Buffer pH Calculator

Summary

Select a common buffer or enter your own pKa and acid/base concentrations to calculate buffer pH and effective buffering range.

How it works

1. Select a preset buffer from the dropdown (e.g., Acetate, Phosphate, Tris) or choose "Custom" and enter your own pKa.
2. Enter the concentration of the weak acid [HA] and the conjugate base [A⁻] in mol/L (molar).
3. The buffer pH is calculated instantly using pH = pKa + log([A⁻]/[HA]).
4. The tool displays the base-to-acid ratio, buffer capacity estimate, and effective buffering range (pKa ± 1).
5. A visual scale shows where your calculated pH falls relative to the effective range.
6. Use the Copy button to save the full result summary to your clipboard.

Use cases

• Prepare acetate or phosphate buffers for biochemistry lab experiments.
• Design cell culture media buffers (HEPES, MES, PIPES) at a precise pH.
• Verify buffer pH from measured component concentrations.
• Quickly look up pKa values for 15 common buffer systems.
• Estimate buffer capacity before mixing large-volume solutions.
• Check whether a chosen buffer system is appropriate for a target pH.
• Prepare for chemistry exams by practicing Henderson-Hasselbalch calculations.
• Cross-check manual buffer calculations against a reliable reference.

Frequently Asked Questions