calcs.homes
calcs.homes
Enter your footing tube's diameter, depth, and how many you need to find total concrete and bag count for your deck posts.
Estimate only — check your local code for required footing depth and diameter.
Each footing is treated as a cylinder — volume = π × radius² × depth — using your entered diameter and depth. We multiply that per-footing volume by your footing count for a job total, then convert to cubic yards and 60 lb bags (about 0.45 cu ft yield each).
Treating footings as simple cylinders matches how sonotube forms actually pour — a cardboard tube filled to a set depth. Footing depth itself isn't really a design choice so much as a code requirement: it's set by your local frost line so the footing base sits below the depth where soil freezes and heaves, which is why depth is the number to confirm with your building department before you dig.
It depends entirely on your local frost line — northern climates often require 42 in or deeper, while frost-free regions may only need a shallow footing. Check with your local building department.
It depends on your beam spans and post spacing — typically posts every 6-8 ft along each beam line. A framing plan or local code table can confirm exact spacing for your deck's size and load.