Freshwater Habitats Trust) have defined a pond to be 'a man-made or natural waterbody that is between 1 m² (0.00010 hectares; 0.00025 acres) and 20,000 m² (2.0 hectares; 4.9 acres) in area, which holds water for four months of the year or more.' Other European biologists have set the upper size limit at 5 hectares (50,000 m²; 12 acres).

In North America, even larger bodies of water have been called ponds; for example, Crystal Lake