Concrete Column Calculator

Calculating the concrete volume needed for a round column (cylinder) uses the formula V = π × r² × h.

1. Measure Diameter: Measure the internal diameter of the column form (e.g., Sonotube) or the desired diameter of the finished column.
2. Measure Height: Measure the height of the column form or the required height of the concrete column.
3. Convert Units & Find Radius: Ensure consistent units. The calculator takes diameter in inches/cm and height in feet/meters. It internally converts the diameter to feet/meters and calculates the radius (r = diameter / 2).
4. Apply Formula: Calculate the volume using the formula:
   Volume = π × (Radius)² × Height
5. Calculate Total Volume: Multiply the volume of a single column by the total number of identical columns.
6. Convert to Standard Units: The calculator converts the final volume to cubic feet, cubic yards, and cubic meters for convenience.

• Units: Select the measurement system you are using. This determines whether diameter is expected in inches or cm, and height in feet or meters.
• Number of Columns: Enter the total count of identical columns you need to pour.
• Column Diameter: The internal diameter of the round column form.
• Column Height: The height of the concrete required within the form.

Similar to slab calculations, you can estimate the number of pre-mix concrete bags needed for columns:

1. Calculate Total Volume Needed (in Cubic Feet): Use the calculator to find the total volume for all columns in cubic feet.
2. Find Bag Yield: Check the concrete bag packaging for its yield in cubic feet (e.g., 0.45 ft³ for 60lb, 0.60 ft³ for 80lb).
3. Divide Total Volume by Bag Yield:
   Number of Bags = Total Volume (ft³) / Yield per Bag (ft³)
4. Round Up: Always round up to the nearest whole bag.

The calculator provides estimates for common 60lb and 80lb bags.

• Waste Factor: The calculator provides the theoretical volume. Always add 5-10% extra when ordering ready-mix or buying bags to account for waste, spills, and potential variations.
• Form Stability: Ensure column forms are properly braced and secured before pouring concrete. The weight of wet concrete exerts significant pressure.
• Consolidation: Concrete in columns needs proper consolidation (usually with a concrete vibrator or thorough rodding) to remove air voids and ensure strength, especially around reinforcing steel.
• Reinforcement: This calculator doesn't account for the volume of rebar cages within the column. For very heavily reinforced columns, you might slightly reduce the calculated volume, but the standard 5-10% waste factor usually covers this small displacement.
• Top Finish: Consider if you need extra concrete for forming a specific top shape or embedding hardware (like post bases).