If you are building a driveway, sidewalk or pond, gravel will likely play a role in the construction. You will likely calculate the volume of the area you need to fill to determine the amount of gravel you need, but some suppliers sell gravel by weight rather than volume. In that case, calculate the weight per cubic yard of gravel and multiply by the volume you need to determine what weight of gravel to order.

Approximate the specific weight of your gravel based on the particle size. Gravel ranges from 85 to 125 lb. per cubic foot. Gravel with high percentages of small particles will have a higher specific weight, while gravel with high percentages of large particles will have a lower specific weight. You can use an average specific weight of 100 lb. per cubic foot in most cases.

Set up a unit conversion to convert from pounds per cubic foot to pounds per cubic yard. There are 27 cubic feet in a cubic yard, so for gravel with a specific weight of 100 lb. per cubic foot, use 100 lb. per cubic foot times 27 cubic feet per cubic yard.

Multiply the unit conversion to find the weight per cubic yard. For example, 100 lb. per cubic foot times 27 cubic feet per cubic yard equals 2,700 lb. per cubic yard. Cubic feet "disappears" from the result because, if you wrote the units in fraction form, cubic feet would appear in the denominator of pounds per cubic foot and in the numerator of cubic feet per cubic yard. This means the cubic feet cancel out when you multiply. In this example, if the gravel had a specific weight of 85 lb. per cubic foot, then 85 lb. per cubic foot times 27 cubic feet per cubic yard equals 2,295 lb. per cubic yard.