How to organise a doubles round robin
Count the matches first: eight pairs is twenty-eight matches and seven rounds, which is fourteen turns of two courts. If that fits the afternoon, build the rounds with the circle method, keep one pair fixed and rotate the rest, and give an odd field a sit-out each round rather than a bye.
Count the matches, build the rounds with the circle method, date them a week apart.
What it costs in matches and in court time
N entries play N times N minus one over two matches, in N minus one rounds when N is even and N rounds when it is odd. Six pairs is fifteen matches in five rounds; twelve pairs is sixty-six matches in eleven. The jump between those two is what catches people out, because the field only doubled.
The turns in the table are the matches divided by the courts, rounded up, and they are a floor rather than a plan: nobody can be on two courts at once, so a schedule that ignores who is playing will often need one more turn. The circle method below is what avoids that, because it builds rounds in which every entry appears at most once.
| Pairs entered | 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 circle method
Write the entries in two rows of equal length, one above the other, and pair each column: that is round one. Then hold the entry in the top left corner still and rotate every other position one place clockwise around it. Pair the columns again and you have round two. Repeat until you are back where you started, which takes N minus one rotations.
With an odd number of entries, add an imaginary one to make the rows equal. Whoever is paired with the imaginary entry sits that round out, and because the rotation moves everybody, the sit-out travels around the field so that nobody sits out twice before everybody has sat out once.
This is what SetMatcher builds when you make a round robin, so the rounds come out balanced without anybody drawing circles on paper. It is also why a round robin has rounds at all: the matches could be played in any order, but the rounds are what let a league be dated and a social afternoon be called out one round at a time.
In doubles, a pair is one entry
A doubles round robin on SetMatcher is a round robin of pairs. The pair enters, the pair appears in the table, the pair wins or loses, and eight pairs means sixteen people on court across twenty-eight matches. Read every number on this page as pairs and the arithmetic is the same as for singles.
A format in which partners change every round is a different thing, and it is not what a round robin means here. If you want everybody to play with everybody, you are organising a rotation rather than a competition, and its table is a table of individuals rather than of entries. SetMatcher runs the competition rather than the rotation.
One consequence is worth saying plainly: in a doubles round robin every player needs a partner who is available for every round, which is the real constraint on the size of the field. Eleven rounds over eleven weeks is eleven evenings two people both have to be free, and a field that looks fine in February empties in June.
Dating the rounds of a league
A round robin played over weeks rather than in one afternoon needs a date per round, and SetMatcher gives it one: a play-by date, a week apart by default and anywhere from a day to a year if you say so. It is the deadline the two sides have until, never a time anybody agreed to play at.
The distinction matters and it is why the date sits on the round rather than on the match. A match acquires a time when its two sides agree one, and until then it has none. Each side can also play the whole cycle again with the sides of every fixture swapped, which is what a double round robin is everywhere it is published; anything above two legs is refused, because a friends’ league is not a season.
Where to read next
More on the subjects you have just read about.
Your first match is one tap away.
Free for players. Clubs get a register, a park map, court bookings and lessons.