Tournament Brackets in Tennis: How to Draw and Seed Them

Bracket size

A knockout bracket is clearest when the number of spots is a power of two: 8, 16, 32. Then each round halves the number of players, and the tournament ends with a final with no exceptions.

With any other number of participants, the bracket grows to the nearest power of two, and the empty spots are filled with byes.

Byes

A bye means a player advances to the next round without playing. The number of byes is the difference between the bracket size and the number of participants. With twelve players the bracket has sixteen spots, so there are four byes.

Byes go to the top seeds, not to random players. That way the first round is played by those with the smallest chance of winning the tournament, and the favorites enter from the second round.

Seeding

Seeding means placing the best players in the bracket so they do not meet too early. The rule is simple: seeds one and two go to opposite ends of the bracket and can meet only in the final. Seeds three and four go to the remaining quarters, so they can meet the top seeds in the semifinals at the earliest.

The rest of the players are drawn into the open spots. The bigger the bracket, the more seeds make sense: an eight-person bracket needs two seeded spots, a sixteen-person one usually four, and a thirty-two-person one eight.

Example: twelve people

Twelve participants need a sixteen-spot bracket, which means four byes. They go to seeds one through four, so only the players in spots five through twelve play the first round: four matches. In the second round the seeds enter and eight players remain, then four semifinalists and the final.

That adds up to eleven matches, the same as the number of participants minus one. The math always works and gives you a quick check that the bracket was built correctly: if you count differently, there is an error in the diagram.

Where to get a ranking for seeding

Best from results: the last tournament, a league or a rating. In Tenisime, the Organizer panel has an option to seed by the participants' ELO rating: the highest ELO gets number one. If you have no ranking, do a fully random draw with no seeding, and state that in the rules.

What about players who lose in the first round

In a knockout bracket half of the participants finish the tournament after one match, which can be disappointing when there is an entry fee. There are two simple solutions: an extra consolation bracket for first-round losers, or double elimination, where after your first loss you drop into the losers' bracket and can still win the tournament.

Both solutions make the tournament longer, so work out the time before you promise them to participants.

The most common mistakes when drawing

The best cure for accusations is transparency: show how you seeded the players and publish the bracket right after the draw.

• drawing after sign-ups but before the list closes: someone who signs up later breaks the bracket
• handing out byes at random instead of to the top seeds
• players from the same club meeting in the first round when they could have been separated
• no information on when and where the draw happens, which leads to accusations about the layout
• changing the bracket after the draw without a clear reason