Buffer Calculator
How to calculate a buffer
- Choose a buffer from the list, or Other and type its pKa.
- Type the target pH, the total buffer concentration and the volume.
- The ratio of base to acid and the amount of each appear, with a warning if the pH is outside the buffering range.
Frequently asked questions
What is the Henderson-Hasselbalch equation?
pH = pKa + log([A⁻]/[HA]). It gives the ratio of conjugate base to acid needed for a pH.
Why keep within pKa ± 1?
A buffer resists pH changes best close to its pKa. Beyond one unit either side there is too little acid or base left to absorb much.