DIN 933 vs ISO 4017 Difference

DIN 933 vs ISO 4017 difference explained for US RFQs—hex bolt wording, WAF gotchas, and order checklist.

DIN 933 vs ISO 4017 difference (short answer)

Both are fully threaded metric hex head screws/bolts. For most commercial buys they are treated as equivalents; the practical difference is standard system (DIN vs ISO) and width across flats (WAF) on a few sizes (especially M10, M12, M14, M22). Confirm tools before substituting.

What US buyers usually mean

In US RFQs you will often see hex bolt, hex head screw, or a drawing callout like DIN 933 / ISO 4017. For metric catalogs, both DIN 933 and ISO 4017 describe a fully threaded hex head fastener (often sold as a hex head screw / hex bolt).

Partial-thread cousins are different: DIN 931 ≈ ISO 4014 (shank + thread). Do not mix full-thread and partial-thread on the same critical fit without checking length under head and grip.

DIN 933 vs ISO 4017 at a glance

Item	DIN 933	ISO 4017
Product	Hex head, full thread	Hex head, full thread
Typical US wording	Hex bolt / hex head screw	Hex head screw (ISO callout)
Interchange	Common for commercial buying	Preferred on newer drawings
Watch-outs	Tool size on some diameters	Width across flats (WAF) differs for M10, M12, M14, M22

For most OEM/MRO buys, they are treated as the same product family—confirm WAF / wrench size when tooling is fixed, especially on M10–M14 and M22.

Can DIN 933 and ISO 4017 be interchanged?

Check before substitution	If it matches	If it does not match
Metric thread diameter and pitch	Continue the comparison	Keep the drawing standard and request review
Length measured under the head	Continue the comparison	Do not substitute
304 / A2-70 or other specified material and property class	Continue the comparison	Quote the specified grade; do not downgrade it
Fully threaded form	Continue the comparison	A shank normally points to DIN 931 / ISO 4014 instead
WAF / socket clearance on the affected sizes	Commercial substitution may be possible	Keep the specified head dimensions or obtain engineering approval

Buyer rule: treat DIN 933 and ISO 4017 as comparable full-thread families, not as an automatic line-by-line replacement. The drawing, mating parts, tooling, and approval requirements control the final choice.

How to order on Pisenfasten

Open hex head screws (our metric 304 / A2-70 line)
Match thread × length to the drawing
Pair with hex nuts and flat washers when the BOM requires a kit stack
Need 316 / A4 or a partial-thread DIN 931 style? Contact sales with the drawing
Buying cartons for resale or replenishment? Review the quote-specific Wholesale terms

Also see: A2-70 vs A4-80 and our parametric catalog.

To inspect real published choices, open M6 × 16 or M8 × 20. Those pages show current MOQ and tier pricing for the listed 304 / A2-70 items. For an exact standard, fixed wrench clearance, private-label packaging, or a non-catalog requirement, submit an RFQ with the drawing, quantity, and ship-to country; availability, documents, freight scope, and lead time are confirmed in writing.

RFQ checklist

Standard: DIN 933 or ISO 4017 (pick one primary)
Thread × length (under head)
Material / class: e.g. 304 A2-70 (or 316 / A4 if specified)
Full thread vs partial thread
Docs: MTC, RoHS, REACH
Qty + ship-to country

FAQ

Q: Can I substitute ISO 4017 for DIN 933?
A: Usually yes for commercial grades when diameter, length, pitch, and property class match. Recheck WAF on M10/M12/M14/M22 if sockets/tools are already purchased.

Q: Why do Americans say “hex bolt” but catalogs say “hex head screw”?
A: Trade language differs. In metric DIN/ISO catalogs, fully threaded hex heads are commonly listed as hex head screws; US buyers still search “hex bolt.”

Q: Do you stock 304 stainless hex heads?
A: Yes — browse hex head screws and filter by thread size.

Q: What about DIN 931 / ISO 4014?
A: Those are partial-thread hex bolts. Tell sales if the drawing shows an unthreaded shank.

DIN 933 vs ISO 4017 Difference (Hex Head Screws)