Concrete Column Calculator
Estimate cubic yards, total weight, and 40/60/80-lb bag counts for round concrete columns in seconds. Preview the pour in 3D and plan with less waste.
Round Column Formula, Sonotube Bag Counts, and Ready-Mix Breakpoints
People searching concrete column calculator usually want three things: how to size a round pier from diameter and height, how many bags to buy for sonotube-style pours, and when a repeated post layout stops being a bag job. This section answers those decisions directly instead of treating a column like a slab with a different label.
Diameter to radius: the one conversion people skip
A round column uses π × radius² × height, so the first move is turning diameter into radius. The tool handles that automatically, which removes one of the most common field-math mistakes.
Cubic feet to yards for repeated piers
Small piers are easy to think about in cubic feet, but suppliers quote ready-mix in cubic yards. Once the tool totals all repeated posts, it divides by 27 so the order number is ready to use.
Bag planning for sonotubes and isolated posts
The estimate uses a 150 lb per cubic foot assumption for total weight, then rounds up with the same site logic used elsewhere in the app: about 0.3 ft³ per 40-lb bag, 0.45 ft³ per 60-lb bag, and 0.6 ft³ per 80-lb bag.
When ready-mix beats mixing bags
A single fence pier or deck post may still be a bag job, but repeated columns, taller pours, and drilled holes with messy cleanup can move the project into ready-mix territory faster than people expect.