One lap in an Olympic-size swimming pool corresponds to about 108 yards. According to the Federation International de Natacion or FINA, the standard length for an Olympic-size swimming pool is 50 meters, or about 54 yards.
Swimming pools are also commonly built with 25 meter lengths; in this case, the length of a swimming lap is divided in half, making a lap about 54 yards. A swimming lap is generally defined as the distance to the far end of a pool and back again. The distance of a lap in pools with non-standard lengths can be found by multiplying that distance by two.