How the ATP and WTA rankings work
The ATP rankings are calculated by adding a player's points from 18 tournaments over a 52-week rolling window. The four Grand Slams, the eight ATP Masters 1000 events and the ATP Finals are mandatory. Players can count their best six results from the other ATP events.
The WTA rankings work on a similar 52-week rolling window, with 16 tournaments counted. The four Grand Slams, the eight WTA 1000 Mandatory events and the WTA Finals are mandatory. The top eight players qualify for the WTA Finals.
The Grand Slam format
Each Grand Slam is a 128-player single-elimination draw, played over two weeks. The men's singles is best-of-five sets; the women's singles is best-of-three sets. The draws are seeded 1-32, with the top two seeds placed at opposite ends of the bracket.
The Australian Open is played on hard courts in January. Roland Garros is played on clay in late May and early June. Wimbledon is played on grass in late June and early July. The US Open is played on hard courts in late August and early September.