In thread terminology, which diameter is the largest for a Unified thread?

In thread terminology, which diameter is the largest for a Unified thread?

• A. Major diameter
• B. Pitch diameter
• C. Smallest diameter
• D. Thread length

Answer: (A)

The largest diameter in a Unified thread is the major diameter. It’s measured across the crests of the threads—the outermost width of the thread profile. This dimension defines the overall external size of the thread, like the bolt’s outer diameter. The minor diameter is the smallest diameter at the thread roots, and the pitch diameter is the middle diameter where the thickness of the thread equals the thickness of the gap. Thread length isn’t a diameter at all. So the major diameter is the largest dimension of the thread.

The largest diameter in a Unified thread is the major diameter. It’s measured across the crests of the threads—the outermost width of the thread profile. This dimension defines the overall external size of the thread, like the bolt’s outer diameter. The minor diameter is the smallest diameter at the thread roots, and the pitch diameter is the middle diameter where the thickness of the thread equals the thickness of the gap. Thread length isn’t a diameter at all. So the major diameter is the largest dimension of the thread.