Ship auger bit sizes: diameter x length chart
A ship auger bit is the deep-hole wood borer of the electrical and utility trades: a single-flute auger with a self-feeding screw point and a hex shank for a drill or impact driver, built to bore studs, poles, and timbers in one pass [1][5]. The name survives from shipbuilding, where the same single-flute pattern bored mast and keel timber; the modern catalog version runs 1/4 to 1-3/4 in cutting diameter across 6, 8, 18, 24, and 30 in length classes [1][3][4]. This chart assembles the size matrix from the manufacturer and dealer tables that actually stock these bits, with part numbers, the hex shank rule that trips up extension buyers, and the nail-rated lines electricians should be choosing. If you are looking at the square-shank hand-brace version of the same pattern, that is a different tool family covered on our auger bit sizes page.
The size grid at a glance
Four numbers define a ship auger bit, and the catalogs hold them remarkably still across brands [1][4][5]:
| Spec | Standard values | Notes |
|---|---|---|
| Cutting diameter | 1/4 to 1-3/4 in | 1/16 steps for most of the range; the 18 in class is the most complete ladder [1][3] |
| Overall length | 6, 7-1/2, 8, 18, 24, 30 in | plus 36/48/60/72 in extended special-order classes for timber work [1][2] |
| Flute length | 4 in (6 in class), 5 in (7-1/2), 6 in (8), 15 in (18) | flute sets the usable hole depth; shank and lead screw take up the rest [1][5] |
| Hex shank | 5/16 in or 7/16 in | 5/16 common on 1/4 to 1/2 in diameters (imports, Milwaukee); 7/16 on 9/16 in and larger, and across whole ICS/Irwin/Wood Owl lines [1][3][8] |
Two reading notes before the tables. Retail box-store lines often run 17 in overall rather than 18 (Irwin WeldTec, DeWalt, Bosch Nailkiller), which is the same class with an inch trimmed, not a different tool [9][10]. And the diameter x length combinations are not a full grid: short classes skip small diameters at some makers and long classes skip large ones at others, so the matrix below marks what each catalog actually sells.
Full matrix: diameter x length x shank
Every row below is taken from a live manufacturer or dealer table pulled for this chart, and the matrix cell names whose catalog sells that combination. Two independent surfaces back the rows where the sources overlap; single-surface cells are marked in the notes column [1][3][4][5].
| Diameter (in) | 6 in class | 7-1/2 in class | 8 in class | 18 in class | 24 / 30 in | Hex shank | Sources |
|---|---|---|---|---|---|---|---|
| 1/4 | not listed | Irwin 49904, Greenlee 61PTS | A14-8 (C&E) | A14-18 (C&E) | not listed | 5/16 (C&E rule) | [3][4] |
| 5/16 | not listed | Irwin 49905, Greenlee 61PTS | A516-8 (C&E) | A516-18 (C&E) | not listed | 5/16 (C&E rule) | [3][4] |
| 3/8 | not listed | WoodOwl 02703/03703/09703; Irwin 49906 | A38-8 (C&E) | ICS SAB18L024; WoodOwl 02803/03803/09803; Irwin 47906 | not listed | 7/16 (ICS, WoodOwl); 5/16 (C&E rule) | [1][3][4] |
| 7/16 | not listed | WoodOwl 02704/03704/09704; Irwin 49907 | A716-8 (C&E) | ICS SAB18L028; WoodOwl 02804/03804/09804 | not listed | 7/16 (ICS, WoodOwl) | [1][3][4] |
| 1/2 | ICS SAB06L032 | WoodOwl 02705/03705/09705; Irwin 49908 | A12-8 (C&E) | ICS SAB18L032; WoodOwl 02805/03805/09805; Ideal 35-820; C&E A12-18 | A12-24 (C&E) | 7/16 (ICS, Ideal, WoodOwl); 5/16 (C&E, Milwaukee 48-13-5540) | [1][3][4][5][6] |
| 9/16 | ICS SAB06L036 | WoodOwl 02706/03706/09706; Irwin 49909 | not listed | ICS SAB18L036; WoodOwl 02806/03806/09806; C&E A916-18 | A916-24 (C&E) | 7/16 (all listed) | [1][3][4] |
| 5/8 | ICS SAB06L040 | WoodOwl 02707/03707/09707; Irwin 49910; Ideal 35-810 | A58-8 (C&E) | ICS SAB18L040; WoodOwl 02807/03807/09807; Ideal 35-821; C&E A58-18 | A58-24, A58-30 (C&E) | 7/16 (all listed) | [1][3][4][5] |
| 11/16 | ICS SAB06L044 | WoodOwl 02708/03708/09708; Irwin 49911; Ideal 35-811 | ICS SAB08L044; A1116-8 (C&E) | ICS SAB18L044; WoodOwl 02808/03808/09808; Ideal 35-822; C&E A1116-18 | A1116-24, A1116-30 (C&E) | 7/16 (all listed) | [1][3][4][5] |
| 3/4 | ICS SAB06L048 | WoodOwl 02709/03709/09709; Irwin 49912; Ideal 35-812 | ICS SAB08L048; A34-8 (C&E) | ICS SAB18L048; WoodOwl 02809/03809/09809; Ideal 35-823; C&E A34-18 | A34-24, A34-30 (C&E) | 7/16 (all listed) | [1][3][4][5] |
| 13/16 | ICS SAB06L052 | WoodOwl 02710/03710/09710; Irwin 49913; Ideal 35-813 | ICS SAB08L052 | ICS SAB18L052; WoodOwl 02810/03810/09810; Ideal 35-824; C&E A1316-18 | A1316-24, A1316-30 (C&E) | 7/16 (all listed) | [1][3][4][5] |
| 7/8 | ICS SAB06L056 | WoodOwl 02711/03711/09711; Irwin 49914; Ideal 35-814 | ICS SAB08L056; A78-8 (C&E) | ICS SAB18L056; WoodOwl 02811/03811/09811; Ideal 35-825; C&E A78-18 | not listed | 7/16 (all listed) | [1][3][4][5] |
| 15/16 | ICS SAB06L060 | WoodOwl 02712/03712/09712; Irwin 49915; Ideal 35-815 | ICS SAB08L060 | ICS SAB18L060; WoodOwl 02812/03812/09812; Ideal 35-826; C&E A1516-18 | not listed | 7/16 (all listed) | [1][3][4][5] |
| 1 | ICS SAB06L100 | WoodOwl 02713/03713/09713; Irwin 49916; Ideal 35-815 | ICS SAB08L100; A1-8 (C&E) | ICS SAB18L100; WoodOwl 02813/03813/09813; Ideal 35-827; C&E A1-18 | A1-24, A1-30 (C&E) | 7/16 (all listed) | [1][3][4][5] |
| 1-1/16 | not listed | not listed | not listed | ICS SAB18L104; WoodOwl 02814 (18 in class) | not listed | 7/16 | [1][3] |
| 1-1/8 | ICS SAB06L108 | WoodOwl 02715/03715/09715; Irwin 49918; Ideal 35-816 | ICS SAB08L108; A118-8 (C&E) | ICS SAB18L108; WoodOwl 02815/03815/09815; Ideal 35-828; C&E A118-18 | A118-24, A118-30 (C&E) | 7/16 (all listed) | [1][3][4][5] |
| 1-1/4 | ICS SAB06L116 | WoodOwl 02717/03717/09717; Irwin 49920; Ideal 35-817 | ICS SAB08L116; A114-8 (C&E) | ICS SAB18L116; WoodOwl 02817/03817/09817; Ideal 35-829; C&E A114-18 | A114-24, A114-30 (C&E) | 7/16 (all listed) | [1][3][4][5] |
| 1-3/8 | ICS SAB06L124 | WoodOwl 02718/03718/09718; Irwin 49924 | ICS SAB08L124; A138-8 (C&E) | ICS SAB18L124; WoodOwl 02818/03818/09818; C&E A138-18 | A138-30 (C&E) | 7/16 (all listed) | [1][3][4] |
| 1-1/2 | ICS SAB06L132 | WoodOwl 02719/03719/09719; Irwin 49926 | ICS SAB08L132 | ICS SAB18L132; WoodOwl 02819/03819/09819; C&E A112-18 | A112-24, A112-30 (C&E) | 7/16 (all listed) | [1][3][4] |
| 1-3/4 | not listed | not listed | not listed | C&E A134-18 | not listed | 7/16 (over 9/16 rule) | [4] |
Reading the matrix honestly: the 1-3/4 x 18 cell rests on a single dealer surface (C&E A134-18) and no manufacturer catalog surveyed here lists that diameter; treat it as a specialty order, not a shelf size. The 1-1/16 diameter exists almost nowhere except ICS (SAB18L104) and Wood Owl's 18 in class, an odd 1/16 step between 1 and 1-1/8 that most buyers should skip. And note the 8 in class at ICS starts at 11/16, not 3/8: short bits in small diameters come from the 7-1/2 in Wood Owl or 8 in C&E classes instead [1][4].
The shank rule, and the trap in it
Construction & Electrical prints the rule in one line above its 50-row table: 5/16 in hex shank for 1/4 through 1/2 in diameters, 7/16 in hex shank for 9/16 in and larger [4]. That matches the ICS catalog, whose entire SAB matrix from 3/8 to 1-1/2 in carries a 7/16 in quick-release hex shank [1], and Ideal's Power Ship Auger spec block: 7/16 in shank on both the 7-1/2 in and 18 in classes [5].
Here is the trap. The rule reads like a size split, but it is really a brand split at the small diameters. Milwaukee's 1/2 x 18 ship auger (48-13-5540) carries a 5/16 in quick-change hex shank [6], and so do the C&E import A-series bits from 1/4 to 1/2 in [4]. But ICS, Irwin WeldTec (7/16 in shank across the family, 3/8 in diameter on up), Wood Owl (7/16 in quick-change across every line), and Ideal all run 7/16 in shanks even at 3/8 and 1/2 in cutting diameter [1][5][7][8]. So two bits with identical size printed on the box can need different extensions. The one thing that is consistent: nothing in the category exceeds 7/16 in, so every ship auger on this page fits the 1/2 in chuck on an ordinary drill, with the hex shank meaning it also clicks into a quick-change holder or impact driver.
For electricians: stud bays, the 4-3/4 in Mini, and extensions
The electrical use case is why the short classes exist. An 18 in ship auger reaches through a top plate or a double stud in one pass, but it cannot run inside a finished wall cavity: standard framing at 16 in on center leaves a 14-1/2 in clear bay, and a full-size drill with an 18 in bit does not fit between the drywall. That is the job Ideal's Mini Auger exists for: 4-3/4 in overall, 2-1/2 in of twist, 5/8 to 1 in diameters (35-862 to 35-868), 7/16 in shank, and catalog copy that says it outright: designed to fit between wall studs with common drills, eliminating the need for expensive right-angle drills [5]. For wire holes in framing, the diameter logic is the same as on our bell hanger bit chart: a single 14/2 or 12/2 cable needs a small clean hole, multiple cables or a connector need 3/4 in and up, and boring keeps 1-1/4 in back from the stud face (nail plates where it cannot), because drywall screws and trim nails are the enemy of the cable you just pulled.
Extensions are where the shank rule bites. Ship auger extensions come in the same two hex sizes as the bits: Ideal's 18 in extensions are 5/16 in (35-818) and 7/16 in (35-819), six flats for the chuck with an Allen-head set screw locking the bit [5]. Buy the extension that matches the shank of the bit you own, not the diameter class it came from: a 1/2 in Milwaukee bit (5/16 shank) will sit loose in a 7/16 extension, and a 1/2 in Ideal bit (7/16 shank) will not enter a 5/16 one at all. For distances beyond what an 18 in bit plus 18 in extension covers, the flexible shaft installer bits on our flex bit sizes page cover the 18 to 72 in ranges through finished walls.
Nail-rated vs standard ship augers
Remodel and rewiring work means nail-embedded wood, and the category splits cleanly on whether the cutting edge survives it. The nail-rated lines, each with first-party claims: Irwin WeldTec welds a harder HSS cutting edge to the body, with twice the nail-cutting life of standard ship augers, 7/16 in quick-change shank, 17 in class from 3/8 to 1-5/8 in [9]; Bosch Nailkiller, 3/8 to 1 in x 17 in, reinforced tip with dual cutting edges tested against Irwin Speedbor and Milwaukee [10]; Wood Owl Tri-Cut Nail Chipper (037xx/038xx), the three-edge version built to chip through nails [3]; and Ideal RESI-MASTER, dual-helix twin cutting edges sold explicitly for drilling through nail-embedded timbers, in 7-1/2 and 18 in classes [5]. The standard lines, including ICS SAB and Wood Owl Standard (single cutting edge, single flute), are utility-pole and timber borers with no nail claim; a hidden nail can chip the cutter. The price gap between the classes is a few dollars at any given size, so the honest guidance is: if the wall is closed and you cannot see what is in the stud, buy the nail-rated line in the same size row above.
Buying by length class
| Length class | Flute / usable depth | What it is for | Representative lines |
|---|---|---|---|
| 6 in | 4 in flute | pocket holes in tight assemblies, work between joists | ICS SAB06 (1/2 to 1-1/2) |
| 7-1/2 in | 5 in twist | general boring, tighter stud work; Irwin's classic 49900 series length | WoodOwl 027xx/037xx/097xx, Ideal 35-81x, Irwin 499xx |
| 8 in | 6 in flute | same class one inch longer; import dealer standard | ICS SAB08 (11/16 to 1-1/2), C&E A-x-8 |
| 17 in (retail) | about 12 in flute | box-store through-stud class; same use as 18 in | Irwin WeldTec 3043004 class, DeWalt DW1680-DW1692, Bosch Nailkiller |
| 18 in | 15 in flute | the electrician standard: through top plates and doubled framing | ICS SAB18, Ideal 35-82x, WoodOwl 028xx/038xx/098xx, C&E A-x-18 |
| 24 / 30 in | long flute | through multiple members, deep timber | C&E A-x-24, A-x-30 |
| 36 / 48 / 60 / 72 in | extended | retaining-wall tiebacks, utility pole crossbolts; made 1/16 in over the rod size | ICS SAB36/48/60/72, PPB23 power pole bits [2] |
The extended-length note is worth keeping if you ever anchor timber: ICS makes the 48 to 72 in ship augers 1/16 in larger than the threaded rod they pair with, so a 3/4 in rod gets a 13/16 in auger, per their own retaining-wall spec [2].
Related guides
Also on this site: auger bit sizes for the hand-brace and traditional auger families (Jennings-pattern and the square-taper shank world, a different animal from these power hex-shank bits), bell hanger bit sizes for the wire-pulling bits with a fish eye, flex bit sizes for the flexible shaft versions that reach through finished walls, and spade bit sizes for the fast flat alternative in thin material. For the big-diameter question above 1-3/4 in in metal or wood, the silver and deming chart covers the reduced-shank twist drill pattern.
Sources
- ICS Cutting Tools, catalog page 174 (PDF, pulled live 2026-09-22): Ship Auger Bits 6 in (SAB06L032-132, 4 in flute), 8 in (SAB08L044-132, 6 in flute), 18 in (SAB18L024-132, 15 in flute), all 7/16 in hex shank, single flute, medium screw point: icscuttingtools.com
- ICS Cutting Tools, catalog page 175 (PDF, pulled live 2026-09-22): extended length 48/60/72 in ship augers made 1/16 in over rod size, power pole bits PPB23L series, hand brace utility pole augers: icscuttingtools.com
- WoodOwl (Star-M), Cross-Reference Chart (pulled live 2026-09-22): full 7-1/2 in and 18 in ship auger diameter ladders x Irwin/Magbit/Greenlee/Lenox/WoodOwl Standard 02xxx, Nail Chipper 03xxx, Ultra Smooth 09xxx part numbers: woodowl.com
- Construction & Electrical Products, Ship Auger Bits dealer table (pulled live 2026-09-22): 50-row A-series matrix 1/4 to 1-3/4 in x 8/18/24/30 in with prices; printed shank rule 5/16 in for 1/4 to 1/2 in, 7/16 in for 9/16 in and larger: constructionandelectrical.com
- Ideal Industries auger catalog pages (via Kirby Risk asset PDF, pulled live 2026-09-22): Power Ship Augers 7-1/2 in (35-810 to 35-817) and 18 in (35-820 to 35-829), all 7/16 in shank; Mini Augers 4-3/4 in (35-862 to 35-868) designed to fit between wall studs; Installer Bits 35-870 to 35-872; Auger Bit Extensions 18 in, 5/16 in (35-818) and 7/16 in (35-819); RESI-MASTER dual-helix nail-embedded-timber augers 35-892 to 35-899, 35-971 to 35-979: kirbyrisk.com
- Construction Tool Warehouse, Milwaukee 48-13-5540 listing: 1/2 in diameter, 18 in overall, 15 in flute, 5/16 in quick-change hex shank: constructiontoolwarehouse.com
- Hardwick & Sons, Wood Owl Tri-Cut Ultra Smooth 18 in listing (pulled live 2026-09-22): 7/16 in quick change shank, 18 in class diameter table 3/8 to 1-1/2 in with model numbers 09803 to 09819: hardwickandsons.com
- Timber Frame HQ, Wood Owl Ultra Smooth Ship Augers: 7/16 in quick-change shank on both 18 and 7-1/2 in lengths, diameter list 3/4 to 1-1/2 in plus 12mm: timberframehq.com
- Irwin WeldTec ship auger listings (pulled live 2026-09-22): 3043011 7/8 x 17 with 7/16 in quick-change hex shank (Ace Hardware 2238236); 1773957 1-5/8 x 17, 17 in OAL, 12 in flute, 7/16 in shank, welded HSS edge, 2x nail cutting life (Mallory, Acme Tools): acehardware.com, mallory.com
- ACE Tools, Class 18 Power Ship Auger / Nailkiller catalog (PDF): Bosch Nailkiller ASHLB06-ASHLB16, 3/8 to 1 in x 17 in, tested against Irwin Speedbore and Milwaukee; DeWalt Power Ship Auger family DW1680-DW1692, 9/16 to 1-1/2 in x 17 in: acetools.com, dewalt.com