Rebar Calculator
Calculate rebar requirements for concrete slabs, foundations, and structures. Get accurate estimates for rebar quantity, weight, and costs.
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Pricing Updated:
For Homeowners: Get a quick cost range with just a few measurements. Perfect for budgeting and comparing contractor quotes.
Quick Mode: Get a fast estimate with basic dimensions. Perfect for homeowners and initial budgeting.
Typical Rebar Costs by Size
| Rebar Size | $/Linear Foot | Weight (lbs/ft) | Common Application |
|---|---|---|---|
| #3 (3/8") | $0.65 ā $1.10 | 0.376 | Sidewalks, light slabs, stirrups |
| #4 (1/2") | $0.90 ā $1.55 | 0.668 | Residential slabs, driveways, patios |
| #5 (5/8") | $1.40 ā $2.40 | 1.043 | Footings, grade beams, retaining walls |
| #6 (3/4") | $2.00 ā $3.40 | 1.502 | Foundation walls, columns, heavy structural |
| #7 (7/8") | $2.75 ā $4.60 | 2.044 | Commercial foundations, bridge decks |
| #8 (1") | $3.55 ā $6.00 | 2.670 | Heavy commercial, infrastructure |
Prices are for black (uncoated) rebar. Epoxy coating adds 50%, galvanized 100%, stainless steel 300%. Sold in standard 20 ft bars.
Assumptions & Sources
Assumptions
- Bar length: Standard 20 ft bars with 10% waste factor for cutting, bending, and lap splices. Custom-cut lengths reduce waste but increase per-foot cost.
- Spacing: Quick mode defaults to 18" O.C. (on center) both ways ā standard for 4-6" residential slabs. Structural applications may require 12" or tighter per engineering plans.
- Concrete cover: 3" minimum from edge of slab, calculated by subtracting 6" total from each dimension. Reduced cover in quick mode for simplicity.
- Labor rates: $0.50-1.00/lb of rebar for tying, placing, and supporting. Includes chair placement and tie wire. Complex layouts (columns, beams) cost more per pound.
- Regional multiplier: ZIP-code-based adjustment using RSMeans 2025 regional cost indices applied to both materials and labor.
Last updated: February 2026
Pro Tips from a Construction PM
- Lap splice = 40Ć bar diameter: That's 20" for #4 rebar, 25" for #5. Short splices are the #1 inspection failure. The inspector will make you cut it out and redo ā and that means chipping concrete if you already poured.
- Chair spacing for proper cover: Set chairs every 3-4 feet in a grid. Rebar must sit at the right elevation ā typically 2-3" from slab bottom. Rebar sitting on the ground does nothing structurally.
- Get inspection before the pour: Once concrete covers rebar, there's no verifying spacing, cover, or splice lengths. A failed post-pour inspection means core drilling or demolition.
- Tie wire vs. mechanical couplers: Wire ties are fine for residential flat work ā hit every other intersection. For critical structural joints (columns, grade beams, retaining walls), mechanical couplers develop 100% bar strength vs. 80% for lap splices.
- Light rust is actually fine: Surface rust improves concrete bonding. But scaled, flaking rust means lost cross-section ā replace those bars. Store rebar off the ground on dunnage to prevent this.
Related Calculators
- Concrete Calculator ā Estimate concrete volume and cost for the slab, footing, or wall your rebar is reinforcing.
- Foundation Repair Calculator ā Calculate foundation repair costs if rebar work is part of structural remediation.
- Excavation Calculator ā Figure excavation costs for footings, grade beams, and foundation trenches that need rebar.
Rebar Calculator by State
Get rebar cost estimates with state-specific regional pricing:
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