# Free CRO and A/B Testing Calculators | George Peric
URL: https://www.cro-designer.com/tools
Last updated: 2026-10-26

> Free CRO and A/B testing calculators: CRO ROI, A/B test sample size, statistical significance and sample ratio mismatch (SRM). Private, in your browser.

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Free CRO and A/B testing tools

## Free tools to plan, read and price your tests.

The calculators I use myself: what a conversion lift is worth, how long a test must run, whether a winner is real and whether the traffic split is broken. Free, private and in your browser.

### CRO ROI calculator

See what a conversion lift is worth per month and per year for your store or lead gen site.

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### A/B test sample size calculator

How many visitors and how many days your test needs before you can trust the result.

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### A/B test significance calculator

Is your winner real or just noise? Get the p-value, the lift and its confidence interval.

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### SRM checker

Check if your traffic split matches what you set. A mismatch means the test can’t be trusted.

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### Let’s make your next test a winner.

Tell me about your funnel. I’ll point out quick wins, tell you what I’d test first, and say honestly whether I’m the right fit.

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