Post-Event Rating Formulas
SwissSys supports multiple rating calculation formulas for different chess federations and tournament types.
Available Formulas
| Formula | Description | Usage |
|---|---|---|
| USCF | Modern USCF K-value based system | Default for US tournaments |
| Old USCF | Legacy USCF formula (pre-v4.0) | Historical compatibility |
| FIDE | International Chess Federation standard | FIDE-rated tournaments |
| Canada | CFC formula with special K-value handling | Canadian tournaments |
| Mexico | Mexican Chess Federation formula | Mexican tournaments |
| Custom Canada | Modified CFC variant | Customized Canadian events |
| CEA | Obsolete formula (no longer implemented) | Not available |
| Scholastic | Au Diapason system | Youth tournaments |
| British Chess Federation | BCF with 40-point max rating difference | UK tournaments |
| Chess’n Math | Chess’n Math of Canada with bonus points | Chess’n Math events |
Formula Selection
Select the appropriate formula based on:
- Federation requirements: USCF for US tournaments, FIDE for international events
- Tournament type: Scholastic formula for youth-focused events
- Regional standards: Canada/Mexico for federation-specific tournaments
- Historical compatibility: Old USCF for legacy data
Choose the formula before the tournament begins. Changing formulas mid-event may affect rating calculations.
K-Factor (K-Value)
The K-value determines rating change sensitivity:
- Higher K-values: Larger rating changes per game (more volatile)
- Lower K-values: Smaller rating changes per game (more stable)
Typical K-values:
- USCF Standard: 32 for players under 2100, 24 for players 2100-2199, 16 for players 2200+
- FIDE: 40 for new players (first 30 games), 20 for players under 2400, 10 for players 2400+
- Scholastic: Varies by system configuration
K-value values are set per player during registration. See Registration Editing for configuration details.
Scholastic Rating System
The Au Diapason scholastic formula has unique characteristics:
- Ratings never decrease: Losses do not reduce player ratings
- Not opponent-dependent: Rating changes based on performance, not opponent strength
- Youth-focused: Designed to encourage participation and improvement
For detailed scholastic rating configuration, see Scholastic Rating Setup.
Configuration
To set the rating formula for a tournament:
- Open Tournament Setup
- Select the desired Rating Formula from the dropdown
- Configure individual player K-values during registration
Federation-specific requirements: Verify formula selection matches federation requirements for official tournaments. Using the wrong formula may invalidate rating submissions.
Related Topics
- Ratings Overview - Understanding rating systems
- Registration Editing - Setting player K-values
- Scholastic Rating Setup - Detailed scholastic configuration
- Unrated Tournaments Cautions - Important rating considerations