Asphalt is bought by weight, so the job is to turn your area and thickness into tons. Work out the volume, multiply by the mix density, and add a little for waste. Here is the method, the tons-per-yard rule, and how thick to lay it.
The method
Tonnage = area × thickness × density. A 60 × 20 ft driveway (1,200 sq ft / 111 m²) at 3 in (75 mm) is about 11.1 yd³ (8.5 m³) of mix; at roughly 2.4 t/m³ (145–150 lb/ft³) that is close to 22 US tons — order around 23 with a 5% waste allowance.
Tons per cubic yard
About 2 US tons per cubic yard of compacted hot-mix asphalt (roughly 2.4 tonnes per m³), because it weighs around 145–150 lb per cubic foot. So 10 yd³ is about 20 US tons. Densities vary a little by mix and aggregate — your supplier can confirm for their product.
Asphalt Calculator
Enter the area and thickness for the tons and cubic yards of hot-mix, with an optional cost.
How thick to lay it
For a residential driveway, 2–3 in (50–75 mm) of compacted asphalt over a 4–8 in (100–200 mm) compacted aggregate base. Parking lots and roads use 4 in (100 mm) or more, often in two lifts. The base matters as much as the asphalt — size the asphalt here and the base with the gravel calculator.
Hot mix vs cold mix
Hot-mix asphalt (HMA) is laid hot and compacted before it cools — the standard for new driveways and lots, and the most durable surface. Cold mix is for patching potholes and small repairs in cool weather; it is a little lighter and less dense. Pick the matching density so the tonnage is right.
Cost and the minimum load
Hot-mix is usually priced per ton delivered, plus paving labor and the base. Small jobs often carry a minimum-load charge, so a part-load can be billed as a full one — worth asking before you order, since it changes whether a small repair is worth doing in asphalt at all.