Sonotube Bag Calculator — Concrete Bags Per Tube
Convert sonotube concrete volume to 60 and 80-pound bag counts. Includes ready-mix ordering thresholds so you know when to switch from bags to a truck.
Enter Dimensions
Depth below grade to bottom of footing
Results
Bags per Tube
5bags
Total Bags
20bags
Volume per Tube
2.18cu ft
Concrete volume for one tube
Total Volume
0.323cu yd
All tubes combined
Editorial Standards
Each calculator is reviewed for formula accuracy, unit consistency, and alignment with current U.S. building practices before publication. We verify outputs against published engineering references and real-world project data. Learn more about our methodology.
For 1-6 Sonotube footings, bag mixing is the default — you can buy bags at any home center and pour as your schedule allows. Above 6 footings (typically 1+ cubic yard total), ready-mix delivery wins on both cost and labor time.
This calculator converts Sonotube concrete volume to 60 lb and 80 lb bag counts using standard yields (0.45 and 0.60 cu ft per bag respectively). It also flags when you've crossed the ready-mix threshold.
How to Calculate Concrete Bags for Sonotubes
Bags (80 lb) = ⌈Total Concrete (cu ft) ÷ 0.60⌉. Bags (60 lb) = ⌈Total ÷ 0.45⌉. Multiply by waste factor first (typically 5%).
Sonotube Bag Count Quick Reference
(Per single footing, 80 lb bags, no waste added)
- 8″ × 4 ft: 1.40 cu ft = 3 bags
- 10″ × 4 ft: 2.18 cu ft = 4 bags
- 12″ × 4 ft: 3.14 cu ft = 6 bags
- 10″ × 5 ft (deep frost): 2.73 cu ft = 5 bags
- 12″ × 5 ft: 3.93 cu ft = 7 bags
- 16″ × 6 ft (heavy pier): 8.38 cu ft = 14 bags — consider ready-mix.
Ready-Mix vs Bag Cost Breakeven
Ready-mix at $150-220/yd × short-load fee $50-150 = $200-370 for 1 yd. 80 lb bags at $5/bag × 45 bags/yd = $225 plus 6 hours mixing labor. Above ~1.5 yd, ready-mix wins on both metrics.
Frequently Asked Questions
How many bags of concrete for a 10 inch Sonotube 4 ft deep?
Volume = π × (5/12)² × 4 = 2.18 cu ft. At 0.60 cu ft per 80 lb bag = 4 bags. At 0.45 cu ft per 60 lb bag = 5 bags. Add 5-10% waste = 4-5 bags total.
60 lb or 80 lb bags?
80 lb bags are more economical per cubic foot ($5-6 vs $4-5 for 60 lb). 60 lb bags are easier on your back during repeated lifting. For projects with 10+ footings, 80 lb saves time and money; for 1-3 footings, 60 lb is acceptable.
When does ready-mix beat bag mix?
Above 1 cubic yard (27 cu ft) total project. A short-load delivery typically costs $200-350 ($50-150 short-load fee + $150-200 per yard). At 80 lb bags @ $5 each, 1 yd = 45 bags = $225 plus 4-6 hours of mixing labor.
How long does it take to mix bag concrete?
10-15 minutes per 80 lb bag in a wheelbarrow with a hoe, or 5 minutes per bag in a small electric mixer. A 6-footing deck project = 24-30 bags = 2-3 hours of mixing time alone.
Should I use fast-set or standard concrete in Sonotubes?
Fast-set (Quikrete fast-set or similar) cures the post in 20-40 minutes — handy for time-constrained installs. Standard 4000 psi takes 24 hours to set but reaches higher ultimate strength. Most deck pros use standard for cost.
Looking for the general calculator?
Calculate concrete volume and bags needed to fill Sonotube forms for deck posts and piers. Supports 6, 8, 10, and 12-inch diameter tubes at any footing depth.
Open the Sonotube Calculator: Bags Per Footing →