What is the difference between short course and long course swimming?

Short course (SCM) is swum in a 25-metre pool, long course (LCM) in a 50-metre pool. The strokes and distances are the same; the difference is the number of turns. A 100m race has three turns in short course but only one in long course.

Why are short course times faster than long course times?

Turns are the fastest part of a race: swimmers push off the wall faster than they swim, and each push-off carries them several metres underwater. Short course doubles the number of walls, so times are typically one to two seconds faster per 100m, with a bigger advantage for swimmers who have strong turns and underwaters.

Is a short course PB a real PB?

Yes — but it is a different PB. Short course and long course are kept as separate records for every event, and comparing one against the other misreads progress. A swimmer whose SCM 100m freestyle is faster than their LCM 100m freestyle is entirely normal.

Can short course times be converted to long course?

Approximate conversions exist and some meets accept converted times for entry. But conversions are estimates: they assume average turn ability, and swimmers with unusually strong or weak turns will convert differently. Where a championship requires long course times, the safest plan is to race long course meets inside the qualification window.

Parent's guide

Short course vs long course: why the times differ

Same stroke, same distance, different pool — and reliably different times. Here is why, and what it means for PBs and qualifying.

Short course (SCM) races are swum in 25-metre pools and long course (LCM) races in 50-metre pools, and short course times are reliably faster — typically one to two seconds per 100 metres. Nothing about the swimmer changes; the pool does. Once you know why, several confusing things about your swimmer's results start making sense.

Turns are free speed

A swimmer leaves the wall faster than they swim, and the push-off carries them several metres underwater at speed. A 100m race in a short course pool has three turns; the same race long course has one. Every extra wall is a small time gain, which is why the short course advantage grows with distance — and why swimmers with strong turns and underwater kick gain the most from a 25m pool.

Two separate sets of PBs

Because the courses time differently, every event effectively has two records: a short course PB and a long course PB. They should never be compared directly. A swimmer who clocks 1:10 in an SCM 100m freestyle and 1:12 LCM has not gone backwards — that gap is the expected course difference. In Australia, the summer season is predominantly long course and winter short course, so families often see times “jump around” between seasons when really the course has changed, not the swimmer's form.

What it means for qualifying

Qualifying times are course-specific. Long course championships generally want long course times, though some accept converted short course times under stated rules. Conversions assume average turn ability, so treat them as estimates rather than entitlements. If a long course championship is the goal, plan long course racing inside the qualification window — our qualifying times guide explains how windows and standards work. You can also look up specific qualifying times for every state and national championship in the QT calculator.

Rule of thumb: roughly 1–2 seconds per 100m between SCM and LCM for age-group swimmers, growing with race distance and turn quality. Individual swimmers vary — keep each course's PBs separate and the confusion disappears.

See both courses, side by side.

SwimProgress keeps SCM and LCM PBs separate automatically, shows progress on each, and compares your swimmer against qualifying times in the right course — free during early access.

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