Yards, tons, and depths — the driveway math suppliers assume you already know, worked through with real numbers.
Gravel confuses buyers because suppliers quote in two units. The volume math is the same as any fill material: area (sq ft) × depth (ft) ÷ 27 = cubic yards. But delivery trucks are weight-limited, so many yards sell by the ton — and the bridge between the two is density: most common gravel weighs 1.3–1.5 tons per cubic yard, with 1.4 the workable average for pea gravel and crushed stone. A quote in tons divided by 1.4 gives you yards; your yardage times 1.4 gives you tons. Carry both numbers and no quote can confuse you.
Depth does more work than any other choice. Decorative paths ride on 2–3 inches; driveways need 4–6 inches to bear vehicle weight without rutting through to soil. Halving the depth halves the order — which is exactly why underbuilt driveways fail and get re-graveled every two years.
Take a 10 × 40 ft driveway — 400 sq ft. As a simple 4-inch single-layer refresh: 400 × (4 ÷ 12) ÷ 27 = 4.9 cubic yards ≈ 7 tons of #57 crushed stone. At around $50 per cubic yard, that's roughly $245 in material plus delivery.
A new driveway from bare ground is a two-layer build: a 4-inch base of large crushed stone (#3 or #4) that does the structural work, topped with 2 inches of #57 or crusher run that locks into a drivable surface. Same math per layer: the base is 4.9 yards, the top is 2.5 yards — about 7.4 yards (10+ tons) total, or roughly $370–$400 in material at typical crushed-stone prices. Skipping the base layer to save that $245 is the classic false economy: surface stone pushed straight into soil migrates and ruts within a season or two.
Two cheap additions outperform extra stone. On soft or clay-heavy ground, a woven geotextile fabric laid between soil and base stops the stone from migrating downward — which is the main reason gravel driveways "eat" their stone and need re-topping every couple of years. And compact as you build, in 2–3 inch lifts with a plate compactor, rather than dumping the full depth and driving on it; loose-dumped stone settles unevenly and ruts along the wheel paths. Both cost far less than the extra yardage they save over the driveway's life.
One practical note on ordering: bulk deliveries arrive in whole or half yards, and a modest overage beats a second delivery fee. Round the 4.9 up to 5 yards, not down — leftover crushed stone keeps indefinitely and every gravel surface wants topping-up eventually.
Angular stone for anything that bears weight. Crushed stone and crushed limestone ($50–$55 per cubic yard) have fractured faces that interlock under compaction — that's what makes a surface you can drive on. Crusher run (stone with fines mixed in) compacts even tighter and is the standard top course for rural drives.
Round stone for looks and drainage. Pea gravel (~$45 per cubic yard) and river rock (~$75) roll underfoot by design — comfortable for paths and patios, wrong for driveways, ideal in drainage channels and beds where water needs to move. Decomposed granite (~$60) compacts into a firm natural-looking path surface popular in dry climates.
If the project is drainage rather than surfacing — a french drain or a downspout run — the stone choice and quantities work differently; the french drain calculator handles that case, and slope matters more than stone (see the drainage slope guide).
Driveways and paths are easy to trace on satellite imagery — get the real square footage, then let the calculator convert to yards and tons.
Then run the gravel calculator for yards, tons, and cost by stone type, or open the measurement tool directly.