How the sloped area calculator works
Ground that rises or falls needs fill that is deeper in one place than another, and the average depth gives the right volume when the slope is steady.
Use this cubic yard calculator for a sloped area to get cubic yards, cubic feet, cubic meters, and a cost estimate in one step.
The calculator multiplies out the volume in cubic feet, then divides by 27, because a cubic yard is a cube that is 3 feet on each side. For this shape the formula is shown below in words and symbols.
In plain words: length times width times the average depth, then divide by 27 if your answer is in cubic feet. Mixed units are fine. Pick feet, inches, yards, meters, or centimeters next to each box and the tool converts them for you.
Worked example for a sloped area
Take a sloped area with length 20 ft, width 10 ft, depth at shallow end 2 in, depth at deep end 6 in. The volume works out to 66.67 cubic feet. Divide by 27 and you get 2.47 cubic yards. With 10 percent extra for waste, order about 2.72 cubic yards.
Measuring a sloped area
Measure the depth of fill needed at the shallow end and the deep end. If the slope is not steady, split the area into sections.
Common uses for the sloped area calculator
- Leveling a yard that slopes
- Building up a low corner
- Grading a driveway or pad
- Filling behind a retaining wall
Sloped Area volume at different sizes
The table scales the example above so you can see how fast volume grows. Doubling the depth doubles the volume. Doubling every length quadruples the area, and with the same depth the volume quadruples too.
| Size | Cubic feet | Cubic yards | With 10 percent extra |
|---|---|---|---|
| 10 ft by 5 ft by 2 in by 6 in | 16.67 | 0.62 | 0.68 |
| 20 ft by 10 ft by 2 in by 6 in | 66.67 | 2.47 | 2.72 |
| 30 ft by 15 ft by 2 in by 6 in | 150.00 | 5.56 | 6.11 |
| 40 ft by 20 ft by 2 in by 6 in | 266.67 | 9.88 | 10.86 |
| 60 ft by 30 ft by 2 in by 6 in | 600.00 | 22.22 | 24.44 |
| 20 ft by 10 ft by 4 in by 12 in | 133.33 | 4.94 | 5.43 |
| 40 ft by 20 ft by 4 in by 12 in | 533.33 | 19.75 | 21.73 |
What the 2.47 cubic yard example weighs
Volume is only half of the story when a truck is hauling the load. The table shows planning weights for the example volume in several materials.
| Material | US tons | Pounds |
|---|---|---|
| Topsoil | 2.72 | 5,432 |
| Mulch | 0.86 | 1,728 |
| Gravel | 3.46 | 6,914 |
| Sand | 3.33 | 6,667 |
| Concrete | 5.00 | 10,000 |
| Compost | 1.23 | 2,469 |
These figures are planning estimates. Real material varies in moisture, size, and compaction, so confirm weights and order quantities with your supplier.
Frequently asked questions
How do I calculate cubic yards for a sloped area?
Find the volume in cubic feet, then divide by 27. For this shape: length times width times the average depth. Convert inches to feet first by dividing by 12.
How many cubic yards is the example sloped area?
Length 20 ft, width 10 ft, depth at shallow end 2 in, depth at deep end 6 in comes to 2.47 cubic yards, or 66.67 cubic feet.
How much extra should I order?
Most people add 5 to 10 percent for waste, and 10 to 15 percent for rough ground or loose material.
Can I use metric units?
Yes. Choose meters or centimeters next to any length. The result still shows cubic yards, and the cubic meter figure sits beside it.
Why does the answer change with the material?
The volume does not change, but weight and bag counts do, because each material has a different density.