pH Indicator Ranges (Ascending pH)
Acid-base pH indicators are solutions that have a characteristic color at certain pH levels. They are used to visually signal the acidity or alkalinity of an aqueous (water-based) solution. pH indicators generally change color over a range of two pH units. They work only in colorless solutions in which a color change can be observed and can only give an approximate pH value. The table below gives a list of common laboratory pH indicators.
| pH Range | Indicator |
| 0.2 (red) - 1.8 (yellow) and 7.2 (yellow) - 8.8 (red) | Cresol Red |
| 1.2 (red) - 2.8 (yellow) and 7.4 (yellow) - 9.0 (purple) | Cresolphthalein (meta) |
| 1.2 (red) - 2.8 (yellow) and 7.4 (yellow) - 9.0 (purple) | Cresol Purple |
| 1.2 (red) - 2.8 (yellow) | Thymol Blue |
| 2.9 (purple) - 4.6 (green) | Methyl Orange - Xylene Cyanol |
| 3.0 (yellow) - 4.6 (blue) | Bromophenol Blue |
| 3.0 (blue) - 5.0 (red) | Congo Red |
| 3.0 (red) - 6.3 (yellow) | Methyl Orange |
| 4.0 (red) - 5.6 (yellow) | Alizarin Red S |
| 4.0 (yellow) - 5.6 (blue) | Bromocresol Green |
| 4.0 (colorless) - 6.6 (green) | Dichlorofluorescein |
| 4.2 (pink) - 6.2 (yellow) | Methyl Red |
| 4.6 (pink) - 5.2 (blue/green) | Bromocresol Green / Methyl Red |
| 5.2 (yellow) - 6.6 (purple) | Bromocresol Purple |
| 5.2 (yellow) - 6.8 (red) | Chlorophenol Red |
| 6.0 (yellow) - 7.6 (blue) | Bromothymol Blue |
| 6.8 (yellow) - 8.2 (red) | Phenol Red |
| 7.3 (colorless/reddish) - 8.7 (blue/green) | Naphtholphthalein (alpha) |
| 8.0 (colorless) - 10 (pink) | Phenolphthalein |
| 8.2 (colorless) - 9.8 (violet/red) | Cresolphthalein (ortho) |
| 8.8 (colorless) - 10.5 (blue) | Thymolthalein |
| 11.6 (blue) - 14.0 (yellow) | Indigo Carmine |
