Hex bolt vs socket head cap screw: ISO 4014 / 4017 vs DIN 912 / ISO 4762
The choice between an external-wrench hex head and an internal-key socket head decides the tooling, the envelope and — at the top of the range — the strength class you can buy off the shelf. This page compares the four identifiers we publish specification pages for, two from each family, using only fields that mean the same thing across the columns. Where a figure is not established by the collected evidence, or sits at a different anchor size per column, the cell says so; nothing is converted or filled in with an assumption.
Comparison table
The hex columns come from the bolts family, the socket columns from the screws family — each cell links through to the full specification page.
| Field | ISO 4014 Hex Bolt (partial thread) in Bolts | ISO 4017 Hex Screw (full thread) in Bolts | DIN 912 Socket Head Cap Screw in Screws | ISO 4762 Socket Head Cap Screw in Screws |
|---|---|---|---|---|
| Standard & designation status | ISO 4014 — hexagon head bolt, product grades A/B, partially threaded; predecessor DIN 931 | ISO 4017 — hexagon head screw, product grades A/B, threaded to the head; predecessor DIN 933 | DIN 912 — hexagon socket head cap screw; current norm DIN EN ISO 4762 | ISO 4762 — the international designation that absorbed DIN 912 |
| Size range | M1.6–M64 (M1/M1.2/M1.4 rows in collected tables are manufacturer series — quote as specials) | M1.6–M64 (M1/M1.2/M1.4 rows in collected tables are manufacturer series — quote as specials) | M1.6–M64 | M1.6–M64 |
| Thread & extent The 4014/4017 split is thread extent, not strength; both share the same head geometry. | Metric coarse; partial thread with a standard-defined unthreaded shank | Metric coarse; full thread along the usable length beneath the head | Metric coarse, 6g (5g6g for class 12.9); threaded to the head | Metric coarse, 6g (5g6g for class 12.9); threaded to the head |
| Wrenching External hex wrench (across flats, s) versus internal hex key (socket, s) — different access and torque scale by design. Figures sit at each column's collected anchor size. | External wrench, s = 16 mm at M10 | External wrench, s = 16 mm at M10 (head geometry shared with ISO 4014) | Internal hex key, s = 8 mm nominal at M10 | Internal hex key, s = 10 mm nominal at M12 (different anchor size from the M10 columns — not directly comparable) |
| Head height (k) Each column quotes its own collected basis; the socket head is taller at the same diameter but bears on a smaller circular face. | k nominal 3.5 mm at M5, tabulated up to 40 mm at M64 | k nominal 3.5 mm at M5, tabulated up to 30 mm at M48 | k max 10.00 mm at M10 | k max 12.00 mm at M12 (different anchor size — not directly comparable) |
| Strength classes available | Property class per ISO 898-1, specified separately from the dimensional standard (8.8/10.9 typical) Conditional — confirm configuration | Property class per ISO 898-1, specified separately from the dimensional standard (8.8/10.9 typical) Conditional — confirm configuration | Steel 8.8, 10.9, 12.9; stainless A2, A4 — 12.9 the common stock condition | Steel 8.8, 10.9, 12.9; stainless A2, A4 — 12.9 the common stock condition |
| Where it wins Orientation drawn from the identifier pages and the linked knowledge guide, not a performance claim. | General and structural assemblies needing an external-wrench joint and a defined unthreaded shank | Through-bolting where full thread engagement or adjustment along the shank is needed | Precision equipment, tooling, tight envelopes — internal keying and a cylindrical head that fits counterbores | Same as DIN 912 under the international designation for global drawings |
- Verified
- Differs
- Unverified — confirm at RFQ
- Conditional — confirm configuration
How to choose
Within the hex family (4014 vs 4017)
The split is thread extent, not strength: ISO 4014 carries a defined unthreaded shank so shear lands on solid material, while ISO 4017 is threaded to the head for through-bolting where grip length varies. Both share head geometry, so the wrench investment does not change between them.
Within the socket family (DIN 912 vs ISO 4762)
These name the same screw — DIN 912's current norm is DIN EN ISO 4762 — so the choice follows the drawing and the receiving inspector's expectation, not the hardware. Quote the designation the drawing uses and certify against that wording.
Across the two families
Socket head cap screws stock in class 12.9 as the common condition, so coating choice follows the high-strength embrittlement guidance rather than the ordinary finishing shelf. Hex bolts cover the general and structural duty at 8.8 / 10.9 with full coating freedom including hot-dip galvanizing. The mechanism-level comparison is in the drive-comparison knowledge guide linked below.
Frequently asked questions
When does a socket head cap screw beat a hex bolt?
Three practical cases: a compact or counterbored envelope where a cylindrical head is the only head that fits; precision assemblies where an internal hex key avoids swinging a wrench; and high-strength compact joints, because socket caps ship in class 12.9 as the common stock condition. Where an external wrench, hot-dip galvanizing or structural practice governs, the hex bolt stays the right answer.
ISO 4014 or ISO 4017 — does the thread extent matter?
Yes, and it is a geometry decision, not a strength one. ISO 4014 carries a defined unthreaded shank, which puts shear on the solid shank rather than the threads — the usual choice for fitted structural joints. ISO 4017 is threaded to the head, which suits through-bolting where grip length varies or adjustment along the shank is needed. Both share the same head geometry, so the wrench does not change.
Are DIN 912 and ISO 4762 interchangeable on a drawing?
They name the same screw — DIN 912's current norm is DIN EN ISO 4762 — so the choice is usually about which designation the drawing and the receiving inspector expect. Quote the designation the drawing uses; if a customer standard still says DIN 912, ship and certify against that wording and confirm at RFQ.
Individual specification pages
Each identifier has its own page — full dimension tables, strength classes and RFQ guidance.
- ISO 4014 Hex Bolt (partial thread)
- ISO 4017 Hex Screw (full thread)
- DIN 912 Socket Head Cap Screw
- ISO 4762 Socket Head Cap Screw
The full drive-style mechanics and head-type selection: Hex bolt vs socket head cap screw compared
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What to include in your inquiry
- ✓ Standard and property class (e.g. DIN 912, ISO 4762, class 8.8) — or a drawing for custom parts.
- ✓ Sizes, lengths and thread type (metric or inch).
- ✓ Quantity per size and your target delivery date.
- ✓ Destination country, plus any coating or finish requirement.
- ✓ Any documents you need with the shipment (e.g. mill test certificate) so the quote includes them.
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