---
type: "sheet-metal-gauge"
gauge_number: "9"
material: "us-standard"
material_name: "U.S. Standard Gauge"
gauge_system: "USG"
thickness_in: 0.1563
thickness_mm: 3.9688
weight_lb_per_sqft: 6.25
weight_kg_per_sqm: 30.52
standard: "15 U.S.C. 206; Manufacturers' Standard Gauge; Brown & Sharpe / AWG"
verified: "August 1, 2026"
url: https://shopmath.org/gauges/us-standard/9
---

# 9 Gauge U.S. Standard Gauge — Sheet Metal Thickness in Inches and Millimetres

9 gauge us standard is 0.1563 in (3.969 mm) thick. That figure is on the USG — gauge is a material-specific numbering scheme, not a unit, so the same number is a different thickness in another material.

- **Gauge**: 9
- **Material**: U.S. Standard Gauge
- **Gauge system**: USG
- **Thickness**: 0.1563 in (3.969 mm)
- **Weight**: 6.250 lb/ft² (30.52 kg/m²)

## 9 Gauge U.S. Standard Gauge Thickness

| Property | Value |
| --- | --- |
| Thickness (in) | 0.1563 |
| Thickness (mm) | 3.969 |
| Weight (lb/ft²) | 6.250 |
| Weight (kg/m²) | 30.52 |
| Gauge system | USG |

## 9 Gauge Across Materials

The same gauge number in every material this reference covers. They differ because each material carries its own gauge system, not because one chart is wrong.

| Material | Gauge system | Thickness (in) | Thickness (mm) | lb/ft² | kg/m² |
| --- | --- | --- | --- | --- | --- |
| [Sheet Aluminium](https://shopmath.org/gauges/aluminum/9.md) | B&S | 0.1144 | 2.906 |  |  |
| [Galvanized Steel](https://shopmath.org/gauges/galvanized/9.md) | galvanized-MSG | 0.1532 | 3.891 | 6.250 | 30.52 |
| [Sheet Steel](https://shopmath.org/gauges/steel/9.md) | MSG | 0.1495 | 3.796 | 6.250 | 30.52 |
| U.S. Standard Gauge (this page) | USG | 0.1563 | 3.969 | 6.250 | 30.52 |

## Sources and Method for 9 Gauge U.S. Standard Gauge

### U.S. Standard Gauge gauge thicknesses

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

### Assumptions

- Gauge is a numbering scheme, not a unit. A thickness is only meaningful with its material and gauge system stated.
- Sheet is supplied to a mill tolerance around these nominal thicknesses; measure the stock when the fit matters.
- 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

## Common Questions About 9 Gauge U.S. Standard Gauge

### How thick is 9 gauge us standard?

9 gauge us standard is 0.1563 in (3.969 mm) thick, on the USG.

### What is 9 gauge in mm?

9 gauge us standard is 3.969 mm. Gauge is not a unit — the same number means a different thickness in a different material, so the material has to be stated with it.

### Is 9 gauge the same thickness in every material?

No. 9 gauge is 0.1563 in in u.s. standard gauge, but 0.1144 in in sheet aluminium, 0.1532 in in galvanized steel, 0.1495 in in sheet steel. Each material uses its own gauge system: B&S; galvanized-MSG; MSG; USG.

### How much does 9 gauge us standard weigh per square foot?

6.250 lb per square foot (30.52 kg per square metre).

## Related pages

- Thicker (lower gauge number): [8 gauge u.s. standard gauge](https://shopmath.org/gauges/us-standard/8.md) — 0.1719 in
- Thinner (higher gauge number): [10 gauge u.s. standard gauge](https://shopmath.org/gauges/us-standard/10.md) — 0.1406 in
- All u.s. standard gauge gauges: [U.S. Standard Gauge gauge chart](https://shopmath.org/gauges/us-standard.md)
- All materials and gauges: [Sheet metal gauge reference](https://shopmath.org/gauges.md)
- Full cross-material chart: [Sheet metal gauge chart](https://shopmath.org/charts/sheet-metal-gauge.md)

---

*Source: [ShopMath](https://shopmath.org/gauges/us-standard/9) — data verified August 1, 2026. Reference data; verify against the governing standard before manufacture.*