Free driveway gravel calculator: enter driveway length, width and gravel depth to get gravel volume in cubic feet, cubic yards and tons, with a waste allowance.
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Measure driveway length and width in feet and the gravel depth in inches, then add a waste allowance for compaction and uneven ground (10 percent is a sensible default). The calculator returns volume in cubic feet and cubic yards, because bulk suppliers sell by the yard, and weight in tons, because delivery trucks are rated by weight.
A driveway is a flat box, so volume is length times width times depth, with depth converted from inches to feet by dividing by 12. A 20 × 12 foot driveway at 4 inches deep is 20 × 12 × (4 / 12) = 80 cubic feet before waste. With a 10 percent allowance that becomes 88 cubic feet, which is 88 / 27 = 3.26 cubic yards, and at about 1.4 tons per cubic yard that is 4.56 tons of crushed stone. Ordering by the yard and checking the truck weight both come from the same volume. Coverage tables from suppliers list the same volume in cubic yards, and gravel types differ mainly in stone shape and size, not in the volume formula.
Measure the longest and widest points, and for a curved or L-shaped drive split it into rectangles and add the results, or run the calculator once per section. Enter the finished gravel depth, not the excavation depth: a typical build is 4 inches of gravel over a compacted base, not 4 inches total from bare soil. Keep the waste allowance at 10 percent unless the ground is very uneven, where 15 percent is safer.
For a light car driveway, 4 inches of compacted gravel over a firm base is the usual minimum, and 6 inches lasts longer on soft or clay ground. Heavy vehicles and turning areas deserve 6 to 8 inches. Depth matters more than stone size for durability: a thin layer ruts quickly no matter how good the stone is, while a properly compacted 6 inch layer spreads wheel loads and drains better.
A single-car drive, 20 × 10 feet at 4 inches with 10 percent waste, needs about 73 cubic feet, 2.72 cubic yards and 3.81 tons. A two-car drive, 20 × 20 feet at 6 inches with 10 percent waste, needs 220 cubic feet, 8.15 cubic yards and 11.41 tons. A long farm drive, 100 × 12 feet at 4 inches with no waste allowance, needs 400 cubic feet, 14.81 cubic yards and 20.74 tons, which is more than one standard truckload, so split delivery across days. A 10x20 driveway at 4 inches needs 2.47 cubic yards, about 3.5 tons at 1.4 tons per yard. A 100 foot driveway, 10 feet wide at 4 inches, needs about 12.3 cubic yards and 17 tons. One ton of gravel covers about 50 square feet at 4 inches deep, which is how many cubic yards in a ton of gravel converts to coverage: roughly 0.7 cubic yards per ton.
Crushed stone with angular faces locks together and stays put under tyres, which is why it is the standard driveway surface. Pea gravel looks softer but rolls underfoot and migrates, so it suits paths better than drives. Ask the supplier whether the price is per cubic yard or per ton, confirm the stone size (3/4 inch crushed is the common driveway grade), and compare delivered totals, because delivery often costs as much as the stone on small orders. The best gravel for a driveway is angular crushed stone, and the cheapest gravel for a driveway is usually crusher run, which compacts into a firm base. Both beat round stone for a surface cars actually drive on.
Multiply length × width × depth (in feet) and divide by 27 for cubic yards, then add 10 percent for waste. A 20 × 12 foot drive at 4 inches needs about 3.26 cubic yards with waste. Enter your exact size above.
About 1.4 tons for crushed stone, though it varies with stone type and moisture. This calculator uses 1.4 tons per cubic yard, so 3.26 cubic yards is about 4.56 tons.
Four inches compacted is the minimum for cars, 6 inches is better on soft ground, and 6 to 8 inches suits heavy vehicles and turning areas. Thin gravel ruts fast, whatever the stone.
Crushed stone, because its angular faces lock together under tyres. Pea gravel is round, rolls, and migrates to the edges, so it is better for garden paths than driveways.
Yes, 10 percent is the usual allowance for compaction, uneven ground and spillage. On very uneven or soft ground use 15 percent. The calculator adds your chosen allowance before converting to yards and tons.
Split the shape into rectangles, calculate each one, and add the volumes. For a curve, measure it as a series of short rectangles along the curve and add them up.
Stone itself is often sold by the cubic yard or ton, and delivery can add a large share on small orders. Get a delivered quote for your exact cubic yards, and compare suppliers on the delivered total, not the stone-only price.