How to calculate the length of bolts and screws? Different bolts and screws are different. The following figure is an example. The L in the figure represents the length of the bolt.
Hexagonal bolts
Hexagon socket bolts
Pan head screws
Countersunk head screws
Semi-countersunk head screws
From the above diagram, we can know that the bolt length is not always the length of the entire bolt (including the head). The calculation of countersunk and semi-countersunk bolts includes the head. The following diagram is used to illustrate and is also convenient for everyone to remember:(文章来源：iMechanics机械)
