How to calculate asphalt
Asphalt is measured by volume, then converted to weight because it's sold by the ton. Multiply length, width, and depth in feet for cubic feet, then apply the density:
Tons = (Length ft × Width ft × Depth ft × density) ÷ 2000
A 50 ft × 20 ft area at 3 inches deep is 250 cubic feet. At 145 lb/ft³ that's 36,250 lb, or about 18 tons of hot-mix asphalt.
Typical depths
- Residential driveway: 2–3 in of asphalt over a compacted base.
- Parking lot / light commercial: 3 in or more.
- Heavy traffic: 4+ in, often in layers.
Order a little extra
The waste field defaults to 5% to allow for compaction and uneven sub-base. Asphalt must be laid and rolled while hot, so running short mid-job is costly — a small surplus is cheap insurance.
Frequently asked questions
How do I calculate how much asphalt I need?
Multiply the length, width, and depth in feet to get the volume in cubic feet, then convert to weight using asphalt's density (about 145 lb per cubic foot). A 50 ft × 20 ft area paved 3 inches deep is 250 cubic feet, or about 18 tons of hot-mix asphalt.
How much does a ton of asphalt cover?
At a 2-inch depth, one ton of hot-mix asphalt covers roughly 80 square feet; at 3 inches, about 53 square feet. Coverage drops as the layer gets thicker, since more material fills the same area. This calculator works it out from your exact depth.
How thick should an asphalt layer be?
Residential driveways are usually 2–3 inches of asphalt over a 4–8 inch compacted aggregate base. Parking lots and areas carrying heavier vehicles need more — often 3–4 inches or built in layers. Always confirm with your paving contractor and local requirements.
Does asphalt density vary?
Yes. Hot-mix asphalt typically runs 140–150 lb per cubic foot (about 2,025–2,160 lb per cubic yard) depending on the mix and aggregate. This calculator defaults to 145 lb/ft³; adjust it if your supplier quotes a different density.
Disclaimer: Asphalt density varies by mix, so tonnage is an estimate. Confirm quantities and the base requirement with your paving contractor.