How to use the email click-to-open rate calculator
Click-to-open rate (CTOR) answers what share of the people who opened your email went on to click. Because the denominator is opens, it measures the body copy and the call to action rather than the subject line. Plain click-through rate (CTR) divides by emails sent or delivered instead, so it bundles subject line, send timing and list quality into one number.
This calculator shows both and writes the denominator into each label. Enter a delivered count and the open rate and CTR switch to that denominator, with the labels updating to match; leave it blank and emails sent is used. If open rate climbs while CTOR stays flat, the subject line worked and the body did not. The reverse pattern points at deliverability instead.
Opens are usually counted by loading a tracking pixel, so mail apps that pre-fetch images or proxy them for privacy can inflate the figure. An inflated open count pushes CTOR down, which is why trends on the same list are safer to read than absolute values. What counts as healthy varies by industry and list, so no benchmark is built in: enter your own target CTOR and the tool reports only the gap to it.
Frequently asked questions
They answer different questions. Use CTOR when iterating on body copy and CTAs, and CTR when judging overall campaign performance or list quality. Reading both narrows down where the drop-off happens.
That usually means total clicks were paired with unique opens. One person clicking several links inflates the total, so use unique clicks and unique opens together.