How many pH units change are usually required for an indicator to undergo a color change?

Thanks.How many pH units change are usually required for an indicator to undergo a color change?
It depends on the sensitivity of the indicator you are using. There should be a guide with the indicator you are using. Litmus paper, which is the most common form of pH indicator, will change fairly constant across the pH scale, but a neutral (pH 7+/- 0.5 about) solution will normally not cause a change.