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A/B Test Significance Calculator — Free Online Tool

Is your A/B test result statistically significant?

Calculate statistical significance of A/B tests. P-value, confidence intervals, required sample size. For marketers and product teams.

🅰️ Control (A)

🅱️ Variant (B)

A conversion rate
0.00%
B conversion rate
0.00%
Uplift (relative)
0%
P-value
—
Enter numbers to see verdict
📚
Learn more

Free A/B test significance calculator — z-test for conversions

Calculate if your A/B test result is statistically significant. Two-proportion z-test with pooled variance. See p-value, confidence intervals, and clear verdict.

How to use this tool

  1. 1

    Enter visitors + conversions

    For both control (A) and variant (B): how many visitors and how many converted.

  2. 2

    Check significance

    See conversion rates, uplift %, p-value, confidence interval, statistical significance.

  3. 3

    Interpret result

    p < 0.05 = statistically significant. 95%+ confidence means the result isn't random noise.

Interpretation guide

  • p < 0.01: very strong evidence against null (99%+ confidence)
  • p < 0.05: standard "significant" threshold (95% confidence)
  • p < 0.10: weak evidence — don\'t call it significant
  • p ≥ 0.10: no significant difference detected

Frequently Asked Questions

What is statistical significance?
The probability that your observed difference is NOT random chance. p < 0.05 = less than 5% chance the difference is random — typically the threshold to consider a test "significant".
What sample size do I need?
Depends on your baseline conversion rate + minimum detectable effect. Rough rule: 1,000-10,000 per variant for typical web A/B tests. Low conversion rates (1%) need more samples; high rates (20%) need fewer.
What if my test is "not significant"?
Three options: (1) Run longer until sample size is adequate — but don't peek and stop early. (2) Accept the null hypothesis — the variants perform equally. (3) Bigger change next time — tiny differences need enormous samples to detect.
Z-test vs t-test vs chi-square?
For proportions (conversion rates), z-test with pooled variance is standard and what we use. For continuous metrics (revenue per visitor), t-test is more appropriate. This tool focuses on conversion-rate tests.
What's confidence interval?
The range where the true difference likely falls. "B is 15% better (CI: 8% to 22%)" means the real uplift is probably between 8-22% — we just don't know exactly where.

Key Takeaways

  • A/B Test Significance Calculator is a free, browser-based calculator tool — is your a/b test result statistically significant?.
  • No signup, no downloads, no file uploads — your data stays on your device.
  • Works on desktop, tablet, and mobile. Install as a PWA for offline access.

How to Use A/B Test Significance Calculator

  1. Open the tool: Launch A/B Test Significance Calculator on Toololis — no account or download needed.
  2. Enter your data: Paste text, enter values, or select a file directly in your browser.
  3. Get instant results: Everything is processed locally — results appear immediately.
  4. Copy or download: Save your output or share it. Bookmark for quick access next time.

A/B Test Significance Calculator — Quick Facts

Price
Free — no limits, no watermarks, no paywalls
Privacy
100% browser-based — no data is sent to any server
Platform
Any modern browser on desktop, tablet, or mobile
Category
Calculator Tools on Toololis
Offline
Works offline after first visit (Progressive Web App)
FeatureDetails
ToolA/B Test Significance Calculator
CategoryCalculator
Signup RequiredNo
File UploadNone — processed in browser
Mobile SupportFully responsive
CostFree forever

Why Use A/B Test Significance Calculator?

You should try A/B Test Significance Calculator for a quick, private way to is your a/b test result statistically significant?. All processing happens in your browser. Your files and data never leave your device. According to web.dev, client-side processing is the gold standard for privacy.

On the other hand, dedicated APIs or desktop tools suit batch processing better. They also handle server-side automation. For everyday tasks, browser tools offer the best speed, privacy, and convenience.

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100% Privacy. This tool runs entirely in your browser. Your data is never uploaded to any server.