pH Calculator

How to calculate pH

1. Choose what you know: pH, [H⁺], pOH, [OH⁻], or the concentration of a strong or weak acid or base.
2. Type the value, and for a weak acid or base, its pKa or pKb.
3. The pH, pOH, [H⁺] and [OH⁻] appear, along with whether the solution is acidic, neutral or basic.

Frequently asked questions

At what temperature is this?

25 °C, where pH + pOH = 14.

How is a weak acid handled?

The equilibrium is solved exactly with the quadratic formula rather than with the usual approximation, so it also works for dilute or fairly strong weak acids.