Concrete for a 20 × 20 Patio at 4″
A 20 × 20 ft patio poured 4 inches thick needs about 5.43 cubic yards (≈ 4.15 m³) of concrete (including a 10% waste buffer) — roughly 245 bags of 80 lb mix, weighing about 11 tons. A 4-inch slab is standard for a residential patio.
This is over ~1 cubic yard — it fits in one ready-mix truck (~10 cu yd each). Ready-mix delivery is usually cheaper than mixing 245 bags by hand.
Adjust the numbers
Pre-filled for a 20 × 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 patio sizes
Frequently asked questions
How much concrete do I need for a 20x20 patio?
A 20 × 20 ft patio at 4 inches thick contains 133.33 cubic feet of concrete — about 4.94 cubic yards. With a 10% waste buffer, order 5.43 cubic yards.
How many bags of concrete for a 20x20 patio at 4 inches?
Roughly 245 bags of 80 lb mix, 326 bags of 60 lb, or 489 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 20x20 patio weigh?
About 11 tons (22,000 lb) of wet concrete.
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