How to Measure a Torx Bit

Textron's line of Torx-head bits and screwdrivers are designed to be used specifically with Torx-head screws. The bits are six-point splines, the individual sizes of which are measured in a standard known as "T-sizes." If you ever come across a Torx bit that's mislabeled or doesn't have a T-size on it, you can figure out the exact T-size with a ruler and a chart from Textron.

A ruler, pencils and paper on a desk.
Image Credit: Alexey Klementiev/iStock/Getty Images

Things You'll Need

  • Ruler

  • Paper

  • Pencil

Step 1

Line up the ruler on the star-shaped screw tip to measure from one point to the point directly opposite.

Step 2

Examine the markings on the ruler and write them down.

Step 3

Compare the measurement with the "P to P" (point to point) column of the first chart on the Wiha website to determine your Torx bit's exact T-size. You can measure in inches or millimeters. The Wiha link can be found in Resources.

references & resources