Excavation Swell Load Calculator

Explanation

Excavation volume estimation is more than length x width x depth. Soil expands when it is excavated because particles loosen and trap air. This expansion is called swell, and it is a major driver of hauling costs. Bank volume refers to the in-place volume of soil before excavation. Loose volume refers to the excavated material after it has expanded. Knowing both values is essential for material estimation and truck logistics in precision building projects.

The swell factor depends on soil type and moisture content. Granular soils such as gravel typically swell around 10 percent, sands around 12 percent, and clays can swell 20 to 30 percent or more because of higher cohesion and structure. This calculator applies a standard swell percentage to the bank volume to calculate the loose volume. Once the loose volume is known, the tool divides by truck capacity and rounds up to ensure you order enough loads. Rounding up is important because partial loads still incur mobilization costs and time on site.

This tool supports imperial and metric units, which allows you to work in feet and cubic yards or meters and cubic meters. It is a planning tool for excavation bids and scheduling, not a substitute for geotechnical investigation. Swell varies by soil classification and compaction state, so field verification is still required for critical earthwork or load-bearing foundations. Use this estimator as a realistic baseline for hauling, staging, and disposal planning.

Moisture content changes swell behavior. Wet clay can swell differently than dry clay, and sandy soils can settle quickly once disturbed. If you are excavating for backfill, you may need to apply a shrink factor to estimate compacted volume, which is separate from swell. In practice, contractors often track both loose and compacted volumes to avoid shortages or surplus trucking. Document assumptions for bids and compare against actual haul tickets.

Formula

Bank volume: Vb = L x W x D

Loose volume: Vl = Vb x (1 + swell)

Truck loads: loads = ceil(Vl / capacity)

Example Calculation

A 20 ft x 10 ft x 3 ft excavation has a bank volume of 600 cubic feet, or 22.22 cubic yards. With clay swell at 25 percent, the loose volume becomes 27.78 cubic yards. With a 10 cubic yard truck, you need 3 loads.

FAQs

What if I have multiple soil layers?

Use weighted averages or run separate calculations for each layer and sum the results.

How do I choose the swell factor?

Use geotechnical data when available, otherwise select a conservative preset for your soil type.

Can I enter truck capacity in tons?

This calculator uses volume. If you have tonnage, convert using soil density and moisture content.

Does this account for bulking or shrink for backfill?

No. Swell models excavation expansion. Compaction shrinkage should be estimated separately.

Why does the calculator round up loads?

Hauling logistics require full truck counts, so partial loads still count as a trip.

How it works

This tool applies a swell percentage to bank volume and divides by truck capacity to estimate loads. All calculations run client-side.

Disclaimer

Results are estimates. Soil conditions vary, and hauling requirements should be verified against site data and local regulations.