The formula
Monthly Bandwidth = Visitors × Pages Per Visit × Average Page Weight × (1 + Safety Buffer) Example: 10,000 visitors × 3 pages × 2.5MB × 1.20 = 90GB "Bandwidth" in a hosting context almost always means total monthly data transfer, not connection speed — how much data your server sends out to every visitor's browser over a billing period, added up. It scales directly with three things: how many people visit, how many pages each of them loads per visit, and how heavy each page is once every image, script, and font is counted.
How heavy is a typical web page?
This is the number most bandwidth estimates get wrong by guessing. HTTP Archive's Web Almanac tracks this directly by crawling millions of real sites, and as of its 2025/2026 edition, the median mobile page weighs about 2.5MB once every resource is counted — roughly three times what it weighed a decade earlier. The presets in the calculator above are based directly on that data's percentile breakdown:
| Percentile | Page Weight | Typical Site |
|---|---|---|
| P25 | ~1.0 MB | Lean, text-focused sites |
| P50 (median) | ~2.5 MB | The current web average |
| P75 | ~5.0 MB | Image galleries, product pages |
| P90 | ~8.1 MB | Video, heavy JavaScript bundles |
If you don't know your own site's actual weight, running it through a page-speed testing tool (Chrome DevTools' Network tab, PageSpeed Insights, or similar) will give you an exact number to use instead of a preset.
Why the safety buffer matters
Traffic doesn't arrive evenly across a month. A single viral post, a marketing campaign, or a seasonal spike can push a normal month's traffic well above its average, and most hosting bandwidth caps are hard limits per billing period, not soft averages. A 20–50% buffer on top of the raw calculation is common planning guidance precisely to absorb that variance without getting caught out by an overage fee or a throttled connection right when traffic is highest.
Frequently asked questions
How much bandwidth does a website need?
It depends on your traffic and page weight: multiply monthly visitors by pages per visit by average page size. A site with 10,000 monthly visitors, 3 pages per visit, and a typical 2.5MB page weight needs about 75GB of raw monthly transfer, or about 90GB with a 20% safety buffer.
What is the average web page size?
About 2.5MB, per HTTP Archive's Web Almanac, which measures this directly by crawling millions of live websites. That figure has roughly tripled over the past decade as sites have added more images, scripts, and fonts.
How much safety buffer should I add to my bandwidth estimate?
20–50% is common guidance, to absorb traffic spikes and growth over a billing period without hitting a hard cap. Sites with unpredictable traffic (news, viral content, seasonal sales) should lean toward the higher end.
Is hosting bandwidth the same as network bandwidth?
No. Hosting companies often use "bandwidth" to mean total monthly data transfer, measured in GB or TB. This is how much data your website sends to visitors over a billing period.
Network bandwidth refers to the connection speed available to transfer data, measured in Mbps or Gbps.
This calculator estimates monthly data transfer (GB/TB), not network connection speed (Mbps/Gbps).
References & Sources
- Page weight percentiles: HTTP Archive Web Almanac 2025 — Page Weight, based on crawling millions of live websites.