How long will this download take?
The download time is the file size divided by the speed. The only catch is the units. File sizes are counted in bytes, while internet and network speeds are counted in bits per second, and one byte is 8 bits. So before you divide, the file size has to be turned into bits, or the speed into bytes per second. This calculator does that for you and works the same for uploads: enter your upload speed and you get the upload time.
The formula
Example: a 5 GB file is 5,000,000,000 bytes, or 40,000,000,000 bits. At 100 Mbps, which is 100,000,000 bits per second, that takes 400 seconds, or 6 minutes 40 seconds.
Mbps vs MB/s: bits and bytes
A small b means bits, a capital B means bytes. Mbps (or Mb/s) is megabits per second; MB/s is megabytes per second. Because a byte is 8 bits, the same speed is 8 times smaller in MB/s than in Mbps:
- Mbps to MB/s: divide by 8. 100 Mbps is 12.5 MB/s, 1 Gbps is 125 MB/s.
- MB/s to Mbps: multiply by 8. 25 MB/s is 200 Mbps.
The kilo, mega and giga in a data rate are decimal. NIST notes that telecommunications engineers use a megabit per second to mean exactly 1,000,000 bits per second. For any other pair of data rate units, the unit converter has a data rate type with bps, Kbps, Mbps, Gbps, B/s, KB/s, MB/s and GB/s.
Decimal vs binary file sizes
File sizes come in two systems. In the decimal one, 1 KB is 1,000 bytes, 1 MB is 1,000,000 bytes and 1 GB is 1,000,000,000 bytes. In the binary one, each step is 1,024: 1 KiB is 1,024 bytes, 1 MiB is 1,048,576 bytes and 1 GiB is 1,073,741,824 bytes. The binary names kibi, mebi and gibi were approved by the International Electrotechnical Commission (IEC) in 1998, as listed by NIST. A GiB is about 7.4% larger than a GB, so picking the wrong one changes the time by the same share. The data storage converter converts between the two.
Download times at common speeds
Time for 1 GB, 10 GB and 100 GB (decimal) at the full speed, with no overhead:
| Speed | 1 GB | 10 GB | 100 GB |
|---|---|---|---|
| 10 Mbps | 13 min 20 s | 2 h 13 min 20 s | 22 h 13 min 20 s |
| 25 Mbps | 5 min 20 s | 53 min 20 s | 8 h 53 min 20 s |
| 50 Mbps | 2 min 40 s | 26 min 40 s | 4 h 26 min 40 s |
| 100 Mbps | 1 min 20 s | 13 min 20 s | 2 h 13 min 20 s |
| 300 Mbps | 27 s | 4 min 27 s | 44 min 27 s |
| 500 Mbps | 16 s | 2 min 40 s | 26 min 40 s |
| 1 Gbps | 8 s | 1 min 20 s | 13 min 20 s |
When the real download is slower
The calculator gives the time at the speed you enter. Your file may arrive more slowly than that, for example when the server sends it slowly or other devices share your connection. The most honest input is a speed you have measured yourself. If you want a margin, the overhead field takes a percentage off the speed: 10% overhead on 100 Mbps leaves 90 Mbps for the file.
How to use the download time calculator
- 1Choose Download time to get a duration, or Speed needed to get the speed for a deadline.
- 2Type the file size and pick its unit, decimal like GB or binary like GiB. Then enter your speed in Mbps, Gbps or MB/s, or the hours, minutes and seconds you have.
- 3Read the result and the table of the same file at other speeds. Copy it, or copy a link that opens the same numbers.
Frequently asked questions
How do I convert Mbps to MB/s?
Divide by 8. One byte is 8 bits, so 100 Mbps (megabits per second) is 12.5 MB/s (megabytes per second), and 1 Gbps is 125 MB/s. To go from MB/s to Mbps, multiply by 8. The calculator shows both for any speed you enter.
How long does it take to download 1 GB?
At 100 Mbps a 1 GB file takes 80 seconds: 1 GB is 8,000 megabits, and 8,000 ÷ 100 = 80. At 10 Mbps it takes 800 seconds, about 13 minutes 20 seconds, and at 1 Gbps 8 seconds. These are the times at the full speed. If your connection delivers less, enter the speed you actually measure.
What is the difference between GB and GiB?
GB (gigabyte) is decimal: 1,000,000,000 bytes. GiB (gibibyte) is binary: 1,073,741,824 bytes, which is 1,024 × 1,024 × 1,024. A GiB is about 7.4% larger than a GB. If the size you have was counted in steps of 1,024, pick the binary units, even if the program labels them GB.
Does the calculator include overhead?
Only if you ask for it. By default it uses the full speed you enter. If you know your downloads run slower than the speed you typed, for example from a speed test, enter that speed instead, or set an overhead percentage to take that share off the speed.
Can I calculate upload time too?
Yes. The math is the same in both directions. Enter your upload speed instead of your download speed, and the result is the time it takes to upload the file.
What speed do I need to download a file in a set time?
Switch to Speed needed and enter the file size and the time you have. The calculator divides the size in bits by the time in seconds. For example, 5 GB in 10 minutes needs 40,000 megabits in 600 seconds, which is about 66.7 Mbps.