Chess rating systems
Encyclopedia
A chess rating system is a system used in chess
to calculate an estimate of the strength of the player, based on his performance versus other players. They are used by organizations such as FIDE, the US Chess Federation (USCF), International Correspondence Chess Federation
, and the English Chess Federation
. Most of the systems are used to recalculate ratings after a tournament or match but some are used to recalculate ratings after individual games. In almost all systems a higher number indicates a stronger player. In general, a player's rating goes up if he performs better than expected and down if he performs worse than expected. The magnitude of the change depends on the rating of his opponents. The Elo rating system
is currently the most widely-used.
The first modern rating system was used by the Correspondence Chess League of America in 1939. Soviet player Andrey Khachatoruv proposed a similar system in 1946. The first one that made an impact on international chess was the Ingo system in 1948. The USCF adopted the Harkness system in 1950. Shortly after, the British Chess Federation started using a system devised by Richard W. B. Clarke
. The USCF switched to the Elo rating system
in 1960, which was adopted by FIDE in 1970 .
. It influenced some other rating systems. This is a simple system where a player's new rating is the average rating of his competition minus one point for each percentage point above 50 obtained in the tournament. Unlike most other systems, lower numbers indicate better performance .
, who published it in 1956. It was used by the USCF from 1950 to 1960 and by some other organizations.
When a player competes in a tournament, the average rating of his competition is calculated. If the player scores 50% he receives the average competition rating as his performance rating. If he scores more than 50% his new rating is the competition average plus 10 points for each percentage point above 50. If he scores less than 50% his new rating is the competition average minus 10 points for each percentage point below 50 .
(formerly British Chess Federation) Grading System was devised by Richard W. B. Clarke
and first published in 1958. Points are scored for every game played in a registered competition (generally, English congresses, local and county leagues, and other team events). A player's grade is calculated by taking the opponent's grade and adding 50 points for a win, subtracting 50 points for a loss, and taking the opponent's grade as it stands for a draw. For grading purposes it is assumed that the opponent's grade is never more than 40 points above or below one's own. The ECF grades approximately 200,000 games a year. The grading season runs from 1 June to 31 May. An ECF grade can be approximated to an Elo rating by multiplying by 8 and adding 600. An ECF grade of 100 is approximately 1400 Elo, while 200 ECF equals 2200 Elo.
and is the most common system. It is used by FIDE and other organizations.
FIDE classifies tournaments into categories according to the average rating of the players. Each category is 25 rating points wide. Category 1 is for an average rating of 2251 to 2275, category 2 is 2276 to 2300, etc. For women's tournaments, the categories are 200 rating points lower, so an Category 1 is an average rating of 2051 to 2075, etc.
The USCF uses a modification of the Elo system, where the K factor varies and there are bonus points for superior performance in a tournament. The USCF classifies players according to their rating . USCF ratings are generally 50 to 100 points higher than the FIDE equivalents .
, a 2635-rated player, in an actual tournament of 16 players, and scored 10½ points. First the difference in rating is calculated for each other player, subtracting the other player's rating from Portisch's rating. Then the expected score against each player is determined from a table, based on this rating difference. For instance, one opponent was Vlastimil Hort
, who was rated at 2600. The rating difference of 35 gave Portish an expected score of 0.55. The expected score is summed for each opponent, giving Portisch a total expected score of 9.66. Then the formula is:
So 2635+10×(10.5–9.66)=2643.4, Portisch's new rating .
The example of Portisch with K=10, with the sum of the rating differences being 1620 is:
The USCF used a modification of this system to calculate ratings after individual games of correspondence chess
, with a K=32 and C=200.
and some online playing sites.
used its own system in the 1970s. Now it uses the Elo system.
. It is based on computer analysis of a large database of games and is intended to be more accurate than the Elo system.
Chess
Chess is a two-player board game played on a chessboard, a square-checkered board with 64 squares arranged in an eight-by-eight grid. It is one of the world's most popular games, played by millions of people worldwide at home, in clubs, online, by correspondence, and in tournaments.Each player...
to calculate an estimate of the strength of the player, based on his performance versus other players. They are used by organizations such as FIDE, the US Chess Federation (USCF), International Correspondence Chess Federation
International Correspondence Chess Federation
International Correspondence Chess Federation was founded in 1951 as a new appearance of the ICCA , which was founded in 1945, as successor of the IFSB , founded in 1928....
, and the English Chess Federation
English Chess Federation
The English Chess Federation is the governing chess organisation in England and is affiliated to FIDE. The ECF was formed in 2004 and was effectively a re-constitution of the extant governing body, the British Chess Federation , an organisation founded in 1904...
. Most of the systems are used to recalculate ratings after a tournament or match but some are used to recalculate ratings after individual games. In almost all systems a higher number indicates a stronger player. In general, a player's rating goes up if he performs better than expected and down if he performs worse than expected. The magnitude of the change depends on the rating of his opponents. The Elo rating system
Elo rating system
The Elo rating system is a method for calculating the relative skill levels of players in two-player games such as chess. It is named after its creator Arpad Elo, a Hungarian-born American physics professor....
is currently the most widely-used.
The first modern rating system was used by the Correspondence Chess League of America in 1939. Soviet player Andrey Khachatoruv proposed a similar system in 1946. The first one that made an impact on international chess was the Ingo system in 1948. The USCF adopted the Harkness system in 1950. Shortly after, the British Chess Federation started using a system devised by Richard W. B. Clarke
Richard W. B. Clarke
Sir Richard William Barnes Clarke, KCB, OBE was a British civil servant. He was educated at Christ's Hospital, London and Clare College, Cambridge; he was sixth wrangler in 1931...
. The USCF switched to the Elo rating system
Elo rating system
The Elo rating system is a method for calculating the relative skill levels of players in two-player games such as chess. It is named after its creator Arpad Elo, a Hungarian-born American physics professor....
in 1960, which was adopted by FIDE in 1970 .
Ingo system
The Ingo system was designed by Anton Hoesslinger and published in 1948. It was used by the West German Chess Federation from 1948 until 1992, when it was replaced by an Elo-based system, Deutsche WertungszahlDeutsche Wertungszahl
The Deutsche Wertungszahl is an evaluation number in chess to compare the playing performance of individual players. It is a chess rating system used in Germany. A higher rating number corresponds to a stronger player...
. It influenced some other rating systems. This is a simple system where a player's new rating is the average rating of his competition minus one point for each percentage point above 50 obtained in the tournament. Unlike most other systems, lower numbers indicate better performance .
Harkness system
The Harkness System was invented by Kenneth HarknessKenneth Harkness
Kenneth Harkness was a chess organizer. He is the creator of the Harkness rating system.-Life and career:...
, who published it in 1956. It was used by the USCF from 1950 to 1960 and by some other organizations.
When a player competes in a tournament, the average rating of his competition is calculated. If the player scores 50% he receives the average competition rating as his performance rating. If he scores more than 50% his new rating is the competition average plus 10 points for each percentage point above 50. If he scores less than 50% his new rating is the competition average minus 10 points for each percentage point below 50 .
| Category | Rating range |
|---|---|
| Grandmaster | 2600 and up |
| Senior master | 2400–2599 |
| Master | 2200–2399 |
| Expert | 2000–2199 |
| Class A | 1800–1999 |
| Class B | 1600–1799 |
| Class C | under 1600 |
Example
A player with a rating of 1600 plays in an eleven-round tournament and scores 2½–8½ (22.7%) against competition with an average rating of 1850. This is 27.3% below 50%, so his new rating is 1850 – (10 × 27.3) = 1577 .English Chess Federation system
The English Chess FederationEnglish Chess Federation
The English Chess Federation is the governing chess organisation in England and is affiliated to FIDE. The ECF was formed in 2004 and was effectively a re-constitution of the extant governing body, the British Chess Federation , an organisation founded in 1904...
(formerly British Chess Federation) Grading System was devised by Richard W. B. Clarke
Richard W. B. Clarke
Sir Richard William Barnes Clarke, KCB, OBE was a British civil servant. He was educated at Christ's Hospital, London and Clare College, Cambridge; he was sixth wrangler in 1931...
and first published in 1958. Points are scored for every game played in a registered competition (generally, English congresses, local and county leagues, and other team events). A player's grade is calculated by taking the opponent's grade and adding 50 points for a win, subtracting 50 points for a loss, and taking the opponent's grade as it stands for a draw. For grading purposes it is assumed that the opponent's grade is never more than 40 points above or below one's own. The ECF grades approximately 200,000 games a year. The grading season runs from 1 June to 31 May. An ECF grade can be approximated to an Elo rating by multiplying by 8 and adding 600. An ECF grade of 100 is approximately 1400 Elo, while 200 ECF equals 2200 Elo.
Elo rating system
The Elo system was invented by Arpad EloÁrpád Élo
Arpad Emrick Elo is the creator of the Elo rating system for two-player games such as chess. Born in Egyházaskesző, Austro-Hungarian Empire, he moved to the United States with his parents as a child in 1913.Elo was a professor of physics at Marquette University in Milwaukee, Wisconsin. He was...
and is the most common system. It is used by FIDE and other organizations.
FIDE classifies tournaments into categories according to the average rating of the players. Each category is 25 rating points wide. Category 1 is for an average rating of 2251 to 2275, category 2 is 2276 to 2300, etc. For women's tournaments, the categories are 200 rating points lower, so an Category 1 is an average rating of 2051 to 2075, etc.
| Rating range | Category |
|---|---|
| 2600+ | World Championship World Chess Championship The World Chess Championship is played to determine the World Champion in the board game chess. Men and women of any age are eligible to contest this title.... contenders |
| 2400–2600 | most Grandmasters (GM) and International Masters (IM) |
| 2300–2400 | FIDE Masters (FM) |
| 2200–2300 | FIDE Candidate Masters (CM), most national masters |
| 2000–2200 | candidate masters, experts (USA) |
| 1800–2000 | Class A, category 1 |
| 1600–1800 | Class B, category 2 |
| 1400–1600 | Class C, category 3 |
| 1200–1400 | Class D, category 4 |
| below 1200 | novices |
The USCF uses a modification of the Elo system, where the K factor varies and there are bonus points for superior performance in a tournament. The USCF classifies players according to their rating . USCF ratings are generally 50 to 100 points higher than the FIDE equivalents .
| Category | Rating range |
|---|---|
| Senior master | 2400 and up |
| National master | 2200–2399 |
| Expert | 2000–2199 |
| Class A | 1800–1999 |
| Class B | 1600–1799 |
| Class C | 1400–1599 |
| Class D | 1200–1399 |
| Class E | 1000–1199 |
| Class F | 800–999 |
| Class G | 600–799 |
| Class H | 400–599 |
| Class I | 200–399 |
| Class J | 100–199 |
Example
Elo gives an example of calculating the rating of Lajos PortischLajos Portisch
Lajos Portisch is a Hungarian chess Grandmaster, whose positional style earned him the nickname, the "Hungarian Botvinnik"...
, a 2635-rated player, in an actual tournament of 16 players, and scored 10½ points. First the difference in rating is calculated for each other player, subtracting the other player's rating from Portisch's rating. Then the expected score against each player is determined from a table, based on this rating difference. For instance, one opponent was Vlastimil Hort
Vlastimil Hort
Vlastimil Hort is a chess Grandmaster of Czech nationality. During the 1960s and 1970s he was one of the world's strongest players and reached the Candidates stage of competition for the world chess championship, but was never able to compete for the actual title.Hort was born in Kladno,...
, who was rated at 2600. The rating difference of 35 gave Portish an expected score of 0.55. The expected score is summed for each opponent, giving Portisch a total expected score of 9.66. Then the formula is:
- new rating = old rating + K×(W-We), where K=10, W=actual score, and We=expected score.
So 2635+10×(10.5–9.66)=2643.4, Portisch's new rating .
Linear approximation
Elo devised a linear approximation to his full system. With that method, a player's new rating is his old rating plus K×(W-L)/2 plus K/(4C) times the sum of Di, where C=200, K=32, each Di is the opponent's rating minus the player's rating, W is the number of wins, and L is the number of losses .The example of Portisch with K=10, with the sum of the rating differences being 1620 is:
- 2635+10*(10.5-4.5)/2-(10/800)×1620=2644.75 .
The USCF used a modification of this system to calculate ratings after individual games of correspondence chess
Correspondence chess
Correspondence chess is chess played by various forms of long-distance correspondence, usually through a correspondence chess server, through email or by the postal system; less common methods which have been employed include fax and homing pigeon...
, with a K=32 and C=200.
Glicko rating system
The Glicko system was invented by Mark E. Glickman as an improvement of the Elo system. The Glicko-2 system is a refinement and is used by the Australian Chess FederationAustralian Chess Federation
The Australian Chess Federation is dedicated to promoting the game of chess in Australia, and is a member of FIDE, the world chess federation...
and some online playing sites.
USA ICCF system
The ICCF U.S.A.ICCF U.S.A.
ICCF U.S.A. is a member of the International Correspondence Chess Association for the territory of the United States.- History :The Correspondence Chess League of America was the first American chess club to become an ICCF affiliate. It was created in 1917 as a merger of four clubs, one of which...
used its own system in the 1970s. Now it uses the Elo system.
Deutsche Wertungszahl
The Deutsche Wertungszahl system replaced the Ingo system in Germany.Chessmetrics
The Chessmetrics system was invented by Jeff SonasJeff Sonas
Jeff Sonas is known as a statistical chess analyst who invented the Chessmetrics system for rating chess players, which is intended as an improvement on the Elo rating system. He is the founder and proprietor of the Chessmetrics.com website, which gives Sonas' calculations of the ratings of current...
. It is based on computer analysis of a large database of games and is intended to be more accurate than the Elo system.
History
- 1933 – The Correspondence Chess League of America (now ICCF U.S.A.ICCF U.S.A.ICCF U.S.A. is a member of the International Correspondence Chess Association for the territory of the United States.- History :The Correspondence Chess League of America was the first American chess club to become an ICCF affiliate. It was created in 1917 as a merger of four clubs, one of which...
) is the first national organization to use a numerical rating system. It chooses the Short system which clubs on the west coast of the US had used. In 1934 the CCLA switched to the Walt James Percentage System but in 1940 returned to a point system designed by Kenneth Williams. - 1942 – Chess ReviewChess ReviewChess Review is a U.S. chess magazine that was published from January 1933 until October 1969 . Until April 1941 it was called The Chess Review. Published in New York, it began on a schedule of at least ten issues a year but later became a monthly...
uses the Harkness system, an improvement of the Williams system. - 1944 – The CCLA changes to an improved version of the Williams system devised by William Wilcock. A slight change to the system was made in 1949.
- 1946 – The USSR Chess FederationRussian Chess FederationThe Russian Chess Federation is the officially recognized arm of the FIDE in Russia....
uses a non-numerical system to classify players. - 1948 – The Ingo system is published and used by the West German Chess Federation.
- 1949 – The Harkness system is submitted to the USCF. The British Chess Federation adopts it later and uses it at least as late as 1967 .
- 1950 – The USCF starts using the Harkness system and publishes its first rating list in the November issue of Chess LifeChess LifeChess Life is a monthly chess magazine published in the United States. The official publication of the United States Chess Federation , it reaches more than a quarter of a million readers every month. A subscription to Chess Life is one of the benefits of Full Adult, Youth, or Life membership in...
. Reuben FineReuben FineReuben Fine was one of the strongest chess players in the world from the early 1930s through the 1940s, an International Grandmaster, psychologist, university professor, and author of many books on both chess and psychology.Fine won five medals in three chess Olympiads. Fine won the U.S...
is first with a rating of 2817 and Sammy Reshevsky is second with 2770 . - 1959 – The USCF names Arpad Elo the head of a committee to examine all rating systems and make recommendations.
- 1961 – Elo develops his system and it is used by the USCF . It is published in the June 1961 issue of Chess Life .
- 1970 – FIDE starts using the Elo system. Bobby FischerBobby FischerRobert James "Bobby" Fischer was an American chess Grandmaster and the 11th World Chess Champion. He is widely considered one of the greatest chess players of all time. Fischer was also a best-selling chess author...
is at the top of the list . - 1978 – Elo's book (The Rating of Chessplayers, Past and Present) on his rating system is published.
- 1993 – Deutsche WertungszahlDeutsche WertungszahlThe Deutsche Wertungszahl is an evaluation number in chess to compare the playing performance of individual players. It is a chess rating system used in Germany. A higher rating number corresponds to a stronger player...
replaces the Ingo system in Germany. - 2001 – the Glicko systemGlicko rating systemThe Glicko rating system and the Glicko-2 rating system are chess rating systems similar to the Elo rating system: a method for assessing a player's strength in games of skill such as chess. It was invented by Mark Glickman as an improvement of the Elo rating system...
is published. - 2005 – Chessmetrics is published by Jeff Sonas.
See also
- Chess engine rating lists
- Sports rating systemSports rating systemA sports rating system is a system that analyzes the results of sports competitions to provide objective ratings for each team or player. Rankings are then derived by sorting each team's ratings and assigning an ordinal rank to each team starting with the highest rated team earning the #1 rank...
- List of FIDE chess world number ones