What is Elo? An explanation of competitive gaming's hidden rating system
Elo is a huge part of competitive gaming—and many people aren't aware that it even exists.
It's hidden inside of a game's ranked mode. When you win or lose a game, the system changes your ranking to match you up against a player of equal skill level. The system is used to deliver fair and balanced matchups for all players, giving everyone a metric to judge their performances against other competitors.
In short, Elo is a method of calculating the skill level of players in a competitive environment, and it's present in most competitive video games. The story of how Elo came to be, however, begins with a decidedly non-digital game.
Origins and meaning
The Elo rating system is named after its creator, Arpad Elo. He was a Hungarian-born professor who taught physics at Marquette University from 1935 to 1965. After retiring from Marquette, he lectured for several years at the University of Wisconsin.
He was a skilled chess player and an active participant of the United States Chess Federation (USCF), which is the governing body for chess competition in the United States. He was also known as the strongest chess player in Milwaukee in the 1930s.
Before the Elo rating system was invented, the USCF used a system created by Kenneth Harkness, a Scottish-born business manager, called the Harkness Rating System. The system tracked an individual player's progress in a game like chess through their overall wins and losses.
The system was successful at the time, but slowly gave rise to ratings that many players thought were confusing and inaccurate. In theory, a player could enter multiple low-level tournaments and rack up a lot of wins to improve their rating, whereas players who only played in high-level tournaments would have a lower rating than those who beat a lot of low-skilled players.
Professor Elo noticed these inaccuracies and went out to create a new system that would be based on stats, rather than results.
His system looked past a simple win-loss formula and focused more on a player's overall performance. He based his system on a game-by-game basis. If a player won a game, their performance level went up slightly, and if they lost, it went down slightly.
The Elo system proposed a straightforward method of estimating a player's true skill. If a player wins more games than expected, their rating is adjusted upward. And if they lose a lot of matches, their rating will fall. It's a simple method that makes it easier to put players of similar skill level against one another.
The system was implemented by the USCF in 1960 and it worked so well that the World Chess Federation adopted it in 1970.
How do games use the Elo method?
As competitive gaming bloomed, Elo's rating system was later adapted to fit a multitude of different online competitive games and traditional sports. The way in which Elo is used, however, depends on the game.
Each competitive game ranging from League of Legends' ranked mode to Counter Strike's ranked lobby uses a form of Elo in some way to match players of similar skill level against one another.
Counter-Strike, for example, keeps track of how many rounds a player has won rather than the overall outcome of the game. This modified system uses simple calculations to add things like handicaps, which takes into account how well a player performs against higher or lower ranked players if they're playing with teammates of a different rank.
PlayerUnknown's BattleGrounds still uses the original Elo system for its ranked mode. As you win more games, your ranking rises slowly, and if you lose games, it decreases slightly. The competitive leaderboards are then broken up into different game modes, which means players are being judged by each game mode.
League of Legends, on the other hand, used the Elo rating system prior to season three. Riot Games then created its own method based on the Elo system called the League system.
This system still matches players of a similar skill level against one another, but it also breaks all players into seven distinct tiers. Each tier from Bronze to Challenger is broken up into five divisions, which means that players need to continuously win games to climb up the rankings.