Net fill volume in cubic yards = area (sq ft) × added depth (in) / 324. A 20 × 10-foot space at a selected 6-inch finished depth is 100 cu ft, or 3.703704 cu yd. That is the space to fill, not automatically the loose quantity to buy. Convert between compacted, loose and undisturbed volumes only with a factor that states its basis.
Measure the space, then identify the volume basis
- Measure the intended fill space after accounting for any material removal and the finished grade. Do not measure from grass blades.
- For a rectangle, area = length × width. Use the actual additional depth, not the height of the entire existing ground profile.
- Split different depths into non-overlapping sections, calculate each volume and add unrounded results.
- For an irregular yard or significant grade change, measurements must capture the elevations and slopes. A single shallow/deep average is not enough for a bumpy surface.
This is quantity planning, not a grading, drainage or foundation design. Structural support, retaining walls, slopes and changes near buildings need site-specific requirements and suitable material. A number of yards does not establish safe bearing capacity, drainage or compaction.
Three different meanings of a yard of dirt
| Volume state | Meaning |
|---|---|
| Undisturbed or bank | Material in its original ground position |
| Loose | Excavated material in a truck or stockpile |
| Compacted or installed | Material placed at the specified finished condition |
FHWA explains that material changes volume between excavation, transport and compacted fill, and that specifications must state the place and method of measurement. Its earthwork guidance calls for material characteristics and project-specific geotechnical information.1 A percentage based on undisturbed excavation cannot automatically be used as the percentage reduction from a delivered loose yard.
Formula and net-volume chart
Cu ft = net area × added depth (in) / 12.
Cu yd = net area × added depth (in) / 324.
One cubic yard equals 27 cubic feet. Keep full precision for later conversions and order rounding.
| Selected depth | 100 sq ft (cu yd) | 500 sq ft (cu yd) | 1,000 sq ft (cu yd) |
|---|---|---|---|
| 2 in | 0.617 | 3.086 | 6.173 |
| 4 in | 1.235 | 6.173 | 12.346 |
| 6 in | 1.852 | 9.259 | 18.519 |
| 8 in | 2.469 | 12.346 | 24.691 |
| 12 in | 3.704 | 18.519 | 37.037 |
| 18 in | 5.556 | 27.778 | 55.556 |
These are net geometric volumes at the selected depth, displayed to three decimal places. No loose-to-compacted conversion, reserve, density or sales increment is included. Depths are examples for calculation, not approved grading designs.
Compaction percentages: ask what the number means
Two superficially similar percentages give different answers:
“Order 15% more than the finished volume” means loose order = finished volume × 1.15.
“Loose volume reduces by 15% when compacted” means finished volume = loose volume × 0.85, so loose order = finished volume / 0.85.
These are mathematical definitions, not recommended factors for your soil.
For a selected 10 finished cu yd, those statements produce 11.5 and 11.764706 loose cu yd, respectively. Ask for a directly usable loose-yards-per-finished-yard relationship or a defined reduction with matching material and compaction conditions. Do not choose a middle percentage from unrelated websites. FHWA notes that original density and compactive effort affect the change.1
A separately chosen handling reserve and a supplier sales increment are different again. Do not stack them silently on a conversion that already includes losses. FHWA also distinguishes shrinkage from settlement of the entire embankment over weak ground; adding an arbitrary extra percentage does not solve that foundation problem.1
Three checked examples
1. A 20 × 10-foot rectangular space
At a selected 6-inch finished depth: 20 × 10 × 6 / 12 = 100 cu ft = 3.703704 finished cu yd. Suppose the project has a hypothetical verified relationship of 1.15 loose yards per finished yard. Loose target = (100 / 27) × 1.15 = 4.259259 cu yd. If this supplier actually sells quarter-yard increments, round up to 4.5 loose cu yd. No separate reserve is included. The factor and increment are example inputs, not universal rules.
2. A 24 × 16-foot space with a defined reduction
At a selected uniform 8-inch finished depth, net volume = 24 × 16 × 8 / 12 = 256 cu ft = 9.481481 finished cu yd. Suppose the supplied material is hypothetically verified to retain 80% of its loose volume at the specified installed condition. Loose target = (256 / 27) / 0.80 = 11.851852 cu yd. If the supplier sells half-yard increments, that becomes 12 loose cu yd. Simply adding 20% would give only 11.377778 loose cu yd, which is not the same relationship.
3. A straight, even depth taper
A 30 × 20-foot horizontal footprint needs a fill layer tapering linearly from 2 to 10 inches across the rectangle. Average depth = (2 + 10) / 2 = 6 inches. Net volume = 30 × 20 × 6 / 12 = 300 cu ft = 11.111111 cu yd. This shortcut assumes a linear taper over the full constant-width rectangle. For uneven ground, non-linear depth or changing width, use surveyed sections or appropriately weighted smaller areas instead. No conversion factor is assumed.
Convert a confirmed loose order into weight and loads
US short tons = loose yards × matching lb per loose yard / 2,000. Weight cannot be determined from cubic yards alone. Use the supplier’s density on the same volume and moisture basis as the order; do not use a compacted density for loose delivery volume.
For example, 4.5 loose yards with a hypothetical quoted 2,400 lb per loose yard weighs 10,800 lb, or 5.4 US short tons. These numbers are example inputs, not a fill-dirt density range or a maximum weight.
For a carrier-confirmed truck, effective yards per load cannot exceed either its usable volume or its weight capacity divided by the matching lb per yard. With hypothetical limits of 5 cu yd and 8,000 lb of available material payload at 2,400 lb/yd, the weight-limited capacity is 3.333333… yd. The 4.5-yd order needs at least 2 loads, subject to actual axle, route and delivery limits. A generic “tandem” or “single-axle” name is not a verified capacity.
Fill dirt cost benchmarks*
GoodGravel’s September 2026 national published-price sample reports a fill-dirt median of $9 per ton (middle half $6–$11; 34 listings from 16 sites) and $12 per cubic yard (middle half $7–$25; 22 listings from 12 sites). Material only, before delivery. The overall edition covers 68 sites across 26 states and notes that the sample leans toward landscape supply yards because most quarries do not publish prices.2
*National planning figures from a published-price sample, not a local quote or a population-wide average. The reported statistic is a median. Confirm the product, billing volume/weight basis, minimum order, delivery, taxes and fees with your supplier.
At the sample’s $12/yard benchmark, the rounded 4.5-yard example order is $54 material only. This is an arithmetic illustration, not a delivered price. Do not multiply a rounded 4.26 display figure when the supplier will bill 4.5 yards. Ton and yard medians come from different listings; they are not a density conversion for the same product.
FAQ
How much extra fill should I order?
There is no verified universal percentage in this guide. Establish the volume basis, material-specific conversion, any distinct handling allowance and actual sales increment before calculating the final order.
Can any fill dirt go under a slab or behind a wall?
No quantity formula approves a material for a structural or drainage use. Follow the project’s specifications for material, placement and testing; get site-specific advice rather than choosing by the generic product name.
Does 95% compaction mean 5% volume loss?
Do not interpret a compaction specification as a volume-reduction percentage. Ask the project’s geotechnical professional for the defined requirement and the relevant estimating conversion.
Is fill dirt the same as planting soil?
Do not assume a material sold for filling is suitable for the rooting layer. Choose soil and amendments for the planting use separately; see the topsoil guide below.
Related tools and guides
Topsoil and fill dirt volume calculator | Topsoil quantities | Calculate cubic yards | Measure irregular areas
Sources
- Federal Highway Administration: Earthwork Design (volume states, project-specific shrink/swell information and foundation settlement distinction)
- GoodGravel: Gravel Prices by State, September 2026 (published-price sample medians, listing/site counts and sample limitations)