Avon Stainless Marine

Tel: +44 (0) 117 972 8560
Fax: +44 (0) 117 972 8570
info@avonstainlessfasteners.co.uk

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How to measure a screw/bolt

Fastener length is measured from where the material surface is assumed to be, to the end of the fastener.

Head sits above surface

 

For fasteners where the head usually sits above the surface, the measurement is from directly under the head to the end of the fastener.

Countersunk

For fasteners that are designed to be countersunk, the measurement is made from the point on the head where the surface of the material is, to the end of the fastener.


Carriage Bolts

Carriage bolts are measured from directly under the head.

Carriage Bolts


Eye Bolts

Eye Bolts are measured from under the eye.

Eye BoltsEye Bolts Eye BoltsEye Bolts


Hanger Bolts

Hanger bolt length is measured from end to end.

Hanger Bolts


Hex Bolts

Hex bolts are measured from under the head to the tip of the bolt.

Hex Bolts


Lag Bolts (Lag Screws)

Lag Bolts are measured from under the head.

Lag Bolts (Lag Screws)


Machine Screws

Machine screw measurement depends on the style of head it has.

  • Countersunk (Flat or Oval head) is measured overall.

Flat Countersunk Machine Screws Oval Countersunk Machine Screws

  • Pan Head or Round Head screws are measured from under the head.

Pan head Machine Screws Round head screws


Sex Bolts

Sex bolt length is measured from under the head.

Sex Bolts


Sheet Metal Screws

Sheet metal screw measurement depends upon the type of screw you are using.

  • Countersunk screws (Flat or Oval head) are measured by overall length.

Flat Countersunk Sheet Metal Screws Oval Countersunk Sheet Metal Screws

  • Pan Head, Truss Head, and Hex Head screws are measured from under the head.

Pan Head Sheet Metalscrews Hex Head Sheet Metal screws


Shoulder Bolts

Shoulder bolt length is measured as the length of the shoulder.

Shoulder Bolts

 


Socket Products

Socket screw measurement depends upon the type of screw you are using.

  • Flat Socket Caps are measured by the overall length.

Flat Socket Caps

  • Socket Head Caps and Button Head Caps are measured from under the head.

Socket Head CapsButton Head Caps


Wood Screws

Wood screw measurement depends upon the type of screw you are using.

  • Countersunk (Flat or Oval head) are measured overall.

Countersunk (Flat head)Countersunk (Oval head) Wood Screws

  • Round head screws are measured from under the head.

Round head screws