01
Formula
Cubic yards = (L × W × depth in feet) ÷ 27.
Order yards = in-place yards × (1 + waste ÷ 100). Bags = order cubic feet ÷ bag yield, rounded up. Cost = order yards × your price per yard. Nothing in that chain is a delivered price.
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Concrete calculator for yards, bags, and slab cost
This concrete calculator turns a length, width, and depth into cubic yards and bags. Use your own price per yard when you want a concrete cost calculator or a concrete slab cost calculator. The price is an input, not a quote.
Concrete to order
6.52cu yd
Area480.00 sq ft
In-place volume5.93 cu yd
Order with waste6.52 cu yd
In-place weight12.00 tons
Bags to order294
Estimated concrete cost$977.78
Planning estimate from the numbers you enter. Coverage, density, waste and price are assumptions, not a supplier quote or an engineering specification.
How it works
Yards come from area times depth.
Multiply length by width to get square feet. Multiply by the depth in feet (inches divided by 12) to get cubic feet, then divide by 27 to get cubic yards. Waste is extra material on top of that in-place volume, because forms, spillage, and an uneven subgrade use more than the neat drawing. An 80 lb bag is treated as 0.60 cubic feet, a common published yield for premixed concrete. Sixty- and forty-pound bags use 0.45 and 0.30 cubic feet. Weight uses 150 pounds per cubic foot, which is 2.025 tons per cubic yard.
02
Example
A 20 by 24 foot slab, 4 inches thick.
The area is 480 square feet and the in-place volume is 160 cubic feet, or 5.93 cubic yards. At 10% waste the order is 6.52 cubic yards. That is 294 of the 80 lb bags, and $977.78 at $150 per yard. Change the price and the cost moves with it.
03
Tips
Order the yards, not the neat volume.
A 4-inch slab is a common residential thickness, not a structural specification. Thickened edges, slopes, and steps are extra. Many ready-mix plants sell by the yard and set their own minimum. Bags make sense for a small pad; a whole slab is usually a ready-mix delivery.
04
Equipment
The pour often needs a machine.
A mixer, a concrete pump, or a skid steer to place stone and move forms is separate from the concrete bill. Dengaro arranges equipment financing from $15,000 to $2 million for business equipment. The button opens that application. It does not price the concrete.
Important questions
Know what to expect.
How does a concrete slab cost calculator work?+
Enter the slab size, the thickness, a waste percent, and the price you expect to pay per cubic yard. The cost line is order yards times that price. It does not include labor, rebar, forms, pump fees, or tax.
Is this a concrete cost calculator for footings too?+
Yes, if you enter the footing as a rectangle: length, width, and depth. A round pier is closer to the cylinder on the volume calculator. Add each shape, then add waste once at the end if you prefer.
How many cubic feet are in a yard of concrete?+
Twenty-seven. That conversion is exact. The bag yields and the 150 pound density are planning factors and can differ by mix.
How do I use the self leveling concrete calculator setting?+
Choose self-leveling, by bag coverage. Enter the floor length and width and the square feet one bag covers at the thickness on the product. The count is area divided by that coverage, rounded up. It is not the cubic-yard math used for ready-mix.
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