Bandwidth calculator
How long a download or upload takes at a given internet speed, or the speed you need.
About this calculator
This bandwidth calculator works out how long a download or upload takes, from the file size and your connection speed in Mbit/s.
It can also find the speed you need to move a file within a set time, and shows the time at other common speeds.
How it works
Time = file size in bits ÷ speed in bits per second. A 1 GB file is 8,000 megabits, so it takes 80 seconds at 100 Mbit/s before overhead. kB, MB and GB are powers of 1,000; KiB, MiB and GiB are powers of 1,024.
Last reviewed:
Worked example
- Work out: Download time
- File size: 4.7
- Size unit: GB
- Connection speed: 100
- Speed unit: Mbit/s
- Network overhead: 10%
Download time: 6 min 58 s
Common questions
How long does it take to download 1 GB?
At 100 Mbit/s, about 80 seconds without overhead, or a little under 1.5 minutes in practice. At 10 Mbit/s, about 13 to 15 minutes.
What is the difference between Mbps and MB/s?
Mbps is megabits per second and MB/s is megabytes per second. There are 8 bits in a byte, so 100 Mbps is 12.5 MB/s.
Why is my download slower than my plan's speed?
Network overhead, Wi-Fi signal, busy servers and other devices on your connection all take a share of the bandwidth.
Sources and further reading
The story behind it
Where the idea came from: In 1998 the International Electrotechnical Commission introduced the binary prefixes kibi, mebi and gibi, so that 1 KiB is 1,024 bytes while 1 kB is 1,000.
That is why a 1 TB drive can show as about 931 GB: some operating systems count in powers of 1,024 but still label the result GB.
Why you can trust this calculator
- It runs in your browser. Nothing you type into it is sent anywhere.
- The method is explained on this page, so you can check it yourself.
- Free to use, with no sign-up.
- Results are estimates, so please double-check anything important.
- Spotted a mistake? Tell us and we'll look into it.
After 15 years as a mathematics educator, I built CalculStore to give students, teachers, professionals and anyone working with numbers simple, reliable tools.
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