What Is Grain Gravel?

Grain

• Grain refers to the size of the stones used for gravel. Specifically, it is the diameter of an individual stone. Gravel is divided into different grain categories because different grades are used for different applications.

Categories

• Gravel grain sizes are broken down into very course, course, medium, fine and very fine. Boulders and cobble are too big to be considered gravel. Clay, silt and sand are too small and are in their own categories.

Sizes

• There are several different gravel sizes. Very course gravel is between 1.26 and 3 inches (32 to 79.2 mm). Course gravel is .63 to 1.26 inches (16 to 32 mm) in diameter. Medium gravel is .31 to .63 inches (8 to 16 mm) across. Fine gravel is .157 to .31 inches (4 to 8 mm) and very fine is .079 to .157 inches (2 to 4 mm) in diameter.

Uses

• Course gravel can be found on gravel patios and driveways. You can also use this type of gravel in garden beds and for drainage. Medium-sized gravel is used to help prevent erosion of the dirt below and can also be used in drainage systems. Smaller gravel is found in gardens and lawns as accent points, as well as the foundation for walkways. Gravel can also be mixed with cement to make sidewalks and walls that have a rough texture.