# ABFinal

> Free A/B testing calculators that run in your browser: sample size, significance, Bayesian probability to beat, test duration, SRM, price tests and X post tests.

ABFinal is a free, independent toolkit. Every calculator runs in the visitor's browser; nothing typed into a calculator is sent to a server. Formulas and reference values are documented on the methodology page.

## Calculators

- [A/B Test Sample Size Calculator](https://abfinal.com/tools/sample-size-calculator): Free A/B test sample size calculator. Enter your baseline conversion rate and minimum detectable effect to get visitors per variant, with power and multi-variant options.
- [A/B Test Significance Calculator (Frequentist and Bayesian)](https://abfinal.com/tools/significance-calculator): Free A/B test significance calculator. Two-proportion z-test p-value, confidence interval for the lift, and exact Bayesian probability that B beats A, side by side.
- [A/B Test Duration Calculator](https://abfinal.com/tools/test-duration-calculator): Free A/B test duration calculator. Enter daily visitors, baseline conversion and the lift you want to detect to see how many days and full weeks your test needs.
- [Minimum Detectable Effect (MDE) Calculator](https://abfinal.com/tools/mde-calculator): Free minimum detectable effect calculator. Enter visitors per group or weekly traffic and weeks to see the smallest lift your A/B test can reliably detect.
- [Sample Ratio Mismatch (SRM) Checker](https://abfinal.com/tools/srm-checker): Free sample ratio mismatch checker. Enter visitors per group and the planned split to run a chi-square test and find out whether your A/B test traffic split is broken.
- [Price Test Calculator (Revenue and Profit per Visitor)](https://abfinal.com/tools/price-test-calculator): Free price test calculator: compare two prices on conversion, revenue per visitor and gross profit per visitor, with the break-even conversion for the new price.
- [A/A Test Simulator (See What Peeking Does)](https://abfinal.com/tools/aa-test-simulator): Free A/A test simulator. Run thousands of simulated tests with no real difference to see the false positive rate, and how checking results early inflates it.
- [X Post A/B Comparer (Engagement Rate Significance)](https://abfinal.com/x/tweet-ab-test-calculator): Free tweet A/B test calculator. Enter impressions and engagements for two X posts to compare engagement rates with a significance test and a Bayesian probability.
- [X Post Variant Planner](https://abfinal.com/x/tweet-variant-planner): Free X post variant planner. Work out how many impressions and posts you need to compare two tweet styles, get a balanced AB/BA schedule and check each draft's length.

## Guides and comparisons

- [Free A/B Testing Calculators](https://abfinal.com/tools): Seven free A/B testing calculators: sample size, significance with Bayesian probability, test duration, MDE, SRM checker, price test profit and an A/A simulator.
- [A/B Testing on X (Twitter)](https://abfinal.com/x): Free tools for testing posts on X (Twitter): compare the engagement rates of two posts for significance, plan a fair variant test and learn a repeatable method.
- [How to A/B Test Posts on X (Twitter)](https://abfinal.com/x/how-to-ab-test-tweets): A practical method for A/B testing posts on X (Twitter): one variable, planned impressions, matched pairs, logged results and a significance check.
- [A/B Testing for Conversion Rate Optimization](https://abfinal.com/a-b-testing-cro): A practical guide to A/B testing for conversion rate optimization: research, hypotheses, sample size, running the test, reading results and building on what you learn.
- [Building a CRO Testing Roadmap](https://abfinal.com/ab-testing-cro): How to build a CRO testing roadmap: collect ideas from research, score them with ICE, check them against your traffic capacity and plan a realistic testing calendar.
- [Price A/B Testing for Online Stores](https://abfinal.com/price-ab-testing): How to run price A/B tests on an online store: choosing price points, judging by profit per visitor, break-even conversion math, sample size, and legal and trust risks.
- [The CRO Guru Checklist - a Self-Serve Store Audit](https://abfinal.com/cro-guru): An interactive CRO checklist for online stores: 24 checks across speed, navigation, product pages, trust, cart and checkout. Fix the basics before testing.
- [AI in A/B Testing - What It Does Well and Where to Be Careful](https://abfinal.com/ai-features): An honest look at AI in A/B testing: generated variants, multi-armed bandits, AI personalization and automated analysis - what each does well and what it can hide.
- [A/B Testing Meta Ads (Facebook and Instagram)](https://abfinal.com/meta-ads): How to A/B test Facebook and Instagram ads: using Meta's A/B test tool, choosing one variable, sizing budget and duration, and reading results without fooling yourself.
- [Snap Pixel and Conversion Tracking for Tests](https://abfinal.com/snap-pixel): What the Snap Pixel does, how to set it up on an online store, how to verify purchase events, and why tracking accuracy decides whether ad tests mean anything.
- [Methodology - Formulas and Reference Checks](https://abfinal.com/methodology): The formulas behind ABFinal's calculators (sample size, z-test, Bayesian probability to beat, SRM, MDE, price break-even) and the reference values we test.
- [ABFinal vs Optimizely](https://abfinal.com/ab-final-vs-optimizely): An honest comparison of ABFinal and Optimizely: what Optimizely's experimentation products do, how its Stats Engine works, pricing model, and where free calculators fit.
- [ABFinal vs VWO](https://abfinal.com/ab-final-vs-vwo): An honest comparison of ABFinal and VWO: what VWO does, its 2026 merger with AB Tasty under the Wingify brand, its pricing model, and where free calculators fit in.
- [ABFinal vs AB Tasty](https://abfinal.com/ab-final-vs-ab-tasty): An honest comparison of ABFinal and AB Tasty: what AB Tasty does, its 2026 merger with VWO under the Wingify brand, its pricing model, and where calculators fit.
- [ABFinal vs Intellimize (now part of Webflow)](https://abfinal.com/ab-final-vs-intellimize): ABFinal vs Intellimize: Webflow acquired Intellimize in 2024 and launched Webflow Optimize. What that means, and where free A/B test calculators fit.
- [ABFinal vs Mutiny](https://abfinal.com/ab-final-vs-mutiny): ABFinal vs Mutiny: from B2B website personalization to a 2026 relaunch as an AI agent for go-to-market teams. What changed, and where calculators fit.

## Blog

- [12 Common A/B Testing Mistakes (and How to Avoid Them)](https://abfinal.com/blog/common-a-b-testing-mistakes): Twelve common A/B testing mistakes, from peeking and small samples to broken splits and metric fishing, and how to avoid each one.
- [A/B Testing for Mobile Shoppers](https://abfinal.com/blog/a-b-testing-for-mobile): A/B testing for mobile shoppers: why lower mobile conversion rates raise sample sizes, what to test on small screens, and how app tests differ from web tests.
- [A/B Testing vs Hypothesis Testing - A Side-by-Side Walkthrough](https://abfinal.com/blog/what-is-ab-testing-vs-hypothesis-testing): A/B testing vs hypothesis testing side by side: a translation table of terms (null hypothesis, alpha, power, MDE) and one store test told in both vocabularies.
- [How Long Does It Take to Run an A/B Test?](https://abfinal.com/blog/how-long-does-it-take-to-run-an-ab-test): How long an A/B test takes: reach your planned sample, run whole weeks (at least one or two) and avoid going past six to eight. Work out your own duration.
- [How Often Should You Run A/B Tests?](https://abfinal.com/blog/how-often-to-do-a-b-testing): How often to run A/B tests: as often as your traffic supports properly sized tests. How to work out your testing capacity and run parallel tests safely.
- [How to Analyze A/B Test Results, Step by Step](https://abfinal.com/blog/how-to-analyze-a-b-test-results): How to analyze A/B test results step by step: check the split, get the p-value and confidence interval, read the Bayesian probability, review guardrails, decide.
- [How to Create a High-Converting Shopify Homepage](https://abfinal.com/blog/how-to-create-a-high-converting-shopify-homepage): How to build a Shopify homepage that converts: say what you sell fast, route visitors to products, show trust, and measure click-through as well as sales.
- [How to Create a User-Friendly Navigation on Shopify](https://abfinal.com/blog/how-to-create-a-user-friendly-navigation-on-shopify): How to build user-friendly Shopify navigation: menus organized by how customers shop, plain labels, search and filters that work, and careful testing.
- [How to Improve Shopify Conversion Rates](https://abfinal.com/blog/how-to-improve-shopify-conversion-rates): How to improve your Shopify conversion rate: measure the funnel, fix speed and trust gaps, improve product pages, cart and checkout, then A/B test the uncertain changes.
- [How to Optimize Site Speed on Shopify](https://abfinal.com/blog/how-to-optimize-site-speed-on-shopify): How to speed up a Shopify store: measure Core Web Vitals, remove unused apps and leftover code, size images properly, and cut fonts and third-party scripts.
- [How to Optimize Your Prices on Shopify](https://abfinal.com/blog/how-to-optimize-your-prices-on-shopify): How to optimize prices on Shopify: work out true unit margins, find the break-even conversion rate, pick a testing approach and judge by profit per visitor.
- [How to Use Retargeting Ads to Boost Shopify Conversions](https://abfinal.com/blog/how-to-use-retargeting-ads-to-boost-shopify-conversions): How to use retargeting ads for a Shopify store: audiences by intent, messages matched to the drop-off point, frequency caps, and a holdout to measure real lift.
- [How to Write SEO-Friendly Product Descriptions on Shopify](https://abfinal.com/blog/how-to-create-seo-friendly-product-descriptions-on-shopify): How to write SEO-friendly Shopify product descriptions: original copy, the words customers search for, scannable specs, and the Shopify fields that matter.
- [Is A/B Testing Really Reliable?](https://abfinal.com/blog/is-ab-testing-really-reliable): Is A/B testing reliable? Well-run tests are the best evidence a business can get, but small samples, peeking, broken splits and metric fishing mislead.
- [Is A/B Testing Worth It?](https://abfinal.com/blog/is-ab-testing-worth-it): Is A/B testing worth it for your store? Traffic thresholds, tool and time costs and the expected value of a test, plus what to do when traffic is low.
- [Is A/B Testing a Strategy?](https://abfinal.com/blog/is-ab-testing-a-strategy): A/B testing is a method, not a strategy. Learn how a real optimization strategy uses research and priorities to decide what to test, and testing to check what works.
- [Is A/B Testing the Same as Hypothesis Testing?](https://abfinal.com/blog/is-ab-testing-the-same-as-hypothesis-testing): A/B testing uses hypothesis testing but isn't the same thing: the experiment adds design, randomization and a decision. Here's how the two relate.
- [Optimizing Product Pages for Higher Conversions](https://abfinal.com/blog/optimizing-product-pages-for-higher-conversions): How to optimize product pages for conversions: what goes above the fold, photos, descriptions, delivery and returns info, reviews, and what's worth testing.
- [Price Testing Strategies for Online Stores](https://abfinal.com/blog/price-testing-strategies): Six price testing strategies for online stores, from straight A/B price tests to sequential tests, bundles and shipping thresholds, with the trade-offs of each.
- [T-Test vs A/B Test - What's the Difference?](https://abfinal.com/blog/t-test-vs-ab-test): A t-test and an A/B test aren't alternatives: the A/B test is the experiment and the t-test one way to analyze it. When a t-test fits and when a z-test is better.
- [The Benefits of A/B Testing (and What It Can't Do)](https://abfinal.com/blog/benefits-of-a-b-testing): The real benefits of A/B testing for online stores: cause-and-effect evidence, lower risk, cheaper growth and customer insight, plus the limits worth knowing.
- [What Are the Possible Outcomes of an A/B Test?](https://abfinal.com/blog/what-are-the-possible-outcomes-of-an-a-b-test): The five possible outcomes of an A/B test - clear winner, clear loser, flat result, inconclusive and invalid - with example numbers and the right next step for each.
- [What Are the Types of A/B Testing?](https://abfinal.com/blog/what-are-the-types-of-ab-testing): The main types of A/B testing: classic A/B, A/B/n, split URL, multivariate, A/A, bandits, server-side and price tests, and when to use each one.
- [What Does A/B Test Analysis Involve?](https://abfinal.com/blog/what-is-the-analysis-of-ab-testing): What A/B test analysis involves: validity checks, the primary metric, effect size and uncertainty, guardrail metrics, and segments used for ideas only.
- [What Is A/B Testing, in Plain English?](https://abfinal.com/blog/what-is-ab-testing-in-layman-terms): A/B testing explained in plain English: show two versions to similar people at the same time, count what they do, and check whether the difference is bigger than luck.
- [What Is the Difference Between A/A and A/B Testing?](https://abfinal.com/blog/what-is-the-difference-between-aa-and-ab-testing): A/A vs A/B testing: an A/A test splits traffic between identical versions to validate your tool, tracking and split. Why about 1 in 20 A/A tests will look significant.
- [What Is the Difference Between A/B Testing and Split Testing?](https://abfinal.com/blog/what-is-the-difference-between-ab-testing-and-split-testing): A/B testing and split testing usually mean the same thing. When there is a difference, split testing refers to split URL tests that redirect visitors to a separate page.
- [What Is the Principle of A/B Testing?](https://abfinal.com/blog/what-is-the-principle-of-ab-testing): The principle behind A/B testing is the randomized controlled experiment. Here's why randomization works and the four rules that keep an online test trustworthy.
- [What Is the Significance Test for A/B Testing?](https://abfinal.com/blog/what-is-the-significance-test-for-a-b-testing): The standard significance test for A/B tests on conversion rate is the two-proportion z-test, equivalent to a 2x2 chi-square test. How it works, with a worked example.
- [When Should You Use A/B Testing?](https://abfinal.com/blog/when-to-use-ab-testing): When to use A/B testing: for uncertain, consequential changes you have the traffic to measure. When not to: bug fixes, obvious improvements, legal requirements.
- [Which Statistical Test Should You Use for an A/B Test?](https://abfinal.com/blog/which-test-to-use-for-ab-testing): Which statistical test to use for an A/B test: z-test or chi-square for conversion, Fisher's exact for small counts, Welch's t-test or bootstrap for revenue.
- [Why Do People Use A/B Testing?](https://abfinal.com/blog/why-do-people-use-ab-testing): Why companies use A/B testing: expert guesses are often wrong, before-and-after comparisons mislead, and a test settles arguments while limiting risk.

## About

- [The ABFinal Blog](https://abfinal.com/blog): Articles on A/B testing: the basics, statistics and analysis, running tests well, and Shopify conversion optimization. Plain language, checked numbers, no fluff.
- [What ABFinal Costs (Nothing) and What You Get](https://abfinal.com/price-contents): ABFinal is free: every A/B testing calculator and guide, with no account, trial or paid plan. Here's what's included, what isn't, and how the site pays its way.
- [Partners and Integrations](https://abfinal.com/partners): ABFinal has no paid partners, affiliates or sponsors. How the free calculators fit alongside testing platforms, analytics and Shopify.
- [About ABFinal](https://abfinal.com/about): ABFinal is an independent, free toolkit of A/B testing calculators and guides. Who it's for, how it's written and checked, and how it relates to this domain's past.
- [Contact ABFinal](https://abfinal.com/contact): How to contact ABFinal: email for corrections, bug reports and suggestions about the A/B testing calculators and guides. No support for the former Shopify app.
- [Privacy Policy](https://abfinal.com/privacy-policy): ABFinal's privacy policy: calculators run in your browser, the site sets no cookies and runs no analytics or ads, and we only receive email you choose to send.
- [Terms of Service](https://abfinal.com/terms-of-service): Terms of service for ABFinal's free A/B testing calculators and guides: free use, no warranty, statistical estimates rather than advice, and how content may be used.