Pair Numbers
Pair numbers determine player ranking and pairing eligibility. SwissSys assigns and manages pair numbers automatically based on player ratings.
Automatic Pair Number Assignment
By default, pair numbers are based on player ratings, with the highest-rated player assigned pair number 1. SwissSys handles this automatically when the “Sort new players” setting is enabled in the Environment Options dialog (Registration and Editing tab).
The “Sort new players” setting is enabled by default. This ensures consistent pair numbering based on player strength.
Manual Assignment (When Sort New Players is Off)
If you disable “Sort new players,” players will be assigned pair numbers sequentially in the order they are registered, regardless of rating. This is rarely used but may be helpful in specific tournament formats.
Rating Changes and Pair Number Updates
When you modify a player’s rating, SwissSys automatically updates all pair numbers to maintain correct ranking—but only if “Sort new players” is enabled.
If “Sort new players” is disabled, rating changes will NOT update pair numbers. You would need to manually reassign them or re-enable automatic sorting.
FIDE Mode Pair Number Restrictions
FIDE rules impose strict limitations on pair number changes after tournament has begun:
| Round | Pair Number Changes Allowed |
|---|---|
| Rounds 1-3 | Yes - can reflect late registrations and rating updates |
| Round 4 onwards | No - pair numbers are frozen and cannot change |
Once the fourth round starts, FIDE rules prohibit any changes to pair numbers, even if you add new players or update ratings. This is because FIDE pairings are based on pair number (not current rating), and stability is critical for rule compliance.
Equal Rating Handling
When two players have the same rating, SwissSys sorts them differently depending on your federation mode:
FIDE Mode
Players are sorted by:
- Rating (highest first)
- Chess title (higher title first)
- Last name (alphabetically)
USCF Mode
Players are sorted strictly by rating, with equal-rated players sorted randomly by default.
You can modify this behavior in the Environment Options dialog (Registration and Editing tab):
- Enabled (default): Equal-rated players are randomized
- Disabled: Equal-rated players are sorted first-come-first-served (registration order)