The same volume as 40/60/80 lb bag counts — better for pours under a yard.
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Concrete Yards Calculator
ConcreteQuick answer: ready-mix concrete is sold by the cubic yard, and this calculator turns your slab, footing or column dimensions into yards — including a waste allowance and an estimated delivery cost. A 10×10 ft slab at 4 inches thick needs 1.36 cubic yards with 10% waste, about $204 at $150 per yard before delivery fees.
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Cubic yards to order
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Cubic feet
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Cubic metres
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Equal to 80 lb bags
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Estimated concrete cost
Yards include your waste allowance. Cost is concrete only — most plants add a delivery fee, and orders under about 3 yards often carry a short-load fee.
How it works — the formula
Every ready-mix estimate is a volume problem. For a slab or footing:
Volume (ft³) = Length (ft) × Width (ft) × Thickness (in) ÷ 12For a round column or pier:
Volume (ft³) = π × (Diameter (in) ÷ 24)² × Depth (ft) × Number of columns Cubic yards = ft³ × (1 + waste %) ÷ 27 · Estimated cost = Cubic yards × Price per yardOne cubic yard is 27 cubic feet (0.76 m³). Ready-mix is usually sold in quarter-yard or half-yard steps, so round your order up to the nearest step your plant offers — and order the waste allowance, because a truck that runs short costs far more in a second delivery fee than the extra quarter yard.
Worked examples
| Project | Volume (with waste) | Yards to order | Est. cost at $150/yd³ |
|---|---|---|---|
| Patio slab 10 × 10 ft, 4 in thick, 10% waste | 36.7 ft³ | 1.36 yd³ | $204 |
| Driveway slab 20 × 12 ft, 6 in thick, no waste | 120 ft³ | 4.44 yd³ | $667 |
| 4 deck piers, 12 in Ø × 4 ft deep, 10% waste | 13.8 ft³ | 0.51 yd³ | $77 |
Check the first row by hand: 10 × 10 × (4 ÷ 12) = 33.3 ft³. Add 10% → 36.7 ft³. Divide by 27 → 1.36 yd³. Small job? Below about 1 yard, bags usually win — see the Concrete Bag Calculator for bag counts.
Frequently asked questions
How many cubic yards of concrete do I need for a 10x10 slab?
A 10×10 ft slab at 4 in thick is 33.3 ft³ = 1.23 yd³ exactly, or 1.36 yd³ with 10% waste. At 6 in thick: 1.85 yd³, or 2.04 with waste.
How do I convert cubic feet to cubic yards?
Divide by 27 — a cubic yard is a 3 ft cube, 3 × 3 × 3 = 27 ft³.
How much waste should I add to a ready-mix order?
5–10%. Uneven subgrade, spillage and formwork movement all eat concrete; running short mid-pour is the expensive outcome.
What does a cubic yard of ready-mix cost?
Roughly $130–$180 per yard for standard mixes in the US in 2026, plus delivery and any short-load fee. Enter your plant's quote above for a local estimate.
How many 80 lb bags equal one cubic yard?
45 bags — each 80 lb bag yields about 0.60 ft³, and 27 ÷ 0.60 = 45.
Related tools
Cubic yards and tons for the base layer under your slab.
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Pavers, base gravel and bedding sand for patios and paths.
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Tons and bags of sand for bases, sandboxes and pools.
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See the full list on the Home & DIY Calculators page.
Estimates only. This calculator gives planning volumes for typical residential pours; it is not a structural or engineering calculation. Confirm the order quantity, mix design and delivery terms with your ready-mix plant before pouring.