Email A/B Test Calculator — online, free
You sent two versions of an email, one subject line got a few more opens, and now you're wondering whether it actually worked or just got lucky on the day. Sending count is small enough that a couple of extra clicks can fool you. We added a free tool that checks it for you — Email A/B Test Calculator — right in your browser.
What it does
You enter how many emails you sent for each variant and the result you're measuring — replies, opens, or clicks. The calculator works out the rate for each version, the difference between them, and tells you whether that difference is statistically real or could easily be down to chance. So instead of guessing, you find out if variant B genuinely beat variant A.
Nothing leaves your device
The whole thing runs in your browser. Your numbers aren't uploaded anywhere, nothing is saved, and there's no sign-up. Close the tab and it's gone.
How to use it
- Open Email A/B Test Calculator and type in the emails sent for variant A and variant B.
- Enter the result you're testing — replies, opens, or clicks — for each one.
- Read the answer: the rates, the gap, and whether the winner is real.
It's free with no limit. There are more small tools on the Apps page.