Gradings in Chess

Players in England are given a three digit grading by the English Chess Federation. To be given a grading they have to be registered with the Federation and the results of their matches are then used to calculate their grade. The ECF system has been in use for decades because it is easy to calculate.

The FIDE ( Fédération Internationale des Échecs or World Chess Federation ) system uses a more sophisticated method devised by Prof. Arpad Elo. The resulting grades are known as ELO grades.

The USCF (United States Chess Federation) uses a modification of the Elo system, where there are bonus points for superior performance in a tournament. USCF ratings are generally 50 to 100 points higher than the FIDE equivalents.

What is the grade of an average registered Chess Player?

The ECF average (mean) grade is 134. This figure is calculated from all of the players who are registered with the organisation - both adults and juniors players. It uses data of all of the games they have played, excluding rapidplay games. It therefore represents an average competition standard player - which is pretty good!

A grading of 200 brings you to 'Master' level - or an 'expert' in the USA.

What are the grades used for?

By comparing the grades of two players, one can find the likelyhood of the outcome of their playing one another, the percentage chance who will win.

If the two players were equally matched there would be a 50:50 chance of a win by either player - in fact a good chance of a draw!

If the one player is higher graded, the chance of his winning should be higher.The system of grading intends to result in the outcome that a player graded 10 points higher than his or her opponent would be expected to score 10% better than evens against them - have a 60% chance of winning, and a higher rated player playing against a player of grading difference of 20 points is expected to have a 70% chance of winning etc

A formula is used to calculate that percentage chance.

E (% score) = 50 + ECF_A – ECF_B

The expected percentage score = 50 plus the difference in grades between players A and B.

The ECF system is not defined for players that are more than 40 grading points apart. If one player was graded 40 more than the other, then the expected score between them in a ten game match would be 9-1 (because 50%+40%=90%). This doesn't happen very often in competitive play - players are usually matched with those of a similar grading within competitions..

Conversion of ECF to ELO and USCF grades

The statistical assumptions behind the ECF system and the international FIDE system are different, but it is possible to make an approximate conversion.

ECF x 8 + 650 = ELO

ELO + 100 = USCF