pH Calculator
pH from [H⁺] concentration, pOH, pKa/pKb
Enter any one value — others compute automatically
📚 Learn more — how it works, FAQ & guide Click to expand
Learn more — how it works, FAQ & guide
Click to expand
pH calculator
Calculate pH, pOH, [H⁺], [OH⁻] from any one value. At 25°C.
How to use this tool
- 1
Enter any one value
pH, pOH, [H⁺], or [OH⁻].
- 2
See all others
Computed automatically at 25°C.
- 3
Classify solution
Acidic, neutral, or basic.
Frequently Asked Questions
pH + pOH = 14?
Yes, at 25°C. pH = -log₁₀[H⁺]. pOH = -log₁₀[OH⁻]. Water equilibrium: [H⁺][OH⁻] = 10⁻¹⁴.
pH scale
0-6 acidic, 7 neutral, 8-14 basic. Each unit = 10× concentration change. pH 3 has 10× more H⁺ than pH 4.
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