Estimate crushed stone base for driveways, paths, and patios — cubic yards, tons, and truckloads. Free with steps.
Every durable driveway, paver patio, and shed pad sits on road base — compacted crushed stone that spreads loads, drains water, and stops frost heave. Skimp on the base and pavers sink; over-order and you pay to haul stone away. Our free Road Base Calculator converts your area and desired compacted depth into cubic yards, tons, and estimated truckloads, automatically adding the 30% extra loose material that compaction consumes.
Road base goes by many names — crusher run, road crush, ABC (aggregate base course), MOT Type 1 — but the estimating math is universal: area times depth, divided by 27, times a compaction factor, times the stone’s density. Suppliers sell by the cubic yard or the ton, and the two are linked by roughly 1.4 tons per cubic yard for crushed limestone. The calculator speaks both languages so your estimate matches any quote.
Depth here means compacted depth — the finished, rolled thickness. Because loose stone compacts about 30%, you must order for the loose depth. Four inches compacted needs over five inches loose, and the calculator applies that factor before computing yardage.
Road base (aggregate base course) is a layer of crushed, angular stone — typically 3/4-inch minus, meaning everything from dust up to 3/4-inch pieces — compacted between the soil and the surface. The angular faces interlock under compaction like puzzle pieces, while the fine dust fills the voids, creating a slab-like layer that distributes wheel loads across soft subgrade.
Its three jobs are load spreading, drainage, and frost protection. A car tire presses about 30 psi into the ground; the base spreads that over a wide cone so the soil beneath sees a fraction of it. The voids between stones let water drain instead of pooling, and a deep enough base (below the frost line in cold climates) keeps freeze-thaw cycles from heaving the surface.
Base depth follows the load: 3–4 inches of compacted base under a garden path, 4–6 under a residential driveway, 8–12 under commercial pavement. Each 2-inch compacted lift should be compacted separately — dumping 8 inches at once and rolling the top leaves the bottom loose, which is how driveways develop ruts in year two.
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Density varies by stone type: limestone ~1.4 tons/yd³, granite ~1.5, recycled concrete ~1.3. Ask your quarry for its exact figure if the quote is by the ton.
A driveway is 24 ft long, 10 ft wide, needing 4 inches of compacted base.
Order 4 cubic yards (about 5.5 tons). One small dump-truck load covers it; two trips with a pickup trailer also work.
A patio measures 16 ft by 12 ft with 6 inches of compacted base for a hot tub pad.
Order 5 cubic yards (~6.5 tons). The hot tub’s 4,000+ lb demands the full 6-inch base — this is not the place to value-engineer depth.
Priya’s new 10 × 12 ft shed sat directly on grass, and within a year one corner had sunk 3 inches, racking the door frame. The fix: excavate 6 inches, lay landscape fabric, and install 4 inches of compacted road base. Volume math: 10 × 12 × (4 × 1.3/12) ÷ 27 = 1.93 yd³ ≈ 2.7 tons. Two tons of crusher run, a rented plate compactor for a Saturday, and the shed now sits on a drained, interlocked slab of stone that will outlast the shed itself.
The fabric matters as much as the stone: without it, the base migrates down into soft soil and the soil pumps up into the base — engineers call it “subgrade intrusion,” and it halves the base’s effective life. A $40 roll of woven geotextile under $120 of stone is the highest-ROI forty dollars in the project.
A second scenario: a 200-foot gravel driveway top-dress. The drive is 10 ft wide and needs 2 inches of fresh 3/4-inch stone to restore the crown. Loose depth 2.6 in = 0.217 ft; volume = 200 × 10 × 0.217 ÷ 27 = 16.1 yd³ ≈ 22.5 tons — two tri-axle loads. The crown (center 2 inches higher than edges) is what sheds water; without the top-dress math, most owners order one load, run short at the far end, and leave the wettest section thin.
Highway engineers size base with the AASHTO structural number: each inch of base contributes a structural coefficient (about 0.14 for crushed aggregate) toward the total strength the pavement needs for its design traffic. A residential driveway carrying cars needs a structural number around 2.0; an inch of asphalt contributes ~0.44 and an inch of base ~0.14, so 3 inches of asphalt over 6 inches of base (3×0.44 + 6×0.14 = 2.16) clears the bar. Your driveway math is a simplified version of the same equation states use for interstates.
The California Bearing Ratio (CBR) measures subgrade strength: soft clay scores 2–3, good gravel 20+. On a CBR-2 subgrade, engineers either thicken the base dramatically or stabilize the soil with lime or cement — bridging mush with extra stone alone is expensive and unreliable. If your shovel sinks effortlessly in the native soil, you have a subgrade problem, not a base-quantity problem.
Frost adds a depth rule: in freeze zones, the combined pavement + base should reach a large fraction of the frost depth, or ice lenses will jack the surface. Minnesota driveways sit on 12+ inches of base for this reason; Texas driveways manage with 4. Your local building department’s frost depth, not a national rule of thumb, sets the number.
Recycled concrete aggregate (RCA) deserves a note: it compacts well, drains adequately, and costs 20–40% less than virgin limestone while keeping demolition waste out of landfills. Its density runs ~1.3 tons/yd³ and it can leach high-pH water initially — fine under a driveway, worth knowing near sensitive plantings. For most residential base work, RCA is the smart-money choice.
Road base estimate: loose depth = compacted inches × 1.3; cubic yards = L×W×(loose ft)/27; tons ≈ yd³×1.4 (limestone). Typical compacted depths: paths 3–4 in, driveways 4–6 in, commercial 8–12 in. Compact in 2–3 in lifts; use angular “minus” stone with geotextile on soft subgrade. Source: Sigma Calculator, Road Base Calculator, https://sigmacalculator.net/math-calculators/road-base-calculator/
Cite this page as: Road Base Calculator, Sigma Calculator, https://sigmacalculator.net/math-calculators/road-base-calculator/
Last updated: October 12, 2026