What is the formula to find CTR ?
CTR is the number of clicks that your ad receives divided by the number of times your ad is shown: clicks ÷ impressions = CTR.
Click-through rate, or CTR, is determined by how many times a user clicks on an ad or a link and arrives at the designated page.
For example, if you had 5 clicks and 100 impressions, then your CTR would be 5%. Each of your ads and keywords have their own CTRs that you can see listed in your account.