Enter the [H3O+] and the [OH-] into the Calculator. The calculator will evaluate the Kw Equation. 

Kw Equation Formula

Kw = [H3O+][OH-]


  • Kw is the Kw Equation ()
  • [H3O+] is the [H3O+]
  • [OH-] is the [OH-]

To calculate Kw, multiply the [H3O+] by the [OH-].

How to Calculate Kw Equation?

The following steps outline how to calculate the Kw Equation.

  1. First, determine the [H3O+]. 
  2. Next, determine the [OH-]. 
  3. Next, gather the formula from above = Kw = [H3O+][OH-].
  4. Finally, calculate the Kw Equation.
  5. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

[H3O+] = 1.003×10−7

[OH-] = 1.003×10−7