Elo Rating System - Everything You Need to Know (2023)

Posted at 06:38hin Basics of ChessbySanjana Chandan



An ELO Rating system is a ranking system to measure the skills of players competing at a sport. It is a tool that clarifies where the world’s top chess players rank alongside each other and tells us how well-trained and skilful a chess player is.

In the world of chess, the highest governing body – Federation International des Echecs (FIDE), maintains and updates the rankings of professional chess players based on their performances in registered tournaments. The US has a national chess governing body as well called the United States Chess Federation (USCF).

A chess ranking system is based on a rating mechanism that will generally have a range of 400 for FIDE tournaments and 100 for USCF tournaments to 2000+. In other words, a professional chess competitor will begin with an average chess rating of 400.

Who Created the Elo System?

The Elo system was created by Arpad Elo, a physics professor in the United States and a chess master who worked to improve the way the U.S. Chess Federation measured their players’ skill levels. The Elo rating system was officially adopted by the U.S. Chess Federation in 1960 and by FIDE in 1970.

The modern chess rating system was first introduced in 1939 by the Correspondence Chess League of America. The chess rating system that made headlines on a global scale was the Ingo system in 1948.

How Does The Elo System Work?

This system calculates the probable outcome of one’s games against other players. Usually, a player who is rated 100 points higher than their opponent is expected to win roughly five out of eight games, while a player with a 200-point advantage will presumably win three out of four games.

To help you understand this system better, check out the following table, which consists the Elo scale according to the 1978 standard.

Rating RangeCategory
2700 +Highest level of Grand Masters including World Champions and World Championship contenders
2500 - 2700Grand Masters
2400-2500International Masters and Grand Masters
2300-2400FIDE Masters and International Masters
2200-2300FIDE Candidate Masters and National Masters
2000-2200Candidate Masters
1800-2000Class A, Category 1
1600-1800Class B, Category 2
1400-1600Class C, Category 3
1200-1400Class D, Category 4
Below 1200Novices

A chess ranking system generally ranks players from the time they begin their professional chess career. This rating calculator classifies chess players after each game is played. Lower-rated players can still beat someone who is rated higher than them, and the Elo system calculates the probability of that happening.

Further, the gap in the ratings between two players determines how many points the two players can gain or lose depending on the result of the match. Since a much higher-rated player is expected to win, they do not receive a lot of points for a victory against a player rated much lower. Their opponent also does not lose a significant amount of points for the defeat.

The Math Behind the Elo System

The inventor of the Elo chess ranking system, Arpad Elo, devised a formula to calculate each professional chess player’s rating. He called this formula ‘linear approximation’.

As per the linear approximation of the Elo rating system:

Rnew = Rold + K/2 (W – L + ½ [EiDi/C])

Here, ‘Rold’ and ‘Rnew’ are the earlier and current ratings of the chess player in question. ‘Di’ is the rating of the opponent after subtracting the said player’s rating;

‘L’ happens to be the total number of defeats;

‘W’ is the number of victories;

the values of ‘C’ and ‘K’ are 200 and 32, respectively.

If you want to calculate a chess player’s rating based on the Elo formula, first find out the average chess rating of the opponent player. Once you have that at your disposal, place the number in the formula along with the number of games the player is expected to win in the formula. After completing the calculation, you will have the chess player’s new rating.

Inflation and Deflation

Inflation suggests that the level of playing strength demonstrated by the rated player decreases over time

Deflation means that the level of the rated player is advancing.

For example, if there is inflation, a modern rating of 1300 means less than a historical rating of 1300, while the reverse is true if there is deflation. In a pure Elo system, each game ends in an equal transaction of rating points. Thus, if the winner gains N rating points, the loser will drop by N rating points.

In a study conducted by Sonas on FIDE ratings, where he studied the highest ratings, he acknowledged that changes in the distribution of ratings could have been caused by an increase in the standard of play at the highest levels, but he also continued to look for other causes.

Issues with the Elo System

Sometimes, the Elo rating system may discourage game activity for players who wish to protect their rating

Concerns over players avoiding competitive play to protect their ratings have also been raised in the past few years to avoid their ratings from dropping

In online chess tournaments and matches - engine abuse is a massive obstacle that can manipulate the Elo system.

Why Elo System is Important?

Almost all chess federations and websites around the world use the Elo rating system or a variation of it. This measurement of a player’s strength has become the norm in the chess world and has become the easiest way to assess someone’s level of play.

In addition, the Elo system is a statistical model that operates solely based on the outcomes of the games played. As a result, this measurement is more precise than merely judging a player’s strength based on subjective and arbitrary elements of the game.

Variations of the Elo System

The main variations of the Elo system are:

  • The Ingo System
  • The Harkness System
  • The Glicko Rating System

The Ingo System

The Ingo chess ranking system was designed by Anton Hoesslinger in 1948. The system was in use from the date of its inception until 1992. It was the standard rating mechanism of the West German Chess Federation. The Ingo rating system was a highly influential chess rating system in the earlier decades of the twentieth century.

What made the Ingo system totally different from most other chess rating systems is the fact that here the lower the ratings of a player, the higher ranking that particular was given.

The Harkness System

Another chess ranking system that came up in the mid-twentieth century is the Harkness System. It was devised by Kenneth Harkness at some point before 1950. The USCF, as well as several other international chess organizations, made use of this system from 1950 until 1960.

The Glicko Rating System

This system of chess rating was formulated by Mark E. Glickman. He made changes to the already existing Elo rating system to come up with this new method. The Glicko-2 rating system is considered an improvement to the widely-used Elo rating system. The Australian Chess Federation and several online chess portals, such as Chess.com, use the Glicko-2 rating system to rank chess players.


The Elo rating system has been a boom to the chess world and has provided players across the world with a measurement system that motivates them to compete. Even though the mathematics behind this system may be a little complicated, we hope this article has increased your understanding of the Elo system.

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