Bandwidth calculator

Hosting plans are sold in gigabytes of transfer a month. Networks are measured in megabits a second. Site owners know neither — they know how many visitors they get and roughly how heavy a page is. This converts between all three.

Enter your traffic and the transfer allowance your plan includes, and the calculator shows the monthly transfer you will use, the average line speed that represents, a peak estimate for the busiest hour, and how many visitors your current allowance actually covers.

The arithmetic, so you can check it

Monthly transfer is pageviews multiplied by the weight of a page, plus overhead. Pageviews are visitors times pages per visit. Overhead covers everything the page weight alone misses: API calls, fonts and images fetched later, retries, TLS handshakes and protocol bytes. Fifteen percent is a reasonable starting point; a media-heavy site is higher.

To convert that into speed, multiply gigabytes by eight to get gigabits, then spread them over the seconds in a month. One terabyte a month is 3.09 Mbps sustained — a useful anchor to carry around.

Average is not what your server has to survive

Traffic is not flat. A site with one audience and one time zone can see its busiest hour run three to five times the daily average, and a launch or a front-page link is far above that. The peak multiplier exists so the number you plan around is the busy hour, not the quiet night.

Transfer allowances are usually monthly totals, so a peak costs you nothing extra until the month's total runs out — but the line speed has to carry the peak, or the site is slow exactly when it is busiest.

The cheapest gigabyte is the one you never send

Before buying more transfer, cut what leaves the server. Compression (gzip or brotli) typically halves HTML, CSS and JavaScript. Modern image formats and correct sizing often cut image bytes by more than half, and images are most of a typical page. Cache headers stop repeat visitors re-downloading anything at all.

A CDN in front of the server moves most of the bytes off your plan entirely. Measure first — put your real average page weight into the field above rather than a guess, because that single number drives the whole answer.

Common questions

Is bandwidth the same as data transfer?

No, though hosts use the words interchangeably. Bandwidth is a rate — how fast the connection is, in Mbps. Transfer is a volume — how many gigabytes move in a month. A plan usually caps the volume and shares the rate.

How much bandwidth does a typical website need?

A small business site with 10,000 visitors a month and 2 MB pages uses roughly 50 GB a month — under 0.2 Mbps sustained. Transfer is rarely the binding constraint until you serve video, large downloads or images at scale.

What counts towards my transfer?

Usually outbound traffic: pages, images, downloads, API responses and backups you push off the server. Inbound is often free or unmetered. Check the plan, because the difference is large for a backup or file server.

What happens if I go over?

It depends on the host. Some bill the overage per gigabyte, some slow the port to a lower speed until the month resets, and some suspend the service. Find out which before you need to know.

Does a CDN reduce my bandwidth bill?

Almost always. The CDN serves cached files from its own network, so only cache misses and uncacheable responses reach your server. For an image-heavy site that can remove most of the monthly transfer.