Your rating is a single number that estimates how strong you are. It goes up when you win, down when you lose, and the exact amount depends on who you played. This page explains the whole system — the real formula our server uses, nothing hidden.
ChessDada uses the Elo system — the same family of maths used by FIDE for official world rankings, invented by physicist Arpad Elo. The idea behind it is simple: before a game starts, the rating difference between the two players predicts how likely each one is to win. After the game, we compare what actually happened with what was predicted. A surprise moves the ratings a lot; an expected result barely moves them at all.
The server works out your expected score, a number between 0 and 1. Think of it as "what fraction of this game should you win on average?"
The important consequence: every 400 rating points means roughly 10 times more likely to win. Here is what the prediction looks like in practice for the stronger player:
| Rating gap | Stronger player is expected to score | In plain words |
|---|---|---|
| 0 | 50% | A coin flip |
| 50 | 57% | Slight edge |
| 100 | 64% | Clear favourite |
| 200 | 76% | Strong favourite |
| 400 | 91% | Should win nine out of ten |
| 800 | 99% | An upset would be big news |
Your actual score is 1 for a win, 0.5 for a draw and 0 for a loss. The change to your rating is the gap between reality and prediction, multiplied by a number called the K-factor:
The result is rounded to the nearest whole point.
K controls how much a single game is allowed to move you. A brand new account knows nothing about your real strength, so early games are given more weight:
| Your situation | K-factor | Effect |
|---|---|---|
| First 20 games (provisional) | 40 | Rating moves quickly to find your level |
| After 20 games (established) | 32 | Rating becomes steadier |
Until you have completed 20 rated games, your rating is shown with a small question mark, like 1247?. It means "provisional" — the number is still a rough guess, not a settled rating. It is not a penalty, and nothing is locked. Once you pass 20 games the mark disappears on its own.
These are calculated with the exact same formula the server runs.
You are 1200 and provisional (K = 40). Your opponent is 1400 and established (K = 32). You win.
Notice the two numbers are not identical. That is normal and correct: you were still on the faster provisional K-factor, so the same game moved you further than it moved your opponent.
Same two players, but this time the 1400 wins as expected.
This is the heart of Elo: beating people far below you is almost worthless, and losing to them is expensive. The way to climb is to play opponents near or above your own level.
Two players both on 1200 draw. Each was expected to score 0.5 and each actually scored 0.5, so the change is 0 for both. A draw against a much stronger player, however, still gains you points — you beat the prediction.
| Situation | Rating changes? |
|---|---|
| Normal finish — checkmate, stalemate, draw | Yes |
| A player resigns | Yes |
| A player runs out of time (flag falls) | Yes |
| A player leaves the table during a live game | Yes — counted as a loss |
| A player disconnects and does not return within 2 minutes | Yes — counted as a loss |
| Any game in the Casual Play room | No — always unrated |
| A table that closes before any real moves were played | No |
| Games against the computer, puzzles, analysis board | No |
Once a real game is under way, closing the tab, pressing Exit Table or standing up is treated exactly like resigning. This rule exists to protect the player who stayed: without it, anyone losing a game could simply walk away and keep their rating. If you genuinely need to leave, resign properly — the result is the same for you, and fair to your opponent. A short network drop is not a loss: you get a 2 minute grace period to reconnect and continue.
Use the Casual Play room. Nothing there touches your rating, wins, losses or draws — the game is still saved so you can replay it later, but the score stays exactly where it was. It is the right room for testing an opening, teaching a friend, or just playing for fun.
Next to each player name in the lobby and room lists there is a coloured dot. It is a quick visual band, nothing more — the number itself is what counts.
| Colour | Rating | Typical player |
|---|---|---|
| Green | Below 1200 | Learning the game, building the basics |
| Blue | 1200 – 1499 | Solid club beginner, knows the tactics |
| Purple | 1500 – 1799 | Intermediate, plans ahead and punishes mistakes |
| Orange | 1800 – 2099 | Advanced, strong positional understanding |
| Red | 2100 and above | Expert level on ChessDada |
Remember that an online rating is only meaningful inside the pool it was earned in. A ChessDada rating is not the same thing as a FIDE rating, and comparing numbers across different websites rarely works — every site has a different mix of players and a different starting point.
Because the two of you may be on different K-factors. A provisional player (first 20 games) moves by 40 per unit of surprise, an established player by 32. The numbers are meant to be independent, not mirrored.
Almost certainly not. Losing to an opponent rated far below you is the single most expensive result in Elo, because the system predicted you would win comfortably. Check the rating of the player you lost to — and remember the prediction is made from the ratings before the game started.
Yes. Guest accounts are rated exactly like registered ones and start at 1200. The system does not care whether the account has an email attached, only what its rating is.
No. Bullet, Blitz, Rapid and Classical all feed into one single rating. That keeps things simple, but it is worth knowing: if you are strong at Classical and weak at Bullet, your number lands somewhere in between.
No. There is a hard floor at 100. No sequence of losses can push you below it.
Yes, and more than people expect. A draw against a much stronger opponent is a genuine gain, because you scored above the prediction. A draw against a much weaker opponent costs you points for the same reason.
Play a rated game Elo explained in depth
Further reading: What is a good chess rating? · The Elo rating system explained · All articles