Major Diameter
Definition
The largest diameter of a screw thread, measured at the crest (top) of the external thread or the root of the internal thread. This is the nominal size of the screw (e.g., a #6 screw has 0.138" major diameter).
Practical Note
Major diameter determines the nominal screw size. For bolts, this is the shank diameter. Clearance holes must be larger than major diameter for the fastener to pass through.
Related Calculators
Interactive screw size reference. Look up major diameter, minor diameter, thread pitch, tap drill size, and clearance hole for machine screws in UNC, UNF, and metric standards.
Interactive bolt size reference. Look up head dimensions, thread specifications, recommended hole sizes, and matching nut dimensions for hex bolts in SAE and metric standards.
Calculate bolt torque, preload force, and clamping force for threaded fasteners. Supports metric and imperial threads.