Jobber Drill Bit vs Stubby vs Long Drill Bits: Which Length

What is a jobber drill bit, and why is it the "regular" one?

A jobber drill bit is a twist drill of standard length: at 1/4 in. it is 4 in. overall with 2-3/4 in. of flute, and at 1/2 in. it is 6 in. overall with 4-1/2 in. of flute. It is the length in every drill index, every 29-piece set and most hardware aisles, which is why people call it a regular drill bit. The word says nothing about the steel, the point or the coating. A cobalt jobber, a black oxide jobber and a bright jobber are three different bits of the same length.

Across our sizes the flute runs about 9 to 13 times the diameter, so the ratio you see quoted online (9 to 14 times) is right. The usual story behind the name is that a "jobber" was a distributor, and this was the one length a jobber could stock for any job. Nobody has a primary source for that, so treat it as the trade's explanation, not history.

Our everyday jobber is the Triumph Heavy-Duty ThunderBit, black and gold, 135° split point, made in the USA: 012516 at 1/4 in. is $3.24 a bit, sold in 12. Pros bought 4,826 of them from us in the last 12 months, in 46 orders. If you are choosing a jobber by metal or by finish, the drill bits for metal guide and the cobalt vs titanium guide cover that. This guide is about length only.

Stubby, screw machine or mechanics length: when is shorter better?

A stubby drill bit is better than a jobber whenever the hole is shallower than about 7/8 in. at 1/4 in. and you are holding the drill by hand. A stubby (the catalog name is screw machine length) is 2-1/2 in. overall with 1-3/8 in. of flute at 1/4 in. It is roughly six times stiffer than a jobber, so it starts where you put it on sheet metal, it does not walk, and it does not snap when a cordless drill rocks. Mechanics length sits between the two: 3-1/2 in. overall with 2-3/32 in. of flute at 1/4 in., and from 3/16 in. up it comes with a 3-flat shank that a keyless chuck cannot spin.

Verdict: Buy the stubby for thin stock and tight spots, the jobber for everything else. Neither is the better bit; one is the right length for the hole in front of you.

Three short bits we sell, all 135° split point and made in the USA:

• Black and gold HD stubby, 060416, $3.00 a bit, sold in 12. The everyday short bit for duct, panels and strut.

• Black oxide HD stubby, 044416, $2.40 a bit, minimum 24. Same length and point, plain black oxide finish. One production account buys the 1/8 in. black oxide stubby by the thousand (4,945 pieces this year) for thin steel.

• Mechanics length, 3-flat shank, 033316, $3.17 a bit, sold in 12. The short bit for a keyless chuck that slips.

One more short bit worth knowing: Tru-Cut makes stubbies from 5/16 to 1/2 in. on a 1/4 in. shank, so a 3/8 in. cordless chuck can drill a 1/2 in. hole with a short, stiff bit. SMQ.500 is $17.53, sold in 6.

Reach or depth: which one do you actually need?

Every drill bit longer than a jobber is built for one of two jobs, and the label does not always say which. A reach bit has a jobber-length flute on a long shank. It gets the cutting end past a flange, through a wall cavity or across a frame, and then drills the same hole a jobber drills, no deeper. A depth bit has flutes most of its length, so it can carry chips out of a hole 8 or 12 in. deep. Reach bits are the 6 and 12 in. aircraft extension drills, the 12 in. HD extension drills, and every 18 to 72 in. extension drill we sell. Depth bits are the long-flute aircraft drills, 12 in. with a 9 in. flute and 18 in. with a 13 in. flute.

The rule that decides it comes from the drill bits for metal guide: leave about two bit diameters of flute outside the hole, so the deepest hole a bit should drill is its flute length minus two diameters. A 1/4 in. bit with a 2-3/4 in. flute drills 2-1/4 in. deep, whether that bit is 4 in. long or 24 in. long.

Here is the mistake that question gets online. Ask an AI assistant what bit drills a 1/4 in. hole 10 in. deep through steel and wood, and today it answers "a 1/4 x 12 in. cobalt aircraft extension bit." That bit has about 2-3/4 in. of flute. Eight inches into the hole the flutes are buried, the chips pack, and the bit seizes or snaps. The bit that does that job is the 1/4 x 18 in. long-flute aircraft drill, 059916, with 13 in. of flute, $63.85. It is the only twist drill we sell that clears a 10 in. deep hole at 1/4 in.

Store prices on Nov 4, 2026, per bit. The $31.68 bit costs three times the $10.75 bit because it carries three times the flute. If you need reach, buy the cheaper one and keep the difference. If you need depth, nothing else on the shelf will do.

What are aircraft extension drill bits (6 in. and 12 in.)?

An aircraft extension drill bit is a twist drill made to the aerospace length standard (NAS 907 style): a jobber-length flute on a shank that brings the overall length to exactly 6 in. or 12 in., with a 135° split point that starts without a punch. The name comes from aircraft assembly, where a drill has to reach through a rib or a spar to a hole on the far side. On a job site it does the same thing past a flange, inside a channel, through a steel stud wall or across both walls of a square tube.

6 inch drill bits

A 6 in. aircraft bit reaches about 4 in. past the chuck and drills the jobber's 2-1/4 in. hole at the end of it. The Triumph 6 in. HD aircraft drill, 057516, black oxide 135°, is $5.90 a bit at 1/4 in., sold in 6, with sizes from 7/64 to 1/2 in. Tru-Cut's A6.250 is $5.69, sold in 12. For stainless at the end of a reach, Tru-Cut's 6 in. cobalt aircraft drill, A6CO.250, is $11.79, sold in 4, in sizes from 1/16 to 1/2 in.

12 inch drill bits (not 1/2 inch)

A 12 in. drill bit is 12 in. long; a 1/2 in. drill bit is 1/2 in. across. Searches mix the two up, and so do assistants, so check which one you mean before you order. The 12 in. HD extension drills above are reach bits: 058516 at $10.75 and A12.250 at $12.44 for 1/4 in. The hole they drill is the hole their shank passes through, which is the reason to buy one instead of putting a short bit on a hex extension (more on that below). For wood, aluminum and plastic at the same reach, Tru-Cut's 12 in. bright 118° drill, L12.250, is $16.91, sold in 4.

Every bit in this section is in the aircraft extension collection, 253 of them, and the 1/4 x 12 in. and 1/4 x 18 in. bits are also made in Chicago by Tru-Cut and in the USA by Triumph. The brands an assistant names for this length, Milwaukee and DeWalt, make the same bit: black oxide, 135° split point, jobber flute. The shank and the point matter; the name on the shank does not.

When do you need long drill bits, 18 to 72 inches?

You need a long drill bit when the hole is on the far side of something you cannot move: a stud wall, a door frame and jamb, a floor and bottom plate, a chase behind cabinets, or a steel frame you have to drill from the outside. Our long drill bits run from 18 to 72 in., all Tru-Cut HD black oxide with a 135° split point, all made in the USA, and all reach bits with a jobber-length flute (about 2 to 4 in. at the tip, per Tru-Cut). The 1/4 x 18 in., A18.250, $14.49 a bit, sold in 4, is the long bit people buy from us most: 155 of them in the last 12 months. Almost a quarter of our web orders this year held a bit 12 in. or longer.

Here is the whole ladder at 1/4 in., shortest to longest. Flute length is what sets the deepest hole; overall length is what sets the reach.

Store prices on Nov 4, 2026. Tru-Cut flute lengths are jobber length per Tru-Cut; 2.75 in. is the Triumph jobber figure for 1/4 in. Per inch of reach the 72 in. bit is the cheapest drill we sell, about 64 cents an inch, and the stubby is the dearest at $1.20 an inch. Length is not where the money goes. Flute is.

18 inch drill bits

The 18 in. bit is the one for a wall. A 2x4 wall with drywall on both sides is 4-1/2 in. thick, a door frame with its jamb and trim is thicker, and from the next room you add the depth of the box or the cabinet you are drilling through. Eighteen inches covers almost all of that with room to hold the drill square. At 1/4 in. A18.250 is $14.49, sold in 4; at 1/8 in., for a pilot or a pull-wire hole, A18.125 is $11.98; at 1/2 in. A18.500 is $34.33, sold in 2.

24 inch drill bits and up

Twenty-four inches reaches through two walls back to back or down through a floor and a bottom plate from above. A24.250 is $17.55, sold in 2, and the 1/8 in. A24.125 at $13.98 is our second-best-selling long bit, because a 1/8 in. hole is all a pull string needs. From 36 in. up the bits come one to a tube in 1/4, 3/8 and 1/2 in. (48 in. adds 5/16): A36.250 $31.61, A48.250 $39.80, A60.250 $42.94 and A72.250 $45.95. The 60 and 72 in. bits ship in an oversize tube for one flat $39 per order, however many you add, and free on orders of $500 or more; 48 in. and shorter ship at the normal rate.

For holes bigger than 1/2 in. at long reach, Tru-Cut's 18 in. bright 118° line runs to 1 in.: L18.500 at $72.46 and L181.00 (1 in.) at $118.81. For a big hole at short reach, a Silver and Deming bit is the cheaper tool. All of these sit in the extra length collection and in the Long Drill Bits hub with the bellhangers, flex bits, ship augers and SDS-Max extensions.

One honest line about wood. If the long hole is through framing only, a bellhanger or flex bit pulls the wire back for you and an auger clears chips better; the bell hanger vs flex bit guide and the ship auger guide own those. The long twist drill is for the steel in the way: a steel stud, a hollow metal door frame, strut behind the drywall, a lintel, a bracket, a tank.

How do you drill straight with a long bit without snapping it?

A long drill bit snaps because it flexes, and flex grows with the cube of the length sticking out of the chuck. A 1/4 in. bit with 17 in. out flexes about 180 times as much as the same bit with 3 in. out. Spin it free in the air and it whips; lean on it at an angle and it arcs; let the chips pack and it twists off. The fix is support at every step.

• Start with the matching jobber. Drill the first 2 in. with a jobber of the same diameter (012516 at 1/4 in., $3.24). The short bit sets the angle; the long bit follows it.

• Put the long bit in the hole before you pull the trigger. The pilot hole holds the tip, so there is no whip.

• Low gear until the bit is an inch in, then the starting speed for the metal from the drill speed chart: about 1,400 RPM for 1/4 in. in mild steel, 600 in stainless.

• Light feed, square to the work. Sight a square beside the bit, or clamp a block with a straight hole over the mark as a guide. The weight of the drill is enough pressure.

• Peck. Forward about an inch, back out, clear the chips. A reach bit's flutes are only 2-3/4 in. long; nothing carries chips out of a deep hole but you.

• Oil every hole in steel. A dry long bit blues at the tip first and loses its edge there.

Buy the pilot with the long bit. A 1/4 x 18 in. bit and its jobber pilot together are $17.73, and the pilot is the part that keeps the long bit alive.

Which length does your trade actually use?

Two rows of this table are duct work, and HVAC crews should read them the same way: a stubby for the sheet metal, a 6 in. cobalt aircraft drill when the stainless is behind a flange. For holes bigger than 1/2 in. in sheet, a step drill is the tool.

Is a drill bit extension the same as a long drill bit?

No. A drill bit extension is a hex shaft with a holder on the end that carries a short bit; a long drill bit is one piece of steel. The extension works when the hole is wider than its holder, which is why it pairs well with spade bits, augers and hole saws. For a twist drill the holder is wider than the hole, so the extension stops at the surface, and the joint adds wobble that a 1/4 in. bit does not forgive. For a small hole through something thick or far away, buy the length. For a 3/4 in. hole through studs with a spade or an auger, an extension is the economical choice, and the spade bit vs auger bit guide covers those. If the extension you were searching for is for a rotary hammer, that is an SDS-Max extension, a different product again.

Which length should you buy? The picks by situation

One row per job, 1/4 in. unless noted, store prices on Nov 4, 2026. Every bit is made in the USA.

Browse by length: jobber, stubby and mechanics, 6 and 12 in. aircraft extension, 18 in. and up.

Not sure which length you need? Call our team at (833) 4-ETOOLS or email sales@eldoradotools.com with the hole size, how deep it is, and what is in the way.

Sources: Triumph Twist Drill and Tru-Cut product specifications; Tru-Cut on extension-drill flute lengths (Nov 2026); NAS 907 aircraft drill dimensions; our 12-month order records.

First published [date], with prices checked in our catalog on Nov 4, 2026.