Click-through rate
The share of people who saw a placement and clicked it, calculated as clicks divided by impressions of that same placement.
Updated August 14, 2026
Click-through rate, usually written CTR, is clicks divided by impressions for one placement over one period: an email opened a thousand times and clicked fifty times has a CTR of five per cent. It measures the invitation — the subject line, the creative, the button — and nothing that happens after it.
A link platform can only supply the numerator. Impressions belong to the channel that showed the link: the mail tool, the ad account, the social platform. So CTR is always assembled from two sources, which makes the denominator the part worth double-checking — sends, delivered messages and opens produce three different rates from the same clicks, and comparing a campaign measured one way against a campaign measured another is the most common way the metric misleads.
The second trap is treating a high CTR as success. A curiosity headline lifts clicks and can lower revenue. Judge the invitation by CTR, then judge the offer by conversion.