How to use the Download Time Calculator
- Enter the file size and choose MB, GB or TB.
- Enter your connection speed and choose Mbps, Gbps or MB/s.
- Set the share of the speed you expect to get, 90% by default.
- Read the download time.
Formula used
Time = file size in megabytes ÷ effective speed in megabytes per second. 1 byte = 8 bits, so 100 Mbps is 12.5 MB/s. This uses decimal units (1 GB = 1,000 MB).
Worked example
Here is the Download Time Calculator worked through with the example values shown above, so you can check each step by hand.
| Inputs | |
|---|---|
| File size | 50 |
| Size unit | Gigabytes (GB) |
| Connection speed | 100 |
| Speed unit | Megabits per second (Mbps) |
| Share of the speed you actually get | 90 % |
| Result | |
| Download time | 1 h 14 min 4 s |
| Seconds | 4,444 |
| Effective speed (MB/s) | 11.25 |
Bits and bytes
Internet plans are sold in megabits per second (Mbps), and files are measured in megabytes (MB) or gigabytes (GB). One byte is 8 bits, so to get megabytes per second you divide the Mbps by 8. A 100 Mbps connection moves at most 12.5 MB per second.
At 90% efficiency the effective rate is 11.25 MB/s. A 50 GB file is 50,000 MB, so it takes about 1 h 14 min 4 s. At the full 100% it would take 1 h 6 min 40 s.
More examples
A 700 MB file on a 20 Mbps connection takes 5 min 11 s. A 5 GB file on a 1 Gbps line takes 44 s, even with the full gigabit available, because the 90% default and the byte conversion both apply.
The same arithmetic works for uploads. Home connections often have much slower upload speeds than download speeds, so enter your upload speed when sending files.
Why real speeds are lower
The speed on your plan is a maximum. Wi-Fi signal, other devices on the network, the distance to the server, the server’s own limits, protocol overhead and congestion all reduce it. That is why the calculator offers an efficiency setting: 90% is a reasonable guess, and you can lower it if your downloads are usually slower.
A speed test taken at the same time gives the best figure to enter.
Units used here
The calculator uses decimal units, where 1 GB is 1,000 MB, as storage makers and most download sites do. Some operating systems use 1,024 instead and show slightly different file sizes, which changes the time by about 2% to 7%.
For repeating tasks like backups, check the time against your actual transfer rate rather than the plan figure.
Frequently asked questions
What is the difference between Mbps and MB/s?
Mbps is megabits per second. MB/s is megabytes per second. Divide Mbps by 8 for MB/s.
Why is my download slower than my plan?
Wi-Fi, congestion, server limits and overhead all reduce it.
Can I use it for uploads?
Yes, enter your upload speed.
What efficiency should I use?
About 90% for a good wired connection. Lower it for weak Wi-Fi or busy times.
Does it include resuming or pauses?
No, it assumes a steady transfer.
Why 1 GB = 1,000 MB?
That is the decimal convention used by most storage and download sites.
This calculator gives estimates for information only. Actual figures from a bank, employer, tax authority or doctor may differ. It is not financial, tax, legal or medical advice.