M To Normality Calculator

Convert between molarity and normality, or do the lab work directly: weigh out solute for a target normality, or find the normality of what you weighed. Pick a compound (acids, bases, redox reagents, and salts with correct n-factors and molar masses) or enter a custom n-factor, then choose one of the four modes.

Worked examples, checked against this exact tool

M → N: 0.25 M H2SO4 (n = 2) gives 0.500 N. N → M: 0.5 N H2SO4 converts back to 0.25 M. Grams to prepare: 250 mL of 0.1 N HCl (molar mass 36.46, n = 1) needs 0.9115 g. N from mass: 0.79 g of KMnO4 (n = 5, acidic) in 500 mL gives 0.0500 N.

What the n-factor really is

The n-factor (equivalence factor) is the number of reactive units one molecule provides in a specific reaction: replaceable H+ for acids, OH− for bases, electrons transferred for redox, total charge for salts. Normality counts these reactive units per liter; molarity counts molecules per liter. That is the whole relationship: N = M × n. For monoprotic HCl, n = 1 and the two are numerically equal; for H2SO4 in acid-base work, n = 2 and normality is double the molarity.

The n-factor depends on the reaction

This is the subtlety most tables gloss over. The same bottle of H2SO4 is 2 N per mole in acid-base neutralization (two H+ donated) but 1 N per mole in a sulfate-precipitation reaction (one sulfate ion). H3PO4 can be n = 1, 2, or 3 depending on how many of its protons actually react; the preset uses 3 for full neutralization. KMnO4 is n = 5 in acidic medium (Mn7+ → Mn2+, five electrons) but n = 3 in alkaline medium. When in doubt, write the balanced half-reaction and count.

The four modes

• M → N: N = M × n. The classic conversion for titration math.
• N → M: M = N ÷ n. For when a procedure specifies normality and you need molarity.
• Grams to prepare: mass = N × V(L) × molar mass ÷ n. Weigh this much solute, dissolve, and make up to the final volume in a volumetric flask.
• N from mass: N = (mass ÷ molar mass × n) ÷ V(L). For checking what you actually made.

The tool also shows the equivalent weight (molar mass ÷ n): the grams of solute per equivalent. For H2SO4 that is 98.08 ÷ 2 = 49.04 g/eq; for KMnO4 in acid it is 158.03 ÷ 5 = 31.61 g/eq.

Normality in titrations: N1V1 = N2V2

Normality earns its keep at the equivalence point: one equivalent of acid neutralizes exactly one equivalent of base, so N1 × V1 = N2 × V2 regardless of the molecules involved. A 0.1100 N base titrating an acid sample needs no molecular bookkeeping: equivalents in equals equivalents out. This is why analytical labs still use normality even though IUPAC recommends molarity as the unambiguous, reaction-independent unit.

What competing calculators miss

The strongest rival tools cover the same four modes with redox presets and equivalent weights, but bury them in dense textbook pages. Others do M → N only, or equivalent weight only. One popular worked example even prints an arithmetic error for its Na2CO3 case. This page combines all four modes with acid, base, redox, and salt presets, shows equivalent weight on every result, and carries the reaction-specificity warning that the n-factor tables need.

Frequently asked questions

What is the difference between normality and molarity?

Molarity counts moles of solute per liter; normality counts reactive equivalents per liter. They are linked by N = M × n, where n is the n-factor.

How do you convert molarity to normality?

Multiply by the n-factor: 0.25 M H2SO4 (n = 2) = 0.50 N. Use the M → N mode above.

How do you convert normality to molarity?

Divide by the n-factor: 0.5 N H2SO4 (n = 2) = 0.25 M. Use the N → M mode above.

What is the n-factor?

The number of reactive units per molecule in a given reaction: H+ for acids, OH− for bases, electrons for redox, charge for salts.

How many grams do I need for a 0.1 N solution?

Mass = N × volume(L) × molar mass ÷ n. For 250 mL of 0.1 N HCl: 0.1 × 0.25 × 36.46 ÷ 1 = 0.9115 g.

What is equivalent weight?

Molar mass divided by the n-factor: the grams per equivalent. H2SO4: 98.08 ÷ 2 = 49.04 g/eq.

Why is the n-factor of H2SO4 sometimes 1 and sometimes 2?

It depends on the reaction: 2 for full acid-base neutralization (two H+ donated), 1 for sulfate precipitation (one sulfate ion). Always check the balanced equation.

What is the n-factor of KMnO4?

5 in acidic medium (Mn7+ gains 5 electrons to become Mn2+), 3 in alkaline medium. The preset uses the acidic value.

What is N1V1 = N2V2?

The titration equivalence equation: normality × volume of titrant equals normality × volume of analyte at the equivalence point.

Why does IUPAC discourage normality?

Because it is reaction-dependent: the same solution can be 1 N, 2 N, or 3 N in different reactions, which causes errors when the context is not stated. Molarity is unambiguous.