How Much Road Base for a 18x40 Driveway?
How much road base for a 18x40 driveway: at 4 inches deep you need about 8.89 cubic yards, which is roughly 13.3 tons at 1.5 tons per yard. The driveway covers 720 square feet, so every inch of depth adds about 2.22 yards.
Volume and tonnage calculator →The math for a 18x40 driveway
- Area: 18 × 40 = 720 sq ft.
- Depth in feet: 4 ÷ 12 = 0.333 ft.
- Cubic feet: 720 × 0.333 = 240.0 cu ft.
- Cubic yards: ÷ 27 = 8.89 yd³.
- Tons: × 1.5 = 13.3 tons.
The volume and tonnage calculator does this for any size.
Road base needed by depth
| Depth | Cubic yards | Tons (approx.) | Tons +10% |
|---|---|---|---|
| 4 in | 8.89 | 13.3 | 14.7 |
| 6 in | 13.33 | 20.0 | 22.0 |
| 8 in | 17.78 | 26.7 | 29.3 |
About road base
Road base (also called base rock, ABC, or Class 2 base in different states) is a graded mix of stone and fines made to compact into a load-bearing layer. Weight per yard is a planning number; the scale ticket at the yard is the real one.
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. This driveway sees car and truck traffic, so match the depth to that load rather than to the minimum.
Ordering tips
- Round up. Compaction and uneven ground eat material. Adding about 10 percent is common.
- Delivery size. 14.7 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 road base fits
Best suited to:
- Base under asphalt and concrete
- Gravel roads and drives
- Equipment and shed pads
Less suited to:
- Drainage layers
- Decorative surfaces
- Surfaces that will stay uncompacted
Quick reference numbers
- Per inch over 100 sq ft: about 0.46 tons of road base (0.31 cubic yards).
- Per inch over 1,000 sq ft: about 4.6 tons.
- Another size for comparison: a 10x20 area at 3 inches takes about 2.8 tons.
- Weight used here: about 1.5 tons per cubic yard.
Common estimating mistakes
- 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.
- Ordering exactly the math. Uneven ground and spillage nearly always need a little more than the flat calculation.
- Skipping drainage. Water sitting under any surface softens the base and leads to ruts and potholes.
Questions people ask
How many tons of road base for a 18x40 driveway?
About 13.3 tons at 4 inches deep, or 14.7 tons with 10 percent extra.
How many cubic yards is a 18x40 driveway at 4 inches?
About 8.89 cubic yards.
How much does a cubic yard of road base weigh?
Usually around 1.4 to 1.65 compacted tons, depending on stone size, fines and moisture.
How deep should road base be for a driveway?
The table above shows 4 to 8 inches. Shallower depths suit top dressing; deeper depths suit new installs and heavier use.
How many square feet is 18x40?
720 square feet.
Related guides
- Crushed Stone vs Gravel: Differences and Best Uses
- Tons to Cubic Yards for Gravel: Conversion Chart
- How Many Tons of Gravel in a Dump Truck? Loads and Coverage
- How Much Does a Ton of Gravel Cover? Depth Chart
- How Much Road Base for a 18x30 Driveway?
- How Much Road Base for a 18x35 Driveway?
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