Hex bolts, inch: 1/4-20 to 3/4-10 (ASME B18.2.1) — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/hex-bolts-inch/  (CC BY 4.0)
Basis: ASME B18.2.1 hex bolt / cap screw: width across flats F, head height H (nominal)
Catalog version: 2026-10-20

Sizes: see table below
- Threads are plain cylinders at the major diameter, as every thread on this site.
- Length is under the head.

thread  tpi  af_in  head_h_in  lengths_in
1/4-20  20  0.4375  0.1562  0.5, 0.75, 1, 1.25, 1.5, 2, 2.5, 3
5/16-18  18  0.5  0.2031  0.75, 1, 1.25, 1.5, 2, 2.5, 3
3/8-16  16  0.5625  0.2344  0.75, 1, 1.25, 1.5, 2, 2.5, 3, 4
7/16-14  14  0.625  0.2812  1, 1.5, 2, 3
1/2-13  13  0.75  0.3438  1, 1.25, 1.5, 2, 2.5, 3, 4, 5, 6
5/8-11  11  0.9375  0.4219  1.5, 2, 3, 4, 5, 6
3/4-10  10  1.125  0.5  2, 3, 4, 5, 6

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- ASME: ASME B18.2.1 Square, hex, heavy hex and askew head bolts and hex, heavy hex, hex flange, lobed head and lag screws (inch) — standard — ASME; dimensions are facts [verify license at link] — https://www.asme.org/codes-standards/find-codes-standards/b18-2-1-square-hex-heavy-hex-askew-head-bolts-hex-heavy-hex-hex-flange-lobed-head-lag-screws-inch-series

Free files (CC BY 4.0, Xem Studio; STEP + STL, 47 parts): https://xemstudio.com/files/hardware/hex-bolts-inch/index.json
API: https://xemstudio.com/api/geometry?object=hex-bolts-inch