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pH and pOH calculator

Fill in what you know and leave the unknown box empty — it works out whichever one is missing. Nothing is uploaded; the arithmetic happens in your browser.

pH = 4

The formula

pH = −log₁₀[H⁺] · pH + pOH = 14

Where this usually goes wrong

The 14 holds at 25 °C. Concentrations are in mol/L.

Worked example

1 × 10⁻⁴ mol/L is pH 4.

Those numbers are already in the boxes above — press Work it out to see it, then change them for your own.

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