Rating Calculator

Rating Rules

Choosing a K-Factor

The K-factor is the development coefficient that determines how strongly each result affects your rating.

This calculator can be used for both national rating calculations and FIDE Elo rating calculations.

Select the K-factor that applies to your country’s rating system.

• Rating below 1600: K = 45
• Rating from 1600 to 1999: K = 30
• Rating from 2000 to 2399: K = 20
• Rating of 2400 or higher: K = 10

National chess federations may use different K-factors and conditions. Always select the K-factor specified by your national rating system.

FIDE Elo Rating Rules

• K = 40 for a player new to the rating list until they have completed events comprising at least 30 rated games.
• K = 20 while a player’s published rating remains below 2400.
• K = 10 once a player’s published rating has reached 2400. The K-factor remains 10 even if the rating later drops below 2400.

• K = 40 until the end of the year of a player’s 18th birthday, provided their rating remains below 2300.

These rules apply when calculating FIDE Standard, Rapid and Blitz ratings.

MICOS™ is the proprietary chess classification system developed by MasterInChess and protected by international copyright law.

You are welcome to use and share MICOS for personal, educational and non-commercial purposes. Commercial use or integration requires permission from MasterInChess.