Tennis Scoring Has Always Been Weird — Why Does It Go From 15 to 30 to 40?

Aug. 30 2023, Published 2:27 p.m. ET

Sports have always had weird rules and terminology. Football has a line of scrimmage that even seasoned fans may have difficulty really explaining. More people recognize reaching bases as dating lingo rather than as part of baseball rules. And the extent of knowledge that the average person has about basketball may likely amount to knowing how to dribble a ball. But of all the sports with confusing and baffling rules and jargon, tennis stands above them all.

You might think there wouldn't be much to worry about with a game of two to four people hitting the same ball at each other while trying to stay in bounds. Heck, it's not as if volleyball — which is remarkably similar to tennis — has too many complexities to wrap your head around. But tennis has so many rules and strange conventions that one would be forgiven if one couldn't understand all of it. For instance, why is the score tracked by 15, 30, then 40? There are actually several theories.

Why is tennis scored by 15, 30, 40?

The basic rules of tennis are simple enough. Two players hit the ball back and forth in an effort to make sure their opponent misses the ball as it bounces out of the field. But unlike its virtual successor in Pong, you don't score a straight-up point just by getting the ball past the other person. You have to win individual sets to get onto the scoreboard. Those sets are won through a scoring system where players reach 15, then 30, then 40 every time they get the ball out.

Once they get the ball out past 40 (barring any deadlocks or advantage points), they officially win the set and technically, earn a point from there.

But where did a scoring convention like this even originate? Based on our research, not even tennis historians have a clear answer. What we do know is that this system has been in place since the 15th century. According to The Tennis Bros, French tennis games already employed this system during the 1400s.

As for where the system came from, there is one theory that has been circulated among tennis enthusiasts. This theory suggests that early games of tennis had their scores displayed on giant clocks. The "clock hands" would be moved a full quarter every time a player scored, hitting the "15," "30," and "45" marks with each volley. Once it went all the way around for one player, the set would go to them. It certainly sounds plausible, even though we now use "40" instead of "45".

However, a report by Time magazine indicated that minute hands on clocks were only introduced in the late 1500s, which doesn't necessarily line up with the timeline of tennis' existence.

Still, the "clock hands" theory remains one of the most prominent explanations for tennis' weird scoring system. Now if only someone could explain "love".

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