Concrete trench-fill volume
Concrete Trench Fill Calculator
Estimate concrete to fill a rectangular trench from its net length, average width, and concrete fill depth, with an optional percentage for waste.
Trench-fill quantity
Enter the trench dimensions
Use the average excavated width and the actual depth to be filled with concrete. The calculation makes no deduction for pipe, conduit, gravel, or other displacement.
Enter dimensions and choose a waste allowance, then calculate.
Methodology 1.0.0 · Calculator 1.0.0
How the trench-fill calculation works
The calculator multiplies net trench length × average width × concrete fill depth as a rectangular prism, then applies the selected 0%, 5%, 10%, or 15% arithmetic waste allowance. The adjusted result is shown in cubic yards, cubic feet, and cubic meters.
Verified example
40 ft × 18 in × 12 in trench with 5% waste
2.33 yd³63.00 ft³
Independently derived case A starts at 60 cubic feet and applies 5%, producing 63 cubic feet, or about 2.33 cubic yards.
Measurement tips
- Measure the trench after excavation and use a representative average width rather than an idealized plan width when appropriate.
- Enter only the depth that will actually be filled with concrete, excluding gravel or other base layers.
- Count intersecting trench segments once; split materially different widths or depths into separate calculations.
- Subtract known displacement separately if the trench contains pipe, conduit, forms, or other material that concrete will not occupy.
Concrete Trench Fill Formula Reference
Reviewed relationship
For dimensions supplied by the user, the calculator treats the concrete-filled space as a rectangular prism:
raw volume = net trench length × average trench width × concrete fill depth
adjusted volume = raw volume × (1 + selected waste percentage)
The waste selection is optional in effect because 0% is available and is the default. It is arithmetic only and does not predict excavation irregularity, ground loss, overbreak, settlement, or supplier requirements.
Geometry, displacement, and overlap convention
The model assumes concrete fills the entire entered rectangular space. It makes no deduction for pipe, conduit, gravel, forms, sleeves, or other displacement. Count each intersecting trench segment once. Where width or fill depth changes materially, calculate uniform sections separately and add the results.
Unit reference
The calculator uses the international definitions 1 foot = 0.3048 meter and 1 inch = 0.0254 meter. The NIST Guide to the SI, Appendix B documents the length and volume conversion factors. Source reviewed 2026-10-05.
Scope and limitations
- The user supplies net trench length, average width, concrete fill depth, and a waste percentage.
- Concrete below or around an object is included unless the user subtracts that displacement separately.
- The calculator does not determine trench dimensions, concrete specification, reinforcement, bearing capacity, drainage, excavation safety, or code compliance.
- Verify actual excavation dimensions, exclusions, and ordering allowances before placement.