How Much Rebar for a 20x20 ft Garage Slab?
A 20×20 ft two-car garage slab with 12-inch rebar spacing and 20-foot bars requires approximately 42 bars.
How to use this tool
- Enter the slab dimensions in feet.
- Set the rebar spacing (12 inches is standard for residential slabs).
- Enter the standard bar length you'll purchase (typically 20 ft).
- The result shows total linear footage and number of bars to buy.
Find out how many rebar bars you need to reinforce a standard 20×20 foot two-car garage concrete floor slab.
Frequently asked questions
- How much rebar do I need for a slab?
- For a standard grid pattern with 12-inch spacing, calculate both directions of bars, multiply by the slab dimension in each direction, then add them together.
- What rebar size for a concrete slab?
- #3 rebar (3/8-inch diameter) is standard for residential slabs 4 inches thick. Use #4 (1/2-inch) for 5–6 inch driveways or higher-load applications.