A/B Test Statistical Significance Calculator
Find out if your test results are statistically significant or if you need more data before making a decision.
Quick start: Enter your test results below to see if you have a clear winner or need to keep testing.
Confidence Level
0%
Improvement
0%
P-Value
0
Recommendation
Quick start: Find out how many visitors you need before starting your test. This prevents wasting time on tests that can't give you reliable results.
Sample size needed per variant
0
Total visitors needed: 0
Estimated test duration
0 days
Based on your daily traffic
Testing Tips:
- • Don't stop your test early, even if results look promising
- • Run tests for at least 1-2 full business cycles (weeks)
- • Test one variable at a time for clearer insights
- • Make sure your sample includes different days/times
Understanding Statistical Significance
Statistical significance tells you whether your A/B test results are real or just due to random chance. A statistically significant result means you can be confident that the difference between variants is genuine.
What do the numbers mean?
Confidence Level
How confident you can be in your results. 95% means there's only a 5% chance the results are due to random variation.
P-Value
The probability that your results occurred by chance. Lower is better. Below 0.05 is considered statistically significant.
Sample Size
The number of visitors needed in each variant. Smaller effects require larger sample sizes to detect reliably.
Common mistakes to avoid
- Stopping tests too early: Even if variant B is winning, you need enough data for statistical significance
- Testing too many things at once: Test one variable at a time to understand what's driving changes
- Ignoring external factors: Holidays, promotions, or seasonal changes can skew results
- Testing on too small traffic: Low-traffic sites need longer test durations or larger effect sizes
Want to run more effective A/B tests? Our CRO services can help you design, implement, and analyze tests that drive real business results.
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