Gravel Driveway Calculator: Depth, Layers, and Tons Needed

Updated 2026-08-05 · Yardly

Plan on 8–12 inches of compacted gravel for a real driveway — not the 4-inch patio base — and order about 20% more loose volume than the finished bed, because crushed stone shrinks that much under a plate compactor. Here’s the formula, the layered section that makes it last, and the two details that decide whether you come back next spring with a wheelbarrow or a grader.

The gravel formula

Gravel is sold by the cubic yard (or the ton), but you measure your driveway in feet and the depth in inches. The conversion is the same volume math behind every Yardly calculator:

(Length × Width × Depth ÷ 12) ÷ 27 × 1.20 = loose cubic yards

The ”÷ 12” turns a depth in inches into feet. The ”÷ 27” converts cubic feet to cubic yards. The ”× 1.20” is the compaction margin — dense-graded crusher run loses roughly 15–25% of its loose volume the moment a plate compactor touches it, so you order loose and finish at your target depth. Order the raw compacted number and your 8-inch base finishes at 6½.

The gravel calculator runs this from your dimensions and switches between yards and tons.

Two worked examples:

Single-car, light use — 10×40 ft at 6 inches compacted:

• 400 sq ft × 0.5 ft = 200 cu ft → ÷ 27 = 7.4 cu yd compacted
• × 1.20 = 8.9 loose cu yd → order 9
• × 1.4 tons = ~13 tons

Two-car, standard soil — 14×50 ft at 8 inches compacted:

• 700 sq ft × 0.667 ft = 467 cu ft → ÷ 27 = 17.3 cu yd compacted
• × 1.20 = 20.7 loose cu yd → order 21
• × 1.4 tons = ~29 tons

Depth is set by load, not by area

This is the single biggest misconception carried over from patio math. A patio base is 4 inches because only feet ever touch it. A driveway carries tires, axles, and — if you’re unlucky — a delivery truck or an RV parked for a week. The depth climbs with that load:

• Light use, well-drained soil, occasional car: 6–8 inches total compacted.
• Standard two-car driveway, stable soil: 8–10 inches.
• Frequent trucks/RVs, clay soil, or freeze-thaw climates: 10–12 inches, sometimes more.

Guidance from the Interlocking Concrete Pavement Institute puts driveway base depth well above the 4-inch walking-surface minimum for exactly this reason. Cutting the depth corner is the most expensive mistake in a gravel driveway, because fixing it means pulling up the whole surface.

Build it in layers, not one pile

Unlike a patio — which buries the gravel under sand and pavers — a driveway’s top layer is the driving surface. That changes the material stack. A durable section from the bottom up:

1. Stripped, compacted subgrade. Remove topsoil and organic matter 4–6 inches down until you hit mineral soil, then compact the native ground. Organic material left underneath decomposes and leaves voids that sink.
2. Geotextile fabric on clay, wet, or soft soil. It stops clay fines from pumping up into the stone and stops the stone from sinking into the mud — the “pumping” failure that shows up as settlement within a couple of seasons.
3. Coarse structural base — 4–6 inches of #3 or #4 crushed stone. Large angular rock spreads tire weight over the subgrade.
4. Binding layer — 2–3 inches of #57 or similar. Fills the gaps between the big rocks.
5. Wear surface — 2–3 inches of crusher run (#21A, road base, or dense-graded aggregate). This is the layer tires actually roll on; it packs to a firm, smooth, drivable finish.

So an “8 inches” driveway is really ~4 inches of coarse stone plus ~4 inches of finer graded stone, not 8 inches of one size. The Portland Cement Association makes the same point about proportioning from the bottom up: get the structural volume right first, then choose materials that lock together.

Compact in lifts, and crown it

A plate compactor only densifies the top few inches of stone per pass. Spread the gravel in 2–4 inch lifts and make 4–6 overlapping passes on each one before adding the next. Dumping the full depth and compacting once leaves the bottom loose — and a loose bottom consolidates later, dragging your surface down with it.

Then give the finished base a crown: about ¼ inch of fall per foot from the centerline to each edge (roughly a 2% slope). Water that sheds off the surface is the difference between a driveway that lasts decades and one that potholes in a year. A flat driveway pools, and pooled water is what erodes the base from the top down.

Turning cubic yards into a ton order

Most suppliers sell driveway stone by the ton, so convert before you call:

• Crusher run / dense-graded aggregate: ~1.4–1.5 tons per loose cubic yard.
• #57 / #67 open-graded clean stone: ~1.3–1.4 tons.
• #3 / #4 coarse base stone: ~1.25–1.35 tons.

Using ~1.4 as the average covers most dense-graded driveway mixes. Remember this is the loose density — the same yard weighs more once it’s pounded into place, which is another reason the × 1.20 margin matters.

What not to buy

The smooth, rounded stuff at the garden center — pea gravel, river rock, decorative stone — looks great in a flower bed and fails under a tire. Rounded stone behaves like a box of marbles no matter how long you run the compactor; it never interlocks, so the surface migrates sideways and settles. Use angular crushed stone for every structural layer, and reserve any rounded decorative stone (if you must) only for a thin top dressing you’re willing to rake back into place.

Maintenance is part of the estimate

A gravel driveway isn’t set-and-forget. Expect to top up 1–3 years in, re-grade annually to hold the crown, and re-compact after a wet season that leaves ruts. Budget a little recurring material into the project instead of treating the first delivery as the only one — that habit alone keeps most driveways from sliding into the “rutted mess” category.

Keep reading

• Estimating a patio instead? The gravel calculator for a patio base covers the thinner 4-inch section and the sand layer that goes on top.
• Comparing a gravel driveway to a poured one? The concrete slab calculator totals the cubic yards for a rigid alternative.
• Need to build up a soft subgrade first? The fill dirt calculator sizes the structural fill under the stone.

Frequently asked questions