Split key rings 1/2 to 1-1/4 in: outside diameter, inside diameter and wire diameter (Key Ring maker table) — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/split-key-rings/  (sheet CC BY 4.0)
Basis: four keyring.com product pages (actual dimensions per nominal size); numbers only. mm values are the inch figures × 25.4
Catalog version: 2026-10-20

Sizes: see table below
- A split key ring is sold by a nominal diameter ('1 in'), which is approximate: keyring.com's actual figures are, for the stainless 1 in ring, outside diameter 1.100 in, inside diameter 0.932 in, wire diameter 0.072 in; for the 1/2 in stainless ring 0.670 / 0.510 / 0.050 in. Its pages also print dimensions called A and B for each ring (A .070 to .090 in, B .105 to .130 in); the pages do not define A and B, so the meanings are not given here.
- Different materials and origins of the same nominal size differ: the 3/4 in solid-brass ring is 0.875 in outside diameter and the 3/4 in stainless ring is listed at 0.880 in (its other dimensions are not printed). One page lists the 1-1/4 in ring as 'approximately 33 mm' outside diameter, against 1.255 in (31.9 mm) in its table; the table values are used. The 1 in nickel-plated and the 1-1/2 and 2 in rings are listed without dimensions in the pages read, and a retailer page for a 2 in Lucky Line ring gives only '2 in diameter' without saying outside or inside, so none of these is tabulated.
- S-hooks and other closed ring types were not tabulated: no maker table with wire diameter and opening was read. A split ring is two turns of wire; the turn spacing is not defined by the numbers published, so no ring is drawn.
- No file. McMaster-Carr lists split rings and tag rings with per-part CAD; linked, not copied. Ball chain, which also ends in a split ring or connector: ball-chain-sizes.

ring  nominal  outside diameter  inside diameter  wire diameter  A / B (as printed)
stainless steel, USA (type 304, spring tempered)  1/2 in  .670 in (17.02 mm)  .510 in (12.95 mm)  .050 in (1.27 mm)  .070 / .105 in
solid brass, USA  3/4 in  .875 in (22.22 mm)  .707 in (17.96 mm)  .072 in (1.83 mm)  .084 / .110 in
stainless steel, USA  1 in  1.100 in (27.94 mm)  .932 in (23.67 mm)  .072 in (1.83 mm)  .084 / .110 in
nickel plated, China  1-1/4 in  1.255 in (31.88 mm)  1.060 in (26.92 mm)  .090 in (2.29 mm)  .090 / .130 in

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- Key Ring (keyring.com): Split key rings: stainless 1/2 in USA, solid brass 3/4 in USA, stainless 1 in USA, nickel plated 1-1/4 in (China): outside / inside / wire diameter, A and B dimensions — web — Maker page; numbers only — https://www.keyring.com/stainless-steel-split-keyring-1_2-diameter-usa.aspx
- Key Ring (keyring.com): Solid brass split key ring 3/4 in (USA), actual dimensions — web — Maker page; numbers only — https://keyring.com/solid-brass-split-key-ring-3-4-inch-diameter-usa
- Key Ring (keyring.com): Stainless steel split key ring 1 in (USA) — web — Maker page; numbers only — https://keyring.com/stainlesssteelsplitkeyring1diameterusa.aspx
- Key Ring (keyring.com): Split key ring 1-1/4 in nickel plated (China) — web — Maker page; numbers only — https://keyring.com/split-key-ring-1-1-4-inch-diameter-nickel-plated-china
- McMaster-Carr: Split key rings and tag rings (free STEP/IGES per part, for your own design use; no redistribution) — STEP, IGES, PDF — McMaster-Carr site terms: personal design use, no redistribution [verify license at link] — https://www.mcmaster.com/chain/tag-rings-6

No true-size file yet: the published figures do not fix the whole shape; a measured scan is planned.
API: https://xemstudio.com/api/geometry?object=split-key-rings