Clickthrough rate (CTR) formula

Clickthrough rate (CTR) formula – A ratio showing how often people who see your ad end up clicking it. CTR can be used to gauge how well your keywords and ads are performing.

CTR is the number of clicks that your ad receives divided by the number of times your ad is shown expressed as a percentage (clicks ÷ impressions = CTR).For example, if you had 5 clicks and 1000 impressions, then your CTR would be 0.5%. Here’s how it’s calculated:
Each of your ads and keywords have their own CTRs that you can see listed in your account. Find them on your Campaigns tab
A high CTR is a good indication that users find your ads helpful and relevant. CTR also contributes to your keyword’s expected CTR (a component of Quality Score), which can affect your costs and ad position. Note that a good CTR is relative to what you’re advertising and on which networks.
You can use CTR to gauge which ads and keywords are successful for you and which need to be improved. The more your keywords and ads relate to each other and to your business, the more likely a user is to click on your ad after searching on your keyword phrase.