The short version
| Single elimination | Double elimination | |
|---|---|---|
| You're out after | One loss | Two losses |
| Matches | n − 1 | 2n − 2, or 2n − 1 with a reset |
| Rounds, 16 entrants | 4 | 4 in the winners' bracket, 6 in the losers' bracket, then the grand final |
| Matches, 16 entrants | 15 | 30 or 31 |
| Fairness | One bad match ends your day | A strong player who slips once can still win |
| Ranks below first | Roughly: ties at 3rd, 5th, 9th… | Better: more places are decided by play |
| Easy to follow | Very | Harder: two brackets, and a final that may be played twice |
The match counts follow from a simple rule. In single elimination every match knocks out one player, and everyone but the champion is knocked out once, so there are n − 1 matches. In double elimination everyone but the champion loses twice, which is 2n − 2 losses, plus one more if the champion lost once along the way and a reset was played.
How single elimination works
Players are seeded into a bracket whose size is the next power of two: 8, 16, 32. If you have 12 players in a 16-slot bracket, four slots are byes, and the top seeds get them. Seed 1 meets the lowest seed in the first round, so the strongest players shouldn't meet until late. Each round halves the field, and the number of rounds is log2 of the bracket size: 3 for 8 players, 4 for 16, 5 for 32.
Its strengths are speed and clarity. Everyone understands it, it fits a schedule, and the final is a real final. Its weakness is that a seeding accident or one off match sends a strong player home early, and everyone knocked out in the same round shares a place.
How double elimination works
Double elimination runs two brackets. The winners' bracket is a normal single-elimination bracket. When you lose there, you drop into the losers' bracket instead of going home. Lose in the losers' bracket and you're out.
- The losers' bracket is longer. It alternates two kinds of rounds: rounds where its own survivors play each other, and rounds where they meet players just dropping down from the winners' bracket. With a winners' bracket of k rounds, the losers' bracket has 2(k − 1) rounds.
- Good brackets avoid instant rematches. Players dropping down are placed so two people who just met don't meet again straight away.
- The grand final is between the winners' bracket champion, who hasn't lost, and the losers' bracket champion, who has lost once.
The grand final reset
Because the winners' side player hasn't lost yet, a single grand final would knock them out after one loss, which breaks the rule of the format. The usual fix is a reset: if the losers' side player wins the first grand final, a second one is played. Toornament's double finals setting describes the options most tools offer: no grand final at all, a single grand final, or a double final where, if the lower bracket winner wins, "the Grand Finals is reset, and a second match is played".
A reset is fairer but harder to schedule, since you don't know until the first final ends whether there'll be another match. If your venue closes at a fixed time, decide in advance and say so in the rules.
When to use which
| Situation | Use |
|---|---|
| Short on time, many players, a casual event | Single elimination |
| The result matters: prizes, qualification, rankings | Double elimination |
| Everyone should play several games, whatever happens | Swiss, or round robin groups |
| Few players (3 to 8) with time to spare | Round robin: everyone plays everyone |
| Large field, one day, a clear winner | Swiss rounds, then a single-elimination top 8 |
| Judges score entries rather than head-to-head play | Judged rounds |
What about round robin and Swiss?
Elimination formats send most players home early, which is fine for a competition and bad for a community event where people came to play. Two alternatives keep everyone in:
- Round robin: everyone plays everyone once. With n players it takes n − 1 rounds (n rounds if n is odd, with one sitting out each round). It's the fairest format, and it gets long quickly: 8 players is 7 rounds and 28 matches. For bigger fields, split players into groups and send the best of each group to a playoff.
- Swiss: everyone plays every round against someone on the same score, for a fixed number of rounds. It ranks a big field in far fewer rounds than a round robin. See how many rounds a Swiss tournament needs.
Seeding
Seeding decides who meets whom early, and in elimination formats that matters a lot. Seed by rating or past results if you have them, by hand if you know the field, and at random if you don't. Publish the seeding method in advance. With byes, the top seeds get them.
Doing this in Programmable Talk
Tournaments run as part of the event: people or teams register through the event page, with optional check-in before the start. Choose single elimination, double elimination with or without a grand final reset, round robin in groups with playoffs, Swiss, or judged rounds. Brackets are the next power of two, with byes to the top seeds; seeding is random, by a rating question on the sign-up form, or by hand. Matches can be best of any number per round, both sides can report a result from their own pages, and matching reports confirm it, and a correction that would change later matches asks before clearing them. The bracket and standings show on the event's public pages. See tournaments, or draw one with the bracket maker.