How many courts a draw of a given size actually needs
A single knockout of thirty-two takes thirty-one matches in five rounds, which is nine hours on four courts and six on eight, at an hour a match. The short answer is that the number of courts changes the length of the day far less than people expect, because the last three rounds cannot use more than four courts however many you have.
Thirty-one matches, five rounds, nine hours on four courts. The tables below say the rest.
The arithmetic, and the table it produces
A single knockout of N entrants plays N minus one matches in as many rounds as you can halve N: eight is three rounds, sixteen is four, thirty-two is five, sixty-four is six. A round of M matches on C courts needs M divided by C turns of the courts, rounded up, and a round cannot start before the round before it has finished.
The hours below assume an hour a match, which is what SetMatcher plans with until an organiser changes it. Read them as turns of the courts rather than as clock time: a format with shorter matches simply multiplies the same column by a smaller number.
Read one row across and the shape of the problem appears. Doubling the courts from two to four takes a draw of sixty-four from thirty-two turns to seventeen, which is most of a day saved. Doubling again, from four to eight, saves only seven more.
| Entrants | Matches | Rounds | Hours on 2 courts | Hours on 4 courts | Hours on 8 courts |
|---|---|---|---|---|---|
| 8 | 7 | 3 | 4 | 3 | 3 |
| 16 | 15 | 4 | 8 | 5 | 4 |
| 32 | 31 | 5 | 16 | 9 | 6 |
| 64 | 63 | 6 | 32 | 17 | 10 |
What limits you is the last round, not the first
The widest round of a knockout is the first, with half the field playing at once, and that is the round extra courts help. After it every round is half the size of the one before, so a semi-final is two matches whether you own four courts or forty. The last three rounds of any knockout take three turns of the courts and cannot be made shorter by owning more of them.
The practical consequence is that the useful number of courts is about half the field, and beyond that you are buying very little. If you have eight courts and thirty-two entrants, the first round fills all eight twice and every round after that leaves courts standing empty. That is the moment to consider a second draw beside the main one, which is what a plate is for.
A round robin is a different problem
A round robin has no rounds that halve. Every entrant plays every other, so N entrants play N times N minus one over two matches, and the field size hurts quadratically: eight entrants are twenty-eight matches, sixteen are a hundred and twenty. The number of rounds is N minus one when N is even and N when it is odd, because an odd field leaves somebody sitting out each round.
The turns in the table below are a lower bound rather than a schedule, and the difference matters. They divide the matches by the courts, but no player can be on two courts at once, so a real round robin often needs one turn more than the arithmetic suggests. The page on running a doubles round robin gives the method that avoids that.
| Entrants | Matches | Rounds | Turns of 2 courts | Turns of 3 courts | Turns of 4 courts |
|---|---|---|---|---|---|
| 4 | 6 | 3 | 3 | 3 | 3 |
| 6 | 15 | 5 | 8 | 5 | 5 |
| 8 | 28 | 7 | 14 | 10 | 7 |
| 10 | 45 | 9 | 23 | 15 | 12 |
| 12 | 66 | 11 | 33 | 22 | 17 |
| 16 | 120 | 15 | 60 | 40 | 30 |
The two things that make a real day longer
Rest. A player who has just come off court cannot start the next round immediately, and in a knockout the winners of round one are exactly the people round two needs. SetMatcher lets an organiser set a rest period between a player’s matches of anywhere from five minutes to six hours, and the schedule respects it rather than producing a plan the players cannot follow.
And the long match. The tables assume every match takes the same time, and none of them do. One three-setter in the quarter-finals holds up a court, and because a round cannot start before the round before it has finished, it holds up everybody. Plan the widest round tightly and leave slack in the last three, which is the opposite of what most draw sheets do.
What SetMatcher does with all of this is make the order of play for you from the courts you say you have, the length you say a match takes and the rest you insist on, and then let the desk move a match when the day slips. Up to 16 entrants that is free with everything in it; above that it belongs to the event, and the pricing page says what that costs.
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