Concrete Column Calculator
This concrete column calculator helps you find the number of premix concrete bags you need to buy for your building project and determine the amount of ingredients you would need if you decided to mix your own concrete.
Concrete needed0.512 cubic yards13.823 cu ft for 4 × 12 in diameter
Bags of mix2480 lb concrete mix (0.60 ft³)
Each cylinder3.1416 cu ft0.11636 yd³
Radius6 in152.4 mm
Height4 ft1.2192 m
Cross-section area0.7854 sq ft
Weight when cured1.036 US tons
Cubic metres0.39142
The method
volume = π × radius² × height
Radius, not diameter, gets squared
Halve the diameter first. Using the diameter in π r² gives four times the right answer, which is the single most common mistake in column and tube work.
A 12-inch tube 4 feet deep holds about 3.14 cubic feet — roughly a tenth of a cubic yard, or six eighty-pound bags. Footings usually come in multiples, so work out one and multiply.