MARSHALLSTEELPTY LTD
Family-owned steel · Burleigh Heads
www.marshallsteel.com.au
07 5576 6037
mm ↔ Inches Steel Size Chart
Quick metric / imperial conversions for the most common steel sizes.
Hand this on the workshop wall. Standard mm sizes stocked at Burleigh Heads and the closest imperial equivalents.
| Millimetres | Inches (approx.) | Common use |
|---|---|---|
| 6mm | 1/4″ | Thin flat bar, small bolts |
| 8mm | 5/16″ | Thin flat bar, small bolts |
| 10mm | 3/8″ | Thin flat bar, small bolts |
| 12mm | 1/2″ | Brackets, balusters, small frames |
| 16mm | 5/8″ | Brackets, balusters, small frames |
| 19mm | 3/4″ | Brackets, balusters, small frames |
| 20mm | ≈ 13/16″ | Brackets, balusters, small frames |
| 25mm | 1″ | Brackets, balusters, small frames |
| 32mm | 1 1/4″ | Gates, light framing, posts |
| 40mm | 1 9/16″ | Gates, light framing, posts |
| 50mm | 2″ | Gates, light framing, posts |
| 65mm | 2 9/16″ | Patios, sheds, columns |
| 75mm | ≈ 3″ | Patios, sheds, columns |
| 89mm | 3 1/2″ | Patios, sheds, columns |
| 100mm | ≈ 4″ | Patios, sheds, columns |
| 125mm | ≈ 5″ | Beams, structural posts |
| 150mm | ≈ 6″ | Beams, structural posts |
| 200mm | ≈ 8″ | Heavy structural, commercial |
| 250mm | ≈ 10″ | Heavy structural, commercial |
| 300mm | ≈ 12″ | Heavy structural, commercial |
Conversions are nominal — imperial sizes were never exact metric. Use this as a shop reference, not for engineering tolerances.