Rebar Estimator (Rough)

Estimate slab rebar length using grid spacing, optional perimeter bars, and a waste factor for quick planning takeoffs. For slab thickness planning, see the slab thickness guide. Concrete reinforcement helps prevent cracks, but pavers use base compaction. See full differences in our Concrete vs. Pavers comparison.

Inputs

Tip: Typical slab rebar spacing is 12–18 inches; tighter spacing can increase load capacity but raises material and labor.

Quick Reference: Rebar Spacing Guide

Spacing (O.C.)Typical UseQuick Note
12 inHeavier duty slabsMore steel, tighter crack control
16 inCommon residential slabsBalanced material and performance
18 inLight-duty flatworkLower steel count where allowed

Spacing guidance is for planning only. Confirm reinforcement layout with your project drawings and local code.

Results

Total linear feet (with waste)
336.6 ft
11 bars running lengthwise • 13 bars running widthwise
20-ft sticks estimate
17
Includes 44 ft of perimeter rebar.

Rough estimate; not a structural design.

Want a full breakdown of delivery fees, short loads, PSI pricing, and what affects ready-mix rates? See our ready-mix cost guide.

Assumptions

  • Grid assumes straight bars running full slab length and width.
  • Spacing is measured center-to-center.
  • Perimeter adds a single continuous bar around the slab.
  • Waste factor accounts for laps, cuts, and handling loss.

Example

A 12 ft × 10 ft slab at 12 in spacing with perimeter rebar is about 336.6 ft of bar, or roughly 17 20-ft sticks.

Related Concrete Tools

Concrete Estimating Guide

Related Guides