Measuring Fastener Length

Fastener length is generally measured from the point where the surface of the material will be when the fastener is installed to the end of the fastener. Thus, fasteners with heads that sit above the surface are measured from under the head to the end of the fastener, while fasteners that sit flush with the surface are measured from the top of the head to the end of the fastener.

Head Above Surface	Countersunk Head	Oval Head

There are some 'oddball' fasteners like U-bolts, hanger bolts, and shoulder bolts where length is measured differently. Throughout our catalog you will find detailed drawings indicating where measurements are taken when selecting a fastener.