A/B Testing Screen Resolution Monthly Calculator Examples
Worked scenarios showing how resolution traffic share, conversion rate, and effect size change an A/B test's required sample and duration.
These examples show why the available traffic for one screen resolution can be much lower than total website traffic. They use an even control-versus-variant split and two-proportion sample-size estimates.
High-traffic resolution segment
A site receives 100,000 visitors monthly, and 25% use the selected resolution. The baseline conversion rate is 5%, and the test targets an increase to 6%.
Input Summary
Monthly website visitors
100,000
Resolution traffic share
25%
Baseline conversion rate
5%
Minimum detectable effect
1 percentage point
Confidence and power
95% confidence, 80% power
Calculation Breakdown
- 1Eligible traffic100000 * 0.2525,000 visitors per month
- 2Required sample per groupTwo-proportion sample-size calculation for 5% versus 6%8,149 visitors
- 3Total and duration(8149 * 2) / 250000.65 months
Result Summary
Total and duration
0.65 months
A/B Testing Screen Resolution Monthly Calculator
The test needs about 16,298 eligible visitors and may reach the planned sample in about 0.7 months.
Small resolution segment with the same conversion goal
A site has 100,000 monthly visitors, but only 5% use the selected resolution. The test still compares 5% against 6%.
Input Summary
Monthly website visitors
100,000
Resolution traffic share
5%
Baseline conversion rate
5%
Minimum detectable effect
1 percentage point
Confidence and power
95% confidence, 80% power
Calculation Breakdown
- 1Eligible traffic100000 * 0.055,000 visitors per month
- 2Required sample per groupTwo-proportion sample-size calculation for 5% versus 6%8,149 visitors
- 3Total and duration16298 / 50003.26 months
Result Summary
Total and duration
3.26 months
A/B Testing Screen Resolution Monthly Calculator
The test may take about 3.3 months to collect the same 16,298 eligible visitors.
Smaller effect at a higher baseline rate
A site has 200,000 monthly visitors, 20% are in the selected resolution, and the baseline rate is 10%. The test aims to detect an increase to 10.5%.
Input Summary
Monthly website visitors
200,000
Resolution traffic share
20%
Baseline conversion rate
10%
Minimum detectable effect
0.5 percentage points
Confidence and power
95% confidence, 80% power
Calculation Breakdown
- 1Eligible traffic200000 * 0.2040,000 visitors per month
- 2Target rate10% + 0.5%10.5%
- 3Required sample per groupTwo-proportion sample-size calculation for 10% versus 10.5%57,738 visitors
- 4Estimated duration(57738 * 2) / 400002.89 months
Result Summary
Estimated duration
2.89 months
A/B Testing Screen Resolution Monthly Calculator
The estimated duration is about 2.9 months despite 40,000 eligible monthly visitors.
How to Read Your Results
Eligible monthly visitors are the estimated people using the selected screen resolution, not all site visitors.
Visitors needed per variation applies separately to control and variant under a 50/50 split.
Total visitors needed is the combined eligible sample required across both groups.
Estimated months is a traffic-planning figure; convert a fractional month into calendar timing using actual daily traffic patterns.
A longer estimate can indicate that a broader segment, a larger meaningful effect, or more traffic may be needed for a practical test.
Assumptions & Important Notes
- Examples use a two-sided comparison of two conversion rates.
- All examples assume equal assignment between the control and variant.
- Traffic share and conversion behavior are assumed to remain stable during data collection.
- Minimum detectable effects are absolute percentage-point changes.
Related Examples
Frequently Asked Questions
Can I use this calculator for a mobile resolution segment?
Yes. Enter the estimated share of visitors in that resolution segment and the baseline conversion rate measured for that segment.
Why do two examples with the same conversion rates have different durations?
They have different eligible monthly traffic. The required sample can be the same while the time to collect it differs.
What happens if I choose 90% power instead of 80% power?
The sample requirement increases because the calculation aims for a higher chance of detecting the chosen effect if it exists.
Can a test take less than one month?
Yes. A result below one month means projected eligible traffic can reach the calculated sample within that period, subject to normal traffic variation.
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