DIN Standards Explained: DIN 934, 985, 71802 Fasteners Guide UK
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DIN Standards Explained: What DIN 934, DIN 985, DIN 71802 Actually Mean
If you've ever shopped for engineering hardware, you've seen DIN numbers everywhere — DIN 934, DIN 985, DIN 71802, DIN 71803. But what do they actually mean? And why do they matter when you're just trying to buy a nut or a ball joint?
This guide explains DIN standards in plain English, why they exist, and which numbers you'll see on the most common UK engineering hardware.
What Is a DIN Standard?
DIN stands for Deutsches Institut für Normung — the German Institute for Standardisation. Since 1917, it has published thousands of technical specifications that define exactly how a part should be manufactured: dimensions, materials, tolerances, and thread specifications.
DIN standards are now used worldwide. When you buy a "DIN 934 M8 nut" from any supplier, you know it will:
- Have the exact same dimensions
- Fit the same wrench size
- Screw onto the same M8 bolt
- Meet the same strength specifications
This is why DIN numbers matter — they guarantee compatibility between parts from different manufacturers, decades apart.
The Most Common DIN Standards You'll Encounter
DIN 934 — Hex Nuts (Standard Full Nuts)
The most common nut standard in the world. If you buy a standard hexagonal nut in any thread size (M3 to M100), it's almost certainly DIN 934 compliant.
- Standard hexagonal shape
- Full-thickness ("full nut")
- Metric coarse thread
- Available in mild steel, stainless steel, brass
- Wrench sizes standardised by thread size
Where you'll see it: General fasteners, machinery, furniture, automotive.
DIN 985 — Nyloc Lock Nuts (Prevailing Torque Nuts)
Also called "nylon insert lock nuts." These have a coloured nylon ring inside the top of the nut. When you tighten them, the nylon deforms around the bolt threads, providing a strong locking force that resists vibration.
- Hexagonal shape (like DIN 934)
- Nylon ring at the top
- Self-locking — no washer needed
- Cannot be reused (nylon deforms permanently)
Where you'll see it: Anywhere with vibration — motorsport, machinery, engine mounts, agricultural equipment.
DIN 71802 — Ball Joint Sockets (Gas Strut Fittings)
The standard for ball joint end fittings used on gas struts and gas springs. Defines the socket size, thread type, and snap-on design.
- Socket ball size: 10mm, 13mm, or 16mm
- Female metric thread (M6, M8, M10)
- Snap-on design for tool-free installation
- Compatible with matching DIN 71803 ball studs
Where you'll see it: Gas strut end fittings, gas spring assemblies, hood support systems.
DIN 71803 — Ball Studs (Gas Strut Studs)
The matching standard for the male "stud" side of a gas strut ball joint. These have a ball at the end that snaps into a DIN 71802 socket.
- Ball sizes: 10mm, 13mm, 16mm (matching DIN 71802)
- Male metric thread (M6, M8, M10)
- Threaded to screw into a bracket or plate
- Precision-turned ball for smooth articulation
Where you'll see it: Bolt-on mounting points for gas struts, brackets, custom rig fabrication.
DIN 71752 — Clevis Fork Ends (Rod End Yokes)
The standard for U-shaped fork end fittings that connect gas struts, actuators, or hydraulic cylinders to a linkage point.
- U-shape "fork" with central hole for a pin
- Male metric thread (M6, M8, M10)
- Spring clip retention
- Zinc plated finish standard
Where you'll see it: Hydraulic and pneumatic actuators, custom gas strut installations, industrial linkages.
DIN 933 — Hex Bolts (Full-Thread Bolts)
Similar to DIN 934 nuts but for the corresponding bolts. Fully threaded from head to tip.
Where you'll see it: General fasteners, machinery assembly, structural applications.
DIN 125 — Flat Washers
Standard flat washers used with hex nuts and bolts to distribute load and protect surfaces.
Where you'll see it: Universal — used alongside almost every bolt-and-nut combination.
Understanding Material Grades: A2, A4, 8.8, 10.9
DIN numbers describe the shape and dimensions. Material grades describe the strength and corrosion resistance.
Stainless Steel Grades
- A2 (304 stainless) — Standard stainless. Excellent corrosion resistance, non-magnetic. Perfect for most outdoor and marine use.
- A4 (316 stainless) — Marine stainless. Higher corrosion resistance, including salt spray. Recommended for direct seawater contact.
Steel Strength Grades
- 4.6 — Basic mild steel. Suitable for light-duty domestic use.
- 8.8 — Medium-strength steel. Standard for most engineering fasteners.
- 10.9 — High-strength steel. Automotive, machinery, structural.
- 12.9 — Very high-strength. Motorsport, specialised industrial.
Corrosion Finishes
- Zinc plated (blue passivated) — Standard finish. Good corrosion resistance for indoor/sheltered outdoor use.
- Galvanised (hot-dip) — Thick coating for outdoor structural use.
- Black oxide — Aesthetic finish. Limited corrosion protection.
How to Read a Product Description
A typical engineering fastener listing might read:
M8 Hex Nut A2 304 DIN 934 – 10 Pack
Here's what each part means:
- M8 — Metric thread size 8mm
- Hex Nut — Standard hexagonal shape
- A2 304 — Made from 304 stainless steel (A2 grade)
- DIN 934 — Meets DIN 934 standard for dimensions
- 10 Pack — Quantity in the package
This tells you everything you need to know about compatibility, strength and corrosion resistance in one line.
Why DIN Compatibility Matters
If you replace a nut on a machine and the new nut is dimensionally different, the whole assembly may not fit properly. Bolts may not thread correctly, wrenches may not fit, and torque values may be wrong.
Buying to DIN standards means:
- Your new part will fit the existing bolt
- The wrench size will be standard
- The strength rating will be known
- Multiple suppliers will provide identical parts
FAQs About DIN Standards
Is DIN the same as ISO? Very similar, but not identical. ISO (International Organisation for Standardisation) is the international equivalent. Many DIN standards have been replaced or updated by ISO standards, but the old DIN numbers remain in common use in the UK and Europe.
Are DIN 934 nuts stronger than DIN 985 nyloc nuts? The nut itself is similar. DIN 985 nyloc nuts stay tight under vibration thanks to the nylon insert, but the mechanical strength is comparable.
Can I use a DIN 934 nut with an American UNC bolt? No — DIN standards are metric. American UNC and UNF bolts use imperial threads, which are incompatible.
Do I need DIN-standard parts, or can I use generic ones? For structural or safety-critical applications (motorsport, machinery, load-bearing), always use DIN-compliant parts with a known material grade. For light-duty domestic use, generic parts may be fine.
How can I tell if a nut is really DIN 934? Quality suppliers will state the DIN number and material grade. Reputable manufacturers stamp their nuts with markings. If in doubt, ask the supplier for a Declaration of Conformity.
Shop DIN-Standard Fasteners at SpringFix UK
We stock genuine DIN-compliant engineering hardware:
- Stainless Steel Fasteners → (DIN 934 hex nuts, DIN 985 nyloc lock nuts, A2 304 grade)
- Gas Strut End Fittings → (DIN 71802 ball sockets, DIN 71803 ball studs, DIN 71752 clevis forks)
All parts dispatched same-day from UK stock. Full DIN specifications on every product page.
Article by SpringFix UK — Engineering fasteners, gas struts and precision hardware. UK based, UK dispatched.