Wire Mesh Calculator: Sheets and Rolls for a Slab

How do you calculate how much wire mesh you need?

Work out how many sheets fit across each side of the slab, allowing for the overlap where sheets meet, and multiply. Try the sheet both ways round and keep the layout that uses fewer sheets. Rolls work the same way, as strips the width of the roll.

Pieces across a side = 1 if the side ≤ piece size, otherwise (side − lap) ÷ (piece size − lap), rounded up
Sheets = pieces along the length × pieces across the width
Steel weight = mesh area bought × weight per ft²

The mesh also stops short of the slab edge so it has concrete cover. That makes the real mesh area slightly smaller than the slab, so the count errs on the safe side. Cover distances are on your drawings.

How many sheets or rolls for common slab sizes?

The table uses 6 in laps and no extra allowance. Rolls are 7 ft wide strips cut from 50, 100 or 200 ft rolls, matching sizes in a published state-contract product list; ask your supplier what they stock.

Laps matter more than you might think. The 24 × 24 ft slab needs 6 sheets of 8 × 20 ft with no lap but 8 with a 6 in lap, because the overlap pushes one side past what three sheets cover. Whichever you buy, the mesh has to lie flat on its supports at the planned height.

What do wire mesh styles like 6x6 W1.4/W1.4 mean?

The first pair of numbers is the wire spacing in inches, the second pair the wire sizes. In the Wire Reinforcement Institute’s nomenclature, W is plain (smooth) wire, D is deformed wire, and the number is the cross-section in hundredths of a square inch, so W1.4 is 0.014 in². The WRI Manual of Standard Practice notes that welded wire reinforcement is governed by ASTM A1064, which covers both plain and deformed wire.

Weights are computed: wire length per ft² (two directions × 12 ÷ spacing) × wire area × 3.40 lb per ft per in² of steel. The 3.40 factor comes from the ASTM A615 #4 bar, 0.668 lb/ft for a 1/2 in bar, and works out to about 490 lb/ft³ of steel. The old gauge names are from the state-contract product list in the sources; the W number is the precise size.

How much does wire mesh weigh?

About 19 lb per 100 ft² for 6×6 W1.4/W1.4 and about 40 lb for 6×6 W2.9/W2.9. Multiply by the mesh area you buy, not the slab area, because laps and offcuts are paid for too. A 7 × 100 ft roll of W1.4 is about 133 lb (60.5 kg); a 7 × 200 ft roll about 267 lb (121 kg).

Wire mesh calculator in metric

Enter the slab in feet (1 m = 3.2808 ft) and the lap in inches (150 mm = 5.9 in). The weight result also shows kg/m².

Where does wire mesh go in a concrete slab?

At the height shown on your drawings, held there on supports through the pour. This page counts material; it does not decide whether a slab needs mesh, which style, or where it sits. Those are design decisions for the person responsible for the slab, under your local code.

What the published guidance says about placement:

• Support it, do not pull it up. ACI 302.1R-15 (Section 5.2.4) says welded wire reinforcement should not be placed on the ground and pulled up after the concrete is placed, nor walked in afterwards. Supports must be close enough that the mesh cannot be forced out of position by foot traffic during construction.
• Support spacing. ACI 301-16 limited support spacing to 12 in for welded wire smaller than W4.0 or D4.0; ACI 301-20 says supports are as indicated in the contract documents. The WRI Manual reprints TF 702’s suggested spacings, 2 to 3 ft or less for light mesh at under 12 in wire spacing, as a starting point between designer and contractor. Your project specification decides which applies.
• Stable supports. ACI 302.1R-15 says proper support spacing is necessary to keep the mesh at the proper elevation; use the supports your plans specify.
• Sheet widths. WRI notes that sheets are often limited to 102 in (8.5 ft) wide for road transport, which is why 8 ft sheets are common.

Common wire mesh estimating mistakes

• Buying slab area, not mesh area. Laps and cut-offs add area: the 20 × 20 ft example buys 480 ft² for 400 ft², and a 12 × 12 ft slab uses two 8 × 20 ft sheets (320 ft²) for 144 ft².
• Forgetting the lap. On the 24 × 24 ft slab a 6 in lap adds two sheets.
• Ignoring weight. A bundle of 8 × 20 ft W2.9 sheets is heavy to unload by hand at 63 lb each.
• Choosing the style by price. W2.9 carries about twice the steel of W1.4 at the same spacing. Use the style on your plans.
• Treating mesh as a substitute for a design. Mesh, rebar, fibres or none at all is a design choice; for slab joints, thickness and base, see the concrete slab calculator and your local code.

All results are material estimates only. Reinforcement type, size, laps and position must follow your drawings, local code and a licensed engineer where required.