Split Test Studio — A/B Test Significance Calculator & Sample Size Planner
$14.97
Stop guessing which variant wins. Split Test Studio tells you in one click whether your A/B test result is real or just random noise.
What’s inside:
• One-click significance test — enter visitors & conversions for A/B, get p-value, z-score and confidence level instantly
• Clear verdict banner — “Winner”, “Loser” or “Keep testing”, no statistics degree required
• Sample size planner — know exactly how many visitors you need BEFORE you start the test
• Visual conversion-rate comparison bars — see the gap at a glance
• 100% private — all calculations run locally in your browser, your data never leaves the page
• Built-in presets — try small uplift, big winner and too-early scenarios to learn how it works
Every marketer runs A/B tests. Almost nobody checks whether the result is statistically valid. Split Test Studio fixes that — it’s the significance calculator and sample-size planner I wish I had when I started split-testing landing pages, emails and ads.
WHAT IT DOES
Significance Test — paste in visitors and conversions for Variant A (control) and Variant B (challenger). The tool runs a two-proportion z-test (two-tailed, the industry standard) and returns:
– Conversion rate for each variant
– Relative uplift (with color-coded positive/negative indicator)
– Z-score, p-value and confidence level
– A plain-English verdict: Winner, Loser, or Keep Testing
Sample Size Planner — enter your baseline conversion rate and the smallest lift you care about. Get the exact visitors-per-variant you need at 95% confidence / 80% power, plus a time estimate at your traffic level. No more stopping tests too early.
HOW TO USE IT
1. Download and unzip — open split-test-studio.html in any browser. No install, no account, no internet needed.
2. Go to the Significance Test tab, enter your test numbers, hit Calculate.
3. Read the verdict. Green = ship it. Yellow = keep the test running.
4. Before your NEXT test, use the Sample Size Planner tab to set your target sample size in advance.
WHO IT’S FOR
– Ecommerce sellers split-testing product pages, prices and checkout flows
– Email marketers testing subject lines and CTAs
– Bloggers and affiliates testing headlines, buttons and layouts
– Agencies that need to show clients proof, not gut feeling
WHY IT BEATS FREE ONLINE CALCULATORS
– No ads, no signup, no “premium unlock” — you own the file forever
– Works offline — test data stays on your machine, never uploaded anywhere
– Includes the planner most free calculators hide behind a paywall
– One file, zero dependencies — works in 10 years the same as today
WHAT YOU GET
– split-test-studio.html — the complete tool (single file, ~17KB)
– Lifetime access + free updates
TECHNICAL NOTES
– Methodology: two-proportion z-test (two-tailed), α = 0.05; sample-size formula at 95% confidence / 80% power
– Verified against textbook examples (z = 1.963, p = 0.0496 on the classic 120/1000 vs 150/1000 case)
– 100% client-side JavaScript — no external requests, no tracking
