FREE FIELD CALCULATOR

Trench volume, pipe and backfill

Find how many yards you’ll excavate, how much bedding and backfill you need, and how many truckloads to plan for.

What you’ll need

Trench length, bottom width and depth
Side slopes or bench sizes, if the sides aren’t vertical
Pipe outside diameter and bedding height, for pipe work
Truck capacity, payload limit, swell and loose density, for hauling

Cross-section shape

Length (ft)Bottom width (ft)Depth (ft)

Left slope (horizontal : 1 vertical)Right slope (horizontal : 1 vertical)

Bench layers: height, total width (ft)

One layer per line, bottom first. Heights must total the depth. First width must equal bottom width; upper layers widen equally on both sides. This describes your section, not a safe excavation design.

Pipe, bedding and backfill

Equal pipes run the full length, evenly spaced within the bottom width. Enter outside diameter including the pipe wall. Bedding is the material placed under and around the pipe; it fills the trench width up to the height you enter.

Pipe count

Pipe outside diameter (ft)Clearance under pipe to trench bottom (ft)

Height to top of bedding, from trench bottom (ft)

Excavated material and trucks

The starting values are illustrative. Replace them with factors for your material and actual truck. Installed bedding/backfill volumes do not include ordering or compaction factors.

Material starting values

Swell factor (1.15 = 15% more loose material)Loose density (short tons / yd³)Truck capacity (loose yd³)Payload limit (short tons, optional)

Enter your inputs and calculate.

Try it with these numbers

Choose Vertical sides. Enter length 90, bottom width 4 and depth 3 feet.
Leave pipe count and bedding height at 0. Use swell 1.15, loose density 1.35 and truck capacity 12. Leave payload blank for this first check.
Choose Calculate. You should see 40 bank yd³, 46 loose yd³ and 4 loads, checked by volume only.
Enter a payload of 15 short tons and calculate again. The 62.1-ton haul needs 5 loads; weight now controls.
Try Sloped sides with 1 on each side. The top widens to 10 ft and excavation becomes 70 bank yd³. Use the section required for your job; this is an arithmetic example.

Reading your result

Bank yards are the space you dig before material loosens. Loose yards are the spoil you haul after the entered swell. Truckloads use the larger of the volume and weight checks when payload is entered.

Bedding and backfill are the spaces left to fill after subtracting the pipe. Ask your supplier how to convert those spaces into an order for the specified material and compaction. Pay quantities follow your contract’s measurement basis; this estimate does not set it.

A 2-ft outside-diameter pipe along the 90-ft vertical trench takes about 10.47 yd³ of space. Bedding and backfill together become 29.53 yd³, while excavation stays 40 yd³.

Where this goes wrong on site

Digging before the locate. Wisconsin requires notice to Diggers Hotline at least 3 working days before you dig, and a new notice if work doesn’t start within 10 days of the scheduled date or stops for more than 10 days. Minnesota requires at least 48 hours, not counting the day you call, weekends or holidays.
Pricing a vertical-sided trench past 5 feet. From 5 feet deep, OSHA requires a protective system unless the dig is entirely in stable rock. That means shoring, a trench box or sloped sides. Rerun the section with sloped sides to see how many more yards that moves.
Spoil right at the edge. OSHA requires excavated material to be kept at least 2 feet back from the edge, so plan room for the pile beside the trench.
Measuring top width and entering it as bottom width counts the slopes twice.
Entering nominal pipe size instead of outside diameter. A 24-inch pipe entry is 2 ft, not 24.
Using one depth for a run that changes noticeably. Split the run and calculate each section.

Sources: Wis. Stat. 182.0175 · Minn. Stat. 216D.04 · OSHA 29 CFR 1926.652(a) · OSHA 29 CFR 1926.651(j)

How the math works

Vertical section = bottom width × depth. Sloped section adds (left + right H:V) × depth² ÷ 2. For benches, add each layer’s width × height. Bank yd³ = section area × length ÷ 27. Loose yd³ = bank × swell. Weight = loose yards × loose density. Bedding and backfill subtract the pipe volume occupying each zone.

Keep the number with the job

Calculate above, then download a Letter or A4 PDF, copy the result or share it from your phone. The result sheet keeps your inputs and assumptions. Changing an input means you need to calculate again before exporting.

Open the private field workspace for saved jobs and reports across your phone and computer, or read the free-calculator guide. Tell Jesse what would make this easier on your job.

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