Field calculator
Trench excavation volume calculator (cubic yards)
Estimating a dig starts with the volume of soil to move. Length times width times depth in feet gives cubic feet, divided by 27 gives cubic yards, and divided by the truck capacity gives an approximate number of haul loads. Enter the three dimensions and a truck size. The number this gives is the bank volume, the soil in place before you dig it, which matters because excavated soil swells, commonly 15 to 30 percent depending on the soil, so the loose volume you actually load and haul is larger, and soil placed back as fill compacts to less than its bank volume. For real truck counts and backfill quantities, run the bank volume through a swell and shrink conversion. This is a simple prism estimate for a straight trench or a rectangular cut; sloped or benched excavation walls, required for stability, add volume beyond the neat line. Remember that an excavation 5 feet deep or more generally requires an OSHA protective system, which is a safety requirement, not an option.
Result
Trench or excavation volume: length × width × depth in feet gives cubic feet, divided by 27 for cubic yards (the bank, or in-place, volume), and divided by the truck capacity for an approximate load count. Enter the three dimensions and a truck size. The number this gives is the bank volume; excavated soil swells (commonly 15 to 30 percent), so the loose volume you actually haul is larger, and a fill compacts to less than bank, so convert with a swell/shrink calculation for hauling and backfill. This is a prism estimate for a straight trench or rectangular cut; sloped or benched walls add volume. Remember that an excavation 5 feet or deeper generally requires an OSHA protective system.
anvilfield.com/calculators/trench-excavation-volume-calculator · Free field calculators and FieldOS. A planning estimate, verify against the code, the manufacturer, and the engineer of record.
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Trench volume FAQ
When does a trench need protection?
A trench needs a protective system at 5 ft deep or deeper, unless it is cut entirely in stable rock, and shallower than 5 ft any time a competent person sees a hazard. People die in trenches under 5 ft, so treat the number as a floor. OSHA and the AHJ control the trigger.
What is a competent person on a trenching job?
A competent person can recognize the hazards in and around an excavation and has the authority to stop work and remove workers to fix them. On a trench they classify the soil, select the protective system, and inspect daily. Both the knowledge and the authority are required. Verify the role against OSHA Subpart P.
What are the three trench protection methods?
Slope it, shore it, or shield it. Sloping cuts the walls back at an angle set by the soil so they cannot slide. Shoring holds the walls up with a support system, often hydraulic. Shielding puts the worker in a trench box that survives a collapse. A job often combines two; the competent person and engineer govern.
How far should the spoil pile be from the trench?
Keep the spoil pile and any equipment at least 2 ft back from the trench edge, measured from the base of the pile, not the top. The weight near the lip is surcharge that pushes the wall in. On deep or wet trenches, keep it further back. The 2 ft minimum is OSHA's; verify the standard.
How much does the soil in a trench weigh?
A cubic yard of soil weighs around 3,000 pounds, about the weight of a small car, and saturated clay runs to the heavy end. That weight is why a cave-in pins a worker and crushes the chest in seconds. It is also why the spoil pile near the edge is a real load on the wall, not a minor one.