Concrete Footing Calculator
Find how much concrete continuous footings, square pad footings and round piers (with or without a bell) need, in cubic yards and bags, with cost.
Change the values and press Calculate to work out your own figures.
Continuous (strip) footing
Enter the footing's total length, width and depth.
Show the working
- volume = length × width × depth
Square or rectangular pads
Enter one pad's size and how many there are.
Show the working
- volume = length × width × depth, per pad
- × 8
Round piers
Enter the pier's diameter and depth, and a bell at the bottom if it has one.
Show the working
- pier = π r² h
- × 6
How to use it
Enter the footing's total length, width and depth. Enter one pad's size and how many there are. Enter the pier's diameter and depth, and a bell at the bottom if it has one.
Lengths can be decimals, fractions or tape entries such as 12' 6 1/2" (in feet or inches). Prices are optional.
Key facts
cubic yards = length × width × depth ÷ 27 (in feet) pier = π r² h; bell = π h ÷ 3 × (R² + R r + r²)
Bags
Premixed bags yield about 0.30 cu ft (40 lb), 0.45 cu ft (60 lb) and 0.60 cu ft (80 lb) of concrete. Ready-mix trucks are usually cheaper above about 1 cubic yard.
Code
Footing sizes depend on the load and the soil; typical house footings are twice the wall's width and at least as deep as the wall is thick, below the frost line. Check your local code.
Questions
How much concrete for 120 ft of 20 × 10 in footing?
6.17 cubic yards.
How much concrete for a 12 in pier 4 ft deep?
0.12 cubic yards (3.14 cu ft).
Formulas
cubic yards = length × width × depth ÷ 27 (in feet) pier = π r² h; bell = π h ÷ 3 × (R² + R r + r²)
Sources
Limitations
- Material densities are typical values (the midpoint of the commonly published range); real loads vary with moisture, grading and compaction, so check with your supplier or type in their density.
- Tank results are the geometric volume; real tanks have wall thickness and fittings.