How Much Gravel for a 20x40 Driveway?

A 20 by 40 foot driveway is 800 square feet. How much gravel for a 20x40 driveway depends on depth: at 4 inches it is about 9.88 cubic yards or 13.8 tons. Suppliers usually sell by the ton, so the tonnage is the number to give them.

Volume and tonnage calculator →

The math for a 20x40 driveway

Area: 20 × 40 = 800 sq ft.
Depth in feet: 4 ÷ 12 = 0.333 ft.
Cubic feet: 800 × 0.333 = 266.7 cu ft.
Cubic yards: ÷ 27 = 9.88 yd³.
Tons: × 1.4 = 13.8 tons.

The volume and tonnage calculator does this for any size.

Gravel needed by depth

Depth	Cubic yards	Tons (approx.)	Tons +10%
2 in	4.94	6.9	7.6
3 in	7.41	10.4	11.4
4 in	9.88	13.8	15.2
6 in	14.81	20.7	22.8

About gravel

Plain gravel is a loose term. Yards use it for rounded bank or river stone as well as for crushed rock, so ask whether the load is washed, crushed or a mix before you lock in a tonnage. If the yard sells by the cubic yard instead of the ton, use the cubic-yard column directly.

Preparing the driveway

Strip sod and soft topsoil, grade for drainage and compact the subgrade before any stone goes down. Gravel drives last longer with a compacted base layer under the top stone and a slight crown so water runs off. Since the driveway carries car and truck traffic, a little extra depth is cheap insurance.

Ordering tips

Round up. Compaction and uneven ground eat material. Adding about 10 percent is common.
Delivery size. 15.2 tons may take more than one typical dump truck load; small loads may carry a delivery fee. See how many tons of gravel in a dump truck.
Bulk vs bags. At this size bulk delivery is usually the practical choice.
Where it drops. Have the truck dump as close to the driveway as firm ground allows.

Where gravel fits

Works well for:

Rural driveways and lanes where low upfront cost matters
Drainage areas and around downspouts
Temporary access while a site is under construction

Less suited to:

Steep slopes, where loose stone washes downhill
Spots plowed often, since plows push gravel into the lawn
Areas next to doors, because stone tracks inside

Quick reference numbers

Per inch over 100 sq ft: about 0.43 tons of gravel (0.31 cubic yards).
Per inch over 1,000 sq ft: about 4.3 tons.
Another size for comparison: a 10x20 area at 4 inches takes about 3.5 tons.
Weight used here: about 1.4 tons per cubic yard.

Mistakes that throw off the order

Forgetting that compaction shrinks loose material. A loose 4-inch spread of a dense-graded stone may finish closer to 3 inches after rolling.
Assuming every supplier uses the same weight. Two yards selling the same product name can quote different tons per yard.
Ignoring the base. A thin surface layer over soft soil fails early no matter how much material is on top.
Using inches as if they were feet. Depth has to be divided by 12 before you multiply; skipping that step inflates the order twelvefold.

Questions people ask

How many tons of gravel for a 20x40 driveway?

About 13.8 tons at 4 inches deep, or 15.2 tons with 10 percent extra.

How many cubic yards is a 20x40 driveway at 4 inches?

About 9.88 cubic yards.

How much does a cubic yard of gravel weigh?

Usually around 1.3 to 1.5 tons, depending on stone size, fines and moisture.

How deep should gravel be for a driveway?

The table above shows 2 to 6 inches. Shallower depths suit top dressing; deeper depths suit new installs and heavier use.

How many square feet is 20x40?

800 square feet.

As an Amazon Associate, AsphaltTons.com earns from qualifying purchases. Product links below are sponsored.