Waterbed Mattress Volume: Calculation & Dimensions

The volume of a rectangular prism is calculated by multiplying the length, width, and height of the prism. In this case, the length is 7 feet, the width is 4 feet, and the height is 1 foot. So, the volume of the waterbed mattress is 7 x 4 x 1 = 28 cubic feet.

Therefore, the volume of the waterbed mattress is 28 cubic feet.