Titration Endpoint Calculator

Reviewed by the CalculatorHub team, edited by James Graham. Neutralisation formula: n1C1V1 = n2C2V2. Last verified 14 June 2026.

Acid-base titration is a quantitative analytical technique used to determine the concentration of an unknown acid or base solution by reacting it with a standardised titrant until the reaction is complete (equivalence point). This calculator uses the neutralisation equation C1V1/n1 = C2V2/n2, where C is molar concentration, V is volume, and n is the stoichiometric ratio of the reaction. Enter three known values and the calculator solves for the fourth. Also calculates moles of analyte reacted.

Titrant concentration C1 (mol/L) Known concentration of your titrant (e.g., NaOH)

Titrant volume used V1 (mL) Volume of titrant from the burette at endpoint

Stoichiometric ratio n1 (titrant) e.g., 2 for H2SO4 (diprotic acid), 1 for HCl

Analyte volume V2 (mL) Volume of the unknown analyte solution in the flask

Stoichiometric ratio n2 (analyte) e.g., 2 for Ca(OH)2, 1 for NaOH

Unknown concentration C2 (mol/L)

0.00

Moles of analyte

0.00

Titration formula

C1 * V1 / n1 = C2 * V2 / n2

C2 = (C1 * V1 * n2) / (n1 * V2)

Where C1 is the titrant (known) concentration in mol/L, V1 is the volume of titrant used in mL, n1 is the number of reactive protons or hydroxyl groups per molecule of titrant, C2 is the analyte concentration, V2 is the analyte volume, and n2 is the stoichiometric factor for the analyte.

Common titration stoichiometries

HCl + NaOH: n1 = 1, n2 = 1 (1:1 ratio)
H2SO4 + NaOH: n1 = 2 for H2SO4, n2 = 1 for NaOH
H3PO4 + NaOH (complete neutralisation): n1 = 3, n2 = 1
CH3COOH + NaOH: n1 = 1, n2 = 1 (1:1 ratio)
Ca(OH)2 + HCl: n1 = 1 for HCl, n2 = 2 for Ca(OH)2

Titration endpoint: frequently asked questions

What is a titration endpoint?

The titration endpoint is the point at which the titrant has neutralised exactly the amount of analyte in the sample. At the equivalence point (ideal endpoint), moles of acid equal moles of base (for a 1:1 stoichiometry). An indicator changes colour near the equivalence point to signal the endpoint.

What is the formula for acid-base titration?

For a 1:1 acid-base reaction: n1 * C1 * V1 = n2 * C2 * V2, where n is the stoichiometric ratio, C is concentration (mol/L), and V is volume (L). For a 1:1 titration this simplifies to C1V1 = C2V2.

What indicator should I use for a strong acid-strong base titration?

Phenolphthalein (pH range 8.2 to 10.0) or bromothymol blue (pH 6.0 to 7.6) are suitable. For strong acid vs strong base, the equivalence point is at pH 7.0, so any indicator with a range near neutral works. Phenolphthalein is the most commonly used.

What indicator should I use for a weak acid-strong base titration?

Use phenolphthalein (pH range 8.2 to 10.0) because the equivalence point is above pH 7 (the salt formed is basic). Methyl orange is not suitable as it changes colour in the acidic range, far from the equivalence point.

What is the difference between the endpoint and the equivalence point?

The equivalence point is the theoretically exact point of complete neutralisation. The endpoint is the experimentally observed point where the indicator changes colour. A well-chosen indicator minimises the difference between them, called the titration error.

Official sources

NIST Standard Reference Database, acid-base equilibria: NIST Chemistry WebBook.
IUPAC Compendium of Chemical Terminology (Gold Book), titration definition: IUPAC Gold Book: Titration.

Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. See our methodology.