How Much Concrete for a 16-Inch Column Footing?
A 16-inch diameter round column footing at 4 feet deep is used for larger structural supports and heavy-load columns. Here are the pre-calculated concrete amounts with 10% waste.
Bag size
You'll need
0.23 cubic yards
Cubic feet
6.14
80 lb bags
11
Weight
0.46 tons
How This Calculator Works
The standard formula for a concrete slab — and the same math this calculator uses for all pour shapes:
Slab / Footing Volume (cu ft) = Length × Width × Depth (all in feet) Round column Volume (cu ft) = π × (Diameter ÷ 2)² × Height Convert to cubic yards Cu yds = Volume (cu ft) ÷ 27 Apply waste Final cu yds = Cu yds × (1 + Waste% ÷ 100) Bag count Bags = ⌈ Final cu ft ÷ yield per bag ⌉
One cubic yard equals exactly 27 cubic feet. A standard 80 lb bag yields approximately 0.60 cubic feet of finished concrete; a 60 lb bag yields 0.45 cu ft; a 40 lb bag yields 0.30 cu ft. These are industry-standard values used by Quikrete and Sakrete.
Bag counts always round up because you can't purchase a fraction of a bag. Concrete weight is estimated at 150 lb per cubic foot — the standard for normal-weight concrete.
Common Project Sizes
Base quantities without waste factor. Add 10% for a typical residential pour.
| Slab Size (4" thick) | Cubic Yards | Cubic Feet | 80 lb Bags |
|---|---|---|---|
| 4 × 4 ft | 0.20 | 5.3 | 9 |
| 4 × 8 ft | 0.40 | 10.7 | 18 |
| 6 × 6 ft | 0.44 | 12.0 | 20 |
| 8 × 8 ft | 0.79 | 21.3 | 36 |
| 10 × 10 ft | 1.23 | 33.3 | 56 |
| 12 × 12 ft | 1.78 | 48.0 | 80 |
| 16 × 16 ft | 3.16 | 85.3 | 143 |
| 20 × 20 ft | 4.94 | 133.3 | 223 |
How to Use This Calculator
The calculator above is pre-filled with the dimensions for a 16″ dia. × 4 ft column. You can adjust any field — length, width, thickness, quantity, waste percentage, or bag size — and the results will update instantly.
Select Footing or Column mode at the top if your project shape differs. Switch units on any field by clicking the ft / in / m / cm buttons.
Use the Quantity field if you're pouring multiple identical shapes. The Waste % default of 10% is standard for residential slabs — increase to 15% for irregular forms or first-time pours.
Frequently Asked Questions
How many bags of concrete do I need for a 16-inch column footing?
A 16-inch diameter column footing at 4 ft deep requires approximately 11 bags of 80 lb concrete mix (with 10% waste). Switch to 60 lb bags and you'll need about 15, or 40 lb bags for about 22.
How many cubic yards of concrete for a 16-inch column?
A 16-inch diameter column at 4 ft deep needs 0.23 cubic yards of concrete (including 10% waste). The formula is: π × (diameter ÷ 2)² × height — then add 10% waste and divide by 27 to convert cubic feet to cubic yards.
How much extra concrete should I order?
Order 10% more than your calculated volume for most pours. Increase to 15% for larger slabs or if your forms are irregular. The 10% default in this calculator accounts for typical spillage, over-pour at edges, and uneven subgrades. Running short means a cold joint — always worse than having a small amount left over.
Should I use bags or order ready-mix concrete?
For pours under about 1 cubic yard, bags from a hardware store are practical. For larger pours, a ready-mix truck is far more economical and saves hours of mixing. The breakeven is typically around 0.5–1 cubic yard.
How many 80 lb bags of concrete are in a cubic yard?
You need approximately 45 bags of 80 lb concrete mix per cubic yard. An 80 lb bag yields about 0.60 cubic feet of finished concrete, and one cubic yard equals 27 cubic feet: 27 ÷ 0.60 = 45 bags exactly.
What does the waste percentage account for?
The waste factor covers spillage during pouring, over-pour at form edges, uneven subgrade that adds volume, and concrete left in the mixer or chute. For a clean slab on level ground, 10% is standard.
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