Excavation Calculator
Bank volume = length × width × depth, ÷ 27 for cubic yards; the loose volume to haul = bank volume × (1 + swell %). A 10 × 8 ft footing cut 2 ft deep is 160 ft³, or 5.93 yd³ in the ground and 7.41 yd³ loose at the default 25% swell. See the Cubic Yard Calculator.
How it's calculated: Bank volume = length × width × depth; loose volume = bank volume × (1 + swell %); weight = bank volume × the selected soil's in-situ density.
Result appears here
Fill in the fields and press Calculate.
Formula, calculation, assumptions and sources
Bank volume = Length × Width × Depth
Loose (swollen) volume = Bank volume × (1 + swell %)
Weight = Bank volume × in-situ soil density (weight does not change with swell)
Run the calculation to see each step with your own numbers.
A 10 ft × 8 ft footing excavation, 2 ft deep, common earth, default 25% swell.
Bank volume = 10 × 8 × 2 = 160 ft³ = 5.93 yd³ exact
Loose volume = 5.93 × 1.25 = 7.41 yd³ (what to size the truck/dumpster for)
Weight ≈ 4.53 m³ × 1,600 kg/m³ = 7,250 kg ≈ 8.0 US tons
- A rectangular, uniform-depth cut. A sloped/benched excavation (required by OSHA for most trenches over 5 ft) needs extra volume for the side slopes — not modelled here.
- Swell percentages are typical ranges; actual bulking depends on moisture, compaction history and handling equipment.
- Weight uses the soil's in-situ (undisturbed) bulk density and does not change when the soil is loosened — only the volume grows.
- Groundwater, shoring, rock breaking and haul distance are not included.
- Why is the 'recommended' volume bigger, not smaller?
- Unlike most BuildNumerics calculators, where 'recommended' means extra material to buy, here it means the soil physically expands once dug up — loose soil takes up more room than it did packed in the ground. Size your truck or dumpster to the recommended (loose) figure, not the bank figure.
- Does the weight change once the soil is loosened?
- No — swelling only increases volume (the soil gets fluffier/less dense), the total mass stays the same. That's why the weight output doesn't get a waste-adjusted figure.
- What about a sloped trench or bench?
- OSHA generally requires sloping or benching for trenches deeper than 5 ft in most soil. That adds volume beyond a straight-sided box — treat this as the minimum, and add extra for the slope if one is required.
- How do I calculate excavation volume in cubic yards?
- Multiply length × width × depth in feet and divide by 27. A 10 × 8 ft cut, 2 ft deep, is 160 ft³, or 5.93 yd³ measured in the ground. Multiply by 1 plus the swell percentage for the loose volume — 7.41 yd³ at 25%.
- How much dirt comes out of a 100 ft trench?
- A trench 100 ft long, 2 ft wide and 3 ft deep holds 600 ft³, or 22.22 yd³ in the ground. Dug out at the default 25% swell it becomes about 27.78 yd³ of loose soil to haul or stockpile. Enter your own swell percentage if your soil differs.
Geometry
Standard geometry: Volume = L × W × D.
Soil swell (bulking) percentages
Typical ranges by soil type (topsoil/common earth ≈25%, sand & gravel ≈15%, dense clay ≈35%, blasted rock ≈50–60%): Caterpillar Performance Handbook earthwork tables; USACE construction-estimating references. Actual bulking varies with moisture and handling.
In-situ density
Typical in-situ bulk densities by soil type: Engineering ToolBox 'Densities of common materials'; USDA soil bulk-density reference ranges.
About the Excavation Calculator
The Excavation Calculator gives the bank (in-situ, undisturbed) volume you're digging out of a footing, trench, pool or pad, and — because dug soil loosens and takes up more room than it did in the ground — the larger swollen volume you'll actually need to haul or stockpile. Weight is estimated from the selected soil's in-situ density, which does not change with swell (the mass is the same; only the volume grows). For fill you're bringing in rather than removing, use the Topsoil, Gravel or Cubic Yard calculators instead.
What you enter
- Length
- Width
- Depth — Measured from existing grade to the bottom of the cut.
- Soil type — Sets the default swell allowance and density below — both editable.
- Waste allowance — Default 25%. Adjust to your own allowance — the exact figure is always shown too.
What you get back
- Excavation volume (bank, in-situ) — Recommended = swell-adjusted loose/hauled volume, not extra material to buy.
- Estimated in-situ weight — Mass doesn't change when soil swells — only its volume does.
The formula, a worked example, the assumptions behind it and the sources are shown in full below the calculator.
Related calculators
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- Gravel Calculator — Gravel by volume and by delivered weight for driveways, paths and fill.
- Cubic Yard Calculator — Convert a length, width and depth into cubic yards, cubic feet or cubic metres.
- Plastering Calculator — Plaster (render) volume, plus cement bags and sand, for a wall or ceiling area from its thickness and mix ratio.
- Bituminous Prime & Tack Coat Calculator — Bituminous prime coat or tack coat material for a paved area from its application rate.
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Part of the Landscaping & Driveway calculators.