Titration Calculator
Work out the unknown concentration from a titration, or how much titrant you will need to reach the equivalence point. Any mole ratio is supported, and for acid–base titrations you also get the pH at equivalence, a titration curve and a suitable indicator.
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Coefficients from the balanced equation
e.g. H2SO4 + 2NaOH: analyte 1, titrant 2
How to use the Titration Calculator
- Choose what to calculate: the analyte concentration or the titrant volume.
- Enter the titrant concentration and the endpoint volume from the burette.
- Enter the analyte volume pipetted into the flask.
- Set the mole ratio from the balanced equation (1 : 1 for HCl + NaOH).
- Pick the analyte type to see the pH curve, equivalence pH and indicator.
Titration formulas
| Quantity | Formula |
|---|---|
| Moles of titrant | nt = Ct × Vt |
| Moles of analyte | na = nt × (a ÷ b) |
| Analyte concentration | Ca = na ÷ Va = CtVta ÷ (bVa) |
| Equivalence volume | Veq = CaVab ÷ (aCt) |
| Half-equivalence (weak acid) | pH = pKa |
a and b are the coefficients of the analyte and titrant in the balanced equation. Volumes must be in liters when concentrations are in mol/L; the calculator takes mL and converts for you.
Acid–base indicators
| Indicator | pH range | Color change (acid → base) | Good for |
|---|---|---|---|
| Methyl orange | 3.1 – 4.4 | red → yellow | Strong acid with weak base |
| Bromocresol green | 3.8 – 5.4 | yellow → blue | Weak base with strong acid |
| Methyl red | 4.4 – 6.2 | red → yellow | Weak base with strong acid |
| Bromothymol blue | 6.0 – 7.6 | yellow → blue | Strong acid with strong base |
| Phenol red | 6.8 – 8.4 | yellow → red | Strong acid with strong base |
| Phenolphthalein | 8.2 – 10.0 | colorless → pink | Weak acid with strong base |
| Thymolphthalein | 9.3 – 10.5 | colorless → blue | Very weak acids |
The titration curve is computed from the full charge balance with Kw = 1.0 × 10⁻¹⁴ (25 °C) and ignores activity effects, so it matches textbook curves for dilute solutions. Polyprotic weak acids (such as phosphoric acid) show several steps and are not modelled; the concentration result is still valid for them.
Frequently asked questions
How do I calculate concentration from a titration?
Moles of titrant = concentration × volume (in liters). Convert to moles of analyte with the mole ratio from the balanced equation, then divide by the analyte volume in liters. For 24.6 mL of 0.100 M NaOH neutralizing 25.0 mL of acetic acid (1:1): 0.00246 mol ÷ 0.0250 L = 0.0984 M.
What is the equivalence point?
It is the point where the titrant added exactly reacts with all the analyte according to the balanced equation. The endpoint is where the indicator changes color; a good indicator makes the endpoint very close to the equivalence point.
Why do I need the mole ratio?
Some reactions do not react 1:1. Sulfuric acid releases two protons, so H₂SO₄ + 2NaOH → Na₂SO₄ + 2H₂O needs 2 mol NaOH per mol acid. Ignoring that doubles the calculated acid concentration.
Can I use M₁V₁ = M₂V₂ for titrations?
Only when the ratio is 1:1. The general form is (C₁V₁) ÷ a = (C₂V₂) ÷ b, where a and b are the coefficients of the analyte and titrant.
Why is the equivalence pH not 7 for a weak acid?
At equivalence the solution contains the conjugate base of the weak acid (for example acetate), which reacts with water to make OH⁻, so the pH is above 7, about 8.7 for 0.1 M acetic acid. A weak base titrated with a strong acid gives an equivalence pH below 7.
Which indicator should I use?
Choose one whose color-change range includes the equivalence pH: phenolphthalein (8.2–10.0) for weak acid–strong base, methyl orange or methyl red for weak base–strong acid, and almost any of them for strong acid–strong base because the pH jump is so steep.
What is the pH at half-equivalence?
For a weak acid titrated with a strong base, half the acid has been converted to its conjugate base, so [HA] = [A⁻] and pH = pKa by the Henderson-Hasselbalch equation. It is a common way to measure pKa.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.