A/B testing is a way to find out what actually works rather than what feels right to you. The difference is large — and a big surprise to many advertisers.
In brief
- Test one variable at a time.
- You need statistical significance (usually 100+ conversions per version).
- Let the test run for at least 1–2 weeks.
- 90 % of tests produce no significant difference — that is normal.
What to test in Meta advertising
- Creative: image versus image, video versus still
- Headline: benefit-focused versus problem-focused
- CTA — “Buy now” versus “See more”
- Audience: interests A versus B
What to test on a landing page

- Headline: the main message
- Image — the hero visual
- CTA button: wording, colour, position
- Form length: 3 versus 5 fields
Statistical significance
A test result is significant when the confidence level is above 95 %. In practice that means at least 100 conversions per version.
Under 30 conversions per version means you genuinely do not know what works. Do not draw conclusions.
The most common mistakes

- Testing several variables at once — you cannot tell which one mattered
- Stopping too early — a three-day test means nothing
- Declaring a “winner” when the difference is tiny
- Not documenting the tests, so the same test gets run again a month later
Frequently asked questions
How many tests should run at once?
One significant test at a time per page or campaign. More than that splits the traffic.
How long should a test run?
At least a week, preferably 2–4. It depends not only on the number of conversions but on the variation between weekdays and weekends.
What is a good lift in an A/B test?
A 5 % lift is normal, 20 % is rare. If the difference is 100 % or more, check for errors.
Related reading
External sources:
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