Lap vs length

Friday 31 July 2015

My exercise is swimming, and it’s an important part of my day. I track my distance. Usually I swim a mile or so. To swim a mile in a 25-yard pool, you have to make 36 round trips.

I say this as, “36 laps.” The sign at my pool says a mile is 36 laps.

I was listening to the How to Do Everything podcast, and they had a question about whether a lap is once across a pool, or there and back. I smugly thought to myself, “there and back, of course.”

To answer the question, they asked Natalie Coughlin, an Olympic swimmer, who said,

In swimming, the lap refers to swimming from one end of the pool to the next. Without a doubt, it’s one end of the pool to the other. It’s not back and forth.

What!? How does this make sense? We already have a word for one end to the other, “a length.” Are we really going to use both words to mean the same thing, and then have no word for there and back?

In any other sport, a lap takes you from a starting point, out some distance, and then back to where you started. Why should swimming be different? I thought this was supposed to be an erudite sport?

Looking for a higher authority, I consulted the glossary at USA Swimming:

Lap: One length of the course. Sometimes may also mean down and back (2 lengths) of the course.

Thanks a lot... This definition both exposes the absurdity, by defining lap to mean precisely “a length,” and then throws out there that some people use the word differently (in the useful way), so we really don’t know what we’re talking about.

Can we do something about this? Can’t the universe make just a little more sense?


Are you swimming a mile or swimming a "swimmer's mile". That one still makes no sense to me.
@Matt: wow, I had never even heard of a swimmer's mile. 36 round-trips in a 25-yard pool is 5400 feet, which is slightly more than an actual 5280-foot mile. :)
You should call swimming around the whole circumference of the pool a "lap", to be more consistent with running, and also swim that way to annoy everyone else in the pool immensely.
Alexandre Beaulne 6:58 AM on 1 Aug 2015
I believe *part* of the confusion is because a large fraction of competitive swimmers train (most of the time) in 25 meters pools, but compete (most of the time) in 50 meters pools. Hence 1 length of racing == 1 lap of training.

s/25 meters/25 yards if 'Muricah
@Wooble: good idea, I'll let you know how it goes! :)

@Alexandre: this is an interesting point, and might provide some hope that there is at least a modicum of logic somewhere in here.
For a slightly different perspective, I did a lot of amateur competitive swimming in my teens, and length always meant to the other end of the pool. I don't recall lap being used, though when I read your post for some reason I thought of swimming across, rather than along, the pool.
Forgot to mention, but that's in Britain (not that I have any idea if my experience is representative).
Christopher Allen-Poole 3:48 AM on 2 Aug 2015
Because of the confusion, I almost always use the word "length" and forgo the word "lap". When I was on swim team "lap" and "length" were always synonymous, however.
Sounds like your training just got 50% easier.
Steven Rumbalski 4:20 PM on 30 Oct 2015
On an oval running track 1 lap equals the 1 length. Is the essence of a lap that it starts where it ends or that it runs full course?
The Oxford dictionary says
1.1 A stage in a swim consisting of two lengths (or one length) of a pool.
‘everyone did ten laps of the pool’ So it does not really help
Lap means both one and two lengths. Just use lengths and forget about laps.
This topic is frustrating. In my 44 years of competitive swimming (18 club, 4 college, 22 masters), I've always a known lap to equal two lengths of a pool. I only researched this topic because I run a program at our local pool where swimmers record their distances, and we had an equal mix of people subscribing to all definitions!? I refuse to move over to the dark side and state that one lap is equal to one length!
A lap is down and back in a pool. A length is just going down once...which is swimming the length of the pool. The distance doesn't matter. That's just what it is. It makes sense. :)
I have been swimming for 35 years at the Y. I use a swim “calculator.”
In a 25 yard pool, it tells me a length is one side to the other side is a length. It tells me a lap is swimming to the other side and back to the starting side. I have checked with swim staff also.
A lap in sports is one completion of the course. Once through a track is a lap and it brings you back where you started because it is a circle. Once through a pool is also a lap and it does not bring you back where you started because it is a straight line. Some people do use lap to mean two lengths but those people must either be confused or not competitive swimmers or maybe in a different country from me with different definitions for words. To differentiate between different sized pools we use “long course meters” and “short course meters” so a lap in a long course pool is 50 meters and a lap in a short course pool is 25 meters but a lap is always once down the pool.
People tend to think of laps the same way that a runner or a race car driver does a lap. It's the completion of the course. But in a pool, the course can be from one end to the other. It doesn't have to be over and back. Also, in the Olympics, they use a lap counter. It's on display for every swimmer to glance at during the race. The lap counter counts lengths. It does not count over and back. Sorry folks, but a lap is the same thing as a length. Anything longer than that is expressed in meters. This is especially true in a 50m pool, where swimming over and back is not called a lap, it's called a 100m.
By definition a lap on any race course in any sport gets you back to where you started in order to do another lap

So I swimming it’s the same
A lap is two lengths. Any one who says otherwise is a moron
For 50 years I've counted a lap as 2 lengths. A lap by definition is the completion of a course, which to me means down and back, a full circuit. I'd rather count laps this way than lengths, I don't have to count as high. When lap swimming and sharing a lane with other swimmers you actually swim up one side and down the other, in a circle, that to me is a lap. Defining a lap and a length to be the same thing is redundant and useless.

As many have already so clearly pointed out, a “lap” equals a single length in swimming; it’s just a fact. As defined, it’s about the completion of a course, and not all courses are circular. If you still think otherwise, you’re either too stubborn or too stupid to realize when you’re wrong.


Important test: When you say (in a short course pool), “I just got lapped,” do you mean that someone is 25 yards or 50 yards ahead of you? If you mean 50, then lap and length are two different things. If you don’t mean 50, you are insane. Ergo, a lap is down and back.


This confusion with comparing “length” & “lap” and saying they’re the same in swimming makes ZERO sense. As a swimmer for my entire life and a swim coach I have had this debate for decades and I have come to the conclusion that swimmers are the ones responsible for this confusion because they are trying to swim less distance (LOL) In a 25 yard pool a lap is 50 yards but by making the two different words synonymous swimmers will swim 25 yards and say they swam a lap. SMH

If you were asked what the length of a car is you would measure from one end of the car to the other, you would not measure from front to rear then do it again in reverse and say the car is twice as long as it really is.

A lap is when you have a starting point and you return to it as is the case in track & field or auto racing. In swimming, that’s down and back or two lengths of the pool.

The two words are not the same . Why do some people get to change the definition?

Gerald Meissner 9:20 AM on 2 Dec 2022

One part of the confusion is a 50 meter pool versus a 25 meter pool. I have always been taught that a lap is down and back (2 lengths). For a standard 25 meter pool that would be 50 meters per lap.

If however I had access to a 50 meter pool I would just use the term “lengths”.

I could see how a person swimming in a 50 meter pool however would want to use “lap” interchangeably with lengths.

Basically whenever I say a “lap” it would be 50 meters.

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