How much gravel do I need for a 12x20 driveway at 4 inches?

A 12 ft x 20 ft area at 4 in deep is 80 cubic feet, or 2.96 cubic yards. At a typical crushed-stone weight of 2,800 lb per cubic yard, that is about 4.15 tons (3.76 metric tonnes).

How do I convert cubic yards of gravel to tons?

Multiply cubic yards by the weight per cubic yard, then divide by 2,000. Typical weights per loose cubic yard: crushed stone about 2,800 lb, pea gravel about 2,700 lb, river rock about 2,600 lb, screened topsoil about 2,000 lb. The calculator above does this with whichever density you pick.

How deep should a gravel driveway be?

For a new driveway over bare ground, plan 4 to 6 inches after compaction, usually in two layers: a coarse base, then a finer top layer 2 to 3 inches deep. For topping up an existing gravel driveway, 2 inches is the usual refresh depth.

Is a ton of gravel the same as a cubic yard?

No. A cubic yard is a volume (3 ft x 3 ft x 3 ft); a ton is 2,000 lb. For most crushed stone one cubic yard weighs about 1.3 to 1.5 tons, so quarries quote both — always order by the unit they price.

Gravel Calculator

Enter your area and depth to get cubic yards, tons and tonnes — before you call the quarry.

The short answer

Formula. Cubic feet = length × width × (depth in inches ÷ 12); cubic yards = cubic feet ÷ 27; tons = cubic yards × lb-per-cubic-yard ÷ 2,000.

Example. A 12 ft × 20 ft drive topped 4 in deep with crushed stone (about 2,800 lb per yard) takes 80 cubic feet = 2.96 cubic yards = about 4.15 tons.

Area & depth

Length × width I know the square footage

Length (ft)

Width (ft)

Depth (in)

New driveway: 4–6 in. Topping up: 2 in.

Material

Weight per cubic yard (lb)

Best answer: ask your quarry for their number.

Price per ton (optional)

How this calculator works

Gravel is sold two ways: by volume (the cubic yard — a box 3 ft × 3 ft × 3 ft) or by weight (the ton, 2,000 lb, or the metric tonne, 1,000 kg). The math here connects the two. First the volume: your area in square feet times the depth in feet (depth in inches ÷ 12) gives cubic feet; divide by 27 to get cubic yards. A 12 × 20 ft driveway at 4 in deep is 12 × 20 × (4 ÷ 12) = 80 cubic feet = 2.96 cubic yards.

Then weight: one loose cubic yard of crushed stone typically runs about 2,800 lb — so 2.96 yards is roughly 8,300 lb, about 4.15 tons. Pea gravel and river rock are a little lighter per yard, sand can swing widely with moisture, and topsoil is around a ton per yard. These densities are typical loose figures, not constants of nature: the dropdown presets are editable, and the single best improvement you can make is to phone the quarry and ask what a yard of their material actually weighs. Order by whichever unit they price — most quote per ton delivered, some per yard scooped.

Two practical wrinkles the arithmetic hides. Gravel compacts: a freshly spread 4-inch layer settles, so for a new driveway over soft ground, spreading 5 inches to end up with 4 after rolling is normal. And delivery is charged by the truckload: a full-size dump truck carries around 10–15 cubic yards, with a minimum delivery fee below that, so it is often the truck size, not the tonnage, that sets your real cost. For small jobs, half-yard bags and pickup loads are sold by the scoop (typically a half or full yard).

Sources & review date

Densities are typical published supplier figures (crushed stone about 2,800, pea gravel about 2,500, topsoil about 2,000 lb per cubic yard) — editable presets on the page.

Last reviewed: October 2026. Numbers that drift (fees, prices, densities) are editable inputs on this page.

Gravel FAQs

How many tons are in a cubic yard of gravel?

About 1.3 to 1.4 tons for crushed stone, a little less for pea gravel or river rock. Multiply the yards by the pounds-per-yard from the table above and divide by 2,000 — or just let the calculator do it.

How deep should gravel be to stop weeds and ruts?

4 to 6 inches over a compacted base is the standard driveway build. Thinner layers migrate and rut; much deeper than 6 inches of loose stone makes steering awkward and wastes material. A geotextile fabric under the base layer does more for weeds than extra depth.

How do I work out a circular area?

Use the square-footage mode: the area of a circle is 3.1416 × radius × radius (radius = diameter ÷ 2). A 10-ft circle is about 78.5 sq ft — type that in with your depth and you are done.

Why does the same gravel weigh different amounts at different times?

Moisture and how loosely it is scooped. Wet gravel and packed gravel weigh more per yard than dry loose gravel — one more reason the quarry's own figure beats any published table.

Assumptions this tool makes: the area is flat and the depth is even; densities are typical loose weights (crushed stone 2,800, pea gravel 2,700, river rock 2,600, dry sand 2,700, screened topsoil 2,000 lb per cubic yard — reviewed October 2026, all editable); compaction and delivery minimums are not included. Estimates are for planning — confirm quantities and price per unit with your supplier before ordering.