A/B Testing Screen Resolution Annual Calculator FAQ
Answers to common questions about screen-resolution A/B test traffic, sample size, assumptions, and annual test capacity.
Use these answers to understand what the annual screen-resolution calculator estimates, how its inputs affect results, and why actual experiment requirements may differ from a planning calculation.
General Calculator Questions
Core questions about what the calculator measures and when it is useful.
What does this screen-resolution A/B testing calculator estimate?
It estimates annual testable traffic for a selected screen resolution or group, the approximate visitors needed for one conversion test, and the number of similarly sized tests annual traffic may support.
Why assess traffic by screen resolution?
Different viewport layouts can create different user experiences and conversion behavior. Segment traffic helps determine whether there is enough volume to test or evaluate that experience.
Can I use a resolution group instead of one exact resolution?
Yes. Grouping can be useful when resolutions have comparable layouts and user experiences. The grouping should remain meaningful for the question being tested.
Does the calculator measure test duration?
No. It estimates annual capacity. Duration also depends on how traffic arrives over time, test allocation, and operational constraints.
Inputs and Calculation Method
Questions about traffic, conversion rates, detectable effects, and statistical settings.
What should I enter for annual visitors?
Enter estimated eligible visitors or sessions over a full year. Use a unit consistent with the conversion rate used for the segment.
What is a minimum detectable effect?
It is the smallest relative conversion-rate increase or decrease the test is intended to detect with the selected confidence and power settings.
How is a relative effect converted to an absolute effect?
The baseline decimal conversion rate is multiplied by the relative effect decimal. For example, a 20% relative effect from a 4% baseline is 0.8 percentage points.
Why do confidence and power z-scores affect sample size?
Higher confidence or power settings require stronger evidence, which generally increases the estimated sample requirement.
Does the number of variants include the control?
Yes. Enter every variant that receives traffic, including the existing control experience.
Accuracy and Practical Use
Questions about interpreting estimates and planning around real-world experiment conditions.
Is the required sample size exact?
No. It is an approximate planning estimate based on a simplified conversion-rate comparison. Actual requirements can differ.
Why might actual testing need more traffic?
Uneven allocation, repeat visitors, missing data, multiple comparisons, seasonality, metric definitions, and experiment-quality issues can increase practical needs.
What does zero tests supported annually mean?
It means estimated annual testable traffic is below the estimated total needed for one test at the entered settings. It does not prove that all testing is impossible.
Can I run concurrent tests using the annual capacity result?
The capacity result assumes non-overlapping tests. Concurrent tests may interact or divide traffic, so their planning needs separate consideration.
What is the annual testable visitor result?
It is annual traffic in the selected resolution segment after applying the percentage allocated to testing.
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