# Find the volume contained in a surface

Use the Area And Volume Statistics tool to calculate 2D area, surface area, and volume. All are relative to a given reference plane.

The 2D area of a rectangular patch of surface model is its length times its width. The surface area is measured along the slope of the surface; it takes the variation in the height of the surface into account. Unless the surface is flat, the surface area will always be greater than the 2D area. You can compare the values for the 2D area and surface area to get an indication of the roughness or slope of the surface—the larger the difference between the values, the rougher or steeper the surface.

The volume is the space (in cubic map units) between the surface and a reference plane set at a particular height. You can determine the volume above the plane or below it so you can answer questions such as, How much material is between the 1,200-foot contour and the top of this hill? or How much water could be stored in this reservoir if the top of the dam will be at 300 meters?