Free A/B test calculator — enter visitors and conversions for two variants to calculate statistical significance, p-value, confidence level, and conversion lift. Uses a Z-test for two proportions with 95% confidence interval.
How to Use
Enter visitor and conversion counts for Variant A (control).
Enter visitor and conversion counts for Variant B (test).
Click "Calculate" to see statistical significance results.
Review the lift, p-value, confidence level, and winner declaration.
Rate: —
Rate: —
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Relative Lift
—
P-Value
—
Confidence
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Significant?
A: 0%
B: 0%
Formula Explanation
Z-test for two proportions:
p̂A = conversions_A / visitors_A
p̂B = conversions_B / visitors_B
p̂pool = (conversions_A + conversions_B) / (visitors_A + visitors_B)
SE = √( p̂pool × (1 − p̂pool) × (1/nA + 1/nB) )
Z = (p̂B − p̂A) / SE
P-value = 2 × (1 − Φ(|Z|)) (two-tailed)
If p-value < 0.05 → statistically significant at 95% confidence.