# Slotted and castle nuts, inch (ASME B18.2.2): hex slotted 1/4 to 2 in, castle 1/4 to 1-1/4 in — across flats, height, slot width, cotter hole + envelope models

> What are the dimensions of a 3/8 or 1/2 inch slotted (castle) nut, and what cotter pin goes with it?

- Category: Hardware › Fasteners
- Kind: Standard part
- Basis: AFT Fasteners' ASME B18.2.2 hex slotted nut and castle nut tables (Engineers Edge and a Shopify-hosted castle sheet as cross-checks), McMaster-Carr's slotted-nut table for the cotter pin hole; eight envelope models as files
- Page: https://xemstudio.com/objects/slotted-castle-nuts-inch-asme-b18-2-2/ · JSON: https://xemstudio.com/api/geometry?object=slotted-castle-nuts-inch-asme-b18-2-2 · Plain text: https://xemstudio.com/objects/slotted-castle-nuts-inch-asme-b18-2-2/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); files CC BY 4.0 or their publisher's license
- Use in every chat: add https://xemstudio.com/mcp as a connector (https://xemstudio.com/use-with-ai/)

## Overall (mm)

| length | width | height |
|---|---|---|
| 12.8 | 11.1 | 5.6 |

**Exact dimensions.** Every file is drawn at true size with no tolerance added. The holes and pins that meet another part are listed below under Mating features, with the fit each joint needs; open those by your process's clearance before making the part.

## Notes

- Hex slotted nuts (AFT, citing ANSI / ASME B18.2.2), inches, 1/4 to 2: width across flats F (basic, then max / min), width across corners G max / min, thickness H (basic, then max / min), unslotted thickness T (max / min), slot width S (max / min). AFT's flattened table was read by header order, so check the standard if a figure matters. Engineers Edge prints the same F, H (as a decimal), T and S for the sizes it lists (1/4 and 3/4 to 1-1/2 read). Threads UNC, UNF or 8UN; steel nuts to ASTM A563 grade A or SAE J995 grade 2 unless specified (Engineers Edge).
- Hex castle nuts (AFT, ANSI B18.2.2-1970 column, 1/4 to 1-1/4): the slots are cut in a cylinder whose diameter W (minimum) is a little under the hex width, with a fillet R at its base. T is the height of the hex part (basic, then max / min). The AFT page labels its last castle row '1-1/4' but prints a major diameter of 1.1250 beside it; the row's F of 1-7/8 matches the 1-1/4 slotted nut, so it is shown as 1-1/4. The castle slot widths equal the slotted-nut S for the same size. A Shopify-hosted castle sheet prints the same numbers with other column labels. AFT says the castle values for Grade 5 nuts are recommendations, not an industry norm.
- Cotter pin hole diameter per McMaster-Carr (inches): Grade 5 slotted nuts and, separately, low-strength steel slotted nuts differ from 7/16 up (for example 1/2: 7/64 and 1/8; 7/8: 3/16 and 5/32; 1-1/4: 5/16 and 9/32). Both are shown; use the pin hole of the nut you buy. McMaster's Grade 5 heights differ from AFT's basic H in two places: 7/8 (McMaster 49/64, AFT basic 3/4; McMaster's low-strength nut is 3/4) and 1-1/4 (McMaster 1-3/32 = 1.094, AFT basic 1-1/16, AFT max 1.094); AFT's max / min brackets both values.
- Files are Xem-drawn envelopes: hex at the basic width across flats and basic height, six slots (three straight cuts 60° apart) of the maximum published slot width S to the unslotted thickness (slotted nuts: T max, castle nuts: T basic); the castle collar is a plain cylinder at W min. The bore is a plain cylinder at the nominal thread major diameter; no chamfer, no washer face, no fillet R. Sizes drawn: slotted 1/4, 3/8, 1/2, 5/8, 3/4; castle 1/4, 1/2, 3/4.
- McMaster-Carr sells slotted hex nuts and castellated nuts with per-part STEP; the categories are linked, not copied. Metric: slotted-castle-nuts-din-935.

## Mating features (exact size; open press / slide / run / socket by your process clearance, leave designed and clamp as drawn)

| feature | exact | mates with | fit | files |
|---|---|---|---|---|
| bore (thread as plain cylinder) | 1/4 to 3/4 in: Ø6.35, 9.525, 12.7, 15.875, 19.05 mm (thread major) | bolt of the same thread (plain cylinder at the major Ø) | designed | hex-* |
| six slots | S max: 1/4 0.10, 3/8 0.15, 1/2 0.18, 5/8 0.24, 3/4 0.24 in | cotter pin hole (McMaster, Grade 5 slotted nut): 1/4 1/16, 3/8 7/64, 1/2 7/64, 5/8 5/32, 3/4 5/32 in | slide | hex-* |
| hex body | F basic: 1/4 7/16, 3/8 9/16, 1/2 3/4, 5/8 15/16, 3/4 1-1/8 in | hex pocket or wrench: width = F | slide | hex-* |

## Sizes

| type | size (in) | F basic | F max / min | G max / min | H basic | H max / min | T (unslotted thickness) | S slot width max / min | W min (castle collar dia) | R (castle fillet) | cotter pin hole, Grade 5 (McMaster, in) | cotter pin hole, low-strength (McMaster, in) |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| hex slotted nut (ASME B18.2.2) | 1/4 | 7/16 | 0.438 / 0.428 | 0.505 / 0.488 | 7/32 | 0.226 / 0.212 | 0.14 / 0.12 | 0.10 / 0.07 | — | — | 1/16 | 1/16 |
| hex slotted nut (ASME B18.2.2) | 5/16 | 1/2 | 0.500 / 0.489 | 0.577 / 0.557 | 17/64 | 0.273 / 0.258 | 0.18 / 0.16 | 0.12 / 0.09 | — | — | 5/64 | 5/64 |
| hex slotted nut (ASME B18.2.2) | 3/8 | 9/16 | 0.562 / 0.551 | 0.650 / 0.628 | 21/64 | 0.337 / 0.320 | 0.21 / 0.19 | 0.15 / 0.12 | — | — | 7/64 | 7/64 |
| hex slotted nut (ASME B18.2.2) | 7/16 | 11/16 | 0.688 / 0.675 | 0.794 / 0.768 | 3/8 | 0.385 / 0.365 | 0.23 / 0.21 | 0.15 / 0.12 | — | — | 7/64 | 3/32 |
| hex slotted nut (ASME B18.2.2) | 1/2 | 3/4 | 0.750 / 0.736 | 0.866 / 0.840 | 7/16 | 0.448 / 0.427 | 0.29 / 0.27 | 0.18 / 0.15 | — | — | 7/64 | 1/8 |
| hex slotted nut (ASME B18.2.2) | 9/16 | 7/8 | 0.875 / 0.861 | 1.010 / 0.982 | 31/64 | 0.496 / 0.473 | 0.31 / 0.29 | 0.18 / 0.15 | — | — | 9/64 | 7/64 |
| hex slotted nut (ASME B18.2.2) | 5/8 | 15/16 | 0.938 / 0.922 | 1.083 / 1.051 | 35/64 | 0.559 / 0.535 | 0.34 / 0.32 | 0.24 / 0.18 | — | — | 5/32 | 5/32 |
| hex slotted nut (ASME B18.2.2) | 3/4 | 1-1/8 | 1.125 / 1.088 | 1.299 / 1.240 | 41/64 | 0.665 / 0.617 | 0.40 / 0.38 | 0.24 / 0.18 | — | — | 5/32 | 5/32 |
| hex slotted nut (ASME B18.2.2) | 7/8 | 1-5/16 | 1.312 / 1.269 | 1.516 / 1.447 | 3/4 | 0.776 / 0.724 | 0.52 / 0.49 | 0.24 / 0.18 | — | — | 3/16 | 5/32 |
| hex slotted nut (ASME B18.2.2) | 1 | 1-1/2 | 1.500 / 1.450 | 1.732 / 1.653 | 55/64 | 0.887 / 0.831 | 0.59 / 0.56 | 0.30 / 0.24 | — | — | 3/16 | 3/16 |
| hex slotted nut (ASME B18.2.2) | 1-1/8 | 1-11/16 | 1.688 / 1.631 | 1.949 / 1.859 | 31/32 | 0.999 / 0.939 | 0.64 / 0.61 | 0.33 / 0.24 | — | — | — | — |
| hex slotted nut (ASME B18.2.2) | 1-1/4 | 1-7/8 | 1.875 / 1.812 | 2.165 / 2.066 | 1-1/16 | 1.094 / 1.030 | 0.70 / 0.67 | 0.40 / 0.31 | — | — | 5/16 | 9/32 |
| hex slotted nut (ASME B18.2.2) | 1-3/8 | 2-1/16 | 2.062 / 1.994 | 2.382 / 2.273 | 1-11/64 | 1.206 / 1.138 | 0.82 / 0.78 | 0.40 / 0.31 | — | — | — | — |
| hex slotted nut (ASME B18.2.2) | 1-1/2 | 2-1/4 | 2.250 / 2.175 | 2.598 / 2.480 | 1-9/32 | 1.317 / 1.245 | 0.86 / 0.82 | 0.46 / 0.37 | — | — | — | 5/16 |
| hex slotted nut (ASME B18.2.2) | 2 | 3 | 3.000 / 2.900 | 3.464 / 3.306 | 1-23/32 | 1.759 / 1.679 | 1.24 / 1.20 | 0.52 / 0.43 | — | — | — | 3/8 |
| hex castle nut (ANSI B18.2.2-1970) | 1/4 | 7/16 | 0.438 / 0.428 | 0.505 / 0.488 | 9/32 | 0.288 / 0.274 | 3/16 (max 0.20 / min 0.18) | 0.10 / 0.07 | 0.371 | 0.094 | 1/16 | 1/16 |
| hex castle nut (ANSI B18.2.2-1970) | 5/16 | 1/2 | 0.500 / 0.489 | 0.577 / 0.557 | 21/64 | 0.336 / 0.320 | 15/64 (max 0.24 / min 0.22) | 0.12 / 0.09 | 0.425 | 0.094 | 5/64 | 5/64 |
| hex castle nut (ANSI B18.2.2-1970) | 3/8 | 9/16 | 0.562 / 0.551 | 0.650 / 0.628 | 13/32 | 0.415 / 0.398 | 9/32 (max 0.29 / min 0.27) | 0.15 / 0.12 | 0.478 | 0.094 | 7/64 | 7/64 |
| hex castle nut (ANSI B18.2.2-1970) | 7/16 | 11/16 | 0.688 / 0.675 | 0.794 / 0.768 | 29/64 | 0.463 / 0.444 | 19/64 (max 0.31 / min 0.29) | 0.15 / 0.12 | 0.582 | 0.094 | 7/64 | 3/32 |
| hex castle nut (ANSI B18.2.2-1970) | 1/2 | 3/4 | 0.750 / 0.736 | 0.866 / 0.840 | 9/16 | 0.573 / 0.552 | 13/32 (max 0.42 / min 0.40) | 0.18 / 0.15 | 0.637 | 0.125 | 7/64 | 1/8 |
| hex castle nut (ANSI B18.2.2-1970) | 9/16 | 7/8 | 0.875 / 0.861 | 1.010 / 0.982 | 39/64 | 0.621 / 0.598 | 27/64 (max 0.43 / min 0.41) | 0.18 / 0.15 | 0.744 | 0.156 | 9/64 | 7/64 |
| hex castle nut (ANSI B18.2.2-1970) | 5/8 | 15/16 | 0.938 / 0.922 | 1.083 / 1.051 | 23/32 | 0.731 / 0.706 | 1/2 (max 0.51 / min 0.49) | 0.24 / 0.18 | 0.797 | 0.156 | 5/32 | 5/32 |
| hex castle nut (ANSI B18.2.2-1970) | 3/4 | 1-1/8 | 1.125 / 1.088 | 1.299 / 1.240 | 13/16 | 0.827 / 0.798 | 9/16 (max 0.57 / min 0.55) | 0.24 / 0.18 | 0.941 | 0.188 | 5/32 | 5/32 |
| hex castle nut (ANSI B18.2.2-1970) | 7/8 | 1-5/16 | 1.312 / 1.269 | 1.516 / 1.447 | 29/32 | 0.922 / 0.890 | 21/32 (max 0.67 / min 0.64) | 0.24 / 0.18 | 1.097 | 0.188 | 3/16 | 5/32 |
| hex castle nut (ANSI B18.2.2-1970) | 1 | 1-1/2 | 1.500 / 1.450 | 1.732 / 1.653 | 1 | 1.018 / 0.982 | 23/32 (max 0.73 / min 0.70) | 0.30 / 0.24 | 1.254 | 0.188 | 3/16 | 3/16 |
| hex castle nut (ANSI B18.2.2-1970) | 1-1/4 | 1-7/8 | 1.875 / 1.812 | 2.165 / 2.066 | 1-1/4 | 1.272 / 1.228 | 7/8 (max 0.89 / min 0.86) | 0.40 / 0.31 | 1.570 | 0.250 | 5/16 | 9/32 |

## Where the files are

- AFT Fasteners: [Hex slotted nuts, ANSI / ASME B18.2.2: F, G, H, T, S, FIM max / min per size 1/4 to 2](https://www.aftfasteners.com/hex-slotted-nuts-technical-information/) — web — Maker / distributor reference; numbers only. The page table is flattened; columns follow its header order
- Engineers Edge: [Slotted hex nut dimensions (ASME B18.2.2): basic thread dia, F flat width, H thickness, T unslotted thickness, S slot width (1/4, 3/4 to 1-1/2 read)](https://ns2.engineersedge.com/slotted_hex_nut.htm) — web — Reference page; numbers only
- AFT Fasteners: [Hex castle nuts, ANSI B18.2.2 (1970): F, G, H, T, S, R, W min, FIR per size 1/4 to 1-1/4](https://aftfasteners.com/hex-castle-nuts-technical-information) — web — Maker / distributor reference; numbers only
- Castle nut sheet (hosted on a Shopify CDN, maker not named in the text read): [Castle nuts, ANSI B18.2.2 (1970): same values as the AFT table with other column labels](https://cdn2.shopify.com/s/files/1/0056/7856/3437/files/Nutscastle.pdf) — web — Maker datasheet; numbers only
- McMaster-Carr: [Slotted hex nuts (inch and metric, cotter pin diameter per size) (free STEP/IGES per part, for your own design use; no redistribution)](https://www.mcmaster.com/slotted-hex-nuts) — STEP, IGES, PDF — McMaster-Carr site terms: personal design use, no redistribution (verify at link)
- McMaster-Carr: [Castellated nuts (free STEP/IGES per part, for your own design use; no redistribution)](https://www.mcmaster.com/castellated-nuts) — STEP, IGES, PDF — McMaster-Carr site terms: personal design use, no redistribution (verify at link)

## Free STEP/STL (8 parts, CC BY 4.0, Xem Studio)

Index: https://xemstudio.com/files/hardware/slotted-castle-nuts-inch-asme-b18-2-2/index.json

- hex-slotted-nut-1-4-envelope: [STEP](https://xemstudio.com/files/hardware/slotted-castle-nuts-inch-asme-b18-2-2/hex-slotted-nut-1-4-envelope.step) · [STL](https://xemstudio.com/files/hardware/slotted-castle-nuts-inch-asme-b18-2-2/hex-slotted-nut-1-4-envelope.stl) — 1/4 hex slotted nut envelope: hex 7/16 in across flats (basic) × 7/32 in high (H basic), six slots 0.10 in wide (S max) to the unslotted thickness T max 0.14 in (slot depth 2.00 mm), bore Ø6.35 mm (1/4 in thread major diameter as a plain cylinder); no chamfers, thread or washer face
- hex-slotted-nut-3-8-envelope: [STEP](https://xemstudio.com/files/hardware/slotted-castle-nuts-inch-asme-b18-2-2/hex-slotted-nut-3-8-envelope.step) · [STL](https://xemstudio.com/files/hardware/slotted-castle-nuts-inch-asme-b18-2-2/hex-slotted-nut-3-8-envelope.stl) — 3/8 hex slotted nut envelope: hex 9/16 in across flats (basic) × 21/64 in high (H basic), six slots 0.15 in wide (S max) to the unslotted thickness T max 0.21 in (slot depth 3.00 mm), bore Ø9.52 mm (3/8 in thread major diameter as a plain cylinder); no chamfers, thread or washer face
- hex-slotted-nut-1-2-envelope: [STEP](https://xemstudio.com/files/hardware/slotted-castle-nuts-inch-asme-b18-2-2/hex-slotted-nut-1-2-envelope.step) · [STL](https://xemstudio.com/files/hardware/slotted-castle-nuts-inch-asme-b18-2-2/hex-slotted-nut-1-2-envelope.stl) — 1/2 hex slotted nut envelope: hex 3/4 in across flats (basic) × 7/16 in high (H basic), six slots 0.18 in wide (S max) to the unslotted thickness T max 0.29 in (slot depth 3.75 mm), bore Ø12.70 mm (1/2 in thread major diameter as a plain cylinder); no chamfers, thread or washer face
- hex-slotted-nut-5-8-envelope: [STEP](https://xemstudio.com/files/hardware/slotted-castle-nuts-inch-asme-b18-2-2/hex-slotted-nut-5-8-envelope.step) · [STL](https://xemstudio.com/files/hardware/slotted-castle-nuts-inch-asme-b18-2-2/hex-slotted-nut-5-8-envelope.stl) — 5/8 hex slotted nut envelope: hex 15/16 in across flats (basic) × 35/64 in high (H basic), six slots 0.24 in wide (S max) to the unslotted thickness T max 0.34 in (slot depth 5.25 mm), bore Ø15.88 mm (5/8 in thread major diameter as a plain cylinder); no chamfers, thread or washer face
- hex-slotted-nut-3-4-envelope: [STEP](https://xemstudio.com/files/hardware/slotted-castle-nuts-inch-asme-b18-2-2/hex-slotted-nut-3-4-envelope.step) · [STL](https://xemstudio.com/files/hardware/slotted-castle-nuts-inch-asme-b18-2-2/hex-slotted-nut-3-4-envelope.stl) — 3/4 hex slotted nut envelope: hex 1-1/8 in across flats (basic) × 41/64 in high (H basic), six slots 0.24 in wide (S max) to the unslotted thickness T max 0.40 in (slot depth 6.11 mm), bore Ø19.05 mm (3/4 in thread major diameter as a plain cylinder); no chamfers, thread or washer face
- hex-castle-nut-1-4-envelope: [STEP](https://xemstudio.com/files/hardware/slotted-castle-nuts-inch-asme-b18-2-2/hex-castle-nut-1-4-envelope.step) · [STL](https://xemstudio.com/files/hardware/slotted-castle-nuts-inch-asme-b18-2-2/hex-castle-nut-1-4-envelope.stl) — 1/4 hex castle nut envelope: hex 7/16 in across flats (basic) × 3/16 in (T basic), round collar Ø0.371 in (W min) up to 9/32 in overall height (H basic), six slots 0.10 in wide (S max) through the collar, bore Ø6.35 mm (1/4 in thread major diameter as a plain cylinder); no chamfers, fillet R or thread
- hex-castle-nut-1-2-envelope: [STEP](https://xemstudio.com/files/hardware/slotted-castle-nuts-inch-asme-b18-2-2/hex-castle-nut-1-2-envelope.step) · [STL](https://xemstudio.com/files/hardware/slotted-castle-nuts-inch-asme-b18-2-2/hex-castle-nut-1-2-envelope.stl) — 1/2 hex castle nut envelope: hex 3/4 in across flats (basic) × 13/32 in (T basic), round collar Ø0.637 in (W min) up to 9/16 in overall height (H basic), six slots 0.18 in wide (S max) through the collar, bore Ø12.70 mm (1/2 in thread major diameter as a plain cylinder); no chamfers, fillet R or thread
- hex-castle-nut-3-4-envelope: [STEP](https://xemstudio.com/files/hardware/slotted-castle-nuts-inch-asme-b18-2-2/hex-castle-nut-3-4-envelope.step) · [STL](https://xemstudio.com/files/hardware/slotted-castle-nuts-inch-asme-b18-2-2/hex-castle-nut-3-4-envelope.stl) — 3/4 hex castle nut envelope: hex 1-1/8 in across flats (basic) × 9/16 in (T basic), round collar Ø0.941 in (W min) up to 13/16 in overall height (H basic), six slots 0.24 in wide (S max) through the collar, bore Ø19.05 mm (3/4 in thread major diameter as a plain cylinder); no chamfers, fillet R or thread

## Questions

**What cotter pin for a 1/2 inch castle nut?**

McMaster-Carr lists a 7/64 in cotter pin hole for Grade 5 1/2-13 and 1/2-20 slotted nuts and 1/8 in for low-strength steel ones; the hex is 3/4 in across flats and 7/16 in high (slotted) per AFT's B18.2.2 table.

**How wide is the slot on a 3/8 inch slotted nut?**

0.15 in max and 0.12 in min (S), with an unslotted thickness T of 0.21 / 0.19 in on a 21/64 in thick nut.

**What is the difference between a slotted nut and a castle nut?**

A slotted nut has its slots cut in a plain hex; a castle nut has a round collar on top of the hex and the slots are cut through the collar (diameter W, 0.371 in min for 1/4).

## Fits with

- [Slotted and castle nuts, DIN 935-1, M4–M36: across flats, height, slot width, collar, cotter pin size + envelope models](https://xemstudio.com/objects/slotted-castle-nuts-din-935/)
- [Hex nuts, inch: #4-40 to 3/4-10 (ASME B18.2.2)](https://xemstudio.com/objects/hex-nuts-inch/)
- [Hex nuts, hex jam nuts and heavy hex nuts, inch 7/8 to 1-1/2 (ASME B18.2.2): across flats, thickness, UNC / UNF](https://xemstudio.com/objects/hex-nuts-inch-7-8-to-1-1-2-jam-heavy/)
- [Nylon-insert lock nuts, inch (ASME B18.16.6): 1/4 to 1-1/2 width across flats, across corners, height](https://xemstudio.com/objects/nylon-insert-lock-nuts-inch-asme-b18-16-6/)
- [Coupling nuts / long hex nuts: DIN 6334 M8–M36 (height 3 d) and inch rod coupling nuts 1/4 to 1 in — across flats, length + M8–M36 envelope models](https://xemstudio.com/objects/coupling-nuts-din-6334-and-inch/)
- [All-metal prevailing-torque lock nuts: DIN 980 V / M, ISO 7042 M5–M36 and inch Stover-type / top-lock nuts — across flats, height](https://xemstudio.com/objects/prevailing-torque-all-metal-nuts/)
- [R-clips, spring cotters and hairpin cotter pins: wire diameter, pin / shaft range, length (DIN 11024, McMaster hairpin sizes)](https://xemstudio.com/objects/r-clips-hairpin-cotters-din-11024/)
- [Clevis pins ISO 2341 B, Ø3 to Ø8](https://xemstudio.com/objects/clevis-pins/)