Trench Volume Calculator

Work out trench volume instantly with clear inputs, formula shown and shareable results.

About Trench Volume Calculator

Trench excavation is a simple prism of length, width and depth. Within it, the bedding layer beneath the pipe is a separate imported material, and the remainder is backfill. Spoil is shown at 25 percent bulking because that is the volume actually needing space alongside the trench or on a lorry.

Formulas

Excavation

V = length x width x depth

Split

Bedding = length x width x bedding thickness; backfill = excavation - bedding

Worked example

With the default values below, Trench Volume Calculator returns Excavation volume of 72.00. Change any input above and every figure here is recalculated in your browser.

Inputs used

Trench lengthminimum 0.1 m: 100 m
Trench widthminimum 0.05 m: 0.6 m
Trench depthminimum 0.05 m: 1.2 m
Bedding thicknessminimum 0 mm: 150 mm

Results

Excavation volume: 72.00 m³
Bedding material: 9.00 m³
Backfill volume: 63.00 m³
Loose spoil to handle: 90.00 m³

Step by step

1Values used
2Excavation
3Split
4Excavation volume= 72.00 m³
5Bedding material= 9.00 m³
6Backfill volume= 63.00 m³
7Loose spoil to handle= 90.00 m³

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is the Trench Volume figure worked out?

V = length x width x depth. Trench excavation is a simple prism of length, width and depth.

Should the pipe volume be deducted from backfill?

For a large diameter pipe, yes. For small services the pipe displaces so little that ignoring it is well inside the accuracy of the trench dimensions.

What values do I need to enter?

This calculator takes 4 inputs: Trench length, Trench width, Trench depth, Bedding thickness. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.