Enter your tube diameter, pour depth, and number of tubes to instantly calculate concrete volume in cubic yards, bag counts per tube and total, and material cost estimate.
Free to use
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No sign-up required
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π × r² × h formula — exact cylinder volume
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Imperial & metric supported
✓ Per-tube & total bag counts✓ Cost estimator included✓ Works on any device✓ Last verified May 2026
Reviewed by the AllConcreteCalculator.com editorial team — cylinder volume formula verified against standard geometric principles and ACI 318 footing requirements, May 2026.
Enter Your Sonotube Dimensions
Sonotube inner diameter. Common sizes: 6, 8, 10, 12, 14, 16 in.
Please enter a valid diameter greater than 0.
Depth of concrete fill — typically the full tube length below grade.Please enter a valid depth greater than 0.
Total number of identical tube footings on this job.
10% is standard. Use 15% if tubes vary in length or soil is loose.
$
Leave blank to skip cost estimate. US average: $100–$150/yd³ for ready-mix.
Results appear instantly. No sign-up required.
Your Sonotube Concrete Estimate
Total Concrete Volume — All Tubes (with waste)
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Cubic Yards (yd³)
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Cubic Feet (ft³)
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Cubic Meters (m³)
Volume per Single Tube (no waste)
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yd³ / Tube
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ft³ / Tube
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m³ / Tube
Total Bags Required — All Tubes (includes waste)
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40 lb bags
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60 lb bags
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80 lb bags
—Diameter
—Depth
—Tubes
—Waste Factor
Estimated Material Cost
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Concrete material cost only. Add excavation ($2–$6/linear ft), form tubes ($3–$12 each), anchor hardware, and labor for a full project budget. Use our Full Project Estimator for a complete breakdown.
Step 1: Convert diameter and depth to feet
Step 2: Radius (ft) = diameter (ft) ÷ 2
Step 3: Volume per tube (ft³) = π × radius² × depth (ft)
Step 4: Total volume (ft³) = volume per tube × number of tubes
Step 5: Cubic Yards = total ft³ ÷ 27
Step 6: Final Volume = total volume × (1 + waste% ÷ 100)
Step 7: Bags = CEIL(final ft³ ÷ bag yield) — never round down
Measure the tube's inside diameter.
Use the labeled size on the sonotube packaging — sizes are nominal inner diameters. A "10-inch sonotube" has a 10-inch inside diameter; the cardboard wall adds about ¼ inch on each side but does not affect your concrete volume. If you're sizing tubes for a building permit, the required diameter is typically specified in the footing schedule on your plans.
Determine your pour depth.
This is the length of tube that will be filled with concrete — typically the distance from the bottom of the hole to the top of your finished pier. In most cases this equals the tube length, minus any portion left empty above grade if you're only filling to a specific height. When in doubt, fill the entire tube for maximum strength.
Enter the number of identical tubes.
All tubes in the calculator must share the same diameter and depth. If your job uses different tube sizes (e.g., 10-inch corner piers and 8-inch interior piers), run two separate calculations and add the bag totals together.
Use your results to order materials.
For small tube counts, compare the bag totals to the minimum ready-mix order for your area (usually 1 cubic yard). If bags are cheaper and more practical, buy them. For large jobs, share the cubic yard total with your ready-mix supplier. Always confirm final quantities before ordering.
⚠ Pro Tip: Sonotubes hold their form during a pour only when backfilled or braced — an unfilled hole will let the tube shift or float when you add concrete. Backfill and tamp soil around the tube before pouring, or brace it with temporary stakes. A tube that moves mid-pour means a misaligned post anchor and an expensive redo.
Sonotube Concrete Volume Formula
A sonotube is a cylinder. The exact volume formula is π × r² × h, where r is the radius (half the diameter) and h is the pour depth. Everything must be converted to the same unit (feet for cubic feet, then ÷27 for cubic yards) before applying the formula.
Step
Formula
Example (10 in dia. × 48 in deep)
1. Convert diameter to feet
inches ÷ 12
10 ÷ 12 = 0.8333 ft
2. Find radius
diameter ÷ 2
0.8333 ÷ 2 = 0.4167 ft
3. Convert depth to feet
inches ÷ 12
48 ÷ 12 = 4.000 ft
4. Volume per tube (ft³)
π × r² × depth
3.14159 × 0.4167² × 4 = 2.182 ft³
5. Convert to cubic yards
ft³ ÷ 27
2.182 ÷ 27 = 0.0808 yd³
6. Add waste factor (10%)
Volume × 1.10
0.0808 × 1.10 = 0.0889 yd³
7. Bags (80 lb, 0.60 ft³ yield)
CEIL(final ft³ ÷ 0.60)
CEIL(2.40 ÷ 0.60) = 4 bags
Sonotube Concrete Volume Reference Table
Concrete volumes per tube — no waste factor applied. Add 10% for real-world ordering. Depths in inches.
Diameter
Depth
ft³ / Tube
yd³ / Tube
60 lb Bags
80 lb Bags
6 in
24 in
0.393
0.015
1
1
6 in
48 in
0.785
0.029
2
2
8 in
36 in
1.047
0.039
3
2
8 in
48 in
1.396
0.052
4
3
10 in
36 in
1.636
0.061
4
3
10 in
48 in
2.182
0.081
5
4
12 in
36 in
2.356
0.087
6
4
12 in
48 in
3.142
0.116
7
6
12 in
60 in
3.927
0.145
9
7
14 in
48 in
4.276
0.158
10
8
16 in
48 in
5.585
0.207
13
10
18 in
48 in
7.069
0.262
16
12
24 in
48 in
12.566
0.465
28
21
Bag counts are CEIL of exact volume ÷ bag yield. No waste factor applied — add 10% when ordering.
What Sonotube Diameter Do I Need?
Diameter is the most structurally significant variable in footing design. Bigger diameter means a larger bearing area, which lets the footing support more load without punching into the soil. The table below gives common application guidance, but your local building code — and an engineer for anything structural — takes precedence.
Sonotube diameter selection guide by application. Depths must meet local frost requirements.
Application
Typical Diameter
Typical Depth
Notes
Fence post in frost-free zone
6 inches
24–30 in
Minimal load, decorative only
Fence post in frost zone
8 inches
Below frost line
Prevents heaving
Residential deck pier (light load)
8–10 inches
Below frost + 12 in
Tributary area ≤ 20–30 ft²
Residential deck pier (standard)
10–12 inches
Below frost + 12 in
Most common deck application
Residential deck pier (corner/beam)
12–14 inches
Below frost + 12 in
Higher tributary load
Structural column / pergola post
14–16 inches
36–60 in or per engineer
Engineer stamp often required
Commercial sign base
18–24 inches
Per wind load calc
Always engineered
Light pole / traffic signal base
24–36 inches
Per engineering specs
Engineered — do not estimate
The cheapest upgrade on any footing job is going one size up on diameter. The material cost difference between a 10-inch and 12-inch tube is minimal — roughly one extra 80 lb bag per tube. The bearing area difference is 44% more. If you're borderline on load, size up. Undersized footings fail quietly; by the time you notice, you're dealing with a settled structure.
Common Mistakes When Estimating Sonotube Concrete
⚠️
Using the outside tube diameter instead of the inside.
The concrete fills the inside of the tube. Sonotube diameters printed on packaging are nominal inside measurements, but if you're measuring a tube yourself, measure inside edge to inside edge. Using the outer diameter — which adds the cardboard wall — will overstate your concrete volume by several percent on smaller tubes.
📐
Forgetting that holes are never perfectly cylindrical.
A power auger cuts a slightly tapered hole, and loose or wet soil crumbles into the bottom. Your actual concrete pour will fill some of that extra void. Rounding up on depth and adding a 10–15% waste factor is not being conservative — it's being realistic about how holes actually behave in the field.
📦
Ordering one bag per tube without calculating actual volume.
This is the most common mistake on small deck jobs. A 12-inch tube at 48 inches deep needs roughly 6–7 bags of 60 lb concrete — not one. Eyeballing bag counts without calculating first leads to multiple hardware store runs mid-job. Run the numbers before you start digging.
🌡️
Not accounting for cold weather curing time before loading.
Concrete cures through a chemical hydration reaction that slows dramatically in cold temperatures. Below 40°F, hydration nearly stops. If you set anchor bolts and immediately frame a deck in below-freezing conditions, you're loading green concrete. Protect fresh piers with insulating blankets and wait a minimum of 7 days — longer in sustained cold.
🔩
Setting post anchors too late or without a template.
Anchor bolts and post brackets must be set in wet concrete while it's still workable — typically within 20–30 minutes of a pour. Trying to drill and epoxy anchors into cured concrete is a salvage operation, not a plan. Before you mix a single bag, have all hardware on-site, measured, and templated to the correct spacing and orientation.
Frequently Asked Questions
Use the cylinder formula: Volume = π × (diameter/2)² × depth. Convert all measurements to feet first. For example, a 10-inch diameter tube at 48 inches deep: radius = 0.4167 ft, volume = 3.14159 × 0.4167² × 4 = 2.18 ft³ per tube. Divide by 27 for cubic yards. Always add at least 10% waste. This calculator does all of that instantly and also provides per-tube bag counts.
A 10-inch diameter sonotube at 4 feet deep requires approximately 2.18 ft³ of concrete before waste. With 10% waste, you need about 2.40 ft³. That works out to 4 bags of 80 lb concrete (0.60 ft³ yield each) or 6 bags of 60 lb (0.45 ft³ yield each). Always round up — never down — since you cannot add concrete once it begins to cure.
A sonotube is a round cardboard or fiber tube form used to cast cylindrical concrete piers and column footings. The name originated from Sonoco Products but is now used generically for all concrete tube forms. They come in standard diameters from 6 inches to 48 inches or larger, and are used for deck piers, fence posts, sign bases, and structural column footings. After the concrete cures, the tube is stripped away above grade; the buried portion can be left in place.
Footing depth depends on your local frost depth plus a minimum bearing depth. In most of the northern US, frost depth ranges from 36 to 60 inches — you must extend the footing at least 12 inches below the frost line. Local building codes are the final authority. In frost-free climates (Deep South, Southwest), 24 inches is a common minimum for deck piers. Always verify with your local building department before digging.
For fewer than 5–6 small tubes, bagged concrete is practical and cost-effective. A typical 10-inch tube at 4 feet deep needs only about 4 bags of 80 lb concrete. For large projects (10 or more tubes, or large-diameter tubes), ready-mix becomes more efficient. The breakeven point is roughly 1 cubic yard total — once you exceed that, ready-mix pricing is usually competitive with bags and far less labor-intensive.
Typical residential decks use 10-inch or 12-inch sonotubes for interior piers and 12-inch to 14-inch for corners or heavily loaded beam points. The correct diameter depends on the tributary load area each pier supports, the allowable soil bearing capacity, and your local building code. Most jurisdictions require an engineered footing design for decks over a certain height or load — check with your building department before assuming a size.
Yes for the portion above grade — the exposed cardboard will absorb moisture, swell, and degrade quickly, and it looks poor. Peel the tube off above grade after the concrete reaches initial set (typically 24–48 hours). For buried sections below grade, the tube can be left in place since it will decompose underground without affecting structural integrity. Many contractors strip the entire tube regardless; both approaches are acceptable below grade.
Concrete reaches roughly 70% of its design strength at 7 days and near full 28-day strength after a month. For residential deck piers, most contractors wait at least 3–7 days before loading. In cold weather (below 50°F), curing slows significantly and you should wait longer. Never load fresh piers in freezing conditions — protect with insulating blankets and wait for a sustained warm period before framing on top.
Technically yes, but it is generally not recommended for sonotube work. Fast-setting mixes (Quikrete Fast-Setting, etc.) begin hardening within 20–40 minutes, leaving little time to set anchor bolts, adjust post brackets, or verify alignment before the concrete locks up. Standard 4,000 PSI mix gives you 45–60 minutes of working time, which is far more practical when you need to precisely position hardware. Reserve fast-setting mix for post holes where you can pour dry mix into the hole and flood with water.
A post hole is the excavated hole in the ground. A sonotube is the round tube form placed inside that hole to shape the concrete pour into a clean cylinder. You dig the hole (typically with a power auger), drop in the sonotube cut to the right length, fill with concrete, set anchor hardware, and strip the above-grade portion once cured. Without a tube, caving soil contaminates the wet concrete and you end up with an irregular, weaker pier.
