Mbps vs MB/s — what's the difference?

Your broadband is "100 Mbps" but files download at "12 MB/s". Both are right — they're just measuring in different units. Here's the simple version.

The whole confusion comes down to one word: bit versus byte. A byte is 8 bits. Broadband speeds are quoted in bits, but file sizes and download managers usually count in bytes — so the two numbers look wildly different for the same connection.

The two units

Mbps means megabits per second (note the lowercase "b"). This is how internet providers advertise speed — "500 Mbps full fibre".

MB/s means megabytes per second (uppercase "B"). This is how your computer usually shows a download in progress, because files are measured in megabytes.

The magic number is 8

Because one byte is eight bits, you divide the Mbps figure by 8 to get MB/s:

Advertised speed	Real download speed
50 Mbps	≈ 6.25 MB/s
100 Mbps	≈ 12.5 MB/s
200 Mbps	≈ 25 MB/s
500 Mbps	≈ 62.5 MB/s
1,000 Mbps (1 Gbps)	≈ 125 MB/s

So a 100 Mbps connection downloading a file at "12.5 MB/s" isn't broken or being throttled — that's exactly the speed you're paying for, just shown in bytes.

Why do providers quote Mbps at all?

Partly convention, partly that bigger numbers sound better in adverts ("100 Mbps" reads better than "12.5 MB/s"). Networking has always measured data rates in bits per second, so it's the technically standard unit — even if it's the less intuitive one for everyday use.

A quick real-world example

Say you're downloading a 6 GB game. That's about 6,000 MB (megabytes). On a 100 Mbps line — 12.5 MB/s — that's roughly 6,000 ÷ 12.5 = 480 seconds, or about 8 minutes at full speed. In practice it's a little longer because no connection runs at 100% the whole time.

See both at once

Our speed test lets you switch the display between Mbps and MB/s with one click, so you can see your connection in whichever unit makes sense to you.

→ Run the free Broadband Speed Test