pH to pOH Online Calculator

When pH value is known, pOH can be calculated. Also, when pOH is known, pH can be calculated. This calculation values depend on the temperature. Different temperatures are given in this online pH to pOH calculator.

There are only two simple steps in this pH to pOH calculaor and they are mentioned below.

  1. Select the temperature (Neutralized pH at standard temperature 250C is 7)
  2. Enter pH value and calculate it.




pOH value




How to calculate pOH from pH

Summation of pH and pOH values is a constant in a specified temperature. As an example, at 250C, pH + pOH = 14 .

This constant can be calculated from the dissociation constant of water (Kw) which depends on the temperature.

pH + pOH = constant

constant = -log10(Kw)


Example: Calculate pOH value, when aqueous solution's pH value is 5. temperature is 250C.

  • pH + pOH = 14
  • 5 + pOH = 14
  • pOH = 9