Deterministic evaluation of fastener standards based on geometry, material, and compliance constraints. Complete engineering specifications across all 66 size/grade/finish variants.
Hex cap screws, imperial series. Nominal dimensions for width across flats (s) and head height (k) across 11 metric sizes. Values in millimetres.
| Size | Width Across Flats (s) | Head Height (k) |
|---|---|---|
| 1/4 | 11.13 | 4.78 |
| 5/16 | 12.7 | 5.59 |
| 3/8 | 14.27 | 6.81 |
| 7/16 | 15.88 | 8 |
| 1/2 | 19.05 | 9.25 |
| 9/16 | 20.62 | 10.01 |
| 5/8 | 23.83 | 11.56 |
| 3/4 | 28.57 | 13.79 |
| 7/8 | 33.32 | 16.1 |
| 1-1/8 | 42.88 | 20.19 |
| 1-1/4 | 47.62 | 22.5 |
ASME B18.2.1 is dimensionally cross-referenced with the following standards:
| Standard | Name | Status | Risk Note |
|---|---|---|---|
| ASME B18.2.1, DIN 933, DIN 931, ISO 4017, ISO 4014, ISO 4032, ISO 7089, DIN 934, DIN 125-A, ASME B18.2.2, DIN 912, ISO 4762 | Equivalent standards in cluster | IN CLUSTER | — |
| Related Standard | Relationship | Confidence |
|---|---|---|
| DIN 933 | Cross-system | 0.72 |
| ISO 4017 | Cross-system | 0.70 |
ASME B18.2.1 in the concept layer — Fastener Knowledge:
Select a size to view its complete engineering data — including dimensional tolerances, material grades, mechanical properties, and surface finish options.
Non-canonical standard paths are automatically redirected to their canonical ISO equivalents via the Engineering Data Authority Lock. Equivalent standards: ASME B18.2.1, DIN 933, DIN 931, ISO 4017, ISO 4014, ISO 4032, ISO 7089, DIN 934, DIN 125-A, ASME B18.2.2, DIN 912, ISO 4762
| Source (Non-Canonical) | Target (Canonical Route) |
|---|---|
| No redirects — this is the canonical standard | |
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FROZEN: 2026-08-17 20:13:55
ASSET: standard_map_core.csv
CLUSTER: [ASME B18.2.1, DIN 933, DIN 931, ISO 4017, ISO 4014, ISO 4032, ISO 7089, DIN 934, DIN 125-A, ASME B18.2.2, DIN 912, ISO 4762]
A heavy hex bolt is a head-style variant of the hex bolt: a wider across-flats and a deeper head than the standard hex, for more bearing area in structural connections. It is not a different thread or a different material — the shank, the thread and the grade still follow the standard and the grade you name on the enquiry.
We do not publish heavy-hex dimensions on this page; the table on your drawing or specification governs. Send the drawing or ask for the size chart and we quote to the standard and edition you are working to. Ask for a heavy-hex quote.
A heavy hex bolt has a larger across-flats and a deeper head than a standard hex bolt, which gives more bearing area in a structural connection. The shank, thread and grade still follow the standard and grade named on the drawing or specification; the head style does not change them on its own.
Structural fasteners are normally specified to ASME B18.2.6 (Fasteners for Use in Structural Applications), while general hex bolts and screws are covered by ASME B18.2.1. Where a project specification or drawing names a different edition or an ASTM property grade, that document governs — tell us which one you are working to and we quote to it.
ASME B18.2.1 Hexagon Head Bolt per ASME B18.2.1 specification, available in Grade 5 grade with Plain finish. Engineered for industrial OEM applications requiring 827.0 MPa tensile strength and reliable long-term fastening performance.