pOH is the negative log of the hydroxide ion concentration. Like pH, lower pOH means more basic.

Why does pH + pOH = 14?

At 25 C, the ion product of water Kw = [H+][OH-] = 10^-14, so -log(Kw) = 14 = pH + pOH.

Is pOH commonly used?

Less than pH, but useful for base calculations and understanding the relationship between acids and bases.

Free pOH Calculator

Calculate pOH from hydroxide ion concentration.

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Hydroxide Ion Concentration [OH-]

pOH

2.00

pH12.00

pOH vs Hydroxide Ion Concentration [OH-]

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How to Calculate pOH

Formula

pOH = -log10([OH-])

And: pH + pOH = 14 (at 25 C)

Example Calculation

[OH-] = 0.01 M.

01pOH = -log10(0.01)
02pOH = 2
03pH = 14 - 2 = 12

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Related Calculators

pH Calculator

Calculate pH from [H+].

Hydroxide Ion Calculator

Calculate [OH-] from pOH.

Ion Product of Water Calculator

Explore the Kw relationship.