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How Much Gravel for 40×12 ft at 4 Inches Deep?

40×12 ft of ground at 4 inches needs this much gravel, converted to cubic yards, tons and 50 lb bags. Here is the answer, plus a calculator you can adjust if your measurements are slightly different.

Answer: 5.93 cubic yards

How it changes with depth (in)

Same area, different depth (in):

Depth (in)	2	4	6
Gravel needed	2.96 cubic yards	5.93 cubic yards	8.89 cubic yards
Depth	2 in	4 in	6 in

What 40×12 ft at 4 inches deep actually involves

40×12 ft at 4 in is 8.30 tons, so this is a delivery rather than a collection. The order is roughly 1 full dump-truck load — more than any pickup should carry. Book the delivery and decide where the truck dumps before it arrives: on a driveway it will be in the way, on the lawn it will leave a crater, and on the finished area it is in the wrong place forever.

The area is 480 ft². At 4 in deep that is 160.0 ft³ of stone, or 5.93 yd³. Gravel is sold by weight, so the number that matters at the yard is 8.30 tons, assuming the usual ≈1.4 tons per cubic yard. Everything below is worked out from those figures.

Base course or surface dressing?

4 in is a path and topping depth. It is enough to keep a walking route clean and mud-free, and enough to refresh the surface of a driveway that already has a sound base. For a driveway carrying cars, 4 in on bare ground will rut and disappear into the soil within a season unless it sits on compacted crushed base.

Match the depth to the job rather than picking a number:

Use	Depth	What goes below
Decorative bed, top-up	2 in	woven weed fabric over soil
Garden path, foot traffic	2–4 in	compacted sub-base or fabric
Driveway surface layer	2–3 in	4–6 in compacted crushed base
Driveway base, bare ground	6 in+	geotextile on soft soil

Ordering: bags, tons or trucks

Option	Quantity	Estimated cost
50 lb bags	332 bags	$1,992
Bulk, loose	5.93 yd³ — 8.30 tons	$267
Pickup collection	12 trips	$267 + fuel
Dump truck delivery	1 load	$267 + delivery
Perimeter edging	110 lin ft	40 ft + 12 ft doubled, plus 5% for corners

The area is 40 ft × 12 ft, so the longest single run is 40 ft and the short side is 12 ft. Rake in strips along the long run rather than across it — you will do fewer, longer passes and the surface comes out more even. Perimeter edging is about 110 linear ft.

Bulk comes to about $267 for 5.93 yd³ against $1,992 in 50 lb bags — a large saving that gets bigger as the order grows. Bagged stone only makes sense when the quantity is tiny or the truck cannot reach the spot.

Costs assume $6 per 50 lb bag and $45 per cubic yard loose. Weight uses 1.4 US tons per cubic yard, though decorative and lighter stone runs nearer 1.25 and dense crushed rock up to 1.45. Delivery and minimum-order charges are local, so get a delivered price before you decide.

Laying gravel so it stays put

Strip the topsoil. Gravel spread over grass or soft earth sinks within a season — the soil pumps up through it and the surface turns to mush.
On soft ground lay a woven geotextile before any stone. It separates the stone from the soil so the two do not mix, and it does most of the work of keeping the surface firm.
Build in lifts. Compact each ≤4 in layer with a plate compactor before the next, and water it lightly as you go so the fines bind.
You are moving 8.30 tons — about 5.93 yd³. Work from the far end back toward the entrance so you are not walking on the finished surface.
Edge it, or it will migrate into the lawn. Timber, steel strip or a shallow concrete curb all work; without an edge the stone spreads a little further every month.
Weed fabric belongs under decorative beds, not under a driveway base: traffic tears it, and once it rucks it creates a soft spot right where you need the surface firmest.

Common questions

How much gravel for 40×12 ft at 4 inches deep?

About 5.93 cubic yards, or 8.30 tons. The area is 480 ft² and 4 in deep gives 160.0 ft³ of stone; dividing by 27 gives cubic yards and multiplying by 1.4 gives the tonnage. That is roughly 332 × 50 lb bags if you buy bagged.

How many tons are in a cubic yard of gravel?

Roughly 1.4 US tons. It ranges from about 1.25 tons for lightweight decorative stone to 1.45 for dense crushed rock, and wet stone weighs more than dry. This calculator uses 1.4, a safe middle figure. At this depth one cubic yard covers about 81 ft².

How many pickup loads is 8.30 tons of gravel?

About 12 trips allowing half a cubic yard per trip. Be careful here: a half-ton pickup is rated for about 1,000 lb, which is only 0.35 cubic yards, and a full load of stone is well over that. Check your payload sticker rather than filling the bed.

How deep should gravel be for a driveway?

Six inches of compacted crushed base for a driveway, placed in lifts and compacted between them, topped with two to three inches of decorative stone if you want a finished look. Paths need two to four inches. This page is worked at 4 in — 4 in is a path and topping depth.