What is the FIDE Elo formula?

Your new rating = old rating + K × (actual score - expected score). Expected score = 1 / (1 + 10^((opponent rating - your rating) / 400)). Actual score is 1 for a win, 0.5 for a draw, and 0 for a loss.

Which K-factor should I use?

K=40 applies to players in their first 30 rated games or juniors under 18 below 2300. K=20 applies to most established players below 2400. K=10 applies to players who have ever reached 2400 or higher.

Why can I gain points from a draw?

If your opponent is rated significantly higher, the expected score formula assigns you a low probability of winning. A draw (0.5) exceeds that expectation, so you gain rating points even without winning.

Does this calculator match official FIDE results exactly?

For single games it matches the FIDE formula precisely. FIDE applies additional rounding rules across multi-game tournament batches, so totals for large tournaments may differ by 1-2 points.

What is the rating floor?

FIDE sets a floor of 100 — a published rating cannot drop below 100. This calculator shows the theoretical result; the floor is enforced by FIDE during official processing.

Chess Rating Calculator

Name: Chess Rating Calculator
Availability: InStock
Author: Nham Vu

Enter your current rating, your opponent's rating, and the result to calculate your new FIDE Elo rating using the official K-factor formula.

Game Input

K-Factor (Player Status)

Your Current Rating

Opponent Rating

Game Result

Win 1.0 pt Draw 0.5 pt Loss 0.0 pt

Rating Summary

Add a game to see your rating change

Game Log

No games added yet

#	Opponent	Result	Expected	Change

FIDE Elo Formula Reference

Expected score = 1 / (1 + 10^{((Opp − My) / 400)})

Rating change = K × (Actual − Expected)

New rating = Old rating + Rating change

K = 40

New / Junior

K = 20

Standard

K = 10

Elite (2400+)

Summary

Enter your current rating, your opponent's rating, and the result to calculate your new FIDE Elo rating using the official K-factor formula.

How it works

Select your K-factor based on your player status (new, standard, or elite).
Enter your current Elo rating and your opponent's Elo rating.
Select the game result: win, draw, or loss.
Click "Add Game" to include it in a multi-game session or calculate immediately.
The tool computes the expected score using the FIDE probability formula.
Your new rating and point change are displayed instantly for each game and as a session total.

Use cases

Calculate how many Elo points you gain after beating a higher-rated opponent.
Estimate your rating change after a weekend tournament.
Understand how the K-factor affects rating volatility for new vs. established players.
Check if a draw against a much stronger player still helps your rating.
Preview your expected rating before submitting tournament results to FIDE.
Track cumulative rating change across multiple rounds in one session.

Frequently Asked Questions

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Last updated: 2026-05-29 · Reviewed by Nham Vu