Expressed as a percentage of total impressions, this statistic shows how often people who are served an ad end up clicking on it.An ad’s CTR is calculated by dividing the number of clicks an ad received by the number of times it’s been served, then converting that into a percentage. For example, if an ad received 5 clicks and was shown 1000 times, the CTR is 0.5%. The higher the CTR on an ad, the better it’s performing.