Buffer pH (Henderson-Hasselbalch) Calculator
Enter the pKa and the base and acid concentrations to find the buffer pH.
Result
How to use
- Enter your values in the fields above.
- Press Calculate to see your result instantly.
- Use the Share button to copy a link to your result.
About this calculator
The Henderson-Hasselbalch equation, pH = pKa + log([A⁻]/[HA]), relates the pH of a buffer solution to the acid dissociation constant (pKa) of a weak acid and the ratio of its conjugate base concentration [A⁻] to its own concentration [HA]. When the two concentrations are equal, the log term vanishes and pH equals pKa exactly.
Because it links a measurable ratio of concentrations to pH without needing to solve the full equilibrium expression, this equation is the standard shortcut chemists and biochemists use to design and analyze buffer solutions — mixtures that resist pH change when small amounts of acid or base are added.
Buffers built this way are essential in biochemistry (maintaining physiological pH near 7.4 in blood, using the bicarbonate system), pharmaceutical formulation, and laboratory reagent preparation, where a stable pH is required for reactions or assays to behave predictably.
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