Last updated: 2026-06-01
Quick Answer
To calculate concrete for a round column or Sonotube pier: Volume (ft³) = π × radius² × height (ft), then divide by 27 for cubic yards. Add 5–10% for waste. This column calculator does the math instantly. Enter the tube diameter in inches, the pour height in feet, and the number of columns, and it returns cubic yards, 60/80 lb bag counts, and an optional cost estimate.
Inputs you'll need
- Column / tube diameter (inches)
- Pour height per column (feet)
- Number of columns
- Waste / overage % (optional, but recommended)
- Price per cubic yard or price per bag (optional)
Related tools: Concrete Calculator, Concrete Footing Calculator, and Post Hole Concrete Calculator.
How to use this column calculator
- Pick a standard tube size or enter a custom diameter (inches).
- Enter the pour height per column in feet (footing depth + any stem above grade).
- Add your column count and set waste/overage (we default to 8%).
- Optionally add a ready-mix price per yard or a price per bag for a cost estimate.
Need to roll quantities into a clean customer quote? Start with our Cubic Yard Calculator.
Presets match standard Sonotube/round form diameters. Always follow the engineered plan for size and depth.
Inside diameter of the tube/form.
Total pour height per column (footing depth + any stem above grade).
Typical: 5–10% (spillage, form bulge, uneven base).
Delivered ready-mix quote ($110–$200/yd is common).
80 lb runs $5–$10; 60 lb runs $4–$8.
Assumptions
- Each column is a cylinder: volume = π × radius² × height.
- Waste is applied as a flat percentage to the total volume.
- Bag yields: 60 lb ≈ 0.45 ft³, 80 lb ≈ 0.60 ft³.
- Cost is material only. It does not include forms, rebar, excavation, labor, or delivery/short-load fees.
Concrete Column Results
Total volume (yd³)
0.75
Total volume (ft³)
20.4
80-lb bags (approx)
34
60-lb bags (approx)
46
Detailed Breakdown
12,800+ estimates calculated this month
Note: For ready-mix delivery, many contractors round up to the next 0.25 yd³ and budget a short-load fee on small pours.
Quick reference: concrete per column (no waste)
| Tube diameter | Per foot (ft³) | 4 ft column (ft³) | 80-lb bags (4 ft) |
|---|---|---|---|
| 8" | 0.349 | 1.40 | 3 |
| 10" | 0.545 | 2.18 | 4 |
| 12" | 0.785 | 3.14 | 6 |
| 16" | 1.396 | 5.59 | 10 |
| 18" | 1.767 | 7.07 | 12 |
| 24" | 3.142 | 12.57 | 21 |
Concrete Column & Sonotube Guide
Standard tube sizes, volume per foot, frost-depth requirements, and ordering tips for round concrete piers.
How Much Concrete a Round Column Needs
A round column holds π × radius² × height of concrete. Convert the diameter to feet (inches ÷ 12), halve it for the radius, then multiply by the pour height in feet to get cubic feet. Divide by 27 for cubic yards.
- 8" tube, 4 ft: ≈ 1.40 ft³ (about 3 bags of 80 lb)
- 10" tube, 4 ft: ≈ 2.18 ft³ (about 4 bags of 80 lb)
- 12" tube, 4 ft: ≈ 3.14 ft³ (about 6 bags of 80 lb)
- 16" tube, 4 ft: ≈ 5.59 ft³ (about 10 bags of 80 lb)
An 80 lb bag yields about 0.60 ft³ and a 60 lb bag about 0.45 ft³. Once you pass roughly 1 cubic yard total (about 45 bags of 80 lb), ready-mix delivery is usually cheaper and far less back-breaking than mixing bags.
Key Takeaways
- Volume = π × radius² × height
- 80 lb bag ≈ 0.60 ft³, 60 lb bag ≈ 0.45 ft³
- Past ~1 yd³, switch from bags to ready-mix
Sizing Sonotube Piers and Columns
Round forms (Sonotube and similar) come in standard diameters: 8", 10", 12", 16", 18", and 24". The size you need depends on the load and the soil, not just what fits the post.
- 8"–10": light decks, fences, and small porch piers
- 12": the workhorse for residential deck and porch footings
- 16"–18": heavy posts, beam columns, and poor soils
- 24": structural columns carrying large point loads
Footings must extend below the frost line, which ranges from about 12" in the South to 48"+ in the northern states. Coming up short on depth fails inspection and invites frost heave that can lift the whole structure.
Key Takeaways
- Standard tube sizes: 8", 10", 12", 16", 18", 24"
- 12" is the common residential deck pier
- Pour depth must clear the local frost line
Ordering and Pouring Tips That Save Money
Order 5–10% extra so you never run short mid-pour. A column you stop halfway leaves a cold joint, and a second delivery for one missing yard costs a short-load fee that can run $50–$150.
- Brace and plumb every tube before the truck shows up. Concrete is heavy and tubes bulge.
- Add rebar or a column cage per your plan. This calculator covers concrete only.
- For multiple piers, total all columns first so you can order one delivery instead of several bag runs.
- Round ready-mix orders up to the next 0.25 yd³ to match how plants batch.
I have been on pours where a 0.3 yard shortage stopped the whole crew. A few extra bags on the truck is cheaper than the downtime.
Key Takeaways
- Add 5–10% waste to avoid a cold joint
- Short-load fees run $50–$150 per trip
- Total all columns into one order
Column volume examples (5 test cases)
Use these to sanity-check your numbers. (Volumes shown are before waste unless noted.)
| Case | Inputs | Expected |
|---|---|---|
| 1 | 12" dia, 4 ft, 1 column, 0% waste | π × 0.5² × 4 = 3.14 ft³ (0.116 yd³) |
| 2 | 8" dia, 4 ft, 1 column, 0% waste | π × 0.333² × 4 = 1.40 ft³ (3 bags of 80 lb) |
| 3 | 16" dia, 5 ft, 1 column, 0% waste | π × 0.667² × 5 = 6.98 ft³ (0.259 yd³) |
| 4 | 12" dia, 4 ft, 6 columns, 0% waste | 3.14 × 6 = 18.85 ft³ (0.70 yd³) |
| 5 | 12" dia, 4 ft, 6 columns, 8% waste | 18.85 × 1.08 = 20.36 ft³ (0.75 yd³) |
Common tube sizes and concrete per foot
Round forms are sold in these standard diameters. Pick the size from your engineered plan, not just what clears the post.
| Tube diameter | ft³ per foot | Typical use |
|---|---|---|
| 8" | 0.349 | Light deck, fence, small porch piers |
| 10" | 0.545 | Deck post piers |
| 12" | 0.785 | Common residential deck/porch pier |
| 16" | 1.396 | Heavy posts, beam columns, poor soil |
| 18" | 1.767 | Structural columns |
| 24" | 3.142 | Heavy structural columns / large point loads |
Volume per foot = π × (diameter ÷ 24)². Confirm size and depth with your local building department.
Common mistakes (avoid these)
- Mixing units: diameter is inches, height is feet. Convert before you multiply.
- Using the radius where the formula wants diameter (or the reverse).
- Forgetting waste and stopping mid-column, which leaves a weak cold joint.
- Ordering bags for a job that is past a yard, when ready-mix would be cheaper.
Pouring footings under those columns too? Run the numbers through the Concrete Footing Calculator.
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How to Use This Calculator
Pick the tube size
Choose a standard Sonotube diameter (8"–24") or enter a custom diameter in inches.
Enter the pour height
Add the total height per column in feet, including footing depth below grade plus any stem above grade.
Set the column count and waste
Enter how many columns you are pouring and add 5–10% waste for spillage and form bulge.
Optional: estimate cost
Add your ready-mix price per yard or your price per bag to see a material cost estimate.
Concrete Column Formulas
Radius (ft) = Diameter (in) ÷ 24
Volume per column (ft³) = π × Radius² × Height (ft)
Total Volume (ft³) = Volume per column × Number of columns
Volume w/ Waste = Total Volume × (1 + Waste%/100)
Volume (yd³) = Volume (ft³) ÷ 27
80-lb bags = Volume w/ Waste ÷ 0.60
60-lb bags = Volume w/ Waste ÷ 0.45Where:
- Diameter ÷ 24
- = Converts tube diameter (inches) to radius in feet
- Waste%
- = Overage for spillage, form bulge, and uneven base (5–10% typical)
- 0.60 / 0.45
- = Cubic-foot yield of an 80 lb and a 60 lb bag of concrete mix
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Frequently Asked Questions
How do you calculate concrete for a round column?
How much concrete is in a 12-inch Sonotube?
How many bags of concrete do I need per column?
When should I use ready-mix instead of bags for columns?
How deep do concrete columns and piers need to go?
Does this calculator include rebar or labor?
How much waste should I add for column pours?
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