The fairest format there is, and the one with the hardest ceiling. Nobody can be favoured by the pairing because the opposition is identical for all - but the number of games grows with the square of the field, and past a dozen players it stops fitting into any calendar. Here is how many rounds you need, how the colours are decided, what to do with an odd field, and how places are settled when players finish level.
Every player meets every other player exactly once. The event is paired a single time: participants draw starting numbers before round one, and from then on the whole schedule comes from a standard table. Nothing is recalculated between rounds the way it is in a Swiss.
One fewer than the field if it is even, equal to the field if it is odd. Eight players play seven rounds; seven players also play seven, with each of them sitting out once.
Decided by the table: in every listed pair the first number has White. The distribution is nearly even - with an even field half the players get one extra White and the rest one extra Black.
Carries no advantage: everybody faces the same field. It affects only the order of the games and which colour you hold in each of them.
The time estimates assume blitz or rapid. This table is the whole argument about where the format stops working.
| Players | Rounds | Games | Rough time |
|---|---|---|---|
| 4 | 3 | 6 | about an hour of blitz |
| 6 | 5 | 15 | an evening of blitz or two of rapid |
| 8 | 7 | 28 | a long evening of blitz |
| 10 | 9 | 45 | two evenings |
| 12 | 11 | 66 | a weekend or a club month |
| 16 | 15 | 120 | a club season on a schedule |
Past sixteen players the format stops fitting a reasonable calendar: twenty players means 19 rounds and 190 games. For fields that size the answer is a Swiss, where 5 to 9 rounds suffice however many people turn up. If you are unsure which format fits your evening, the format picker works it out from your field, time control and hours.
For an odd number of players you take the pairing table one number up: seven players use the table for eight. Whoever is drawn against the number nobody holds is free that round, and over the event each player sits out exactly once.
How many points that free round scores is up to your regulations - a full point in club events, sometimes a half or zero in rated ones. Worth knowing that a bye also affects the tie-breaks, and not in your favour: the details are in odd number of players.
Here the round-robin differs from a Swiss in a way that catches organizers out. Buchholz - the standard Swiss measure - does not work at all and is explicitly ruled out by the regulations: everyone faced the same field, so the sums of the opponents' scores coincide and separate nobody.
The primary measure. The sum of the final scores of the opponents you beat, plus half the scores of those you drew with. You can compute it from a filled-in crosstable in the calculator.
Points scored against opponents who finished on 50 percent or better. Blunter than Sonneborn-Berger and sometimes disagrees with it - see the Koya system.
Always applicable here, because any two players are guaranteed to have met. Many round-robin regulations list it first for exactly that reason: how it is computed.
In the Vibe Chess app you pick the round-robin format, add the players including guests without Telegram, and the full schedule is built from the field automatically - no printed pairing tables required. Results go in with a button after each game, the standings order players level on points by the Sonneborn-Berger score, and the finished event exports as a TRF report.
With an even field, one fewer than the number of players: eight players means seven rounds. With an odd field, as many rounds as there are players, and each of them sits out once. The total number of games is always N×(N-1)/2.
Up to ten or twelve. Beyond that the volume grows faster than any evening can absorb: sixteen players means fifteen rounds and 120 games. Larger fields switch to the Swiss system.
By the pairing table: in each listed pair the first number has White. The tables are built so that colours alternate almost perfectly - with an even field half the players get one extra White and the rest one extra Black.
By the Sonneborn-Berger score: the sum of the final scores of the opponents you beat plus half the scores of those you drew with. Buchholz does not work here and is explicitly ruled out, because everybody faced the same field. After Sonneborn-Berger come the Koya system and the direct encounter.
The same pairings are played twice with the colours reversed. FIDE recommends swapping the last two rounds of the first cycle when building the second, so that nobody ends up with three games in a row on one colour at the join.
It hurts more than in a Swiss, because the schedule assumes the full field. The usual practice is to award wins without play to their remaining scheduled opponents while keeping the games already played - and to state in advance what happens if the leaver completed fewer than half of their games.
In one specific sense, yes: everyone faces the same opposition, so the pairing cannot favour anybody. The price is size - it only works for a small field. A Swiss handles any number of players but produces different paths, which is why it needs tie-breaks to sort out ties.
Yes, once, before round one. The starting number determines nothing about strength - the opposition is identical for everyone - but it fixes the order of the games and the colours. After that the schedule runs itself.