Laboratory & Chemistry

pH Calculator

Calculate pH from hydrogen-ion or hydroxide-ion concentration at 25 °C.

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Calculator

Result

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Enter valid values and calculate.
Formula: From [H⁺]: pH = −log₁₀[H⁺]. From [OH⁻]: pH = 14 − pOH, where pOH = −log₁₀[OH⁻].

About this calculator

Calculate pH from hydrogen-ion or hydroxide-ion concentration at 25 °C.

Enter valid values, then select Calculate. The calculation runs in your browser and does not require an account.

Formula / reference: From [H⁺]: pH = −log₁₀[H⁺]. From [OH⁻]: pH = 14 − pOH, where pOH = −log₁₀[OH⁻].

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How to use this calculator

What to enter

Enter or select the following as requested: Concentration. Follow the units, valid ranges, examples, and options displayed beside each field.

What the result means

The scientific or engineering result follows the formula and units used by the calculator with the values entered. Check unit consistency, significant figures, assumptions, and whether the model applies to the material or conditions being studied.

When to use it

Use this for calculation checks, study, or preliminary engineering estimates. Validate critical laboratory, process, or safety decisions with the appropriate method, standards, and qualified review.