Metal Sizing: Imperial vs Metric – Understanding the Differences

Metal Sizing: Imperial vs Metric – Understanding the Differences

When purchasing metal, it’s crucial to understand the difference between imperial and metric sizing. While the UK primarily uses metric measurements, many industries and suppliers still use imperial sizes, particularly for tubing, sheets, and bars.

Converting between the two can be confusing, but having a reference chart makes it easier to ensure you get the right size for your project.

We offer a wide range of aluminium, mild steel, stainless steel, and galvanised metals in various sizes. This guide will help you understand the key differences between imperial and metric sizing and provide a simple conversion chart for reference.

Understanding Imperial vs Metric Metal Sizing

  • Imperial measurements (inches, feet) are commonly used in the US and some UK industries, particularly in engineering and fabrication.
  • Metric measurements (millimetres, centimetres, metres) are the standard in Europe and most modern applications.

 

Converting between the two is straightforward, but precision is key, especially for machining or fitting applications.

Metric to Imperial Metal Sizing Chart

Below is a quick reference chart to help you convert between imperial and metric sizes for metal thickness, diameters, and dimensions.

Metric (mm) Imperial (inches – decimal) Imperial (inches – fraction)
0.5mm 0.020″ 1/50″
0.8mm 0.031″ 1/32″
1mm 0.039″ 1/25″
1.2mm 0.047″ 3/64″
1.5mm 0.059″ 1/16″
2mm 0.079″ 5/64″
2.5mm 0.098″ 3/32″
3mm 0.118″ 1/8″
3.5mm 0.138″ 9/64″
4mm 0.157″ 5/32″
5mm 0.197″ 13/64″
6mm 0.236″ 15/64″
8mm 0.315″ 5/16″
10mm 0.394″ 25/64″
12mm 0.472″ 15/32″
15mm 0.591″ 19/32″
16mm 0.630″ 5/8″
18mm 0.709″ 45/64″
20mm 0.787″ 25/32″
22mm 0.866″ 55/64″
25mm 0.984″ 1″
30mm 1.181″ 1-3/16″
32mm 1.260″ 1-1/4″
35mm 1.378″ 1-3/8″
38mm 1.496″ 1-1/2″
40mm 1.575″ 1-37/64″
45mm 1.772″ 1-3/4″
50mm 1.969″ 2″
60mm 2.362″ 2-3/8″
75mm 2.953″ 3″
80mm 3.150″ 3-5/32″
100mm 3.937″ 4″
120mm 4.724″ 4-23/32″
150mm 5.906″ 5-29/32″
200mm 7.874″ 7-7/8″
250mm 9.843″ 9-27/32″

How to Use This Chart

This chart provides a quick reference for converting metal thickness, bar diameters, and sheet sizes from metric to imperial measurements.

If you’re purchasing from Speciality Metals, our team can help you select the perfect size for your project.

Why Understanding Metal Sizing Matters

  • Precision: Ensures you order the exact size required for fabrication or construction.
  • Machining Compatibility: Helps when working with designs based on imperial or metric systems.
  • International Standards: Many industries work with both systems, so accurate conversions are essential.

At Speciality Metals, we offer a wide range of mild steel, stainless steel, aluminium, and galvanised metal products.

Whether you need round tubes, box sections, U channels, flat bars, or sheet metal, we provide high-quality materials cut to size.

Browse our full range here or contact us for expert guidance on selecting the right metal for your project!

As always, thank you for checking out our blog. We hope that this helps you with your project. 

Please also check out the other articles in our helpful guide series. We have written about aluminium sheeting and checker plate recently to name but two of our articles.

We are also proud to sell this product on our highly popular eBay store, check us out there too.

If you have any further questions, feel free to contact us.

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