How to use this calculator
- Enter Diameter in in — or tap a preset badge to auto-fill a typical value.
- Enter Height in ft.
- Enter Number of columns.
- Press Calculate. The highlighted row is your order quantity; the note beneath it translates the number into real-world terms.
Formula & constants
Round column volume = π × (diameter ÷ 24)² × height ÷ 27 cu yd. A 12 in sonotube uses one 80 lb bag per 7.7 in of height. Every default in the fields above is editable — when your supplier’s spec sheet lists a different density, coverage rate or price, enter that number instead. The waste and compaction allowances follow common trade practice; see our methodology page for the derivation of each formula and the standards it references.
Where this fits in the project
Concrete work starts below grade: excavation, then a compacted gravel base for drainage, formwork, rebar where the slab spec requires it, then the pour. Order by cubic yard and round up — a short load fee costs more than surplus material.
How this connects to your project
No quantity stands alone — each material in the chain depends on the ones around it. These are the planning steps that pair with the concrete column calculator:
- Concrete Calculator — Columns are vertical concrete elements.
- Concrete Footing Calculator — Columns rest on concrete footings.
- Rebar Calculator — Columns contain vertical rebar cages.
- Deck Calculator — Decks may use concrete columns for support.
- Ready Mix Calculator — Column pours use ready mix concrete.
- Concrete Cost Calculator — Column concrete adds to structural costs.
Frequently asked questions
What size sonotube for a deck post?
10–12 in for typical decks; the footing below often flares wider per code (e.g. Bigfoot forms).
How many bags per foot of 12 in tube?
1.55 bags of 80 lb mix per vertical foot.
Last verified: — prices reflect current national averages. See our methodology.
Estimates are for planning. Material densities, coverage rates and prices vary by region and supplier — confirm final quantities before ordering, and check local code where structural or electrical work is involved.