Calculating cubic yards takes three measurements and one division. Once you know the steps, you can size any project, from a flower bed to a full driveway.
The basic formula
A cubic yard measures volume: 3 feet long, 3 feet wide, and 3 feet deep. That is 27 cubic feet, so every calculation ends by dividing cubic feet by 27.
For a rectangle, the formula is length times width times depth, all in feet, divided by 27. If your depth is in inches, divide it by 12 first to get feet.
Step by step
First, measure the length and width of the area in feet. Second, decide on a depth and convert it to feet: 3 inches is 0.25 feet, 4 inches is 0.333 feet, and 6 inches is 0.5 feet. Third, multiply the three numbers to get cubic feet. Fourth, divide by 27.
Example: a bed that measures 20 feet by 10 feet, covered 3 inches deep, holds 20 × 10 × 0.25 = 50 cubic feet. Divide by 27 and you get 1.85 cubic yards.
Other shapes
Circles use pi times the radius squared times the depth. Triangles use half of base times height times depth. Piles use one third of pi times radius squared times height. For odd shapes, break the area into simple pieces, or find the total area and multiply by an average depth.
Our calculator handles every shape, so you only enter the measurements.
Add extra for waste
Real jobs use more than the exact number. Uneven ground, settling, spillage, and compaction all take material. Many people add 5 to 10 percent for concrete and mulch, and 10 to 20 percent for loose fill and base stone.
Frequently asked questions
How many cubic feet are in a cubic yard?
There are 27 cubic feet in one cubic yard, because 3 feet times 3 feet times 3 feet equals 27.
How do I convert inches of depth to feet?
Divide the inches by 12. Three inches is 0.25 feet, and six inches is 0.5 feet.
Do I need to round up?
Yes. Round up to the next quarter or half yard, because suppliers rarely sell smaller amounts and running short costs more than a small surplus.