Japan Chess Federation Rating Regulations

1. Purpose of National Ratings

(1) To appropriately quantify the strength of players participating in national rated games (hereinafter referred to as “rated games”).
(2) To use national ratings as reference materials for determining starting rankings in tournaments, awarding national titles, and selecting representative players.

2. Types of National Ratings

(1) The Japan Chess Federation (hereinafter referred to as “the Federation”) issues and calculates two types of ratings: Standard and Rapid.
(2) Games where the time control per player at the 60-move mark (Note 1) is 45 minutes or more are classified as Standard. Games with time control between 10 minutes and less than 45 minutes are classified as Rapid. Games under 10 minutes are not included in the rating calculation.

3. Games Subject to Calculation

(1) National ratings reflect the results of games in rated games.
(2) There are two types of rated games: tournaments and regular meetings. Tournaments refer to events that use formats like the Swiss system or round-robin to determine rankings. Regular meetings refer to other types of events.
(3) Rated games may only be hosted by the Federation, registered clubs, or collegiate chess federation-affiliated circles, and must be run fairly by Federation annual members.
(4) Organizers must apply to host rated games to the Federation at least five days prior to the event. They must also clearly state in the event details that it is a rated game and specify the type of rating.
(5) Only games between Federation annual members with valid memberships at the time of the match will be eligible for rating calculation.
(6) In principle, the Federation will publish a new rating list on the 1st of each month, reflecting games reported between the 21st of the month before last and the 20th of the previous month (Note 2).
(7) Games reported more than three months (Note 3) after the final day of the rated game may not be eligible for calculation.
(8) Games deemed inappropriate as rated games by the Federation, such as those not fairly conducted, may not be included in the rating calculation.

4. Reporting Format

(1) Organizers must report all games from hosted rated games to the Federation.
(2) Results should be reported within the reporting period specified in 3(7), and the reporter must be either the event organizer or a Federation annual member authorized by the organizer.
(3) The result report must include the following details:
　　a) Event name, schedule, organizer, time control, type of rating
　　b) Names of participants (Note 4), Federation ID
　　c) Names of the players with white and black pieces, match results
　　d) Number of non-member participants
(4) The latest version of the “Rating Report Form” provided by the Federation must be used for reporting. However, if pairing software Swiss-Manager is used, uploading the results to Chess-Results.com and notifying the Federation of the URL will suffice as result reporting.
(5) Reports must be submitted via email to japanchess.rating@gmail.com.

5. Rating Calculation Method

(1) The rating change value C for each game is calculated using the following formula:
C = (R-PD)*K

R is the player’s score, where a win equals 1, a draw equals 0.5, and a loss equals 0.
PD is the expected score based on the rating difference between players, as shown in Table 1. Refer to column H if the player’s rating is higher than their opponent’s, or column L if lower. If the rating difference exceeds 400, it is treated as 400.
K is the rating coefficient, usually set at 20.
- It is set at 40 if the player has fewer than 30 rated games.
- It is set at 40 if the player is under 19 years old and has never reached a rating of 2000. Age is determined as of January 1 of that year.
- It is set at 10 if the player has ever reached a rating of 2400.
C = 0 for forfeited wins or losses, or games against unrated (UR) opponents, and such games are not counted toward the total number of games.

(2) The total of C for all games within the reporting period is rounded and added to the player’s previous rating to calculate the new rating.
(3) The minimum national rating is 1000. If the calculated result falls below 1000, the rating will remain 1000.

6. Determination of Initial Rating

(1) If a player has a FIDE rating at the time of their first membership with the Federation, it will be adopted. FIDE Standard ratings are adopted as national Standard ratings, and FIDE Rapid ratings are adopted as national Rapid ratings.
(2) If either the Standard or Rapid rating has not been determined, the undetermined rating will adopt the determined rating when it is first calculated.
(3) Players whose ratings are not determined by (1) or (2) are considered UR. When their total number of games against rated opponents in the past two years reaches six or more within a reporting period, their initial rating will be calculated based on performance ratings from those games. However, if the results of the games are all wins or all losses, performance rating calculation will be delayed until the player does not achieve all wins or all losses in a reporting period.
(4) Performance rating PR is calculated using the following formula:
PR = RA+dp

RA is the average rating of the opponents.
dp is given according to the score percentage p in the games, as shown in Table 2.

7. Other Provisions

(1) Organizers of rated games must take the utmost care in handling personal information.
(2) Matters not covered by these regulations will be referred to FIDE’s rating regulations, and the Federation’s Rating Department will discuss and decide on how to handle such matters.
(3) If an error in the published ratings is pointed out, the Federation will recalculate and publish a corrected rating list. However, recalculation will not be performed for ratings published more than 90 days before the date the error was reported.
(4) Amendments to these regulations are subject to approval by the Federation’s Board of Directors.

Issued: February 5, 2019
Revised: May 11, 2019 (Effective June 1, 2019)
Revised: August 31, 2019 (Effective September 1, 2019)
Revised: March 31, 2020 (Effective May 1, 2020)
Revised: January 31, 2021 (Effective February 1, 2021)
Revised: August 31, 2022 (Effective September 1, 2022)
Revised: August 1, 2023 (Effective August 1, 2023)
Revised: September 27, 2024 (Effective October 1, 2024)

Table 1: Rating Difference and Expected Score

Table 2: Score Percentage and dp

Note 1: In a game with a time control of 45 minutes + 30 seconds/move, the “time control at the 60-move mark” is calculated as 45 + 0.5 * 60 = 75 minutes.
Note 2: For example, the rating list published on March 1 will include games reported between January 21 and February 20.
Note 3: If the final day of a rated game is January 15, the deadline for reporting would be April 15.
Note 4: Names reported must be in Roman characters, in the format of surname followed by first name, without a comma between them.
Note 5: In the event of any discrepancies between the Japanese and English versions, the Japanese version shall prevail.