pH Calculator

Use pH = -log10[H+] or pOH = -log10[OH-] and see the corresponding pH, pOH, H+, and OH- values at 25 °C.

Calculate from

Value

—Uses pH + pOH = 14 at 25 °C and Kw = 1.0×10⁻¹⁴. This is a direct concentration relationship, not an equilibrium solver.

—pH

—pOH

—[H+] mol/L

—[OH−] mol/L

How to use this pH Calculator

Calculate pH or pOH directly from hydrogen or hydroxide ion concentration. Enter your values above and the result is calculated directly in your browser. No account is required.

Fast answer, clear inputs

This tool is built around one job: give the answer quickly without forcing a signup or hiding the result. Related tools are linked nearby when the next calculation or conversion is useful.