How it works
A 21 team round robin is 210 games, each team meeting the other 20 once. Somebody has no opponent in every round, which makes 21 rounds of ten games. The example plays 15-minute games on ten courts, 10:00 to 3:15 pm.
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Three pools of seven, or seven groups of three
Twenty-one splits evenly two ways. Three pools of seven play 21 games each, 63 in all, over seven rounds with one rest per team. Seven groups of three play three games each: 21 in all, a tenth of the full 210. From seven groups, the winners and the best runner-up fill an 8 team bracket.
Game length decides the day
On ten courts the day is 21 slots long: 5 hours 15 minutes at 15 minutes a game, 7 hours at 20, 10 hours 30 at 30. Minutes per match has to cover the changeover too, because 19 of the 21 teams play again in the very next slot. With five to nine courts every figure doubles.
- The resting team is the only spare one in a round: hand it the scoreboard. Every team gets one turn.
- Twice (double) is 42 rounds and 420 games, 40 for each team.
- Four courts or fewer run past midnight at 15 minutes a game: clear First match starts and play a round a week.
Questions and answers
Can a 21 team league stop before all 21 rounds are played?
Yes. Stop after any round and no pair has met twice. After round 14, the 14 teams that have had their rest have played 13 games and the other seven have played 14, so rank on points per game.
Is one round robin fairer than pools for 21 teams?
Yes, at a price. In one round robin every team plays all 20 others, so nobody gains from an easy draw. Pools of seven cut 210 games to 63, but each team meets only six of the other 20.
Does every team get the same number of home games with 21 teams?
Yes. Each team plays 20 games and is named first, the home side, in exactly ten. An even field cannot manage that: with 22 teams, half get eleven home games and half get ten.