CTR (click-through rate)

Click-through rate is the share of people who saw an ad and clicked it: clicks divided by impressions.

40 clicks from 5,000 impressions is a 0.8% CTR. It is the main signal of whether an ad's message lands with the people seeing it.

On small campaigns a CTR is an estimate with a wide margin. Before comparing yours with a benchmark, check the range the true rate could sit in.