DIN ISO Fastener Standards: A Cross-Reference Guide
This is a comprehensive reference table covering the most important DIN and ISO standards for fasteners. It includes direct equivalents, notes on dimension differences where they exist, and practical information for engineers and procurement.
Hexagon Head Bolts & Screws
DIN
ISO / EN
Description
Notes / Key Changes
DIN 931
ISO 4014
Hexagon head bolts, partial thread
Width across flats differs for M10, M12, M14, M22
DIN 933
ISO 4017
Hexagon head bolts/screws, full thread
Width across flats differs for M10, M12, M14, M22
DIN 601
ISO 4016
Hexagon head bolts, product grade C, partial thread
Width across flats differs for M10, M12, M14, M22
DIN 558
ISO 4018
Hexagon head screws, product grade C, full thread
Width across flats differs for M10, M12, M14, M22
DIN 960
ISO 8765
Hexagon head bolts, fine pitch thread, partial thread
Width across flats differs for M10, M12, M14, M22
DIN 961
ISO 8676
Hexagon head bolts, fine pitch thread, full thread
Width across flats differs for M10, M12, M14, M22
DIN 6914
ISO 7412
Hexagon head bolts for structural HV bolting
–
DIN 6921
EN 1665
Hexagon flange bolts
Some head dimensions and widths across flats differ
DIN 603
ISO 8677
Mushroom head square neck (carriage) bolts
–
DIN 610
ISO 8676*
Hexagon fit bolts
Approximate equivalent
DIN 609
—
Hexagon head bolts with long thread
Limited direct ISO equivalent
Socket & Hexalobular (Torx) Screws
DIN
ISO
Description
Notes / Key Changes
DIN 912
ISO 4762
Hexagon socket head cap screws
Fine pitch thread covered in ISO 12474
DIN 6912
—
Low head socket cap screws with pilot recess
No direct ISO equivalent – still widely used
DIN 7984
—
Low head / thin head hexagon socket cap screws
No direct ISO equivalent – still widely used
DIN 7991
ISO 10642
Hexagon socket countersunk head screws
Some head heights and diameters changed; certain sizes omitted in ISO
Round washers for high-strength structural bolting
–
DIN 6340
—
Washers for clamping devices
–
DIN 6799
—
Retaining / lock washers for shafts
–
Important Notes
Standards marked with * are approximate or have no exact one-to-one equivalent.
Some standards have minor differences in head dimensions, widths across flats, or tolerances. Always verify exact specifications for critical applications or tight installation spaces.
Several older DIN standards have been withdrawn and replaced by ISO or EN ISO versions.
DIN 6912 and DIN 7984 remain valid standards with no current ISO replacement.
For blind rivets, the modern ISO 159xx series has largely replaced older DIN specifications.
This reference is intended as a practical guide. For production or safety-critical use, always consult the current official standard documents.
Engineering Disclaimer
This DIN to ISO conversion table is provided as a practical engineering reference only. While every effort has been made to ensure accuracy, fastener standards may differ in dimensions, tolerances, materials, mechanical properties and performance requirements. Users should always verify the latest applicable standards before specifying fasteners for safety-critical or structural applications.
Most Common DIN to ISO Equivalents
DIN
ISO
Product
DIN 931
ISO 4014
Hex Bolt
DIN 933
ISO 4017
Hex Screw
DIN 912
ISO 4762
Socket Head Cap Screw
DIN 7991
ISO 10642
CSK Socket Screw
DIN 934
ISO 4032
Hex Nut
DIN 125
ISO 7089
Plain Washer
DIN 433
ISO 7092
Small Series Washer
DIN 7985
ISO 7045
Pan Head Machine Screw
DIN 965
ISO 7046
CSK Machine Screw
DIN 966
ISO 7047
Raised CSK Machine Screw
DIN 982
ISO 7040
Nylon Insert Lock Nut
DIN 985
ISO 10511
Thin Nylon Lock Nut
DIN 1481
ISO 8752
Spring Pin
Frequently Asked Questions
What is the difference between DIN, ISO and EN fastener standards?
DIN standards are German standards developed by the Deutsches Institut für Normung (DIN), ISO standards are international standards developed by the International Organization for Standardization (ISO), and EN standards are European standards adopted across member countries. Many traditional DIN fastener standards have been replaced by equivalent ISO or EN standards.
Are DIN and ISO fasteners always interchangeable?
No. While many DIN standards have direct ISO replacements, some standards have dimensional changes such as head height, width across flats, thread pitch, or mechanical properties. Always verify interchangeability before using fasteners in critical applications.
Why were many DIN fastener standards replaced by ISO standards?
The transition from DIN to ISO standards was undertaken to harmonize engineering standards internationally, improve interchangeability, and facilitate global manufacturing and trade.
What does “DIN standard withdrawn” mean?
A withdrawn DIN standard indicates that the original German standard is no longer maintained and has either been replaced by an ISO or EN standard or discontinued without a direct replacement.
What does “DIN still valid” mean?
Some DIN standards remain active and continue to be widely used because no equivalent ISO standard exists. Examples include DIN 315 wing nuts, DIN 580 lifting eye bolts, and DIN 7984 low-head socket screws.
Does every DIN fastener standard have an ISO equivalent?
No. Many DIN standards have no direct ISO replacement and continue to remain valid independently.
What is the difference between direct replacement and limited interchangeability?
A direct replacement means the ISO standard can generally replace the DIN standard without design changes. Limited interchangeability means there may be differences in dimensions, tolerances, or performance characteristics that require verification.
Which DIN fastener standards are most commonly searched?
The most commonly referenced standards include: DIN 933 → ISO 4017 DIN 931 → ISO 4014 DIN 912 → ISO 4762 DIN 934 → ISO 4032 DIN 125 → ISO 7089 DIN 7985 → ISO 7045 DIN 965 → ISO 7046 DIN 985 → ISO 10511 DIN 6923 → EN 1661 DIN 7991 → ISO 10642
