Tool knowledge

Commonly Used Torx Screwdriver Size Specifications Chart

Commonly Used Torx Screwdriver Size Specifications Chart

The hexagonal Torx screwdriver model is divided by the distance (diameter) of the diagonal points of the Torx head measured with a vernier caliper.

The diameter of T8 is 2.31mm.

The diameter of T10 is 2.74mm.

The diameter of T15 is 3.27mm.

The diameter of T20 is 3.86mm.

The diameter of T25 is 4.43mm.

The diameter of T27 is 4.99mm.

The diameter of T30 is 5.52mm.

Torx screwdriver size specification table

The specifications in the above metric system are the answer you want. The diameter of the plum hexagon head measured with a vernier caliper is the simplest and clearest. Some netizens don't know what they are, and they have no reference value at all. The quincunx has holes or no holes in the center. Generally, small ones like T6 are mostly without holes, which are small in themselves, and those with holes are difficult to make and unnecessary.

Security Torx

Security Torx screws are often called Pin Torx due to the additional pin at the centre of the six-point star socket head. This centre pin makes it impossible to use a standard Torx screwdriver, making this type of fastening tamper-proof.

Standard and Security Torx Heads

Security Torx screws are sometimes called: 6 lobe screws, tamper proof Torx, 6 lobe pin torx, torx TR, torx pin and star pin drive screws. Tamper-proof security Torx screws provide a higher level of security than standard Torx due to the specialized security Torx screwdriver that’s needed to loosen them.

Security Torx Screwdrivers

As noted, standard 6-point Torx screwdrivers will not mate with security Torx screws due to the additional centre pin in the socket head. To use security Torx screws requires appropriate tools which accommodate the additional security pin.

Torx Screwdrivers - Standard and Security

5 Point Torx Plus

A successor to the original Torx design was Torx Plus, introduced in 1990. This design made improvements on the original which enabled higher torque to be applied while minimizing wear.

A further development has been the introduction of the tamper-resistant variant of Torx Plus sometimes called Torx Plus Security or Torx Plus TR (tamper resistant). This form uses a 5-point star-shaped head socket with a center pin.

This five-point or five-lobed socket design is generally called a pentalobular socket. The revised design adds a further level of security and requires the use of appropriate tools that mate with the 5-point star socket and central security pin.

Torx Screw Sizes

As noted, it’s important to match the size of the Torx screw or bolt socket head with the correct size of Torx screwdriver. Here’s a chart showing the standard Torx sizes.

Torx Size

Imperial Point to Point (inches)

Metric Point to Point

Max Torque Range




.02 to .03 Nm




.07 to .09 Nm




.14 to .18 Nm




.22 to .28 Nm



1.42 mm

.43 to .51 Nm



1.70 mm

.75 to .9 Nm



1.99 mm

1.4 to 1.7 Nm



2.31 mm

2.2 to 2.6 Nm



2.50 mm

2.8 to 3.4 Nm



2.74 mm

3.7 to 4.5 Nm



3.27 mm

6.4 to 7.7 Nm



3.86 mm

10.5 to 12.7 Nm



4.43 mm

15.9 to 19 Nm



4.99 mm

22.5 to 26.9 Nm



5.52 mm

31.1 to 37.4 Nm



6.65 mm

54.1 to 65.1 Nm



7.82 mm

86 to 103.2 Nm



8.83 mm

132 to 158 Nm



11.22 mm

218 to 256 Nm



13.25 mm

379 to 445 Nm



15.51 mm

630 t0 700 Nm



17.54 mm

943 to 1048 Nm



19.92 mm

1334 to 1483 Nm



22.13 mm

1843 to 2048 Nm

Torx Sizes Chart

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