acids it is the number of replaceable H⁺ ions, for bases the number of OH⁻ ions (or H⁺ accepted), for redox reagents the electrons gained or lost per formula unit (5 for KMnO₄ in acid, 6 for K₂Cr₂O₇) and for salts the total positive charge.
How do I make 1 N HCl from concentrated HCl?
Concentrated hydrochloric acid is about 37% w/w with a density of 1.19 g/mL, which is about 12.1 N. For 1 L of 1 N HCl, measure about 82.8 mL of the concentrated acid, add it slowly to roughly 800 mL of water, then dilute to exactly 1 L and standardize by titration.
Why is normality used less often today?
Normality depends on the reaction the solution is used for, so the same solution can have different normalities. IUPAC recommends molarity instead, but normality is still common in titrations, water analysis and older laboratory methods because equivalents react one to one.
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