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.
Crusher run and road base are not universal synonyms
Use the product code and project specification to identify each course. A supplier may offer crusher run for a base application, but the name alone does not show compliance with a named road-base specification. Compare grading, fines limits, source material, and any required test results before treating two quotes as equivalent.
FHWA's granular-base overview identifies grading, shape, durability, and fines as material properties that affect performance. The calculator's course names and planning densities do not test those properties or establish a required pavement section.
For each order line, retain the course area and finished thickness, approved product, density and material state, documented yield factor if needed, quote unit, and field allowance. The lift input counts lifts from the maximum thickness you supply; it does not determine a suitable lift thickness for the equipment or aggregate.
Keep clean drainage stone separate from the fines-bearing base and see the crushed-stone grade guide for #57, #8, screenings, and trap rock. Estimate any asphalt surface separately with the Asphalt Calculator.
Worked two-course road-base example
Example values: A 60 ft × 12 ft area with a 6 in lower subbase and 4 in upper base contains 22.22 installed compacted yd³. This example leaves both yield factors at 1.00 and therefore treats the entered 1.50 and 1.55 short-ton densities as installed-state values. A separate 10% field allowance produces 24.44 density-state order yd³ and 37.16 short tons. Three-inch and two-inch maximum lift values produce two lifts for each course; an 18-short-ton usable payload produces three calculated loads. If the supplier instead provides loose delivered density, enter its documented delivered-yd³-per-installed-yd³ factor before using that density.
Volume, density, and supplier units
The installed compacted volume comes directly from the specified course 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
Moisture, gradation, loose-to-compacted change, soft spots, crown, and subgrade correction can alter delivered tons.
Questions specific to this calculation
Which bulk density belongs in the road base 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. In either case, use the exact gradation and moisture condition rather than solid-rock density.