Acid / Base Indicators
IndicatorLower ColorpH RangeUpper Color
methyl violetyellow-green0.0 - 2.5violet
methyl orangered2.5 - 4.4yellow
congo redblue3.0 - 5.0red
bromocresol greenyellow4.5 - 5.5blue
methyl redred4.8 - 6.0yellow
bromocresol purpleyellow-green5.4 - 6.8violet
bromothymol blueyellow6.0 - 7.6blue
phenol redyellow6.4 - 8.2red-violet
cresol redyellow7.1 - 8.8violet
phenolphthaleincolorless8.3 - 10.0dark pink
Phenolphthalein is a common indicator to use in neutralization titrations. The solution is considered neutral when it holds a very faint pink color for half a minute or more.

Phenolphthalein Color Chart
colorless in an acid
pH below 7
faint pink in a neutral solution
pH = 7
dark pink in a base
pH above 7
alizarin yellow Ryellow9.9 - 11.8dark orange


A solution with a wide range of color changes.


A paper that goes through changes similar to the universal indicator solution.


Red litmus paper turns blue in a base.

Blue litmus paper turns red in an acid.

There is a litmus liquid with similar color response.