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pH calculator

Calculate pH from hydrogen-ion concentration, convert pOH, or estimate buffer pH with Henderson–Hasselbalch.

Calculator
FormulapH ≈ −log₁₀[H⁺] · pH + pOH ≈ 14 at 25 °C · Buffer: pH ≈ pKₐ + log₁₀([A⁻]/[HA])

Use [H⁺], not total acid concentration.

mol/L

Assumes an aqueous solution at 25 °C.

Use the pKa at the relevant temperature.

Both buffer components must be present.

mol/L

Use the same concentration basis as the acid.

mol/L
Estimated pH —