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Fabrication Reference

Sheet Metal Gauge to mm and inches (Thickness Conversion)

Convert sheet metal gauge numbers to thickness for steel, galvanized steel, and aluminum. Use the tables to see exact inches and millimeters, and pick the right material thickness for your project.

SteelGalvanizedAluminum

Conversion basics

mm = inches × 25.4

inches = mm ÷ 25.4

Gauge values come from material-specific charts. Do not mix steel, galvanized, and aluminum tables.

Need precise conversions?

Use the mm to inches converter for arbitrary thicknesses, then reference the gauge tables to align with stocked sheet sizes.

Open mm to inchesView conversion chart

Reverse lookup — find gauge from thickness

Enter thickness in mm. We will suggest the closest gauge.

mm to inchesConversion chart

Enter a thickness to see suggested gauge in the selected material.

Nominal values only. Coatings and mill tolerances apply; verify with supplier datasheets.

Weight per area estimator

Densities: steel/galvanized ≈ 7850 kg/m³; aluminum ≈ 2700 kg/m³

Using thickness: — enter thickness above

Material: Steel

kg/m²: —

lb/ft²: —

Total weight: —
Total weight: —

Nominal estimates; coatings and alloy variations affect density and thickness.

Steel gauge chart (nominal thickness)

Nominal thickness. Values shown to 4 decimals (in) and 2 decimals (mm).

GaugeThickness (in)Thickness (mm)
30.23916.07
40.22425.69
50.20925.31
60.19434.94
70.17934.55
80.16444.18
90.14953.80
100.13453.42
110.11963.04
120.10462.66
130.08972.28
140.07471.90
150.06731.71
160.05981.52
170.05381.37
180.04781.21
190.04181.06
200.03590.91
210.03290.84
220.02990.76
230.02690.68
240.02390.61
250.02090.53
260.01790.45
270.01640.42
280.01490.38
290.01350.34
300.01200.30
310.01090.28
320.00970.25
330.00860.22
340.00760.19
350.00670.17
360.00580.15

Data sources and version: see “Standards & Sources” below. Last updated 2025-11-25.

Practical guidance

  • Round inches to 4 decimals and mm to 2 decimals for spec sheets; keep more precision in CAD.
  • Coatings and galvanization add thickness; confirm with supplier tolerances for critical bends and fits.
  • For HVAC, enclosures, and panels, check rigidity and weight alongside thickness when selecting gauge.
  • Document the material and gauge system in drawings to avoid substituting a different chart.

Application scenarios — recommended gauges

  • HVAC ductwork: typical 26–24 ga (regional standards apply).
  • Enclosures and electrical cabinets: typical 16–18 ga (balance structural strength and weight).
  • Automotive body panels: typical 20–22 ga.
  • Decorative panels: typical 22–24 ga.

Notes

  • Weight and rigidity: consider panel size, reinforcement, and mounting.
  • Bend radius: check tooling and alloy; thin sheets may wrinkle, thick sheets may crack.
  • Coating impact: galvanization or paint adds thickness; confirm base sheet thickness separately.

Standards & Sources

Gauge numbers for sheet metal are table-driven and differ by material. Values shown are nominal and widely used for industry reference. Always verify with supplier datasheets and applicable specifications when tolerances matter.

Note: Galvanized thickness can include zinc coating; nominal gauge values are for base sheet and may vary by coating specification.

Frequently Asked Questions

Specify sheet thickness with confidence

Use the material-specific gauge charts, then cite both inches and millimeters on drawings to prevent fabrication surprises.

Open mm to inchesView chart
Sheet Metal Gauge to mm and inches — Thickness Conversion