Published August 11, 2026 · Updated August 23, 2026 · By Tupep
Your supplier quotes tons. Your tape measure gives you square feet. Between those two numbers sit three conversions that people routinely skip, and skipping them is why so many driveway orders come up short by a full truckload.
The three conversions
- Area to in-place volume: cubic yards = (sq ft x depth in inches) / 324
- In-place to loose volume: loose yards = in-place yards x 1.25, because compacted aggregate loses roughly 20 to 25 percent of its loose volume
- Volume to weight: tons = loose cubic yards x density in tons per cubic yard
That 324 comes from a cubic yard being 27 cubic feet. Spread one inch deep it covers 27 x 12 = 324 square feet. Every aggregate estimate starts there.
Base course and surface course are different orders
A gravel driveway is two materials, not one. The base course is a dense-graded product with fines in it, usually crusher run or a similar quarry mix, and its job is to lock together and carry load. The surface course is a cleaner, more uniform stone that drives well and sheds water. Ordering 25 tons of one product and spreading it in one lift gives you a driveway that ruts in the first wet spring.
Worked example: 20 ft x 40 ft
Area = 20 x 40 = 800 square feet.
Base course, 4 inches finished, crusher run at 1.40 tons per cubic yard:
- In place: 800 x 4 / 324 = 9.88 cubic yards
- Loose, with 25 percent compaction allowance: 9.88 x 1.25 = 12.35 cubic yards
- Weight: 12.35 x 1.40 = 17.3 tons
Surface course, 2 inches finished, crushed limestone at 1.35 tons per cubic yard:
- In place: 800 x 2 / 324 = 4.94 cubic yards
- Loose, with a lighter 20 percent allowance since the surface is not heavily compacted: 4.94 x 1.20 = 5.93 cubic yards
- Weight: 5.93 x 1.35 = 8.0 tons
Total: 25.3 tons. We would order 26 tons and keep the remainder for the inevitable low spot at the apron.
The order sheet
| Layer | Material | Finished depth | In-place cu yd | Loose cu yd | Tons |
|---|---|---|---|---|---|
| Base | Crusher run | 4 in | 9.88 | 12.35 | 17.3 |
| Surface | Crushed limestone | 2 in | 4.94 | 5.93 | 8.0 |
| Total | 6 in | 14.82 | 18.28 | 25.3 |
Density by material
Density is where estimates drift. These are the working numbers we use, dry, and every quarry has its own. Ask yours for their conversion factor before you order in volume.
| Material | Tons per cubic yard (dry) | Sq ft per ton at 3 in | Typical use |
|---|---|---|---|
| Crusher run / dense grade | 1.40 | 77 | Base course, compacts hard |
| Crushed limestone, clean | 1.35 | 80 | Surface course, drives well |
| Recycled crushed concrete | 1.30 | 83 | Budget base, compacts well |
| River rock, rounded | 1.30 | 83 | Decorative only, poor traction |
| Washed pea gravel | 1.25 | 86 | Paths, not driving surfaces |
Wet material weighs more. After a heavy rain a stockpile can run 5 to 10 percent heavier, which means a ton buys you less volume. If your load is billed by weight off a rainy stockpile, expect to be slightly short on coverage.
Depth by traffic
| Use | Base depth | Surface depth | Total tons for 800 sq ft |
|---|---|---|---|
| Light car traffic, firm subgrade | 4 in | 2 in | 25.3 |
| Daily use, mixed vehicles | 6 in | 2 in | 33.9 |
| Soft or clay subgrade | 8 in | 2 in | 42.6 |
| Occasional heavy delivery truck | 10 in | 3 in | 55.2 |
How it arrives
- A tandem axle dump truck typically legally hauls 12 to 16 tons. A tri-axle carries roughly 18 to 22 tons.
- Our 26 ton order is two tandem loads or one tri-axle plus a small second delivery. Ask which, because the per load delivery fee is the same whether the truck is full or half full.
- Spread in lifts. Dumping 6 inches at once and driving it in does not compact the bottom of the layer. Two 3 inch lifts, each compacted, gets you a base that holds.
- Ask for a scale ticket. It shows gross, tare, and net weight, and it is the only proof of what you actually received.
Common ways the number comes out wrong
- Forgetting the compaction allowance. Ordering 14.82 in-place yards instead of 18.28 loose yards leaves you almost 20 percent short.
- Measuring the driving lane instead of the finished edge. A 20 foot wide driveway usually gets gravel 21 or 22 feet wide because the edges slough. Add a foot on each side.
- Ignoring the apron and turnaround. A 12 x 20 parking pad off the side is another 240 square feet, which is 7.6 more tons at 6 inches.
- Assuming one density. Using 1.35 for a crusher run order underestimates by about 4 percent, which on 26 tons is a full ton.
The quick field version
For a 6 inch total driveway section, a workable shortcut is one ton per 40 square feet of driveway. Our 800 square feet gives 20 tons, which is conservative against the detailed 25.3 because the shortcut omits the compaction allowance. Use it for a phone quote, use the long math when you actually place the order.
Related guides
- Pea Gravel vs Crushed Stone
- French Drain Gravel Quantity
- How Many Bags of Concrete for a 10×12 Shed Slab
- Bags vs Bulk: The Break-Even Is 8 Yards
Sources and Further Reading
Run your own numbers with the Gravel Calculator, or browse every tool on the calculators index. Coverage figures and material constants are cross-checked against manufacturer technical data sheets before publication. See our Methodology page for how figures are selected and verified.
Planning estimate only. Results assume standard conditions and are intended for material planning. Verify against your product’s technical data sheet and your local building code before purchasing. Structural, electrical, and gas work should be specified by a licensed professional.
Last updated: August 23, 2026
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