In the first 50 games, your rating is 'provisional' and is calculated by using a standard robust and proven performance rating system - namely the English Chess Federation rating system. This performance-based rating system ensures, for example, that you cannot gain points from losing against a much stronger player, or lose points by winning against a much weaker player.

After the first 50 games, due to the way averaging works, the rating would become frozen eventually, and therefore there is a requirement to use a different method for rating calculation. From your 51st rated game onwards, the 'Elo' rating system is used.

The Elo rating system is the basis of Worldwide standard established FIDE and USCF ratings in Over-the-Board chess. It is a proven method of rating players based on the difference of ratings of the two players, and their score. i.e. 0 for a loss, 1/2 for a draw, 1 for a win. The particular Elo Formula based on 'normal' distribution is:-

Let us say that your rating is r1 and the opponent's rating is r2. Let w have the value of 0 if you lose, 0.5 if you draw, and 1 if you win. The final, and most important, factor is the value of K - this is set according to your rating and special considerations such as if the opponent is provisionally rated or not. The formula may be expressed mathematically as follows:-

                                                                            1
                                    r1 + K * [ w   -    --------------------------------    ]
                                                                1 + 10 ^ ((r2-r1)/400)

You may wish to use the ChessWorld Elo calculator where you can enter your rating, your opponents rating, and the K-factor and then calculate your new rating.

The Elo formula, above, makes use of the classic normal distribution. By default, the K-value is based on your current rating, as follows: -

                K = 32     If your rating is less than or equal to 1600
                K = 16     If your rating is greater or equal to 3200
                For intermediate ratings,     K = 32-(r1-1600)/100

Example: Assume a personal rating of 2355.     Using the formula above: K = 32 - [(2355 - 1600)/100] = 24.45.
However, a much simpler method is to use the ChessWorld ELO calculator and simply enter your current, personal, rating. This will automatically calculate your K rating. Using the value above the K value will be confirmed as 24.45

Special considerations when you play provisionally rated opponents

Because provisionally rated players may carry an inflated rating, we make use of a scaling down function for the K-factor based on their number of completed rated games. The scaling function is n/51 where n is the number of rated games that they have played.

You should try and focus on your overall standard of chess to improve your ChessWorld rating. You may find some good books to assist you - for example, visit the BookFinder page and check which books other Members own and which are the most helpful.

Chess is a game of skill. There are a huge number of different levels of understanding in Chess and it is possible for even strong International Chess Masters to be comprehensively beaten by top Grandmasters. Even top Grandmasters can, in turn, be demolished by players in the World Top 10 list. A rating system allows players to find evenly matched opponents or opponents slightly stronger, which can lead to more exciting two way games. The rating system can also show how strong one is relative to the overall population of ChessWorld Members.

Studying chess and practising can improve your overall rating, but there are no guarantees!

For your first 50 games your provisional rating is based on the English Chess Federation (ECF) Grading system. After the first 50 games, Elo calculations are used based on Classical Elo with a normal distribution curve.

There is a provisional rating period which applies to your first 50 rated games only.

Massive fluctuations will occur to your rating within the first few games until it settles down to reflect the performance of 50 games. Within the ECF rating system model used in the first 50 games, there is a 'Rating roof' implication.

If you are playing someone who is very much stronger than you in the ECF model, for example, 60 ECF points higher than you, then it is assumed that the difference is exactly 40. The reason for this is not to be able to gain points by losing to someone much stronger than you. A win under the ECF model is counted as your opponents rating +50, and a loss as your opponents rating -50. If their rating was more than 50 points higher than you, then losing against them would gain you points!

On ChessWorld, 40 ECF points translates to 320 rating points. For example, if you are rating 1200 on ChessWorld, and you are playing someone rated 2700, in fact it is like you are playing someone who is  a 1520 rating. The key here is, in your provisional period, to be content with playing people that are within a 320 point rating range and no more, if you are out for maximum points by beating the big guns. Playing players any stronger will have no impact until your rating increases and then your range increases.

After the first 50 games the rating system as described in detail above applies.

Your accumulated points are being averaged by a small number of games, and hence heavy fluctuations result in the first few games. As you play more games your rating will become more and more settled. You can see this fluctuation and how your performance changes by looking at your rating graph, which you can access via My Stuff ... My Ratings.

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 Opponents ... Join 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 Attribute box. 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 by visiting the Rating Classes page.

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.

The Rating Graph is accessed from the homepage. This means that, as well as viewing your own performance, you can look at any other player, your next opponent for example, to get a useful indication of their performance.

The Rating graph shows you your progress, as measured by your rating, over the last 50, or 100, games, with the latest result at the left hand side You can choose to display your record in different colours to highlight actual results, which helps to illustrate 'runs' of success or failure. To make your analysis simpler it is helpful to superimpose your opponents rating so that, when combined with the multi-colour option, it is easy to determine exactly why your performance varied over time. This combined graph is probably the most suitable for analysis as minor variations in your performance, which tend to be over-emphasised in the basic graph, are reduced.

As you hover over any one of the bars in the graph, the game details are shown in the left hand panel and the final position is shown on the mini-board. If you click on the mini-board you will be taken to the actual game where you will be able to use all the normal facilities provided on the ChessWorld game board.

The left hand panel shows basic game details, including your opponents current rating. To check ratings at the time the game was concluded hover the mouse over the relevant bar. You will see a message such as Player's Rating: 2500, or, if you hover over the small square that represents your opponent on the graph, you will see a message such as Opponent's Rating: 2500.

There is no simple answer to this question. However, most players tend to have quite slow changes in rating so a reasonably level graph is 'normal'.

For a good general impression, look at the Rating Graph showing the results in colour and with the opponents ratings superimposed. Most 'normal' graphs tend to show that the opponents rating fluctuates above and below your own rating. It would, however, be unusual if your opponents ratings were always above, or always below, your own rating.

Most 'normal' graphs show a mixture of results, and are unlikely to show exclusively either all wins or all losses over a 50- or 100-game range.

No! The ChessWorld Rating system is carefully designed to give due credit for the specific format of on-line Chess as played on the ChessWorld server. We have evolved a unique system, based upon well proven International standards, that is best suited to the demands and expectations of our Members. As such, it is quite reasonable to use your rating, once you have played more than 50 games, to give you an indication of your relative ability as compared with any given opponent on ChessWorld.

Because our system is designed specifically for ChessWorld there cannot be any meaningful comparison with the more common external measures that may be of interest. For example, ratings as awarded by ECF, FIDE and other formal bodies are based upon over-the-board, (OTB), play where it is possible to ensure carefully controlled and monitored conditions. The nature of web-based correspondence chess is such as to preclude any such controls, which cannot be replicated on this, or any other chess playing site.

In some cases, our Members may have recorded their current FIDE, or other, ratings on their homepage and you may get a very approximate comparison between that and their ChessWorld rating.. However, this should not be taken as a definitive conversion.

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.

In Mythology, of course, Hera is the wife, (and, in some versions, the sister), of Zeus.