Most fans will have at least one moment during the season when they need to figure out how the tennis rankings actually work. A big one came overnight leading into Monday October 21, when Aryna Sabalenka overtook Iga Swiatek as the women’s world No. 1 because of an unheralded WTA Tour rule that the organization did not explain or forecast before making the change.

This part of the tennis calendar is generally a good time to have a grasp on them, as players up and down the ATP (men’s) and WTA (women’s) rankings race for the end-of-season Tour Finals at the top and the seeding and main draw places for the Australian Open in the lower echelons.

Players get more than $300,000 ($231,000) just for showing up at the Tour Finals while winning a round-robin match carries a prize of nearly $400,000. Dozens of players hovering in the neighborhood of 26-60 are desperately trying to hold steady or catch fire to finish the year in the top 32 so they can just about lock-in being seeded in Melbourne for 2025. Further down, the top 104 are trying to avoid having to go through qualifying.

“I’m kind of interested in how the rankings and the awarding of these points actually work. I’m going to try to figure it out,” any given tennis fan might say, before navigating to either the men’s or women’s lists, being greeted with a long line of opaque numbers, and deciding that if they’ve survived for this long without understanding the system, another year is just fine.

Dearest tennis fan, we feel you. So much so that we’ve endeavored to explain the rhyme and reason of tennis rankings, even if this should not be perceived as an endorsement of the existing system, which is fraught, to say the least.

Here is how tennis rankings work, how tennis players are ranked, and why it sometimes gets complicated.

GO DEEPER

Why Sabalenka has replaced Swiatek as No. 1 in the WTA rankings

When were tennis rankings invented and why do they exist? 

The official tour rankings date to the 1970s, the first years of the so-called ‘Open Era’ of tennis. That was when the people who ran tennis started to permit professionals and amateurs to compete in the same tournaments, most importantly the Grand Slams. The ATP rankings were introduced in the summer of 1973, but their current iteration dates from 1990.

The WTA rankings were introduced in 1975. Both rankings systems are computerized — ‘Blinky’ calculates the men’s and ‘Medusa’ the women’s — which is why some tennis records are dated since the “introduction of computerized rankings.” Players are awarded points for their results and their points determine their ranking.

Steffi Graf has the most weeks at No. 1 on the WTA Tour, with 307. (Gary M. Prior / Allsport via Getty Images)

Ultimately, tennis needed a fair way to decide who qualifies for each tournament and how they should be seeded in those tournaments. If you think the current rankings system is a mess, it is a model of precision and justice compared with the old system of tournament directors doling out invitations and seedings as they pleased. Things got so bad that the ATP was created as a union for players in 1972, before organizing a large-scale boycott of the 1973 Wimbledon Championships.

How do tennis players earn ranking points?

Players earn points on both tours by winning matches and, they hope, tournaments. A sliding scale assigns each tournament a number of points to be awarded to the winner, beaten finalist, semifinalists, and so on. Tournaments are also categorized according to importance, which is embodied by the prize money players can win as well as the ranking points they can earn.

The four Grand Slams, which are the most important tournaments, deliver the most points, awarding 2000 to the winner and 1300 to the finalist, down to 10 points for players who lose in the first round.

All the other tournaments are categorized by how many points the winner collects. Starred figures in the ATP table indicate rounds that can be included or excluded according to the size of the draw at the tournament:

The next most important tournament is the Tour Finals, which on both tours awards a maximum of 1500 points to an undefeated champion, but only eight singles players can qualify for those, so the next truly significant category is the 1000-level tournaments. The ATP Tour refers to these as Masters 1000s, while the WTA Tour labels them as WTA 1000s. They include six combined events: Indian Wells in California; the Miami Open; the Madrid Open; the Italian Open in Rome; the Canadian Open, which alternates between Toronto and Montreal, and the Cincinnati Open.

Just to add a wrinkle of confusion, the WTA also has a series of 125-level tournaments. These are listed alongside its main events on the calendar but are considered a secondary event circuit despite not being formally designated as such.

The ATP Tour cuts off at 250-level events. Its 125-level events are part of the ATP Challenger Tour, but those events and WTA 125s can still constitute part of a player’s full ATP or WTA ranking if, for example, they win a few Challengers or 125s and so qualify for higher-level events.

And how is their ATP or WTA ranking calculated?

On both tours, the rankings look backwards 52 weeks, so you always have the number of points you have earned during the most recent year. Points then “drop off” a player’s total 52 weeks after they were awarded. Tournaments don’t always line up exactly in the calendar, so on occasion points will drop off before the following edition of a tournament, rather than after it.

The tours are divided, however, on which events constitute a player’s ranking and on which events in the tennis calendar players must play. To begin, each has a number of mandatory events, with some stipulations around qualification and ranking:

Both tours then set a limit on the number of events that can be included in the calculation of ranking points totals to prevent the volume of tournaments played from unfairly outweighing performance in those tournaments. On the WTA Tour, the best 18 results count — 19 if a player qualifies for the Tour Finals. On the ATP Tour, it’s the best 19 — 20 if a player qualifies for the Tour Finals.

The tours also divide their events differently. Both the ATP and the WTA include the four Grand Slams and six 1000-level combined events in their rankings calculations. That makes 10 events, plus their respective Tour Finals if the player in question makes it there. That’s 11 events.

This is where things get slightly complicated because the China Open is a combined event, but is only a 1000-level tournament on the WTA Tour; it is a 500-level event on the ATP Tour. Where the ATP just uses the six combined events which are 1000-level across both tours, the WTA takes the best six results from any combined event that includes a WTA 1000 — the six shared 1000s, and the China Open.

Then they diverge further. The ATP Tour uses its two further mandatory Masters 1000s — the Shanghai Masters and the Paris Masters — to make 13 events, but a player can replace up to three of their Masters 1000 results with higher points totals from ATP 500 or ATP 250 tournaments.

Those results are followed by the next seven best results in any class of tournament to make 20 for a player who qualifies for the Tour Finals, and 19 for a player who does not.

The WTA instead uses the best result at one of the three mandatory, WTA-only 1000 tournaments — the Qatar Open, the Dubai Tennis Championships, and the Wuhan Open. This makes 12 events, followed by the seven best results in any class of tournament to make 19 for a player who qualifies for the Tour Finals, and 18 for a player who does not.

What does ‘defending’ ranking points mean?

To recap: players earn points at a tournament. The points stick around for 52 weeks and then they drop off. That means that when a player enters a tournament, they still have the points they earned at the previous edition. This is known as ‘defending’ and it means the best players of the previous year are most at risk in the following. Win a Grand Slam title for 2000 points and then lose in the first round? Expect a precipitous drop in ranking.

What’s the difference between the tennis world rankings and the ATP and WTA ‘Races’?

Both tours keep a separate scoreboard that tracks the race to qualify for the season-ending Tour Finals. That scoreboard, known as ‘The Race’, begins at the start of the season, since by the end of it all the points from the previous season will have been dropped. The top eight players in each race qualify for the season-ending Tour Finals, except when they don’t.

This year, Barbora Krejcikova will take the eighth spot at the WTA Tour Finals in Riyadh, Saudi Arabia, despite finishing outside the top eight in the rankings. This is a special provision for Grand Slam champions who finish outside the top eight in the year that they win a Grand Slam title — provided that they do not finish outside the top 20 in the race.

The ATP race is still to be decided, with Jannik Sinner, Carlos Alcaraz, Alexander Zverev, and Daniil Medvedev all qualified for the Tour Finals in Turin, Italy.

Carlos Alcaraz at last year’s ATP Tour Finals in Turin, Italy (Tiziana Fabi / AFP via Getty Images)

How do the tennis rankings affect tournaments?

Rankings are used to seed players — the top 32 at a Grand Slam tournament and most 1000-level tournaments, then the top 16 or top eight at smaller tournaments. Seedings are calculated from the ATP or WTA rankings around a week before a given tournament starts. Then there are those races for the top eight, to qualify for the Tour Finals, and smaller races further down the rankings that can make the difference between direct acceptance into a main draw or having to go through a qualifying tournament.

In tennis, high-ranked players don’t have to play anyone in their ranking neighborhood until the later rounds of a big tournament. They get byes, which means automatic money and rankings points. Success generates opportunities for more success.

(Top photo: Aryna Sabalenka with the WTA world No. 1 trophy; by Robert Prange / Getty Images)