How much rebar for a 10×10 slab?
Quick Answer
A 10×10 foot slab with #4 rebar on 12-inch centers requires 11 bars running each direction — 22 bars total — at 10 feet each, totaling 220 linear feet of rebar. At typical pricing of $0.60–0.90 per linear foot for #4 rebar, that's $130–200 in rebar materials.
Quick Reference Table
| Slab Size | Rebar (12" spacing, #4) |
|---|---|
| 10×10 ft | 220 lin ft / 22 bars |
| 12×12 ft | 312 lin ft / 26 bars |
| 10×20 ft | 330 lin ft / 33 bars |
| 20×20 ft | 840 lin ft / 42 bars |
| 20×30 ft | 1,240 lin ft / 62 bars |
| 24×24 ft | 1,200 lin ft / 50 bars |
How to Calculate It Yourself
- 1
Choose spacing: residential slabs typically use #4 rebar on 12-inch centers. Driveways and heavier loads use 12" or 8" spacing with #4 or #5 bar.
- 2
Calculate bars per direction: divide slab length by spacing and add 1. For 10 ft on 12" centers: 10 ÷ 1 + 1 = 11 bars per direction.
- 3
Calculate total bars: 11 bars × 2 directions = 22 bars. Each bar is 10 ft long = 220 linear feet total.
- 4
Add 10% for overlap and waste: 220 × 1.10 = 242 linear feet. Round up when ordering.
Pro Tip
Rebar comes in 20-foot sticks. For a 10×10 slab, each 20-foot stick cuts perfectly in half with zero waste. Order 12 sticks (240 lin ft) to cover 22 bars × 10 ft with waste.
Assumptions to Check
Before ordering materials, confirm the dimensions, product coverage, waste factor, and local installation requirements for your project. Manufacturer coverage tables and local code rules can change the final quantity, especially for structural work, exterior projects, and irregular layouts.
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