pH Calculator
Calculate pH from hydrogen ion concentration. Free online pH and pOH calculator.
The pH Calculator determines pH from hydrogen ion concentration [H⁺] and vice versa. Calculate pH, pOH, and ion concentrations for acids and bases. This tool is essential for chemistry labs, environmental science, pool maintenance, and any application requiring acidity/alkalinity measurements.
Common use cases
- Laboratory acid-base chemistry
- Pool and spa maintenance
- Environmental water testing
- Soil acidity analysis
- Food science applications
How to use
- Enter [H⁺] concentration OR pH value
- Click calculate for all related values
- View pH, pOH, [H⁺], and [OH⁻]
- Understand acid/base character
- See the calculation formulas
FAQ
What is pH?
pH = -log₁₀[H⁺], measuring acidity. pH < 7 is acidic, pH = 7 is neutral, pH > 7 is basic.
What is the pH scale range?
Typically 0-14 for aqueous solutions, though extreme acids/bases can go beyond.
How are pH and pOH related?
pH + pOH = 14 at 25°C. Also, [H⁺] × [OH⁻] = 10⁻¹⁴ (Kw).
What does pH tell us?
Each pH unit represents a 10-fold change in [H⁺]. pH 4 is 10× more acidic than pH 5.