The Expected Result for chess tournament is calculated individually as the sum of all expected results with each opponent. The FIDE rule of 350 points has impact on the Expected Result. Before, FIDE calculated the Expected Result in another way.
Example 1: (the FIDE rule of 350 points not applied): Player A rated 2200, played 2 games against Player B rated 2300 and Player C rated 1950. The Expected Result for player A is therefore calculated as this:
Expected Result 1 (rating difference 100, Player A weaker) = 0.36
Expected Result 2 (rating difference 250, Player A stronger) = 0.81
Expected Result for Player A (for 2 games) = 0.36 + 0.81 = 1.17
Example 2: (the FIDE rule of 350 points applied): Player A rated 2200, played 2 games against Player B rated 2600 and Player C rated 1950. The Expected Result for player A is therefore calculated as this:
Expected Result 1 (rating difference more than 350 (2600-2200=400), Player A weaker) = 0.11
Expected Result 2 (rating difference 250, Player A stronger) = 0.81
Expected Result for Player A (for 2 games) = 0.11 + 0.81 = 0.92
Example 3: (the FIDE rule of 350 points applied): Player A rated 2200, played 2 games against Player B rated 2300 and Player C rated 1600. The Expected Result for player A is therefore calculated as this:
Expected Result 1 (rating difference 100, Player A weaker) = 0.36
Expected Result 2 (rating difference more than 350 (2200-1600=600), Player A stronger) = 0.89
Expected Result for Player A (for 2 games) = 0.36 + 0.89 = 1.25
Calculating New Rating and K-factor
New Rating = Old Rating + Rating Change ... or ...
New Rating = Old Rating + K-factor * (Result - Expected Result)
The K-factor is assigned, and it may range from 10 to 45 for different chess organizations. FIDE uses the following rules to the K-factor:
• The K-factor is 25 for players new to the rating list, until they have completed events with a total of at least 30 games;
• The K-factor is 15 for players with a rating under 2400;
• The K-factor is 10 once the player has reached 2400 and been registered for at least 30 games. Thereafter it remains permanently at 10, even if the player’s rating is under 2400 at a later stage.
Calculating Rating Increase/Decrease
Rating Increase/Decrease is very important for your Rating Change. If your Rating Increase is 0.15 and your K-factor 20, then your Rating Change will be 3. If your Rating Decrease is - 0.20 and your K-factor 10, then your Rating Change will be - 2.
Rating Increase/Decrease is actually not called like this. Officially, it is called in the FIDE Players' Database as "change". But let's name it Rating Increase/Decrease for better understanding. It is an absolute value which can be plus, minus, or zero and is calculated as this:
Rating Increase/Decrease = Result - Expected Result
Example 1: Player A in a 9-game chess tournament scored 5.5 and his Expected Result was 4.0. The Rating Increase/Decrease for player A is therefore calculated as this:
Rating Increase = 5.5 - 4.0 = 1.5
Example 2: Player A in a 5-game chess event scored 1.5 and his Expected Result was 3.5. The Rating Increase/Decrease for player A is therefore calculated as this:
Rating Decrease = 1.5 - 3.5 = - 2.0
Example 3: Player A in a 9-game chess tournament scored 4.5 and his Expected Result was 4.5. The Rating Increase/Decrease for player A is therefore calculated as this:
Rating Increase/Decrease = 4.5 - 4.5 = 0
Calculating Performance Rating
Performance Rating = Opponents' Average + Performance Change
Performance Change is based on the Performance Ratio. If a player scored 9 in 9 games, his or her Performance Ratio is 1.00 and Performance Change + 677. If he scores 4.5 in 9 games, it is correspondingly 0.50 and Performance Change will be 0. The needed value is taken from the Table of Performance Change.
Please notice that your Performance Rating does not depend on your own rating but does depend on your Opponents' Average and "how you performed" (Performance Change). Performance Rating is very important for getting the Grandmaster and International Master Norms.
In some Chess Organizations (but not in FIDE), the Performance Rating is calculated with "the algorithm of 400": If you win, add 400 to the opponent's rating; if lose, subtract 400, if you make a draw, no change. Then find the average.
Calculating Grandmaster and International Master Norms
The Grandmaster or International Master Norm is the minimum score at which the player may get the norm. The Grandmaster or International Master Norm is possible under the following 2 (two) conditions:
1. The player must meet the FIDE norm requirements.
2. The player's score must provide, at least, the minimum Performance Rating needed for the norm.
The following is some of the FIDE norm requirements:
• At minimum, 9 games played;
• At least 50% of the opponents must be titled;
• For a GM norm, at least 3 of the opponents must be GMs;
• Maximum 22% of the opponents can be unrated.
The following minimum Performance Rating is needed:
• 2601 for the Grandmaster Norm;
• 2451 for the International Master Norm;
• 2401 for the Woman Grandmaster Norm;
• 2251 for the Woman International Master Norm.
You can get the International Master Title if you have 3 (three) 9-game-tournament's International Master Norms, and if FIDE recalculated your current rating at 2400 even once. You can get the Grandmaster Title if you have 3 (three) 9-game-tournament's Grandmaster Norms, and if FIDE recalculated your current rating at 2500 even once.
There is no need to have any Norms for getting the third Title in FIDE - the FIDE Master Title. You just need to "hit" the specific current rating as defined by FIDE. For more details on awarding the Titles of Grandmaster, Woman Grandmaster, International Master, Woman International Master, and FIDE Master, please see the FIDE Titles.
Calculating Opponents' Average
There is no need to explain Opponents' Average; it is quite understandable. The only thing you must remember is that the FIDE rule of 350 points in rating difference has impact on Opponents' Average too as shown below.
If you are rated 2350, and 2 your opponents 1800 each, the FIDE average of your opponents will be 2000, but not 1800 as expected. If you are rated 2150, and 2 your opponents 2600 each, the FIDE average of your opponents will be 2500, but not 2600 as expected.
Conclusion
Elegant and beautiful, this is the Elo rating system which was named after its creator Arpad Emrick Elo who had improved the original Harkness' rating system. Nowadays the Chess Organizations usually use their own interpretation of the Elo system...
Elo rating is often used to mean a player’s chess rating as calculated by FIDE. However, other Chess Organizations, National Federations, Internet Servers, and so one have adopted Elo’s and Harkness’ general ideas, but added their own rules to them.
For example, the same chess player at the same time can be rated 2500 by FIDE, 2600 by USCF (The United States Chess Federation), and 3000 by ICC (The Internet Chess Club) because of a different approach in Elo calculation.
Some Chess Federations have Rating Scale Categories for the chess players. It is a division of the chess players by their ratings but not by their real titles. Please click on the following links for reference on the FIDE Rating Scale Categories or USCF Rating Scale Categories.
At the end of each tournament, the organizers calculate Elo results for each participant and prepare so-called Final Standings Table. It is line by line Table which includes the chess players' names, their current ratings at the start day, and Elo results for the tournament.
The Final Standings Tables are submitted to FIDE. The latter recalculates Elo results for each chess player, makes corrections if any mistake, and prepare the FIDE Players' Database which is updated quarterly and is available online.
If you are an unrated chess player, the following link will briefly explain you how to get initial rating in FIDE. Once you have an initial rating, you may officially step by step move up in the ancient, noble, and beautiful game of chess that makes people think...
On the next pages of www.chesselo.com, you can find Chess Players Top Elo, valuable links on Chess Elo in FIDE (FIDE Players' Database, FIDE Look-up Tables, Norm requirements, original information on the FIDE rating system, licensed Elo Calculator for FIDE), and Chess Search.
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