Welded wire mesh, sometimes called wire reinforcement or WWF, is a grid of cold-drawn steel wires welded at every crossing. It is a common way to reinforce driveways, garage floors and patios against shrinkage cracking because a sheet covers a lot of area quickly. This calculator tells you how many sheets cover your slab and how much steel they contain.
How to use the concrete reinforcing mesh calculator
- Enter the slab length and width.
- Choose the mesh. The usual choice for residential slabs is 6×6 – W1.4×W1.4, with heavier styles when specified.
- Enter the sheet size sold by your supplier — 5 × 10 ft is the default.
- Add an allowance for the overlap at the seams and for cut-offs.
Wire mesh formula
Weight per 100 sq ft = 2 directions × (12 ÷ spacing) × (W ÷ 100) × 12 × 0.2836 × 100
Each foot of slab has 12 ÷ spacing wires in each direction. The W number gives each wire’s area, so multiplying by 12 inches of length and the density of steel (0.2836 lb/in³) gives the steel in a square foot. Because the formula uses nominal wire area, weights may differ a little from a manufacturer’s published figure.
Worked example: a 20 × 20 ft slab
- Area: 20 × 20 = 400 sq ft. With 10% overlap and cuts: 440 sq ft.
- Sheets of 5 × 10 ft (50 sq ft): 440 ÷ 50 = 8.8, which rounds up to 9 sheets.
- Steel in 6×6 – W1.4: 19.1 lb per 100 sq ft, so the 9 sheets weigh about 86 lb.
Weight of common mesh styles (nominal wire area)
| Mesh | lb per 100 sq ft | lb per 5 × 10 ft sheet |
|---|---|---|
| 6×6 – W1.4 × W1.4 (10 ga) | 19.1 | 9.5 |
| 6×6 – W2.9 × W2.9 (6 ga) | 39.5 | 19.7 |
| 6×6 – W4.0 × W4.0 (4 ga) | 54.5 | 27.2 |
| 4×4 – W1.4 × W1.4 | 28.6 | 14.3 |
| 4×4 – W4.0 × W4.0 | 81.7 | 40.8 |
Using mesh correctly
- Position matters. Mesh should be in the middle to upper third of the slab thickness. Use chairs; pulling mesh up with a rake during the pour is unreliable.
- Overlap. Lap adjacent sheets by at least one full opening and tie them; do not leave butt joints.
- Join with control joints. Mesh does not prevent cracks; it holds cracks tight. Saw or tool control joints as well.
- Fibers. Some contractors use synthetic fibers in the mix in place of mesh; ask what your project requires.
For heavier or structural reinforcement use bars; the Rebar Material Calculator works out a grid at any spacing and the Rebar Weight Calculator gives weights. The concrete volume itself comes from the Concrete Calculator.
Frequently asked questions
How many sheets of wire mesh do I need?
Divide the slab area plus an overlap allowance by the area of one sheet and round up. A 20 × 20 ft slab is 400 sq ft; with 10% extra that is 440 sq ft, or 9 sheets of 5 × 10 ft mesh.
What does 6×6 W1.4×W1.4 mean?
The first numbers are the wire spacing in inches in each direction (6 in). The W number is the wire cross-sectional area in hundredths of a square inch: W1.4 = 0.014 in², which is about 10-gauge wire.
How much should mesh sheets overlap?
Sheets are commonly lapped by at least one full mesh opening plus a small extra amount, around 6 inches for 6×6 mesh, and tied together. Your plans or engineer may require more.
Is mesh as good as rebar?
Mesh controls shrinkage cracking in light slabs on grade, but it does not replace rebar where structural reinforcement is required. It also must be held in the middle of the slab, not left lying on the base.
Is mesh sold in rolls or sheets?
Both. Rolls are easier to transport but must be flattened. Sheets stay flat and are easier to place, which is why the calculator counts sheets of an editable size.