Bank, Loose, and Compacted Cubic Yards: Soil Swell Explained

Why one excavation can have three cubic-yard quantities

Earthwork quantities change as soil moves. A volume measured in place before excavation is usually called bank cubic yards, or BCY. After the soil is dug, broken up, and loaded, it occupies more space as loose cubic yards, or LCY. After soil is placed and compacted into an embankment or fill, the result is commonly described as compacted cubic yards, or CCY.

These labels describe different states of the same material; they are not interchangeable units. A truck, a stockpile, an excavation plan, and a compacted fill section may all show different cubic-yard numbers for the same job. Naming the state beside every quantity prevents the most common earthwork estimating mistake: comparing a loose haul quantity with a bank excavation quantity as though they were the same.

The basic conversion formulas

For a simple rectangular excavation, calculate the in-place volume first: BCY = length × width × depth ÷ 27. The division by 27 converts cubic feet to cubic yards. For irregular areas, use the project’s survey or sectional quantities rather than forcing the site into one rectangle.

For a planning swell assumption expressed as a decimal, the loose quantity is: LCY = BCY × (1 + swell). If the loose quantity is known and you need to estimate the original bank quantity, use: BCY = LCY ÷ (1 + swell). A fill quantity needs its own project-specific relationship between the source material and the required compacted section; do not treat CCY as a universal fixed percentage of BCY.

• BCY: material in its natural or existing bank state.
• LCY: excavated material after disturbance, before final compaction.
• CCY: material placed and compacted to the project requirement.
• Swell: the increase in apparent volume after excavation or disturbance.
• Shrink: the reduction from a bank quantity to the compacted volume that the material produces in fill.

A transparent example

Suppose a rectangular cut is 120 feet long, 60 feet wide, and 8 feet deep. Its in-place volume is 120 × 60 × 8 ÷ 27, or about 2,133 BCY. If the estimator uses a 25% swell assumption for a preliminary haul plan, the loose quantity is 2,133 × 1.25, or about 2,667 LCY.

That 25% is an assumption for the scenario, not a measurement of the site. If a geotechnical report, test data, or local production history supports a different factor, replace the assumption and rerun the calculation. The same example can produce a different truck count, loading time, and disposal plan when the soil is wet, highly plastic, rocky, mixed, or handled with a different excavation method.

Why soil behavior cannot be reduced to one universal table

Swell and shrink depend on more than a soil label. FHWA guidance identifies factors such as material type, moisture, density, compaction method, construction or disposal method, and project controls. Clay mineralogy, water conditions, confinement, excavation disturbance, stockpiling, and blending can all change how much volume the material appears to occupy.

That is why this guide does not publish a single “ASTM soil type equals fixed swell” table. ASTM or USCS classification can help describe a material, but classification alone does not establish the exact quantity change for a specific excavation. Use the geotechnical report or measured local data when available, and label the calculator value as a planning assumption when it is not.

Hauling: volume is only half the question

Truck planning starts with the loose volume, but a truck may reach its legal or practical payload limit before its body is full. Density, moisture, material type, truck configuration, facility rules, and the route all matter. Use the calculator’s truckload output as a planning quantity, then confirm the actual payload, body capacity, scale procedure, and accepted material with the hauler and receiving facility.

Haul distance also affects production. Loading, queuing, traffic, dumping, return travel, and site access can matter as much as the one-way mileage. Keep the haul assumption visible in the estimate, and rerun the scenario if the material must be stockpiled, screened, blended, exported, or hauled to separate facilities.

Compaction and fill verification

Compacted cubic yards describe the finished fill condition, not simply the amount of dirt placed by a loader. The project specification may set a target density, moisture range, lift thickness, material type, and testing frequency. Proctor testing and field density testing help establish whether the placed material meets that project requirement; a generic percentage should not be presented as universal.

FHWA notes that compaction changes strength, stiffness, permeability, erosion resistance, and swelling potential. Wet or dry material, unsuitable soil, variable lifts, poor drainage, and inadequate equipment can produce a result that differs from the estimate. Confirm the fill specification, testing responsibility, undercut limits, imported material, and proof-roll or inspection requirements before relying on a CCY quantity for a bid or schedule.

How to use the earthwork calculator responsibly

Enter the geometry or known cut and fill quantities, then select the soil and equipment assumptions that best match the current information. The workstation reports bank, loose, and compacted quantities separately so the measurement state remains visible. Use the haul distance and machine choice to frame a production scenario, not to promise a guaranteed cycle time.

Run a second scenario whenever the factor is uncertain or the consequence is material. Compare the result using the geotechnical recommendation, a conservative planning assumption, and a measured production history when those inputs exist. Save the permalink with the assumptions, attach the source or report used, and give the same quantity definitions to the estimator, contractor, hauler, and owner.

• Confirm the survey basis and whether each quantity is BCY, LCY, or CCY.
• Replace assumed swell or shrink with project data when available.
• Check material moisture, contamination, rock, topsoil, and unsuitable-soil allowances.
• Confirm truck payload, body capacity, route, facility acceptance, and scale rules.
• Confirm the fill specification, lift thickness, moisture, density, and testing plan.
• Show the assumptions and uncertainty in the estimate instead of hiding them in one number.