How Much Concrete for a 24 Foot Round Slab?
How much concrete for a 24 foot round slab: about 5.59 cubic yards at 4 inches thick. A circle 24 feet across has a radius of 12 feet and an area of about 452.4 square feet (π × 12²).
Concrete calculator →The circle math
- Radius: 24 ÷ 2 = 12 ft.
- Area: 3.1416 × 12 × 12 = 452.4 sq ft.
- Volume at 4 in: 452.4 × 0.333 = 150.8 cu ft.
- Yards: ÷ 27 = 5.59 yd³.
A round slab takes about 21 percent less concrete than a square of the same width (24x24 would need 7.11 yards at 4 inches).
By thickness
| Thickness | Cubic feet | Cubic yards | Yards +10% | 80 lb bags | 60 lb bags |
|---|---|---|---|---|---|
| 4 in | 150.8 | 5.59 | 6.14 | 252 | 336 |
| 5 in | 188.5 | 6.98 | 7.68 | 315 | 419 |
| 6 in | 226.2 | 8.38 | 9.22 | 377 | 503 |
Forming a circle
Curved forms are usually made from thin hardboard, bender board or kerfed plywood bent around stakes. Drive a center pin and use a string or a board pivot to mark the radius, then set stakes every foot or so around the curve.
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
Radial joints from the center keep cracks in check. On larger circles, a ring joint partway out keeps the outer panels from getting too long and narrow.
Questions people ask
How many yards of concrete for a 24 ft round slab?
About 5.59 cubic yards at 4 inches.
How many square feet is a 24 ft circle?
About 452.4 square feet.
How many 80 lb bags for a 24 ft round slab?
About 252 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.
When is bagged concrete practical?
Usually for jobs under about a cubic yard. Beyond that, mixing dozens of bags by hand gets slow and batches may not blend well.
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 an 18 Foot Round Slab?
- How Much Concrete for a 20 Foot Round Slab?
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