Building a custom format
If none of the built-in systems matches how your tournament actually runs, compose your own. The tournament system builder snaps phases together, validates the result, and previews it against a team count before you commit to anything.
You reach it two ways: Settings → Schedule & format → Tournament systems → Build a custom format to apply it to the tournament you are in, or the standalone system builder to design one and save it for reuse. Same composer either way.
Phases
A format is an ordered list of phases. Each one is a round-robin groups stage, a single table, or a knockout bracket, and carries its own settings:
Round-robin groups
- Group size — how many teams in each group.
- Partition — Balanced spreads strength evenly across groups, the ordinary draw. Stratified (ladder) stacks by strength instead, so the top group holds the strongest teams. Stratified is what makes a ladder work.
- Rounds — Once for a single round-robin, Twice for home and away.
- Days and Day spread — Even spreads the phase's matches across its days, Packed front-loads them.
Single table
One pool, everyone ranked together, no group split.
Knockout bracket
The bracket. Its qualification and seeding defaults are the ones described in knockout brackets. Start on the group stage's final day runs the cup on the last round-robin day — a round-robin-plus-cup day — so the whole tournament fits in one. Leave Days at 1 for that; set it to 2 only if the cup should overflow.
How teams move between phases
Each phase after the first declares how it is fed:
| Rule | What happens |
|---|---|
| Top teams from each group | The top n of every group go through. |
| Re-seed ladder | Group winners climb a tier, bottom finishers fall, and the groups re-form. |
| Peer cups | Each tier plays its own cup final. |
| Rank the whole field | Everyone is ranked across all groups into one order. |
| Everyone carries over | The whole field moves on unchanged. |
Where a ladder promotes and relegates, Promoted per group and Relegated per group set how many move each way. Where the field is ranked, Teams carried forward keeps only the top n — leave it at 0 to carry everyone — and Ranking order decides whether the combined order interleaves positions (all winners first, then all runners-up) or takes one group after another.
Seeding
The whole format declares how its first phase is seeded:
- Registration strength — the strength value that came in with the team list.
- OpenSkill rating — the rating learned from played results.
- Manual — the order you set.
- Random — a draw.
- Carryover — the order the previous phase finished in.
Arrival / rest days adds leading days with no matches, for a travel day before play starts.
Preview and validation
The panel previews live against a preview team count: how many days the format takes, how many groups on day one, how many teams enter the knockout, how many phases come later, and a per-phase day breakdown. Anything invalid says so — This format isn't valid yet — rather than letting you apply a format that cannot be built.
The full system definition is available as JSON if you want to read exactly what you composed.
Applying it
Apply system builds the format into a tournament's days, groups and fixtures. It replaces any existing structure: if the tournament already has matches, you are asked first, and the existing days, groups and matches are deleted and rebuilt. Your teams are always kept.
Save the format as a template to use it again — see reusing a setup. A saved custom system is what a template applies when you scaffold next year's edition, which is what makes the whole thing worth doing once.
A format that only works at exactly 24 teams is a format you will rebuild. Step the preview count through the sizes you plausibly get — 20, 24, 28 — and check it stays valid before you save it.