basic

Buffer A⁻/HA Ratio from Target pH Calculator

Solve [A⁻]/[HA] from a target pH and the acid pKa.

Inverse Henderson-Hasselbalch: given a target buffer pH and the acid pKa, compute the required [A⁻]/[HA] ratio (and the % of total buffer that should be in the conjugate-base form).

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

Inputs

Results

Enter values and click Calculate to see results.
Was this helpful?

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

[A⁻]/[HA] = 10^(pH − pKa)

In depth

Inverse Henderson-Hasselbalch: given a target buffer pH and the acid pKa, compute the required [A⁻]/[HA] ratio (and the % of total buffer that should be in the conjugate-base form).