Gravel Driveway Calculator

How it works

Each layer is a rectangular slab: length × width × its finished depth gives the compacted volume in place, converted to cubic yards at 27 cu ft per yard. Stone in a truck or stockpile is loose, and it shrinks as it is spread, rolled and driven on, so the loose volume to order is the compacted volume times (1 + compaction factor). The default 17% is the factor the US Army's FM 5-434 lists for converting compacted sand or gravel back to loose volume.

Quarries usually sell by the ton, so the loose volume is multiplied by the material's loose density in tons per cubic yard. Truckloads divide the loose volume by the truck's capacity and round up, at least one for any layer you enter. The driveway length one full truckload covers is the length × the truck capacity ÷ the layer's loose volume, the same spread calculation as the gravel spreading charts in the FHWA Gravel Roads Construction and Maintenance Guide.

Each layer is priced at its own price per ton, and the totals add the two layers. A top course depth of 0 gives a single layer.

Formula

compacted (cu yd) = length × width × (depth ÷ 12) ÷ 27
loose (cu yd)     = compacted × (1 + compaction ÷ 100)
tons              = loose × density (tons per loose cu yd)
truckloads        = max(1, ⌈ loose ÷ truck capacity ⌉)
length per load   = length × truck capacity ÷ loose
cost              = tons × price per ton;  totals = base + top

Example

A 100 ft × 12 ft driveway with 4 in of compacted base stone has 100 × 12 × 4⁄12 = 400 cu ft, or 14.81 cu yd, in place. With a 17% compaction factor that is 14.81 × 1.17 = 17.33 loose cu yd to order; at 1.4 tons per cu yd it weighs 24.27 tons, takes 2 ten-yard truckloads (a full load covers about 57.7 ft of driveway) and costs $970.67 at $40 a ton.

A 2 in top course is half that: 7.41 cu yd compacted, 8.67 cu yd loose, 12.13 tons, one truckload, $546.00 at $45 a ton. Together the two layers are 26 loose cu yd, 36.4 tons, 3 truckloads and $1,516.67.

Assumptions and limitations

• The driveway is a rectangle with uniform layer depths. A curved or flared driveway can be split into rectangles and the results added; a crown, turnaround or thickened apron adds volume not counted here.
• The compaction factor and the densities are typical, editable values, not properties of any particular product. FM 5-434, Earthmoving Operations (US Army, 2000), Table 1-1, converts compacted sand or gravel to loose volume at 1.17, and Table 1-2 lists dry gravel at 2,700–3,000 lb per loose cu yd. The FHWA Gravel Roads Construction and Maintenance Guide (2015), section 3.19, notes volume reductions of 30% or more on gravel roads from placement, grading, moisture and traffic. Grading, moisture and the quarry's product change both figures; the quarry's data govern.
• Truck capacity is in loose cubic yards; a load may instead be limited by the truck's legal weight. Prices are illustrative; delivery charges, taxes, geotextile, excavation and grading are not included.
• Layer depths in the help text are common practice, not a design. A driveway's required thickness depends on the subgrade, drainage and traffic; this is a quantity estimate, not engineering and not a statement of any local code or specification.

Frequently asked questions