Indicator Acid Color Low pH High pH Base Color Methyl violet yellow 0.0 1.6 blue Cresol red (1st range) red 0.0 1.8 yellow Crystal violet yellow 0.0 1.8 blue Malachite green yellow 0.2 1.8 blue-green Methyl green yellow 0.2 1.8 blue Metanil yellow red 1.2 2.4 yellow m-Cresol purple (1st range) red 1.2 2.8 yellow Metacresol purple (1st range) red 1.2 2.8 yellow Thymol blue (1st range) red 1.2 2.8 yellow 4-o-Tolylazo-o-toluidine orange 1.4 2.8 yellow Orange IV (Tropeolin 00) red 1.4 3.2 yellow 2,6-Dinitrophenol colorless 1.7 4.4 yellow Benzyl orange red 1.9 3.3 yellow 2,4-Dinitrophenol colorless 2.0 4.7 yellow Benzopurpurine 48 violet 2.2 4.2 red p-Dimethylaminoazobenzene red 2.9 4.0 yellow Bromochlorophenol blue yellow 3.0 4.6 purple Bromophenol blue yellow 3.0 4.6 blue Congo red blue 3.0 5.0 red Methyl orange red 3.1 4.4 yellow Ethyl orange red 3.4 4.8 yellow Bromocresol green yellow 3.8 5.4 blue Resazurin orange 3.8 6.4 violet 2,5-Dinotrophenol colorless 4.0 5.8 yellow Methyl red red 4.2 6.3 yellow Azolitmin (litmus) red 4.4 6.6 blue Alizarin red S yellow 4.6 6.0 red Propyl red red 4.6 6.6 yellow Chlorophenol red yellow 4.6 7.0 red p-Nitrophenol colorless 4.7 7.9 yellow Bromophenol red yellow 4.8 6.8 purple Bromocresol purple yellow 5.2 6.8 purple p-Nitrophenol colorless 5.4 6.6 yellow Bromothymol blue yellow 6.0 7.6 blue Brilliant yellow yellow 6.6 7.8 red Phenol red yellow 6.6 8.4 red m-Nitrophenol colorless 6.6 8.6 yellow Neutral red red 6.8 8.0 yellow Rosolic acid brown 6.9 8.0 red Cresol red (2nd range) yellow 7.0 8.8 red a-Naphtholphthalein brown 7.3 8.7 green Metacresol purple (2nd range) yellow 7.4 9.0 purple m-Cresol purple (2nd range) yellow 7.4 9.2 purple Orange I (Tropeolin ))) No. ) yellow 7.6 8.9 rose Thymol blue (2nd range) yellow 8.0 9.6 blue Phenolphthalein colorless 8.0 10.0 red o-Cresolphthalein colorless 8.2 9.8 red Thymolphthalein colorless 8.8 10.6 blue Alizarin yellow GG yellow 10.0 12.0 orange b-Naphthol violet yellow 10.0 12.0 violet Alizarin yellow R yellow 10.1 12.2 red Nitramine colorless 10.8 13.0 brown Poirrier blue blue 11.0 13.0 red Resorcin yellow (Tropeolin 0) yellow 11.1 12.7 orange Benzene sulfonic acid yellow 11.4 12.6 orange Indigosulfonic acid blue 11.4 13.0 yellow Clayton yellow yellow 12.2 13.2 amber   pH values are approximate values and have been rounded off to the nearest tenth. Values assume a temperature of 25 C (77 F)