Henderson–Hasselbalch Calculator

About this calculator

This calculator finds a buffer's pH using the Henderson–Hasselbalch equation: pH = pKa + log₁₀([A⁻]/[HA]), where pKa is the acid dissociation constant of the weak acid, [A⁻] is the concentration of its conjugate base, and [HA] is the concentration of the undissociated acid. It's derived directly from the acid dissociation equilibrium constant Ka.

Chemists use it to prepare buffer solutions at a target pH for lab work and titrations, and it's foundational in biochemistry and physiology for understanding blood buffering systems like the bicarbonate buffer, which keeps arterial blood pH tightly regulated near 7.4. Enter the pKa and the concentrations of the conjugate base and acid to calculate the resulting pH.