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Sheet metal · U.S. Standard Gauge · USG

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

https://shopmath.org/gauges/us-standard/15 · data verified August 1, 2026

15 gauge U.S. Standard sheet is 0.0703 in thick — 1.786 mm. A square foot weighs 2.81 lb (13.73 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
15 ga
Material
U.S. Standard Gauge
Inch
0.0703
mm
1.786
System
USG

15 Gauge U.S. Standard · nominal thickness

0.0703 in

Millimetre
1.786mm
Weight
2.81lb/ft²
Weight
13.73kg/m²

Nominal thickness on the USG system. Gauge numbers are material-specific — "15 gauge" on its own does not name a thickness.

15 Gauge U.S. Standard Sheet Thickness

15 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.

15 Gauge U.S. Standard — thickness and weight
PropertyValue
Thickness, decimal inch0.0703 in
Thickness, millimetre1.786 mm
Weight per square foot2.81 lb/ft²
Weight per square metre13.73 kg/m²
Gauge systemUSG

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.

15 Gauge Thickness in Every Other Sheet Material

Gauge 15 spans 0.0571 in to 0.0710 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 15 gauge sheet across materials
PropertyPropertyThickness
MaterialGauge systeminmm
Sheet AluminiumB&S0.05711.450
Galvanized Steelgalvanized-MSG0.07101.803
Sheet SteelMSG0.06731.708
U.S. Standard GaugeUSG0.07031.786

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 15 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 15 gauge
PropertyThickness
Gaugeinmm
13 ga0.09382.381
14 ga0.07811.984
15 ga0.07031.786
16 ga0.06251.587
17 ga0.05631.429

Sources and Method for 15 Gauge U.S. Standard Thickness

15 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

  0.0703 × 41.82  =  2.81 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 15 Gauge U.S. Standard Reference

Citation

ShopMath. "15 Gauge U.S. Standard Thickness in Inches and Millimetres." ShopMath, verified August 1, 2026, https://shopmath.org/gauges/us-standard/15

BibTeX

@misc{shopmath-gauges-us-standard-15,
  title        = {15 Gauge U.S. Standard Thickness in Inches and Millimetres},
  author       = {{ShopMath}},
  year         = {2026},
  howpublished = {\url{https://shopmath.org/gauges/us-standard/15}},
  note         = {Data verified 2026-08-01}
}

Permanent URL

https://shopmath.org/gauges/us-standard/15

Common Questions About 15 Gauge U.S. Standard

How thick is 15 gauge U.S. Standard?

15 gauge U.S. Standard is 0.0703 in thick, which is 1.786 mm. A square foot weighs 2.81 lb (13.73 kg/m²).

What is 15 gauge U.S. Standard in mm?

1.786 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 15 gauge U.S. Standard thicker than 14 gauge?

No — a lower gauge number is thicker sheet. 14 gauge us standard is 0.0781 in (1.984 mm) against 0.0703 in (1.786 mm) for 15 gauge U.S. Standard, a difference of 0.0078 in.

Why is 15 gauge a different thickness in other materials?

Because each material is indexed on its own gauge system. At 15 gauge: Aluminium 0.0571 in (B&S), Galvanized 0.0710 in (galvanized-MSG), Steel 0.0673 in (MSG), US Standard 0.0703 in (USG). The number is a position in a series, not a thickness, so 3 other readings of "15 gauge" are all equally correct.

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