pH / pOH Converter

How it is calculated

You give one known quantity and say which kind it is: pH, pOH, [H⁺] or [OH⁻]. The tool turns it into pH first. From a concentration: pH = −log₁₀[H⁺], or pH = 14 + log₁₀[OH⁻]. From pOH: pH = 14 − pOH. Then it gives all four values: pOH = 14 − pH, [H⁺] = 10⁻ᵖᴴ and [OH⁻] = 10⁻ᵖᴼᴴ. Concentrations are in mol/L and must be above zero when they are the input; pH and pOH inputs may be any number, so values below 0 or above 14 are accepted without a warning. The 14 is valid at 25 °C, which is the only temperature the tool uses. pH and pOH are rounded to two decimals, and concentrations are written in scientific notation with two decimals, always with a decimal point, even in Turkish.

Common mistakes

• Leaving the input type on pH while typing a concentration. A value such as 0.0002 would then be read as a pH of 0.0002, not as a concentration.
• Choosing [H⁺] when the number you have is [OH⁻]. This gives a pH that is mirrored around 7 (3.70 instead of 10.30).
• Entering the concentration in mmol/L or in percent. The tool expects mol/L.
• Entering a pOH when you meant pH. The two add up to 14, so mixing them reverses acidic and basic.
• Trusting a result outside the 0–14 range or at a temperature far from 25 °C. The tool accepts such values but the relationship between the two scales shifts with temperature.