What is a good size pool? For a family of 8 people, a pool size of 18 by 36 feet is adequate. Even if you all decide to swim at the same time, there will be enough space for everyone. A rectangular shape is the best choice for this size of the pool. If there are six or less in your family, a pool size of 16 by 32 feet will be sufficient. For more information about swimming pool sizes give Allied Aquatics a call today! Let us be your Frisco / McKinney Pool Service!