Download Time Calculator

This calculator works out how long a file takes to move over a given connection, and how fast a connection has to be to finish one by a deadline. File sizes can be entered in either the 1000 based units a drive maker uses or the 1024 based ones your operating system reports, and speeds in megabits or megabytes per second, because mixing those two up is what makes a connection look broken. An overhead percentage takes off what headers, retransmissions and packet gaps never deliver, and the result shows the ideal time alongside it. What it cannot see is a throttled server, a slow disk or a shared line, all of which cost more than the arithmetic does.

Calculator Type

File Size Unit

Speed Unit

Mbps is megabits, MB/s is megabytes. An internet plan is quoted in the first and a download window usually reports the second.

File size, connection speed, and what the connection loses to overhead.

File Size (GB) *

Connection Speed (Mbps) *

Protocol Overhead and Losses (%)

What the payload never gets. Headers and retransmissions cost roughly 3 to 8% on a clean wired link, more on wifi or a busy line. Leave it at zero for the theoretical best case.

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File Size Unit

Time Unit

The other direction: the file has to be there by a deadline, so how fast does the line have to be.

File Size (GB) *

Time Available (h) *

Protocol Overhead and Losses (%)

What the payload never gets. Headers and retransmissions cost roughly 3 to 8% on a clean wired link, more on wifi or a busy line. Leave it at zero for the theoretical best case.

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