How Much Asphalt Millings for a 20x40 Parking Pad?

A 20 by 40 foot parking pad is 800 square feet. How much asphalt millings for a 20x40 parking pad depends on depth: at 4 inches it is about 9.88 cubic yards or 12.8 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 parking pad

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: × 1.3 = 12.8 tons.

The volume and tonnage calculator does this for any size.

Asphalt millings needed by depth

Depth	Cubic yards	Tons (approx.)	Tons +10%
3 in	7.41	9.6	10.6
4 in	9.88	12.8	14.1
6 in	14.81	19.3	21.2

About asphalt millings

Millings vary by source: some loads are fine and uniform, others carry chunks. Ask the supplier for a screened product if you want a smoother finish, and check local rules, since some areas restrict their use near water. Weight per yard is a planning number; the scale ticket at the yard is the real one.

Preparing the parking pad

Dig out organic soil, compact the subgrade and set an edge so the stone does not migrate onto the lawn. A pad that holds parked weight for long periods benefits from a dense base under the surface stone. Since the parking pad carries parked vehicles, 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. 14.1 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 parking pad as firm ground allows.

When to choose asphalt millings

Best suited to:

Rural driveways and farm lanes
Parking areas where a dust-free surface is wanted
Low-cost base under a future paved surface

Poor fit for:

Areas near wells or streams where local rules limit them
Decorative or barefoot areas
Jobs needing a uniform, clean look

Quick reference numbers

Per inch over 100 sq ft: about 0.40 tons of asphalt millings (0.31 cubic yards).
Per inch over 1,000 sq ft: about 4.0 tons.
Another size for comparison: a 20x25 area at 2 inches takes about 4.0 tons.
Weight used here: about 1.3 tons per cubic yard.

Where estimates go wrong

Skipping drainage. Water sitting under any surface softens the base and leads to ruts and potholes.
Using inches as if they were feet. Depth has to be divided by 12 before you multiply; skipping that step inflates the order twelvefold.
Mixing up cubic yards and tons. Yards are volume, tons are weight; convert with the product’s weight per yard.
Measuring only the main rectangle. Aprons, turnouts and curved edges add real square footage.

Questions people ask

How many tons of asphalt millings for a 20x40 parking pad?

About 12.8 tons at 4 inches deep, or 14.1 tons with 10 percent extra.

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

About 9.88 cubic yards.

How much does a cubic yard of asphalt millings weigh?

Usually around 1.2 to 1.4 loose tons, depending on stone size, fines and moisture.

How deep should asphalt millings be for a parking pad?

The table above shows 3 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.

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