A/B Testing Screen Resolution Calculator
Estimate how much traffic and time you need to run an A/B test for visitors using a specific screen resolution.
Overview
Use this A/B Testing Screen Resolution Calculator to estimate the traffic available from a chosen resolution segment and the approximate time needed to expose each variation to enough visitors. Add your daily traffic, the segment's share of traffic, number of variations, and visitor target per variation.
How it works
The calculator multiplies total daily visitors by the selected resolution segment's traffic share to estimate daily segment traffic. It divides that traffic equally across the variations, then calculates how many days are needed for every variation to reach the target visitor count. It also estimates conversion events by applying the expected conversion rate to the target visitors per variation. This is a traffic allocation estimate rather than a full statistical sample-size calculation.
How to use this calculator
- 1Enter the screen resolution or viewport segment you want to test.
- 2Add your average daily eligible visitor count.
- 3Enter the percentage of visitors in that resolution segment.
- 4Choose the number of variations, including the control.
- 5Set a target number of visitors for each variation.
- 6Review the estimated test duration and expected conversion events.
Example Calculation
Screen resolution to test
1920 × 1080
Total daily visitors
10000
Resolution traffic share
18%
Number of variations
2
Target visitors per variation
1000
Expected conversion rate
5%
Estimated test duration
2 days
With 10,000 daily visitors and 18% of traffic using 1920 × 1080, the segment supplies about 1,800 visitors per day. Split between two variations, each gets about 900 visitors daily, so a target of 1,000 visitors per variation takes about 2 days. At a 5% conversion rate, each variation would be expected to produce about 50 conversions.
Frequently asked questions
What does an A/B testing screen resolution calculator estimate?
It estimates how much traffic a selected screen-resolution segment receives, how that traffic is divided between variations, and how long it may take to reach a visitor target.
Should I use screen resolution or viewport size for an A/B test?
Use the segmentation dimension available in your analytics and experimentation platform. Viewport size is often more useful for responsive layout decisions, while reported screen resolution can still help identify broad device segments.
Why is my estimated test duration so long for one resolution?
A specific resolution may represent only a small share of total traffic. Splitting that traffic among multiple variations further reduces the number of visitors each variation receives per day.
How many visitors per variation do I need?
The right target depends on baseline conversion rate, the smallest effect you want to detect, confidence requirements, and test design. Use a statistical sample-size calculation to set this target.
Does this calculator determine statistical significance?
No. It estimates traffic and timing only. Statistical significance also depends on conversion performance, sample-size methodology, and how the experiment is run.
Should traffic be split equally between variations?
Equal allocation is a common default because it gives each variation similar exposure. Uneven allocation changes the traffic each variation receives and may require a different test plan.
Explore Related Calculators
Assumptions and warnings
Assumptions
- Traffic from the selected screen-resolution segment remains broadly consistent during the test.
- Visitors are split evenly between all listed variations.
- The target visitors per variation is chosen separately based on your test's statistical requirements.
- The calculation treats each eligible visitor as one observation and does not account for repeat visitors or exclusions.
- Screen-resolution reporting may differ from browser viewport size, device type, and pixel density.
Warnings
- This calculator is a traffic-planning estimate, not a statistical significance or business-decision tool.
- Low conversion volumes can require a larger sample than the visitor target shown here.
- Avoid ending a test solely because the estimated duration has elapsed; review experiment quality and statistical requirements first.