pH Calculator
Convert between hydrogen ion concentration and pH.
Concentration in mol/L, or a pH value.
Acidity in both directions
The pH scale compresses an enormous range of hydrogen ion concentrations into a simple 0-to-14 number using a logarithm. This calculator moves between the two representations freely.
A hydrogen ion concentration of 0.0001 mol/L is a pH of 4 — acidic. Switch modes and enter a pH to recover the concentration, and see the matching pOH and hydroxide concentration.
Two-way and private
It applies the pH logarithm in your browser, so nothing you enter is uploaded.
Frequently Asked Questions
What is pH?
The negative base-10 logarithm of the hydrogen ion concentration. Lower pH is more acidic, higher is more basic, with 7 neutral.
Can it work both ways?
Yes. Enter a concentration to get pH, or a pH to get the concentration.
What is pOH?
The hydroxide-ion equivalent. At 25°C, pH plus pOH equals 14.
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