How Much Asphalt Do I Need?
The short answer: multiply your area by the compacted thickness and the mix density. Here's the full formula, a worked example, and a quick-reference table.
The formula
Asphalt is sold by the ton, but you measure your project insquare feet and inches. The bridge between them is density:
| Volume (ft³) | area (ft²) × thickness (in) ÷ 12 |
| Weight (lb) | volume (ft³) × density (lb/ft³) |
| Tons | weight (lb) ÷ 2000 |
For standard dense-graded hot mix, use a compacted density of145 lb/ft³ as a planning value. Then add a waste allowance (5% is typical) so you don't come up short mid-pour.
Worked example: a 50 × 20 ft driveway at 3 inches
| Area | 50 × 20 = 1,000 ft² |
| Volume | 1,000 × 3 ÷ 12 = 250 ft³ |
| Net weight | 250 × 145 = 36,250 lb |
| Net tons | 36,250 ÷ 2000 = 18.1 short tons |
| Order (＋5% waste) | 18.1 × 1.05 ≈ 19.0 short tons |
That's about two tandem-axle truckloads at the typical 18-short-ton payload, or one tri-axle load. You can verify this instantly with the asphalt calculator.
Quick reference: tons per 100 ft²
At 145 lb/ft³, every 100 ft² of area needs this many net short tons at a given compacted thickness (before waste):
| Thickness | Tons per 100 ft² |
|---|---|
| 2 in | 1.2 |
| 2.5 in | 1.5 |
| 3 in | 1.8 |
| 4 in | 2.4 |
| 5 in | 3.0 |
| 6 in | 3.6 |
So a 600 ft² driveway at 3 inches needs about 600 ÷ 100 × 1.8 ≈10.9 net tons, or roughly 11.5 tons ordered with 5% waste.
The 110 LB/(SY·IN) shortcut
You'll also see the shorthand 110 LB/(SY·IN) — 110 pounds per square yard per inch of thickness. It's the same density expressed differently: 110 lb per square yard-inch equals146.67 lb/ft³. Both give the same tonnage; use whichever your supplier quotes in.
What changes the number
- Density — open-graded mixes compact lighter (~135 lb/ft³); fine-graded heavier (~150). See the density guide.
- Thickness — the single biggest lever. See the thickness guide.
- Waste — irregular shapes and small patches waste more than clean rectangles.
- Base layer — a separate aggregate layer adds tonnage that isn't asphalt. The driveway calculator sizes both layers.
Ready to size your project? Use the asphalt calculator for quantities, or the cost calculator to turn tons into a budget.