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Excavation Volume and Truck Load Calculator

How much spoil is coming out of the hole, and how many truck loads will it take to haul it away. Enter the dig dimensions, pick a soil type with the right swell factor, and see bank volume, loose volume, and truckloads in real time. Built for excavation contractors, not landscapers or DIYers buying mulch.

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The math, shown transparently

No black box. Here is exactly what the calculator computes on every input change. If any of these numbers look wrong, cross-check with a calculator of your own.

// Bank volume. In-place, undisturbed.

bank_ft³ = length × width × depth (imperial)

bank_yd³ = bank_ft³ / 27

bank_m³ = length × width × depth (metric)

bank_yd³ = bank_m³ / 0.9144³ (NIST yd to m)

// Loose volume. After the dirt comes out and bulks up.

loose_yd³ = bank_yd³ × swell_factor

// Truck loads. Always rounds up. A partial load is still a trip.

loads = ceil(loose_yd³ / truck_capacity_yd³)

Worked example

A 10 ft × 10 ft × 10 ft hole in common earth, hauled with a standard 12 yd³ tandem dump:

bank_ft³ = 10 × 10 × 10 = 1000 ft³

bank_yd³ = 1000 / 27 = 37.04 yd³

loose_yd³ = 37.04 × 1.25 = 46.30 yd³

loads = ceil(46.30 / 12) = ceil(3.858) = 4 loads

You can verify this and every other example in the test suite with any cubic yard calculator. The math is pure, no server calls, and the numbers are locked in a unit test so they cannot drift.

How swell factors work

When you excavate dirt, rock, or sand, it occupies more space loose than it did in the ground because it picks up air gaps. A swell factor (sometimes called a bulking factor) is the multiplier between in-place bank volume and loose excavated volume.

  • Common earth: about 25% swell. One cubic yard in the ground becomes 1.25 yd³ in the truck.
  • Dry sand: about 12%. Sand barely bulks because it is already loose packed.
  • Wet sand: about 5%. Water fills the voids, so less swell.
  • Clay (dry): about 35%. Clay holds its shape but air pockets add up fast.
  • Clay (wet): about 40%. Wet clay is heavy too. Watch for weight-limited loads.
  • Rock, blasted: about 65%. Shot rock is the fluffiest material you haul.
  • Topsoil: about 43%. Organic content makes topsoil bulk up more than you would expect.

These factors come from the Caterpillar Performance Handbook and the Spike VM reference tables. Those are the two sources that industry earthmoving calculations generally rely on. Real-world values vary with moisture, rock fragmentation, and how the loader works the material. Treat these as good planning numbers, not surveyed measurements.

How to use the calculator

  1. Pick your units. Imperial (feet and cubic yards) or metric (meters and cubic meters). Your choice is saved for next time.
  2. Enter the dig dimensions. Length, width, and depth. For irregular shapes, break the hole into rectangles and add them up.
  3. Select a soil type. Pick the closest match. If the site has a mix of materials, run the calculator once per soil and add the loads.
  4. Pick your truck. Choose from standard dump truck capacities or enter a custom value in cubic yards.
  5. Read the numbers. Bank volume, loose volume, and truckloads update in real time. Loose volume is what actually hits the truck bed.

Frequently asked questions

What is the difference between bank volume and loose volume?

Bank volume is the in-place, undisturbed dirt. It is what you measure from the surveyor's drawings before you dig. Loose volume is what you actually haul away after the dirt has been excavated and bulked up with air. Loose is always bigger than bank. The multiplier between them is the swell factor, and it depends on the soil type. Dry sand bulks up about 12%. Wet clay bulks up about 40%.

Why does my cubic yard calculator say I need more loads than yours?

Most generic cubic yard calculators ignore swell. They assume 1 yd³ of dirt equals 1 yd³ of truck space. That is wrong. When you dig 100 yd³ of common earth out of the ground, you get about 125 yd³ of loose material to haul. That is what the truck actually carries. Using bank volume to compute loads underestimates the real number by 20 to 40%. Enough to sink a bid.

Where do your swell factors come from?

Every swell factor in the soil dropdown is cross-checked against the Caterpillar Performance Handbook material tables and Spike VM's published bulking/swell reference. Where a range exists, we use the mid-range value, not the most aggressive one. Estimates bias toward being conservative, which is what you want on a bid.

Why does a partial load count as a full truckload?

Because you can't send half a truck. A 12 yd³ truck carrying 0.5 yd³ of spoil is still one trip to the dump. Same fuel, same driver time, same tipping fee. The calculator always rounds up, matching how real trucking billing works.

Does the calculator account for truck weight limits?

No. Truck capacities shown are volumetric (cubic yards). Dense materials like wet clay or wet rock may hit DOT axle weight limits before the bed is full, so the real-world load can be 10 to 20% smaller than the volumetric max. We flag this in the results. For rough planning it rarely matters. For hauling rates on heavy fill, check the truck's weight rating.

Is this free forever?

Yes. No signup, no email, no watermark. SpoilStack is a paid job tracker for excavation contractors. This tool is free.

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