The Difference Between Metric Thread, American Thread And Imperial Thread

“Metric thread,” “American thread,” and “imperial thread” are terms used to describe different systems of thread standards for fasteners, such as screws and bolts. These standards govern the size, pitch (spacing between threads), and other characteristics of threaded fasteners. Let’s explore the differences between these three thread standards.

Metric Thread:

The metric thread system is based on the metric system of measurement, which uses millimeters (mm) as its primary unit.

Thread dimensions are expressed in millimeters, such as thread diameter and pitch.

The thread pitch is the distance between adjacent threads and is expressed as the number of threads per unit length (e.g., threads per mm).

The most common metric thread standard is the ISO metric thread, which is used internationally.

Metric threads are generally considered more precise and standardized, making them a popular choice in industries that prioritize accuracy and interchangeability.

American Thread:

The term “American thread” is a bit ambiguous because the United States uses various thread standards. However, one of the most well-known American thread standards is the Unified Thread Standard (UTS), which includes the Unified National Thread and the Unified Fine Thread.

The Unified National Thread (UNC) has a coarse thread pitch, while the Unified Fine Thread (UNF) has a finer thread pitch.

American threads are often expressed in inches, and their dimensions are based on a combination of fractional inches and the number of threads per inch.

American thread standards were historically more prevalent in the United States but have been largely replaced by metric threads in many modern applications.

Imperial Thread:

The term “imperial thread” is sometimes used interchangeably with “American thread,” but it can also refer to older British thread standards that predate metrication.

Imperial threads are expressed in inches, similar to American threads, and may include standards like British Standard Whitworth (BSW) and British Standard Fine (BSF).

These standards were widely used in the UK and some other parts of the British Empire.

In summary, “metric thread” refers to threads based on the metric system of measurement, “American thread” often refers to threads based on the Unified Thread Standard in the United States, and “imperial thread” can refer to both American threads and older British thread standards. The choice of thread standard depends on factors such as the application, industry standards, and regional practices.

Xinchi Fastener Company is a trustworthy fastener company, especially in furniture nuts. And we are the designated fastener supplier to“STAPLE”. As a trusted fastener supplier,  Xinchi Fastener Company can offer a wide range of high-quality fasteners, including T nuts, screws, bolts, rivets, washers, etc. If you want to know more about fasteners or want to wholesale fasteners, please feel free to contact us. And then our experienced and expert service team will reply to you as soon as possible.