How this calculator works
The same swim takes different times depending on the pool. Short course yards is the shortest course and produces the fastest times because there are more turns and less open water. Short course metres sits in the middle, and long course metres is the slowest because a 50 m pool has half as many turns and more opportunity for stroke inefficiency. The page applies the classical USA Swimming factors: multiply short course yards by 1.11 to compare with short course metres, then multiply short course metres by 1.02 for long course metres. Combining the two gives 1.1322 from short course yards to long course metres. Dividing reverses the conversion.
Formula
Converted time = swim time x factor of the target course / factor of the source course. Factors are 1.00 for SCY, 1.11 for SCM and 1.1322 for LCM. For example, SCY to LCM multiplies by 1.1322, and LCM to SCY divides by 1.1322.
Worked example
A 100 m freestyle swum in 1:00.00 short course yards is 60.00 seconds. Converting to long course metres gives 60.00 x 1.1322 = 67.93 seconds, or 1:07.93. The same swim in short course metres is 60.00 x 1.11 = 66.60 seconds, or 1:06.60. A 1:05.00 long course swim converts back to 65.00 / 1.1322 = 57.41 seconds in short course yards.
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Frequently asked questions
Why are yards faster than metres?
A short course yards pool is 25 yards, about 22.86 m, so a race has more turns and a shorter total distance than its metre equivalent. Turns add speed through push-offs, so the time is lower even though the effort is similar.
Are these factors official?
The classical 1.11 and 1.02 factors are widely used for comparison and in some qualifying contexts, but official bodies use event-specific factors and cut-off calculations. Check the meet or federation rules before using a converted time for entry.
Why does the stroke matter?
Breaststroke and butterfly lose more time in long course because each turn is a chance to carry speed, while freestyle and backstroke are less affected. The page uses one factor for all strokes, so breaststroke conversions are the least reliable.
What about 400 m and 500 yd events?
Those events are not the same distance, so their conversion is not simply a course factor. USA Swimming uses different factors for distance events, and the page does not apply them, so treat those rows as a rough comparison.