Fide Rating Calculator

FIDE Rating Calculator

Use this calculator to estimate your new FIDE rating after a single game, based on your current rating, your opponent's rating, the game result, and your K-factor.

Understanding FIDE Ratings

The FIDE (Fédération Internationale des Échecs) rating system is a numerical method used to estimate the strength of chess players. It's based on the Elo rating system, developed by Arpad Elo, and is widely used to rank players globally. A higher rating indicates a stronger player.

How FIDE Ratings Are Calculated

FIDE ratings are dynamic, changing after each rated game. The core idea is that if you perform better than expected against an opponent, your rating goes up; if you perform worse, it goes down. The magnitude of the change depends on several factors:

1. Your Current Rating (R_o): Your rating before the game.
2. Opponent's Rating (R_opp): Your opponent's rating before the game.
3. Game Result (S): The outcome of the game (1 for a win, 0.5 for a draw, 0 for a loss).
4. Expected Score (S_e): The probability of you winning the game against your opponent, based on the rating difference. This is calculated using the formula:
   Se = 1 / (1 + 10(-Dr/400))
   where Dr = Ro - Ropp (your rating minus opponent's rating).
5. K-Factor (K): A coefficient that determines how much your rating changes. A higher K-factor means your rating will change more dramatically after a game.

The formula for your new rating (R_n) after a single game is:

Rn = Ro + K * (S - Se)

The K-Factor Explained

The K-factor is crucial as it dictates the volatility of a player's rating. FIDE uses different K-factors based on a player's experience, age, and current rating:

• K=40: This factor is applied to players who have not yet completed 30 rated games. It's also used for all players until their 18th birthday, as long as their rating remains under 2300. This higher K-factor allows new and young players' ratings to adjust more quickly to reflect their true strength.
• K=20: This is the standard K-factor for most established players. It applies to players with a rating below 2400 who have completed at least 30 games.
• K=10: This lower K-factor is for highly rated and experienced players. It applies to players with a rating of 2400 or higher who have completed at least 30 games. This ensures that the ratings of top players are more stable and less prone to large fluctuations from a single game.

If a player with a K-factor of 40 reaches a rating of 2300, their K-factor typically changes to 20.

How to Use the Calculator

1. Your Current FIDE Rating: Enter your FIDE rating before the game.
2. Opponent's FIDE Rating: Enter your opponent's FIDE rating before the game.
3. Game Result: Select whether you won, drew, or lost the game.
4. Your K-Factor: Choose the K-factor that applies to you based on the descriptions provided.
5. Click "Calculate New Rating" to see your estimated new rating and the rating change.

Limitations

This calculator provides an estimate for a single game. Official FIDE rating calculations involve a more complex process, especially when multiple games are played in a tournament, and can include factors like minimum rating floors and specific tournament regulations. However, this tool gives a very good approximation for understanding the impact of a single game on your rating.

Your Current Rating:

Opponent's Rating:

Your K-Factor:

Expected Score (S_e):

Rating Change:

Your Estimated New Rating:

" + formattedNewRating + "