How thick is 38 gauge U.S. Standard?

38 gauge U.S. Standard is 0.0063 in thick, which is 0.159 mm. A square foot weighs 0.25 lb (1.22 kg/m²).

What is 38 gauge U.S. Standard in mm?

0.159 mm. The gauge number is an index into the USG system rather than a measurement, so it converts to a fixed thickness rather than a round metric figure.

Is 38 gauge U.S. Standard thicker than 37 gauge?

No — a lower gauge number is thicker sheet. 37 gauge us standard is 0.0066 in (0.169 mm) against 0.0063 in (0.159 mm) for 38 gauge U.S. Standard, a difference of 0.0003 in.

Sheet metal · U.S. Standard Gauge · USG

38 Gauge U.S. Standard Thickness in Inches and Millimetres

https://shopmath.org/gauges/us-standard/38 · data verified August 1, 2026

38 gauge U.S. Standard sheet is 0.0063 in thick — 0.159 mm. A square foot weighs 0.25 lb (1.22 kg/m²). The gauge number indexes the USG system, so the same number is a different thickness in another material — the comparison is below. Thicknesses are nominal, before mill tolerance.

Gauge: 38 ga
Material: U.S. Standard Gauge
Inch: 0.0063
mm: 0.159
System: USG

38 Gauge U.S. Standard · nominal thickness

0.0063 in

Millimetre: 0.159mm
Weight: 0.25lb/ft²
Weight: 1.22kg/m²

Nominal thickness on the USG system. Gauge numbers are material-specific — "38 gauge" on its own does not name a thickness.

38 Gauge U.S. Standard Sheet Thickness

38 Gauge U.S. Standard is defined by the 15 U.S.C. 206 (wrought iron basis), not by a measurement — the gauge number is an index into that system, which is why the same number means a different thickness in another material.

38 Gauge U.S. Standard — thickness and weight
Property	Value
Thickness, decimal inch	0.0063 in
Thickness, millimetre	0.159 mm
Weight per square foot	0.25 lb/ft²
Weight per square metre	1.22 kg/m²
Gauge system	USG

Nominal thickness. Mill tolerance on sheet is typically a few thousandths of an inch either way and varies with width and process; measure the stock when the fit matters.

Gauges Either Side of 38 Gauge U.S. Standard

A higher gauge number is thinner sheet. The steps are not equal — the gauge systems are geometric, so the difference between two gauges shrinks as the sheet gets thinner.

U.S. Standard Gauge gauges adjacent to 38 gauge
Property	Thickness
Gauge	in	mm
36 ga	0.0070	0.179
37 ga	0.0066	0.169
38 ga	0.0063	0.159

Sources and Method for 38 Gauge U.S. Standard Thickness

38 Gauge U.S. Standard thicknesscomputed

15 U.S.C. 206 (Act of Mar. 3, 1893, ch. 221, 27 Stat. 746) — U.S. Standard Gauge for sheet and plate iron and steel; 15 U.S.C. 206 statutory weights; MSG (41.82 lb/ft2 per inch), galvanized zinc allowance, and Brown & Sharpe formula per docs/research/data-sourcing.md §3.7

Verified against Wikipedia Sheet metal, Standard sheet metal gauges table (CC BY-SA 4.0) — 137/137 checks passed at 0.05 mil

Computed from the standard's formulas, then checked against published tables.

Formula

Weight per square foot, sheet steel

lb/ft²  =  thickness (in) × 41.82

  0.0063 × 41.82  =  0.25 lb/ft²

41.82 lb/ft² per inch of thickness is the Manufacturers' Standard Gauge basis for steel. The U.S. Standard Gauge of 1893 uses a wrought-iron basis of 40 lb/ft² per inch, which is why the two systems differ.

Assumptions

Thicknesses are nominal. Mill tolerance varies with width, process and material and is not part of the gauge definition.
Gauge is an index into a material-specific system, not a unit. A gauge number without a material is ambiguous by construction.
Dataset scope: EXCLUDED: stainless steel (genuinely ambiguous convention, only one source in hand), zinc, copper, brass, steel tube wall.

Data last verified

August 1, 2026

How this data is built and checked →

How to Cite This 38 Gauge U.S. Standard Reference

Citation

ShopMath. "38 Gauge U.S. Standard Thickness in Inches and Millimetres." ShopMath, verified August 1, 2026, https://shopmath.org/gauges/us-standard/38

BibTeX

@misc{shopmath-gauges-us-standard-38,
  title        = {38 Gauge U.S. Standard Thickness in Inches and Millimetres},
  author       = {{ShopMath}},
  year         = {2026},
  howpublished = {\url{https://shopmath.org/gauges/us-standard/38}},
  note         = {Data verified 2026-08-01}
}

Permanent URL

https://shopmath.org/gauges/us-standard/38

Common Questions About 38 Gauge U.S. Standard

How thick is 38 gauge U.S. Standard?: 38 gauge U.S. Standard is 0.0063 in thick, which is 0.159 mm. A square foot weighs 0.25 lb (1.22 kg/m²).
What is 38 gauge U.S. Standard in mm?: 0.159 mm. The gauge number is an index into the USG system rather than a measurement, so it converts to a fixed thickness rather than a round metric figure.
Is 38 gauge U.S. Standard thicker than 37 gauge?: No — a lower gauge number is thicker sheet. 37 gauge us standard is 0.0066 in (0.169 mm) against 0.0063 in (0.159 mm) for 38 gauge U.S. Standard, a difference of 0.0003 in.

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