🛡️ Galvanized Steel Coating Thickness Chart
Complete zinc coating weight-to-thickness conversion table. Cross-reference ASTM A653, EN 10346, JIS G3302, and AS 1397 designations. Convert g/m² to microns instantly.
🔄 Coating Thickness Converter
Enter any one value below — the other fields update automatically.
📊 Coating Thickness Visual Comparison
Relative zinc coating thickness at a glance — thicker coating = longer corrosion protection life.
ASTM A653 / A653M — Hot-Dip Galvanized
ASTM| Designation | Coating Weight (oz/ft²) | Coating Weight (g/m²) | Per Side (g/m²) | Thickness/Side (μm) | Typical Application |
|---|---|---|---|---|---|
| G30 | 0.30 | 90 | 45 | 6.3 | Indoor Appliances, ductwork |
| G40 | 0.40 | 120 | 60 | 8.4 | Indoor Light fabrication |
| G60 | 0.60 | 180 | 90 | 12.6 | Outdoor Roofing, framing |
| G90 Most Common | 0.90 | 275 | 137.5 | 19.3 | Outdoor Construction, roofing, HVAC |
| G115 | 1.15 | 350 | 175 | 24.5 | Heavy Agricultural, highway |
| G140 | 1.40 | 427 | 213.5 | 29.9 | Heavy Exposed structural |
| G165 | 1.65 | 503 | 251.5 | 35.2 | Heavy Corrugated culvert |
| G185 | 1.85 | 564 | 282 | 39.5 | Marine Harsh environment |
| G210 | 2.10 | 640 | 320 | 44.8 | Marine Coastal, industrial |
| G235 | 2.35 | 717 | 358.5 | 50.2 | Marine Max protection |
EN 10346 — European Standard (Z Designation)
EN| Designation | Coating (g/m²) Both Sides | Per Side (g/m²) | Thickness/Side (μm) | ≈ ASTM | Typical Application |
|---|---|---|---|---|---|
| Z100 | 100 | 50 | 7.0 | ≈ G30 | Indoor Interior panels |
| Z140 | 140 | 70 | 9.8 | ≈ G40 | Indoor Appliances, HVAC |
| Z180 | 180 | 90 | 12.6 | ≈ G60 | Outdoor Light roofing |
| Z200 | 200 | 100 | 14.0 | — | Outdoor General purpose |
| Z225 | 225 | 112.5 | 15.8 | — | Outdoor Roofing, cladding |
| Z275 Most Common | 275 | 137.5 | 19.3 | ≈ G90 | Outdoor Construction, roofing |
| Z350 | 350 | 175 | 24.5 | ≈ G115 | Heavy Agricultural, highway |
| Z450 | 450 | 225 | 31.5 | ≈ G140–G165 | Heavy Structural, utility |
| Z600 | 600 | 300 | 42.0 | ≈ G185–G210 | Marine Max protection |
JIS G3302 — Japanese Standard (Z Designation)
JIS| Designation | Coating (g/m²) Both Sides | Per Side (g/m²) | Thickness/Side (μm) | ≈ ASTM / EN | Typical Application |
|---|---|---|---|---|---|
| Z06 | 60 | 30 | 4.2 | — | Auto Automotive panels |
| Z08 | 80 | 40 | 5.6 | — | Auto Automotive parts |
| Z10 | 100 | 50 | 7.0 | ≈ G30 / Z100 | Indoor Appliances |
| Z12 | 120 | 60 | 8.4 | ≈ G40 / Z140 | Indoor General indoor |
| Z18 | 180 | 90 | 12.6 | ≈ G60 / Z180 | Outdoor Roofing |
| Z20 | 200 | 100 | 14.0 | ≈ Z200 | Outdoor General outdoor |
| Z22 | 220 | 110 | 15.4 | ≈ Z225 | Outdoor Cladding |
| Z27 Common | 270 | 135 | 18.9 | ≈ G90 / Z275 | Outdoor Construction |
| Z35 | 350 | 175 | 24.5 | ≈ G115 / Z350 | Heavy Highway, bridges |
| Z45 | 450 | 225 | 31.5 | ≈ G165 / Z450 | Heavy Extreme exposure |
AS 1397 — Australian Standard (Z Designation)
AS| Designation | Coating (g/m²) Both Sides | Per Side (g/m²) | Thickness/Side (μm) | ≈ ASTM / EN | Typical Application |
|---|---|---|---|---|---|
| Z100 | 100 | 50 | 7.0 | ≈ G30 / Z100 | Indoor |
| Z200 | 200 | 100 | 14.0 | ≈ G60 / Z200 | Outdoor |
| Z275 Common | 275 | 137.5 | 19.3 | ≈ G90 / Z275 | Outdoor Construction |
| Z350 | 350 | 175 | 24.5 | ≈ G115 / Z350 | Heavy |
| Z450 | 450 | 225 | 31.5 | ≈ G165 / Z450 | Heavy Agricultural |
| Z600 | 600 | 300 | 42.0 | ≈ G210 / Z600 | Marine |
🔄 Quick Cross-Reference: ASTM vs EN vs JIS vs AS
Find equivalent zinc coating designations across international standards at a glance.
| g/m² (Both Sides) | μm / Side | ASTM A653 | EN 10346 | JIS G3302 | AS 1397 |
|---|---|---|---|---|---|
| 60 | 4.2 | — | — | Z06 | — |
| 80 | 5.6 | — | — | Z08 | — |
| 90–100 | 7.0 | G30 | Z100 | Z10 | Z100 |
| 120–140 | 8.4–9.8 | G40 | Z140 | Z12 | — |
| 180 | 12.6 | G60 | Z180 | Z18 | — |
| 200 | 14.0 | — | Z200 | Z20 | Z200 |
| 275 | 19.3 | G90 ⭐ | Z275 ⭐ | Z27 | Z275 ⭐ |
| 350 | 24.5 | G115 | Z350 | Z35 | Z350 |
| 450 | 31.5 | G140–G165 | Z450 | Z45 | Z450 |
| 600 | 42.0 | G185–G210 | Z600 | — | Z600 |
📋 Coating Selection Guide by Application
Choose the right zinc coating weight based on your project environment and expected service life.
Indoor / Dry Environment
Appliances, HVAC ductwork, interior wall framing, electrical enclosures. Low corrosion risk — thinnest coating sufficient.
General Construction
Roofing, wall cladding, purlins, C/Z sections, light steel framing, commercial buildings. The most widely specified coating weight globally.
Agricultural / Rural
Farm buildings, silos, fencing, grain storage, livestock shelters. Moderate-to-harsh exposure with chemical contact (fertilizers, manure).
Coastal / Marine / Industrial
Coastal buildings, offshore platforms, chemical plants, power stations. Salt spray, acid rain, and industrial pollutants require maximum protection.
Automotive
Auto body panels, structural members, underbody components. Thin, uniform coating for paintability and spot weldability. Electro-galvanized or one-side coating common.
Pre-Painted (PPGI/PPGL Base)
Color-coated roofing and cladding. The zinc layer provides base corrosion protection under the paint system. Z120–Z275 most common for exterior PPGI.
📐 Conversion Formulas
Thickness (μm per side) = Coating weight (g/m² per side) ÷ Zinc density (7.14 g/cm³) × 10
Or simplified:
Thickness (μm) ≈ g/m² (per side) × 0.14
Total both sides → per side:
Per side (g/m²) = Total both sides (g/m²) ÷ 2
g/m² → oz/ft²:
oz/ft² = g/m² × 0.003277
μm → mils:
mils = μm × 0.03937
Frequently Asked Questions
G90 is the ASTM A653 designation meaning the total zinc coating weight is 0.90 oz/ft² (approximately 275 g/m²) on both sides combined. Z275 is the equivalent EN 10346 designation meaning 275 g/m² total. This translates to about 137.5 g/m² per side, or approximately 19.3 microns (μm) thickness per side. G90/Z275 is the most commonly specified coating weight for general construction and roofing applications worldwide.
To convert: Thickness (μm) = Coating weight per side (g/m²) ÷ 7.14, where 7.14 g/cm³ is the density of zinc. A simplified formula: μm ≈ g/m² per side × 0.14. For example, Z275 = 275 g/m² total = 137.5 g/m² per side ÷ 7.14 = 19.3 μm per side. Remember: the Z/G number refers to total coating on both sides — divide by 2 to get per-side values.
For most roofing applications, G90 / Z275 (19.3 μm per side) is the industry standard and provides 20-30 years of corrosion protection in normal environments. In coastal, industrial, or high-humidity regions, upgrade to G115 / Z350 (24.5 μm) or G165 / Z450 (31.5 μm). For PPGI/PPGL color-coated roofing, a Z120-Z275 base coat plus paint system (PE/SMP/PVDF) can extend total service life to 15-25+ years.
They are essentially equivalent designations from different standards: G90 = ASTM A653 (American, 0.90 oz/ft²), Z275 = EN 10346 (European, 275 g/m²), Z27 = JIS G3302 (Japanese, 270 g/m²). All represent approximately the same total zinc coating weight (~270-275 g/m² both sides, ~19 μm per side). The slight numerical differences (270 vs 275) are within normal manufacturing tolerances.
Zinc coating life depends on environment: In rural/dry conditions, G90/Z275 (19μm) lasts 30-50+ years. In suburban environments: 20-30 years. In industrial areas: 10-20 years. In coastal/marine environments: 5-15 years. As a rule of thumb, each additional 1 μm of zinc coating extends life by approximately 1-2 years in moderate environments. For harsh environments, consider thicker coatings (Z450-Z600) or galvalume (AZ) coatings.
Galvalume (GL/AZ) is an aluminum-zinc alloy coating (55% Al, 43.4% Zn, 1.6% Si), while galvanized (GI) is pure zinc. Galvalume offers 2-4× longer corrosion life than equivalent-weight galvanized in most environments, especially for roofing. Common galvalume designations: AZ150 (150 g/m²) ≈ performance of Z275 galvanized. However, galvalume is less suitable for cut-edge and scratch protection compared to pure zinc. AZ designation follows ASTM A792 / EN 10346 standards.
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