Henderson-Hasselbalch Calculator

What Is a Buffer pH (Henderson-Hasselbalch) Calculator?

A buffer solution resists changes in pH by containing both a weak acid and its conjugate base. The Henderson-Hasselbalch equation lets you calculate the buffer's pH directly from the acid's pKa and the ratio of base to acid present.

How to Use This Buffer pH (Henderson-Hasselbalch) Calculator

1. Enter the pKa of the weak acid used in the buffer.
2. Enter the concentration of the conjugate base [A-].
3. Enter the concentration of the weak acid [HA].
4. Click Calculate to get the buffer's pH.

Formula

• pH = pKa + log₁₀([A-] / [HA])

Worked Example

A buffer uses acetic acid (pKa = 4.76) with [A-] = 0.2 M and [HA] = 0.1 M. pH = 4.76 + log₁₀(0.2/0.1) = 4.76 + 0.301 ≈ 5.06.