eli5 Elo rating system in chess.


I saw a tiktok about some girl who was the daughter of two grand masters. Went deep into a rabbit hole of the world of Chess but I still cannot for the life of me understand this point system ?

In: 30


It’s just maths. It’s named after mathematician Arpad Elo who developed the basic formula that represents the strength of competitors, relative to each other.

Although it is best known for chess, the formula is unrestricted in application and people have even applied to other sports, like football, in an effort to rank teams.

Elo is a ranking system. It assigns a points score to every player, and based on wins/losses and the scores of your opponents, your score goes up and down by some amount based on statistical calculations. It isn’t even a very difficult system, and gives adequate results in estimating the relative strength of players as long as they have played a sufficient number of times for their Elo score to approach their real skill level.

Elo is far from perfect though, and there are actually better, similar systems out there, with the biggest advantage of Elo over those ones being its relative simplicity. Both Glicko 2 and Microsoft’s Trueskill are far better ranking systems based on statistics than Elo.

Its a point system that estimates your skill level.


Beginners start at some point like 1200(starting point can vary), and then gain points when they win and lose points when they lose. So when people talk about chess the first thing they usually say is their rating.


For more details about the rating system; it’s made to consider your opponents skill level as well. If you are 1200 going versus a 1400, you will gain many points for winning, but lose few points for losing. In chess you can also draw/tie so in this case you would gain points for drawing. Oppositely the higher rated player loses more points for losing to a lower rated players, and gains less points for winning versus a lower rating player. The mathematics makes it so that it should not matter if your opponent is higher or lower rating(up to a certain point…), so there’s no “cheating” by only playing high or low rated oppoents.

>some girl who was the daughter of two grand masters

Sounds like Anna Cramling.

Elo is just a way to measure relative strength of 2 players. The interesting part of the system is that it factors in relative strength of the players into the rating change after the game. In other words, if you lose to Magnus Carlsen in chess, you wouldn’t lose very much rating (if at all, because nobody expected you to beat the world champion), but if Carlsen lost to you, he would lose an insane amount of rating, assuming you’re a 1200 rated player