About the Dirt Volume Calculator
Not every earthworks job is a flat area of even depth. You might need to know how much soil comes out of a hole for a pond or a basement, what a spoil pile on site amounts to, or how much dirt it takes to build a berm along a property line. These shapes each have their own volume formula, and dirt changes volume when it is dug, so the in-ground figure and the truckload figure differ.
This dirt volume calculator works out the volume of a rectangular pit or trench, a round hole, a cone-shaped pile or a triangular berm, all from dimensions in feet. It gives the result in cubic feet, cubic yards and cubic metres, and applies a swell factor to show how many loose yards an excavation will produce, or how much a loose pile will occupy once compacted.
How to Use the Dirt Volume Calculator
Choose the shape.
Enter the length and width for a pit or berm, or the diameter for a hole or pile.
Enter the depth or height in feet and the swell factor.
The Formulas
rectangular pit or trench = length × width × depth
round hole = π × radius² × depth
cone-shaped pile = π × radius² × height ÷ 3
berm (triangular ridge) = length × base width × height ÷ 2
cubic yards = cubic feet ÷ 27
loose yards = bank yards × (1 + swell)Step-by-Step Examples
A pit 10 ft long, 8 ft wide and 6 ft deep, with 25% swell.
volume 10 × 8 × 6 = 480 ft³ = 17.78 bank yd³
loose 17.78 × 1.25 = 22.22 yd³ → 3 truckloads of 10 yd³A pile 10 ft across and 6 ft high.
volume π × 5² × 6 ÷ 3 = 157 ft³ = 5.82 yd³A berm 40 ft long, 8 ft wide at the base and 3 ft high.
volume 40 × 8 × 3 ÷ 2 = 480 ft³ = 17.78 yd³Bank, Loose and Compacted Yards
Earthmoving uses three different volumes for the same soil. Bank volume is soil undisturbed in the ground. Loose volume is soil after digging, when air has worked in between the clods, and it is larger. Compacted volume is soil after rolling, usually a little smaller than bank. An excavator measures a hole in bank yards, but the trucks hauling the spoil away carry loose yards, so you need more truckloads than the hole's volume suggests.
Typical Swell Factors
Swell depends on the material. Clean sand and gravel swell about 10 to 15%, because their grains pack loosely in the ground already. Common earth or loam swells about 20 to 30%. Clay swells 30 to 40%, and blasted rock can swell 50% or more. The calculator uses 25% by default, suitable for most mixed soils. For a pile or berm of loose dirt, the calculator works the other way, showing how much in-place volume that loose material represents.
Piles and Berms in Practice
Real piles are rarely perfect cones. A pile dumped from a truck is often longer than it is wide; in that case measure its average diameter, or treat it as a berm using its length, base width and height. A berm built for screening or drainage usually has side slopes of about 2:1 or flatter, so its base width is roughly four times its height plus the width of any flat top. A flat top adds volume: add the top width × height × length to the triangular figure.
Planning Excavation
Knowing the loose volume tells you how many truckloads to book and where to stockpile spoil you want to reuse. If you plan to backfill some of it, keep that portion on site, and remember that the backfill will be compacted back down to less than the loose volume. Excavation near foundations, utilities and property lines needs care: call the utility locating service before you dig.
Irregular Holes
For a hole with sloping sides, such as a pond or a pit cut back for safety, the volume is less than a box of the top dimensions. A good approximation is to average the area at the top and the area at the bottom, then multiply by the depth. For example, a pond 20 × 15 ft at the top and 10 × 5 ft at the bottom, 4 ft deep, averages (300 + 50) ÷ 2 = 175 square feet, about 700 cubic feet. Enter the average length and width as a pit to get a close figure.
Trenches
A trench is simply a long, narrow pit. Enter its length, width and depth in feet. A trench 100 feet long, 2 feet wide and 3 feet deep holds 600 cubic feet, 22.2 bank yards, which becomes about 28 loose yards once dug. If a pipe goes in, subtract the pipe volume from the backfill, and remember that pipe bedding stone is ordered separately.
Safety in Excavations
Trenches and pits deeper than about 5 feet can collapse without warning, and a cubic yard of soil weighs over a ton. Slope the sides back, shore them, or use a trench box, and keep spoil piles at least 2 feet from the edge.
Understanding Your Result
The headline gives the volume in cubic yards.
The working line shows the formula, cubic feet and cubic metres.
The loose dirt line gives the loose yards to haul away, or for piles and berms the in-place equivalent.
When Should You Use This Calculator?
Use it to estimate spoil from a hole, pond or trench.
Use it to measure a dirt pile before selling, moving or spreading it.
Use it to plan the soil for a berm.
Common Mistakes
Booking trucks by bank yards. Dug soil swells.
Treating a pile as a box. A cone holds a third of its cylinder.
Forgetting a berm's flat top. Add it to the triangular volume.
Digging without locating utilities. Call before you dig.