While everyone can visually identify different types of screws, nuts, bolts and washers, we're not entirely sure about the different types that exist and what they're called. The language of screws is an easy one once you understand how exactly screws are classified. With this knowledge, ordering these small items from time to time, will be as easy as it can get.

Head types


Types of Screw head shapes can be classified as:

  • Flat
  • Pan
  • Oval
  • Round
  • Drywall
  • Hex washer (a flat washer that extends beyond the sides)

You would have definitely seen or used these screws sometime during your work or when you've fixed a home or office task chair.

Thread types


Based on thread types, screws can be classified into:

  • Sheet metal, which are zinc plated and have extremely sharp points
  • Sharp point drywall; drywall screws can be sharp point or self-drilling
  • Machine screws, which are available in different head shapes and drive styles.
  • Masonry screws penetrate masonry – brick, concrete or hollow block, and are typically used for wall partition brackets, electrical junction boxes and awning brackets.
  • Wood screws that are commonly used for attaching storefront tubing to substrates, and whose extra-long length offers a reliable grip when installed correctly.
  • Self-drilling sheet metal screws combine a drill and screw into a single unit to drill their own hole, cut or form mating threads, and achieve a complete fastening in a single operation.
  • Self-tapping machine screws with cross-cuts that allow them to tap their own threads in metal

Drive styles


Depending on drive styles, screws can be differentiated into:

  • Phillips
  • Slotted
  • Hex
  • Spanner Tamperproof, which are made from corrosion-resistant stainless steel and offer superior security given the fact that they cannot be removed without a matching spanner head screwdriver.
  • Square drive

Measuring screw lengths


Screw length is measured from where the material surface is assumed to be, to the end of the screw. For fasteners whose head usually sits above the surface, measure from directly under the head to the end of the fastener. For a countersunk fastener, such as a flat head, measure from the point on the head where the surface of the material is, to the end of the screw.


When ordering different types of screws, the nomenclature is as follows: