Single-elimination brackets, explained
Single-elimination is the purest tournament format: lose once and you're out. It's how the college basketball tournament, most esports playoffs, and every office ping-pong ladder works. Here's how to structure one correctly — especially the seeding and bye math people get wrong.
The rules in sixty seconds
Teams are paired for first-round games. Winners advance to play winners; losers are eliminated. Rounds repeat until one team remains — a tournament of N teams takes exactly N−1 games and ⌈log₂N⌉ rounds. That's the whole format; everything else is presentation.
Seeding: why 1 plays 16 (and 2 plays 15)
Brackets are seeded so the best teams meet as late as possible. The standard 'complement' seeding pairs seeds that sum to N+1 in round one (1v16, 8v9, 4v13, 5v12, 2v15, 7v10, 3v14, 6v11), then re-pairs so a chalk path gives 1v8, 4v5 in round two and 1v4 in the semifinal. Our generator implements the textbook order — you never have to think about it.
Unseeded (random draw) brackets are fine for casual events, but if you have any ranking information at all, use it — a random draw that puts your two best players in round one will be remembered forever.
Byes and non-power-of-two fields
Clean brackets need 4, 8, 16, 32, or 64 teams. With any other number, the highest seeds get byes (automatic first-round wins) until the second round is a power of two. A 12-team bracket: seeds 1–4 get byes, seeds 5–12 play round one. A 12-team tournament still takes 11 games — the math always holds.
When NOT to use single-elimination
- Small groups who traveled far — one-and-done means someone plays one game and goes home. Use double-elimination.
- League play over a season — you want round-robin or pick'em, not a bracket.
- Events where a single bad game shouldn't end a run — double-elimination forgives one loss.
FAQ
How many games are in a single-elimination tournament?
Always exactly one fewer than the number of teams: a 16-team bracket has 15 games, a 64-team bracket has 63. Every game eliminates exactly one team until one remains.
How do byes work in a bracket?
When the field isn't a power of two (4, 8, 16, 32, 64), the top seeds receive byes — automatic first-round wins — so that round two starts with a power-of-two field. In a 12-team bracket, seeds 1–4 get byes.
What's the difference between seeded and random brackets?
Seeded brackets place the strongest entrants so they can only meet in later rounds (1v16, 2v15…), which rewards season-long performance. Random-draw brackets ignore rankings — fine for casual play, risky for competitive ones.
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