Click-to-Open Rate Calculator
Calculate your click-to-open rate (CTOR) to measure how compelling your email content is.
What is click-to-open rate?
Click-to-open rate (CTOR) is clicks divided by opens - it measures how compelling your content and call to action are among the people who actually opened. Unlike click-through rate (clicks over delivered), CTOR isolates content effectiveness from subject-line and deliverability effects.
In other words, open rate tells you whether the subject line and sender earned attention; CTOR tells you whether the message earned action once someone was looking. A high open rate with a low CTOR means the subject over-promised and the body under-delivered.
CTOR for cold email
For cold email specifically, treat CTOR as a diagnostic rather than a headline metric. Open tracking is already unreliable (Apple Mail Privacy Protection inflates opens), and many cold emails deliberately carry zero or one links, so a raw click metric can be thin.
Where CTOR earns its keep is A/B testing body copy and calls to action on the same audience: hold the subject constant, change the offer or the ask, and watch which version turns more of the same openers into clicks or replies. The real north-star for cold outreach remains positive reply rate.
Frequently asked questions
How is CTOR calculated?
CTOR = (unique clicks / unique opens) x 100. It measures content and call-to-action strength among openers.
How is CTOR different from CTR?
CTR (click-through rate) divides clicks by delivered emails; CTOR divides clicks by opens. CTOR removes the subject-line and deliverability effect and isolates how compelling the content is.
What is a good CTOR?
It varies widely by audience and email type, so compare against your own baseline rather than a universal number. A high open rate paired with a low CTOR is the signal worth acting on - it means the body isn't delivering on the subject's promise.
Is CTOR useful for cold email?
As a diagnostic, yes - especially for A/B testing body copy and calls to action on the same audience. But because open and click tracking are unreliable for cold email, positive reply rate is the metric to optimize toward.
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