# Imperial and metric

By telleropnul, April 27, 2019

Common imperial sizes in mm:

1 inch = 25.4mm

1/2 inch = 12.5mm

1/4 inch = 6.35mm

1/8 inch = 3.17mm

### Fasteners (bolts/nuts)

This table may be used to find the nearest matching bolt / nut sizes in either imperial or metric.

### Sheet metal

https://en.wikipedia.org/wiki/Sheet_metal#Gauge

### American Wire Gauge (AWG)

I’m not even going to attempt to explain:

https://en.wikipedia.org/wiki/American_wire_gauge#Tables_of_AWG_wire_sizes

### Lumber sizes

2x4s are not actually 2 inches by 4 inches. When the board is first rough sawn from the log, it is a true 2×4, but the drying process and planing of the board reduce it to the finished 1.5×3.5 size. Here are the common sizes of lumber, and their actual sizes.

Nominal |
Actual |
Actual – Metric |

1″ x 2″ |
3/4″ x 1-1/2″ |
19 x 38 mm |

1″ x 3″ |
3/4″ x 2-1/2″ |
19 x 64 mm |

1″ x 4″ |
3/4″ x 3-1/2″ |
19 x 89 mm |

1″ x 5″ |
3/4″ x 4-1/2″ |
19 x 114 mm |

1″ x 6″ |
3/4″ x 5-1/2″ |
19 x 140 mm |

1″ x 7″ |
3/4″ x 6-1/4″ |
19 x 159 mm |

1″ x 8″ |
3/4″ x 7-1/4″ |
19 x 184 mm |

1″ x 10″ |
3/4″ x 9-1/4″ |
19 x 235 mm |

1″ x 12″ |
3/4″ x 11-1/4″ |
19 x 286 mm |

1-1/4″ x 4″ |
1″ x 3-1/2″ |
25 x 89 mm |

1-1/4″ x 6″ |
1″ x 5-1/2″ |
25 x 140 mm |

1-1/4″ x 8″ |
1″ x 7-1/4″ |
25 x 184 mm |

1-1/4″ x 10″ |
1″ x 9-1/4″ |
25 x 235 mm |

1-1/4″ x 12″ |
1″ x 11-1/4″ |
25 x 286 mm |

1-1/2″ x 4″ |
1-1/4″ x 3-1/2″ |
32 x 89 mm |

1-1/2″ x 6″ |
1-1/4″ x 5-1/2″ |
32 x 140 mm |

1-1/2″ x 8″ |
1-1/4″ x 7-1/4″ |
32 x 184 mm |

1-1/2″ x 10″ |
1-1/4″ x 9-1/4″ |
32 x 235 mm |

1-1/2″ x 12″ |
1-1/4″ x 11-1/4″ |
32 x 286 mm |

2″ x 2″ |
1-1/2″ x 1-1/2″ |
38 x 38 mm |

2″ x 4″ |
1-1/2″ x 3-1/2″ |
38 x 89 mm |

2″ x 6″ |
1-1/2″ x 5-1/2″ |
38 x 140 mm |

2″ x 8″ |
1-1/2″ x 7-1/4″ |
38 x 184 mm |

2″ x 10″ |
1-1/2″ x 9-1/4″ |
38 x 235 mm |

2″ x 12″ |
1-1/2″ x 11-1/4″ |
38 x 286 mm |

3″ x 6″ |
2-1/2″ x 5-1/2″ |
64 x 140 mm |

4″ x 4″ |
3-1/2″ x 3-1/2″ |
89 x 89 mm |

4″ x 6″ |
3-1/2″ x 5-1/2″ |
89 x 140 mm |

When you visit your local hardware shop:

1×4 = 19mm x 90mm

1×5 = 19mm x 120mm

1×6 = 19mm x 140mm

1×8 = 19mm x 190mm

1×10 = 19mm x 240mm

2×4 = 35mm x 90mm

2×5 = 35mm x 120mm

2×6 = 35mm x 140mm

2×8 = 35mm x 190mm

2×10 = 35mm x 240mm