# How to Identify Metric Bolts

Written by mark kennan
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Some, but not all, metric bolts are identified with an "M" at the start of the bolt sizing information, such as "M8 x 1.5 x 18" but others simply list the measurements. The measurements are expressed in millimetres. American bolts list threads per inch; metric lists the distance between threads. Metric bolts are incompatible with American bolts.

Skill level:
Easy

## Instructions

1. 1

Use the first number in the measurement to identify the diameter of the bolt. For example, if the metric bolt is M13x1.7x20, it would have a diameter of 13 millimetres.

2. 2

Use the second number in the measurement to identify the thread distance. For example, if the metric bolt is M13x1.7x20, it would have a thread distance of 1.7 millimetres.

3. 3

Use the third number in the measurement to identify the bolt length. For example, if the metric bolt is M13x1.7x20, it would have a length of 20 millimetres.

4. 4

Use the number on the head of the bolt to determine the bolt strength. Not all bolts will have a marking but the higher the number the stronger the bolt.

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