Concrete for a 12 × 20 Driveway at 4″
A 12 × 20 ft driveway poured 4 inches thick needs about 3.26 cubic yards (≈ 2.49 m³) of concrete (including a 10% waste buffer) — roughly 147 bags of 80 lb mix, weighing about 6.6 tons. Car driveways are typically 4 inches thick; go thicker for heavy vehicles.
This is over ~1 cubic yard — it fits in one ready-mix truck (~10 cu yd each), and under a full load you may pay a short-load fee. Ready-mix delivery is usually cheaper than mixing 147 bags by hand.
Adjust the numbers
Pre-filled for a 12 × 20 ft slab — change anything to match your project.
A flat, solid pad of concrete — a patio, shed floor, walkway, or driveway. Measure how long and how wide it is, and how thick to pour it (4 inches is typical).
Bag & ready-mix counts include your 10% waste buffer.
Estimate only. These figures help you plan how much to buy — they are not engineering or structural advice. Actual needs vary with site conditions, waste, and installation method, so order a little extra and confirm final quantities with your supplier or contractor before you buy or start the job.
Other driveway sizes
Frequently asked questions
How much concrete do I need for a 12x20 driveway?
A 12 × 20 ft driveway at 4 inches thick contains 80 cubic feet of concrete — about 2.96 cubic yards. With a 10% waste buffer, order 3.26 cubic yards.
How many bags of concrete for a 12x20 driveway at 4 inches?
Roughly 147 bags of 80 lb mix, 196 bags of 60 lb, or 294 bags of 40 lb (including 10% waste). At this size, ready-mix delivery is usually cheaper and easier than mixing bags.
How much does the concrete for a 12x20 driveway weigh?
About 6.6 tons (13,200 lb) of wet concrete.
← Full concrete calculator (slabs, footings, columns & round pads)