Is your A/B test actually real?
Before you call a winner, check the math. Enter each variant's traffic and conversions — get the lift and whether it's statistically significant.
Variant A (control)
Variant B (test)
Inside Slap Post, Chad tracks which of your real posts actually pulled followers — your own running A/B test — and Slap Magic queues the proven winners into your best slots, hands-free.
What is the AB Test Calculator?
The AB Test Calculator is a free statistical significance calculator that tells you whether the difference between two variants is real or just random noise. Enter the visitors and conversions for variant A (your control) and variant B (your test), and this AB test significance calculator runs a two-proportion z-test to return each conversion rate, the relative lift, and the statistical confidence behind it. It is the fastest way to know if you can trust a winner before you ship it — no spreadsheet formulas, no login, no stats degree required.
How to use it
- Enter the total visitors and conversions for variant A, your control.
- Enter the visitors and conversions for variant B, your test variant.
- Tap "Check significance" to see conversion rates, relative lift and your statistical confidence — and a plain-English verdict on whether to ship.
Frequently asked questions
What counts as statistical significance in an A/B test?
Most teams call a result significant at 95% statistical confidence (a p-value of 0.05 or lower). This AB test calculator uses a two-proportion z-test, so 95% confidence means there is only a 5% chance the lift you see is random noise.
How many visitors do I need before I can trust the result?
There is no fixed number — it depends on your baseline conversion rate and the size of the lift. Small lifts need far more traffic. Keep this AB test significance calculator open and stop the test once confidence crosses 95% and both variants have a few hundred conversions.
What is relative lift versus absolute lift?
Absolute lift is the raw difference between the two conversion rates (5% to 6% is +1 point). Relative lift is that change as a percentage of the original (5% to 6% is a +20% relative lift). This statistical significance calculator reports relative lift because it reflects real-world impact.
Is this AB test calculator free?
Yes. It runs entirely in your browser, needs no login or signup, and never stores your numbers. It is completely free to use.
More free tools for X creators: Engagement Rate Calculator · LTV : CAC Calculator · all 30 free tools. Or try Slap Post to schedule and post your content automatically.