Sonotube Concrete Calculator

Sonotube concrete calculator: estimate concrete for a round column in cubic feet, cubic yards, and 60 or 80 lb bags. Free, runs in your browser, no signup.

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Every figure above is calculated locally in your browser from the assumptions shown. No inputs are sent anywhere. See the methodology section below for the formulas used.
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Planning estimate only, not financial, tax, or legal advice. Verify assumptions and current rules before making decisions.

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What does this calculator estimate?

One 12-inch diameter, 4-foot tall sonotube holds about 3.14 cubic feet, or 0.128 cubic yards, of concrete. With 10% waste that is 8 bags of 60 lb mix or 6 bags of 80 lb. Enter diameter, height, and tube count in the BoringToolsKit sonotube calculator for your bag count.

  • A 12 in x 4 ft column is 3.14 cubic feet: pi x radius squared x height. (Source: BoringToolsKit calculation methodology)
  • One 60 lb bag of concrete mix yields about 0.45 cubic feet. (Source: BoringToolsKit calculation methodology)
  • Always add about 10% waste for spillage and uneven hole bottoms. (Source: BoringToolsKit calculation methodology)
How sonotube concrete volume is calculated
12 in x 4 ft tube: 3.14 cu ft, 8 bags of 60 lb mix.
Volume pipeline for four 12-inch sonotube footings to bag counts
Four 12-inch tubes at 48 inches need 31 sixty-pound bags.
Transparent methodology

How this calculator works

Formula

Volume per tube (cu ft) = pi x (diameter/2/12)^2 x height (ft); bags = total volume x 1.10 / yield per bag.

Worked example

A 12 in x 4 ft sonotube holds pi x 0.5 ft squared x 4 ft = 3.14 cubic feet. With 10% waste that is 3.45 cu ft, which is 8 bags of 60 lb mix or 6 bags of 80 lb mix (QUIKRETE yields 0.45 and 0.60 cubic feet per bag).

Sources

Frequently asked questions

What is a sonotube concrete calculator and how does it work?

A sonotube concrete calculator is a browser-based tool that estimates the volume of concrete needed for cylindrical Sonotube forms. You enter the tube diameter, depth, and number of tubes, and it instantly calculates the cubic yards or feet of concrete required, no signup or download needed.

Do I need to create an account or sign up to use the sonotube concrete calculator?

No. This is a completely no-signup, browser-based tool. You can use it immediately in your web browser with no registration, no email, and no personal data collected.

How accurate are the results from the sonotube concrete calculator?

The calculator provides estimates based on standard cylindrical volume formulas using your input dimensions. It's a helpful planning tool, but always confirm with your concrete supplier and account for waste or over-excavation when ordering actual materials.

How much concrete do I need for a sonotube?

It depends on the diameter and height: volume equals pi times the radius squared times the height. A 12 inch diameter tube 4 feet tall needs about 3.14 cubic feet, or about 3.45 cubic feet once you add the recommended 10% waste allowance (roughly 8 bags of 60 lb mix).

How much concrete for an 18 inch sonotube?

An 18 inch diameter tube 4 feet tall holds about 7.07 cubic feet; budget about 7.8 cubic feet with 10% waste, which is about 18 bags of 60 lb mix or 13 bags of 80 lb mix at QUIKRETE yields of 0.45 and 0.60 cubic feet per bag.

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Cite this tool

BoringToolsKit. “Sonotube Concrete Calculator.” boringtoolskit.com/sonotube-concrete-column/. Free to reference in articles, syllabi, and answer posts with a link.

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Worked example: four 12-inch footings, 48 inches deep

Inputs: diameter 12 in, height 48 in, 4 tubes, 10% waste. The formula converts diameter to radius in feet: 12 / 2 / 12 = 0.5 ft. One tube holds pi x 0.5^2 x 4 = 3.14 cu ft, so four tubes give 12.57 cu ft total.

Convert to yards: 12.57 / 27 = 0.47 cu yd. Adding 10% waste: 0.47 x 1.1 = 0.51 cu yd. Bag counts use yield per bag: 60 lb bags yield 0.45 cu ft, so 0.51 x 27 / 0.45 = 30.7, rounded up to 31 bags. The 80 lb yield of 0.6 cu ft gives 0.51 x 27 / 0.6 = 23.0, rounded to 24 bags. The rounding up matters: a partial bag cannot be poured, and running short mid-pour leaves a cold joint in a footing that should be monolithic.

What the estimate leaves out: footing pads, footings below frost, and real pours

The calculator models the tube itself, so anything wider than the tube is on you. Common practice sets a round footing pad at the base, often 16 to 24 inches across for a 12-inch column at 6 to 8 inches thick. A 20-inch pad at 8 inches adds about 1.2 cu ft per post, roughly 1.3 extra 80 lb bags per hole.

Frost depth drives height, not the calculator. In much of the northern US that means 42 to 48 inches of embedment even for a short deck post; a 48-inch tube in a 48-inch hole leaves nothing above grade, so plan height as below-grade depth plus exposed column. Also budget 5 to 10% waste as a floor: overhang from an uneven hole, spillage, and a slightly over-sized auger all consume it. A 10-inch auger in a 12-inch specified hole quietly adds 44% more cross-sectional volume than the nominal diameter implies.