Trench Calculator

Estimate excavation volume, soil swell and truck loads for a rectangular trench

Your result will appear here.

About the Trench Calculator

Trench quantity calculations help estimate excavation volume for utilities, drainage, footings and landscaping. Length, width and average depth determine the basic volume, while side slopes, bedding and backfill can make the field quantity different from a simple rectangular cut.

The calculator is useful for planning spoil removal and material replacement, but safe excavation also depends on soil conditions, trench depth, groundwater and applicable shoring or sloping requirements.

How to Use the Trench Calculator

  1. Enter trench length.
  2. Enter average trench width and depth.
  3. Choose the desired output unit such as cubic yards or cubic metres.
  4. If the trench has sloped sides or changing depth, divide it into sections or use an average geometry that reflects the actual excavation.

How the Calculation Works

For a rectangular trench, volume = length × width × depth after units are converted to a common system.

If multiple trench sections have different dimensions, calculate each volume separately and add them. Converting cubic feet to cubic yards requires division by 27.

Worked example

Trench Calculator Worked Example

100 ft trench, 2 ft wide and 3 ft deep

Volume = 100×2×3 = 600 ft³. In cubic yards, 600÷27 ≈ 22.22 yd³ before swell, side slopes or over-excavation.

Result guide

Understanding Your Trench Calculator Result

The geometric excavation volume is not the same as trucked spoil volume. Excavated soil often expands after removal, while some material may be reused as compacted backfill.

Before you rely on the answer

Assumptions and Limitations

  • Dimensions represent the intended excavation geometry.
  • The simple mode assumes constant rectangular width and depth.
  • Soil swell, groundwater, shoring and safe-slope requirements are separate from net geometric volume.

Practical tip

Using This Result in Practice

For disposal planning, distinguish bank volume from loose hauled volume. Ask the contractor or geotechnical source for an appropriate swell factor instead of using one generic percentage for every soil.

Related calculations

Useful Calculations to Continue With

For broader pits or earthwork shapes beyond a narrow trench, use the Excavation Calculator.

If the trench contains a pipe and you need internal fluid capacity, calculate that separately with the Pipe Volume Calculator.

Common questions

Trench Calculator FAQ

How do I calculate trench volume?

Multiply trench length, width and depth after converting all dimensions to compatible units.

Why is hauled soil volume larger than trench volume?

Excavated soil often loosens and expands, creating a larger loose volume than the in-place bank volume.

Does the calculation include sloped trench sides?

Only if the selected geometry or entered average width accounts for them.