
A/B Testing Calculator
Sample size & significance
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Free
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About
A/B Testing Calculator helps you plan and evaluate A/B tests: work out how many users you need for a reliable result, and find the test winner with statistical significance in mind.
BEFORE THE TEST — SAMPLE SIZE
Set your baseline rate, expected uplift, reliability and power — and the app calculates how many people should see each variant. Works for open rate, click rate and order conversion.
AFTER THE TEST — RESULTS
Enter the number of conversions and the sample size for each variant (up to 5) — the app shows conversion rates, confidence intervals and a clear verdict: which variant is better and whether you can trust the result.
FEATURES
• Two calculators: sample size and results evaluation
• Compare up to 5 variants at once
• Confidence intervals and statistical-significance testing
• Clear explanations without statistical jargon
• Copy any result with one tap
Great for marketers, product managers and analysts.
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What's New in A/B Testing Calculator
1.5
July 14, 2026
Enter conversions as percentages. On the Test results screen, each variant's conversions can now be entered the way your report shows them — as a raw count or as a percentage. Your input stays exactly as typed: change the sample size and the app recalculates the other value, never the one you entered. Clearer error messages when entering percentages, and small polish throughout.
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