Nyloc Nut Sizes: Complete Guide for Industrial Buyers

Selecting the correct Nyloc Nut Sizes requires more than choosing an M6, M8, M10 or M12 thread.

A Nyloc-type nut is a prevailing-torque fastener. Its non-metallic insert interacts with the mating bolt thread and creates rotational resistance.

Industrial buyers should therefore select it using:

Thread → Pitch → Nut Type → Standard → Dimensions → Mechanical Requirement → Material → Insert → Coating → Mating Bolt → Temperature → Prevailing Torque

This is especially important for automotive, machinery, automation and industrial equipment where consistent assembly and locking performance matter.

What Are Nyloc Nut Sizes?

Nyloc Nut Sizes are defined by the internal thread plus the dimensions and product form of the prevailing-torque nut. Important factors include thread diameter, pitch, width across flats, nut-body height, overall height including the locking feature, material, mechanical properties and applicable standard.

An M8 Nyloc nut is therefore not completely specified by the word:

What Does M8 Nyloc Nut Mean?

An M8 Nyloc nut has a nominal metric internal thread diameter of:

8 mm

For a common coarse thread:

M8 × 1.25

But that still does not define:

Regular, high or thin nut
Overall height
Width across flats
Mechanical requirement
Material
Coating
Insert
Functional prevailing torque

The applicable standard or customer drawing is still required.

Common Metric Nyloc Nut Thread Sizes

Depending on the applicable standard, metric non-metallic-insert prevailing-torque nuts cover a broad range.

Common OEM requirements include:

Thread	Common Coarse Pitch
M3	0.5 mm
M4	0.7 mm
M5	0.8 mm
M6	1.0 mm
M8	1.25 mm
M10	1.5 mm
M12	1.75 mm
M14	2.0 mm
M16	2.0 mm
M20	2.5 mm
M24	3.0 mm

Larger sizes can also fall within applicable ISO product ranges.

The actual product standard should control.

M3 Nyloc Nut

M3 is used in suitable smaller assemblies such as:

Electronics equipment
Light automation
Instruments
Small brackets
Equipment covers

The designer should still check:

Nut type
Available space
Mating screw
Mechanical requirement
Insert performance

Small size does not remove the need for correct joint design.

M4 Nyloc Nut

M4 can suit suitable:

Electrical equipment
Automation components
Light machinery
Instrumentation
Enclosures

For automated assembly, thread start and prevailing-torque consistency can be particularly important.

M5 Nyloc Nut

M5 is common in suitable:

Equipment
Machinery guards
Automotive components
Automation
Electrical assemblies

ISO 2320’s functional scope for coarse-thread prevailing-torque steel nuts starts at M5.

This does not mean smaller ISO product-standard nuts do not exist. For example, ISO 7040:2025 covers regular products down to M3.

M6 Nyloc Nut

M6 is widely encountered in:

Machinery
Automation equipment
Brackets
Equipment frames
Automotive assemblies

Selection should still include:

M6 × Pitch + Nut Type + Standard + Mechanical Requirement + Finish

Do not purchase only by diameter.

M8 Nyloc Nut

M8 is frequently used in industrial equipment and machinery.

Important checks include:

M8 × 1.25 coarse or specified fine pitch
Regular/high/thin type
Mechanical compatibility with bolt
Coating
Temperature
Prevailing torque

M10 Nyloc Nut

M10 can be used in suitable:

Machinery
Industrial equipment
Automotive assemblies
Material-handling equipment

Do not assume a larger nut automatically provides better vibration performance.

The complete joint determines performance.

M12 Nyloc Nut

M12 requirements may vary significantly depending on:

Thread pitch
Nut type
Bolt properties
Service load
Temperature
Coating

A complete RFQ should identify all of these.

M14 and M16 Nyloc Nuts

Larger locking nuts can be used in suitable equipment and machinery.

As size and joint load increase, mechanical compatibility with the mating bolt becomes increasingly important.

Do not specify a generic:

M16 Nyloc Nut

for an engineered joint without additional requirements.

Nyloc Nut Size Does Not Define Strength

This distinction is critical.

For example:

M10

defines the nominal thread diameter.

It does not independently define:

Nut property requirement
Nut material
Heat treatment
Proof capability
Coating
Prevailing torque

Size and mechanical properties are separate specification elements.

Main Nyloc Nut Dimensions

Important Nyloc Nut Dimensions can include:

d — Thread Diameter

The nominal internal thread diameter.

P — Thread Pitch

The distance between adjacent metric thread forms.

s — Width Across Flats

The hexagonal wrenching dimension.

m — Nut-Body Height

The relevant metal nut-body dimension under the applicable product design.

h — Overall Height

The total product height including the prevailing-torque feature.

Exact symbols and definitions should follow the applicable standard or drawing.

Why Overall Height Matters

A Nyloc nut contains an additional prevailing-torque feature above the basic nut body.

Therefore, overall height matters for:

Assembly clearance
Bolt length
Tool access
Nearby components
Packaging of the joint

This is particularly important in compact machinery and automation systems.

Width Across Flats

Width across flats affects:

Socket selection
Wrench access
Automated tool access
Assembly envelope

Do not assume all lock nuts with the same thread have the same external dimensions.

The applicable product standard controls.

Regular vs High vs Thin Nyloc Nut Dimensions

Current ISO standards distinguish three important coarse-thread product forms:

Product Form	Current ISO	Coarse Thread Range
Regular	ISO 7040:2025	M3–M39
High	ISO 7041:2025	M5–M39
Thin	ISO 10511:2025	M3–M39

All three cover steel and stainless-steel products with product grades A and B within their respective scopes.

ISO 7040:2025 Regular Nyloc Nut

ISO 7040:2025 specifies regular prevailing-torque hexagon nuts with non-metallic inserts.

Its scope covers:

Steel
Stainless steel
Metric coarse pitch
M3 to M39
Product grades A and B

ISO states that the regular nut’s overall height is based on the relevant style-1 minimum nut height plus the prevailing-torque feature.

ISO 7041:2025 High Nyloc Nut

ISO 7041:2025 covers high prevailing-torque hexagon nuts with non-metallic inserts.

Its scope includes:

Steel
Stainless steel
Metric coarse pitch
M5 to M39
Product grades A and B

The high design uses the relevant style-2 nut-height basis plus the prevailing-torque feature.

ISO 10511:2025 Thin Nyloc Nut

ISO 10511:2025 covers thin prevailing-torque hexagon nuts with non-metallic inserts.

Its scope includes:

Steel
Stainless steel
Metric coarse pitch
M3 to M39
Product grades A and B

Its geometry uses the relevant style-0 nut-height basis plus the prevailing-torque feature.

Interesting ISO Design Detail

The current ISO product standards state that, for a given nominal diameter, the height of the non-metallic prevailing-torque feature is identical across the regular, high and thin families.

The difference in overall height comes from the underlying nut-body style.

This is useful for buyers comparing product families.

Regular vs High vs Thin Selection

Requirement	Regular	High	Thin
General OEM Use	Common option	Application-specific	Application-specific
Overall Height	Medium	Greater	Lower
Space Requirement	Normal	Greater	Reduced
Nut Body Style	Style 1 basis	Style 2 basis	Style 0 basis
Coarse ISO Family	ISO 7040	ISO 7041	ISO 10511
Selection	Joint-specific	Joint-specific	Joint-specific

Do not substitute between these families only because the thread matches.

Thin Nyloc Nut Selection Requires Extra Care

A thin nut provides reduced body height.

That can be useful when:

Axial space is limited
Equipment is compact
The drawing specifically requires a thin design

But reduced height changes the mechanical behaviour and available thread engagement.

Do not use a thin nut simply to reduce cost or save space without engineering review.

Fine-Pitch Nyloc Nut Sizes

Not every Nyloc nut uses a coarse metric thread.

ISO 10512:2025 covers:

Prevailing torque hexagon regular nuts with non-metallic insert, with fine pitch thread.

Its scope includes metric fine-pitch threads from nominal diameter 8 mm to 39 mm, in steel and stainless steel, with product grades A and B.

Fine-Pitch Thread Example

A buyer may encounter:

M12 × 1.75 — common coarse pitch

and:

M12 × 1.5 — fine pitch example

These are not interchangeable.

Both the nut and bolt must have the same approved thread.

Fine Thread Is Not Automatically Better

Fine-pitch threads can be useful for certain engineered joints, but do not claim that they are universally:

Stronger
More vibration resistant
More precise
Better for automotive

The application and joint design should determine thread pitch.

Current ISO Standards for Nyloc-Type Nuts

Standard	Product	Thread
ISO 7040:2025	Regular non-metallic-insert prevailing-torque nut	Coarse
ISO 7041:2025	High non-metallic-insert prevailing-torque nut	Coarse
ISO 10511:2025	Thin non-metallic-insert prevailing-torque nut	Coarse
ISO 10512:2025	Regular non-metallic-insert prevailing-torque nut	Fine
ISO 2320:2015	Functional properties for prevailing-torque steel nuts	Coarse + fine within scope

ISO 2320:2015 was reviewed and confirmed in 2025, so it remains current.

Product Standard vs Functional Standard

This is important for OEM procurement.

Product Standard

Defines the characteristics of the particular nut family.

Examples:

ISO 7040
ISO 7041
ISO 10511
ISO 10512

Functional Standard

ISO 2320 addresses functional properties of prevailing-torque steel nuts within its defined scope.

A nut can look dimensionally correct but still require functional verification.

What Does ISO 2320 Cover?

ISO 2320:2015 covers functional properties for prevailing-torque steel nuts under its specified test conditions.

Its scope includes:

All-metal prevailing-torque nuts
Non-metallic-insert prevailing-torque nuts
Coarse threads M5–M39
Fine threads M8 × 1 to M39 × 3

within its other specified thread and mechanical-property conditions.

Important M3 and M4 Distinction

ISO 7040:2025 and ISO 10511:2025 include product designs down to M3.

However, ISO 2320’s stated coarse-thread functional scope begins at M5.

Therefore, buyers should not automatically apply ISO 2320 M5–M39 functional criteria to M3 or M4 products.

This is exactly why the product standard and functional standard should be checked separately.

Product Grade A and B

The current ISO 7040, 7041, 10511 and 10512 product standards specify product grades A and B within their scopes.

Product grade relates to dimensional/product requirements.

It should not be confused with:

Property class
Material grade
Stainless grade
Insert grade

Product Grade vs Property Class

Product Grade

Deals with product/dimensional accuracy requirements.

Property Class

Deals with specified mechanical properties.

They are not the same.

An RFQ should not state only:

Grade A Nyloc nut

when the buyer actually means a mechanical property class.

Nyloc Nut Materials

The current ISO product families discussed above include both:

Steel
Stainless steel

within their specified scopes.

The correct material should follow:

Mechanical Requirement + Corrosion + Temperature + Mating Bolt + OEM Specification

Steel Nyloc Nuts

Steel Nyloc nuts can suit many:

Automotive
Machinery
Equipment
Automation

applications.

The buyer should additionally define:

Mechanical/property requirement
Coating
Corrosion requirement
Functional requirement

Stainless Steel Nyloc Nuts

Stainless can be selected for suitable corrosion-resistant applications.

Important considerations include:

Stainless grade/property requirement
Mating bolt
Galling
Environment
Insert limitations
Cost

Do not assume:

Stainless = A4/316.

Stainless Mechanical Properties

The current ISO product standards note that, where applicable, stainless grades can be selected from ISO 3506-2.

The actual grade must still be specified according to the application.

Steel Nut Mechanical Properties

Current product-standard notes reference ISO 898-2 for applicable steel-nut property classes where other specifications are requested.

Do not assign a mechanical property class solely from nut size.

Nyloc Nut Insert

The non-metallic insert is the defining functional feature.

Its purpose is to interact with the bolt thread and create prevailing torque.

Important insert characteristics can include:

Material
Geometry
Position
Retention
Temperature behaviour
Chemical compatibility

Is the Insert Always Nylon?

“Nyloc” and “nylon insert lock nut” are widely used commercial terms.

However, technical ISO terminology is:

Non-metallic insert

That terminology is safer for standards-based specification because the exact insert material can be product/manufacturer-specific.

Insert Colour

Insert colours can include various shades depending on supplier and product.

Do not use colour as a universal indicator of:

Material
Temperature rating
Property class
Prevailing torque
Quality level

Use the technical specification.

Insert Height and Overall Nut Height

Current ISO standards distinguish:

Basic Nut-Body Height + Prevailing-Torque Feature Height = Overall Product Height

This explains why a Nyloc-type nut is taller than the underlying basic nut-body geometry.

Exact dimensions should come from the controlled standard or drawing.

Nyloc Nut Dimensions and Tool Access

Before selecting the nut, check:

Socket size
Wrench access
Nut height
Nearby components
Bolt protrusion
Installation tool

This matters in compact automation and machinery.

Automated Assembly Clearance

An automatic nut runner may require more space than a hand wrench.

Therefore:

Nut Dimensions + Socket Dimensions + Tool Clearance

should be reviewed during equipment design.

Bolt Length Selection

Bolt length should provide sufficient engagement through the nut and locking feature according to the approved joint design.

Too short can create inadequate engagement.

Too long can cause:

Interference
Excess projection
Safety/packaging problems

Do not use a universal exposed-thread rule for every assembly.

Mating Bolt Compatibility

Always check:

Nut Thread ↔ Bolt Thread

and:

Nut Mechanical Requirement ↔ Bolt Mechanical Requirement

plus:

Nut Coating ↔ Bolt Coating

The locking feature interacts directly with the bolt thread.

Bolt Thread Quality Matters

A damaged or uncontrolled bolt can change:

Prevailing torque
Installation torque
Insert wear
Removal behaviour

For functional qualification, use an approved or controlled mating fastener.

Nyloc Nut Surface Finishes

Possible steel-nut coating systems can include suitable:

Zinc electroplating
Zinc-flake coatings
Other customer-specified finishes

Selection should consider:

Corrosion
Friction
Thread fit
OEM requirement
Prevailing-torque behaviour

Coating Changes Assembly Behaviour

Coating can influence:

Thread friction
Bearing friction
Thread dimensions
Surface interaction

Therefore:

Changing coating can change tightening behaviour.

Do not transfer a validated tightening process blindly from one coating system to another.

Coating and Prevailing Torque

The locking feature interacts with the coated or finished bolt thread.

Therefore, bolt coating can also influence measured prevailing torque.

Functional validation should represent production conditions where required.

Nyloc Nut Temperature

Temperature is a major selection factor because the locking feature contains a non-metallic insert.

ISO 2320 states that non-metallic-insert nuts conforming to its requirements are used in applications ranging from −50 °C to +120 °C, while also warning that temperature influences functional properties.

This should not be converted into a universal temperature rating for every commercial Nyloc nut.

Why the Temperature Range Needs Context

ISO 2320’s functional tests themselves are specified at an ambient range of +10 °C to +35 °C.

Actual suitability still depends on:

Product
Insert material
Service exposure
Thermal cycling
Chemicals
OEM requirements

High-Temperature Applications

For temperatures outside the validated capability of the non-metallic insert, an all-metal prevailing-torque nut may need evaluation.

Do not automatically specify Nyloc nuts near:

Exhaust systems
Furnaces
High-temperature process equipment

without reviewing the actual thermal environment.

Chemical Exposure

A Nyloc nut used in industrial equipment may contact:

Oil
Coolant
Fuel
Cleaning agents
Hydraulic fluids
Process chemicals

Compatibility should be checked against the actual insert material.

Prevailing Torque

Prevailing torque is rotational resistance created by the locking feature.

It is not the same as:

Tightening torque
Clamp load
Proof load
Joint strength

This distinction is essential for engineering selection.

ISO 2320 Laboratory Conditions

ISO 2320 explicitly notes that its specified prevailing-torque values are based on laboratory test conditions and that actual prevailing torque in practical applications can vary.

Therefore, do not treat one catalogue value as a guaranteed production-assembly torque.

Nyloc Nut Tightening

A Nyloc nut still requires the correct joint tightening process.

Conceptually, the installation tool experiences effects from:

Prevailing Torque + Thread Friction + Bearing Friction + Clamp-Load Generation

The actual relationship depends on the joint.

No Universal Torque Chart

Do not publish generic statements such as:

M8 Nyloc Nut = X Nm

without defining:

Bolt property
Nut property
Coating
Lubrication
Friction
Joint
Required preload

Torque should follow the approved engineering specification.

Nyloc Nut Reuse

Repeated installation can change the locking feature’s behaviour.

Therefore:

Reuse should not be assumed.

The OEM or maintenance specification should define whether reuse is allowed and what functional acceptance criteria apply.

No Universal Reuse Count

Avoid statements such as:

Nyloc nuts can be reused five times.

There is no universal count that applies to every product and application.

Nyloc Nut Size Selection by Industry

Automotive

Check:

Thread + Standard + Mechanical Properties + Coating + Temperature + Prevailing Torque + PPAP

Machinery

Check:

Load + Vibration + Bolt + Temperature + Oil/Coolant + Maintenance

Equipment

Check:

Joint + Corrosion + Service Access + Locking Requirement

Automation

Check:

Thread + Prevailing-Torque Consistency + Tool Access + Cycle Time + Tightening Strategy

Automotive Nyloc Nut Sizes

Automotive applications may use different sizes depending on the component.

Do not create a rule such as:

M6 = automotive interior
M10 = chassis

Vehicle design and OEM specifications vary.

Use the actual drawing.

Machinery Nyloc Nut Sizes

Machinery applications should select the thread from the joint load and bolt requirement first.

Then choose the appropriate locking-nut family.

Do not increase nut size merely because the machine vibrates.

Automation Nyloc Nut Sizes

Automation systems may place additional importance on:

Tool access
Run-down behaviour
Prevailing-torque consistency
Cross-thread detection
Cycle time

A technically acceptable nut can still create production problems if functional variation is excessive.

Nyloc Nut vs All-Metal Lock Nut

Factor	Non-Metallic Insert	All-Metal
Locking Feature	Non-metallic insert	Metallic deformation/geometry
Temperature	Insert must be evaluated	Often considered for higher-temperature use
Chemical Compatibility	Insert important	Different considerations
Prevailing Torque	Product-specific	Product-specific
Reuse	Validate	Validate
Selection	Application-specific	Application-specific

Neither is universally better.

Nyloc Nut vs Standard Hex Nut

A standard hex nut normally does not contain a prevailing-torque feature.

If an OEM changes from a standard nut to a Nyloc-type nut, review:

Tightening
Bolt length
Clearance
Temperature
Tooling
Reuse
Cost

Do not treat it as a simple drop-in change.

Common Nyloc Nut Selection Mistakes

Avoid:

Ordering only by M-size.
Ignoring thread pitch.
Mixing regular, high and thin designs.
Assuming all insert colours mean the same thing.
Ignoring bolt mechanical properties.
Ignoring bolt coating.
Using generic torque charts.
Assuming unlimited reuse.
Calling the nut vibration proof.
Ignoring temperature.
Ignoring chemical exposure.
Approving only by dimensions.
Assuming stainless means 316.
Using ISO 2320 criteria outside its scope without review.

Nyloc Nut Selection Workflow

Use:

Step 1

Define the application.

Step 2

Identify the mating bolt.

Step 3

Select thread diameter.

Step 4

Select pitch.

Step 5

Choose regular/high/thin design.

Step 6

Identify product standard.

Step 7

Specify nut mechanical properties.

Step 8

Select material.

Step 9

Define insert requirement where necessary.

Step 10

Select coating.

Step 11

Check temperature and chemicals.

Step 12

Define prevailing-torque requirements.

Step 13

Define tightening process.

Step 14

Validate samples in the real assembly.

Nyloc Nut RFQ Checklist

Provide:

☐ Product standard
☐ Standard edition where controlled
☐ Thread diameter
☐ Thread pitch
☐ Regular/high/thin type
☐ Nut dimensions if custom
☐ Material
☐ Mechanical/property requirement
☐ Insert specification if required
☐ Coating
☐ Mating bolt
☐ Bolt coating
☐ Service temperature
☐ Chemical exposure
☐ Prevailing-torque requirement
☐ Tightening requirement
☐ Reuse policy
☐ Testing
☐ PPAP/documentation
☐ Quantity
☐ Annual demand

Example: Automotive RFQ

Product: Nylon Insert Lock Nut
Thread: M8 × 1.25
Product Type: Regular
Standard: Applicable ISO/customer drawing
Mechanical Requirement: Customer specification
Coating: OEM specification
Mating Bolt: Drawing attached
Prevailing Torque: Customer functional requirement
Temperature: Application data attached
PPAP: Required
Annual Quantity: 1,000,000 pcs

Example: Machinery RFQ

Product: Nyloc Lock Nut
Thread: M10 × 1.5
Nut Type: Regular non-metallic-insert prevailing-torque nut
Material/Mechanical Requirement: Drawing attached
Finish: Specification attached
Mating Bolt: Attached
Environment: Industrial machinery with oil exposure
Testing: Prevailing-torque testing required
Quantity: 250,000 pcs/year

What Are Common Nyloc Nut Sizes?

Common Nyloc Nut Sizes include M3, M4, M5, M6, M8, M10, M12, M14 and M16, with larger sizes available under applicable product standards. The correct nut must also be selected by pitch, product type, mechanical properties and standard.

What Standard Covers Nyloc Nut Sizes?

Current standards include ISO 7040:2025 for regular coarse-thread non-metallic-insert nuts, ISO 7041:2025 for high coarse-thread nuts, ISO 10511:2025 for thin coarse-thread nuts and ISO 10512:2025 for regular fine-pitch nuts.

What Is the Difference Between Regular and Thin Nyloc Nuts?

A regular Nyloc nut uses a standard style-1 nut-body basis, while a thin Nyloc nut uses a reduced style-0 nut-body basis. This changes overall height and mechanical behaviour, so they should not be substituted only because the thread matches.

Are Fine-Pitch Nyloc Nuts Available?

Yes. ISO 10512:2025 covers regular non-metallic-insert prevailing-torque nuts with metric fine-pitch threads from nominal diameter 8 mm to 39 mm within its scope.

What Is the Temperature Range for Nyloc Nuts?

ISO 2320 notes applications from −50 °C to +120 °C for conforming non-metallic-insert prevailing-torque steel nuts within its scope, but temperature affects functional behaviour. The specific product and service environment must still be validated.

Can Nyloc Nuts Be Reused?

Reuse should not be assumed. Repeated installation can change prevailing-torque behaviour, so the applicable product requirements, OEM maintenance policy and functional acceptance criteria should determine reuse.

Does Nyloc Nut Size Determine Tightening Torque?

No. Tightening torque also depends on the mating bolt, mechanical properties, coating, lubrication, friction, joint design and required preload. Do not select tightening torque from Nyloc Nut Size alone.

Is a Nyloc Nut Vibration Proof?

No. A Nyloc-type nut provides prevailing torque that can help resist unintended rotation, but joint performance still depends on preload, vibration, temperature, mating components and installation.

Questions Buyers Should Ask Before Ordering

Ask:

What Nyloc Nut Size is required?
Coarse or fine pitch?
Regular, high or thin?
Which product standard?
Steel or stainless?
What mechanical requirement?
What insert requirement?
Which coating?
What mating bolt?
What bolt coating?
What temperature?
Any chemical exposure?
What prevailing torque is required?
Is reuse allowed?
What testing is required?
Is PPAP required?

Before approving Nyloc Nut Sizes, confirm:

Thread + Pitch + Nut Type + Standard + Dimensions + Material + Mechanical Requirement + Insert + Coating + Bolt + Temperature + Prevailing Torque + Testing

Nyloc Nut Size Is Only the Starting Point

Choosing the correct Nyloc Nut Sizes begins with the mating bolt, but it should not end there.

The complete engineering sequence is:

Thread → Pitch → Nut Type → Standard → Dimensions → Mechanical Properties → Material → Insert → Coating → Bolt → Temperature → Prevailing Torque → Tightening → Testing

An M8 or M10 Nylon Insert Lock Nut can have the correct thread and still be unsuitable if:

The wrong nut family is selected.
Mechanical properties do not match the bolt.
Temperature exceeds validated conditions.
The insert is chemically incompatible.
Coating changes assembly behaviour.
Prevailing torque is outside the required range.
Tightening does not produce the required joint condition.
Reuse is uncontrolled.

For automotive, machinery, equipment and automation applications, buyers should qualify the complete nut-bolt-joint system, not only the thread size.

Rajal Industries can evaluate standard and customer drawing-based Nyloc Lock Nut and non-metallic-insert Locking Nuts for OEM applications, subject to technical feasibility, manufacturing process, tooling and sample validation.

Need Help Selecting Nyloc Nut Sizes?

Send Rajal Industries:

Drawing + Thread + Pitch + Product Standard + Nut Type + Material + Mechanical Requirement + Insert Requirement + Coating + Mating Bolt + Temperature + Prevailing-Torque Requirement + Testing + Quantity

for technical feasibility and quotation review.