Screw Sizes

Screw Sizes

General sizes of screws - The first number refers to the gauge or width of the shank and the second to the length, in inches.

Generally the gauge can be converted to millimeters as follows:

  • 6 = 3mm
  • 8 = 4mm
  • 10 = 5mm
with each increase in gauge corresponding to a 0.5mm increase.

When drilling pilot holes, a drill bit slightly smaller than the gauge should be used. Therefore an 8 gauge screw would use a 3mm pilot hole, a 6 gauge a 2mm and so on.

There's more information on ths page about Screw Sizes.