Mesh basics
Welded wire mesh sizes: gauge, W-number and steel area
A mesh designation like 6x6-W2.9xW2.9 gives the spacing (6 × 6 in · 152 × 152 mm) and the wire cross-section in hundredths of a square inch (W2.9 = 0.029 in² · 18.7 mm²). The common concrete sizes are W1.4 (10 gauge), W2.9 (6 gauge) and W4.0 (4 gauge). Standard 8 × 20 ft flat sheets cover 160 ft² gross and approximately 142 ft² after laps.
How to read a mesh designation
Reinforcing mesh is designated by spacing followed by wire size:
6x6-W2.9xW2.9
- 6x6: Spacing of the wires in inches. The first number gives longitudinal wire spacing (6 in · 152 mm), and the second gives transverse wire spacing (6 in · 152 mm).
- W2.9xW2.9: Cross-sectional area of each wire in hundredths of a square inch. The letter W denotes smooth plain wire; the letter D denotes deformed wire with cold-formed ribs.
- Older notation: Older structural drawings refer to wire gauge:
6x6-6/6indicates 6 in spacing with 6 gauge wire both ways, equivalent to6x6-W2.9xW2.9. - Metric notation: Canadian and metric engineering drawings use millimetres:
152x152-MW18.7xMW18.7, where MW represents metric plain wire area in square millimetres (18.7 mm² = 0.029 in²).
Current manufacturing and testing follow ASTM A1064/A1064M and CSA G30.5 (ASTM).
Wire gauge to W-number conversion chart
The table below provides physical dimensions across common wire sizes used in slabs on ground, toppings, and precast elements per WRI WWR-500-R-26:
| Gauge (US Steel Wire) | W-Number (Imperial) | Metric Area (CSA MW) | Wire Diameter | Wire Area | Nominal Wire Weight |
|---|---|---|---|---|---|
| 10 | W1.4 | MW9.1 | 0.135 in (3.43 mm) | 0.014 in² (9.03 mm²) | 0.0476 lb/ft (0.0708 kg/m) |
| 8 | W2.1 | MW13.5 | 0.162 in (4.11 mm) | 0.0206 in² (13.3 mm²) | 0.0700 lb/ft (0.1042 kg/m) |
| 6 | W2.9 | MW18.7 | 0.192 in (4.88 mm) | 0.0290 in² (18.7 mm²) | 0.0986 lb/ft (0.1467 kg/m) |
| 4 | W4.0 | MW25.8 | 0.225 in (5.72 mm) | 0.0400 in² (25.8 mm²) | 0.1360 lb/ft (0.2024 kg/m) |
| 2 | W5.5 | MW35.5 | 0.265 in (6.73 mm) | 0.0550 in² (35.5 mm²) | 0.1870 lb/ft (0.2783 kg/m) |
| 0 | W7.5 | MW48.4 | 0.309 in (7.85 mm) | 0.0750 in² (48.4 mm²) | 0.2550 lb/ft (0.3795 kg/m) |
Diameters are derived mathematically from cross-sectional area and steel density (490 lb/ft³ · 7,850 kg/m³). Lower gauge numbers indicate thicker, heavier wire.
Look up any gauge, W-number and steel area with the gauge lookup on the calculator page.
Steel area (As) for common grid spacings
Design engineers specify steel area per unit width (As) to satisfy subgrade drag equations and crack control requirements. With 6 in (152 mm) spacing, there are exactly two wires per foot of slab width:
| Mesh Designation | Spacing (in · mm) | Steel Area Each Way (As) | Steel Area Metric | Weight per 100 ft² | Weight per 8 × 20 ft Sheet |
|---|---|---|---|---|---|
| 6×6 W1.4/W1.4 (10 ga) | 6 × 6 · 152 × 152 | 0.028 in²/ft | 59 mm²/m | 19 lb (0.93 kg/m²) | ~32 lb (14.5 kg) |
| 6×6 W2.1/W2.1 (8 ga) | 6 × 6 · 152 × 152 | 0.041 in²/ft | 87 mm²/m | 29 lb (1.42 kg/m²) | ~46 lb (21 kg) |
| 6×6 W2.9/W2.9 (6 ga) | 6 × 6 · 152 × 152 | 0.058 in²/ft | 123 mm²/m | 39 lb (1.90 kg/m²) | ~66 lb (30 kg) |
| 6×6 W4.0/W4.0 (4 ga) | 6 × 6 · 152 × 152 | 0.080 in²/ft | 169 mm²/m | 54 lb (2.64 kg/m²) | ~91 lb (41 kg) |
| 4×4 W2.9/W2.9 (6 ga) | 4 × 4 · 102 × 102 | 0.087 in²/ft | 184 mm²/m | 59 lb (2.88 kg/m²) | ~99 lb (45 kg) |
| 4×4 W4.0/W4.0 (4 ga) | 4 × 4 · 102 × 102 | 0.120 in²/ft | 254 mm²/m | 82 lb (4.00 kg/m²) | ~137 lb (62 kg) |
| 12×12 W4.0/W4.0 (4 ga) | 12 × 12 · 305 × 305 | 0.040 in²/ft | 85 mm²/m | 27 lb (1.32 kg/m²) | ~46 lb (21 kg) |
Weights listed are nominal wire weights. Real sheet weights vary slightly based on side and end wire overhangs (typically 1 to 2 in · 25 to 50 mm beyond the perimeter welds).
Sheet dimensions and coverage calculation
Structural flat sheets are manufactured in 8 × 20 ft (2.44 × 6.10 m) dimensions for efficient flatbed transport and job-site crane handling:
- Gross area per sheet: 160.0 ft² (14.86 m²).
- Net coverage per sheet (after 8 in · 203 mm side and end laps): Approximately 142.0 ft² (13.19 m²).
- Bundle counts: 6 gauge sheets are packaged in bundles of 50 sheets (~3,300 lb · 1,500 kg); 4 gauge sheets are packaged in bundles of 50 sheets (~4,550 lb · 2,060 kg).
How to verify mesh dimensions on site
- Verify wire spacing: Measure centre-to-centre across 5 to 10 consecutive wire intersections with a steel tape and divide by the count. Do not measure the clear inside gap between wires.
- Measure wire diameter: Use a dial or digital caliper on a clean, straight section of wire at least 25 mm (1 in) away from a welded intersection. Check against the wire diameter column above.
- Verify overall sheet size: Measure from the outer tip of the longitudinal wires and transverse wires to verify total width and length including edge overhangs.
What we carry
We supply 6 gauge (6×6 W2.9/W2.9) and 4 gauge (6×6 W4.0/W4.0) flat sheets in standard 8 × 20 ft panels. Our mesh meets ASTM A1064/A1064M and CSA G30.5, and independent lab testing backs that up (see Quality and testing). 10 gauge (6×6 W1.4/W1.4) is open for registering interest. For guidance on selecting between these sizes, see 4 vs 6 vs 10 gauge wire mesh.
- ASTM A1064/A1064M, Standard specification for carbon-steel wire and welded wire reinforcement for concrete. Link
- CSA G30.5, Welded steel wire fabric for concrete reinforcement. CSA Group.
- Wire Reinforcement Institute (2026), Manual of Standard Practice: Structural Welded Wire Reinforcement (WWR-500-R-26). Link
- Wire Reinforcement Institute, Detail WWR.1: General Notes. Link
Questions
What do the numbers mean on welded wire mesh?
The first pair (such as 6x6) is the wire spacing in inches; the second pair (such as W2.9xW2.9) is the cross-sectional area of each wire in hundredths of a square inch, where W stands for plain wire.
What gauge is 6x6 W2.9xW2.9?
6 gauge steel wire, with a diameter of 4.88 mm (0.192 in).
What is the difference between W1.4 and W2.9 wire mesh?
W2.9 (6 gauge) provides more than double the steel area of W1.4 (10 gauge): 0.058 in²/ft (123 mm²/m) versus 0.028 in²/ft (59 mm²/m).
What is the thickest welded wire mesh?
Standard structural wire sizes reach up to W20 or W31 (diameter 12.8 mm to 16.0 mm / 0.50 to 0.63 in). For flat sheets carried for slabs on ground, 4 gauge (W4.0, diameter 5.72 mm / 0.225 in) is the heaviest common size.