For standard ads, your ad clickthrough rate (CTR) is the number of ad clicks divided by the number of individual ad impressions.
Ad CTR = Clicks / Ad impressions
For example, if your ad received 5 clicks out of 1000 ad impressions, your ad CTR would be .5%.
For link units, the number of ad clicks divided by the number of impressions for the page of ads that appears when a link unit is clicked.
Note that this metric is only available under the "Custom" metric family tab. Learn more about the custom metric family.
