Variant B shows 20% relative uplift and the calculator reports whether it clears 95% confidence.
Marketing calculator
A/B Test Significance Calculator
Check whether an observed A/B conversion difference is larger than the random variation expected by this model.
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No account. Formula and assumptions are shown below.
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A/B test significance details
Formula & disclaimer
Z = (Conversion Rate B β Conversion Rate A) Γ· Pooled Standard Error; two-sided p-value uses the standard normal distribution
View assumptionsFormula reviewCalcs at Hand Editorial TeamVerified 1 September 2026 Β· automated checks included
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Resultβ
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Formula & details
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How to read this result
Three useful checks, kept deliberately short.
250 of 5,000 visitors convert in A and 300 of 5,000 convert in B: Calculate both conversion rates Β· Estimate the pooled standard error Β· Compare the two-sided p-value with 5%.
Statistical significance does not measure business value, test quality or whether repeated peeking affected the result.
Formula and assumptions
Z = (Conversion Rate B β Conversion Rate A) Γ· Pooled Standard Error; two-sided p-value uses the standard normal distributionThe two-proportion z-test assumes independent observations and one conversion outcome per visitor.
Keep in mind: This normal-approximation test is not suitable for every experiment design, small sample or repeated interim analysis.
Produced byCalcs at Hand Editorial Team
Last formula check1 September 2026
Review methodKnown examples + boundary cases
Editorial and correction policy β