A number that approximates a player's skill. The actual meaning of the number depends upon the issuing organization. FIDE ratings are used as the international standard for over-the-board chess.
A rating is a number that approximates a player's skill. In general, by comparing two players' ratings, one can gain an appreciation for the likelihood of one player defeating the other. Having ratings allows tournament organizers to group those with close ratings together, affording everyone challenging but winnable games.
Example for USCF rating system
United States Chess Federation (USCF) ratings are common for American players. By participating in USCF-sanctioned events, players earn ratings that are based upon their performance against other rated players.
Remember, ratings approximate skill. They are ever-changing and adapt in accordance to the results of games played. For the USCF rating system, players are playing for some share of the other players' rating points. That is, points won by the winner are taken from the losing player; it's a zero-sum system.
Players with equal ratings have equal chances of winning. A rating difference of 400 points means that the lower-rated player has virtually no chance of winning the game. A difference of perhaps 200 points means the lower-rated player will be challenged but should have a sporting chance.
How are rating points earned? The more the result of a game mirrors the expectation based upon the players' ratings, the fewer points are won or lost. Examples:
- If two players are equally rated, the winner will gain 16 points at the expense of the loser.
- According to the way the USCF system was designed, an 1800 should defeat a 1400 pretty much every game. If this happens, their ratings are deemed accurate and change very little, perhaps a point or so; the result affirms the relative ratings are accurate.
- However, if the 1400-rated player somehow wins, she gains a whopping 32 points at the expense of the 1800 rated player (who now becomes a 1768-player.) Their ratings are out of kilter and need a strong correction.
- Finally, an 1800 is expected to defeat a 1600 most of the time, but certainly not all the time. Thus if an 1800 defeats a 1600, the 1800 wins perhaps 10 points.
- Conversely, if the 1600 player were to win, the 1600 would gain about 22 points. As before, the players' ratings are adjusted to better reflect reality.
The actual system in use has plenty of tweaks in it - the above simply shows how it works in general.
The average club player is rated at 1500; Club players have ratings from E (low) to A (1800-1999), then labels such as 'Expert' (2000-2199), National Master (2200-2399), and Senior Master (2400+). The USCF does not grant International Master or Grandmaster titles.
Finally, bear in mind there are many rating systems. FIDE and the USCF both use similar systems invented by Arpad Elo). Other systems exist including the Glicko system.
