ChessWorld - Rating System FAQ's

In the first 50 games, your rating is provisional and uses the English Chess Federation (ECF) performance-based system. This ensures fair results—for example, you don't gain points from losing to stronger players or lose points by beating much weaker ones.

After 50 games, your rating is calculated using the Elo system. This well-known system is based on both your rating and your opponent's, with adjustments depending on your result:

The formula used is:

r1 + K × (w − 1 / [1 + 10^((r2 − r1) / 400)])

Where:
• r1 is your rating
• r2 is your opponent's rating
• w is your result (0 = loss, 0.5 = draw, 1 = win)
• K is a dynamic factor depending on your rating and other conditions

You can use the ChessWorld Elo calculator to plug in your values and see your new rating.

K-values are typically:
• K = 32 for ratings ≤ 1600
• K = 16 for ratings ≥ 3200
• Otherwise: K = 32 - (r1 − 1600) / 100

Example: If your rating is 2355:
K = 32 - (2355 − 1600) / 100 = 24.45

Special case: When playing a **provisionally rated** opponent, their K-factor is scaled by their number of rated games: (n / 51).

For improvement, focus on playing well rather than rating gains. You may find useful books via our BookFinder page.

Chess is a game of skill with many levels. Even strong players can lose to stronger ones. A rating system helps match players fairly and shows your relative skill compared to others on ChessWorld.

Studying and practice may improve your rating, but results can vary!

Your first 50 games use the ECF system. After that, the Elo rating system is applied, using a classical normal distribution model.

During the provisional period (first 50 games), your rating can swing heavily. To prevent rating abuse, the system uses an ECF “rating roof.”

For example, if your opponent is rated 2700 and you're 1200, they are treated as 1520 in the provisional formula, so you don't gain by losing. The best results come from playing within 320 points of your rating.

After your 50th game, Elo rating applies as usual.

Your rating is based on a small sample size at first, so each result has a big impact. As you play more games, your rating becomes more stable. You can monitor this via the My Stuff ... My Ratings graph.

Yes, ECF 100 is assumed for everyone. Because there are heavy fluctuations in the first few rated games as the rating settles down, it does not matter that the rating is set like this.

Yes, just set your FIDE rating to the equivalent of what your rating is. This is fair because the ratings in the first few games fluctuate heavily anyway. It allows proven strong players to be more quickly identified by the existing stronger players on the site. We may, at our discretion, ask you to provide verification of your rating.

Yes, just set your FIDE rating to less than 1400 when you first start off.

In general, no. However, if you are invited by, or choose, a site Welcomer, any games with that player will be rated.

Subject to certain criteria, ChessWorld does invite all Guest Members to specific Guest Welcoming Tournaments. These Tournaments offer players a chance to play a number of rated games.

By limiting the number of rated games available to Guest Members, it means that the rating system is less prone to distortion by an individual player creating multiple Guest Member accounts, and then using those accounts to deliberately lose games. It would be highly unlikely that someone would want to do this by using multiple Full Member accounts, which would involve a significant financial investment.

Only games longer than 10 half moves count towards ratings.

ChessWorld imposes this limit in an attempt to avoid a situation where players may agree quick losses, draws or wins with each other in an attempt to manipulate their ratings.

By making this strategy more time consuming such abuse is less likely.

Exceptionally, in the extremely rare case where a game is finished by checkmate within the first 10 half moves the rating calculation is invoked. As ChessWorld records all games ending in checkmate we are able to detect potential manipulation. Any such abuse always results in appropriate action being taken in accordance with our Terms and Conditions.

Yes, Full Members can go to their My Stuff ... My Interface page and elect to have the full rating predictor implications on the play page.

Rating in Correspondence Chess can be affected by the fact that you cannot see what outside assistance your opponent is using. There are restrictions regarding acceptable assistance: refer to the section Member Assistance and Fair Play in our Terms and Conditions for further guidance.

Yes, from the Join Games ... Join New Tournaments page, you can choose to play in ‘Class’ tournaments and you will be paired with players with approximately the same ChessWorld rating as you.

Yes. It can happen because your rating reflected on the playing screen is not ‘real time’. For example, if there is a rated result, such as someone resigning against you, and you have not yet refreshed the playing page, the calculations that are shown will be based on your previous rating. You can easily check by refreshing your screen.

Yes, if you have played less than 50 rated games you can change this setting via My Stuff ... My Details. However, once you have completed 50 rated games this descriptor is set automatically by the system and cannot be altered in any other way.

ChessWorld provides a number of different ranges for players of different ability. The playing strength for any player is shown on their homepage in the  Rating  tab. Until a player has completed 50 rated games their classification can be defined, or changed, by visiting the My Stuff ... My Details page. After the initial 50 games have been completed the Playing Strength indicator is based upon the current rating of the player and is therefore controlled solely by the ChessWorld server.

You can check the whole range of ChessWorld classifications in detail by visiting the Rating Classes page. ChessWorld also groups player ratings into the following Categories for certain Tournaments:

   Strength Tournaments:    Beginner – up to 1600,    Intermediate – 1601 – 2400,    Advanced – 2401 and above

   Class Tournaments:    A) less than 1400,    B) 1400 – 1879,    C) 1880 – 2199,    D) 2200 and above.

Every player is recorded on the ChessWorld database in rank order, from the highest rated player to the lowest. It is common practice to consider such a ranking list in simple steps of 1% to avoid having to place many players on common levels. A player placed on the 99th percentile would therefore be a player whose current rating is above 99% of the Members. A player placed on the 50th percentile would be placed in the middle of the Membership in terms of rating. In general every percentile ranking will include a wide number of players.

For a more formal definition of the term, refer to the Percentile article available in Wiki. This page covers the mathematical context and offers relevant references for those who may be interested in exploring the concept further.

You can check your own percentile ranking by visiting your Homepage and opening the   Rating   tab. Your current ranking will be shown in the last row of the top box.

The Rating Graph can be accessed from any homepage via the   Rating   tab, or via My Stuff ... My Rating. The graph shows a basic overview and cannot be configured. It displays results in color:   Win  ,   Draw  ,   Loss  , and   Time Loss  .

It's a helpful tool for checking your or your opponent's playing performance, especially when looking for patterns of wins, losses, or time forfeits. You can view your own or others' graphs to identify streaks or sandbagging tendencies.

You can also analyze trends with overlays like Default + Ratings to compare with opponents' ratings. Hovering over bars gives more details; clicking on the mini-board takes you to the game, with sharing and analysis options.

There is no definitive answer, but most players’ graphs are relatively level. A “normal” graph typically shows a mix of wins and losses, with opponents’ ratings fluctuating above and below your own. Graphs with only wins or only losses over long spans are uncommon.

Yes. Visit My Stuff ... My Rating and select Opponent Statistics. From there, you can click through highlighted links in the My Stats or Opponents Stats sections to explore results in 50-game increments, even beyond 1000 games. Selecting Last 100 games resets the graph to show just the latest 100.

Yes. When you are on the Rating Graph page simply click on the Game link in the lower left corner. This will change to Date and the games will then be displayed in month order...

No! The ChessWorld Rating system is carefully designed to give due credit for the specific format of on-line Chess...

On ChessWorld HERA represents Highest Ever Rating Achieved. This information is provided to enable you to form some idea of the current ability of your opponent.

The HERA value provides an indication of your Opponent's ability at the time that it was achieved. For a more balanced indication...

It is possible that, in certain circumstances, the information displayed in the pop-up may not be up-to-date. If this occurs simply visit your Rating Information page...

When you visit a play page simply roll the mouse over your name. A small pop-up will appear showing a brief summary of your performance...

The Tournament Performance Rating is often used in real-life Tournaments to provide a measure of relative performance against other players in the Tournament.

This information is provided, for completed All-play-All Tournaments, on the cross-table page in three columns, headed TPR, ER Offset and Upset. Further information is available by hovering over the values in the TPR column...

It is important to be aware of the difference between a player Rating and their TPR...

On ChessWorld the value of the TPR is based upon the rating achieved at the end of the game, compared with the enrolment rating, and is independent of the points scored...

A positive TPR, shown in the ER Offset column, suggests playing above rating expectations...

How you make use of TPR is a matter of personal choice...

On ChessWorld an upset occurs when a player beats an opponent with a significantly higher rating. For example, a 1500-rated player beating someone rated 2000 would be considered an upset.

ChessWorld may adjust the margin used to define an Upset from time to time.

You will see this term if you visit My Stuff ... My Rating and click on Opponent Statistics. The page shows Max, Min, Avg, SD stats in blocks of 50 games...

SD stands for Standard Deviation. A small SD (e.g., below 2) implies consistent performance. Larger SDs imply greater variability.

Useful links: Standard Deviation on Wikipedia and Math is Fun explanation.

This allows Members to see how each player was rated at the time of the game and what their current ratings are in brackets.

This context helps evaluate the quality of the performance.