Free Tools

Plan better experiments, starting now

Six free calculators used by CRO specialists and marketing teams to plan, validate, and measure A/B tests. No signup. No tracking. Runs entirely in your browser.

A/B Test Sample Size Calculator

Stop guessing how much traffic you need. Enter your baseline conversion rate and minimum detectable effect — get the exact sample size for a valid test.

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A/B Test Duration Calculator

Know exactly when to call your test. Input your daily traffic and goals — see how many days you need before results are trustworthy.

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Statistical Significance Calculator

Did your variant actually win? Paste your control and variant numbers — get a clear confidence level and p-value in seconds.

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CRO ROI Calculator

Prove the revenue impact of optimization work. Enter your traffic, conversion rate, and projected lift — see the monthly and annual dollar impact.

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Cart Abandonment Calculator

Find out how much revenue you're leaving on the table. Calculate your abandonment rate and see how much you can recover with targeted interventions.

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UTM Campaign Link Builder

Build trackable campaign URLs in seconds. Add source, medium, and campaign tags — copy the link and paste it into your ads, emails, or social posts.

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Go beyond calculators

Run the tests these tools help you plan.

Humblytics combines visual A/B testing, heatmaps, funnel analytics, and agent-powered recommendations — so you can go from calculating sample sizes to launching winning experiments in minutes.