Open Rate vs Click-Through Rate: What's the Difference?

Open rate is the share of delivered emails that were opened, a proxy for how well the subject line, sender name, and send time got a recipient to engage before reading any of the actual content.

Click-through rate (CTR) is the share of delivered emails (or, in some reporting, opened emails) where a recipient clicked a link inside the message, a proxy for whether the body content, offer, and call to action were compelling enough to act on.

The two numbers can move independently, and when they do, each points somewhere different. A high open rate paired with a low CTR usually means the subject line worked but the content or offer inside didn't land - the fix is to the body, not the send. A low open rate with a strong CTR among the people who did open suggests the opposite: the content is fine, but too few people are seeing it, so the fix is to the subject line, sender reputation, or send timing. Open rate has also become a noisier signal since Apple's Mail Privacy Protection and similar inbox-provider features began pre-fetching images and inflating opens automatically, which is part of why CTR, and click-to-open rate (clicks divided by opens) specifically, has become the more trusted measure of whether an email actually worked.