The unthreaded portion of a headed bolt is called the grip. The length of all headed bolts (except countersunk head bolts) are measured from underneath the head to the end of the threads. The overall bolt length is made up of thread length plus grip length.
What is a typical tolerance on the Shank Length (G) for a bolt?
@Ron- The shank length will vary a bit depending on the manufacturer and is not a black and white answer. ASME B18.21.1 which covers hex bolt dimensions, allows for up to 5 full coarse threads to extend into the grip length, so therefore the grip/thread length will vary depending on the diameter of the bolt, since five threads of 1/2-13 and five threads of 1-1/2-6 will take up different amounts of space. Additionally, many of the longer imported sizes, like those 10″ long and longer, are now being manufactured with 6″ of thread regardless. If the grip length is critical you might contact either us or your normal bolt supplier and check with them as to what they have available currently.