A tonne of gravel contains around 18 cubic feet. One cubic yard, or approximately 27 cubic feet, represents one and a half tonnes of gravel. When dumped 2 inches deep, one tonne of gravel covers around 80 to 100 square feet.
A cubic yard measures three feet length, three feet wide, and three feet tall. Although loose gravel is normally supplied by the cubic foot, knowing the square feet of the area to be covered can assist establish the number of tonnes required. Square footage is calculated by calculating the length of the area by the width of the area and then multiplying by 100 to get an estimate of how many tonnes of gravel are required.