Calculate exact concrete volume in cubic yards, cubic feet, and premix bag counts (50lb, 60lb, 80lb) for round Sonotube form tubes and deck pier footings.
Select tube diameter, hole depth, and pier counts
Nominal internal cardboard tube diameter
Must extend below local frost line (e.g. 48" = 4 ft)
Total batch pier quantity
Prevents uplift and spreads soil bearing load
14.4 Cubic Feet • 2.4 cu ft per pier (6 total)
0.60 cu ft yield / bag
0.45 cu ft yield / bag
0.375 cu ft yield / bag
@ $6.50 / 80lb bag
Calculating circular cylinder volumes manually involves squared radii and fractional foot conversions ($V = \pi r^2 h$). Making a slight unit conversion slip leaves homeowners short on concrete while the clock is ticking on a hot summer pour.
Many builders assume an 80 lb bag yields 1 cubic foot of concrete. In reality, one 80 lb bag yields only 0.60 cu ft, a 60 lb bag yields 0.45 cu ft, and a 50 lb bag yields 0.375 cu ft. Believing the 1:1 myth causes a severe 40% concrete shortage on site.
Mixing 50+ bags of concrete by hand in a wheelbarrow leads to worker exhaustion, cold joints, and uneven strength. Our calculator alerts you when total volume exceeds 1 cubic yard (~45 bags of 80 lb), letting you know when a ready-mix truck is more cost-effective.
Code requires piers to extend below frost depth to prevent frost heave. Wider bell footings (BigFoot forms) spread building weight across weak soil, adding 1.5 to 2.5 cubic feet per pier. This tool accounts for flared footing volumes seamlessly.
Pick nominal internal tube diameter (e.g. 8", 10", 12", 16") based on architectural deck plans.
Enter hole depth in inches or feet. Ensure depth reaches below your local municipal frost line.
Specify total number of columns and toggle optional flared bell footing adapters.
Check cubic yards for truck orders alongside exact counts for 50lb, 60lb, or 80lb bags.
Pre-loaded with commercial cardboard column sizes for deck footings, light poles, and pole barns.
Calculates exact cubic yards and cubic feet of poured concrete per tube and for the entire footing batch.
Instantly translates required volume into 50-lb, 60-lb, and 80-lb commercial concrete bags with waste allowances.
Includes footing flare volume options to anchor piers firmly below local frost depth lines.
A Sonotube is a right circular cylinder. Its volume equals: Volume = pi x (Diameter / 2)² x Depth. When using inches for diameter and feet for depth: Volume (cu ft) = (pi x (Diameter_in / 24)² x Depth_ft). To convert cubic feet to cubic yards, divide by 27: Cubic Yards = Volume (cu ft) / 27.
A 10-inch diameter tube 4 feet deep has a volume of: pi x (5/12)² x 4 = 2.18 cubic feet. One 80 lb bag of concrete yields 0.60 cubic feet of wet mixed concrete. Therefore: 2.18 / 0.60 = 3.63 bags. With a standard 10% safety margin, you need four 80 lb bags per 4-foot pier.
Per linear foot of tube depth: 8-inch holds 0.35 cu ft (0.58 bags of 80lb); 10-inch holds 0.55 cu ft (0.91 bags); 12-inch holds 0.79 cu ft (1.31 bags); 16-inch holds 1.40 cu ft (2.33 bags); and 18-inch holds 1.77 cu ft (2.95 bags).
Building codes require piers and footings to extend at least 6 to 12 inches below the local frost line to prevent frost heave from lifting and fracturing the structure. Frost depth varies geographically from 12 inches in warm southern states to 48-60 inches in northern states and Canada.
When total concrete volume exceeds 1.0 to 1.5 cubic yards (equivalent to 45 to 65 bags of 80 lb concrete), ordering a ready-mix truck is significantly faster, easier, and yields more consistent structural compressive strength (3,000 to 4,000+ PSI) without manual mixing fatigue.
Deck boards, joists, screws, and ledger attachments.
Equal baluster spacing with IRC 4-inch sphere code rules.
Material weight in tons and cubic yards for aggregates.
Drainage trench volume, pipe displacement, and fabric.
