Formula used
Installed compacted yd³ = length × width × (compacted course depth ÷ 12) ÷ 27
Density-state yd³ = installed compacted yd³ × documented loose-to-installed yield factor (use 1.00 for installed-state density)
Order yd³ = density-state yd³ × (1 + stated field allowance ÷ 100)
Course short tons = order yd³ × density for that same state
Lifts = compacted course depth ÷ maximum compacted lift depth, rounded up
Combined payload lower bound = total short tons ÷ usable truck payload, rounded up
Separate product loads = rounded-up base loads + rounded-up surface loads
Reference basis: fixed unit conversions follow the NIST SI conversion tables. Bulk density is product- and condition-specific; the FHWA Field Materials Manual documents aggregate sampling and moisture-density testing; supplier or project data for the actual product and condition should replace the planning preset when available. The USGS aggregates program is used for aggregate terminology and scope. Read the full methodology and limitations.
Worked two-course driveway example
Example values: A 50 ft × 10 ft driveway with a 4 in lower base and 2 in upper surface contains 9.26 installed compacted yd³. This example leaves both yield factors at 1.00 and therefore treats the entered 1.55 and 1.60 short-ton densities as installed-state values. A separate 10% field allowance produces 10.19 density-state order yd³ and 15.96 short tons. A 3 in lower-course lift limit produces two lifts; the base requires 10.5247 short tons and the surface requires 5.4321 short tons. Their combined weight fits within one 18-short-ton payload, but plan two loads when the products are delivered separately. Use a single mixed or split delivery only if the supplier confirms that arrangement. If a supplier instead quotes loose delivered density, replace 1.00 with that supplier’s documented delivered-yd³-per-installed-yd³ factor before using the quote density.
Volume, density, and supplier units
The installed compacted volume comes directly from the design depth. A delivered loose-yard result appears only through the entered supplier yield factor. Multiply by a density only when it describes the same displayed volume state, then apply the field allowance once on the basis stated above.
Field conditions that change tonnage
Ruts, crown, shoulders, soft subgrade, compaction, and angular versus rounded aggregate change the real delivered quantity.
Questions specific to this calculation
Which bulk density belongs in the gravel driveway tons estimate?
Use an installed-state density when the yield factor is 1.00. If the supplier density describes loose delivered yards, enter its documented loose-delivered-yards-per-installed-yard factor first. Measure changing widths or depths as separate segments, and keep lower and upper courses separate.