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.

Dennis Doughty 1:23 PM on 2 Aug 2015

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. :)

Paula Salcido 11:09 PM on 11 Jul 2020

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.

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