# Number of Lakes in the World

The world has 307 million lakes, according to calculations made by an international team of scientists. That number includes all natural lakes, but not human-made lakes such as reservoirs formed by dams.

The lake count takes in ponds as small as one-tenth of a hectare (one-quarter acre). In fact, most lakes on earth are small, with nine out of ten lakes covering less than one hectare (2.5 acres).

The world's largest lake is the Caspian Sea, which extends over 378,119 square kilometres (145,993 square miles), an area about the size of Montana or Germany. The Caspian Sea is in a league of its own as no other lake tops 100,000 square kilometres in area.

Altogether, these natural bodies of freshwater cover 4.2 million square kilometres (1.62 million square miles) of the earth's surface. That's an area equivalent to more than half the size of the contiguous United States and makes up 2.8 percent of the earth's continents.

## How Many Lakes on Earth?

 304 million Lakes in the world at least 0.1 hectares (one-quarter acre) in area 27 million Lakes one hectare (2.5 acres) or greater in size 17 Lakes larger than 10,000 sq km (3,861 sq miles) 1 Lake over 100,000 sq km (38,610 sq miles)

The world's 17 largest lakes take up nearly a million square kilometres, or one-quarter of the planet's total lake area. At the other end of the size spectrum, the world's smallest lakes, those less than one hectare (2.5 acres), are so numerous, they add up to 692,000 square kilometres (267,183 square miles) of the earth's surface, an area about the size of Texas.

To estimate the number and area of the world's lakes, scientists from United States, Canada, Spain, Netherlands, Sweden and Finland analyzed data from fine-resolution geographical information systems (GIS). They then ran data through mathematical equations of the relationships between lake densities and lake area within a region.

##### Reference

John A. Downing, Yves T. Prairie, Jonathan J. Cole, Carlos M. Duarte, Lars Tranvik, Robert Striegl, William H. McDowell, Pirkko Kortelainen, Nina Caraco, John M. Melack and Jack Middelburg. 2006. The global abundance and size distribution of lakes, ponds, and impoundments. Limnology and Oceanography. 51(5): 2388-2397.