Trench Volume Calculator
Enter your trench length, width, and depth to find the volume and weight of soil you’ll need to haul away, backfill, or truck in.
Measure straight across the widest point.
Adjust depth below if needed.
Covers spillage and compaction. 5–10% is normal.
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Bags or bulk delivery?
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Coverage & weight
Material profile
For the default 30 ft long, 1.5 ft wide trench dug 24 inches deep, you’ll excavate about 3.33 cubic yards of soil, weighing roughly 3.5 tons at average soil density. That’s the volume you need to plan haul-off, spoil storage, or backfill material for.
Trench spoil volume for common dig sizes
These estimates use average soil at 2,100 lb per cubic yard with no waste allowance, since spoil volume is what actually comes out of the ground.
| Trench | Depth | Cubic yards | Tons |
|---|---|---|---|
| Water line, 50 ft x 1 ft | 24 in | 3.70 yd³ | 3.89 tons |
| Sewer lateral, 80 ft x 2 ft | 36 in | 17.78 yd³ | 18.67 tons |
| Electrical conduit, 40 ft x 1 ft | 18 in | 2.22 yd³ | 2.33 tons |
| Footing trench, 60 ft x 1.5 ft | 18 in | 5.00 yd³ | 5.25 tons |
| Drain line, 100 ft x 1 ft | 12 in | 3.70 yd³ | 3.89 tons |
| Short repair, 10 ft x 1.5 ft | 24 in | 1.11 yd³ | 1.17 tons |
Soil types, density and drainage for spoil estimates
| Type | Weight per yd³ | Best for | Drainage |
|---|---|---|---|
| Average soil | 2,100 lb | Weight estimate for haul-off | Variable |
| Clay soil | 2,300 lb | Weight estimate for haul-off | Poor |
| Sandy soil | 2,600 lb | Weight estimate for haul-off | Excellent |
Figures are for dry material. Wet or freshly delivered material can weigh noticeably more.
How to calculate trench spoil you need
- Measure the trench length and width run a tape along the centerline for length, and across the open cut for width.
- Set the dig depth 12in for shallow drain lines, 18-24in for utility and footing trenches, deeper for frost-line or main lines.
- Convert to cubic yards multiply length × width × depth in feet, then divide the cubic-foot volume by 27.
- Pick a reference soil density average soil, clay, or sandy soil, to estimate the weight of spoil for haul-off trucking.
- Convert to tons multiply cubic yards by the density (2,100-2,600 lb/yd³) and divide by 2,000.
Worked example
Using the calculator’s default 30 ft × 1.5 ft trench dug 24 inches deep in average soil:
- Area30 ft × 1.5 ft = 45 sq ft
- Depth in feet24 in ÷ 12 = 2 ft
- Volume45 sq ft × 2 ft = 90 cu ft
- Waste allowance0% — spoil volume is measured as-dug, not padded
- Cubic yards90 ÷ 27 = 3.33 yd³
- Weight (average soil, 2,100 lb/yd³)3.33 × 2,100 = 7,000 lb = 3.5 tons
- Order / haul-off amount3.5 tons — round to the nearest quarter ton for trucking
- Bagged option180 bags (0.5 cu ft each) if hand-hauling spoil in small loads
Recommended depth by project
| Project | Recommended depth | Notes |
|---|---|---|
| Trench purpose | Typical depth | Notes |
| Sprinkler / low-voltage line | 6-8 in | Shallow, but check local code minimums |
| Drain line trench | 12 in | Enough fall and cover for gravity drainage |
| Footing trench | 18 in | Depth often set by local frost-line or code requirement |
| Utility line trench (water, gas) | 24 in | Standard cover depth for most residential utility lines |
| Sewer lateral / main line | 30-48 in | Deeper to maintain slope from house to street connection |
| Frost-line water service | 36-60 in | Varies by climate — check your local frost depth |
Bags or bulk delivery?
Trench spoil is usually reused as backfill or hauled off, not purchased, so bagged material only matters if you need to bring in clean fill or bedding sand for pipe. Bagged fill costs far more per ton than a bulk delivery, so it only pencils out for small repair digs.
- Small repairsunder 0.5 ton (about 20 bags) — bags make sense for a short utility repair or a single post hole.
- Medium jobs0.5 to 3 tons — compare bag totals against a bulk minimum delivery plus fee.
- Large jobsover 3 tons — bulk delivery or an on-site spoil pile is cheaper and avoids hauling dozens of bags.
Common mistakes
- Forgetting trench walls aren't verticalsloped or benched trenches (required by OSHA past 5 ft deep) hold more soil at the top than a straight rectangular calculation assumes.
- Not accounting for soil swellexcavated soil expands 15-30% once dug and loosened, so the spoil pile will look bigger than the cubic yardage that came out of the hole.
- Underestimating spoil storage spacea 3.5-ton trench dig produces a spoil pile roughly 5-6 ft across — plan where it goes before you start digging.
- Ignoring utility locatesalways call 811 before digging any trench, regardless of depth, to avoid hitting buried gas, electric, or communication lines.
- Mixing topsoil and subsoil spoilkeep the topsoil layer separate if you plan to restore the surface — mixing it with subsoil ruins it for reuse.
- Skipping bedding materialpipes and conduit need a clean bedding layer (sand or fine gravel) under and around them, not just native soil backfill.
What this calculator assumes
Adjust your result if your project differs from these.
- Depth is the as-dug trench depth from finished grade to trench bottom.
- Volume assumes straight, vertical trench walls; sloped or benched trenches hold more material.
- Density figures are for undisturbed soil; loosened spoil swells and takes up more space than the calculated cubic yardage.
- No waste percentage is applied by default since spoil volume is what actually comes out of the ground.
- Prices are material-only reference costs for bringing in backfill; excavation labor and equipment are separate.
- Always confirm depth against local utility burial code and call 811 before digging.
Common questions
How do I calculate trench volume?
Multiply trench length × width × depth (all in feet) to get cubic feet, then divide by 27 for cubic yards. A 30 ft × 1.5 ft × 2 ft trench is 3.33 cubic yards.
How much does a cubic yard of trench spoil weigh?
About 2,100 lb for average soil, up to 2,300 lb for dense clay or 2,600 lb for sandy soil, depending on moisture and composition.
Does excavated soil take up more space than the trench?
Yes — loosened spoil swells 15-30% compared to its undisturbed volume, so the pile will look larger than the trench volume calculated here.
How deep should a utility trench be?
Most residential water and gas lines are buried at least 24 inches; check local code, since frost-line requirements push this deeper in cold climates.
Can I reuse trench spoil as backfill?
Usually yes for native soil trenches, as long as it’s free of large rocks and debris; compact it in lifts to avoid future settling over the trench line.
How many tons of soil come from a 100 ft drain line trench?
At 1 ft wide and 12 in deep, about 3.7 cubic yards or 3.89 tons — see the reference table above for other sizes.
Do I need to call before digging a trench?
Yes, always call 811 (in the US) a few days before digging any trench to have utility lines marked, regardless of depth.
Should trench walls be sloped?
For trenches over about 5 ft deep, OSHA requires sloping, benching, or shoring to prevent collapse — this also increases the actual soil volume disturbed.
What's the difference between bank and loose volume?
Bank volume is the soil as it sits undisturbed in the trench; loose volume is that same soil after digging, once it has swelled and lost compaction.
How much backfill do I need after laying pipe?
Roughly the trench volume minus the pipe’s own volume — for most small pipes this is a small deduction, so trench volume is a close estimate.
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Project
| Shape | — |
| Dimensions | — |
| Depth | — |
| Area | — |
| Material | — |
| Waste allowance | — |
Volume & weight (incl. waste)
| Cubic yards | — |
| Cubic feet | — |
| Weight | — |
| Tons (rounded up) | — |
Shopping list
| Bulk order | — |
| Bagged alternative (0.5 cu ft) | — |
| Estimated cost | — |
Notes
Estimate generated by materialcalculate.com. Assumes uniform depth and standard dry material densities. Confirm quantities with your supplier before ordering.