Bandwidth Calculator
This free bandwidth calculator estimates how much data your website transfers each month and how long a file takes to download or upload at a given connection speed.
Decimal units by default: 1 MB = 1,000,000 bytes. MiB, GiB and TiB are binary (1 MiB = 1,048,576 bytes). Calculated in your browser, nothing is sent to us.
How to estimate your website's bandwidth
Monthly bandwidth is roughly visitors × pages per visit × average page size. 10,000 visitors viewing 3 pages of 2 MB each transfer about 60 GB a month.
We multiply that by a redundancy factor, 1.5 by default, to leave room for traffic spikes, search engine crawlers, other bots and growth. Everything is calculated in your browser.
MB or MiB? Bits or bytes?
Network traffic and disk makers use decimal units: 1 MB is 1,000,000 bytes and 1 GB is 1,000,000,000 bytes. Some operating systems count in binary units, where 1 GiB is 1,073,741,824 bytes, so the same amount of data looks about 7% smaller in GiB.
Connection speeds are measured in bits per second, and files in bytes. One byte is eight bits, so a 100 Mbps connection moves at most 12.5 MB per second, and a little less once protocol overhead is counted.
Average speed versus peaks
The Mbps figure is the average over a 30-day month. Real traffic comes in waves: busy hours, a newsletter going out, a post that takes off. Size your connection for peaks several times the average.
Hosting plans usually meter the monthly amount (GB per month), while the connection speed (Mbps) limits how fast data can flow at any moment. They're related, but not the same thing.
How to use less bandwidth
Page weight is the lever you control. Halve the average page size and you halve the monthly transfer, for the same number of visitors.
Serve images in WebP or AVIF at the size they're shown, turn on gzip or Brotli compression, and let browsers cache static files so returning visitors don't download them again.
Frequently asked questions
How much bandwidth does a small website need?
Often less than people think. 5,000 visitors a month viewing 3 pages of 2 MB each is about 30 GB a month before any safety margin. Put your own numbers into the calculator above.
How long does it take to transfer 1 GB?
About 80 seconds at 100 Mbps and about 8 seconds at 1 Gbps, at full speed. Real transfers take a bit longer because of protocol overhead and the speed of the other side.
What's the difference between bandwidth and data transfer?
Strictly, bandwidth is the speed (Mbps) and data transfer is the amount (GB per month). Hosting plans often say bandwidth for both, so check which one a limit refers to.
Why does my 1 TB drive show 931 GB?
The drive maker counts in decimal (1 TB = 1,000,000,000,000 bytes), while your operating system counts in binary GiB but labels them GB. 10^12 bytes is about 931 GiB.
What redundancy factor should I use?
1.5 is a sensible start. Use 2 or more if your traffic is spiky, you run campaigns, or you expect to grow over the next year.