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SESK: Stuff Everyone Should Know · sesk.info/swim-lengths-in-a-100

In a 25-yard pool, how many lengths make a 100-yard swim?

Four lengths of 25 yards each.

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  1. Two lengths
  2. Eight lengths
  3. Four lengths ✔

Why: A length is one trip from end to end. In a 25-yard pool, 100 yards is 4 lengths. People disagree whether a lap is one length or down and back, so swimmers count lengths.

Huh, didn't know that: A short course pool is 25 yards or 25 meters long; long course is 50 meters.

The dad joke
Why did the swimmer count every length? Because every length counts.
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References

Answer: Four lengths. A length is one trip from end to end. In a 25-yard pool, 100 yards is 4 lengths. People disagree whether a lap is one length or down and back, so swimmers count lengths.

  1. USA Swimming Rulebook 2026, definitions www.usaswimming.org/docs/default-source/governance/governance-lsc-website/rules_policies/rulebooks/2026-rulebook.pdf
    extent of the course from end to end.
    Checked 2026-10-12.
  2. USA Swimming Rulebook 2026, definitions www.usaswimming.org/docs/default-source/governance/governance-lsc-website/rules_policies/rulebooks/2026-rulebook.pdf
    25 yards or 25 meters.
    Checked 2026-10-12.

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