McGaw LLC

This extension allows you to calculate the statistical significance & conversion rate of your A/B tests.

Free AB test calculator for marketers who run experiments across every channel. Not just websites. Calculate statistical significance for email AB testing, social media AB testing, Google Ads experiments, Facebook ad tests, landing pages, mobile app tests, PPC campaigns, and ad copy testing. If you can split an audience, this calculator works. **What you get:** • AB testing calculator with statistical significance scoring • Multi-variant testing — compare more than two variations at once • Sample size calculator so you know when to call a test • Save test details with names, notes, and dates • Running test history log — every experiment tracked in one place • Restore past results with a single click • CSV export for reporting and team sharing • Works on any marketing experiment, not just website CRO **Why this exists:** Most AB testing tools are locked inside platforms. VWO and Optimizely only calculate tests run on their own software. Google Ads has a built-in calculator that only works for Google Ads. This is a standalone split test calculator. Run it alongside any tool, any platform, any channel. Your email tool doesn't have a significance calculator? Use this. Running a Facebook ad experiment and need to check results? Use this. Testing two subject lines in your CRM? Use this. **Who it's for:** Growth teams, CRO specialists, marketing ops, and anyone running marketing experiments who needs a fast, reliable calculator without logging into another platform. This is a CRO tool built for operators, not a toy demo. **New: Test History & Experiment Tracking** Save every test you run. Name it. Tag it. Add notes. Come back later and restore the exact inputs and results. No more lost spreadsheets. No more "what were the numbers on that test we ran in March?" Export your full test history to CSV. Share it with your team. Build your own experiment library. **Free AB Testing Tracking Sheet** Want a structured framework for logging all your experiments? Download our free AB Testing Tracking Sheet Template — built by the McGaw.io team to help you run a disciplined testing program. Get it here: mcgaw.io/resources/ab-testing-tracking-sheet-template/ **About McGaw.io** McGaw.io helps growth teams build and optimize their MarTech stack, analytics, and experimentation programs. We've run thousands of experiments across hundreds of companies. This extension is how we calculate results ourselves. Questions or feedback? Visit us at mcgaw.io