The Great Lakes are the largest lakes in the United States by volume. These five lakes are so massive that they can be seen from space! Lake Michigan is the second largest of the Great Lakes by volume, behind only Lake Superior. This article explores how many gallons of water are in Lake Michigan and how it compares to other lakes.
How Many Gallons of Water Are in Lake Michigan?

Lake Michigan and Lake Huron meet at the Straits of Mackinac. The Mackinac Bridge spans the straits.
©Laurent Fady/iStock via Getty Images
Lake Michigan is 1,183 cubic miles in volume. That converts to a whopping 1.3 quadrillion gallons! The total number is 1,302,621,565,631,468 gallons. Such a massive number can be difficult to picture. Here is an example. The average person lives for 79 years, which is 4,119 weeks. If this popular lake was made of milk, it could provide one gallon of milk per week to 316 billion people for their entire lives.
Let’s explore how its volume in gallons and cubic miles compares to other lakes.
Compared to Other Lakes

There are 1.3 quadrillion gallons of water in Lake Michigan.
©Better Planet Media/iStock via Getty Images
The largest lakes by volume in the U.S. are the Great Lakes, followed by Lake Tahoe and Lake Iliamna. Lake Superior is the largest lake in the U.S. by volume at 2,900 cubic miles. That converts to 3.2 quadrillion gallons. Therefore, Lake Superior contains 1.9 trillion more gallons of water than Lake Michigan!
On the other hand, Lakes Huron, Ontario, and Erie are all smaller than Lake Michigan. Let’s see how their size in gallons compares. Lake Huron is 845 cubic miles, which converts to 930 trillion gallons. That’s 370 trillion fewer gallons of water than Lake Michigan. Below, we list the volume of the other Great Lakes.
Ontario: 391 cubic miles, 431 trillion gallons
Erie: 117 cubic miles, 128 trillion gallons
Tahoe: 36 cubic miles, 38 trillion gallons
Iliamna: 28 cubic miles, 31 trillion gallons
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