A/B Test Significance Calculator

Most declared winners aren't. With small sample sizes a 20% "lift" is routinely just noise. Enter both variants to see the confidence level before you roll anything out.

Variant A — visitorsVariant A — conversionsVariant B — visitorsVariant B — conversions

Estimates only — edit any field to match your real numbers.

Your results

Confidence B beats A

94.1%

Variant A rate

3.00%

Variant B rate

3.90%

Relative lift

30.0%

Want real results instead of estimates? Let us run your Conversion Rate Optimization.

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Frequently asked questions

What confidence level should I wait for?+

95% is the usual bar. Below 90%, the honest reading is that you don't know yet — keep the test running rather than declaring a winner.

Is this tool really free? Do I need an account?+

Free, and no account. Everything runs in your browser — we never see your numbers unless you press save to create a shareable link.

Next, work out

CPM, CPC & CTR Calculator

Enter spend, impressions and clicks to get CPM, CPC, CTR, conversion rate and cost per acquisition. Free ad metrics calculator in KWD.

Conversion Rate Calculator

Calculate conversion rate, revenue per visitor and what hitting a benchmark rate would be worth to you in KWD. Free tool.