Tournament Seeding Calculator

Background.

This tournament seeding calculator turns an entrant count into a single-elimination bracket. It returns the bracket size, how many rounds the winner must survive, how many byes there are, how many matches are actually played in round one, the total match count, and who a chosen seed meets in the first two rounds.

Brackets have to be a power of two, because every round halves the field and you need to arrive at exactly two competitors for the final. USTA's Friend at Court puts it directly: when the number of players is 4, 8, 16, 32, 64, 128 or any higher power of two, they meet in even pairs in progressive elimination. Whenever the real entry list is not a power of two, the draw is filled out to the next one with byes, and those byes go to the seeded players in descending order — the top seeds skip round one.

Two numbers surprise people. The first is the total match count: it is always entrants minus one, no matter how many byes there are, because a knockout ends with one undefeated competitor and every match eliminates exactly one other. The second is that byes plus first-round matches always equal half the bracket, since every round-two line is filled either by a bye or by a first-round winner.

This page covers single elimination with standard 1-vs-N seeding, where seed 1 sits on the top line, seed 2 on the bottom line, and seed s meets seed (bracket size + 1 − s) in round one. It deliberately does not cover double elimination, consolation or compass draws, or third-place play-offs, and it reports the deterministic chalk position rather than the randomisation that USTA and the ITF apply within seed bands — the FAQ below explains each of those.

What is tournament seeding calculator?

A single-elimination or knockout tournament is one in which a single defeat ends a competitor's event. Seeding is the process of placing the strongest entrants at fixed positions in the draw so that they cannot meet until the later rounds, which protects the competition from a first-round collision between the two best players. The standard placement pairs seed s against seed (bracket size + 1 − s) in the opening round — 1 against the bottom line, 2 against the second-bottom, and so on — and separates the top two into opposite halves, the top four into different quarters, and the top eight into different eighths. USTA's regulations state the top of this rule explicitly: the first seed goes on the top line of the draw and the second seed on the bottom line. When the entry list falls short of a power of two, byes fill the gap and are awarded to the seeded players in descending order, which both rewards seeding and keeps the draw balanced. A bye in a bracket is a free pass into round two and is a different thing from a bye in a round-robin schedule, where it simply means a competitor is idle for one round of an odd-sized field.

How to use this calculator.

1. 01Enter the number of entrants in the draw — players, pairs or teams.
2. 02Enter the seed you want to follow. Seed 1 is the top seed; enter any number up to the entrant count.
3. 03Read the bracket size and rounds to size the event: rounds is how many wins the champion needs, and bracket size is the number of lines on the draw sheet.
4. 04Read the byes and first-round matches to plan day one. Only the first-round matches are played that day, and the byed seeds enter in round two.
5. 05Read the seed path for the traced seed's opening opponent and, on chalk, its round-two opponent. Treat it as a projection under the assumption that higher seeds win, not as a prediction.
6. 06For a league where everyone plays everyone rather than a knockout, use the round robin fixtures calculator instead — the two formats size completely differently.

The formula.

The bracket size is the smallest power of two at or above the entrant count, because a knockout halves the field every round and must land on exactly two competitors for the final. Twelve entrants therefore play a 16-draw; twenty-seven play a 32-draw. The round count is log base 2 of the bracket size, so a 16-draw is four rounds and a 64-draw is six.

Byes are the unfilled lines: bracket size minus entrants. USTA's rule is that they are added so that the second round has a competitor on every line, 'so that there can be an orderly progression down to two finalists', and that they go to the seeded players in descending order. That gives the arithmetic identity worth remembering: byes plus first-round matches always equals half the bracket, because every round-two line is filled either by a byed seed or by a first-round winner. USTA's own worked example is a 27-player draw — five lines of a 32-draw are marked bye, eleven first-round matches are played, and 5 + 11 = 16 competitors reach round two.

First-round matches is entrants minus half the bracket. For 12 entrants in a 16-draw that is 12 − 8 = 4, and the four matches are the ones between seeds 5 and 12, 6 and 11, 7 and 10, and 8 and 9, with seeds 1 to 4 idle.

The total match count is entrants minus one and does not depend on the byes at all. A single-elimination event finishes with one undefeated competitor, so exactly (entrants − 1) competitors must be eliminated, and each match eliminates exactly one. Twelve entrants therefore play eleven matches whether four of them start with a bye or not.

The seed placement follows the standard bracket rule: seed s meets seed (bracket size + 1 − s) in round one, and if that seed number is unfilled the higher seed takes a bye. Under chalk — every higher seed winning — the survivor of that pairing is min(s, bracket size + 1 − s), and the same rule applies again in a bracket of half the size, which gives the round-two opponent.

A worked example.

Frequently asked questions.

References& sources.

1. [1]USTA, Friend at Court 2026 — Handbook of Rules and Regulations, Regulation II.B 'Making the Draw' and Table 6 'Positioning Seeds'. Sources every rule this calculator implements: draws are 'a power of two' with players meeting 'in even pairs in progressive elimination'; 'the first seed shall be positioned on the top line of the draw, and the second seed shall be positioned on the bottom line'; byes are added when there are not enough players and 'shall go to seeded players in descending order'; and the worked 27-player example — five byes on a 32-draw and eleven first-round matches, joining 'to make up an even 16' in the second round — which this calculator reproduces exactly.
2. [2]FIFA, Regulations for the FIFA World Cup 26™ (May 2026), Article 12.1: 'The format of the final competition consists of a group stage, followed by the knockout stages with a round of 32, a round of 16, quarter-finals, semi-finals, the match for third place and the final.' Article 12.11 numbers the final as match M104. Cited for the worked knockout figures in the FAQ — a 32-entrant bracket is five rounds and 31 matches, and the published 32 knockout matches add the third-place play-off.
3. [3]Rasmussen, R. V. & Trick, M. A. (2008). 'Round robin scheduling – a survey.' European Journal of Operational Research, 188(3), 617–636. Cited for the definition of a bye in a scheduling context — 'in slots without a game they are said to have a bye' — and for the contrast drawn on this page between a round-robin bye (a competitor idle for one round of an odd field) and a bracket bye (a free pass into round two for a top seed).