Dimensions & technical reference
DIN 931-1:1987
Partially threaded geometry. Thread length b depends on total length L. DIN and ISO head dimensions differ at some diameters; select one standard.
| Nominal size | P | k nominal | s max | b · L ≤ 125 | b · 125 < L ≤ 200 | b · L > 200 |
|---|---|---|---|---|---|---|
| M1.6 | 0.35 | 1.1 | 3.2 | 9 | - | - |
| M2 | 0.4 | 1.4 | 4 | 10 | - | - |
| M2.5 | 0.45 | 1.7 | 5 | 11 | - | - |
| M3 | 0.5 | 2 | 5.5 | 12 | - | - |
| (M3.5) | 0.6 | 2.4 | 6 | 13 | - | - |
| M4 | 0.7 | 2.8 | 7 | 14 | - | - |
| M5 | 0.8 | 3.5 | 8 | 16 | 22 | - |
| M6 | 1 | 4 | 10 | 18 | 24 | - |
| (M7) | 1 | 4.8 | 11 | 20 | 26 | - |
| M8 | 1.25 | 5.3 | 13 | 22 | 28 | - |
| M10 | 1.5 | 6.4 | 17 | 26 | 32 | 45 |
| M12 | 1.75 | 7.5 | 19 | 30 | 36 | 49 |
| (M14) | 2 | 8.8 | 22 | 34 | 40 | 53 |
| M16 | 2 | 10 | 24 | 38 | 44 | 57 |
| (M18) | 2.5 | 11.5 | 27 | 42 | 48 | 61 |
| M20 | 2.5 | 12.5 | 30 | 46 | 52 | 65 |
| (M22) | 2.5 | 14 | 32 | 50 | 56 | 69 |
| M24 | 3 | 15 | 36 | 54 | 60 | 73 |
| (M27) | 3 | 17 | 41 | 60 | 66 | 79 |
| M30 | 3.5 | 18.7 | 46 | 66 | 72 | 85 |
| (M33) | 3.5 | 21 | 50 | 72 | 78 | 91 |
| M36 | 4 | 22.5 | 55 | 78 | 84 | 97 |
| (M39) | 4 | 25 | 60 | 84 | 90 | 103 |
Dimensional source: 164580 · DIN 931-1:1987 ↗. “—” means no value listed for this combination. P is thread pitch; min / max are dimensional limits. The selection above is not the full standard or a stock list.
ISO alternative: verify before substitution
| Nominal size | P | k nominal | s max |
|---|---|---|---|
| M1.6 | 0.35 | 1.1 | 3.2 |
| M2 | 0.4 | 1.4 | 4 |
| M2.5 | 0.45 | 1.7 | 5 |
| M3 | 0.5 | 2 | 5.5 |
| (M3.5) | 0.6 | 2.4 | 6 |
| M4 | 0.7 | 2.8 | 7 |
| M5 | 0.8 | 3.5 | 8 |
| M6 | 1 | 4 | 10 |
| (M7) | 1 | 4.8 | 11 |
| M8 | 1.25 | 5.3 | 13 |
| M10 | 1.5 | 6.4 | 16 |
| M12 | 1.75 | 7.5 | 18 |
| (M14) | 2 | 8.8 | 21 |
| M16 | 2 | 10 | 24 |
| (M18) | 2.5 | 11.5 | 27 |
| M20 | 2.5 | 12.5 | 30 |
| (M22) | 2.5 | 14 | 34 |
| M24 | 3 | 15 | 36 |
| (M27) | 3 | 17 | 41 |
| M30 | 3.5 | 18.7 | 46 |
| (M33) | 3.5 | 21 | 50 |
| M36 | 4 | 22.5 | 55 |
Dimensional source: 164580 · ISO 4014:2022 ↗. “—” means no value listed for this combination. P is thread pitch; min / max are dimensional limits. The selection above is not the full standard or a stock list.
Catalog inquiry range: M5 - M64. Availability, lengths, grades and finishes are confirmed by quotation. Sizes outside the cited reference table require the applicable standard dimensions or an approved drawing. Quote the exact standard and edition; DIN, ISO and U.S. references are not automatically interchangeable.
Reading the drawing and dimensions
All dimensions are in millimetres. d identifies the nominal thread diameter; P is pitch; L is measured from below the head; k is head height; s is width across flats. b identifies threaded length and depends on L. Sizes in parentheses are non-preferred in the cited DIN reference. Product grades A and B describe dimensional tolerances, not the mechanical property class.
The DIN reference above covers M1.6–M39; larger DIN 931 dimensions require the appropriate part of the standard or an agreed drawing. This reference scope is separate from the catalog inquiry range and does not indicate stock.
Applications and selection
General machinery and fabricated assemblies that call for a defined unthreaded grip length.
Specify nominal length and required threaded length together. The smooth shank must be compatible with the grip, clearance hole and thread engagement.
DIN 931 and ISO 4014: what to check
DIN 931 is a legacy designation; ISO 4014 is its successor reference. Specify the required standard and edition when ordering. Similar product names do not establish that every dimension is interchangeable.
| Nominal size | DIN 931 / DIN 933 | ISO 4014 / ISO 4017 |
|---|---|---|
| M10 | 17 | 16 |
| M12 | 19 | 18 |
| M14 | 22 | 21 |
| M22 | 32 | 34 |
These differences affect wrench selection and head clearance. Check the complete specification before accepting a substitution. The reference tables below retain their named editions.
Technical cross-check: Würth DIN / ISO hex-head comparison ↗.
Materials, surface finishes and standards
Materials for this series: Carbon Steel, Stainless Steel, Alloy Steel. Surface finishes: Black Oxide, Zinc Plated, HDG. Compatibility between the grade, finish and operating environment needs to be confirmed.
For titanium, nickel alloy or other non-ferrous requirements, include the exact material grade and drawing. Required mechanical properties, inspection documents and traceability should be stated in the inquiry.
Related U.S. references for hex bolts and hex cap screws. Confirm thread series, body length, head geometry and grade. Standards from different systems can vary in dimensions, threads, product scope and test requirements. Confirm the exact designation and edition in the quotation.
Technical reference: ISO 4014 hexagon head bolt scope. Product dimensions and the quoted standard must be confirmed together.
Ordering standard
DIN 931-1:1987; ISO 4014:2022
United States references for a separate inquiry: ASME B18.2.1 (inch); ASME B18.2.3.1M (metric). Confirm the exact form, thread system and drawing before quoting.
Material and property-class reference — 1987 edition
The cited DIN reference lists steel classes 5.6, 8.8 and 10.9. Its stainless reference includes A2-70 / A4-70 through M20 and A2-50 / A4-50 above M20. These are historical standard references, not a list of SPM stock. State the required material, class and mechanical standard on your order; supply is confirmed per order.
The reference thread tolerance is 6g. Coating and mating-thread requirements must be agreed together. Do not assume the same tolerance arrangement applies to every coating.
Reference: 易紧通 / 164580 — DIN 931-1:1987 ↗. Verify contractual requirements against the applicable official standard.
Reference weight & freight planning
Unit weight depends on diameter, length, thread length, material and the agreed geometry. Ask for the weight for your exact specification; DIN 933 full-thread weights should not be used as a DIN 931 weight table.
Freight planning: ask for net weight, packed gross weight, carton count and pallet dimensions for the quoted quantity. Part weight alone does not determine shipment weight. View carton and pallet information ↑
Request a DIN 931 bolt quotation
Start with the size and quantity you need. Add your material grade, strength class, finish and destination if known; we can confirm remaining details by email.
| Item | What to specify |
|---|---|
| Standard | DIN 931 and edition, or ISO 4014 if that is the required specification |
| Size and thread | Nominal diameter d, pitch P and under-head length L; required thread length b and grip requirements |
| Material and mechanical properties | Exact material grade and required property class; do not specify only “steel” or “stainless” |
| Surface finish | Required coating or finish, including any drawing or project requirements |
| Quantity and packing | Quantity for each size; box, label and packing requirements |
| Inspection and delivery | Required inspection documents, destination country/port and requested delivery date |
RFQ format: DIN 931 [edition] / M[diameter] × [pitch] × [length] / thread length [b] / [material and class] / [finish] / [quantity] / [destination].
MOQ, sample arrangements, lead time, inspection documents and final packing details are confirmed per order. Tell us your requested delivery date; it is reviewed during quotation rather than treated as a guaranteed dispatch date.
Request DIN 931 pricing →DIN 931 procurement questions
What is the difference between DIN 931 and DIN 933?
DIN 931 describes a partially threaded configuration with a smooth shank. DIN 933 describes a fully threaded configuration, allowing for the specified under-head runout. Select the configuration required by the assembly drawing.
Can ISO 4014 replace DIN 931?
Confirm the standard edition, head dimensions, thread, material and mechanical requirements before substitution. The comparison above highlights selected head-width differences; it is not a complete interchangeability assessment.
Which strength class and finish should I request?
Provide the class and finish required by your drawing or project specification. A dimensional standard alone does not identify the required material strength or coating. We review the requested combination with the quotation.
Are the displayed dimensions a stock list?
No. The tables are technical reference dimensions. The catalog inquiry range is not a promise that every length, grade or finish is available.
Can I order matching nuts and washers?
Include the nut and washer requirements in the same inquiry. State their standards, thread, material or property class and finish so the complete assembly can be reviewed.