Free Tool
Rebar & Wire Mesh Calculator
Calculate how many rebar sticks or wire mesh sheets you need for your concrete slab, including overlap allowance.
Slab Dimensions
Rebar Options
Typical: 24-40× bar diameter
Wire Mesh Options
Typical: 6" (one square) overlap between sheets
Rebar vs. Wire Mesh: When to Use Each
Both rebar and welded wire mesh (WWM) reinforce concrete, but they serve different purposes:
Rebar
- Structural reinforcement for load-bearing slabs
- Required in thickened edges and footings
- Better for crack control in large slabs
- Placed in a grid pattern at specified spacing
- Common: #4 bars at 12" OC both ways
Wire Mesh
- Temperature and shrinkage crack control
- Suitable for non-structural slabs (patios, sidewalks)
- Faster to install than individual rebar
- Available in sheets (5×10 ft) or rolls
- Common: 6×6 W1.4/W1.4 (6" grid, 10 gauge)
Rebar Size Reference
| Bar Size | Diameter | Weight (lb/ft) | Common Use |
|---|---|---|---|
| #3 | 3/8" | 0.376 | Stirrups, light slabs |
| #4 | 1/2" | 0.668 | Residential slabs, footings |
| #5 | 5/8" | 1.043 | Footings, grade beams |
| #6 | 3/4" | 1.502 | Heavy footings, walls |
| #7 | 7/8" | 2.044 | Structural elements |
| #8 | 1" | 2.670 | Heavy structural |
Lap Splice Requirements
When rebar sticks aren't long enough to span the full slab dimension, they must overlap (lap splice). The minimum overlap is typically 40 times the bar diameter — so a #4 bar (1/2" diameter) needs at least 20 inches of overlap. Most contractors round up to 24 inches for #4 bars.
Track every stick and sheet
ConstructiveCore's inventory management tracks rebar, mesh, and all your materials by job — so you always know what's on hand and what to order.