In a round robin everyone plays everyone once. The number of matches is the number of ways to pick two players from the group, which is what COMBIN does. Eight players is 28 matches. Spread those over the courts you have and round up, and you know how many rounds the afternoon needs — before you have promised 16 people it will be done by four.
Eight players is COMBIN(8,2) = 28 matches. On two courts that is 14 rounds; at 15 minutes a round, three and a half hours.
The example
Three social events. The 12-player event on four courts looks efficient until you see it is still 17 rounds, because only 4 matches can run at once and 12 players fill just 4 courts anyway.
| A | B | C | D | E | F | G | |
|---|---|---|---|---|---|---|---|
| 1 | Event | Players | Courts | Min/round | Matches | Rounds | Hours |
| 2 | Tuesday social | 8 | 2 | 15 | 28 | 14 | 3.50 |
| 3 | Club ladder day | 12 | 4 | 15 | 66 | 17 | 4.25 |
| 4 | Beginner clinic | 6 | 1 | 12 | 15 | 15 | 3.00 |
The formula
Matches, then rounds, then hours — each one a column the organizer can show the members:
How it works
COMBIN does the counting that people otherwise do on a napkin:
COMBIN(B2,2)is the number of unordered pairs in a group of B2. It equals n(n−1)/2: for 8 players, 8 × 7 / 2 = 28./C2divides matches across courts. 28 matches on 2 courts is 14 rounds if every round fills both courts.ROUNDUP(...,0)handles the uneven last round. 66 matches on 4 courts is 16.5, so 17 rounds.*D2/60converts rounds into hours at a fixed minutes-per-round. Add changeover time to the minutes if your courts are far apart.
For doubles, the players are teams: COMBIN(teams, 2). Eight players in fixed pairs is four teams and six matches. If partners rotate, it is a different and much messier problem — use a published rotation chart.
Try it: interactive demo
Enter the players (or teams), courts available, and minutes per round.
Variations
Courts needed to finish in a set time
Flip it: matches divided by the rounds that fit in the window, rounded up, is the courts you need to book.
Matches per player
Every player plays everyone else once, so it is simply players minus one. Useful for telling members how many games they get.
Pitfalls & errors
Rounds is a floor on the schedule, not the schedule. With an odd player count someone sits out every round, and a naive court assignment can leave a court idle while two players wait on each other. Use a rotation chart for the actual pairings.
COMBIN grows fast. Sixteen players is 120 matches; on four courts that is 30 rounds and a very long day. If the number surprises you, split into two pools and play a final.
Do not use PERMUT. It counts A-vs-B and B-vs-A separately and doubles every match count.
Practice workbook
Frequently asked questions
Does COMBIN work in older versions of Excel?
B2*(B2-1)/2 gives the same number.How do I handle a player who leaves early?
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