Duration Calculator
How long does your test need to run? Plug in the numbers, find out.
Test Setup
Visits to the test location per day
Success Metrics
Per-Metric Estimates
Parameters
- Daily Visits
- —
- Variations
- —
- Confidence
- 95%
- Power
- 80%
- Correction
- Bonferroni
Uses the standard two-sample z-test for proportions. The same methodology Adobe Target's Sample Size Calculator uses under the hood, not a simplified or proprietary version.
Formula: n = (Z_α/2 + Z_β)² × [p₁(1−p₁) + p₂(1−p₂)] / (p₂ − p₁)²
Defaults: 95% confidence (α = 0.05), 80% power (β = 0.20). Duration = total sample size ÷ daily visits, rounded up to the next full week.
Multiple comparisons: When enabled, applies Bonferroni correction α_adj = α / (V−1) to maintain family-wise error rate across multiple variation comparisons. Turn this on when you have three or more variations and want to avoid false positives from repeated testing.