Fill Dirt Cubic Yard Calculator

How to calculate fill dirt cubic yards

Measure the space to be filled, including length, width and target depth. For a rectangular level area, use length (ft) × width (ft) × fill depth (in) ÷ 324. A 20 × 15-foot area raised 6 inches has a geometric volume of 20 × 15 × 6 ÷ 324 = 5.56 yd³. This describes the target space, not necessarily the loose truck quantity.

Where soil is being moved between cut and fill areas, measure existing and proposed grades. Cut volume is the material removed, and fill volume is the volume required to establish the new grade. Subtracting one number from the other without accounting for soil state, suitability and loss can produce an inaccurate trucking plan.

Bank, loose and compacted cubic yards explained

These are three different measurement states. Bank cubic yards (BCY) describe earth in its original undisturbed position. Loose cubic yards (LCY) describe excavated or stockpiled material after its structure is disturbed. Compacted cubic yards (CCY) describe fill placed and compacted to the specified condition.

A volume of material may swell when dug, then reduce in volume when placed and compacted. The Federal Highway Administration's earthwork design guidance ↗ explains how shrink and swell depend on material and field conditions. A cubic yard measured in place cannot simply be assumed to equal one cubic yard in a truck.

Use density measurements or project-specific swell and shrinkage factors when converting between states. The calculator's extra percentage field is for scenarios, not a substitute for geotechnical testing or an earthwork mass-balance plan.

Fill depth chart for a level 100-square-foot area

For preliminary yard leveling, depth has a direct effect on required volume. The following values represent a uniform finished fill layer, without correction for settlement, compaction or changes in base elevations. A shallow top-up and a one-foot raise are very different hauling jobs.

Estimating fill for a sloped yard or changing grade

A flat-area formula assumes uniform fill depth. When the finished grade tapers from one end to another, depth varies across the footprint. For a simple planar taper with constant width and a depth that changes linearly, the average of the two end depths can estimate the geometric volume. This shortcut is not appropriate for irregular terrain, hollows or changing side slopes.

Example: a rectangular 40 × 20-foot zone rises from zero fill at one end to 12 inches at the other, with a linear grade across its 40-foot length. The average fill depth is (0 + 12) ÷ 2 = 6 inches. Estimated volume = 800 × 6 ÷ 324 = 14.81 cubic yards in the finished geometric space. This ignores material-state changes and any drainage or settlement requirements.

For meaningful siteworks, measured spot elevations, contour surfaces or engineering cross-sections provide better estimates than a guessed average depth. Keep erosion, drainage direction and adjoining properties in mind before altering grade.

Trench backfill: subtract the space occupied by other materials

A trench's gross excavated volume is not necessarily the volume of fill dirt to order. Pipes, conduits, concrete structures, drainage stone or bedding occupy part of the trench. The net backfill volume is the measured void to be refilled after accounting for the installed material and layers.

For example, a straight trench 60 feet long, 2 feet wide and 3 feet deep has a gross box volume of 60 × 2 × 3 ÷ 27 = 13.33 cubic yards. If a specified bedding layer occupies part of that space, estimate its volume separately and subtract it from the gross void before calculating soil backfill. This example is only a quantity calculation and does not establish safe trench dimensions, support systems or excavation procedures.

Swell, shrinkage and compaction factors

Swell occurs when a mass of excavated soil occupies more bulk volume after disturbance. Shrinkage describes a reduction in volume associated with placement, compaction or earthwork balance. Moisture, gradation, organic content and existing density influence these effects. No single factor applies to every sandy, clayey or rocky soil.

For a strictly illustrative calculation, if project data say 1 compacted cubic yard requires 1.15 loose cubic yards, a 10-CCY finished fill would require 11.5 LCY. This 1.15 ratio is an example supplied for arithmetic; it is not a default material factor and must not be applied without project-specific information.

Compaction specifications may reference tests, moisture-density relationships or a target dry density. For load-bearing fill, the appropriate material, lift thickness, compaction method and verification belong to the project's engineering requirements.

Choosing fill material: clean fill versus topsoil

Fill dirt is primarily used to build or restore grade, backfill voids or form a suitable subgrade. Topsoil is selected for its value as a growing medium. A soil product suited to planting is not automatically appropriate for structural compaction, and material selected as structural fill may be poor as a surface planting layer.

Ask the supplier about particle size, organic material, debris, contamination concerns and suitability for your project. Imported fill may require testing or approval under project documents or local rules. If the goal is a healthy lawn or garden surface, calculate that separate upper layer using the topsoil cubic yard calculator.

Dump truck quantities, costs and delivery planning

Earthwork deliveries are often constrained by both hauling capacity and legal payload weight. A bed that has room for several loose cubic yards may reach its weight limit first. Ask the contractor or supplier how loads are measured and whether invoices use loose cubic yards, bank yards, short tons or truck trips.

For preliminary budgeting, calculate the intended order quantity in the supplier's billing unit and multiply by its quote. Include hauling, disposal of unsuitable excavated material, access, spreading, compaction and testing where applicable. A geometry-only calculator cannot determine disposal classifications, material suitability or total project cost.

When to use a professional earthwork estimate

A simple fill quantity is most useful for small, level, nonstructural areas with known dimensions. Retaining walls, building pads, significant slope changes, utility excavation, flood-prone property and roadway embankments can require survey measurements, drainage design, geotechnical evaluation, permits and inspected compaction.

Before purchasing fill, confirm existing and target elevations, whether the quantity is bank, loose or compacted, which material is specified, the depth and shape of each section, required testing and safe delivery access. For a basic flat-area calculation, the homepage cubic yard calculator provides the underlying geometric volume formula.