What is the difference between coarse and fine threads?

• A. Coarse has more threads per inch (smaller pitch); fine has fewer threads per inch (larger pitch)
• B. Coarse has fewer threads per inch (larger pitch); fine has more threads per inch (smaller pitch)
• C. They differ only in thread color
• D. They have the same pitch but different thread angles

Answer: (B)

The key idea is pitch—the distance between one thread and the next. Coarse threads have fewer threads per inch, so the pitch is larger. Fine threads have more threads per inch, giving a smaller pitch.

This difference changes how they behave in use. Coarse threads bite into softer materials more easily, cut faster, and tolerate dirt, misalignment, or damage better, making them a good choice for quick, rough assembly. Fine threads give you more precise adjustment and more engagement per turn, which can improve holding power in tight or thin-walled parts and can resist loosening in some situations.

Color or thread angle isn’t what distinguishes them. The main difference is the spacing of the threads—pitch.