pH Calculator

pH Calculator

This online calculator allows you to calculate pH or pOH of a solution based on the concentration of H⁺ or OH⁻ ions. You'll get not only the numerical value but also the solution type: acidic, neutral, or basic.

What is pH?

pH is a measure of the acidity of an aqueous solution, defined as the negative decimal logarithm of hydrogen ion concentration:

pH = -log₁₀[H⁺]

The pH scale ranges from 0 (very acidic) to 14 (very basic). A solution with pH = 7 is considered neutral (e.g., pure water).

What if you only have OH⁻?

You can enter only the hydroxide ion concentration [OH⁻]. The calculator will first compute pOH:

pOH = -log₁₀[OH⁻]

Then use the relationship:

pH + pOH = 14

Why is this useful?

• Chemical analysis of water, solutions, acids, and bases acidity
• Laboratory calculations in school, college, university
• Working with biological or medical samples
• Agriculture and hydroponics - checking soil or water pH

Examples:

• [H⁺] = 1 × 10⁻³ mol/L → pH = 3 → acidic solution
• [OH⁻] = 1 × 10⁻⁴ mol/L → pOH = 4 → pH = 10 → basic solution
• [H⁺] = 1 × 10⁻⁷ mol/L → pH = 7 → neutral solution