Tournament Bracket Generator (Single Elimination)
Random
Given a list of participants, this tool builds the standard single-elimination bracket used in nearly every cup, knockout tournament, and esports playoff. The number of slots is rounded up to the next power of two (4, 8, 16, 32, 64) and the difference is filled with BYE markers placed on the seeds that should auto-advance — so a 5-person bracket fills 3 BYE slots at the bottom seeds, and the top three seeds auto-advance into the semis. Seeds are arranged in the canonical 1-vs-N, 2-vs-N-1 split: in an 8-bracket the slot order is 1, 8, 4, 5, 2, 7, 3, 6, which guarantees the top two seeds can only meet in the final, the top four only in the semis, and so on. You can seed three ways: as-entered (input order is seed order), alphabetical (sorted ascending by locale), or random (deterministic shuffle seeded by a number you can reseed). The visual bracket shows every round (Final / Semifinal / Quarterfinal / R16 / R32 / R64) with a trophy on the final, and BYE matches auto-resolve so the next round shows the auto-advancer instead of a blank slot. Markdown export gives you a copy-pasteable text bracket for Slack/Discord/issue comments.
About bracket seeding
Bracket slots are arranged so the top seeds can only meet in the later rounds. The algorithm is recursive: for size n, take the seeds for size n/2 and replace each seed s with (s, n+1-s). So size 4 → [1,4,2,3], size 8 → [1,8,4,5,2,7,3,6], size 16 → [1,16,8,9,4,13,5,12,2,15,7,10,3,14,6,11]. BYE markers go on the bottom seeds so top seeds get the auto-advance. Random seeding uses mulberry32 keyed by a deterministic number — reload won't reshuffle, only the Reseed button will. Everything runs client-side; no participant data ever leaves your browser.
How to use
- Paste participants — one per line, or comma-separated. Duplicates are removed.
- Pick a seeding mode. 'As entered' is best when you already have a ranking; 'Alphabetical' is neutral; 'Random' shuffles deterministically and gives a reseed button if you want a different draw.
- Read off the bracket from left to right. Round 1 is the first column; the trophy marks the final.
- BYE rounds are shown in italic — the non-BYE participant automatically appears in the next column.
- Click 'Copy Markdown' to grab a text bracket suitable for chat, issues, or a tournament wiki.
Frequently asked questions
- How does seed placement work?
- The 'standard bracket' guarantees that the top two seeds can only meet in the final, the top four only in the semis, and so on. For an 8-bracket the slot order is [1, 8, 4, 5, 2, 7, 3, 6]: 1 vs 8 and 4 vs 5 in the top half (winners meet in one semi); 2 vs 7 and 3 vs 6 in the bottom half (winners in the other semi). Larger powers of two follow the same recursive rule.
- Where do the BYEs land?
- BYE markers fill the bottom seeds. For 5 participants in an 8-bracket, BYEs go to seeds 6, 7, 8 — which means in the slot order [1, 8, 4, 5, 2, 7, 3, 6], slots 2, 6, 8 are BYEs. So the matches are 1 vs BYE, 4 vs 5, 2 vs BYE, 3 vs BYE — three top seeds advance directly to the semis. This is what every real tournament does (and yes, it is unbalanced toward the top, which is what seeding is supposed to do).
- Can I do double elimination?
- Not yet — this is single-elimination only. Double elimination needs a losers bracket whose structure depends on the exact path each loser took out of the winners bracket, which roughly doubles the visual complexity. For round-robin (everyone plays everyone), see the Round Robin Scheduler tool.
- Why does my 'random' bracket stay the same on reload?
- Random seeding uses a deterministic PRNG (mulberry32) keyed by a numeric seed stored in localStorage. That way reload doesn't shuffle behind your back — handy if you've already announced the draw. Hit the 'Reseed' button to generate a new shuffle.
- How many participants does this support?
- Up to 64 (which fits a 6-round bracket and renders cleanly). Beyond that the visual gets unwieldy in any tool. Big tournaments usually run group stage first and only bracket the top N qualifiers.
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