🧫Buffer pH Calculator

Use the Henderson-Hasselbalch equation to find buffer pH from pKa and conjugate acid/base concentrations.

pKa

[A⁻] Conjugate Base (M)

[HA] Weak Acid (M)

Free Buffer pH Calculator

This buffer pH calculator applies the Henderson-Hasselbalch equation, pH = pKa + log([A⁻]/[HA]), to find the pH of a buffer solution made from a weak acid and its conjugate base. Enter the acid's pKa along with the concentrations of the conjugate base and weak acid, and the calculator returns the buffer pH along with the [A⁻]/[HA] ratio.

Buffers resist pH changes best when the ratio of base to acid is close to 1:1 (pH close to pKa) — this is where buffer capacity is highest. As the ratio moves away from 1:1, the buffer becomes progressively less effective at resisting further pH changes.

Useful for biochemistry, analytical chemistry, and lab buffer preparation. Free, runs entirely in your browser.