How many rounds should a Swiss event have?

About log₂ of the number of players, rounded up. Eight players need three rounds, sixteen need four, and sixty-four need six.

Will anyone play the same opponent twice?

Not while a rematch-free pairing exists — the search backtracks to find one. Past the point where none exists, every forced rematch is flagged.

What happens with an odd number of players?

One player gets a bye, conventionally scored as a win. It goes to the lowest-placed player who has not already had one.

Does this follow FIDE rules?

No. It is a practical generic Swiss pairing — score-grouped, rematch-avoiding and bye-fair — and does not implement any federation's published system.

Swiss Pairing Generator

Pairs a round of a Swiss tournament: players on similar scores meet, nobody plays the same opponent twice while an alternative exists, and an odd field shares the bye out fairly. Everyone plays every round, so a field of any size resolves in a handful of rounds without anybody being eliminated.

Players

One per line. For later rounds add the score, then a pipe and who they have played: Ana 2 | Ben, Chi

8 players — 3 rounds usually separate a field this size

No scores were given, so everyone is on zero — that is exactly right for round one.

Round number

For labelling. The pairings come from the scores and histories above.

Seed (optional)

A word that makes the draw reproducible when ties are randomised.

Break ties between equal scores at random

Your pairings will appear here.

What this generator does

Sits between the two formats already on this site. A round-robin plays everyone against everyone and needs n−1 rounds, which is far too many for a large field. A knockout takes only log₂(n) rounds but removes half the entrants immediately. Swiss keeps everyone playing for a fixed, small number of rounds and uses results to decide who meets whom, so the field sorts itself as it goes.

How to use this tool

For round one, enter the players one per line — that is all you need.
For later rounds, add each player's score, then a pipe and who they have already played: Ana 2 | Ben, Chi
Set the round number and press Pair this round.
Play the round, update the scores and histories, and paste the list back in for the next one.

Understanding the controls

Players: One per line. A trailing number is that player's score, and anything after a pipe is who they have already faced — so the same box carries the whole standings, and round one is just a list of names.
Round number: Used for labelling only. The pairings themselves come from the scores and histories you supply, not from the round number, so you cannot get a wrong pairing by mistyping it.
Break ties at random: On, players with equal scores are shuffled before pairing, which is fairer across a whole event. Off, they are taken in the order you typed them, which is reproducible without needing a seed.
Seed: Fixes the tie-breaking shuffle so a round can be reproduced exactly — useful when the printed pairings are lost and a fresh random draw would contradict what players were told.

Worked examples

Eight players: Four boards a round, and three rounds usually separate the field.
Sixteen players: Eight boards a round over four rounds — 32 games instead of the 120 a round-robin would need.
Seven players: Three boards and one bye each round, with the bye moving to a different player every time.

Common use cases

A chess club evening or a weekend congress
A trading-card game tournament, where Swiss is the standard format
A board-game convention event with too many players for a round-robin
A quiz or debating league that needs several rounds and a final table
Any competition where knocking half the field out after one round would be wrong

How this generator works

Players are sorted by score, then paired down the list by backtracking search: the highest unpaired player takes the nearest-scoring opponent they have not already met, and the search backs up whenever a choice would leave the rest of the field unpairable. That backtracking is the part that matters — a simple pass that pairs first with second, third with fourth and so on fails as soon as two adjacent players have met, which happens most often in exactly the late rounds that decide the standings. If the field is odd, the bye goes to the lowest-placed player who has not already had one.

Randomness and fairness

Randomness only ever breaks ties between players on equal scores; everything else follows from the results you enter. That is worth being clear about, because Swiss is often described as a random draw and it is not — the pairing is determined by the standings, and two organisers with the same scores and histories will produce very similar rounds. A seed replaces the tie-breaking shuffle with a deterministic, non-cryptographic generator so a round can be recreated.

For how randomness is produced across the whole site, see how Generate Random works.

Limitations and good to know

This is a practical generic Swiss pairing, not an implementation of any federation's published rules. FIDE's Dutch system and its relatives specify transposition and exchange orders, float history and acceleration in detail, and none of that is implemented here.
Colours — white and black, or home and away — are deliberately not assigned. A half-implemented colour balance looks like the real thing and is not, so the tool omits it rather than approximating it.
Tie-breaks such as Buchholz or Sonneborn–Berger are not calculated. The standings shown are raw scores, and a real event usually needs a tie-break to separate equal finishers.
The tool pairs one round at a time from the data you give it. It has no memory between rounds, so you have to carry the scores and histories forward yourself.
With very few players relative to rounds, rematches eventually become unavoidable — the tool flags every one rather than hiding it.

Common mistakes

Forgetting to add opponents to the history: Without the history the tool cannot avoid rematches. Add each opponent to both players' lists after every round, or you will see repeat pairings it had no way to prevent.
Running too many rounds for the field: About log₂(n) rounds separates a field — three for eight players, four for sixteen. More rounds than that produce forced rematches and a leader who was already clear.
Treating the bye as a bye rather than a win: Convention is to score a bye as a full point. If you score it as zero the player is punished for an accident of the field size.
Expecting the tool to assign colours: It does not, on purpose. Alternate colours yourself, or toss for the first board and alternate down the list.

Practical tips

Keep the whole standings in one text file and edit it between rounds — the format the tool reads is the same format you paste back in.
Announce before round one how many rounds you are playing; Swiss standings only make sense against a fixed number.
If two players finish level, you will need a tie-break rule agreed in advance, because the raw score will not separate them.

Privacy and your data

Player names, scores and histories are processed in your browser and never uploaded. Nothing is stored between visits and nothing reaches the page address, so pairings cannot leak through a shared link — copy or print them instead. Analytics records only how many boards were paired.

Frequently asked questions

How many rounds should a Swiss event have?: About log₂ of the number of players, rounded up. Eight players need three rounds, sixteen need four, and sixty-four need six.
Will anyone play the same opponent twice?: Not while a rematch-free pairing exists — the search backtracks to find one. Past the point where none exists, every forced rematch is flagged.
What happens with an odd number of players?: One player gets a bye, conventionally scored as a win. It goes to the lowest-placed player who has not already had one.
Does this follow FIDE rules?: No. It is a practical generic Swiss pairing — score-grouped, rematch-avoiding and bye-fair — and does not implement any federation's published system.