For 12 players, 5 Swiss roundsis optimal. That's enough for the leaders to meet a few times and a single winner to emerge, with places on equal points settled by the Buchholz coefficient.
A round-robin (everyone plays everyone) for 12 isn't used - it's 11 rounds and a whole day of play. The Swiss gives the same excitement four times faster. More on picking the round count in the how many rounds in the Swiss article.
On blitz 5+0 a round takes 12-15 minutes with seating (6 games run in parallel). Five rounds is about 1.5 hours. Blitz 3+2 wraps it in an hour; rapid 10+5 stretches it to 2.5-3 hours for more thoughtful games. For 12 people you need 6 boards - one per pair.
A classic scenario: 12 coworkers, a Friday evening, blitz 5+0, 5 rounds, a prize for the winner. Create the tournament in the bot Vibe Chess Bot with /create_tournament, open /open_registration (people sign up themselves), /start_tournament and /next_round between rounds. The finished table comes after /finish_tournament. More on the office format in the office tournament article.
Five Swiss rounds. That's enough for the leaders to meet and a single winner to emerge, with equal points broken by the Buchholz coefficient.
A round-robin for 12 is 11 rounds - a whole day of play. The Swiss gives the same result in 5 rounds, so for this size it's the one to use.
On blitz 5+0, about 1.5 hours (five rounds of 12-15 minutes). Blitz 3+2 - around an hour, rapid 10+5 - 2.5-3 hours, depending on how thoughtful you want the games.
Six - one per each of the 6 parallel games. With fewer, play in turns, but the tournament takes longer.
No problem: on an odd count the bot gives one player a BYE with a point each round. The 5-round plan stays the same.
Pairings are computed by bbpPairings, an open-source engine implementing the Dutch system by FIDE rules: score groups, floats on an odd field, colour alternation. Free to use.
The bot is constantly improved based on real tournaments. If you need a feature that isn't there yet, message the developers right inside the bot with the /support command. Many features appeared exactly because organizers asked for them, and useful ideas get added quickly.
A smaller group - 8-player tournament. A bigger one - 16-player tournament. The format - blitz in an evening. At the office - office tournament.
At the board since childhood: hazy about his rating, precise about every rook he has blundered. Counts an evening as a good one if the opponent stayed to talk afterwards instead of rushing off to check with an engine. Message →
