Click-through rate is the share of people who saw an ad, email or listing and clicked it. Enter clicks and impressions below.
CTR calculator
Enter any two related numbers and the matching metric fills in: spend and impressions give CPM, clicks and impressions give CTR, spend and clicks give CPC.
2,340 clicks on 180,000 impressions is a 1.3% click-through rate. The same formula works for email if you swap impressions for delivered emails, or for search listings.
Use the right denominator. For ads it's impressions. For email it's usually delivered messages, though some tools report clicks against opens instead. Those give different numbers for the same send, so compare like with like.
CTR is a signal about the creative and the targeting together. If it's low, the ad isn't earning the click, or it's reaching people who never wanted the product. If it's high but sales don't follow, the problem has usually moved to the landing page or the offer.
Holding CPM steady, doubling CTR halves your cost per click, because the same money buys the same impressions and twice as many of them turn into visits. On platforms with an auction, a strong CTR can also make the platform more willing to show your ad, which can pull CPM down as well.
That's why changing the creative is often a cheaper fix than changing the budget. To see the effect on your own numbers, put the same spend and impressions through the CPC calculator after each change.
Same $10 CPM, different CTR
Illustrative arithmetic