Bolt diameter (nominal diameter)

The bolt diameter d corresponds to the outer diameter of the thread, and is also called the nominal diameter.

This diameter is also used to specify the bolt size; i.e., a bolt with d=12mm is an M12. Typically, bolt diameters cannot be freely selected. They are standardized and must be taken from the corresponding standard.

For example, only the following diameters d can be selected from the bolt standard DIN EN ISO 4017:2015 for hexagonal screws without shank:

1.6, 2, 2.5, 3, 4, 5, 6, 8, 10, 12, 16, 20, 24, 30, 36, 42, 48, 56, 64

other possible threads that should be avoided are

3.5, 14, 18, 22, 27, 33, 39, 45, 52, 60