Mbps vs. MB/s: internet speed explained clearly
Understand the difference between megabits and megabytes and why download speeds look lower than an internet plan’s advertised number.
The capital B makes the difference
A lowercase b means bits, while an uppercase B means bytes. Internet providers normally advertise megabits per second because the number is larger. Browsers and download apps often display megabytes per second.
The two measurements describe the same flow of data using different units, much like inches and feet describe the same length.
Examples at common speeds
A 100 Mbps connection has a theoretical maximum of 12.5 MB/s. A 300 Mbps connection equals 37.5 MB/s, and a 1,000 Mbps connection—often called gigabit—equals 125 MB/s.
These are maximum conversions. Real downloads may be slower because of Wi-Fi conditions, network overhead, the remote server, other devices, and the speed of your own hardware.
Why speed tests and downloads show different numbers
Most speed tests report Mbps, matching the internet plan. A game launcher may report MB/s. If a 400 Mbps speed test and a 45 MB/s download appear side by side, they are actually close: 45 MB/s equals 360 Mbps.
Always check the capitalization before deciding that a download is unusually slow.
Related units you may see
The same bit-versus-byte rule applies at every scale. Eight gigabits equal one gigabyte, just as eight megabits equal one megabyte.
- Kbps: kilobits per second
- Mbps: megabits per second
- Gbps: gigabits per second
- KB/s: kilobytes per second
- MB/s: megabytes per second
- GB/s: gigabytes per second
Frequently asked questions
Is 100 Mbps the same as 100 MB/s?
No. 100 Mbps equals a theoretical maximum of 12.5 MB/s.
Why do internet companies use megabits?
Networking has traditionally been measured in bits per second, and the unit provides a consistent way to describe connection capacity.
How many Mbps is 1 MB/s?
One megabyte per second equals eight megabits per second.
Published August 3, 2026 · Reviewed for clarity and source accuracy.