Trench Volume Calculator

Example data table

Example values are illustrative; field conditions may differ.

Formula used

Conversions: 1 ft = 0.3048 m, 1 yd³ = 0.7645549 m³.

How to use this calculator

1. Select a profile method that matches your trench shape.
2. Choose meters or feet, then enter length, depth, and bottom width.
3. Add side slope ratio or top width if your trench widens upward.
4. Set overbreak, swell, and shrink to match site conditions.
5. Enter truck capacity to estimate haul trips and logistics.
6. Optional: add density and costs for mass and budget estimates.
7. Press Calculate to see results above the form.
8. Use the download buttons to export your report.

Project notes and industry context

1) Why trench volume matters

Trench excavation quantity influences equipment selection, crew productivity, haul planning, and environmental controls. A reliable volume estimate reduces material shortfalls, avoids excess spoil stockpiles, and improves schedule confidence. This calculator reports in-place, excavated, loose, and compacted volumes for clear decision making.

2) Typical trench profiles used on sites

Many utility trenches are rectangular when shoring or trench boxes maintain vertical sides. Sloped profiles appear when soil conditions require battered walls. Trapezoidal sections are common for drainage lines and wider installations where top width increases for access.

3) Dimensions and tolerances to measure

Measure length along the centerline, then confirm depth to design invert. Record bottom width at the intended bedding level. For sloped excavations, document side slope ratio (H:V) from field method statements and confirm actual top width during trial digs.

4) Overbreak as a realistic adjustment

Overbreak covers irregular edges, loose pockets, and equipment tracking outside nominal lines. Small trenches might use 2–5% overbreak, while rocky ground or heavy buckets may need higher allowances. Apply it to excavation volume so downstream haul and disposal calculations remain consistent.

5) Swell and shrink for earthmoving logistics

Excavated soil expands when loosened, increasing haul volume. Swell often ranges from 10–35% depending on soil type and moisture. Shrink reflects compaction during backfill and can be 5–15% or more. Separating these factors improves truckload and backfill forecasts.

6) Truckloads and production planning

Truckloads are estimated from loose volume divided by truck capacity. Use consistent capacity units and consider operational factors such as heaped loads, route restrictions, and cycle times. For long trenching runs, even small percentage changes in swell or overbreak can shift haul trips significantly.

7) Mass and disposal considerations

When density is provided, the calculator estimates spoil mass. This supports haul weight checks and disposal documentation. Typical bulk densities may be around 1400–2000 kg/m³, but verify site-specific values. If disposal is charged by weight, convert tonnes using validated density measurements.

8) Cost inputs and reporting

Optional unit costs summarize excavation and disposal cost based on excavated in-place volume. Use rates aligned with your contracts, and consider whether costs should be tied to in-place, loose, or trucked volumes. Exported CSV and PDF reports help maintain traceable quantity records for site meetings and progress claims.

FAQs

1) Which profile should I choose?

Use rectangular for supported vertical walls, side slopes for battered excavations, and top-and-bottom widths when you know both dimensions from drawings or field checks.

2) What does overbreak represent?

Overbreak is extra excavation beyond nominal lines due to irregular ground, bucket overcut, or collapse. It increases excavated, loose, and truckload estimates without changing entered dimensions.

3) How do I pick a swell factor?

Swell depends on soil type and moisture. Use past job data where possible. If unknown, start around 20% for mixed soils, then refine using measured truck volumes and stockpile surveys.

4) What is the difference between loose and compacted volume?

Loose volume is the expanded spoil after excavation, mainly for hauling. Compacted volume is what the same material occupies after compaction, useful for estimating backfill quantities and void space.

5) Can this be used for trench bedding materials?

Yes. Use the in-place trench geometry as a base, then model bedding as a separate layer by using its thickness as depth and the relevant widths. Add layers to build total imported material volume.

6) Why is truckloads an approximation?

Truckloads assume full utilization of stated capacity and uniform material. Real projects vary due to heaping, moisture, travel time, and legal weight limits. Treat the value as a planning baseline.

7) What if my trench width varies along its length?

Split the trench into segments with consistent dimensions, calculate each segment, then sum the volumes. This is more accurate than averaging widths over long runs with changing geometry.