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A/B Testing File Size (Monthly) Calculator

Estimate how an A/B test changes monthly data transfer when your control and variant pages have different file sizes.

Your Details

Overview

This A/B Testing File Size (Monthly) Calculator estimates how much data your experiment transfers each month. Enter expected visitors, tested-page views per visitor, traffic allocation, and the average file sizes of the control and variant to compare test traffic with an all-control baseline.

How it works

The calculator multiplies monthly visitors by pageviews per visitor to estimate tested-page traffic. It allocates that traffic between the control and variant according to the selected split, then multiplies each group by its respective file size. The combined result is compared with the data that would be transferred if all tested pageviews used the control. A negative bandwidth difference means the experiment is using less data than the all-control baseline.

How to use this calculator

  1. 1Enter the expected number of visitors to the tested page each month.
  2. 2Add the average number of tested-page views per visitor.
  3. 3Set the percentage of traffic assigned to the variant.
  4. 4Enter the average transferred file size for the control and variant pages.
  5. 5Review the monthly transfer difference and percentage change.

Example Calculation

Monthly visitors

100000

Pageviews per visitor

2

Variant traffic share

50%

Control page file size

1500

Variant page file size

1200

Monthly bandwidth difference

-30.00 GB

With 200,000 monthly tested pageviews split evenly, the test transfers 270 GB per month instead of 300 GB for an all-control experience, saving an estimated 30 GB (10%).

Frequently asked questions

What does the monthly bandwidth difference mean?

It is the difference between estimated data transfer during the A/B test and the transfer that would occur if every tested pageview used the control. A negative number indicates lower data transfer.

Should file size include images, scripts, and fonts?

Yes. Use the average total transferred size for the pageview, including assets that are typically downloaded as part of the tested experience.

Why might actual data transfer differ from this estimate?

Caching, repeat visitors, device differences, compression, lazy-loaded content, bot traffic, and changing traffic patterns can all affect actual transferred data.

What traffic share should I enter for a 50/50 A/B test?

Enter 50%. The calculator assigns half of estimated tested pageviews to the variant and the other half to the control.

Can I use this calculator for an A/B test where the variant is larger?

Yes. If the variant file size is larger than the control size, the monthly bandwidth difference will be positive, indicating additional transfer compared with the baseline.

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Assumptions and warnings

Assumptions

  • File sizes represent the average number of kilobytes transferred for each tested pageview.
  • One GB is treated as 1,000,000 KB for bandwidth planning.
  • The traffic split remains consistent throughout the month.
  • All tested pageviews are assumed to load the relevant control or variant assets.
  • Results estimate transferred data only and do not include CDN, hosting, or bandwidth charges.