Calculate concrete volume in cubic yards and cubic meters, ready-mix truckloads, and pre-mixed bag quantities with customizable waste factor.
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A concrete calculator computes the exact volume of ready-mix concrete required for slabs, foundations, footings, and driveways. It converts square footage and depth into cubic yards and cubic meters, incorporating a standard 10% safety overage for subgrade irregularities and spillage.
\text{Cubic Yards} = \frac{\text{Length (ft)} \times \text{Width (ft)} \times \left(\frac{\text{Thickness (in)}}{12}\right)}{27} \times \left(1 + \frac{\text{Waste}\%}{100}\right)There are 27 cubic feet in one cubic yard. Dividing cubic feet by 27 and adding the waste percentage gives the volume to order from the concrete dispatch plant.
Scenario: Ordering concrete for a 20 ft by 20 ft residential driveway slab poured 5 inches thick with a 10% waste buffer.
Calculate cubic feet: 20 × 20 × (5 ÷ 12) = 400 × 0.4167 = 166.67 cu ft.
Convert to cubic yards: 166.67 ÷ 27 = 6.17 cu yds.
Add 10% contingency: 6.17 × 1.10 = 6.79 cu yds.
Order quantity: 7.0 cubic yards from the ready-mix batch plant.
Multiply Length (ft) × Width (ft) × Thickness (ft), then divide by 27. To convert thickness from inches to feet, divide by 12. For example, for a 10x10 slab at 4 inches: 10 × 10 × 0.333 ÷ 27 = 1.23 cubic yards. Add 10% for waste (1.35 yards).
Normal-weight ready-mix concrete weighs approximately 4,000 pounds (2 US tons) per cubic yard, or about 145 to 150 lbs per cubic foot.
Most ready-mix concrete trucks hold 9 to 11 cubic yards. Ready-mix companies typically require a minimum order of 1 to 3 yards, often charging a "short load fee" for orders under 5 or 6 yards.
As a rule of thumb, if your project requires under 1.5 to 2 cubic yards (~70 to 90 eighty-pound bags), buying bags is typically more cost-effective. For more than 2 cubic yards, ordering a delivery truck saves immense time and labor.
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= 1.13 m³ (40 cu ft net)