How many square feet does a yard of concrete cover?
One cubic yard of concrete covers 81 square feet at 4 inches thick: a 9 × 9 ft slab. At 5 inches it covers 64.8 square feet, and at 6 inches, 54.
How to work it out
- 1 cu yd × 27 = 27 cu ft ÷ (4 in ÷ 12 = 0.333 ft) = 81 sq ft
- Shortcut: 324 ÷ 4 in = 81 sq ft per cubic yard
Eighty-one square feet is the number most contractors carry in their heads. Everything else follows from it: thinner goes further, thicker less, in exact proportion.
Adjust for your project
- As a square slab
- 9 × 9 ft
- Same volume in 80 lb bags
- 45 bags
One cubic yard at other thicknesses
| Thickness | Area covered | As a square slab |
|---|---|---|
| 2 in | 162 sq ft | 12.7 × 12.7 ft |
| 3 in | 108 sq ft | 10.4 × 10.4 ft |
| 3.5 in | 92.6 sq ft | 9.6 × 9.6 ft |
| 4 in | 81 sq ft | 9 × 9 ft |
| 5 in | 64.8 sq ft | 8 × 8 ft |
| 6 in | 54 sq ft | 7.3 × 7.3 ft |
| 8 in | 40.5 sq ft | 6.4 × 6.4 ft |
Where 81 comes from
A cubic yard is 3 ft × 3 ft × 3 ft, or 27 cubic feet. Spread to 4 in — a third of a foot — those 27 cubic feet cover 27 ÷ ⅓ = 81 square feet. The quick version, 324 ÷ thickness in inches, works for any thickness: 324 ÷ 6 = 54.
In practice you get a little less. A base that dips a quarter inch in the middle of a 4 in slab eats about 6% of the concrete, and some always stays in the chute and wheelbarrows. NRMCA suggests ordering 4–10% more than the calculated volume for that reason.
From coverage to an order
Turn it round to size an order: a 10 × 10 slab (100 sq ft) at 4 in is 100 ÷ 81 = 1.23 yards, before any extra — worked through on how much concrete for a 10×10 slab. In bags, one yard is 45 of the 80 lb size; see how many 80 lb bags of concrete in a yard.
Different size? Use the full Yards of Concrete to Square Feet.
What you’ll need
- Aluminum screedMid-range price
A straight, light screed strikes off the concrete level with the forms. A straight 2×4 works too if it really is straight.
See options on Amazon (opens in a new tab) - Bull float with handleMid-range price
Smooths and levels a slab you can’t reach across, right after screeding. Rent or buy one for anything wider than about 6 ft.
See options on Amazon (opens in a new tab)
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Frequently asked questions
How many square feet does a yard of concrete cover at 6 inches thick?
54 square feet: a 7.3 × 7.3 ft square.
How many square feet does a yard of concrete cover at 5 inches thick?
64.8 square feet, a square roughly 8 × 8 ft.
How much area do 5 yards of concrete cover at 4 inches?
405 square feet, a square roughly 20.1 × 20.1 ft.
Sources
- NIST Handbook 44, Appendix C — General Tables of Units of Measurement (opens in a new tab) — 1 cubic yard = 27 cubic feet; 1 cubic foot = 1,728 cubic inches.
- Quikrete Concrete Mix (No. 1101) data sheet (opens in a new tab) — Yields: 40 lb ≈ 0.30, 50 lb ≈ 0.375, 60 lb ≈ 0.45, 80 lb ≈ 0.60, 90 lb ≈ 0.675 cu ft; unit weight ≈ 140 lb/cu ft; for pours 2 in thick or more; 6–9 pints of water per 80 lb bag; control joints every 6–8 ft; cure 5 days at 70 °F or above, 7 days at 50–70 °F; protect from freezing for 48 hours.