Science
pH calculator
Concentration [H⁺] → pH, pOH and [OH⁻] of a solution.
- Instant
- Free
- Private (processed locally)
- No sign-up
Calculate a solution’s pH
Enter the H⁺ ion concentration (mol/L). The tool applies pH = −log₁₀[H⁺] and derives pOH and [OH⁻].
Reference points
- pH 0–6: acidic
- pH 7: neutral (pure water)
- pH 8–14: basic
- pH + pOH = 14 (at 25 °C)
Examples
| [H⁺] (mol/L) | pH |
|---|---|
| 10⁻¹ | 1 (strong acid) |
| 10⁻³ | 3 |
| 10⁻⁷ | 7 (neutral) |
| 10⁻¹¹ | 11 (basic) |
Calculation at 25 °C. 100% local, no data sent.
Frequently asked questions
How is pH calculated?
pH = −log₁₀[H⁺], where [H⁺] is the concentration in mol/L. E.g. [H⁺] = 10⁻³ → pH = 3.
And pOH?
At 25 °C, pH + pOH = 14, so pOH = 14 − pH, and [OH⁻] = 10⁻ᵖᴼᴴ.
What scale for acidic/basic?
pH < 7 acidic, pH = 7 neutral, pH > 7 basic (at 25 °C).
How do I enter the concentration?
In scientific notation: 1e-3 for 10⁻³, 5e-9, etc.