Excavation Calculator
Work out how much dirt a pit, trench or hole removes, in bank and loose cubic yards, with sloped sides, the swell of each soil type, its weight, and the truckloads to haul it.
How to Use
- Pick a rectangle (basement, pool, trench) or a round hole.
- Enter the size of the bottom of the dig and its depth.
- If the sides are cut back for safety, enter the side slope as horizontal feet per foot of depth (1 for a 1:1 slope); 0 means straight sides.
- Choose the soil. It sets how much the dirt swells once dug and how much it weighs.
- Enter what a truck carries, by volume and by weight, to get the number of loads.
Worked Example
A basement 40 × 30 ft and 8 ft deep, with straight sides, in common earth. Volume = 40 × 30 × 8 = 9,600 ft³, and 9,600 ÷ 27 = 355.6 bank yd³. Common earth swells about 25% once dug, so there are 355.6 × 1.25 = 444.4 loose yd³ to haul. In 10 yd³ trucks that is 45 loads. At about 2,550 lb per bank yard the dirt weighs 453 tons, about 10 tons a load, inside a 13-ton payload.
The same basement with 1:1 sloped sides. The top of the dig grows to 56 × 46 ft. By the prismoidal formula, V = D ÷ 6 × (bottom + 4 × middle + top) = 8 ÷ 6 × (1,200 + 4 × 1,824 + 2,576) = 14,763 ft³, or 546.8 bank yd³: 54% more dirt than the straight-sided hole.
The common mistake: ordering trucks by bank yards. 355.6 yd³ is the hole, not the pile. Planning 36 loads for the basement leaves about 9 loads of dirt behind.
Show Work
Formulas
Bank, Loose and Compacted
Earthmovers measure soil in three states. Bank volume is soil undisturbed in the ground. Digging breaks it up and lets air in, so the same soil as a loose pile is larger by the swell factor. Spread and compacted as fill, it shrinks again, often below its bank volume: common earth compacted as fill takes up about 90% of its bank volume. That is why a project that “balances” cut and fill on paper still needs the swell and shrink factors.
Trench safety is not optional. Cave-ins kill workers every year, and a cubic yard of soil weighs more than a car. Below 5 ft, US rules require sloping, benching or a trench box, unless the trench is in stable rock, and a competent person must inspect the dig daily.
About This Calculator
This calculator finds the volume of a rectangular pit, trench or round hole, including sloped sides, then the loose volume after swell, the weight for the soil type you choose, and the number of truckloads, counting whichever runs out first: the truck’s volume or its legal payload. It works in feet and US tons or metres and tonnes.
Everything runs in your browser; nothing is sent anywhere. Swell and weight figures are typical values; site soils vary, and moisture changes both.
Related calculators: Concrete Calculator, Gravel Calculator, and Pool Volume Calculator.
Frequently Asked Questions
What are bank and loose cubic yards?
Bank yards measure the soil as it sits undisturbed in the ground. Once dug, it breaks up and takes more room: loose yards. Hauling and dumping are priced on loose volume; the hole itself is measured in bank yards. Common earth swells about 25%, so 100 bank yards becomes about 125 loose yards.
What is the swell factor of soil?
Typical figures: sand and gravel about 12%, common earth or loam about 25%, clay and topsoil about 35%, and blasted rock 50–65%. Wet or sticky material swells more. The figure varies on every site, so treat it as an estimate.
Why slope the sides of an excavation?
Vertical walls in soil can collapse without warning. In the US, OSHA requires trenches 5 ft or deeper to be sloped, benched or shored, with slopes from 3/4:1 in stiff clay to 1½:1 in sand. Sloping makes the dig much larger at the top: a 40×30 ft basement 8 ft deep with 1:1 sides removes 54% more dirt than one with vertical walls.
How many cubic yards does a dump truck carry?
A single-axle dump truck carries about 5 to 6 yd³, a tandem about 10 to 14 yd³, and a tri-axle up to about 16 yd³. Heavy soil often fills a truck by weight before volume: a tandem rated for 13 tons holds only about 9 yd³ of wet clay.
How much does a cubic yard of dirt weigh?
In the ground, roughly 2,300 lb for topsoil, 2,550 lb for common earth, 2,700 lb for sand, 2,950 lb for clay and 3,000 lb for gravel per bank yard. Water adds a lot: saturated soil can be 10–20% heavier.
How do I use the Excavation Calculator?
Just type your numbers. The answer shows up right away — there is no button to press. Change anything and it updates by itself.
Is it free? Does it work without internet?
Yes to both. It is free with no sign-up, and once the page has loaded it keeps working even with no internet.
Where does my data go?
Nowhere — every calculation runs on your own device. Nothing you enter is uploaded, logged, or stored.
Common Use Cases
Basement dig
A 40×30 ft basement 8 ft deep is 355.6 bank yd³; in common earth that is 444 loose yd³, or 45 loads of 10 yd³.
Sloped basement
The same basement with 1:1 sides is 546.8 bank yd³, because the top of the dig is 56×46 ft.
Utility trench
A trench 100 ft long, 2 ft wide and 4 ft deep is 29.6 bank yd³: four 10 yd³ truckloads once loose.
Pond
A 30 ft round pond 6 ft deep at the bottom edge, with 2:1 sides, is 316.3 bank yd³ of clay: about 427 yd³ loose.
Footing trench
A 24 in wide, 3 ft deep footing trench around a 30×40 ft house (140 ft) is 31.1 bank yd³.
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