Torx Size Chart: T & E Size Table (Free PDF)

Use calipers to measure across two opposite points of screw recess (or across the tip of your bit).

Find the measurement you read off the calipers in the Point to point columns of the table. That's all there is to it.

Torx sizes run from T1 to T100; they aren't inches or millimetres so the number isn't a size: It's just a number in a series. At the bottom end of the scale, the step between adjacent numbers is small. On small screws, a mismatched bit will seat and feel almost right.

Towards the top, however, the step is large. So try the next sizes up or down if a bit doesn't fit properly; does it then wobble? Is it sitting proud? Before you turn.

Torx size is the number stamped on drivers, bits and keys.

Point to point refers to the six lobe (hexalobular) profile standardized as ISO 10664, which is the width across the tips of opposing lobes. These are the driver tip dimensions shown on tool maker charts. The corresponding screw recess is cut a couple of hundredths of a millimetre larger than that so the bit fit into the slot.

The max torque is the range the drive geometry itself can absorbs without failing or causing the bit or the recess to be reamed out. It’s a drive capability, not a tightening specification.

Actual assembly torque comes from the manufacturer’s torque table plus thread size and fastener grade, and it will sit well below max torque for most joints. Convert Nm to lbf ft by multiplying by 0.738.

These two screw pairing columns is just typical matches taken from fastener manufacturer selection charts; it's not the standard. Head style determine the pairing.

A #8 pan head, for example, would typically be paired with a T20 recess. A similarly sized #8 socket cap goes with T25. Set screws (same thread size) is one or more sizes smaller than pan heads.

In metric, all this holds true, so there are multiple rows with a couple thread sizes listed. At T55+ you’re mostly seeing metric machinery/structural bolt pairings; no sensible imperial pairing are offered.

Note the number traps. Numbering jumps on purpose. No tools from T10 to T15. None from T15 to T20. None from T30 to T40. For instance, if you see T22, that is a misnumbered or special tool mark.

Very rarely used manufacturers has a couple of in between sizes (T35, T47) in some catalogues but so rarely made that most bit sets don't include them. Values aren't listed since no consistent published dimensions exist.

Do not mistake Torx for similar looking drivers. Square Robertson, internal hex recess and Apple's five lobe pentalobe all strip out fast if you try to use a jammed Torx bit.

This is only for standard internal six lobe Torx. There are separate tables further down the page for: external hex head style E sizes; Torx Plus (IP) with its squared lobes; and for tamper resistant pin in head variants.

The T number can NEVER be used interchangeably with an E number. A standard bit will not fit into the recess of a pin-in-head security screw.

Match your measurement in the Point to point columns. You measure across two opposite spots on the male star head on the bolt. Then choose the socket marked with that same E size.

Unlike the more common recessed heads, external Torx are found on the bolt as a protruding six-lobe star. The tool are a wrench or socket with an opening to match. Although they may look similar, an E socket doesn’t interchange with a T bit.

The socket size is E. Point to point is width across the lobe of the bolt head. The opening of the socket are slightly enlarged to fit over the head.

Typical bolt threads match common fastener sizes. These come from charts by the manufacturers. It is not a rule but a suggestion. Often times a car maker will have a small bolt with a bigger head just for clearance reason.

No set size because charts do not agree, so E16 is listed without a firm metric pairing. Check your car's owner manual to double check your size.

The closest T profile compares internal T bits to E sockets by looking at the closest point-to-point width. Two number system do not relate. A T8 bit will not fit into an E8 socket. It’s closer to a T45 or maybe T40.

There are only select ones that match exactly like T20 & E4, T30 & E6, T55 & E12, or T100 & E24. Charts you find published frequentely have a loose pair off by one size.

Use this column for ID purposes only. Don’t try using one tool where the other won’t fit; it’s a loose fit which can cause rounding when under torque.

The other error is that folks will grab a hex socket for an exterior Torx head. That’s not going to work. A 12-point socket will often seat on the star, then shear the lobe corners the moment real torque arrives.

On E10 and E12 engine bolts, this rounds out the lobe corners. Same thing with trying to use an E socket on a hex bolt. It fails the same way: if the head look like a star with rounded valleys, then you use the E socket, ‘cause E heads are shallow. You push it all the way home, the socket grab just the top few millimeters.

The 1/4 inch drive include E4 through E8.

Use a 3/8 inch drive for E10 through E14.

The 1/2 inch drive includes E16 through E24.

Special order: Size E25 and above

Rare: Size E11, which appears between E10 and E12.

The big bolts goes as high as E44 in the series. Special order sizes are available over E24.

Note that this doesn’t include the Torx Plus heads. Those have a squared lobe form instead of a six lobe star and use EP numbers. The next table show the Torx Plus heads.

So treat it like the T series and read it in the same manner. The Drive size use the same point to point scale as the T number. So if you have a T25 then your bit will be a 25IP with the same nominal tip size. Measure from opposite sides of the recess and grab the match IP size.

Second generation drive from the Torx licensor is called Torx Plus. It is based off an ellipse instead of a circle so the lobes is squared off. Drops the drive angle from 15 degrees down to 0 degrees but puts more metal behind each lobe of the bit.

Min bit torsional strength is quoted in lbf in and Nm. This is the licensor’s published minimum torque a bit of that size will survive during a fixed head laboratory drive test. Never use it as an assembly torque: real joints is tightened to the fastener specification, which is well below these failure numbers. Use it instead to sanity check the setting on your power tools, and to compare sizes.

The typical screw columns come from the licensor’s drive size selection chart. They shift with head style like standard Torx bits, where a range like #8 to #12 covers socket, flat, and pan head patterns. Blank cells (4IP, 9IP) is sizes where no standard screw selection listing exist. These are sold as tooling for special OEM fasteners.

The trap that dooms recesses is compatibility. It only works one way. A standard T bit physically fits an IP recess of the same number and can turn it lightly. However, it bears on small contact patches, and both will wear quickly if torqued. An IP bit will NOT fit snugly into a plain T recess, and should of not been made to.

If you mix equipment that uses both generations, get yourself some IP bits: They’re the right tool where IP screws want ’em, but they’re the wrong but survivable tool nowhere. External Torx Plus heads feature their own EP numbering (1EP thru 42EP) and corresponding sockets; the same one-way logic also applies to E sockets.

You will mostly find Torx Plus in mass manufacturing, such as screws for automotive production lines, appliances, and electronics assembly. In these uses, a 0-degree drive angle eliminates cam out, allows for higher seating torque with the same size bit, and reduces bit changes.

In service manuals, screws are noted, and often marked, as IP size. The recess looks like a Torx but has flatter, gear-like lobes. If a supposedly right T bit seem loose in a fresh recess, suspect Torx Plus before suspecting worn screw head.

To figure out which one it is, read left-to-right down the table, then look at the Driver required column to see if you have that tool or not. The Typical marking column indicates how they is marked on service manuals and on their package, and the Tamper feature column explain exactly what is mechanically keeping your standard bit from sliding in.

Security features do not change the point to point measurements of plain versions, so a T25 with a pin in the center are just a TR25 recess.

The common security version have a center pin and keeps the 6 lobe shape. The matching driver is just a T bit which have a hole bored into the end. It is sold as TR (Tamper resistant) or with an S or H suffix. This is a match for the security screw.

Security bits are weakened by removing material from the core so they are not as strong as a similarly sized solid bit. Use security bits to get past the pin, then switch to solid bits to keep applying high torque to the screws without pins.

Torx pin-in-head screws is used in appliance housings, sanitary and public infrastructure hardware, consoles, and electronics.

Not so with Torx Plus security (IPR), whose five squared shapes surround a solid post. This will not turn with standard Torx bits or bored TR bits. There is no hex key for this or any other general-purpose Torx Plus driver. The licensor distributes tooling only through controlled channels.

SAE J2317 specifies this as a tamper-resistant drive. It is used on things you shouldn’t get into, such as limited-access devices and pedestrian safety equipment.

Order the correct IPR size from an industrial supply house if you see a five-lobed post-in-recess combination, because trying to extract it yourself will typicaly ruin the head.

Wrong screws waste your money. No, those aren't Torx; that's an Apple pentalobe screw, which has no post and five round lobes. It requires its own driver.

And don't assume a T20 size is just standard Torx; a broken off pin in a six lobe recess can look like normal Torx until you bottom the bit on the stub.

Know what you get when you order: The size number follows the base geometry, and a TR20 bit fit a pinned T20 recess. Pinned security bits keeps their point to point value in table above. Don't let security change the numbers.

The Application area column direct you to read down the table to see what type of work is done there. You also know in the Typical sizes column what band of T or E series should be at the bench (engine work go in the E series). This overlaps on purpose because each manufacturer determine drive size based off head style and screw diameter different than on industry standards. Finally, the Watch out for column describe the most common mistake in this application.

For the vast majority of screws you are likely to encounter around your home, workshop, or on a car, it’s T10, T15, T20, T25, T27, T30 and T40. T25 really owns moddern wood frame building; T10 to T15 own electronics enclosure stuff.

Before you get into doing any European chassis or engine work, pick up some E10 to E18 sockets too, those bolts cannot be turned propery with anything else. If it get turned by an impact tool, buy impact rated bits. Same sized drive as everything above, different steel in the bits.

The dimensional tables above are not replaced by this little reference. Each industry have their own habit sizes, and every product may be different.

If the bit is a bit too loose, check it against the point-to-point dimensions in the T and E tables. If the recess have a pin or unusually flat lobes or five lobes then check out the variants table. The torque doesn't come from size of the recess but rather the spec by the equipment manufacturer. You should of checked the spec.