The click through rate is calculated by dividing the number of clicks by the number of impressions (times the ad or link was seen) and then multiplying by 100 to get a percentage. The formula is: CTR (%) = (Clicks / Impressions) x 100 For example, if an ad was shown 1,000 times and received 50 clicks, the CTR would be: CTR = (50 / 1000) x 100 = 5%