How many laps is 1.2 miles swimming? Lengths per pool

Swim pace per 100 yards or meters, from a single swim

A swimmer's mile in a US pool is 1,650 yd. Swum in 30:00, that is 1:49.1 per 100 yd, which sounds quick until you read the same effort per 100 meters: 1:59.3. This swim pace calculator works in either unit and always prints both. It gives the pace from a distance and a time, the time for any distance from a pace, your critical swim speed (CSS) from a 400 and a 200 test, and the number of pool lengths in a set or a race.

Yards and meters are not interchangeable. 100 yd is 91.44 m, so every pace per 100 yd is about 9% faster on paper than the same swim per 100 m. A triathlete who trains in a 25 yd pool and races a 1,500 m course has to convert, or the race plan is off by minutes.

From the pool clock to a pace in six moves

The form changes with the first choice, so only the boxes the question needs are shown. The example is the swimmer's mile above.

Calculate - pace from a time, time from a pace, CSS from a test, or pool lengths for a distance. After a workout you want the first; before a race, the second.
Units - yards or meters, matching the pool or the course. The distance, the pace and the CSS test all follow this choice, and the result adds the other unit next to it.
Distance - the swim in yards or meters, from 25 to 20,000. A mile is 1,760 yd; the swimmer's mile of US pools is 1,650 yd. In the example: 1,650.
Swim time or pace - whole minutes in one box, seconds with tenths in the other. Use the moving time: a watch that keeps running during rests at the wall makes the pace look slower than it was. In the example: 30 and 0.
Pool - optional. Pick 25 yd, 25 m or 50 m to get the number of lengths and the time for each; pick open water, or leave it empty, to get the halfway split instead. In the example: 25 yd, which gives 66 lengths at 0:27.3 each.
Read the result - the pace or the time at the top, the same pace in the other unit, your speed in mph and km/h, and a table of popular pool and triathlon distances at that pace.

25 yards, 25 meters or 50 meters: what changes

The pool length does not change the arithmetic of pace, but it changes how many lengths a set takes and how long each one lasts. The table uses a pace of 2:00 per 100 m for the last row.

What you count	25 yd pool	25 m pool	50 m pool
One length	22.86 m	25 m	50 m
Lengths in 1,500 m	65.6	60	30
Lengths in a mile (1,760 yd)	70.4	64.4	32.2
Lengths in a swimmer's mile (1,650 yd)	66	60.4	30.2
One length at 2:00 per 100 m	0:27.4	0:30	1:00
Which unit to type	yards	meters	meters

The last row is the whole rule: type the unit of the pool you actually swam in, and let the calculator convert the pace. Converting the distance first and the pace afterwards gives the same answer, but it is one more place to slip.

The three formulas, applied to real swims

Pace per 100 is the time divided by the distance, times 100. Time is the pace times the distance, divided by 100. CSS pace per 100 is the 400 time minus the 200 time, divided by 2, because the difference between the two swims is the time the extra 200 took.

Pace. 1,650 yd in 30:00 is 1,800 s. 1,800 / 1,650 x 100 = 109.1 s, or 1:49.1 per 100 yd. Divided by 0.9144 it becomes 1:59.3 per 100 m, about 1.88 mph.

Time. An Olympic triathlon swim of 1,500 m at 2:00 per 100 m takes 120 x 15 = 1,800 s, or 30:00. The Ironman swim of 2.4 mi, which is 3,862 m, takes 1:17:15 at the same pace, and the 1.2 mi of an Ironman 70.3 (1,931 m) takes 38:37.

CSS. 400 m in 6:00 (360 s) and 200 m in 2:52 (172 s): (360 - 172) / 2 = 94 s, so CSS is 1:34 per 100 m, or 1.06 m/s. The calculator then lists training paces around it: easy 1:42 - 1:44, steady 1:38 - 1:41, threshold 1:34 and speed work 1:29 - 1:32. Those bands follow the Effortless Swimming convention of +8 to +10, +4 to +7 and -2 to -5 seconds per 100; they are a coaching habit, not a standard.

One pace per 100 yd, read per 100 m and timed over three race distances

Pace /100 yd	Pace /100 m	1,500 m	70.3 swim	Ironman swim
1:30	1:38.4	24:36	31:41	1:03:22
1:45	1:54.8	28:42	36:58	1:13:55
2:00	2:11.2	32:49	42:14	1:24:29
2:15	2:27.6	36:55	47:31	1:35:02
2:30	2:44	41:01	52:48	1:45:36

The race columns assume the pool pace holds all the way, with no wall to push off every 25 yards. Most swimmers lose time in open water, so read them as the best case for the day.

Five ways a swim pace comes out wrong

Reading 100 yd as 100 m. A 1:49.1 pace from a yard pool planned as 1:49.1 per 100 m promises a 1,500 m swim in 27:17. At the real pace it takes 29:50, which is 2:33 slower. Choose the unit of the pool, not the unit of the race.

Timing the rests. The same 1,650 yd with five minutes of breathers on the clock reads 35:00 and becomes 2:07.3 per 100 yd instead of 1:49.1. Use the moving time, or swim the distance without stopping when you measure.

Pacing the CSS test badly. Going out too fast on the 400 or holding back on the 200 squeezes the gap between them. When the 400 pace comes out no slower than the 200 pace, the calculator refuses the result and asks for a new test instead of printing a CSS that is too fast.

Racing an Ironman at CSS. Critical speed has been held for only about 14 to 39 minutes in lab trials, and the 200 and 400 pair gives a faster figure than tests that include swims of 800 or more (Scott, Burden and Dekerle, Journal of Human Kinetics 90). A 1:34 CSS would put the Ironman swim at 1:00:31; expect the real one to be slower.

Counting laps instead of lengths. In a 25 yd pool a swimmer's mile is 66 lengths. Count there and back as one lap and it is 33 laps. Both are right, but a plan written in one and swum in the other ends a mile short or a mile long.

Swim pace questions from the pool deck

What pace do I need to make the Ironman swim cutoff?

Most IRONMAN races close the swim 2 hours 20 minutes after your start, and most 70.3 races after 1 hour 10 minutes; the athlete guide of your race has the final word. Both work out to the same average: 3:37.5 per 100 m, or 3:18.9 per 100 yd. Type 3,862 m in the time mode with your own pace to see the margin.

How many laps is a mile in a 25 yard pool?

A full mile of 1,760 yd is 70.4 lengths. Pool workouts usually round it to the swimmer's mile of 1,650 yd, which is 66 lengths, or 33 if a lap means there and back. In a 25 m pool a mile is 64.4 lengths.

How do I convert a pace per 100 yards to per 100 meters?

Divide the seconds by 0.9144. A pace of 1:40 per 100 yd is 100 s, and 100 / 0.9144 = 109.4 s, or 1:49.4 per 100 m. Going the other way, multiply by 0.9144. The calculator prints both, so there is nothing to convert by hand.

Why is my pace faster in a 25 yard pool than in a 50 meter pool?

Every length starts with a push-off and a glide, which are faster than swimming. A 25 yd pool gives you about 66 of them in 1,500 m, a 50 m pool only 30, and open water none. That is one more reason to treat a race time from a short pool as optimistic.

Can I do the CSS test in yards?

Yes. Swim 400 yd and 200 yd, choose yards, and the CSS comes out per 100 yd with the meter pace beside it. Swim both from a push-off rather than a dive, with a full recovery between them, so the two times are comparable.

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How many laps is 1.2 miles swimming in a 25 yard pool?

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