Question 1

What is the ELO rating system?

Accepted Answer

ELO is a method for calculating the relative skill levels of players in two-player games. It was invented by Arpad Elo and is used in chess, Go, and many other competitive games.

Question 2

What is the K-factor?

Accepted Answer

The K-factor controls how much a single result can change your rating. FIDE uses K=40 for new players, K=20 for standard players, and K=10 for players above 2400.

Question 3

What does expected score mean?

Accepted Answer

The expected score is your statistical probability of winning based on the rating difference. A 200-point advantage gives roughly 76% expected score.

Question 4

Why does beating a lower-rated player gain fewer points?

Accepted Answer

The ELO formula adjusts for the expected outcome. Beating someone you were supposed to beat gains fewer points than beating a stronger player.