How ratings are calculated
Rating and confidence
Ratings are Glicko-2, which tracks two numbers: your rating, its guess at how good you are, and your rating deviation (RD), how sure it is of that guess. You start at 1500 with an RD of 350. Each game pulls the rating towards the result and shrinks the RD, and beating someone stronger moves you further. Only the winner counts: the score is recorded but never used, and there are no draws.
- 1500 beats 1700
- +39.3
- 1700 loses to 1500
- −39.3
- 1700 beats 1500 instead
- +13.1
- 1500 loses to 1700
- −13.1
The upset pays about three times the expected result.
Why the board sorts by rating − 2 × RD
The ranking uses your rating minus twice your RD — roughly the rating you have proven, rather than the one you might have. New players sit at 800 however good they are, so climbing means playing games to shrink your RD, not only winning them. The Rating column shows the raw rating; the sort order does not.
| board position | = | rating − 2 × RD |
The band is everything the rating cannot rule out. The board sorts on its left edge, so a wide band ranks low however high the rating sits.
- On joining
- 1500 − 2 × 350 = 800
- After 5 wins
- 1842 − 2 × 170 = 1501
Most of the climb comes from the RD collapsing, not the rating rising.
A team becomes one opponent
Glicko-2 rates one player against one opponent, so the other team is collapsed into a single virtual opponent: the mean of their ratings, and the root mean square of their RDs. Both teammates face that same virtual opponent, but their changes differ, because of the two adjustments below.
Your teammate is rated the same way, in their own separate calculation against the same virtual opponent.
| virtual rating | = | mean(their ratings) − carry + handicap |
| virtual RD | = | √( (RD₁² + RD₂²) ÷ 2 ) |
Being carried is worth less
Your virtual opponent's rating is shifted by 20% of half the gap between you and your teammate. Play beside someone stronger and it is treated as weaker, so the win pays less; carry someone weaker and it is treated as stronger, so you get credit. It is only a nudge: Glicko's underdog bonus still outweighs it, so the weaker player on a lopsided winning team gains far more than their partner.
| carry | = | 0.2 × (teammate rating − your rating) ÷ 2 |
Only the virtual opponent moves — your teammate's rating never enters your own calculation directly.
- The 1000, partnered with a 1000
- +51.2
- The 1000, carried by a 2000
- +48.6
- The 2000, partnered with a 2000
- +3.3
- The 2000, carrying a 1000
- +5.4
Being carried costs a couple of points; doing the carrying pays a couple more.
Uneven teams: 1v2
When the teams are different sizes, the solo player is treated as 100 points weaker than their rating. Glicko only ever sees the gap between two ratings, so this lands as a shift with opposite signs: the outnumbered player's virtual opponent goes up by 100, and the pair's goes down by the same. Going solo pays more for a win and costs less for a loss; beating someone you outnumber pays less than beating an even-sized team, and losing to them costs more.
| handicap | = | +100 outnumbered, −100 outnumbering, 0 when even |
The outnumbered player faces a nominally stronger opponent; the pair faces a nominally weaker one. That is what stops a pair from farming rating off a solo player.
- Solo player wins
- +32.8
- …each member of the losing pair
- −32.8
- Solo player loses
- −19.0
- …each member of the winning pair
- +19.0
- For comparison: an even-sided win
- +25.8
The solo player's win beats the +25.8 even-sided baseline; the pair's win falls short of it. Per head the two sides now mirror each other.