A/B Test Duration Calculator
Free CalculatorEstimate how many days your A/B test needs to run to reach your target sample size.
100% private
Runs in your browser β no numbers leave your device.
Your numbers
Users needed in each variant to reach significance (from your sample-size calculator).
Include the control β a classic A/B test has 2.
How many people enter the test each day, across all variants.
Test duration (days)
10
Total sample Γ· daily visitors.
Weeks
1.4
Round up to full weeks to smooth out weekday effects.
How it works
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Ship stronger variants to test
Reverze generates A/B screenshot variants so you always have a stronger version to test
How long should you run an A/B test?
A/B test duration comes down to simple math: how many users you need versus how fast they arrive. This calculator multiplies your sample size per variant by the number of variants, then divides by your daily visitors to tell you how many days β and weeks β the test should run.
Pair it with a sample-size calculator to get the per-variant number first, then bring it here. Running long enough to hit that sample is what makes your winner trustworthy instead of a coin flip, so resist calling the test early even when an early lead looks tempting.