The Formula
Cubic Yards of Gravel = (Length ft × Width ft × Depth in) ÷ 324
Or in feet: (L ft × W ft × D ft) ÷ 27
Example — Standard 12×40 ft driveway at 6" depth:
12 × 40 × 6 ÷ 324 = 8.9 cubic yards
Add 10% waste factor → order 9.8 yards (round up to 10)
Or in feet: (L ft × W ft × D ft) ÷ 27
Example — Standard 12×40 ft driveway at 6" depth:
12 × 40 × 6 ÷ 324 = 8.9 cubic yards
Add 10% waste factor → order 9.8 yards (round up to 10)
Step-by-Step
- Measure length and width of the driveway area in feet
- Choose depth: 4" for light use, 6" for standard residential, 6–8" for heavy vehicles
- Apply formula: L × W × depth(in) ÷ 324 = cubic yards
- Add 10% extra for compaction, waste, and low spots
- Convert to tons if needed: cubic yards × 1.35 = tons
Quick-Reference Size Chart
| Driveway Size | Sq Ft | 4" Depth | 6" Depth | 8" Depth |
|---|---|---|---|---|
| 10×20 ft (single car) | 200 | 2.5 yd3 | 3.7 yd3 | 4.9 yd3 |
| 12×40 ft (standard) | 480 | 5.9 yd3 | 8.9 yd3 | 11.9 yd3 |
| 14×50 ft | 700 | 8.6 yd3 | 12.9 yd3 | 17.3 yd3 |
| 16×60 ft | 960 | 11.9 yd3 | 17.8 yd3 | 23.7 yd3 |
| 20×60 ft (wide/long) | 1,200 | 14.8 yd3 | 22.2 yd3 | 29.6 yd3 |
| 20×100 ft (rural) | 2,000 | 24.7 yd3 | 37.0 yd3 | 49.4 yd3 |
Best Gravel Types for Driveways
| Gravel Type | Best Use | Size | Cost/yd3 |
|---|---|---|---|
| #21A / #411 (base stone) | Base layer; locks together under compaction | 3/4" mixed | €“ |
| Crushed limestone #57 | Top or base layer; excellent drainage | 3/4" | €“ |
| Crushed granite | Premium top layer; attractive finish | 3/4" | €“ |
| Pea gravel | Top layer only; no sharp edges | 3/8" | €“ |
| Decomposed granite (DG) | Compact finish; low dust | Fine | €“ |
💡 Order base and surface gravel separately
Use angular crushed stone (#21A or #411) for the base — angular stones interlock and resist movement. Use a finer decorative gravel for the top 4 inches. Mixing them in one order reduces driveway stability.
Converting Cubic Yards to Tons
- Crushed limestone: 1 yd3 ≈ 1.35 tons
- Pea gravel: 1 yd3 ≈ 1.25 tons
- Crushed granite: 1 yd3 ≈ 1.45 tons
Multiply your cubic yard total by the appropriate factor to convert for suppliers who sell by the ton.
Calculate Your Gravel Automatically
Enter length, width, and depth for instant cubic yards, tons, and cost estimate.
Open Gravel Calculator →FAQ
How many yards of gravel for a 12×40 driveway?
At 6 inches deep: 12 × 40 × 6 ÷ 324 = 8.9 cubic yards. Add 10% waste → order 10 cubic yards. At 4 inches: 5.9 yards.
How many tons of gravel for a 12×40 driveway?
At 6 inches: 8.9 yd3 × 1.35 = 12 tons of crushed stone. Verify with your supplier as they may sell by weight.