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Transfer time calculator

Enter a file size and a link speed to see how long the transfer takes.

Work out

The share of the link that packet headers use. About 5–10% is typical for TCP/IP. Leave at 0 to ignore it.

Try:

Result

Example: type your own size and speed above.

Time1 min 20 s80 seconds

How it works

Link speeds count bits per second, and file sizes count bytes. A byte is 8 bits, so the time is the size in bits divided by the speed: 1 GB is 8,000,000,000 bits, and at 100 Mbit/s that's 80 seconds.

Real transfers are slower than that. Every packet carries headers (Ethernet, IP and TCP), so some of the link carries no file data. The overhead box takes that share off the speed. Wi-Fi, a busy link, or a slow server at the other end can cost far more.

Watch the units: MB/s is megabytes a second, and Mbit/s is megabits a second, 8 times less. Download tools often show MB/s or MiB/s, while internet plans are sold in Mbit/s. The data unit converter explains MB versus MiB. On long or distant links, the bandwidth-delay product shows whether one TCP connection can use the whole speed.