What is click-to-open rate (CTOR)?
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Open rate tells you how many people opened your email. Click-to-open rate (CTOR) goes one step further: of the people who opened, how many actually clicked something?
CTOR is calculated as unique clicks divided by unique opens, multiplied by 100. So if 1,000 people opened your email and 80 clicked, your CTOR is 8%.
Think of it as a content quality signal. It removes the "did my subject line work?" question and focuses on "once people were inside, did they engage?" That's useful when you're testing copy, CTAs, or email layouts, because it isolates the content variable from the delivery variable.
There's one caveat worth knowing: CTOR relies on open data, which has been unreliable since Apple Mail Privacy Protection started pre-fetching tracking pixels in 2021. If your reported opens include a lot of machine-triggered opens, your CTOR will look artificially low. The metric is still useful for comparing campaigns to each other, just not for absolute benchmarking against industry averages.
For the complementary view, click-through rate (CTR) measures clicks across your whole delivered list, not just the openers.
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