Guides · Concrete
How Much Does a Yard of Concrete Cover?
By the MyBuildCalcHub team · Figures verified against our audited estimating engine · Updated
The 324 rule, derived once
A cubic yard is 27 cubic feet. Spread over a slab, its coverage is simply volume divided by depth: 27 ÷ (thickness ÷ 12) square feet, which simplifies to 324 ÷ thickness-in-inches. That single constant answers the store-aisle question in either direction, how far a yard goes, or how many yards an area needs. It also explains the intuition contractors carry around: every extra inch of thickness cuts coverage by the same proportional bite, which is why a 6-inch driveway consumes exactly one and a half times the concrete of a 4-inch patio of equal footprint.
Coverage table: one cubic yard, by thickness
| Slab thickness | Coverage per yd³ | Typical use |
|---|---|---|
| 2 in | 162 sq ft | Toppings and overlays |
| 3 in | 108 sq ft | Light-duty pads |
| 4 in | 81 sq ft | Patios, walkways, shed slabs |
| 5 in | 65 sq ft | Light vehicle slabs |
| 6 in | 54 sq ft | Driveways, garage floors |
| 8 in | 40.5 sq ft | Heavy equipment pads |
| 12 in | 27 sq ft | Footings and mass pours |
Worked both directions
Yards to area: a 3-yard ready-mix short load at 4 inches covers 3 × 81 = 243 square feet, a generous patio. Area to yards: a 15 × 20 ft (300 sq ft) patio at 4 inches needs 300 × (4 ÷ 12) ÷ 27 = 3.7 cubic yards, which becomes about 4.1 yards once you add the standard 10% waste buffer. Circular pads follow the same rule once you have the area: a 12-ft round patio is π × 6² = 113 sq ft, so at 4 inches it wants 113 ÷ 81 ≈ 1.4 cubic yards before waste. And in bags rather than truck yards, the 300 sq ft rectangular patio is a daunting 167 × 80 lb bags before waste, the kind of number that settles the bags-or-truck question on its own.
Three coverage traps
Nominal vs. real thickness: coverage math assumes the slab is its stated depth everywhere, but unexcavated or wavy subgrade routinely turns a "4-inch" pour into a 4.5-inch average, a 12% coverage loss that arrives as an empty chute with a corner left to fill. Grade carefully, and keep the waste factor. Thickened edges: many shed and garage slabs carry a deeper perimeter footing; that band covers far fewer square feet per yard than the field of the slab, so compute it separately. Coverage is not strength: stretching a yard thinner to make it "cover more" trades away the slab's load capacity, thickness is a structural spec first and a coverage variable second.
Metric coverage: the 100 rule
The same inversion works in metric with an even cleaner constant. One cubic metre of concrete covers 100 ÷ depth-in-centimetres square metres: 10 m² at a 10 cm slab, 13.3 m² at 7.5 cm, and 6.7 m² at a 15 cm heavy-duty pour. The derivation mirrors the imperial one, a cubic metre spread d metres deep covers 1 ÷ d square metres, and converting the depth to centimetres puts the 100 on top. Working across systems? One cubic yard is 0.76 m³, so a metric quote for the same slab should read about three-quarters of the yardage, a ten-second sanity check on any cross-border spec, and the exact conversion our calculator's Metric (Global) toggle performs automatically.
Frequently asked questions
How many square feet does a yard of concrete cover?
One cubic yard of concrete covers 81 square feet at the standard 4-inch slab thickness. The general formula is 324 divided by thickness in inches: 108 sq ft at 3 inches, 65 at 5 inches, and 54 at a 6-inch driveway depth.
How much area does a yard of concrete cover at 6 inches thick?
A cubic yard of concrete covers 54 square feet at 6 inches thick, exactly two-thirds of its 4-inch coverage, because coverage scales inversely with depth. A single-car driveway pad of 200 sq ft at 6 inches therefore needs about 3.7 yards before waste.
How do I convert coverage back into an order quantity?
An order quantity equals area × (thickness ÷ 12) ÷ 27, plus a waste factor. A 300 sq ft patio at 4 inches is 300 × 0.333 ÷ 27 = 3.7 cubic yards, order about 4.1 yards with the standard 10% buffer, or let the calculator do the whole chain.