Buffer pH Calculator (Henderson-Hasselbalch)
Reviewed by Hamza Gujjar, Algorithm Architect & Software Developer
Last updated: July 27, 2026Why buffers resist pH change
The Henderson-Hasselbalch equation calculates buffer pH from the ratio of conjugate base to weak acid concentration - this mathematical relationship is exactly why buffers resist pH swings, since adding acid or base shifts this ratio only gradually.
Worked example
For a buffer with pKa 4.76 and equal concentrations of conjugate base and acid (0.1M each):
pH = 4.76 + log10(0.1/0.1) = pH = 4.76
When conjugate base and acid concentrations are exactly equal, the log term becomes log10(1) = 0, meaning pH exactly equals pKa - this is precisely the point of maximum buffering capacity, where the solution most effectively resists pH change in either direction.