Estimate rebar quantity, weight, and cost for concrete reinforcement.
Rebar Reference Guide
Rebar reinforcement prevents concrete cracking and adds tensile strength. Choosing the right size and spacing is critical for structural integrity.
| Rebar Size | Diameter | Weight/ft | Common Use |
|---|---|---|---|
| #3 | 3/8 in | 0.376 lb | Sidewalks, light slabs |
| #4 | 1/2 in | 0.668 lb | Residential slabs, patios |
| #5 | 5/8 in | 1.043 lb | Driveways, garage floors |
| #6 | 3/4 in | 1.502 lb | Foundations, structural |
Frequently Asked Questions
How much rebar do I need for a concrete slab?
For a standard grid pattern with 12-inch spacing on a 10×10 slab, you need about 22 bars (11 each direction). Total linear feet depends on slab dimensions and spacing. Add 10% for overlap and waste.
What size rebar should I use?
#3 (3/8 inch) for light residential work like sidewalks. #4 (1/2 inch) for residential slabs and patios. #5 (5/8 inch) for driveways and garage floors. #6+ for structural and commercial applications.
What is standard rebar spacing?
Common spacings are 12 inches on center for residential slabs, 8 inches for driveways and structural slabs, and 6 inches for heavy-duty applications. Closer spacing provides more strength.
How much does rebar cost?
#3 rebar: $0.25-0.50/ft. #4 rebar: $0.35-0.75/ft. #5 rebar: $0.50-1.00/ft. Standard 20-foot lengths cost $5-20 per bar depending on size. Prices fluctuate with steel markets.
How much overlap do I need when tying rebar?
The standard overlap (lap splice) is 40 times the bar diameter. For #4 rebar (1/2 inch), that’s 20 inches. For #5 rebar, it’s 25 inches. Always tie overlaps securely with rebar tie wire.
Do I need rebar in a 4-inch slab?
For a basic patio or walkway, wire mesh is usually sufficient. For a driveway or garage floor (even at 4 inches), rebar is recommended. For any slab bearing structural loads, rebar is essential.
What are rebar chairs?
Rebar chairs (or supports) are plastic or wire stands that hold rebar at the correct height within the concrete form. They ensure the rebar sits in the middle or lower third of the slab for optimal strength.
Can I use wire mesh instead of rebar?
Wire mesh (welded wire fabric) works for thin slabs under light loads — patios, sidewalks, and interior floors. Rebar is stronger and preferred for driveways, structural slabs, footings, and any load-bearing application.
How do I calculate rebar for a footer?
Standard residential footings use 2-3 continuous horizontal bars with vertical stirrups every 12-18 inches. Calculate linear feet of horizontal bars times the number of bars, plus stirrup lengths and quantities.
What is epoxy-coated rebar?
Epoxy-coated (green) rebar has a corrosion-resistant coating for use in concrete exposed to moisture, salt, or chemicals — bridges, marine structures, pool decks, and foundations in wet soil conditions.