Sonotube & Tube Form Concrete Calculator
By Vinod Kondeti · Updated
Tube forms are sold by inside diameter (8, 10, 12 in and up), and deck piers usually need several of them. Set the number of tubes and the calculator gives the total, so you can buy all the bags in one trip.
How do I measure for a sonotube pour?
- Height is the full concrete height, from the bottom of the hole to the top of the tube.
- If the hole below the tube is wider (a bell or footing pad), add it separately as a slab.
- Common sizes per 4 ft of tube: 8 in ≈ 1.40 ft³, 10 in ≈ 2.18 ft³, 12 in ≈ 3.14 ft³.
Sonotube concrete questions
How many 80 lb bags for a 10 in × 4 ft tube?
2.18 ft³ ÷ 0.60 = 3.6, so 4 bags per tube.
How many bags for 6 tubes?
Calculate the total first and then round up: 6 × 2.18 = 13.1 ft³, which is 22 bags of 80 lb (not 6 × 4 = 24).
Bag yields: 0.30 / 0.45 / 0.60 ft³ for 40 / 60 / 80 lb standard concrete mix (manufacturer data sheets). The concrete guide has the formulas and worked examples.
Sources
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