Formula
How this estimate works
cubic feet = footing length x footing width x footing depth
A 40 ft footing that is 1.5 ft wide and 1 ft deep needs about 2.44 cubic yards with 10% waste.
Footing volume calculation
For rectangular footings, multiply length by width by depth to get cubic feet. Divide by 27 to convert the result to cubic yards.
Confirm footing dimensions
Footing width and depth are often governed by structure, soil, frost depth, and local code. Use the calculator after the required dimensions are known.
Assumptions used
- Normal-weight concrete is estimated at 150 lb per cubic foot.
- Premix bag yield is estimated from common 40, 50, 60, and 80 lb bag sizes.
- Waste factor is applied after the base volume is calculated.
Before you order materials
- Confirm footing size from plans or code requirements.
- Use quantity for repeated footings with identical dimensions.
- Estimate reinforcement separately from concrete volume.
Frequently asked questions
Is footing depth the same as slab thickness?
No. Footings use width and depth dimensions, while slabs usually use surface area and thickness.
Does this replace code requirements?
No. It estimates material quantity only. Confirm structural and code requirements separately.
Can I estimate several footings at once?
Yes. Use the quantity field when multiple footings have the same dimensions.