How this calculator works
The volume of the dig is the area times the depth, converted to cubic yards by dividing cubic feet by 27. Soil does not stay the same size when it is dug: it breaks up and swells, so the pile is bigger than the hole. The swell is about 12% for sand, 25% for topsoil and 30% for clay. Truck loads are the loose volume divided by the truck's capacity, and the weight is the in-ground volume times the tons per cubic yard of the soil.
Worked example: a 20 × 10 ft hole 3 feet deep is 600 cubic feet, which is 22.22 cubic yards in the ground. Topsoil swells by 25%, so the pile is 27.78 cubic yards, which weighs about 24.4 tons and takes 3 load of a 10 yard tandem dump truck, or 19 loads of a pickup or trailer. In clay the pile would be 28.89 cubic yards. A round hole 12 ft across and 3 ft deep is 12.57 cubic yards, and 12 post holes of 12 inches by 3½ feet are 1.22 cubic yards.
Soil to dig for common jobs
Topsoil or loam, tandem dump truck of 10 cubic yards.
| Dig | In the ground | Loose | Truck loads | Tons |
|---|---|---|---|---|
| 10 × 10 × 3 ft | 11.1 yd³ | 13.9 yd³ | 2 | 12.2 |
| 20 × 10 × 3 ft | 22.2 yd³ | 27.8 yd³ | 3 | 24.4 |
| 20 × 12 × 4 ft | 35.6 yd³ | 44.4 yd³ | 5 | 39.1 |
| 30 × 15 × 4 ft | 66.7 yd³ | 83.3 yd³ | 9 | 73.3 |
| 40 × 20 × 6 ft | 177.8 yd³ | 222.2 yd³ | 23 | 195.6 |
| 50 × 30 × 8 ft | 444.4 yd³ | 555.6 yd³ | 56 | 488.9 |
Tips before you buy
- Measure the hole at its full size, including the room for forms, drainage stone and working space, usually 1 to 2 feet more on each side than the finished foundation.
- Keep topsoil separate from the subsoil. You will want it for the final grading.
- Leave room to dump the soil on site if you can, since hauling and disposal usually cost more than the digging.
- Wet soil weighs more and is harder to dig and haul. Digging after rain is slower and messier.
- Call 811 before you dig, and ask your building department about permits for deeper excavations, which may need shoring.
Tools & materials for this project
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Frequently asked questions
How many cubic yards of dirt will I dig?
Length × width × depth in feet, divided by 27. A 20 × 10 ft hole 3 feet deep is 22.22 cubic yards in the ground.
What is the swell factor of soil?
Soil swells when it is dug: about 12% for sand, 15% for gravel, 25% for topsoil and 30% for clay. 22.22 yards in the ground becomes 27.78 yards of topsoil, or 28.89 yards of clay.
How many truck loads of dirt is that?
3 load of a 10 cubic yard tandem dump truck for 27.8 loose cubic yards. A pickup or trailer carries about 1½ yards, so 19 loads.
How much does excavated dirt weigh?
About 1.1 tons per cubic yard for topsoil, more for clay (1.4) and sand (1.4). The 22.2 yards of topsoil weigh about 24.4 tons.
How much fill do I need to put it back?
About 10% more than the hole: 24.44 cubic yards for this one, because loose fill has to be compacted.
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Estimates only. Results assume standard materials and simple shapes. Supplier products vary, and the final call on quantity, structure and safety is yours. Check your local code and your supplier's guidance before ordering.