Frequently Asked Questions

What is the ITF World Tennis Number?

The ITF World Tennis Number provides a global standard for players. It is a 40-1 scale, with 40 being a beginner player and 1 being an elite professional. This scale is for all players, regardless of age, gender, or ability. Players will have separate ITF World Tennis Numbers for singles and doubles.

How is it calculated?

The WTN algorithm uses match results from 2016 onwards to calculate a player’s number. When players compete, it analyses the pre-match rating of both players. The algorithm then predicts what it thinks the outcome of the match will be. Players’ WTNs will change depending on the actual match score and how it compares to the prediction. The more results the system holds, the better the algorithm will understand a player’s ability, and therefore, its “confidence” in the player’s Number will increase. Match results are analysed at a set level, meaning the algorithm takes into account each individual set as its own result.

How will my Number be updated and how often?

The ITF World Tennis Number is a dynamic system that updates on a weekly basis (every Wednesday) to provide a ‘real time’ measure of player standard and allows players to more closely and better track their progress.

What scale will the ITF World Tennis Number use?

The ITF World Tennis Number Scale is from 40 (lowest) to 1 (highest).

All players will appear on one scale from the very best professionals on the tour to a complete beginner who is playing their first match. Depending on where you are in the world, you might also see your Number display one or two decimal places. This allows you to know with even greater precision where your game is at, allowing you to find a partner even more suited to you! 

What is the Game zONe?

Game zONe is the range of player ratings where you will achieve the most competitive matches.  This range includes players with slightly higher and lower WTNs than your own.  Gaining match results within your Game zONe is the fastest way to improve your WTN.

Every player with a singles WTN equal to or greater than 10 should have a Game zONe.

Singles WTN lower than 10 does not have a Game zONe.

Doubles WTN does not have a Game zONe.

How is Game zONe determined?

Game zONe is your range of opponents where either player would have a probability of winning the match of between 35%–65%.

What is the Confidence Level?

The Confidence Level is a measure of how accurate your rating is. A blue checkmark to the right of your WTN indicates a high level of confidence in your rating’s accuracy and therefore your number is considered verified.  A grey checkmark to the right of your WTN indicates a lower level of confidence in your rating’s accuracy.  To increase your confidence factor, you’ll need to play more matches.

How is my Confidence Level determined?

The more matches you play, the more confident your rating will be. As a guide, a player with little or no results history could achieve a verified WTN if they compete in 5 or more matches in a 5 consecutive week period. If you play a match every 2 weeks, your Confidence Level will not decrease.

What is the relationship between the WTN rating and its Confidence Level?

The Confidence Level is derived from a quantity called rating deviation in the Glicko-2 methodology. A player’s rating is a central measure of his/her estimated ability. The rating deviation augments the knowledge of that estimate by providing a measure of uncertainty around that central measure.  As the rating deviation decreases, the algorithm becomes more certain on the central estimate. Confidence Level is a transformation of rating deviation.

The Confidence Level can have a significant impact on a player’s rating. Faced with the same set of results, two players with the same rating, but with different Confidence Levels, will experience different rating updates. The player with a lower Confidence Level will see his/her rating fluctuate more.

The factors that make the Confidence Level change are stated in the previous section.

Does the score matter in the calculation of the WTN?

Yes, match results are analysed at set level, meaning the algorithm takes into account each individual set as its own result. The WTN algorithm compares its score prediction with the actual score to determine what a player’s specific rating should be.

Does a retirement impact my WTN?

A retirement where a set has been completed does count toward a player’s WTN.

What happens to the ITF World Tennis Number of a player that is inactive over a long period?

During time periods in which a player does not compete, their rating remains unchanged, but their confidence level decreases. This is the way the algorithm captures the increased uncertainty around a player’s rating.

Players who do not take part in competition for a significant period, caused by injury, off-court issues or other factors, will have a lower confidence level when they return to play.  The algorithm will react more strongly to the results as it tries to calibrate the player’s rating after a long absence of data.

I won my match. Why did my rating go down?

Your match results, despite winning, may not have met or exceeded the algorithm’s projection. As an example, if the algorithm projects a 90% chance of winning and the match is won 2-1 on sets, you will not have met or exceeded the algorithm’s projection.

I lost my match. Why did my rating go up?

Your match results, despite losing, may have exceeded the algorithm’s projection. As an example, if the algorithm projects a 90% chance of winning and the match is won 2-1 on sets, you will not have met or exceeded the algorithm’s projection.

How can I improve my WTN?

If your aim is to improve your game and therefore your Number, it couldn’t be simpler. All you need to do is keep playing and performing better than our algorithm predicts you will. If you want to see your Number improve each week, be sure to stay active on the court. 

Broadly, winning sets against opponents with a similar or better rating will improve your WTN. Losing sets against players with a similar or worse rating will worsen your WTN. In short, the better the rating of your opponent is, the bigger the impact of a positive result. However, it is also worth noting that the confidence level can be a factor. 

Why has my historic/current WTN changed without playing recently?

The WTN looks at all ratings and matches played across the whole system. The WTN continues to add new historic matches from different sources which can cause fluctuations in player ratings despite them not having played any additional matches. This is due to the rating showing the skill level relative to all peers. New matches and new players being added can change the comparison to ‘peers’.

For example, some of the reasons the rating can change are:

  • Someone you played against has had more historic matches added which has made their rating more accurate at the time of the match
  • There has been an update to the algorithm to improve performance and accuracy (these changes are announced in advance and are unlikely to happen more than once a year).

Are singles ratings used to calculate doubles ratings?

No, the singles and doubles algorithms are separate. 

Why is my doubles rating higher/lower than my singles rating?

The singles and doubles ratings are on the same scale but are not meant to be directly compared to each other. It is common to see players whose singles and doubles ratings differ by more than 1.00. A player's doubles rating shows their doubles skill level relative to their peers.