How to use this calculator
- Enter Length in ft.
- Enter Width in in — or tap a preset badge to auto-fill a typical value.
- Enter Depth in ft.
- Press Calculate. The highlighted row is your order quantity; the note beneath it translates the number into real-world terms.
Formula & constants
Trench volume = length × (width ÷ 12) × depth ÷ 27 cu yd. An 18 in wide, 3 ft deep utility trench produces one cubic yard every 6 linear feet — plus 25% swell when hauled. Every default in the fields above is editable — when your supplier’s spec sheet lists a different density, coverage rate or price, enter that number instead. The waste and compaction allowances follow common trade practice; see our methodology page for the derivation of each formula and the standards it references.
Where this fits in the project
Earthwork precedes everything: dig volumes set the budget for hauling and determine imported fill or base gravel. Bank volume expands when dug (swell) and imported fill shrinks when compacted — use the truckload calculator on loose volume, not bank volume.
How this connects to your project
No quantity stands alone — each material in the chain depends on the ones around it. These are the planning steps that pair with the trench calculator:
- Excavation Calculator — Trenching is linear, narrow excavation.
- French Drain Calculator — French drains are installed in trenches.
- Fill Dirt Calculator — Trenches are backfilled after utility installation.
- Compaction Calculator — Trench backfill must be compacted in lifts.
- Swell Factor Calculator — Trench spoil swells when excavated.
- Gravel Calculator — Pipe bedding in trenches uses gravel.
- Sand Calculator — Sand is used for pipe bedding in trenches.
Frequently asked questions
How deep must utility trenches be?
Per code and utility: water below frost line, electric 18–24 in, gas 18–24 in — call 811 before digging.
Does trench spoil go back in?
Partially — bedding and shading around pipe use imported sand/gravel; native spoil backfills above, minus the displaced pipe volume.
Last verified: — prices reflect current national averages. See our methodology.
Estimates are for planning. Material densities, coverage rates and prices vary by region and supplier — confirm final quantities before ordering, and check local code where structural or electrical work is involved.