pH Calculator
Enter a pH, pOH, hydrogen ion concentration or hydroxide ion concentration and this calculator returns the other three values at 25 degrees Celsius, along with whether the solution is acidic, neutral or basic.
How to calculate pH
- Choose which value you know: pH, pOH, [H+] or [OH-].
- Enter that single value, using mol/L for concentrations.
- Read the other three values and the acidic, neutral or basic label.
Examples
From [H+]
[H+] = 1e-3 mol/L
pH 3, pOH 11, [OH-] = 1e-11
Neutral water
pH = 7
pOH 7, [H+] = [OH-] = 1e-7
Frequently asked questions
What is pH?
pH measures how acidic or basic a solution is. It equals the negative base-10 logarithm of the hydrogen ion concentration, pH = -log10[H+].
How are pH and pOH related?
At 25 degrees Celsius pH plus pOH equals 14, because the ion product of water [H+][OH-] is 1.0 x 10^-14.
What pH counts as acidic or basic?
At 25C a pH below 7 is acidic, exactly 7 is neutral, and above 7 is basic. The further from 7, the stronger the acid or base.
How do I get [H+] from pH?
Raise 10 to the power of negative pH: [H+] = 10^(-pH) in mol/L. This tool does the conversion in both directions.
Does temperature affect the result?
Yes. These relations assume 25 degrees Celsius. At other temperatures the value of Kw, and so neutral pH, shifts slightly.
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