How Much Concrete for a 16 Foot Round Slab?
How much concrete for a 16 foot round slab: about 2.48 cubic yards at 4 inches thick. A circle 16 feet across has a radius of 8 feet and an area of about 201.1 square feet (π × 8²).
Concrete calculator →The circle math
- Radius: 16 ÷ 2 = 8 ft.
- Area: 3.1416 × 8 × 8 = 201.1 sq ft.
- Volume at 4 in: 201.1 × 0.333 = 67.0 cu ft.
- Yards: ÷ 27 = 2.48 yd³.
A round slab takes about 21 percent less concrete than a square of the same width (16x16 would need 3.16 yards at 4 inches).
Related: How Much Concrete for a 24 Foot Round Slab?
By thickness
| Thickness | Cubic feet | Cubic yards | Yards +10% | 80 lb bags | 60 lb bags |
|---|---|---|---|---|---|
| 4 in | 67.0 | 2.48 | 2.73 | 112 | 149 |
| 5 in | 83.8 | 3.10 | 3.41 | 140 | 187 |
| 6 in | 100.5 | 3.72 | 4.10 | 168 | 224 |
Forming a circle
Mark the circle with a stake and a string the length of the radius. Flexible form material such as hardboard strips or plastic forms bends to the curve; stake it closely, since curves push outward when the concrete goes in.
Related: How Much Concrete for a 24 Foot Round Slab?
Common uses and thickness
Fire pit patios, gazebo floors and tank pads are the usual round slabs. For people and furniture, 4 inches on compacted gravel is standard. Anything heavy needs more thickness and possibly reinforcement; check the manufacturer’s requirements for tanks or bins.
Joints in a round slab
Cut control joints like pie slices from the center outward, with an optional ring joint for larger circles, so each panel stays a manageable size.
Questions people ask
How many yards of concrete for a 16 ft round slab?
About 2.48 cubic yards at 4 inches.
How many square feet is a 16 ft circle?
About 201.1 square feet.
How many 80 lb bags for a 16 ft round slab?
About 112 bags at 4 inches thick.
How do I find the area of a circle?
Multiply 3.1416 by the radius squared. The radius is half the diameter.
How much does a cubic yard of concrete weigh?
Roughly 4,000 pounds, or about 2 tons, for normal-weight concrete.
Related guides
- How Much Area Does a Yard of Concrete Cover?
- How Many Bags of Concrete in a Yard? 40, 60, 80 lb
- Gravel Base Under a Concrete Slab: Depth and Tons
- How Many Yards in a Concrete Truck? Mixer Sizes
- Concrete Short Load Fee: What It Is and How to Cut It
- 60 lb vs 80 lb Concrete Bags: Yield, Count, and Cost
- Rebar vs Wire Mesh in a Slab: Which One to Use
- Gravel for a Fire Pit Area: Best Types and Depth
- How Much Concrete for a 14 Foot Round Slab?
- How Much Concrete for a 15 Foot Round Slab?
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