Data Transfer Rate Converter
Same value in every unit
| Unit | Value |
|---|
Bits, bytes, and the factor of eight
Internet connections are sold in megabits per second. Files are measured in megabytes. There are eight bits in a byte, so a 100 Mbps connection downloads at about 12.5 MB/s at its theoretical best. Nothing is broken — the two numbers simply measure different things.
The notation gives almost no help. Mbps with a small b is megabits; MB/s
with a capital B is megabytes. One character separates figures that differ eightfold.
What common connections actually deliver
- 50 Mbps — about 6.25 MB/s
- 100 Mbps — about 12.5 MB/s
- 300 Mbps — about 37.5 MB/s
- 1 Gbps — about 125 MB/s
Those are ceilings. Real transfers run at roughly 85 to 90 percent of them on a wired connection, and often far less over wifi.
Decimal or binary
A megabyte is 1,000,000 bytes. A mebibyte is 1,048,576 — the power-of-two version. Networking and storage vendors use the decimal units; many operating systems report the binary ones and call them by the decimal names, which is why a "500 GB" drive shows as 465 GB once formatted. Nothing has been lost; it is being counted differently.
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Frequently Asked Questions
Because it is not slow — those are the same speed. Connection speeds are sold in megabits and download managers show megabytes, and there are eight bits in a byte. 100 Mbps is 12.5 MB/s before any overhead. This single confusion is behind most complaints that a connection is underdelivering.
A lowercase b is a bit, a capital B is a byte. Mbps is megabits per second; MB/s is megabytes per second, eight times larger. It is an unforgiving notation, and it is why the unit list above spells out both.
A megabyte is 1,000,000 bytes; a mebibyte is 1,048,576. Network equipment and drive manufacturers use the decimal ones, operating systems often report the binary ones. Both are on the list because both are in daily use.
Divide the file size by the rate once both are in the same unit. A 4 GB file over a 100 Mbps line is 4000 MB divided by 12.5 MB/s, or about 320 seconds at the theoretical maximum — real transfers are slower.
Protocol overhead, contention with other users, wifi losses and the far server's own limits. Getting 85 to 90 percent of the advertised rate on a wired connection is normal; wifi is often much less.
No. This is arithmetic in your browser.