Concrete Column Calculator
Estimate how much concrete you need for a round column, pier or sonotube — in cubic yards and cubic meters — with an optional waste allowance for spillage and over-pour.
Result
| Volume | |
| Volume (metric) | |
| Order quantity (with waste) |
Units & conversions used
Imperial inputs are inches (diameter) and feet (height); results are shown in cubic feet, cubic yards (1 yd³ = 27 ft³) and cubic meters (1 ft³ = 0.02832 m³). Metric inputs are converted first: 1 m = 3.28084 ft, 1 cm = 0.3937 in.
Formula & source
V(ft³) = π × r² × height(ft)
V(yd³) = V(ft³) ÷ 27
Source: basic cylinder geometry — no external authority needed, it is the standard formula for the volume of a cylinder. The 5–10% waste allowance is standard ready-mix ordering practice (covers spillage and slight over-pour); it is an industry rule of thumb, not a code requirement. Column structural design (diameter, reinforcement, ties/spiral) is governed by ACI 318 and local codes — this calculator does not cover that.
Worked example (you can verify by hand)
Input: 12 in diameter × 4 ft tall, 7% waste.
- Radius in feet: 12 ÷ 2 ÷ 12 = 0.5 ft
- Volume: π × 0.5² × 4 = π = 3.1416 ft³
- Cubic yards: 3.1416 ÷ 27 = 0.1164 yd³
- With 7% waste: 0.1164 × 1.07 = 0.1245 yd³
Expected output: 3.1416 ft³ = 0.12 yd³ (0.12 yd³ with waste, 0.089 m³ / 0.095 m³ with waste).
Limitations — what this cannot do
- This estimates volume only. It does not design the column: diameter, concrete strength, vertical reinforcement and ties/spiral are governed by ACI 318 and local building codes; consult a structural engineer for load-bearing columns.
- Assumes a straight cylinder of constant diameter. Bell-bottom footings, tapered or irregular forms are only approximate — break them into sections or add extra waste.
- Ready-mix suppliers have minimum load charges; small orders may cost more per yard.
FAQ
How much concrete do I need for a 12-inch diameter, 4-foot tall sonotube?
π × (0.5 ft)² × 4 ft = 3.1416 ft³ ÷ 27 = 0.12 yd³. Add 7% waste for about 0.12 yd³ to order — a single 80 lb bag of ready-mix yields roughly 0.6 ft³, so you would need about 6 bags.
What is the formula for the volume of a concrete cylinder?
V = π × r² × h, where r and h use the same units. For a 12 in diameter, 4 ft tall column: r = 0.5 ft, so V = π × 0.25 × 4 = 3.1416 ft³.
Should I add extra for waste?
Yes — 5–10% is standard practice. Tubes can bow slightly, forms leak a little, and some concrete sticks to the chute. It is cheaper than a short load.
Can this size my deck pier columns structurally?
No. This calculator only estimates concrete volume. Column diameter, depth below frost line and reinforcement must follow your local building code and the deck plan — ask the building department or an engineer.