Free tool · Takeoff
Excavation and Trench Volume Calculator
Enter each trench or pit with its length, bottom width, depth and side slope, and the calculator gives the cubic yards to dig, the loose yards after the soil swells, and the truck loads to haul it. For a trench with pipe, add the pipe size and it shows the backfill left after the pipe takes its share.
The numbers stay in your browser: we do not store or receive them.
Trenches and pits
Side slope is the run for each 1 ft of depth: 0 is vertical sides, 1 is a 1:1 slope. A trench uses its bottom width.
Hauling
Dig (bank)
266.7 cu yd
7,200 cu ft in the ground
Loose, with 25.0% swell
333.3 cu yd
Truck loads
34
10.0 cu yd trucks
Backfill (bank)
230.3 cu yd
pipe takes up 36.36 cu yd
This is 5 ft deep or more. OSHA’s excavation rules (29 CFR 1926, Subpart P) generally require a protective system such as sloping, shoring or a trench box at that depth, and a competent person to inspect the excavation. This calculator figures volume only and does not design one.
| Line | Shape | Depth (ft) | Top (ft) | Cu ft | Cu yd |
|---|---|---|---|---|---|
| Line 1 | Trench | 6.0 | 9.0 wide | 7,200 | 266.67 |
How the volume is figured
Trench = length × depth × (bottom width + side slope × depth). The side slope is the horizontal run for each 1 ft of depth, so 0 is straight sides, 1 is a 1:1 slope, and the top is wider than the bottom by twice the slope times the depth.
Pit or basement with sloped sides uses the prismoidal formula: depth ÷ 6 × (bottom area + 4 × middle area + top area). It is exact for a rectangle with sloped sides, where the width grows with depth. With straight sides it is just length × width × depth.
Cubic feet are divided by 27 to get cubic yards. Soil measured in the ground is bank yards.
Swell, trucks and backfill
Dug soil takes up more room than it did in the ground. Swell is that increase as a percent, so loose yards = bank yards × (1 + swell). It depends on the soil: loose sand swells less than heavy clay. The box starts at 25 percent, so replace it with the figure for your soil. Truck loads = loose yards ÷ the truck size in loose yards, rounded up.
Backfill = the bank volume minus the space the pipe takes up (π ÷ 4 × the pipe diameter² × length). It is measured in the ground. It is not compacted yards, and it does not include bedding stone or sand.
A worked example
200 ft of 30 in storm pipe in a trench 3 ft wide at the bottom and 6 ft deep with sides sloped 1/2 to 1 has an average width of 3 + 0.5 × 6 = 6 ft, so the trench is 200 × 6 × 6 = 7,200 cu ft, or 266.7 cu yd in the ground. The top is 9 ft wide.
At 25 percent swell that is 333.3 loose cu yd, or 34 loads in 10 yd trucks. The pipe takes up 36.4 cu yd, leaving about 230.3 cu yd of backfill.
Trench safety
OSHA’s excavation rules (29 CFR 1926, Subpart P) generally require a protective system such as sloping, shoring or a trench box for trenches 5 ft deep or more, and a competent person to inspect the excavation. Deeper cuts may need an engineered design. This calculator only figures volume. It does not design a protective system or check that your slope is safe for the soil.
What this does not do
It does not add bedding or shading layers, compaction shrink, benching, sheeting and shoring, stripping of topsoil, or groundwater. Enter each trench or pit with the dimensions at the bottom and use a separate line where the cross section changes.
FAQ
How do I calculate the volume of a trench?
Multiply the length by the depth by the average width. With straight sides the width is the same top to bottom. With sloped sides the average width is the bottom width plus the slope times the depth. Divide by 27 for cubic yards.
What is the difference between bank and loose yards?
Bank yards are the soil measured in the ground. Loose yards are the same soil after it is dug, which takes up more room. Trucks haul loose yards.
What swell factor should I use?
It varies with the soil, so use the figure from your soils report or your experience. The box starts at 25 percent, a number often used for common earth, and you can change it.
What does 1:1 or 1/2:1 mean?
It is the side slope as horizontal to vertical. A 1:1 slope goes out 1 ft for every 1 ft down, and 1/2:1 goes out half a foot for every foot down. Enter the horizontal part as the side slope.
Does the calculator include shoring?
No. It figures the volume of soil only. Trenches 5 ft deep or more generally need a protective system under OSHA rules, so plan and price that separately.
Is anything I type saved?
No. The calculation runs in your browser and nothing is stored or sent to us.
Pricing the whole site job? PoPs Estimating measures trenches, pits and haul from your plans and keeps the quantities tied to the bid.
Questions?
Ask us anything about PoPs Suite, pricing, or running a construction company. A real person answers, usually within a business day.