Enter the total pH value into the pOH Calculator. The calculator will evaluate the pOH. This calculator can also determine the pH given the pOH.

pH ↔ pOH Calculator

pH ↔ pOH
pH from [H+]
pOH from [OH−]
Strong acid/base
Weak acid/base
Buffer (H–H)
Mix SA+SB

pOH Formula

The following two example problems outline the steps and information needed to calculate the pOH.

pOH = 14 - pH
pH = 14 - pOH
  • pOH is the pOH
  • pH is the total pH value 

To calculate pOH, simply subtract the pH value from 14.

pH to pOH Conversion Table (25°C, pKw = 14.00)
pH pOH
0.0014.00
1.0013.00
2.0012.00
3.0011.00
4.0010.00
5.009.00
5.508.50
6.008.00
6.507.50
7.007.00
7.206.80
7.406.60
8.006.00
8.505.50
9.005.00
10.004.00
11.003.00
12.002.00
13.001.00
14.000.00
At 25°C, pKw ≈ 14.00, so pH + pOH = 14.00. Values rounded to 2 decimals.

How to Calculate pOH?

The following steps outline how to calculate the pOH.


  1. First, determine the total pH value. 
  2. Next, gather the formula from above = pOH = 14 - pH.
  3. Finally, calculate the pOH.
  4. 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.

the total pH value = 8

pOH = 14 - pH = ?