Download Time Calculator
How long a file takes to download at a connection speed, or the speed you need to download it in time.
Your download
Filled in with example values. Replace them with your own.
Optional
Real downloads often run below the advertised speed (network protocols, Wi-Fi, a busy server). Enter how much slower you expect, in percent.
Results update as you type.
Result
50 GB at 100 Mbps: 1 h 6 min 40 s
Download time
1 h 6 min 40 s
- File size in bits
- 400,000,000,000 bits
- Speed in bytes1 byte = 8 bits
- 100 Mbps · 12.5 MB/s
At other speeds
| Speed | Time |
|---|---|
| 10 Mbps | 11 h 6 min 40 s |
| 50 Mbps | 2 h 13 min 20 s |
| 100 Mbps | 1 h 6 min 40 s |
| 300 Mbps | 22 min 13 s |
| 1 Gbps | 6 min 40 s |
How it’s calculated
Size in bits
50,000,000,000 bytes × 8 = 400,000,000,000 bits
Time
400,000,000,000 ÷ 100,000,000 bit/s = 1 h 6 min 40 s
How the download time calculator works
A file’s size is converted to bits and divided by the connection speed in bits per second. You can also work it the other way round: enter how long you have, and the calculator gives the speed you need.
No slowdown is assumed. If you know your downloads usually run slower than the advertised speed, add an overhead percentage and both directions take it into account.
The formula
Time = Size in bits ÷ (Speed × (1 − Overhead))
Speed needed = Size in bits ÷ Time ÷ (1 − Overhead)
1 byte = 8 bits; 1 Mbps = 1,000,000 bits per second; 1 MB/s = 8 Mbps.
Worked examples
- 50 GB at 100 Mbps: 50 × 10⁹ × 8 = 400 × 10⁹ bits ÷ 100 × 10⁶ = 4,000 seconds, 1 h 6 min 40 s.
- The same file at 1 Gbps takes 400 seconds, 6 min 40 s.
- To download 10 GB in 1 hour you need 80 × 10⁹ bits ÷ 3,600 s = 22.22 Mbps.
Assumptions
- The speed is steady for the whole download, and only the overhead you enter is taken off.
- Speeds use decimal prefixes, as internet providers quote them.
Frequently asked questions
What is the difference between Mbps and MB/s?
Mbps is megabits per second, the unit internet providers use. MB/s is megabytes per second, often shown by download managers. One byte is 8 bits, so 100 Mbps is 12.5 MB/s.
Why is my download slower than the calculator says?
The calculator assumes the full speed you enter. In practice, network protocols, Wi-Fi, other devices on your connection and the server you download from can all slow it down. Turn on “Allow for overhead” and enter a percentage to see the effect.
What overhead should I use?
It varies too much between connections to give one number. The most reliable way is to measure: run a speed test, or note the speed a large download actually reaches, and enter that as the connection speed instead.
Is the file size in GB or GiB?
Both are available. Websites usually give sizes in decimal units (GB), while some operating systems show binary units (GiB) under the name “GB”. A GiB is about 7.4% larger than a GB.