Free tool · Metric
Trench excavation and backfill calculator
Excavation, bedding, pipe zone and backfill volumes for a utility trench, with imported tonnes, haul-off truckloads and a live cross-section. Share any take-off as a link.
- Bedding
- 18.0 m³
- Pipe zone
- 61.1 m³
- Backfill
- 216.0 m³
- Pipe displacement
- 4.9 m³
- Imported material
- 295.1 m³ ≈ 620 t
- Haul-off
- 375.0 m³ loose · 38 loads
Vertical walls deeper than 1.2 m need shoring, a trench box or sloping under the WorkSafeBC OHS Regulation.
How it works
- Cross-section area from bottom width, depth and side slope
- Bedding, pipe zone and backfill split by height above the trench bottom
- Pipe displacement taken out of the pipe zone
- Bank volumes times length; swell converts haul-off to loose volume
- Loads rounded up; imported tonnes from your density figure
Before you price it
- Preliminary quantitiesUse contract drawings and specifications for trench width, bedding and pipe zone dimensions, and add your compaction and waste factors.
- Trench safetySloping, benching and shoring follow the WorkSafeBC OHS Regulation and a qualified professional’s design where required.
- Need a full take-off?For measured quantities from IFC drawings, priced to MMCD pay items, see estimating.
Questions
Frequently asked.
How is the trench excavation volume calculated?
The trench is treated as a prism of constant depth. The cross-section is a rectangle for vertical walls, or a trapezoid when a side slope is entered, and its area is multiplied by the trench length. The result is the bank (in-place) volume.
How are bedding, pipe zone and backfill split?
Bedding runs the full trench width from the bottom up to the bedding thickness. The pipe zone runs from the top of the bedding to the chosen cover above the pipe crown, less the volume the pipe itself occupies. Backfill is everything from the top of the pipe zone to the surface.
What do the swell and truck numbers mean?
Excavated soil bulks up when dug. The swell percentage converts bank volume to loose volume, and the loose volume divided by the truck capacity gives the number of loads, rounded up. Swell varies with the soil, so use the figure from your geotechnical data or experience.
Does it include compaction or waste allowances?
No. Volumes are compacted, in-place quantities with no waste or compaction allowance, so add the factors your project uses before ordering material or pricing.
Can I use it for a BC project?
It works in metric units and suits utility trenches priced to MMCD or municipal specifications, but it gives preliminary quantities only. Trench geometry, bedding and pipe zone dimensions come from the contract drawings and specifications, and trench safety must follow the WorkSafeBC OHS Regulation.