BitTorrent is without a doubt the best way to share large files online. Bram Cohen, BitTorrent’s inventor recently found out that torrents with more peers are not always quicker.
We have written many articles on how BitTorrent users can speed up their downloads in the past. We have focused on tweaking the client’s options such as the max upload speed and the maximum number of incoming and outgoing connections. Tweaking your client can indeed help with speeding up your downloads but many BitTorrent users are looking for the holy grail that will boost their download speeds to the maximum. Picking the right torrent is one of the most important part and the torrents with the most peers are not always the fastest one.
“Cohen designed BitTorrent to be able to download files from many different sources [...] the more popular a file is, the faster a user will be able to download it, since many people will be downloading it at the same time, and these people will also be uploading the data to other users,”
The more people who download a file the better is the explanation that we hear often but unfortunately it’s not very correct.
Cohen explains the reason: “There’s a classic fallacy because if one person stands up during a concert they get a better view, then if everybody stood up during a concert they’d all get a better view. This is of course is not true – they wind up slightly worse off by all standing, because they all compete with each other for a view.”
How to get the most of BitTorrent and what torrents perform the best and generally give you the fastest download times? The fastest torrents are the one where downloaders (leechers) can tap into the most upload capacity. If you have a swarm (seeders and leechers) with a hundred people in total it will be faster when there are relatively more seeders. That’s because seeders don’t download while their upload capacity is available for the leechers.
Many people think that a torrent with 30 seeders and 70 leechers (30% seeders) will go faster than one with 10 seeders and 90 leechers (10% seeders). But it’s a bit confusing when you compare swarms of different sizes.
Example, a torrent with 500 seeders and 2500 leechers (20% seeders) will be slower than a torrent with 30 seeders and 70 leechers (30% seeders). That’s because the swarm has a smaller percentage of seeders. The percentage of seeders that a swarm consists of is the most important thing to look at, when picking the right torrents to download.
The average upload capacity available to the leechers will be higher if the percentage of the seeders is higher as well. All peers have more download capacity than upload capacity that’s why the fact that leechers also upload themselves is irrelevant. It is important to know that the seeders make the difference.
That’s the main reason why private trackers generally have such great download speeds. They have torrents with 100 seeders and only two or three leechers, since users are required to seed as much as possible.
So the most important part of picking the right torrent is to pick those with the best seeder/leecher ratio or the highest percentage of seeders. Another important part is to seed as much as possible, of course if you don’t need your upload speed for something else.