Concrete Calculator for Slabs, Footings, Walls and Piers
Enter dimensions to get cubic yards of concrete to order. The calculator converts thickness from inches to feet, divides cubic feet by 27, and adds your waste percentage. Use 5 to 10 percent waste for slabs and 10 percent or more for footings and piers.
Order: 16.00 cubic yards
Net volume 14.81 yd³ (400.0 ft³) · about 720 80-lb bags (including waste) if mixing on site
The formula
Cubic yards = length (ft) × width (ft) × thickness (in) ÷ 12 ÷ 27. For a round pier, volume is π × (diameter ÷ 2)² × height, using feet for every dimension. Multiply by the number of piers.
Kansas tips
- Frost depth: footing depth in Kansas generally runs about 30 inches in the south and 36 inches or more in the northeast. Deeper footings add excavation, formwork and concrete.
- Clay soils: eastern Kansas shrink-swell clays often call for drilled piers, void forms or structural slabs. Read our clay soils guide.
- Exterior exposure: Kansas freeze-thaw cycles make air-entrained concrete the norm for exterior flatwork. Check the project specifications for the required mix.
Need a full concrete takeoff with rebar, forms and accessories? See concrete estimating.
Frequently asked questions
How do I calculate cubic yards of concrete?
Multiply length in feet by width in feet by thickness in feet, then divide by 27. A 40 by 30 foot slab at 4 inches thick is 40 × 30 × 0.333 = 400 cubic feet, or 14.8 cubic yards before waste.
How much extra concrete should I order?
Most Kansas contractors add 5 to 10 percent for flatwork on a good subgrade and 10 percent or more for footings and piers dug in clay, where trench walls are rarely perfectly square.
How deep do footings need to be in Kansas?
It depends on the local code. Frost depth is commonly about 30 inches in south-central Kansas, including Wichita, and 36 inches or more around Kansas City and Lawrence. Always confirm with the building department for your city.
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