Concrete Footings Calculator
Volume and bag count for round footing holes and sono tube forms, per hole and for the whole job.
Results
Worked example
Eight holes at 300 mm diameter and 1.2 m deep. Area of one hole = π × (0.15)² = 0.0707 m². Volume per hole = 0.0707 × 1.2 = 0.085 m³, which is 0.085 ÷ 0.0135 = 6.3 bags per hole. Total volume = 0.679 m³, and total bags = 51.
How it works
Each hole is treated as a straight cylinder: volume = π × (diameter ÷ 2)² × depth. Bag counts use the same yield assumption as our concrete calculator: one 30 kg bag of pre-mix yields about 0.0135 m³ of placed concrete. Bags per hole are shown unrounded so you can plan mixing; the job total is rounded up to whole bags.
FAQ
How deep should footings be in Canada?
Footings must sit below the local frost line, commonly 1.2 m or more in much of Canada, but the required depth is set by your local building code and soil conditions. Confirm before you dig.
What if my footing has a flared bell at the bottom?
This calculator covers straight cylinders only. A bell or Bigfoot-style flare adds volume on top of the result; add roughly 10 to 20 percent or calculate the flare as a separate short cone.
Estimates only. Mississippi Maple provides approximate material estimates for planning. Verify quantities with your supplier or contractor before purchasing, and check local building code and frost depth requirements.