Concrete Cylinder Calculator
Accurately estimate the concrete required for round columns, posts, and cylindrical structures. This calculator supports multiple identical cylinders, includes a 10% waste factor, and provides bag counts for both 60lb and 80lb mixes.
Internal diameter of the cylinder form
Total height of the cylinder or column
Optional - for cost estimation
V = π × r² × h
Where:
r = Diameter ÷ 2
Steps:
1. Convert diameter to feet (÷ 12)
2. r = diameter / 2
3. V = π × r² × height (ft)
4. Cubic yards = V ÷ 27
5. Add 10% for waste
Radius = 6″ = 0.5′
Area = π × 0.5² = 0.785 sq ft
Volume = 0.785 × 10 = 7.85 cu ft
Cubic Yards = 7.85 ÷ 27 = 0.29
With 10% waste = 0.32 cu yds
80lb bags needed = 7.85 ÷ 0.6 = 14 bags
How do I calculate concrete for round columns?
Multiply the cross-sectional area (π × radius²) by the height. For example, a 12-inch diameter column that is 10 feet tall: radius = 6 inches = 0.5 feet, area = π × 0.5² = 0.785 sq ft, volume = 0.785 × 10 = 7.85 cubic feet = 0.29 cubic yards.
How many bags of concrete do I need for a cylinder?
One 80lb bag of concrete mix yields approximately 0.6 cubic feet. To find bags needed, divide your total volume in cubic feet by 0.6 and round up. For a 12" diameter × 4ft tall column: 3.14 cu ft ÷ 0.6 = 5.2 → 6 bags of 80lb mix.
What is the standard concrete cylinder size for testing?
Standard test cylinders are 6 inches in diameter by 12 inches tall (6"x12"), containing 0.196 cubic feet of concrete. Some applications use 4"x8" cylinders. These cylinders are cast from fresh concrete and tested at 7, 14, and 28 days to verify compressive strength.
Should I use a sonotube for concrete cylinders?
Yes, Sonotube (or any fiber form tube) is the standard method for forming round concrete columns and piers. They come in diameters from 6" to 48" and are designed to be disposable after the concrete cures. Always brace and plumb the tube before pouring.
🔗 Related Calculators
📐 Formula
V = π × r² × h
Where:
r = Diameter ÷ 2
Steps:
1. Convert diameter to feet (÷ 12)
2. r = diameter / 2
3. V = π × r² × height (ft)
4. Cubic yards = V ÷ 27
5. Add 10% for waste
📝 Example Calculation
Radius = 6″ = 0.5′
Area = π × 0.5² = 0.785 sq ft
Volume = 0.785 × 10 = 7.85 cu ft
Cubic Yards = 7.85 ÷ 27 = 0.29
With 10% waste = 0.32 cu yds
80lb bags needed = 7.85 ÷ 0.6 = 14 bags