What is a pH & pOH Calculator?

It is a chemistry tool that tells you the acidity or basicity of a solution. pH and pOH are both measures of hydrogen ion (H⁺) and hydroxide ion (OH⁻) concentration in an aqueous solution.

What is pH?

pH is a number scale (from 0 to 14) that indicates the acidity or alkalinity of a solution.

• If pH < 7, the solution is acidic.
• If pH = 7, the solution is neutral.
• If pH > 7, the solution is basic (alkaline).

Formula:

pH = −log [H⁺]

Example:
If [H⁺] = 1 × 10⁻³ M,
then pH = 3

What is pOH?

pOH is a similar scale that indicates hydroxide ion (OH⁻) concentration.

• If pOH < 7, the solution is basic.
• If pOH > 7, the solution is acidic.

Formula:
pOH = −log [OH⁻]

Relationship between pH and pOH

There is a simple relationship between the two:
pH + pOH = 14 (at 25°C)

With this formula, if you have the pH value, you can find the pOH, and if you have the pOH, you can easily calculate the pH.

How to use the calculator

• Enter the H⁺ or OH⁻ ion concentration.
• Press the "Calculate" button.
• You will get the pH, pOH, and nature of the solution (acidic/basic/neutral).

Example

Input: [H⁺] = 1 × 10⁻⁵
Output:

• pH = 5
• pOH = 9
• Solution = Acidic