Convert between pH, pOH and ion concentrations — enter a hydrogen-ion concentration or a pH and get the full picture, at 25 °C.
pH Calculator
pH
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pOH
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Hydrogen ion concentration [H⁺]
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Hydroxide concentration [OH⁻]
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How it works: pH = −log₁₀[H⁺], so every pH step is a tenfold change in acidity: pH 3 is ten times more acidic than pH 4. At 25 °C, pH + pOH = 14, [H⁺] = 10^(−pH) and [OH⁻] = 10^(−pOH). Below 7 is acidic, 7 is neutral (pure water), above 7 is basic. Lemon juice sits near pH 2, blood near 7.4, and household bleach near 13.
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Estimates only — results depend on the values you enter and the standard formulas shown above.