pH Calculator
pH, pOH and ion concentrations.
Enter your values
ⓘ Live results
Results
- pH
- 3.5
- pOH
- 10.5
- [H⁺]
- 3.1623e-4 mol/L
- [OH⁻]
- 3.1623e-11 mol/L
- Classification
- Acidic
Working
- 1pH = −log₁₀(3.162e-4) = 3.5
Quick answer
pH = −log₁₀[H⁺], and pH + pOH = 14 at 25°C.
pH = −log₁₀[H⁺]
How to use the pH Calculator
- 1Enter the value you know.
- 2Select which quantity it is.
- 3Read pH, pOH and both ion concentrations.
Worked example
Using the values the calculator loads with:
Inputs
- Value3.5
- GivenpH
Results
- pH3.5
- pOH10.5
- [H⁺]3.1623e-4 mol/L
- [OH⁻]3.1623e-11 mol/L
- ClassificationAcidic
- pH = −log₁₀(3.162e-4) = 3.5
Frequently asked questions
Why is pH 7 neutral?
At 25°C water self-ionises so [H⁺] = [OH⁻] = 10⁻⁷ mol/L. At other temperatures neutral pH shifts slightly.
Can pH be negative?
Yes. Concentrated strong acids above 1 M give negative pH values.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.