Evan's Awesome A/B Tools (home):

Sample Size Calculator  |  Chi-Squared Test  |  Sequential Sampling  |  2 Sample T-Test  |  Survival Times  |  Count Data

Question: How many conversions are needed for a sequential A/B test?

[ link ]
Baseline conversion rate: %
Minimum Detectable Effect: %
0% – 1.2%
The Minimum Detectable Effect is the smallest effect that will be detected (1-β)% of the time.
Conversion rates in this range will not be distinguishable from the baseline (one-sided test).
Control wins if:
total conversions
Treatment wins:
conversions ahead
Statistical power 1−β:
Percent of the time the minimum effect size will be detected, assuming it exists
Significance level α:
Percent of the time a difference will be detected, assuming one does NOT exist

See also: Simple Sequential A/B Testing

If you like this, check out Wizard — the easy Mac statistics app.