Test calculator
Can your traffic read a test?
Before you split test a page, check whether your traffic can finish the test. Put in your own numbers.
Purchases needed per version
Visitors needed per version
Weeks to finish at a 50/50 split
Readable. This test can finish inside six weeks.
Too slow. Test a bigger change, or send more of your ad traffic to this page.
Two versions, 95% confidence, 80% power. A rule of thumb for planning, not a replacement for a test plan.
Why this matters
A button colour moves too little to read at most brands' traffic. A page that carries the ad's story can move enough, which is why every test I run is a big swing: the first screen after the click, the page itself, the offer, or what she's offered after she buys.
Not sure which test is worth your traffic?
Send me your best ad. You get it back free, mapped to the page it lands on, with the break marked.