Download Time Calculator
How long a transfer takes, and the units people keep confusing.
How it works
The confusion is always bits versus bytes. Connections are sold in megabits per second; files are measured in megabytes. There are eight bits in a byte, so a 100 Mbps line moves at most 12.5 MB/s — and the "at most" matters, because TCP, IP and Ethernet headers consume several per cent before any of your data moves.
The second trap is that a "GB" from a drive manufacturer is 1,000,000,000 bytes while a "GB" in your operating system is 1,073,741,824. Both units are offered above.
Common questions
Why is my download slower than my connection speed?
Protocol overhead takes 5-10%, the server may cap per-connection throughput, and the bottleneck is often somewhere other than your own line.