Buffer Solution Calculator
Calculate buffer pH using Henderson-Hasselbalch equation. Design buffer solutions.
pH Scale & Buffer Range
Results
4.76
pH
4.76
pKa
0.1
[HA] (M)
0.1
[A-] (M)
[A-]/[HA] Ratio
1.000
Buffer Capacity
Excellent
Effective Buffer Range
pH 3.76 - 5.76
Common Buffer Systems
SystempKapH Range
Acetic acid/Acetate4.763.8 - 5.8
Phosphate (H2PO4-/HPO4 2-)7.216.2 - 8.2
Tris buffer8.077.1 - 9.1
Carbonic acid/Bicarbonate6.355.3 - 7.3
Ammonia/Ammonium9.258.3 - 10.3
HEPES7.556.5 - 8.6
Citric acid (pKa2)4.763.8 - 5.8

Henderson-Hasselbalch Equation

pH = pKa + log([A-]/[HA])
pKa = -log(Ka)
Buffer range: pKa ± 1

Buffer Capacity Notes:

  • Excellent: ratio between 0.5 and 2
  • Good: ratio between 0.1 and 10
  • Poor: ratio outside these ranges
  • Best buffering when [HA] = [A-] (pH = pKa)

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