How long will that download take?
Connections are sold in megabits and files are measured in megabytes. The factor of eight between them causes most of the confusion.
1.45 × UK average fixed line
100 Mbit/s is faster than 3 of the 8 references on this page.
Reference figures are measurements and are rounded; the unit conversion behind them is exact.
| Reference | Size | Yours ÷ theirs | Note |
|---|---|---|---|
| dial-up modem | 0.056 Mbit/s | 1,786× | 56 kbit/s |
| basic broadband | 10 Mbit/s | 10× | |
| UK average fixed line | 69 Mbit/s | 1.45× | |
| 5G in practice | 150 Mbit/s | 0.667× | |
| fast fibre | 500 Mbit/s | 0.2× | |
| Wi-Fi 6 in practice | 600 Mbit/s | 0.167× | |
| gigabit fibre | 1,000 Mbit/s | 0.1× | |
| 10 gigabit fibre | 10,000 Mbit/s | 1/100 |
Worth knowing
- Divide megabits per second by eight to get megabytes per second. A 100 Mbit/s line moves 12.5 MB a second at best.
- A 4K film at 15 GB takes 20 minutes on a 100 Mbit/s line and 2 minutes on gigabit — assuming the far end can keep up, which it usually cannot.
Frequently asked
Why is my download slower than my connection speed?
Because the advertised figure is megabits and your download manager shows megabytes — a factor of eight. Beyond that, the server, protocol overhead and Wi-Fi all take a share.
How fast is fast enough?
25 Mbit/s streams 4K comfortably for one person. Above about 200 Mbit/s, extra speed rarely changes anything a household notices except large downloads.