CTR (click-through rate)
Click-through rate tells you how many of the people who saw your ad or search result cared enough to click. It is the first sign of whether your message fits the people seeing it.
What CTR means
CTR is clicks divided by impressions. If an ad is shown 1,000 times and gets 15 clicks, its CTR is 1.5%. It measures the step between being seen and being visited: the hook, the image, the offer, and how well the ad matches the person in front of it.
Platforms count clicks in different ways. Meta reports link clicks and all clicks, and all clicks include likes, profile taps and opening the image, so the two numbers can be far apart. Decide which one you use and keep it the same whenever you compare ads.
The formula
CTR = clicks ÷ impressions × 100
Clicks = impressions × CTR
Cost per click (CPC) = CPM ÷ (1,000 × CTR), with CTR written as a decimal (1.5% = 0.015)
A worked example
Go back to the bakery from the CPM page: $300 bought 60,000 impressions, a CPM of $5. The ad got 600 link clicks, so CTR is 600 ÷ 60,000 = 1%, and each click cost 300 ÷ 600 = $0.50. The bakery and its numbers are made up for this example.
The bakery then tests a second ad that opens with a photo of bread coming out of the oven at 7 a.m. Same budget, same audience, CPM still $5, but 900 clicks: CTR is 1.5% and a click now costs about $0.33. Nothing changed in the auction. The ad simply gave more people a reason to stop scrolling.
How to read it
A CTR that keeps falling on an ad that used to work often means the same people have seen it too many times. Check frequency before you rewrite the ad.
On search ads, CTR also shows whether your keywords match what people are looking for. Google uses expected CTR as one part of Quality Score, so a relevant ad can end up paying less per click than a vague one in the same auction.
As with CPM, there is no universal good CTR. Compare against your own earlier ads on the same platform and placement.
Three mistakes to watch for
Treating a high CTR as success. A curiosity headline can earn plenty of clicks from people who leave the page at once. Judge an ad by what happens after the click as well.
Changing several things at once. If you change the image, the headline and the audience in one go, you will not know which of them moved CTR.
Picking a winner too early. Three clicks from 100 impressions is a 3% CTR, but it tells you almost nothing yet. Let each ad collect a few thousand impressions before you compare them.