How do tennis rankings work?

The ATP and WTA rankings are computed from points earned over a rolling 52-week window. Each tournament awards points on a scale tied to its tier and to how far a player advances, with the four Grand Slams worth the most, then the top-tier tour events, and so on down. A player's ranking counts a fixed number of their best results across the year, with the Slams and the mandatory big events counting automatically and remaining slots filled by the best of the rest. The number one player is simply the one with the most points on the Monday the rankings update.

The rolling window produces the dynamics that confuse viewers. Points from a tournament expire when that tournament is played again the following year, so a player defending a title earns nothing net by winning it again and loses a large block by losing early. That is why commentators talk about defending points and why a player can rise in the rankings during a week they did not play. Injuries are handled through a protected ranking that lets a returning player enter events at their pre-injury level for a limited period without affecting the live rankings.

Rankings determine everything practical: direct entry into tournaments, seeding that separates the top players until later rounds, and qualification for the year-end championships. Two things that are often misunderstood. Rankings are not head-to-head records, so a player can be ranked above someone they have never beaten. And the men's and women's systems are similar in structure but administered separately, with different tournament calendars and points scales, so a number is not comparable across them. Doubles carries its own separate ranking.