How to Identify Fasteners: Thread Pitch and Thread Count

Thread pitch and thread count are important parts of measuring fastener size. Both thread pitch and thread count are used to indicate the fineness of the thread.

Thread pitch and thread count is only important for machine thread fasteners, which take a nut or thread into a tapped hole. I’ll explain each concept below.

Thread Count (TPI)

Thread count is measured using Threads Per Inch (TPI). This indicates the number of threads in a one inch space along the fastener. Most American fasteners use TPI for thread count measurements, while the rest of the world uses the metric thread pitch measurement.

Thread Pitch

Metric fasteners use thread pitch instead of thread count. Thread pitch indicates the distance between threads measured in millimeters along the length of the fastener. If a fastener has a thread pitch of 2, it means that there are 2 millimeters between one thread and the next. In most cases, smaller fasteners have a finer thread, which means they have a lower thread pitch.

How to measure thread count and thread pitch

Fortunately, you don’t necessarily have to break out the measuring tape in order to check thread pitch and thread count. Instead, simply use a thread gauge. Thread gauges are designed to make repeated thread pitch and thread count measurements easier. If you’re going to be measuring multiple fasteners, buying a thread gauge can save a considerable amount of time.

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