The ITF World Tennis Number is a dynamic system that updates on a weekly basis (every Wednesday morning) to provide a ‘real time’ measure of player standard and allows players to more closely track their progress. The WTN scale is from 40.9 (lowest) to 1.0 (highest).
Players will be able to move in both directions along the scale. However, this will be solely based on their performances. Winning a match or playing a match does not guarantee a move in your WTN. The calculation makes a prediction before each match and how a player performs compares to that prediction and dictates if they move closer or further away from 1.
The ITF World Tennis Number pre-match prediction is not as straightforward as win or loss as the algorithm will predict the percentage chance of certain outcomes and change player’s numbers in relation to that.
This means that regardless of the level of two players competing against each other (whether they have a lower ITF World Tennis Number than each other or not), if a player performs better than the algorithm predicts, then their ITF World Tennis Number may go up.
Additionally, a WTN that is stable and doesn’t move often is a sign of an accurate reflection of a players’ ability.