Elo Ratings

Rankings on Siege Ladder use an Elo rating system — the same style of system used in chess (e.g. FIDE, Lichess, Chess.com). It gives you event-agnostic standings for your game system so you can see how you compare to others regardless of which tournaments or events you play in.

For a deeper dive into why we chose Elo and how it works in practice, see the article: I've Built a Chess Rating System for Warhammer.

Screenshot of "Player Rankings" page for the Middle Earth Strategy Battle Game

Leaderboards:

• Middle Earth Strategy Battle Game

How rankings are calculated

Siege Ladder's rankings are modelled on the Chess Elo system. Elo is a mathematical rating system where you gain or lose points after each game based on your result versus what was expected given the two players' ratings. It was designed for chess and works well for any 1v1 game with a clear win/draw/loss outcome.

Core idea

Your rating change depends on:

1. Expected score — How likely you were to win (based on your rating vs your opponent's).
2. Actual score — What actually happened (win = 1, draw = 0.5, loss = 0).
3. K-factor — A cap on how much your rating can move from a single game (see below).

If you beat someone much higher rated, you gain more than if you beat someone much lower rated. If you draw against a stronger player, your rating can still go up because that was better than expected.

Expected score

For each player, the expected score (between 0 and 1) is calculated from the two ratings using the standard Elo formula (the same 400-point scale used in chess):

• ~0.5 — You and your opponent are evenly matched.
• Above 0.5 — You are favoured to win.
• Below 0.5 — You are expected to lose.

A 400-point rating difference corresponds to about 10:1 odds in favour of the higher-rated player, matching the scale used in chess systems.

K-Factor

The K-factor is the maximum amount your rating can change from a single game. Siege Ladder uses progressive K-factors so that:

• New players can move toward their true level quickly.
• Established players' ratings stay more stable.

Starting rating

All new players start at 1,500 Elo. As you play ranked games, your rating moves up or down toward a value that reflects your results.

Ranked vs Casual Games

Not every game on Siege Ladder affects your Elo. When recording a game (or when an event is set up), you choose whether it is Ranked or Casual:

• Ranked — Counts for your Elo. Used for competitive events and matches you want to count toward the ladder.
• Casual — Does not affect your Elo. Used for friendlies, narrative games, or events where only awards (e.g. podium) matter, not ratings.

The default when recording a game is Casual, so only games you explicitly mark as ranked (or that are part of a ranked event) will change your rating.

A player's Elo rating can be found on their Player Profile:

Screenshot of a player's Elo rating history on their Player Profile

The player's profile will detail the full history of their Elo too, showing how they have improved or regressed over time.

Provisional ratings (~)

If you have fewer than 20 ranked games in a game system, your rating is treated as provisional. It is shown with a ~ (e.g. ~1548) to indicate it can still move quite a bit as you play more games. Once you have 20 or more ranked games, the rating is considered more stable and the ~ is no longer shown.