Based on specifications published by FINA, the body recognized by the International Olympic Committee for governing international competition in Aquatics, an Olympic-size swimming pool must be 50 meters long. Pools used for Olympic competition must meet a variety of additional dimension requirements.
FINA is very particular with its dimension requirements for Olympic-size swimming pools. The allowed length tolerance is only 0.03 meters, meaning that all Olympic-size pools measure between 49.97 and 50.03 meters long, even when electronic timing devices are installed in the pool.
Due to the uniform length of Olympic-size pools, swimmers easily compare their times for a particular event across various locations and dates. Race officials are assured that world records, when set, are fairly earned over the appropriate distance.