Why is BitTorrent ETA go up?

[MatthewKoolKid]

Ok so I have a torrent that said 3 weeks remaining, then it skyrockets to 5 weeks, when the progress doesn't budge.

 

[Yevgeniy]

To answer this question i have to explain how bit torrent works. The .torrent file you downloaded and opened is like a map. It tells your computer where to find small peices of the file you are downloading, and then your computer puts the peices together like a jigsaw puzzle. The thing is you are downloading these peices from many many many different people. People just like you, lets call them peers. These peers might log off, close bit torrent, stop letting you download, have a power outage etc. Some people have fast connections, some people slow.

When you are downloading for a large ammoutn of people, say two thousand, thats not an issue. Some people log of, some people log on. But when you are only downloading from only say 10 or 20, one person is quite a noticeable change to your download speed. So when bit torrent tells you it will take 3 hours to complete the download, all it has to work with is the current download speed. It cant predict that your fastest peer will disconnect for one reason or another, and when he does your new download speed is much slower and therefore the ETA jumps up.

So when you are downloading a torrent, look at the number of seeders and leechers. Seeders are peers who have the entire file downloaded, and are just letting other people take pieces from it. Leechers are people who don't have the entire file, and are collecting pieces. Files with more seeders then leechers will download much faster. But files with more peers in general will download even faster yet. Though you cant download faster then your own connection will let you!