pH & pOH Calculator

pH is the logarithm of hydrogen-ion concentration. Slide the concentration and see the pH, pOH, and where the solution lands on the color scale.

pH & pOH CalculatorLive

acids, bases, and the pH scale

3.0

acidic

0714

Controls

pH measures hydrogen-ion concentration on a logarithmic scale. Each unit is a 10× change — pH 3 is ten times more acidic than pH 4.

Presets

Concentration 10⁻ⁿ M (n)

▶ Run in Python

Data Inspector

pH3.00

pOH11.00

[H⁺]1.0e-3

[OH⁻]1.0e-11

Governing equation

pH = - lo g_{10} [H^{+}] = - lo g_{10} (1.0 e - 3) = 3.00

Reading this result: Acidic: [H⁺] of 1.0e-3 M outnumbers OH⁻, and because pH + pOH always sums to 14, the pOH here is 11.0.

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How it works

pH = -log[H+], so every unit is a tenfold change in acidity. This calculator converts between concentration, pH, and pOH and places the result on the familiar 0-14 scale, the everyday language of chemistry, biology, and medicine.

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Frequently asked questions

Is this pH calculator tool really free?▾

Yes. pH & pOH Calculator runs entirely in your browser using your device's own compute, so local use is free forever. You only pay Compute Tokens if you scale a job to the cloud.

Do I need to install anything?▾

No. Everything runs client-side in a modern browser — no downloads, no license, no account required to start.

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Create a free account to save projects, and use a shareable embed or minted DOI to publish a live, interactive version anywhere.

How accurate are the results?▾

The solver uses established numerical methods, but results are for research and educational purposes and should be validated against experiment or professional review before you rely on them.