You pay for a 100 Mbps connection, start a big download, and the progress bar says about 11 MB per second. Nothing is broken. The two numbers use different units, and real connections never quite reach the advertised speed.
Bits and bytes
Mbps means megabits per second. MB/s means megabytes per second. A byte is 8 bits, so divide Mbps by 8 to get the most you could see in MB/s. A 100 Mbps connection tops out at 12.5 MB/s.
Estimating a download time
Convert the file size to bits by multiplying by 8, then divide by the connection speed. Then allow for overhead: protocols add their own data, Wi-Fi loses some speed, and the server may be slower than your line. Allowing 10% is a reasonable starting point.
At full speed
5 GB × 8 bits ÷ 100 Mbpsequals6m 40s
Allowing 10% overhead
6m 40s ÷ (1 − 10%)equals7m 24s
At that 10% allowance, your effective speed is 90 Mbps, or 11.25 MB/s, which is about what the progress bar shows.
More examples
- A 50 GB game on a 300 Mbps connection: about 22 minutes at full speed, or 24m 41s with 10% overhead.
- A 2 GB video uploaded at 20 Mbps: 13m 20s at full speed, or 14m 49s with overhead. Upload speeds are often much lower than download speeds on home plans.
Why it may be slower still
- Wi-Fi, especially through walls or far from the router.
- Other devices on the same network streaming or downloading.
- The server you download from limiting each connection.
- Busy evening hours on your provider's network.
Tip: To test your real speed, plug a computer into the router with a cable and run a speed test. If it is close to your plan, the bottleneck is Wi-Fi or the server, not your line.