The download speed depends on the ADSL line speed you subscribe. For example:
- Your file is 2GB size.
- Your link speed is 2Mbps.
- You are estimating 80% link speed, to account for the network overhead.
So, goto Google search and type this:
2GB / ( 2Mbps * 0.8)
The result shows it is estimating 2.85 hours to complete the download.
See other examples at http://stuffphilwrites.com/2011/01/long-image/