Enter your Footing Type (rectangular or round), dimensions like Length, Width, Depth, or Diameter, and a Waste Factor to calculate exactly how much Concrete is Needed — broken down into Cubic Feet and the number of 40 lb, 60 lb, or 80 lb bags to grab from the store.
Concrete Needed
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Cubic Feet
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40 lb Bags
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60 lb Bags
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80 lb Bags
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Calculate the volume by multiplying length × width × depth for rectangular footings, or use π × radius² × depth for circular footings. Convert to cubic yards by dividing by 27.
Footing depth typically ranges from 12-24 inches below the frost line. Most residential footings are 18-24 inches deep, but check local building codes for requirements in your area.
For projects over 1 cubic yard, ready-mix concrete is usually more cost-effective and convenient. For smaller projects or DIY work, bagged concrete offers better control and no minimum orders.
You need approximately 45 bags of 80-pound concrete mix to make one cubic yard. Each 80 lb bag yields about 0.022 cubic yards when mixed.
A 5-10% waste factor accounts for spillage, over-excavation, and measurement variations. It ensures you have enough concrete to complete your project without delays.
Strip footings are continuous foundations that support walls, while pad footings are isolated square or circular foundations that support individual columns or posts.
Footing width should typically be twice the wall thickness. For example, an 8-inch wall needs a 16-inch wide footing. Always consult local building codes for specific requirements.