Backgammon – Rating System
Overview
The game uses the Glicko-2 rating system. Your rating updates immediately after each game based on the outcome and your opponent's rating.
Your Rating Profile
1. Rating (R) - Default: 1500.0
Your skill level. Higher numbers mean stronger players.
- New players start at 1500.0
- Rating changes based on game results
- Opponent strength affects point changes
- Win/loss impact depends on opponent's Rating (R)
- Shown rounded to 1 decimal; ties are broken by the exact value
2. Rating Deviation (D) - Default: 500
Uncertainty about your true skill
- High Deviation (D) = System is uncertain about your skill
- Low Deviation (D) = System is confident in your rating
- Playing games reduces your Deviation (D)
- Not playing increases your Deviation (D) over time (max 500)
3. Volatility (V) - Default: 0.09
How consistent your performance is
- Low Volatility (V) = Consistent player
- High Volatility (V) = Unpredictable results
How Ratings Change
Immediate Updates
Your rating changes instantly after each game for immediate feedback
Regular Wins
- Beating higher-rated opponents: Large rating gain
- Beating similar opponents: Moderate rating gain
- Beating lower-rated opponents: Small rating gain
Gammon Wins
Gammon wins count as 2 games, giving roughly double the rating impact.
Losses
The same logic applies in reverse - losing to lower-rated players hurts more than losing to higher-rated players.
First-Player Advantage
Player 1 (who rolls first) wins slightly more often against equal opponents — roughly 52% of the time, measured from actual games. To compensate, Player 2 gains a bit more on a win and loses a bit less on a loss.
Being Inactive
- Your rating stays the same (no rating decay)
- Your Deviation (D) increases (system becomes less certain)
- Maximum Deviation (D) is capped at 500
Matchmaking
Standard Matching (40-60% win probability)
- Rating range: ±400 points
- Considers Rating (R) and Deviation (D)
After Long Wait (±600 rating range only)
- Rating range gradually expands to ±600 points
- Match quality gradually relaxes
Bounds and Limits
- Volatility (V): max 0.1
- Deviation (D): 45-500
- Rating (R): minimum 400, no upper cap; calculations prevent extreme swings
Tips
- Play regularly to keep Deviation (D) low
- Play 5+ games per session for accurate Volatility (V) measurement
- Don't worry about losses - the system accounts for opponent strength
- Gammon wins give double impact - but so do gammon losses