Running a trading card game tournament starts with one question: how many Swiss rounds? Too few and the standings are a coin-flip; too many and players sit around all day. This calculator gives you the recommended rounds for your attendance, the mathematical minimum, and the records players need to make the cut.
How it works
Swiss pairing matches players on equal records each round. Every round halves the pool that can still be undefeated, so to produce a single undefeated player you need at least:
minimum rounds = ⌈log₂(players)⌉
For example 32 players give ⌈log₂(32)⌉ = 5. Official organisers publish a fixed table keyed to attendance bands (the long-standing DCI table), which this tool uses for the recommended figure: 4 rounds up to 16 players, 5 up to 32, 6 up to 64, 7 up to 128, and so on.
Scoring is win = 3, draw = 1, loss = 0, so after r rounds the maximum is 3r points. A player who loses at most twice finishes “X-2” with 3(r − 2) points, which reliably makes a Top 8 at most events.
Quick reference by attendance
| Players | Recommended rounds | Min (log₂) | Suggested top cut | X-2 points |
|---|---|---|---|---|
| 4–8 | 3 | 3 | Top 2 / no cut | 3 |
| 9–16 | 4 | 4 | Top 4 | 6 |
| 17–32 | 5 | 5 | Top 8 | 9 |
| 33–64 | 6 | 6 | Top 8 | 12 |
| 65–128 | 7 | 7 | Top 8 | 15 |
| 129–226 | 8 | 8 | Top 8 | 18 |
X-2 points = 3 × (rounds − 2), and assumes the player has no draws.
Why recommended rounds exceed the log₂ minimum
The pure mathematical minimum guarantees exactly one undefeated player, but tournament organisers need more than that. The extra rounds in the recommended table serve a practical purpose: they spread out the standings so that a clean separation exists between the players who should make the top cut and those who should not.
With very few rounds, multiple players can share the same record with no clear ordering, forcing heavy reliance on tiebreakers — which are often opaque and can feel unfair to players. More rounds mean that the difference between a 5-0 and a 4-1 record is substantial, and tiebreakers only need to separate players with the same win count, where they are a reasonable differentiator.
How Swiss pairings work between rounds
After each round, Swiss software (or a tournament organiser by hand for small events) pairs players with the same or similar number of wins. In round 1, pairings are random. From round 2 onward, 3-0 players face other 3-0 players; 2-1 players face 2-1 players; and so on. This produces a field that converges on a small set of undefeated players at the top and a spread of records below.
Players who lose early do not drop out — they keep playing against peers with the same record. This is the key advantage of Swiss over single elimination: everyone plays all their rounds and has a defined record at the end, rather than going home after one loss.
Tiebreakers to know
When two players share the same point total at standings, tiebreakers determine who advances. The most common tiebreakers used in TCG events are:
- Opponents’ win percentage (OWP): The average win rate of everyone you played. Playing well-performing opponents raises your OWP. Receiving a bye in round 1 can lower it.
- Opponents’ opponents’ win percentage: The average OWP of your opponents. A second-order measure of schedule strength.
- Game win percentage (GWP): Your win rate at the individual game level (not match), rewarding players who win 2-0 more often than 2-1.
For sanctioned events, always confirm the current official tournament rules for your game and event tier, since premier events sometimes add a round or run a larger cut. All calculations run locally in your browser.