Page "PH indicator" Paragraph 6

The equation, derived from the acidity constant, states that when pH equals the pKa value of the indicator, both species are present in 1: 1 ratio.

If pH is above the pKa value, the concentration of the conjugate base is greater than the concentration of the acid, and the color associated with the conjugate base dominates.

If pH is below the pKa value, the converse is true.