Cross-references the most-used industrial fastener standards from DIN (Germany, legacy), ISO (international), and ASME B18 (United States). Covers hex head cap screws (DIN 931 / 933 vs ISO 4014 / 4017 vs ASME B18.2.1), socket head cap screws (DIN 912 vs ISO 4762 vs ASME B18.3), nuts (DIN 934 vs ISO 4032 vs ASME B18.2.2), washers (DIN 125 vs ISO 7089 vs ASME B18.22), thread pitch (metric coarse vs fine, UN / UNC / UNF), property class (8.8, 10.9, 12.9 vs A2-70, A4-80, ASTM A490), and torque calculation from bolt class.
Direct DIN / ISO / ASME cross-reference
DIN standards are the legacy German standards; most were superseded by ISO equivalents in the 1990s and 2000s, but the DIN numbers remain in common use across Europe. ASME B18 covers the parallel US standards. The table below pairs the identical-geometry standards; where the two differ (headstyle, wrench size, thread pitch) the difference is noted.
Product
DIN
ISO
ASME B18
Notes
Hex head cap screw (full thread)
DIN 933
ISO 4017
B18.2.1 (fully threaded)
DIN 933 = ISO 4017 for M5 to M39
Hex head cap screw (partial thread)
DIN 931
ISO 4014
B18.2.1 (partly threaded)
Same geometry; wrench across-flats differs on M10 and M12
Socket head cap screw
DIN 912
ISO 4762
B18.3
DIN 912 has larger head Ø on some sizes
Countersunk socket screw
DIN 7991
ISO 10642
B18.3
Nearly identical geometry
Button head socket screw
DIN EN ISO 7380
ISO 7380
B18.3
ISO covers both types
Hex nut standard
DIN 934
ISO 4032
B18.2.2
DIN 934 slightly taller head
Hex nylon-insert lock nut
DIN 985
ISO 10511
B18.16.6
Nyloc / Stop-nut
Prevailing-torque all-metal lock nut
DIN 980
ISO 7042
B18.16.6
High-temperature lock nut
Plain washer
DIN 125
ISO 7089
B18.22
Same OD and thickness M5-M36
Spring washer
DIN 127
—
B18.21
ISO deprecated in favour of self-locking nuts
Tooth lock washer
DIN 6798
ISO 10673
B18.22
Ext / int / countersunk variants
Threaded insert (self-tapping)
DIN 8140
ISO 1234
—
Helicoil, Recoil, Time-Sert branded
Property class — carbon steel bolts
Class
Nominal tensile (MPa)
Yield (MPa)
Typical use
4.6
400
240
Low-duty assembly, non-structural
5.8
500
400
General mechanical
8.8
800
640
Standard for machinery, drive assemblies
10.9
1000
900
High-stress structural, engine, gearbox
12.9
1200
1080
Precision engine internals, hydraulic manifolds
Property class — stainless steel bolts (A2 / A4)
Grade
Alloy
Cold-work class
Tensile (MPa)
A2-70
AISI 304 / 1.4301
Cold-worked
700
A2-80
AISI 304 / 1.4301
Heavy cold-worked
800
A4-70
AISI 316 / 1.4401
Cold-worked
700
A4-80
AISI 316 / 1.4401
Heavy cold-worked
800
A4L-80
AISI 316L / 1.4404
Heavy cold-worked, low C
800
Thread pitch — metric coarse vs. fine (M6 to M24)
Nominal
Coarse pitch
Fine pitch
Pitch dia (M-coarse)
M6
1.0 mm
0.75 mm
5.350 mm
M8
1.25 mm
1.0 mm
7.188 mm
M10
1.5 mm
1.25 mm
9.026 mm
M12
1.75 mm
1.25 mm
10.863 mm
M14
2.0 mm
1.5 mm
12.701 mm
M16
2.0 mm
1.5 mm
14.701 mm
M18
2.5 mm
1.5 mm
16.376 mm
M20
2.5 mm
1.5 mm
18.376 mm
M22
2.5 mm
1.5 mm
20.376 mm
M24
3.0 mm
2.0 mm
22.051 mm
Torque calculation from property class
Recommended tightening torque T = K × d × F, where K is the friction coefficient (0.20 for dry uncoated, 0.14 for zinc-plated with light oil, 0.10 for MoS₂ paste), d is nominal diameter, and F is the target preload (typically 70% of proof load). A M10 × 8.8 dry bolt tightened to nominal K = 0.20 targets ~50 Nm; the same bolt with MoS₂ paste at K = 0.10 targets ~25 Nm — halving the torque figure. Always calibrate the K value against the assembly's actual lubrication state.
Dimensionally interchangeable for practical purposes — both are fully-threaded hex head cap screws; width-across-flats differs at a few sizes (e.g. M10/M12/M14) between old DIN and ISO.
What is the ISO equivalent of DIN 912?
ISO 4762 — the socket head cap screw; ASME's counterpart is B18.3.
Why do DIN and ISO numbers both still appear?
European catalogues migrated to ISO but drawings and stores systems still carry DIN numbers; the comparison table exists precisely because both will be quoted for decades.