Torx Bit Sizes Guide

Yes — "Torx" and "star bit" refer to the same six-pointed star drive geometry. "Torx" is the trademarked brand name developed by Camcar Textron in 1967; "star bit" or "star drive" is the common Australian and UK casual term for the same six-lobe drive (covered by ISO 10664). On engineering drawings the abbreviation TX is used. Be careful not to confuse Torx with Pentalobe (five-point, used by Apple) or Hex Plus (Wera's enhanced hex drive) — both can look star-shaped but are NOT Torx-compatible. The simplest visual check is to count the points: six = Torx, five = Pentalobe.

Torx vs Star vs Other Star-Shaped Drives — Quick Reference

What Is a Torx Bit?

A Torx bit is a screwdriver bit with a six-pointed star-shaped tip, designed to engage a matching six-lobe recess in a fastener head. The Torx system was developed in 1967 by Camcar Textron (now Acument Intellectual Properties) as a high-torque alternative to Phillips and slotted drives. It is patented and trademarked — "Torx" is the brand name; the underlying geometry is technically a "six-lobe drive" and is covered by ISO 10664.

In Australian workshops, Torx is most commonly called Torx by tradespeople familiar with the brand, and star bit or star drive in casual conversation — particularly on building sites where the bit category matters more than the brand. On engineering drawings the abbreviation is TX followed by the size number, e.g. "TX25". All three terms refer to the same six-lobe drive geometry.

Torx sizing uses a T-number for internal drives (T10, T15, T20, T25, T30, T40 etc.) where the bit fits into a recess in the screw head, and an E-number for external drives (E6, E8, E10 etc.) where the screw or bolt has a six-lobe external profile and the bit is a socket that fits over the head. The numbering systems are independent — an E8 external Torx is roughly equivalent to a T40 internal Torx, not a T8 — which is one of the most common buying errors in the category.

This guide covers internal Torx (T-series), external Torx (E-series), Torx Plus, security Torx, and the proprietary lookalikes (Pentalobe, Hex Plus) that get confused with standard Torx. AIMS holds the full Sutton, Ko-Ken, Wera and Wiha Torx range — see torx screwdrivers and screwdriver bits.

Why Torx? Drive Comparison vs Phillips, Pozi and Hex

Torx exists because the older drive systems have a fundamental geometric weakness: their drive surfaces are angled in a way that converts torque into cam-out — the bit lifts out of the recess under load, stripping the head. Phillips drives were originally designed with intentional cam-out (to limit overtightening on early production lines), but on a high-torque modern power driver, that "feature" becomes a defect.

Torx is engineered for the opposite outcome. The six lobes contact the bit at six points, the contact surfaces are nearly perpendicular to the rotation direction, and there is almost no axial force component. The bit stays seated under load — torque transfers cleanly into the screw rather than lifting the bit out of the head.

The Reddit consensus across r/Tools, r/DIY and r/Construction is consistent: for stripping resistance and torque transfer with internal drives, Torx is the best general-purpose choice. The only drives that beat it on raw strip resistance are external (visible spanner-driven heads), and the only situations where Phillips genuinely wins are intentional torque-limited assembly.

For a complete drive comparison covering every major recess type and how to identify them on existing fasteners, see our Screwdriver Types Guide.

Torx Size Chart — T1 to T100

Torx sizing runs from T1 (smaller than a pencil tip, used in micro-electronics) through T100 (used in heavy industrial machinery and earthmoving equipment). The point-to-point diameter — the dimension across opposite lobes — increases with the T-number.

The most commonly stocked sizes in Australian general supply are T10, T15, T20, T25, T27, T30, T40 and T45. A standard 8-piece or 10-piece Torx bit set will cover this range and handle 90% of fastening jobs an AU tradesperson encounters.

If a screw drive looks like Torx but a T-number bit will not fit cleanly, check whether you are looking at an external Torx (E-series), a Torx Plus, a security Torx with a centre pin, or a non-Torx lookalike (Pentalobe, Hex Plus, tri-wing). Each has its own bit type — covered in the sections below.

Internal Torx (T) vs External Torx (E)

Internal and external Torx are completely different products that share the same lobe geometry but operate in opposite directions.

Internal Torx (T-series)

The bit is a small star-shaped tip that fits into a recess in the screw head. The fastener head has a six-lobe hole; the bit fills it. Standard sizing: T1, T2, T3 ... T100. This is the more common form and the type most people mean when they say "Torx".

External Torx (E-series)

The bit is a socket with a six-lobe internal profile that fits over a six-lobe boss on the bolt or screw head. The fastener has a star-shaped head; the bit is a socket that envelops it. External Torx sizing uses an E-prefix: E5, E6, E7, E8, E10, E12, E14, E16, E18, E20, E24.

External Torx is most commonly seen in European automotive engineering — engine block bolts, transmission casings, brake caliper mountings — where the high-torque transfer of an external profile combines with the strip resistance of the Torx geometry. Mercedes, BMW, Audi, and Volvo specify external Torx widely.

Torx Plus — The Engineered Upgrade (IP / EP)

Torx Plus is a refinement of the standard Torx geometry, introduced when the original Torx patent expired in the early 1990s. The lobes are squared off and the drive angle is reduced from 15° (standard Torx) to 0° (Torx Plus). The result is a bit profile with greater contact area, lower stress concentration, and noticeably higher torque transfer before deformation.

Compatibility:

• A standard Torx bit will fit into a Torx Plus screw recess — but with reduced contact area and somewhat compromised torque transfer. It works but you will not get the full benefit.
• A Torx Plus bit will not fit a standard Torx screw recess properly — the squared lobes do not match the rounded profile.
• If a fastener is specified as Torx Plus (IP25, IP30, EP8 etc.), source the matching Torx Plus bit. If specified as standard Torx, either type will work.

Torx Plus is most commonly encountered in high-end automotive (premium European brands), aerospace, medical devices, and CNC production environments where the marginal performance gain matters.

Security Torx — Tamper-Resistant with Centre Pin (TR)

Security Torx — also called Tamper-Resistant Torx or Torx TR — is a standard Torx recess with a small post in the centre of the star. The centre pin prevents a standard solid Torx bit from being inserted, requiring a security Torx bit with a corresponding hole drilled through the centre to clear the pin.

Sizing follows the same T-number convention as standard Torx, with an "S" suffix or "TR" prefix to indicate the security version: T15S, T20S, T25S, T30S etc. (sometimes written TR15, TR20).

Where security Torx is used

• Public infrastructure — bus seating, signage, public toilets, transit fittings
• Retail security — anti-theft brackets, display fixtures, point-of-sale hardware
• Electronics enclosures — gaming consoles, set-top boxes, equipment that should not be opened by users
• School and laboratory equipment — preventing unauthorised disassembly
• Vehicle anti-theft — number plate fixings, badge mountings, security panels

Compatibility — important

A security Torx bit (with the centre hole) will fit a standard non-security Torx screw — it just has a hollow centre that does not engage anything. So a security Torx bit set covers both security and standard Torx fasteners, at the cost of slightly weaker bit shafts. A standard Torx bit will not fit a security Torx screw — the solid centre of the bit clashes with the screw's centre pin.

If you do not know in advance which type you will encounter (e.g. servicing public infrastructure, school equipment, or retail fixtures), specify a security Torx bit set — it covers both. AIMS holds Sutton S113 Tamper Resistant Torx inserts and Ko-Ken security Torx bits — search the screwdriver bits collection.

Torx Is Not the Same as Pentalobe or Hex Plus

Several proprietary drive systems look superficially similar to Torx but are not compatible. Confusion is common — at quick glance they all look like a six-pointed star — and using the wrong bit will round out the recess.

Pentalobe (5-point)

Apple's proprietary drive used on iPhones, MacBooks, and other Apple devices. It has five lobes instead of six. A Torx bit will not fit a Pentalobe recess and a Pentalobe driver will not fit a Torx recess. The visual cue: count the points. Five = Pentalobe; six = Torx. Pentalobe drivers are sold as P2, P5, P6 etc. — not interchangeable with anything else.

Hex Plus (Wera)

Wera's enhanced hex driver geometry. It is not Torx — it is an upgraded six-flat (hex / Allen) drive with rounded contact corners. Hex Plus bits are stamped "Hex Plus" or "HEX-PLUS" by Wera and have a slightly different cross-section to standard hex. A standard hex bit will fit a Hex Plus recess; a Hex Plus bit will fit a standard hex socket. Confusion arises because both Hex Plus and Torx are marketed as "anti-cam-out" — they solve the same problem with different geometries.

Tri-wing, Tri-groove, Spanner head

Other security / specialty drives that look star-like but use different geometries. Tri-wing has three asymmetric points; tri-groove has three grooves (used in firearms, gaming hardware); spanner head has two pin holes (used in security applications). All require their own dedicated bits — none are Torx-compatible. For the security-head overview, see our Screw Head Types Guide, which covers the security drive family alongside the head shapes.

Choosing the Right Torx Bit — Insert, Impact and Hand Driver

"Torx bit" is a category that includes several physical formats. The right choice depends on the tool you are driving with and the torque you intend to apply.

1/4-inch hex shank insert bits

The standard format — a short bit with a 1/4" hex shank that fits into screwdriver bit holders, magnetic adapters, and the chuck of a power drill or impact driver. Most Torx bits sold in Australia are this format. The Sutton S111 series (CRV inserts) is a typical example — 25 mm long, hardened chrome-vanadium steel, 1/4" hex shank. Available individually and in sets covering T10 through T40.

Impact-rated bits (for impact drivers)

Standard insert bits will fracture or twist under the cycling torque of an impact driver. Impact-rated Torx bits use harder steel alloys and a torsion zone — a section of the bit shaft engineered to flex slightly under impact loading, dissipating shock that would otherwise crack the tip. Sutton S169 (Ultrabit) and S212 / S214 (Supatorq) are the AU industrial impact options. Ko-Ken impact Torx bits are also stocked. Use impact-rated bits exclusively in impact drivers; standard bits will not survive.

Long-reach bits and power bits

For applications where the screw is recessed below the surface — counterbored holes, deck screws driven through joists, automotive engine bay fasteners — extended-length Torx bits are required. Common lengths: 50 mm, 75 mm, 100 mm, 150 mm. Sutton holds the AU range; Wera and Wiha offer longer specialty lengths.

Hand drivers — T-handle and screwdriver-style

For repeated assembly or in confined spaces, dedicated Torx hand drivers are often more efficient than a bit + holder. A T-handle Torx driver gives high torque from a balanced grip; a standard screwdriver-style handle is lighter and faster for lower-torque work. AIMS holds the Sutton range and the Ko-Ken impact-style screwdriver bits — see the torx screwdrivers collection.

Sockets and ratchet drives (for E-series)

External Torx is driven by a socket on a 1/4", 3/8", or 1/2" ratchet — same as a standard hex socket but with a six-lobe internal profile instead of six flats. AIMS stocks Ko-Ken external Torx sockets in the common automotive sizes (E8 through E20).

Common Torx Applications in Australian Work

Decking and structural timber screws

The most significant shift in AU construction over the last decade has been the move from Pozidriv to Torx on decking and structural timber screws. Premium brands — Macsim, Spax, Klein, and most Class 3 and Class 4 timber screws — are now supplied with T20, T25, or T30 Torx drive. The reason is power-driver compatibility: a Pozi bit cams out of the head under the high cycling torque of a modern impact driver; a Torx bit holds. T25 is the most common decking screw size in AU domestic construction; T30 for heavier structural work.

Automotive — interior and powertrain

European automotive (BMW, Audi, Mercedes, Volvo, VW) uses Torx widely throughout interior trim, dash panels, brake hardware, and powertrain components. T15 to T30 dominates interior work; T40 to T55 typical for engine and gearbox structural; external Torx (E10 to E20) for engine block and transmission bolts. Japanese and Korean vehicles increasingly adopting Torx — Nissan, Toyota, Hyundai, Kia all use T15 / T20 / T25 in modern interior trim.

Electronics and IT hardware

T6 through T10 dominate laptops, monitors, gaming consoles, and small electronics. Server hardware uses T15 widely. Specialty pin-in (security) Torx is common on customer-facing equipment to deter unauthorised opening.

Public infrastructure and retail

Security Torx (T15S to T30S) used widely on bus seating, train fittings, retail display fixtures, public toilets, signage, vehicle plates, and any fixture that needs to resist tampering by passing public.

Bicycle, motorcycle and outdoor gear

High-end bicycle components (Shimano, SRAM) use T25 / T30 widely on disc brake mounts and chainring bolts. Motorcycle bodywork increasingly Torx-driven. Outdoor gear (camping equipment, bike racks, rooftop tents) often Torx for vibration resistance.

AIMS Industrial Torx Range — Brands and Stock

The AIMS Torx range covers individual bits, sets, hand drivers, impact-rated tooling, and specialty long-reach bits. Key brands stocked:

Sutton

Australian-owned tooling specialist with a deep AIMS-stocked range:

• Sutton S111 — standard Torx insert bits, CRV (chrome-vanadium) construction, 25 mm length, 1/4" hex shank. Sizes T10 through T40. The general-purpose AU workshop bit.
• Sutton S113 — tamper-resistant (security) Torx insert bits, CRV. The same dimensions as S111 but with the centre hole for security Torx fasteners.
• Sutton S169 Ultrabit — impact-rated Torx insert bits with torsion zone. Up to 12× the life of a standard bit in impact-driver work.
• Sutton S212 Supatorq — Custom S8 steel power bit, 1/4" hex shank, impact-rated for high-torque applications.
• Sutton S214 Supatorq — same Custom S8 steel platform with security Torx-S geometry, 150 mm long-reach option for deep-recessed fastenings.

Ko-Ken

Japanese precision tooling specialist, particularly strong in impact-rated and socket products:

• 1/4" drive Torx screwdriver bits — full T-series and TR (security) range
• Impact-rated Torx bits — sizes including T45 long-reach for automotive applications
• External Torx sockets — E8 through E20 in 1/4" and 3/8" drive for engine and gearbox work

Champion

Specialty fastener tooling — tamper-resistant Torx and security driver kits. The Champion family includes the OWS-RT One-Way Screw Removal Tool used widely by locksmiths and security technicians.

Wera and Wiha

German precision tooling — premium specialty Torx bits for production, aerospace, and CNC environments. Available to order.

Browse the full range: Torx screwdrivers | Screwdriver bits. For the broader drive-recess context covering all bit types, see our Screwdriver Types Guide. For the head-shape companion, see our Screw Head Types Guide.

Frequently Asked Questions

What is a Torx bit?

A Torx bit is a screwdriver bit with a six-pointed star-shaped tip designed to engage a matching six-lobe recess in a fastener head. The system was developed by Camcar Textron in 1967 as a high-torque alternative to Phillips and slotted drives. "Torx" is the brand name; the underlying geometry is a six-lobe drive covered by ISO 10664. In Australian shop language it is also called a "star bit" or "star drive" — all three terms refer to the same thing.

What sizes do Torx bits come in?

Internal Torx bits are sized from T1 (smaller than a pencil tip, used in micro-electronics) through T100 (heavy industrial machinery). The most commonly stocked sizes in Australian general supply are T10, T15, T20, T25, T27, T30, T40 and T45 — these handle 90% of the fastening jobs an AU tradesperson encounters. External Torx (E-series) uses an independent numbering system from E5 through E24 — these do not correspond to T-series numbers.

Is a star bit the same as a Torx bit?

Yes — "star bit" or "star drive" is the common Australian and UK casual term for a Torx bit. "Torx" is the trademarked brand name; the underlying six-lobe geometry is the same regardless of which term you use. On engineering drawings the abbreviation TX (e.g. TX25) is also used. Be careful not to confuse Torx with Pentalobe (5-point, used by Apple) or Hex Plus (Wera's enhanced hex drive) — both can look similar at a glance but are not Torx-compatible.

How do I know what Torx size I need?

The fastener manufacturer or equipment manual is the best source. If you do not have that, the practical method is to try bits from a Torx set in order, starting one size smaller than your visual estimate and moving up. The correct Torx size will fully seat in the recess with no rocking and no gap; if the bit feels loose or rocks, go up one size. If it will not enter the recess, go down one size. Common decking screws are T25 or T30; computer hardware T8 or T10; automotive interior trim T15 to T30.

What's the difference between Torx and Torx Plus?

Torx Plus is a refined version of the original Torx geometry developed when the original patent expired. The drive angle is reduced from 15 degrees to 0 degrees and the lobes are squared off, giving up to 25 percent greater contact area and almost nil cam-out under high torque. Sizing uses an IP prefix for internal Torx Plus (IP25, IP30) and EP for external (EP8). A standard Torx bit will fit a Torx Plus recess with reduced contact, but a Torx Plus bit will not properly fit a standard Torx recess. Torx Plus is most commonly seen in premium automotive, aerospace, and CNC production environments.

What's the difference between internal Torx (T) and external Torx (E)?

Internal Torx (T-series) is a recess in the screw head — the bit is a small star tip that fits into the head. External Torx (E-series) is a six-lobe profile on the outside of the bolt head — the bit is a socket that fits over the head, like a hex socket. The numbering systems are independent — an E8 external Torx is roughly equivalent to a T40 internal Torx, not a T8. Always confirm whether a fastener requires internal or external Torx, then specify by the correct prefix. Buying assumption errors here are the most common Torx purchasing mistake.

What is a security Torx bit?

A security Torx bit — also called Tamper-Resistant Torx or Torx TR — is a Torx bit with a hole drilled through the centre to clear a small pin in the centre of a security Torx fastener recess. The pin prevents a standard solid Torx bit from being inserted, deterring unauthorised tampering. Security Torx bits will fit both security and standard Torx fasteners (the centre hole simply has nothing to engage on a standard fastener), but standard Torx bits will not fit a security Torx fastener. Common applications include public infrastructure, retail security, electronics enclosures, school equipment, and vehicle anti-theft fittings.

Is Torx Plus the same as security Torx?

No — these are commonly confused but completely different products. Torx Plus is a refined geometry with squared lobes and a 0-degree drive angle, designed for higher torque and lower cam-out — sizing uses IP and EP prefixes. Security Torx (TR) is a standard Torx geometry with a centre pin in the fastener and a hollow centre in the bit, designed to prevent unauthorised disassembly — sizing uses an S suffix or TR prefix. Torx Plus has no security feature; security Torx has no enhanced geometry. Different problems, different solutions.

Why are Torx screws better than Phillips?

Torx geometry distributes drive torque across six points with contact surfaces nearly perpendicular to the rotation direction — there is almost no axial force component lifting the bit out of the recess. Phillips drives have angled contact surfaces that intentionally cam out under high torque (originally a feature for early production line torque limiting; now a defect on modern impact drivers). The result: Torx is dramatically more strip-resistant than Phillips, particularly under power-driver work. The Reddit and tradesperson consensus is consistent: Torx is the best general-purpose internal drive for stripping resistance and torque transfer.

Can a regular Torx bit fit a security Torx screw?

No. The pin in the centre of a security Torx recess prevents a standard solid Torx bit from seating fully. You need a security Torx bit (with a corresponding hole drilled through the centre to clear the pin) to engage a security Torx screw. The reverse works: a security Torx bit will fit a standard non-security Torx screw, because the centre hole simply has nothing to engage. If you are servicing equipment where you do not know in advance which type you will encounter, specify a security Torx bit set — it covers both, at the cost of slightly weaker bit shafts due to the hollow centre.

What's the difference between Torx and Pentalobe?

Torx has six lobes; Pentalobe has five. Pentalobe is Apple's proprietary drive used on iPhones, MacBooks, and other Apple devices, sized as P2, P5, P6 etc. The two systems are visually similar at a glance — both are star-shaped — but they are not interchangeable. A Torx bit will not engage a Pentalobe recess and vice versa. The simplest visual check is to count the points: five points means Pentalobe; six points means Torx. Pentalobe drivers are sold separately and are not stocked in standard Torx bit sets.

Are Torx bits compatible with impact drivers?

Standard Torx insert bits are not — they will fracture or twist under the cycling torque of an impact driver. Impact-rated Torx bits use harder steel alloys and a torsion zone (a section of the bit shaft engineered to flex slightly under impact loading) to dissipate shock that would otherwise crack the tip. Sutton S169 Ultrabit, S212 Supatorq, and Ko-Ken impact Torx bits are the AU industrial standards for impact-driver work. Always use impact-rated bits in impact drivers — using a standard insert bit in an impact driver is a guaranteed bit failure within minutes.