Carriage bolts are available in a wide range of sizes, ideal for many different applications. Coach bolt sizes can be recorded in either metric or imperial measurements, so it is important to select the most suitable carriage bolt size for your specific requirements. Additionally, the sizes can refer to several different measurements with these parts, including bolt length and thread size, so you must carefully select the best coach bolt for the task at hand.
Carriage Bolt Thread Size
Coach bolts are typically measured in metric threads using the international standard ISO metric thread size system. Each bolt is measured and given a size which is denoted by a number preceded by the letter ‘M’. The outer diameter of the thread (measured in millimetres) is indicated by the number in the system. For instance, a coach bolt with a thread size of M6 would have a 6mm thread diameter.
Once again, care should be taken not to confuse carriage bolts with coach screws as the two are different parts despite their similar name and head shape. As a rough guide, coach screws are typically measured in millimetres rather than simply using the ISO metric system alone.
Browse some of the most popular coach bolt thread sizes below: