• 19 parts
  • Checked September 2026

Parts of a Screw

A wood screw from head to point, its thread enlarged, and seven head shapes to tell apart.

Parts of a Screw

Name Date

Tap any part to read, rename or leave it out

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
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Write the name of each numbered part.Answer key

  1. Head
  2. Shank
  3. Thread
  4. Point
  5. Slot
  6. Flat head
  7. Round head
  8. Pan head
  9. Oval head
  10. Hex head
  11. Truss head
  12. Fillister head
  13. Pitch
  14. Crest
  15. Root
  16. Major diameter
  17. Minor diameter
  18. Flank
  19. Thread angle

Drawn for this site by script, 2026-09-23, from the thread and head definitions in the sources. Licence: own work.

Each numbered ring is a button. Use the arrow keys to move between them and Enter to choose. Names are read out in Study, and once a part is answered.

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All 19 parts on the diagram

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Wood screw 5

  1. Head The end you turn; this one is countersunk to sit flush.
  2. Shank The body under the head. A wood screw leaves its top part plain.
  3. Thread The spiral ridge that pulls the screw in. About two-thirds of the length.
  4. Point It is the tapered tip. The thread runs into it to start in the wood.
  5. Slot The groove a flat screwdriver fits: the simplest drive.

Head shapes 7

  1. Flat head Countersunk: its flat top sits level with the surface.
  2. Round head A dome that sits on top of the surface.
  3. Pan head A low disc with a high, rounded outer edge.
  4. Oval head Countersunk underneath, rounded on top: it stands a little proud.
  5. Hex head Six flat sides, turned with a wrench instead of a screwdriver.
  6. Truss head A wide, low dome.
  7. Fillister head A tall cylinder with a slightly rounded top.

The thread, enlarged 7

  1. Pitch The distance from one crest to the next, along the axis.
  2. Crest The top of the thread, farthest from the core.
  3. Root The bottom of the groove between two turns of thread.
  4. Major diameter Measured over the crests: the screw's full size.
  5. Minor diameter Measured across the roots: the solid core.
  6. Flank Either sloping side joining a crest to a root.
  7. Thread angle The angle between two flanks: 60 degrees on most V-threads.

How this list was compiled: Read 2026-09-23. (1) Wikipedia, Screw, https://en.wikipedia.org/wiki/Screw: head, non-threaded shank, threaded shank and tip of a wood screw; pitch; the head shapes pan, dome, round, truss, flat (countersunk), oval (raised), fillister and hex cap; a slotted drive. (2) Wikipedia, Screw thread, https://en.wikipedia.org/wiki/Screw_thread: crest, root, flank, major and minor diameter, the thread angle of most V-threads at 60 degrees. (3) William Noyes, Handwork in Wood (1910), chapter on fastenings, Project Gutenberg #20846, https://www.gutenberg.org/ebooks/20846: flat, round, fillister and oval-countersunk heads; the slot for the screwdriver; the thread begins in a fine point and runs about two-thirds of the length; countersinking a flat head flush. (4) A US federal screw-thread standards handbook (1969), https://nvlpubs.nist.gov/nistpubs/Legacy/hb/nbshandbook28-1969p1.pdf, paragraphs 5.18 to 5.24 and 6.2 to 6.21: flank, crest, root, pitch, included angle, major and minor diameter. (5) A space agency's fastener design manual (1990), https://ntrs.nasa.gov/api/citations/19900009424/downloads/19900009424.pdf: head styles hex, flat, round, oval, fillister, pan and truss (fig. 33); countersunk heads commonly 82 or 100 degrees; root and crest. Licence: own work

The drawing: Drawn for this site by script, 2026-09-23, from the thread and head definitions in the sources. Licence: own work

How it works

A screw has a head, a shank and a thread that ends in a point. The head carries the drive, here a slot, and its shape decides whether it sits flush or stands above the surface.

Read the full guide

Head, shank, thread, point

Under the head, a wood screw keeps the top of its shank smooth. The thread covers about the last two-thirds and runs right into the point, so the screw can start in soft wood.

Reading a thread

Each turn of thread has a crest on the outside and a root in the groove, joined by two flanks. Pitch is the distance from one crest to the next. The major diameter is measured over the crests, the minor diameter across the roots.

  • Flat and oval heads need a countersunk hole; round, pan, truss and fillister heads sit on the surface.

Questions and answers

What are the parts of a screw called?

The head with its drive, the shank under it, the thread (the spiral ridge) and the point. The thread has crests, roots and flanks, and is measured by its pitch and its major and minor diameters.

What is the difference between a flat head and a pan head screw?

A flat head is countersunk: a cone underneath lets its flat top sit level with the surface. A pan head is a low disc with rounded edges that sits on top of the surface.

What is the pitch of a screw?

The distance from one crest of the thread to the next, measured along the screw. A fine thread has a smaller pitch than a coarse one, so it makes more turns in the same length.

Why is the top of a wood screw not threaded?

The plain shank passes freely through the top piece, so only the thread in the lower piece grips. Turning the screw then draws the two pieces tight together.

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