Pool lengths

Enter a swim distance and your pool length to see how many lengths it is.

Your details

Pool
Distance to swim
Your pace per 100 m (optional)
Stroke
Your weight
Swims like this a week (optional)

1,500 m in a 25 m pool

60

lengths

  • Distance you will actually swim1,500 m
  • Time at 2:15 per 100 m33:45
  • Each length0:34: glance at the clock every four lengths to keep count
  • Energy, front crawl, slow (MET 5.8)228 kcal
  • Lengths for 1 km40
  • Lengths for a mile65
  • Count in sets offour lengths, then tick one off

Losing count is part of swimming. Split it into chunks, change stroke every set, or move a float at the end of each block.

The working

1,500 m in a 25 m pool

1,500 ÷ 25 = 60 lengths. At 2:15 per 100 m that takes 33:45. A kilometre is 40 lengths and a mile is 65 lengths (1,625 m, since you finish at a wall).

Common pools

Lengths per distance

Pool1 km1 mile
25 m4065
33.3 m3049
50 m2033
25 yards4471

Time and energy

From your pace

At 2:15 per 100 m each 25 m length takes about 34 seconds and 1,500 m about 33:45. The 2024 Adult Compendium gives steady front crawl 5.8 METs, so an 11 stone swimmer uses about 230 kcal; fast front crawl is 9.8 METs, breaststroke 5.3 and backstroke 4.8.

Keeping count

Tricks that work

  • Count sets of four lengths
  • Change stroke every set
  • Use a lap counter ring or watch
  • Say the number on each push off

Your week

Against the UK activity guide

The UK Chief Medical Officers advise 150 minutes of moderate activity a week, or 75 vigorous, or a mix. Activity of 6 METs or more counts as vigorous, so fast front crawl minutes count double. Two steady 1,500 m swims at 2:15 per 100 m are 68 minutes of moderate activity, leaving 83 minutes to find from walking, cycling or about three more swims. At a fast front crawl effort the same minutes count as 135, so 15 are left.

Read with care

What this cannot tell you

  • Pool sizeSome older pools are not quite their stated length.
  • RestTime does not include rests at the wall.
  • StrokesYour pace changes with stroke.

Questions

Common questions

How many lengths is a mile in a 25 m pool?

64.4, so 65 lengths to finish at the wall.

How many lengths is 1 km?

40 lengths of a 25 m pool or 20 of a 50 m pool.

Is a length the same as a lap?

It depends who you ask. Here a length is one end to the other.

Sources

Last checked 21 October 2026. Spotted something wrong? Tell us and we will fix it.

Before you push on

New to exercise, or got a heart, lung or joint condition? Have a word with your GP or practice nurse first. Stop and get help if you feel chest pain, faintness or unusual breathlessness, and call 999 if it is severe.

Related

Related calculators