Convert pool lengths to distance.
The word lap is ambiguous in swimming: in most pool programmes it means one length, but in competitive usage borrowed from athletics it means there and back. That single distinction doubles the distance, which is why it is an explicit input here. Lengths per kilometre is the useful reference for setting sessions — forty lengths of a 25 m pool, or twenty of a 50 m pool.
Swim distance from laps
Distance = laps x lengths per lap (1 or 2) x pool length; lengths per kilometre = 1000 / pool length
These figures are population-average estimates for training and recreational planning only and are not medical advice. Individual responses vary widely. Consult a qualified health professional before starting or significantly changing an exercise programme, particularly if you have any medical condition. Official dimensions, rules and timings should be confirmed against the governing body for your sport.
In most pool sessions and lap-counting devices, one length. In traditional competitive terminology a lap is down and back, which is why totals can differ by a factor of two.
Sixty-four lengths of a 25 m pool is 1,600 m, close to a mile. The traditional swimmer's mile of 1,650 yards is 66 lengths of a 25-yard pool.
Usually — fewer walls means fewer push-offs and no chance to break up the effort, so the same distance is measurably more demanding.