Knockout tournaments: the bracket format

Players are paired, winners advance, losers leave. The field halves each round, so the number of rounds is fixed by the size of the draw.

Note the last column: half the field plays exactly one game. In a sixteen-player knockout, eight people travel to the venue, play once and go home. That is the defining property of the format, and everything else about using it follows from it.

At serious events each «game» is actually a mini-match of two, so both players get White once. At amateur level a single game is normal - and the colour advantage is then real.

Without seeding, the two strongest players can meet in round one and the final is between two average ones. Seeding places the favourites at opposite ends of the bracket.

• Order by rating or by known strength. Any consistent order is better than none.
• First plays last, second plays second-last. The standard pattern, applied recursively down the bracket.
• The top two can only meet in the final. That is precisely what seeding is for.
• Publish the bracket before it starts. A bracket drawn after people arrive invites the suspicion that it was arranged.

At a club event where nobody has a rating, seed by whatever you know - previous results, the club table, or an open draw made in front of everyone. The last option is weakest for fairness and strongest for trust.

Almost always. Thirteen people turn up and the bracket needs sixteen - the difference is handled with byes in the first round.

• Round up to the next power of two. Thirteen players use a sixteen-player bracket with three first-round byes.
• Byes go to the top seeds. The strongest players skip round one - standard practice, and it also protects the bracket from an early upset removing all the favourites.
• Alternatively, run a qualifying round. The lowest seeds play off for the remaining places, which keeps everybody playing at least once.
• Never improvise mid-event. Decide the method before the draw and publish it.

The qualifying-round version is the better one for an amateur event: it avoids the situation where the people who travelled furthest get to watch the first round - about byes.

A bracket needs a winner in every pair, so a drawn game cannot simply stand. The escalation is standard:

1. 1Two rapid games, one with each colour
2. 2Two blitz games if still level
3. 3Two more with a shorter control
4. 4Armageddon: White has more time, a draw counts as a win for Black

A club event does not need four stages: two blitz games and then armageddon is enough. What matters is that the sequence and the armageddon time odds are in the regulations, not decided while two people stand at the board contesting a trophy - play-offs and armageddon.

The standard fix for the third problem is a consolation event: losers drop into a parallel bracket or a short Swiss and keep playing. It doubles the value of the evening for the people most likely never to return otherwise.

• A show event with spectators. A festival stage, a corporate final, anything with an audience - the bracket is legible to non-players.
• The finale of a longer event. A Swiss decides the top four, and the knockout decides the winner in front of everybody.
• A blitz evening. With five-minute games a single loss costs little, and the whole bracket runs in two hours.
• A team competition. Company against company, where matches rather than individuals advance - industry events.
• Not a regular club evening. People come to play, and a format where half of them play once does not survive repetition - what to use instead.