pH calculator

pH, pOH, [H⁺], and [OH⁻] — enter any one and get the other three at 25 °C.

pH + pOH = 14 at 25 °C. Solve from whichever one quantity you know.

Concentrations up to 10 mol/L are allowed, so strong acids/bases can show pH below 0 or above 14.

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How to use

  1. Enter pH, pOH, [H⁺], or [OH⁻].
  2. Calculate.
  3. Read all four values.

What it supports

Aqueous solutions at 25 °C (Kw = 1e-14). pH −1…15 displayable; concentrations 1e-15…10 mol/L. Strong-acid/base assumptions — no activity coefficients or weak equilibria.

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