Which measurement does a pitch gauge help determine on a fastener?

• A. Bolt length
• B. Threads per inch
• C. Outer diameter
• D. Pitch angle

Answer: (B)

A pitch gauge is used to identify how tightly the threads are spaced along the fastener, which is the thread pitch expressed as threads per inch. You match the gauge blades to the threads and the blade that fits best tells you how many threads occur in one inch, i.e., the TPI. It doesn’t measure bolt length (that’s a linear distance), outer diameter (that needs calipers or a micrometer), or a pitch angle (not a standard measurement for fasteners). So the measurement most directly determined by a pitch gauge is the number of threads per inch.