Free concrete calculator
Concrete Sonotube Calculator
Estimate concrete bags or yards for round column footings like Sonotubes.
- Concrete volume
- 0.51 cu yd
- Volume in cubic feet
- 13.8 cu ft
- 80 lb bags needed
- 24 bags
- Ready-mix short-load fee
- $100
Estimating Notes
- A single 8-inch Sonotube at 4 ft deep holds about 1.4 cu ft of concrete — roughly 3 bags of 80 lb mix.
- A 10-inch tube at 4 ft holds about 2.2 cu ft (4 bags); a 12-inch tube holds about 3.1 cu ft (6 bags).
- Bagged concrete is usually cheaper for a handful of tubes because you skip the ready-mix short-load fee.
- Convert diameter to feet before you calculate: inches ÷ 12. An 8-inch tube is 0.66 ft, a 12-inch tube is 1.0 ft.
- Order about 10% extra — tubes flare slightly at the base and the last bag is never a clean fill.
- Above roughly 20 tubes (about 1 cubic yard total), ready-mix delivery usually beats mixing bags by hand.
Calculator FAQs
How many bags of concrete for a Sonotube?
It depends on diameter and depth. An 8-inch tube at 4 ft deep needs about 3 bags of 80 lb mix, a 10-inch tube about 4 bags, and a 12-inch tube about 6 bags. Enter your exact size above for the precise count.
How many bags for an 8-inch Sonotube?
An 8-inch (0.66 ft diameter) Sonotube holds roughly 0.35 cu ft per foot of depth. At 4 ft deep that is about 1.4 cu ft, or roughly 3 bags of 80 lb concrete once you add a 10% waste allowance.
How many bags for a 10-inch Sonotube?
A 10-inch (0.83 ft) tube holds about 0.55 cu ft per foot of depth. A 4 ft pour needs about 2.2 cu ft — roughly 4 bags of 80 lb mix or 5 bags of 60 lb.
How many bags for a 12-inch Sonotube?
A 12-inch (1 ft) tube holds about 0.79 cu ft per foot of depth. At 4 ft deep that is about 3.1 cu ft, or roughly 6 bags of 80 lb concrete with waste included.
How much concrete is in a Sonotube?
Volume equals π × radius² × depth. For a round tube, cubic feet = 0.7854 × (diameter in ft)² × (depth in ft). Divide by 27 for cubic yards, or by about 0.45 (80 lb) to estimate bags. The calculator above does this for any diameter, depth, and tube count.
When should I use ready-mix instead of bags for Sonotubes?
Bags win for a few small footings — you avoid the $60–$150 short-load fee ready-mix suppliers add on orders under 3 cubic yards. Once your tubes total more than about a cubic yard (roughly 20+ standard footings), ready-mix is cheaper and far less labor than mixing by hand.