How much fill dirt do I need?
Work out the volume of the space in cubic yards (length × width × depth in feet ÷ 27), then add a compaction allowance, because loose fill shrinks when it is packed down. A 20 × 10 ft area raised 6 inches is 3.7 cubic yards; with a 25% allowance, order about 4.6 cubic yards.
Formula
Space to fill (yd³) = length (ft) × width (ft) × depth (ft) ÷ 27
Loose fill to order (yd³) = space to fill × (1 + compaction allowance)
1 cubic yard = 27 cubic feet (3 ft × 3 ft × 3 ft)
Worked example
20 ft × 10 ft, 6 in deep
- Find the area: 20 ft × 10 ft = 200 sq ft.
- Convert the depth to feet: 6 in ÷ 12 = 0.5 ft.
- Multiply by the depth: 200 sq ft × 0.5 ft = 100 cubic feet.
- Divide by 27: 100 ÷ 27 = 3.7 cubic yards.
- Add the 25% compaction allowance: 3.7 × 1.25 = 4.63 cubic yards of loose fill to order.
Bank, loose and compacted cubic yards
Soil changes volume as it is handled. Undisturbed soil in the ground is measured in bank cubic yards. Digging and loading loosens it, so the same soil takes up more room in a truck: loose cubic yards. Compacting it in place squeezes it below even its bank volume.
Fill dirt is delivered loose. To end up with a measured, compacted space filled, you need more loose cubic yards than the space measures. The table shows standard conversion factors from the U.S. Army's earthmoving manual, relative to 1 bank cubic yard.
Choosing a compaction allowance
If you will compact the fill in layers with a plate compactor or roller, use the figure for your soil from the table: about 17% for sand or gravel, 39% for loam (common earth) and 59% for clay.
Fill that is only dumped and shaped still settles. USDA conservation standards for earth dikes allow at least 15% of the fill height for settlement of dumped-and-shaped fill.
The calculator starts at 25%, between those two cases. Choose the allowance that matches your soil and how you will compact it.
Filling a hole or trench
Use the rectangle for a trench or a square hole, and the circle for a round hole such as an old tree pit or post hole. Measure the depth of a hole in feet or inches from the bottom up to the finished grade. For an irregular low spot, measure the average depth at several points.
Frequently asked questions
What is a compaction factor?
It is how much more loose soil you need to end up with a compacted volume. A 25% allowance means ordering 1.25 cubic yards of loose fill for every cubic yard of space to fill.
How many cubic yards of fill dirt for a 10 × 10 ft area 1 foot deep?
10 × 10 × 1 = 100 cubic feet, and 100 ÷ 27 = 3.7 cubic yards of space. With a 25% compaction allowance, that is about 4.6 cubic yards of loose fill.
Fill dirt or topsoil?
Fill dirt is for building up grade, leveling and filling holes. For the top layer where grass or plants will grow, use topsoil or a garden blend over the fill.
How many cubic feet are in a cubic yard of fill dirt?
27, the same as any cubic yard: 3 ft × 3 ft × 3 ft. The compaction allowance is added to the number of cubic yards you order, not to the size of a yard.
Order by the cubic yard
Soil Direct delivers bulk landscape materials by the cubic yard from local suppliers. Enter your address to see delivered prices.
Link to or cite this page
Teachers, writers, landscapers and anyone else are welcome to link to or cite this page. Please credit Soil Direct.
Citation
Soil Direct. "Fill Dirt Calculator." soildirect.com, 2026. https://soildirect.com/calculator/fill-dirt-calculator/
Link HTML
Fill Dirt Calculator by <a href="https://soildirect.com/calculator/fill-dirt-calculator/">Soil Direct</a>