Bolt Size - Information and Online Shopping

Finding The Right Bolt
In order to determine the right bolt size for your particular project, you have to think
about the size of the threads. Too large a thread size will cause fasteners to loosen
and come apart. Too small a thread size will not be able to handle the stress being
applied to the fastener. We at are always here to answer any
questions you may have, but here is some useful information to help you further
understand the process.

Bolt Size: Follow the Thread
A thread is basically a continuous protruding or receding helical ridge formed along
the length of a cylinder. This ridge is referred to as the crest. The space between
each of the crests, or ridge components of a fastener is the root. The crest and ridge
of a bolt are set an angle, which is known as the helix angle.

Bolt sizes vary to accommodate differing major diameters. The major diameter is
measured by taking into account the outer diameter of the tops of the thread crests
on a bolt. These measurements are expressed in millimeters, and are usually
rounded off to the next highest whole number. For example, A 3.98mm bolt will be
referred to as a 4mm bolt. To make things simpler, bolt sizes are broken down into
the letter "M," followed by a number. An M5 bolt for example, is simply a bolt with a
five millimeter major diameter.

The concept of threads and bolt size isn't too difficult once you get the hang of it.
What can be difficult is determining what sizes are best for your particular project. It's
important to look at the ksi rating of a bolt. Ksi stands for 1000 pounds per square
inch. If you have any questions about what kind of bolts to buy from us here at, feel free to write or call anytime. We're here to make bolt size
shopping easy and convenient.
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