Download Time Calculator
Bits and bytes differ by eight. That is the whole trap.
Work out Download Time. Bits and bytes differ by eight. That is the whole trap. Shows the working, not just the answer.
Download time
1m 27s
1,000 MB at an effective 92 Mbps
The trap is bits against bytes. Connection speeds are quoted in megabits per second and file sizes in megabytes, a factor of eight apart — so a 1 GB file on a 100 Mbps connection takes 80 seconds, not 10. Protocol overhead removes another 5 to 10% before any real data moves. TCP headers, acknowledgements, retransmissions and encryption all consume capacity, which is why a speed test rarely matches the number on the contract. Latency matters as much as bandwidth for anything interactive. A high-latency satellite link with plenty of bandwidth downloads large files perfectly well and feels dreadful for anything that waits on a round trip.
How the Download Time Calculator works
Download time from file size and connection speed, with protocol overhead and comparisons at other speeds. Speeds are quoted in megabits and files measured in megabytes — a factor of eight that catches almost everyone.
Also known as: how long to download a file · mbps to mb per second · why is my download slower than my speed · time to upload a video
Frequently asked questions
How long does 1 GB take on 100 Mbps?
About 80 seconds with no overhead, and closer to 90 in practice. Not 10 seconds — the file is 8,000 megabits, not 1,000.
Why is my download slower than my connection speed?
Protocol overhead removes 5 to 10% before any real data moves, and the server, the route or your own hardware may be the bottleneck rather than the connection.
What is the difference between Mbps and MB/s?
A factor of eight. 100 Mbps is 12.5 MB/s at best, which is why a download manager showing 11 MB/s on a 100 Mbps line is performing perfectly.
Does latency affect download speed?
For a single large file, barely. For anything made of many small requests it dominates, which is why a high-latency satellite link with plenty of bandwidth feels dreadful to browse on.
Is upload time the same calculation?
Yes, with the upload speed. On asymmetric connections upload is often a fifth or less of download, which is why sending a large file takes so much longer than receiving one.
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