Test a bigger change
Small tweaks produce small lifts, and small lifts need huge samples: halving the lift you want to detect roughly quadruples the impressions needed. Test a new first screenshot, message, or style, not a color tweak.
Free developer tool · Updated September 2026
App Store A/B Test Duration Calculator
Find out how long a Product Page Optimization test needs before a variant can reach Apple’s 90% confidence, and whether it can finish inside the 90-day limit.
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Planned for 90% confidence
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How long will your test take?
About Apple’s Product Page Optimization
Apple doesn’t publish the exact statistical method behind Product Page Optimization. This is a planning estimate using a standard two-proportion test at 90% confidence and 80% power.
How it’s calculated
- p₁ is your current conversion rate, and p₂ = p₁ × (1 + lift) is the rate you want to detect.
- Impressions needed by each version (the original and every treatment), with zα = 1.645 for 90% confidence (two-sided) and zβ = 0.8416 for 80% power:
n = (zα + zβ)² × (p₁(1 − p₁) + p₂(1 − p₂)) / (p₂ − p₁)² - Each treatment gets daily impressions × traffic share ÷ treatments per day. The original gets daily impressions × (1 − traffic share).
- The duration is the number of days the slower of the two needs to collect n impressions, rounded up.
- The smallest detectable lift is the lift whose n fits into 90 days of the slower version’s impressions.
- A test finishes soonest when it gets treatments ÷ (treatments + 1) of your traffic: 50% for one treatment, 67% for two, 75% for three.
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Test too slow?
Three ways to finish a test sooner
Duration depends on how big the difference is, how many ways you split your traffic, and how much traffic you have. Change any of them and the estimate above moves.
Test fewer variants
Every extra treatment takes a share of the traffic. With modest traffic, run one bold treatment against the original, then test the next idea against the winner.
Send more traffic to the test
Raise the share of visitors in the test and include every localization that uses the same screenshots. Promoting the app while the test runs helps too.
From plan to live test
Build your test variants in minutes
Screenshot Studio makes new screenshot variants fast, exports every size and localization, and uploads them straight into a Product Page Optimization treatment in App Store Connect.