Trench Excavation Calculator
Estimate neat and waste-adjusted trench excavation volume from length, width, and depth. Use it for utility trenches, footings, and cut checks before calling trucks.
Enter your values, then press Calculate.
How to calculate
Enter trench length, excavated width, and depth. Width is the trench cut, not the pipe OD. Depth is from existing grade to trench bottom. Add waste for sloughing and over-dig.
Formula
Volume (ft³) = length (ft) × width (ft) × depth (ft). Cubic yards = ft³ ÷ 27. Waste multiplies the neat volume for over-excavation and irregular trench walls.
Common use cases
- Utility and storm trench takeoffs
- Footing excavation
- Checking truck counts against a cut
- Comparing 18 in vs 24 in trench widths
Assumptions
- Width is excavated width: pipe OD plus bedding clearance and worker room, not the nominal pipe size.
- Depth is average cut from existing grade to trench bottom, not cover over the pipe.
- Result is in-place bank cubic yards. Swell is a different calculator.
- Waste is extra cut (slough, over-excavation), not a soil swell percent.
Limitations
- Rectangular trench only. Does not cut a sloped side-slope prism.
- Does not deduct the pipe or separate the bedding layer.
- Does not convert bank yards to loose haul yards or truckloads.
- Does not apply OSHA width or shoring rules.
Worked examples
100 ft of 24 in wide trench 4 ft deep
24 in is excavated width, not an 18 in pipe. 100 × 2 ft × 4 ft ÷ 27 = 29.63 bank yd³. That number still needs swell before you call trucks.
1. Neat volume in cubic feet
100 ft × 2 ft × 4 ft = 800 ft³
2. Convert to cubic yards
800 ft³ ÷ 27 = 29.6296 yd³
3. Apply waste
29.6296 × (1 + 0%) = 29.6296 yd³
10% waste
1. Neat volume in cubic feet
100 ft × 2 ft × 4 ft = 800 ft³
2. Convert to cubic yards
800 ft³ ÷ 27 = 29.6296 yd³
3. Apply waste
29.6296 × (1 + 10%) = 32.5926 yd³
Bank yards of the cut, not bedding or backfill
This calculator is the rectangular prism of the excavated trench: length × width × depth, converted to cubic yards (÷ 27). Width is excavated width, including clearance and worker room, not the pipe outside diameter. The result is in-place bank yards. It does not swell the material, does not deduct the pipe, and does not isolate the bedding layer. Open trench spoils after this page for loose haul yards; open bedding or backfill for those layers.
Waste on a trench cut
Waste here is extra cut from over-excavation, slough, and irregular bottom — not a swell factor. 10% on a 100 ft × 24 in × 4 ft trench is 29.63 cy bank plus 2.96 cy waste = 32.59 cy. If the inspector pays neat-line only, leave waste at 0 and keep the over-excavation on a separate line.
Utility trench versus footing trench
A 100 ft sewer lateral 24 in wide and 4 ft deep is 24.69 bank yd³ before waste (100 × 2 × 4 ÷ 27). A spread footing of the same length is the same arithmetic if you measure excavated width and depth. What changes is the next page: utilities usually need bedding and a pipe deduction on backfill; footings usually do not. Keep this result as bank yards on the bid form, then open trench spoils if you are hauling.
Related calculators
- Trench Spoils CalculatorConvert bank trench yards to loose spoils and truckloads using a swell factor.
- Bedding CalculatorEstimate pipe bedding cubic yards from length, width, and depth.
- Backfill CalculatorEstimate trench backfill cubic yards after subtracting pipe displacement.
- Pipe Slope CalculatorConvert elevation drop and run into percent grade, ratio, and inches per foot.
- Pipe Volume CalculatorCalculate internal volume of a circular pipe in cubic feet and gallons.
FAQ
Is trench width the pipe diameter?
No. Use the excavated width, which is usually the pipe OD plus bedding clearance and worker room, not the nominal pipe size.
Does this include spoils swell?
No. This is in-place bank yards. Use the trench spoils calculator for loose yards and truckloads.
Do I enter cover or invert depth?
Enter the excavated depth from existing ground to the trench bottom you will actually dig. Cover over the pipe is smaller than that depth by the pipe OD and bedding.
What about sloped trenches?
This page is a rectangle. For a 1:1 layback, split the trench into a rectangular core plus two triangular wedges, or use a typical section takeoff. Do not type the bottom width and hope the sides appear.
Disclaimer
These calculators are estimating tools for planning and field checks. They are not a substitute for approved plans, specifications, licensed professional engineering, or governing standards. Confirm densities, waste factors, and yields with your supplier and project documents.