Work out how much gravel, pea gravel, crushed stone or river rock a driveway, path or bed needs, in cubic yards, in tons and in bags, using the depth you are spreading and the density of the stone.
Depth is the number people get wrong. Measure the layer you are actually spreading, not the excavation depth, and remember that a compacted base swallows about 15% more stone than the same loose volume.
You measure a rectangle, you order by weight, and in between sit two conversions. Volume is length × width × depth with the depth converted to feet. Divide by 27 for cubic yards. Multiply by the stone's density in tons per cubic yard to get the tonnage your supplier actually quotes.
There is a shortcut worth remembering: for any area in square feet and any depth in inches, cubic yards = (sq ft × depth in inches) ÷ 324. The 324 comes from 27 cu ft × 12 in. At 1 in deep one cubic yard covers 324 sq ft; at 2 in it covers 162; at 4 in it covers 81.
Density is the fudge factor. Loose decorative pea gravel is around 1.4 tons per cubic yard; a dense crusher run with fines is closer to 1.7. On a 20-ton order that difference is most of a delivery, so ask your supplier for their figure rather than assuming.
| Depth | Per cubic yard | Per ton (≈1.4 t/yd³) | Typical use |
|---|---|---|---|
| 1 in | 324 sq ft | ~231 sq ft | Thin decorative scatter over fabric |
| 2 in | 162 sq ft | ~116 sq ft | Decorative cover, garden paths |
| 3 in | 108 sq ft | ~77 sq ft | Usual walkway depth |
| 4 in | 81 sq ft | ~58 sq ft | Standard driveway surface |
| 6 in | 54 sq ft | ~39 sq ft | Driveway or shed base, in lifts |
Coverage is inversely proportional to depth, so doubling the depth exactly halves the coverage, the tonnage doubles for the same area.
| Material | Typical density | Best for |
|---|---|---|
| Pea gravel (1/4–1/2 in) | 1.2–1.4 t/yd³ | Walkways, playgrounds, decorative beds, drainage |
| Regular gravel (1/4–2 in) | 1.4–1.7 t/yd³ | General fill, drainage |
| #57 crushed stone (3/4–1 in) | 1.35–1.6 t/yd³ | Driveways, French drains, pipe bedding |
| Crusher run / road base | 1.65–1.9 t/yd³ | Driveway base, paver base, compaction |
| River rock (2–6 in) | 1.5–1.7 t/yd³ | Decorative features, stream beds, erosion control |
| Decomposed granite | 1.2–1.4 t/yd³ | Paths, patios, landscape accents |
For general estimating, 1.5 tons per cubic yard is a safe planning figure across most standard gravels. One ton works out at about 0.71 cubic yards.
This setting matters more than it looks. Loose fill keeps roughly the volume you poured, decorative rock, French drain stone, a top layer over fabric. Compacted base consolidates about 15% under a plate compactor or roller, so the same excavation swallows noticeably more material than its open volume suggests.
Use compacted for anything that will bear load: paver and patio bases, shed pads, driveway lifts, post backfill. Getting it wrong in the cautious direction costs a wheelbarrow of surplus; getting it wrong the other way stops a paver job halfway through with the base an inch shy of grade.
Compact in lifts of about 2 in, and water each lift lightly if the stone is dusty. Pouring a slab on top? The compacted stone is the layer under the slab, never a substitute for it.
The volume arithmetic comes from the definition of the cubic yard as 27 cubic feet, which gives the 324 ÷ depth-in-inches coverage shortcut. Density ranges are the standard published figures for the common aggregate gradations, about 1.4 tons per cubic yard for loose pea gravel rising to 1.7–1.9 for crusher run and road base, and are what suppliers and quarries quote against. The 15% compaction allowance reflects the consolidation of a plate-compacted base; it is a planning allowance, not a universal ratio. Depth guidance follows ordinary landscape and paving practice. Density genuinely varies with the pit, the gradation and how wet the stone is, so confirm the figure with your supplier before ordering by the ton.
Multiply length × width by the depth in feet to get cubic feet, then divide by 27 for cubic yards. A 40 × 12 ft driveway at 4 in deep is 480 sq ft × 0.333 ft = 160 cu ft, or 5.9 cubic yards. At 1.5 tons per cubic yard that is about 8.9 tons before waste.
It depends entirely on depth. At a typical 1.4 tons per cubic yard, a ton covers about 231 sq ft at 1 in deep, 116 sq ft at 2 in, 77 sq ft at 3 in and 58 sq ft at 4 in. The common rule of thumb is one ton covers roughly 100 sq ft at about 2½ in.
Roughly 1.4 tons for loose pea gravel, 1.5 for regular gravel and 1.65–1.9 for crusher run and road base. Density varies with the pit and the gradation, so treat these as planning values and ask your supplier for their number.
Four inches of surface gravel is the usual residential baseline for light vehicle traffic. Heavier use or a soft subgrade wants 4 in of compacted road base plus 2 in of surface stone, or up to 6 in total. Compact in 2 in lifts.
Four inches of compacted base for a patio or walkway and 6 in for a driveway, with a nominal 1 in bedding sand on top. Excavate deep enough for the base, the sand and the paver thickness, plus about an inch below the finished grade so the surface drains away from the building.
About 40. A standard 0.5 cubic foot bag of pea gravel weighs roughly 50 lb, so 2,000 lb is around 40 bags. Bagged gravel is far more expensive per ton than bulk delivery, it makes sense for small fills and for places a truck cannot reach, not for a driveway.