Pouring a 24x24 Garage Slab: Sizing & Estimation

A 24x24 concrete slab provides 576 square feet of surface, representing the standard layout footprint for a full double-car garage, detached backyard workshop, or farm storage shed pad. Because a slab of this scope holds heavy equipment and vehicles, planning the volume and structural detailing is critical.

Need helper estimates for alternative sizes? Try our dynamic Concrete Slab Calculator. For backyard patios, check our specialized Concrete Patio Calculator.

Concrete Yards & Bag Estimates for 24x24 Slabs

At a standard 4-inch depth, a 24x24 slab requires **7.11 cubic yards** of wet concrete. Applying the recommended 10% waste buffer brings the total volume needed to **7.82 cubic yards**. If you plan to park heavy trucks or install car lifts, increasing the depth to 6 inches is highly recommended.

If you are buying pre-packaged bags to mix on-site (a massive project that is usually better handled via ready-mix delivery trucks), the bag requirements are:

• 80 lb Bags: You will need 352 bags (each yielding 0.60 cu. ft.).
• 60 lb Bags: You will need 470 bags (each yielding 0.45 cu. ft.).

Important Tips for Pouring a 24x24 Garage Slab

1. Pour Thickened Slab Edges: A monolithic slab (often called a slab-on-grade) should feature edges that are dug 12 inches deep and 12 inches wide around the perimeter. This creates a footing that carries the load of the garage walls and roof framing.
2. Install a Vapor Barrier: Lay down a 6-mil polyethylene sheet under the slab before pouring. This blocks moisture from wicking up from the ground through the concrete, keeping your garage dry and preventing rust on tools or vehicles.
3. Place a Grid of Steel Rebar: Steel reinforcement is mandatory for vehicle slabs. Install #3 or #4 rebar in a grid spaced 12 to 16 inches apart, elevated on concrete block chairs to sit in the center of the pour depth.