A free online tool for buffer pH calculations. Approximate pH values are calculated with Henderson-Hasselbalch equation. It also provides a list of pKa values of buffers commonly used in biology and biochemistry.
Fill all but one field and click 'Calculate':
| pH | = | pKa | + | log |
[A-]
[HA]
|
| [A-] | - | concentration of the conjugate base |
| [HA] | - | concentration of the conjugate acid |
| Buffer | Useful pH Range | pKa (at 25°C) |
| Phosphate | 1.7 - 2.9, 5.8 - 8.0 | 2.15, 7.20, 12.33 |
| Glycine | 2.2 - 3.6, 8.8 - 10.6 | 2.35, 9.78 |
| Citrate | 3.0 - 6.2 | 3.13, 4.76, 6.40 |
| Acetate | 3.7 - 5.6 | 4.76 |
| MES | 5.5 - 6.7 | 6.10 |
| Bis-Tris | 5.8 - 7.2 | 6.50 |
| Carbonate | 6.0 - 8.0, 9.5 - 11.1 | 6.35, 10.33 |
| ADA | 6.0 - 7.2 | 6.59 |
| ACES | 6.1 - 7.5 | 6.78 |
| PIPES | 6.1 - 7.5 | 6.76 |
| MOPSO | 6.2 - 7.6 | 6.90 |
| Imidazole | 6.2 - 7.8 | 6.95 |
| Bis-Tris Propane | 6.3 - 9.5 | 6.8, 9.0 |
| BES | 6.4 - 7.8 | 7.09 |
| MOPS | 6.5 - 7.9 | 7.20 |
| TES | 6.8 - 8.2 | 7.40 |
| HEPES | 6.8 - 8.2 | 7.48 |
| DIPSO | 7.0 - 8.2 | 7.60 |
| MOBS | 6.9 - 8.3 | 7.60 |
| TAPSO | 7.0 - 8.2 | 7.60 |
| Tris | 7.0 - 9.0 | 8.06 |
| HEPPSO | 7.1 - 8.5 | 7.80 |
| POPSO | 7.2 - 8.5 | 7.80 |
| TEA | 7.3 - 8.3 | 7.80 |
| EPPS | 7.3 - 8.7 | 8.00 |
| Tricine | 7.4 - 8.8 | 8.05 |
| Gly-Gly | 7.5 - 8.9 | 8.20 |
| Bicine | 7.6 - 9.0 | 8.26 |
| HEPBS | 7.6 - 9.0 | 8.30 |
| TAPS | 7.7 - 9.1 | 8.40 |
| AMPD | 7.8 - 9.7 | 8.80 |
| TABS | 8.2 - 9.6 | 8.90 |
| AMPSO | 8.3 - 9.7 | 9.00 |
| Boric acid | 8.5 - 10.2 | 9.23, 12.74, 13.80 |
| CHES | 8.6 - 10.0 | 9.49 |
| CAPSO | 8.9 - 10.3 | 9.60 |
| AMP | 9.0 - 10.5 | 9.70 |
| CAPS | 9.7 - 11.1 | 10.40 |
| CABS | 10.0 - 11.4 | 10.70 |