Excavation Volume & Truckload Calculator
The hole and the haul are two different numbers. Enter the excavation and the soil, and this calculator gives the bank volume in the ground, the loose volume once it is dug and on the truck, and how many loads that becomes at your body capacity. Swell factors are measured values from a state DOT study, shown with their full range — because on clay that range decides the truck count.
Results are estimates for planning purposes. Verify with your supplier, engineer, or a qualified professional before ordering material or performing work.
Swell factors by soil type
Bank-to-loose expansion is the number that turns a hole into a haul. These are measured values: a WisDOT research team sampled Wisconsin soils, ran Proctor and in-situ density tests, and measured the loose state with a unit box. Beside them is what the same agency's general guidance says — and the study's own conclusion is that the two do not always agree.
| Soil | USCS | Measured swell | WisDOT guideline |
|---|---|---|---|
| Sand with gravel | SW-SM, SM | 16–23% | — |
| Clean sand | SP | 4–8% | 10–15% |
| Silty sand | SM, SP-SM, SC-SM | 2–27% | 15–25% |
| Silt | ML | 27% | 20–30% |
| Clay | CL, CH | 26–58% | 25–35% |
Measured values from Table 4.10 of WHRP G22-05 (WisDOT, December 2023); guideline values from Table 1.1 of the same report. The study also found that only about 31% of the state DOTs it surveyed use specific expansion values for natural soils at all — most work from experience. That is why a swell number is so hard to find, and why the spread on silty sand and clay is wide enough to change your truck count.
Bank, loose, compacted: three yards, one ton
Every earthwork argument comes from someone quoting one state and someone else hearing another. The mass never moves; only the air between the particles does.
- Bank — in the ground, undisturbed. This is the hole on the plan, and normally the pay quantity for excavation.
- Loose — in the stockpile or the truck, after the bucket has broken it up. This is what you haul, what the landfill scale weighs, and what fills a body.
- Compacted — placed and rolled in lifts. Denser than bank for most soils, which is why a fill takes more borrow than its own volume. The same study measured that compacted-to-bank step at 9–10% for a clean sand and anywhere from −5% to 9% for clay: in eastern Wisconsin, some clays were already at or above their Proctor maximum in the ground.
The limit that bites first is pounds, not yards
A body is rated in cubic yards, but a highway is regulated in pounds. On the Interstate System and reasonable access to it, 23 CFR 658.17 caps a vehicle at 80,000 lb gross, 20,000 lb on any single axle and 34,000 lb on a tandem, with the Federal Bridge Gross Weight Formula governing consecutive axle groups. States set their own limits off the Interstate, and permits exist for nondivisible loads — dirt is not one.
Wet clay reaches those numbers with the body only part full. That is why this calculator will run the weight check for you the moment you give it a density and a payload limit, and why it will tell you which of the two governs instead of quietly picking one. What it will never do is invent a density for your soil: FHWA's own soils manual puts a clean sand between 85 and 138 lb/ft³ on packing alone.
Where the pile goes
The spoil you do not haul away is still on your site, and if it sits at the edge of an open excavation it is a load on the wall. 29 CFR 1926.651(j)(2) requires spoil, materials and equipment to be kept at least 2 ft back from the edge, or held by a retaining device, or both. If the loose yardage on this page is larger than the room you have, that is a plan to make now and not at 7 a.m. Size the excavation itself with the trench slope calculator.
How it's calculated
- Bank volume, the hole in the ground
rectangle: A = length × width · circle: A = π / 4 × diameter² · triangle: A = base × height / 2; V bank (ft³) = A × depth (ft) → yd³ = ft³ / 27- Loose volume, what comes out
V loose = V bank × (1 + swell % / 100)Measured bank-to-loose expansion by soil classification: sands with gravel 16–23%, clean sands 4–8%, silty sands 2–27%, silts 27%, clays 26–58%. The midpoint drives the result; the range is shown beside it.- Truckloads
loads = ceiling( V loose / truck body capacity )Always rounded up: half a load still sends a truck. If you also enter a density and a payload limit, the weight-limited count is calculated too, and the larger of the two governs.- Weight, only from your own density
tons = V bank (ft³) × in-place density (lb/ft³) / 2,000Weight is invariant: swell changes the volume, never the mass. No default density is offered for soil — none is publishable. FHWA's own soils manual puts a clean sand anywhere between 85 and 138 lb/ft³ on packing alone.- The limit that usually bites first
80,000 lb gross · 20,000 lb single axle · 34,000 lb tandem axle23 CFR 658.17, on the Interstate System and reasonable access to it. Wet clay fills the weight before it fills the body: the body capacity is the answer only until the scale says otherwise.
Frequently asked questions
Sources & references
- WHRP G22-05 — Weight-Volume Relationships and Conversion Factors for Soils and Aggregates of Wisconsin (WisDOT, December 2023): Table 4.10 measured bank-to-loose expansion factors by USCS class, Table 1.1 WisDOT's generalized guideline values
- 23 CFR 658.17 — Weight: 80,000 lb gross vehicle weight, 20,000 lb single axle, 34,000 lb tandem axle, plus the Federal Bridge Gross Weight Formula, on the Interstate System and reasonable access
- FHWA NHI-06-088 — Soils and Foundations Reference Manual, Volume I, Table 5-4: the dry unit weight of a clean fine-to-coarse sand runs from 85 to 138 lb/ft³ on packing alone — why no soil density is published here
- 29 CFR 1926.651(j)(2) — spoil, materials and equipment kept at least 2 ft back from the edge of an excavation, or retained by a device: what you do not haul away becomes a surcharge load on the wall
Content checked against these sources — last reviewed August 30, 2026.