Resources / Reference
Gauge & Weight Reference
Aluminum sheet and coil use the Brown & Sharpe (B&S) gauge system, a different standard than steel gauge. Below is a B&S conversion table plus the formulas for calculating coil weight and length.
| B&S Gauge | Inches | Millimeters |
|---|---|---|
| 7 | 0.1443" | 3.665 mm |
| 8 | 0.1285" | 3.264 mm |
| 10 | 0.1019" | 2.588 mm |
| 12 | 0.0808" | 2.053 mm |
| 14 | 0.0641" | 1.628 mm |
| 16 | 0.0508" | 1.291 mm |
| 18 | 0.0403" | 1.024 mm |
| 20 | 0.0320" | 0.813 mm |
| 22 | 0.0253" | 0.643 mm |
| 24 | 0.0201" | 0.511 mm |
| 26 | 0.0159" | 0.405 mm |
| 28 | 0.0126" | 0.321 mm |
| 30 | 0.0100" | 0.255 mm |
Aluminum sheet and coil use the Brown & Sharpe (B&S) gauge system, which is different from the Manufacturers' Standard Gauge used for steel. Always specify B&S gauge or a direct thickness in mm/inches when ordering aluminum to avoid confusion. Figures are standard published B&S values, not Primealux Alloys measurements.
Coil weight formula
Weight (kg) = Length (m) × Width (m) × Thickness (m) × 2,700
Example: a 500 m length of 0.5 mm (0.0005 m) coil, 1.2 m wide: 500 × 1.2 × 0.0005 × 2,700 = 810 kg.
Coil length formula
Length ≈ π × (OD² − ID²) ÷ (4 × Thickness), all in consistent units
A theoretical estimate: actual length varies slightly with winding tightness.
Prefer not to do the math by hand? Use the coil weight & length calculator.
Frequently asked questions
- Is aluminum gauge the same as steel gauge?
- No. Aluminum uses the Brown & Sharpe (B&S) gauge system, while steel and galvanized sheet use the Manufacturers' Standard Gauge (MSG). The same gauge number means a different thickness in each system, so always specify B&S gauge or a direct thickness measurement when ordering aluminum.
- How do I calculate the weight of a coil?
- Weight equals length times width times thickness times density. For aluminum at 2,700 kg per cubic meter, a coil's weight in kilograms is length (m) times width (m) times thickness (m) times 2,700. See the worked example above.
- How do I estimate coil length from outer and inner diameter?
- Length is approximately pi times (OD squared minus ID squared), divided by four times the thickness, all in consistent units. It's a theoretical figure. Actual length varies slightly with winding tightness, so treat it as an estimate rather than an exact count.
- Why does coated coil come in a narrower width than mill-finish?
- That's not a gauge or weight question but a common follow-up: coated coil tops out at 1350 mm versus 1650 mm mill-finish, because the coating line itself sets the maximum width it can process. See the prepainted coil page for detail.