How thick is 13 gauge U.S. Standard?

13 gauge U.S. Standard is 0.0938 in thick, which is 2.381 mm. A square foot weighs 3.75 lb (18.31 kg/m²).

What is 13 gauge U.S. Standard in mm?

2.381 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 13 gauge U.S. Standard thicker than 12 gauge?

No — a lower gauge number is thicker sheet. 12 gauge us standard is 0.1094 in (2.778 mm) against 0.0938 in (2.381 mm) for 13 gauge U.S. Standard, a difference of 0.0156 in.

Why is 13 gauge a different thickness in other materials?

Because each material is indexed on its own gauge system. At 13 gauge: Aluminium 0.0720 in (B&S), Galvanized 0.0934 in (galvanized-MSG), Steel 0.0897 in (MSG), US Standard 0.0938 in (USG). The number is a position in a series, not a thickness, so 3 other readings of "13 gauge" are all equally correct.

Sheet metal · U.S. Standard Gauge · USG

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

https://shopmath.org/gauges/us-standard/13 · data verified August 1, 2026

13 gauge U.S. Standard sheet is 0.0938 in thick — 2.381 mm. A square foot weighs 3.75 lb (18.31 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: 13 ga
Material: U.S. Standard Gauge
Inch: 0.0938
mm: 2.381
System: USG

13 Gauge U.S. Standard · nominal thickness

0.0938 in

Millimetre: 2.381mm
Weight: 3.75lb/ft²
Weight: 18.31kg/m²

Nominal thickness on the USG system. Gauge numbers are material-specific — "13 gauge" on its own does not name a thickness.

13 Gauge U.S. Standard Sheet Thickness

13 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.

13 Gauge U.S. Standard — thickness and weight
Property	Value
Thickness, decimal inch	0.0938 in
Thickness, millimetre	2.381 mm
Weight per square foot	3.75 lb/ft²
Weight per square metre	18.31 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.

13 Gauge Thickness in Every Other Sheet Material

Gauge 13 spans 0.0720 in to 0.0938 in depending on the material, because each material is indexed on a different gauge system. Ordering sheet by gauge without naming the material is how the wrong thickness arrives.

Thickness of 13 gauge sheet across materials
Property	Property	Thickness
Material	Gauge system	in	mm
Sheet Aluminium	B&S	0.0720	1.828
Galvanized Steel	galvanized-MSG	0.0934	2.373
Sheet Steel	MSG	0.0897	2.278
U.S. Standard Gauge	USG	0.0938	2.381

Steel uses the Manufacturers' Standard Gauge, galvanised adds a zinc-coating allowance to the steel thickness, aluminium and other non-ferrous sheet use the Brown & Sharpe geometric series, and U.S. Standard is the 1893 statute on a wrought-iron basis.

Gauges Either Side of 13 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 13 gauge
Property	Thickness
Gauge	in	mm
11 ga	0.1250	3.175
12 ga	0.1094	2.778
13 ga	0.0938	2.381
14 ga	0.0781	1.984
15 ga	0.0703	1.786

Sources and Method for 13 Gauge U.S. Standard Thickness

13 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

  0.0938 × 41.82  =  3.75 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 13 Gauge U.S. Standard Reference

Citation

ShopMath. "13 Gauge U.S. Standard Thickness in Inches and Millimetres." ShopMath, verified August 1, 2026, https://shopmath.org/gauges/us-standard/13

BibTeX

@misc{shopmath-gauges-us-standard-13,
  title        = {13 Gauge U.S. Standard Thickness in Inches and Millimetres},
  author       = {{ShopMath}},
  year         = {2026},
  howpublished = {\url{https://shopmath.org/gauges/us-standard/13}},
  note         = {Data verified 2026-08-01}
}

Permanent URL

https://shopmath.org/gauges/us-standard/13

Common Questions About 13 Gauge U.S. Standard

How thick is 13 gauge U.S. Standard?: 13 gauge U.S. Standard is 0.0938 in thick, which is 2.381 mm. A square foot weighs 3.75 lb (18.31 kg/m²).
What is 13 gauge U.S. Standard in mm?: 2.381 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 13 gauge U.S. Standard thicker than 12 gauge?: No — a lower gauge number is thicker sheet. 12 gauge us standard is 0.1094 in (2.778 mm) against 0.0938 in (2.381 mm) for 13 gauge U.S. Standard, a difference of 0.0156 in.
Why is 13 gauge a different thickness in other materials?: Because each material is indexed on its own gauge system. At 13 gauge: Aluminium 0.0720 in (B&S), Galvanized 0.0934 in (galvanized-MSG), Steel 0.0897 in (MSG), US Standard 0.0938 in (USG). The number is a position in a series, not a thickness, so 3 other readings of "13 gauge" are all equally correct.

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