MaterialSum

Sonotube Concrete Calculator

Deck posts, mailboxes, footings — enter tube diameter, depth, and quantity to get the concrete you need.

Tube Dimensions
in
ft
Material
Optional Cost
Enter your measurements above to see results.

How to use the Sonotube Concrete Calculator

  1. Enter the tube diameter (8, 10, 12 in are common Sonotube sizes).
  2. Enter the pour height — for decks, that is often the below-grade length plus any above-ground column.
  3. Set the number of tubes and a small (5%) waste allowance.

Formula & methodology

Volume per tube = π × (diameter ÷ 2)² × height. Bags = total volume × (1 + waste) ÷ bag yield (80 lb ≈ 0.60 ft³).

Example

Six 12 in tubes, 4 ft deep each: π × 0.25 ft² × 4 ft ≈ 0.116 yd³ per tube — 0.70 yd³ total, about 32 bags of 80 lb mix.

Related calculators

Concrete CalculatorEnter your project dimensions to find out how much concrete you need — in cubic yards, cubic meters, or bags of Quikrete-style mix.Concrete Cost CalculatorEnter your slab dimensions and local pricing to see what the pour will actually cost — including the delivery fee that surprises everyone.Gravel CalculatorMeasure your area, choose a depth, and instantly see how much gravel to order in cubic yards, tons, or bags.

FAQ

How many bags of concrete per Sonotube?

A 12 in × 4 ft tube takes about 5.3 bags of 80 lb mix. An 8 in × 4 ft tube takes about 2.4. This calculator totals any quantity of tubes.

Should the tube be filled to the top?

Fill to your design height — for decks, many builders pour to just above grade and use an adjustable post anchor. Follow your plan for structural sizing.

Do I need rebar in Sonotubes?

Often yes for decks — local codes commonly require rebar or anchor bolts. Rebar displaces a negligible amount of concrete; ignore it in the volume math.

Can I use fast-setting mix in tubes?

Yes, and it is popular for fences — it sets in 20–40 minutes. Yield per bag is similar to regular mix, so the bag counts here still apply.

Note: Volume estimate only. Post footing diameter and depth for structures must follow local code or an engineer's specification.