Rebar Calculator
Rebar Calculator
Calculate the exact amount of rebar (reinforcement steel) needed for concrete slabs, footings, walls, and foundations. This professional rebar calculator estimates quantity, spacing, lengths, and costs.
Common Rebar Sizes & Applications:
- #3 (3/8"): residential slabs, light construction
- #4 (1/2"): driveways, sidewalks, small foundations
- #5 (5/8"): house foundations, retaining walls
- #6 (3/4"): heavy foundations, commercial construction
- #7 (7/8"): large foundations, structural beams
- #8 (1"): commercial/industrial applications
Rebar Spacing Guidelines:
- Residential slabs: #4 @ 18" on center both ways
- Driveways: #4 @ 12" on center both ways
- Footings: #4 or #5 @ 12" spacing
- Retaining walls: #5 @ 12" vertical, #4 @ 18" horizontal
Concrete Cover Requirements:
- Slabs on ground: 3" clear cover
- Footings: 3" clear cover (bottom and sides)
- Walls: 2" cover exterior, 3/4" cover interior
- Beams/columns: 1.5" minimum cover
Rebar Lengths & Costs:
- Standard lengths: 20', 40', 60' (20' most common)
- #3 rebar: $8-12 per 20' stick
- #4 rebar: $12-18 per 20' stick
- #5 rebar: $18-25 per 20' stick
- #6 rebar: $25-35 per 20' stick
Rebar Accessories:
- Rebar ties: wire ties to connect intersections
- Chairs/supports: maintain proper spacing from ground
- Couplers: connect rebar pieces end-to-end
- Bending tools: create hooks and bends
Frequently Asked Questions
How much rebar do I need for a 10x10 concrete slab?
For a 10×10 slab with #4 rebar at 18" spacing: approximately 13 pieces of 20' rebar (11 each direction plus extras for cuts/waste).
What size rebar for residential foundation?
#4 or #5 rebar is standard for residential foundations. Use #4 for lighter loads, #5 for heavier loads or challenging soil conditions.
How do I calculate rebar spacing?
Divide slab dimension by desired spacing, add 1. For 10' slab with 18" spacing: (120" ÷ 18") + 1 = 7.7, so use 8 pieces.
Do I need rebar in a 4-inch concrete slab?
Not always required by code, but recommended for durability. Rebar prevents cracking and increases load capacity significantly.
How much does rebar add to concrete cost?
Rebar typically adds 15-25% to concrete material costs but greatly improves strength and longevity of the structure.
Can I bend rebar myself?
Yes, smaller sizes (#3-#5) can be bent with manual tools. Larger sizes require hydraulic benders or professional fabrication.