basic

pKb from pKa Conversion Calculator

pKb = 14.00 − pKa (and pKa = 14.00 − pKb) at 25 °C.

Convert a weak acid's pKa to the corresponding pKb of its conjugate base (or vice-versa) using the relation pKa + pKb = pKw, where pKw = 14.00 at 25 °C. Reports both the pKb and the dissociation constants Ka and Kb in scientific notation.

Dr. Helena Ortiz By Dr. Helena Ortiz
Published Last reviewed 1 min read

Inputs

Results

Enter values and click Calculate to see results.
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How to use this calculator

  1. Fill in the inputs above using the units you already have.
  2. Values update automatically as you type — no submit button needed.
  3. Hover any result row for the underlying formula and intermediate values.

Formula

pKa + pKb = pKw (≈ 14.00 at 25 °C).

In depth

Convert a weak acid's pKa to the corresponding pKb of its conjugate base (or vice-versa) using the relation pKa + pKb = pKw, where pKw = 14.00 at 25 °C. Reports both the pKb and the dissociation constants Ka and Kb in scientific notation.