Free confidence interval calculator
Free confidence interval calculator
Free confidence interval calculator
Know if your winner is really winning
See the true range behind your results
Enter visitors and conversions for each variant. We'll compute the lift, P-value, and confidence interval — and tell you whether the result is statistically significant.
Instantly calculate the confidence interval around a proportion or mean. Know exactly how much your survey result could vary in the real world.
Enter visitors and conversions for each variant. We'll compute the lift, P-value, and confidence interval — and tell you whether the result is statistically significant.
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PROPORTION CONFIDENCE INTERVAL
53.21% – 66.79%
95% confidence · z = 1.96 · p̂ = 60.00%
60.0%
0%100%
HOW TO READ IT
Intervals in plain language
1
If you repeated your survey many times, 95% of those intervals would capture the true value.
2
Narrower intervals come from larger samples or accepting lower confidence.
3
Use the proportion tab for yes/no results (e.g. satisfaction %). Use mean for average scores (e.g. 1–5 ratings).
The interval shows where the true population value likely sits. Wider intervals mean more uncertainty — usually caused by smaller samples or lower confidence levels.
The interval shows where the true population value likely sits. Wider intervals mean more uncertainty — usually caused by smaller samples or lower confidence levels.
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