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What is the difference between metric and standard fasteners?

clock 30 minutes | 25 Aug 2021

various screws, washers and wall plugs

Depending on the context, “standard” often refers to U.S. fasteners. This typically means we’re talking about measuring units in inches, whereas metric is exactly that: measurements based on metric units, such as millimetres. Keep in mind, however, the U.S. is now producing fasteners using the metric system.

The other definition of standard is the set of specifications as defined by organisations, which we’ll talk about below.

Metric vs standard

The major difference between metric and standard is in how threads are specified. Standard fasteners are either Unified National Coarse Thread (UNC) or Unified National Fine Thread (UNT). Standard metric threads, meaning ISO metric threads in this case, are not specified this way, though they are comparable to UNC threads.

Standard metric screw threads are designated by pitch in millimetres (mm). This is the distance measured between the peaks of two adjacent threads. ASTM fastener standards measure threads by TPI: threads per inch. You literally just count the number of threads that cover a one-inch distance.

the various parts of a fastener thread

Metric screw sizes vs standard

Metric and standard sizes are communicated differently. Standard metric screw dimensions are determined by the pitch and the major diameter, which as the illustration shows, is the largest diameter of the screw.

Let’s say it’s 4mm, in which case it appears as M4 (the M means metric). Now let’s say the pitch is 1mm. The size of your screw is M4 x 1mm.

Let’s consider standard bolt sizes.For fasteners measured in inches, take the nominal major diameter and the threads per inch. For example, a 5/8-11 (coarse) thread means the nominal major diameter is 5/8"and the 11 means 11 threads per inch.

fastener pitch showing major diameter

Metric vs standard chart

Metric or standard? Here’s how they compare:

Inches

Metric Size- Pitch, ISO and IFI Rec.

(UNC)

(UNF)

1- 64

1- 72

M2 x 0.4

3- 48

3- 56

M2.5 x 0.45

4- 40

4- 48

M3 x 0.5

6- 32

6- 40

M3.5 x 0.6

8- 32

8- 36

M4 x 0.7

10- 24

10- 32

M5 x 0.8

1/4- 20

1/4- 28

M 6x 1

5/16-18

5/16- 24

M8 x 1.25

3/8-16

3/8- 24

M10 x 1.5

7/16-14

7/16- 20

M12 x 1.75

1/2- 13

1/2- 20

M14 x 2

5/8- 11

5/8- 18

M18 x 2

3/4- 10

3/4- 16

M20 x 2.5

1- 8

1-12

M24 x 3

1-1/4- 7

1-1/8- 12

M30 x 3.5

1-1/2- 6

1-1/4- 12

M36 x 4

Fastener standards organizations

Standards are necessary to enable us to specify, test and assess fasteners’ properties. These are the organizations we’re covering in this article:

  • ASTM International: Formerly known as the American Society for Testing and Materials, and informally called ASTM. They are a worldwide recognized leader in developing international standards. ASTM bolt standards and other fasteners almost always appear as ASTM/ASNI.
  • ASME: The American Society for Testing and Materials. ASME is sometimes confused with ASTM. ASTM issues standards on material properties and testing, while ASME issues standards for materials to be used in construction and infrastructure.
  • ANSI: American National Standards Institute. While ANSI does not develop standards, they oversee organizations that do.
  • ISO: International Organization of Standardization, the world’s largest developer of international standards. The ISO standard lists are extensive, from ISO 4762 standard to ISO 7046 specifications.
  • BSI: The British Standards Institution, along with ANSI, is a member of the ISO.

American flag to show US fastener standards

U.S. standards

Standards include ASTM/ANSI and ASME. You’ll notice in the STANDARD column that sometimes the letter M proceeds a standard. The M stands for metric. This is also spelled out in the THREAD column.

STANDARD

DESCRIPTION

THREAD

MATERIAL

A320L7

L7 Stud Bolt with Nut A320

UNC

Steel

A320L7

Stud Bolt

UNC

Stainless-Steel

ASTMA193

B7 Stud Bolt with Nut A194 2H

UNC

Steel

ASTMA193

Stud Bolt B8M with Nut A194 8M

UNC

Stainless-Steel

B1.20.3

Socket Taper Pressure Pipe Plugs

NPTF 3/4 Taper

Alloy Steel

Stainless-Steel

Brass

B1.20.3

Socket Taper Pressure Pipe Plugs

NPTF 7/8 Taper

Alloy Steel

B1.5

Allthread ACME

Inch

Grade-5.8

Stainless-Steel-A2

B1.5

Round Flange Track Nut ACME

Round Track Nut ACME

Inch

Steel

B16.5

Flange Bolt

UNC

SAE-5(8.8)

SAE-8(10.9)

B18.15

Lifting Eye Nut Forged Type A

UNC

Steel

B18.151A

Eye Bolt Forged No Shoulder Type A

UNC

Steel

B18.151B

Eye Bolt Forged No Shoulder Type B

UNC

Steel

B18.152A

Lifting Eye Bolt Forged with Shoulder Collar

UNC

Steel

B18.152B

Lifting Eye Bolt Forged with Shoulder Collar

UNC

Steel

B18.16.3M

Nylon Insert Flange Self Locking Nut

UNC

Steel

B18.2.1

Hexagon Head Bolt

Hexagon Head Set Screw

External Torx Bolt with Flange

UNC

SAE-5(8.8)

SAE-8(10.9)

B18.2.1

External Torx Bolt with Flange

UNC

Stainless-Steel 18/8-304-A2

Stainless-Steel 18/10-316-A4

B18.2.1

Hexagon Head Bolt

Hexagon Head Set Screw

UNF

SAE-5(8.8)

SAE-8(10.9)

B18.2.1.1T10

Internal External Toothed Shakeproof Washer

Inch

Spring-Steel

B18.2.1.1T6

Internal Toothed Shakeproof Washer

Inch

Spring-Steel

B18.2.1.1T7

Internal Toothed Heavy Shakeproof Washer

Inch

Spring-Steel

B18.2.1.1T9

Countersunk External Toothed Shakeproof Washer

Inch

Spring-Steel

B18.2.1.1T10

Square Head Bolt

UNC

SAE-5(8.8)

SAE-8(10.9)

Mild Steel A-A563

Stainless-Steel 18/8-304-A2

Stainless-Steel 18/10-316-A4

B18.2.2

Hexagon Full Nut

Hexagon Heavy Lock Nut

Hexagon Heavy Nut

Hexagon Lock Nut

UNC

SAE-5(8.8)

SAE-8(10.9)

Stainless-Steel 18/10-316-A4

B18.2.2

Hexagon Full Nut

Hexagon Heavy Lock Nut

Hexagon Heavy Nut

Hexagon Lock Nut

Hexagon Machine Screw Nut

Hexagon Allthread Coupling Connector 3D

UNC

Mild Steel A-A563

Stainless-Steel 18/8-304-A2

B18.2.2

Hexagon Heavy Nut

Hexagon Allthread Coupling Connector 3D

UNC

Steel-A194-2H

Steel C-A563

B18.2.2

Hexagon Allthread Coupling Connector 3D

UNC

Dh-Steel

Brass

B18.2.2

Hexagon Structural Heavy Full Nut

Slotted and Castle Hexagon Nut

Slotted Hexagon Heavy Nut

Slotted Hexagon Heavy Nut

UNC

Steel

B18.2.2

Hexagon Full Nut

Hexagon Heavy Lock Nut

Hexagon Heavy Nut

Hexagon Lock Nut

UNF

SAE-5(8.8)

SAE-8(10.9)

Mild Steel A-A563

B18.2.2

Hexagon Heavy Nut

UNF

Steel-A194-2H

Steel C-A563

B18.2.2

Hexagon Full Nut

Hexagon Heavy Lock Nut

Hexagon Heavy Nut

Hexagon Lock Nut

UNF

Stainless-Steel 18/8-304-A2

Stainless-Steel 18/10-316-A4

B18.2.2

Hexagon Full Nut

Hexagon Heavy Lock Nut

Hexagon Heavy Nut

Left HandUNC

SAE-8(10.9)

B18.2.2

Hexagon Full Nut

Hexagon Heavy Lock Nut

Hexagon Heavy Nut

Hexagon Lock Nut

Left HandUNF

SAE-5(8.8)

SAE-8(10.9)

Mild Steel A-A563SAE-5(8.8)

Mild Steel A-A563

B18.2.2

Square Heavy Nut

UNC

Steel

B18.2.2T1

Square Nut

UNC

Steel

B18.2.5M

12 Point Flange Head Bolt

Metric Coarse

Grade-8.8

Grade-10.9

Grade-12.9

Stainless-Steel-A2

Stainless-Steel-A4

B18.2.6

Hexagon Head Twist Off Tension Control Bolt

Round Head Twist Off Tension Control Bolt

UNC

Steel-A325

B18.21.1

Single Coil Square Section Spring Washer

Double Coil Rectangular Section Spring Washer

External Toothed Heavy Shakeproof Washer

Inch

Spring-Steel

B18.21.1T1

Single Coil Regular Section Spring Washer

Inch

Spring-Steel

B18.21.1T2

Washer Spring, Heavy

Inch

Spring-Steel

B18.21.1T3

Washer Spring, Extra Duty

Inch

Spring-Steel

B18.21.1T4

Washer Spring, Hi Collar

Inch

Spring-Steel

B18.21.1T8

External Toothed Shakeproof Washer

Inch

Spring-Steel

B18.22.1

Narrow Washer Table 2B

Regular Washer Table 2B

SAE Narrow Washer Table 1A

USS Wide Washer Table 1A

Wide Washer Table 2B

Inch

Steel

Stainless-Steel 18/8-304-A2

B18.22.1

Thin Washer Table 1B

Inch

Steel

B18.22M

American Flat Washer Narrow

American Flat Washer Regular

American Flat Washer Wide

Metric

Steel

Stainless-Steel 18/8-304-A2

B18.3

Socket Cap Screw 1960

UNF

Grade-12.9, Rc38/43

B18.3

Socket Set Screw Cone Point

Socket Set Screw Cup Point

Socket Set Screw Dog Point

Socket Set Screw Flat Point

Socket Set Screw Full Dog Point

Socket Set Screw Oval Point

Socket Set Screw Tip Brass

Socket Set Screw Tip Nylon

UNC

Grade-14.9-45H

B18.3

Low Head Socket Cap Screw

UNC

Steel

B18.3

Socket Button Head Screw

Socket Countersunk Screw

Hexagon Socket Shoulder Screw

Splined Socket Button Head Screw

Spline Socket Countersunk Screw

Torx Socket Button Head Screw

Torx Socket Countersunk Screw

UNC

UNF

Grade-12.9

B18.3

Socket Cap Screw 1960

UNC

Grade-12.9, Rc38/43

B18.3

Hexagon Socket Shoulder Screw

UNC

Stainless-Steel

B18.3

Low Head Socket Cap Screw

UNC

Stainless-Steel 18/10-316-A4

B18.3

Socket Cap Screw 1960

Socket Button Head Screw

Socket Countersunk Screw

UNC

Stainless-Steel 18/8-304-A2

Brass

Aluminium

Monel

Nylon-66

Phospher-Bronze

B18.3

Socket Set Screw Tip Silver

Socket Flange Cap Screw

UNC

Steel

B18.3

Hexagon Keys Long Arm

Hexagon Keys Short Arm

Inch

Steel

Alloy Steel

B18.3

Socket Set Screw Cone Point

Socket Set Screw Cup Point

Socket Set Screw Dog Point

Socket Set Screw Flat Point

Socket Set Screw Full Dog Point

UNF

Grade-14.9-45H

B18.3

Socket Cap Screw 1960

Socket Button Head Screw

Socket Countersunk Screw

UNF

Stainless-Steel 18/10-316-A4

Brass

Aluminium

Monel

Nylon-66

Phosphor-Bronze

B18.3.3M

Hexagon Socket Shoulder Screw f9

Metric Coarse

Grade-12.9

Stainless-Steel

B18.31M

Engineers Stud Metal End =1.1/2 D

Metric Coarse

Steel

B18.5

Rib Neck Carriage Bolt

Cup Square Neck Carriage Bolt

UNC

SAE-5(8.8)

B18.5

Cup Square Neck Carriage Bolt Full Thread

UNC

SAE-8(10.9)

B18.6.2

Square Head Set Screw Cone Pt

Square Head Set Screw Cup Point

Square Head Set Screw Half Dog Pt

Square Head Set Screw Flat Pt

Square Head Set Screw Oval Pt

UNC

Case Hardened Steel

B18.6.2

Square Head Set Screw Cup Point

UNC

Alloy Steel

Stainless-Steel

B18.6.2

Slotted Grub (Set) Screw Flat Point

UNC

Grade-14.9-45H

B18.6.2

Square Head Set Screw Cup Point

UNF

Case Hardened Steel

B18.6.2

Slotted Grub (Set) Screw Flat Point

UNF

Grade-14.9-45H

B18.6.3

Phillips Pan Head Screw

Phillips Raised Countersunk Machine Screw

Phillips Raised Trim Countersunk Machine Screw

Slotted Cheese Head Machine Screw

Phillips Countersunk Head Machine Screw

Phillips 100 Deg Countersunk Head Machine Screw

Phillips Trim Countersunk Head Machine Screw

Slotted 100 Deg Countersunk Head Machine Screw

Slotted Countersunk Head Machine Screw

Slotted Pan Head Machine Screw

UNC

Grade-4.8

B18.6.3

Square Machine Screw Nut

UNC

Mild Steel A-A563

Stainless-Steel-A2

Brass

B18.6.3

Slotted 100 Deg Countersunk Machine Screw

Slotted Raised CountersunkMachine Screw

Slotted Raised Countersunk Trim Machine Screw

Pozi Raised Countersunk Machine Screw

Pozi Raised Countersunk Trim Machine Screw

Slotted Mushroom Head Machine Screw

Phillips Mushroom Head Machine Screw

Pozi Countersunk Head Machine Screw

Pozi 100 Deg Countersunk Head Machine Screw

Pozi Trim Countersunk Head Machine Screw

Slotted Binding Head Machine Screw

Pozi Binding Head Machine Screw

Phillips Binding Head Machine Screw

Pozi Raised Cheese Head Machine Screw

Pozi Flange Pan Head Machine Screw

Hexagon Head Machine Screw

Hexagon Head Machine Screw Large Head

Hexagon Head Slotted Machine Screw

Hexagon Head Pozi Machine Screw

Hexagon Head Phillips Machine Screw

Hexagon Large Head Slotted Machine Screw

Hexagon Large Head Pozi Machine Screw

Hexagon Large Head Phillips Machine Screw

Hexagon Washer Head Machine Screw

Hexagon Washer Head Slotted Machine Screw

Hexagon Washer Head Pozi Machine Screw

Hexagon Washer Head Phillips Machine Screw

Pozi Mushroom Head Machine Screw

Pozi Pan Head Machine Screw

Pozi Pan Washer Head Machine Screw

Pozi Round Head Machine Screw

Pozi Round Washer Head Machine Screw

UNC

Grade-4.8

B18.6.4

Pozi Pan Head Self Tapping Screw AB

Inch

Case Hardened Steel

B18.6.9A

Wing Nut, American Type A

UNC

Steel Cold Forged

Stainless-Steel 18/8-304-A2

Stainless-Steel 18/10-316-A4

Brass

Steel Cold Forged

B18.6.9B1

Wing Nut, Mickey Mouse B1

UNC

Steel Cold Forged

Stainless-Steel 18/8-304-A2

Stainless-Steel 18/10-316-A4

Brass

B18.6.9B2

Wing Nut, Mickey Mouse Tall B2

UNC

Steel Cold Forged

Stainless-Steel 18/8-304-A2

Stainless-Steel 18/10-316-A4

Brass

B18.6.9C1

Wing Nut, American Type C1 Die Cast

UNC

Die Cast Zinc-Alloy

B18.6.9C2

Wing Nut, American Type C2 Die Cast

UNC

Die Cast Zinc-Alloy

B18.6.9C3

Wing Nut, American Type C3 Die Cast

UNC

Die Cast Zinc-Alloy

B18.6.9D1

Wing Nut, American Type D1 Stamped

UNC

Steel

B18.6.9D2

Wing Nut, American Type D2 Stamped

UNC

Steel

B18.6.9D3

Wing Nut, American Type D3 Stamped

UNC

Steel

B18.8.1

Split Cotter Pin

Inch

Steel

B18.8.2

Parallel Dowel Pin

Inch

Hardened & Ground Steel

B18.8.2

Spring Tension Pin Slotted

Inch

Spring-Steel

Stainless-Steel

B18.8.2

Parallel Dowel Pin

Inch

Stainless-Steel

B18.8.2Coil

Coiled Roll Spring Tension Pin Heavy Duty

Coiled Roll Spring Tension Pin Light Duty

Coiled Roll Spring Tension Pin Standard

Inch

Spring-Steel

Stainless-Steel

B18.9

Countersunk Nib Bolt

UNC

SAE-8(10.9)

B18.9

Domed Countersunk Square Plow Bolt #3

UNC

SAE-5(8.8)

SAE-8(10.9)

B18.9

Countersunk Square Plow Bolt

UNC

SAE-5(8.8)

SAE-8(10.9)

Grade-A(4.6)

How do ISO standards compare?

Within the U.S., the metric system vs standard scenario can now be phrased as the metric system vs. metrics. ANSI is known for the imperial system, but also has metric standards, which differ slightly from ISO metric standards. The U.S. isn’t alone in converting to ISO with little enthusiasm. The Germans, who use their own metric standards (DIN), aren’t too excited either. The cost to convert is enormous when equipment and infrastructure are measured in the home system, so the reluctance is understandable. Still, if everyone wants more success exporting their products on the global stage, one metric standard for worldwide manufacturing is necessary.

The difference between these metric standards lies in the fasteners varying dimensional properties. These fastener specifications are slight. Yet these fasteners are interchangeable.

U.S. standards still require a pitch callout on coarse threads. Here’s how they compare to ISO designations:

ISO THREAD DESIGNATION

U.S. EQUIVALENT

M1.6

M1.6 x 0.35

M2

M2 x 0.4

M2.5

M2.5 x 0.45

M3

M 3x 0.5

M3.5

M3.5 x 0.6

M4

M4 x 0.7

M5

M5 x 0.8

M6

M6 x 1

M8

M8x1

M8 x 1.25

M8 x 1

M10

M10x1.25

M10 x 1.5

M10 x 1.25

M12

M12x1.25

M12 x 1.75

M12 x 1.25

M14

M14x1.5

M14 x 2

M14 x 1.5

M16

M16x1.5

M16 x 2

M16 x 1.5

M18

M18x1.5

M18 x 2.5

M18 x 1.5

M20

M20x1.5

M20 x 2.5

M20 x 1.5

M22

M22x1.5

M22 x 2.5

M22 x 1.5

M24

M24x2

M24 x 3

M24 x 2

M27

M27x2

M27 x 3

M27 x 2

M30

M30x2

M30 x 3.5

M30 x 2

M33

M33x2

M33 x 3.5

M33 x 2

M36

M36x3

M36 x 4

M36 x 3

M42

M42 x 4.5

M48

M48 x 5

M56

M56 x 5.5

M64

M64 x 6

M72

M72 x 6

M80

M80 x 6

M90

M90 x 6

M100

M100 x 6

flag of great Britain to show british fasteners

What are British standards?

Fasteners made to British standards are still in use, but they’re primarily for the fastener aftermarket. So, for example, BS 4168 fasteners are still out there, but they’re not as readily available as fasteners made to ISO standards. You can also find BS 4183 dimensions so rest assured, you can still get British Standard fasteners.

However, the BSI is in the process of adopting all European standards as British standards – prefixed BS EN or BS ISO – and withdrawing conflicting BS fasteners. The BS fastener standard for inch washers is still popular, but most British fasteners use ISO or DIN standards. DIN is the Deutsches Institut für Normung, the German national organization for standardization.

We’ll show you equivalencies between BS, DIN and ISO, but first, here are British Standards:

STANDARD

DESCRIPTION

THREAD

MATERIAL

BS 21

Socket Taper Pressure Pipe Plugs

BSPT 3/4 Taper

Alloy Steel

Stainless-Steel-A4

BS 57

Slotted Mushroom Head Machine Screw

Slotted Cheese Head Machine Screw

Pozi Countersunk Head Machine Screw

Slotted Countersunk Head Machine Screw

Slotted Raised Countersunk Machine Screw

Pozi Raised Countersunk Machine Screw

Slotted Pan Head Machine Screw

BA

Grade-4.8

BS 57

Hexagon Head Set Screw

BA

Grade-R

BS 57

Hexagon Head Set Screw

Hexagon Full Nut

Hexagon Lock Nut

BA

Grade-A-Steel

BS 57

Hexagon Head Set Screw

BA

Stainless-Steel-A2

BS 57

Hexagon Full Nut

Hexagon Lock Nut

BA

Stainless-Steel

BS 57

Hexagon Full Nut

BA

Brass

BS 57

Pozi Mushroom Head Machine Screw

Pozi Pan Head Machine Screw

Slotted Round Head Machine Screw

BA

Grade-4.8

BS 325

Cup Head Nib Bolt

BSW Whitworth

Grade-4.6

BS 325

Black Square Nut

BSW Whitworth

Class-4

BS 325

Hexagon Black Full Nut

BSW Whitworth

Grade-A-Steel

BS 325

Cup Square Neck Carriage Bolt with Nut

Countersunk Square Plow Bolt

Countersunk Long Square Plow Bolt For Wood

Oval Neck Cup Head Bolts

BSW Whitworth

Grade-4.6

BS 450

Slotted Mushroom Head Machine Screw

Slotted Cheese Head Machine Screw

Slotted Countersunk Head Machine Screw

Slotted Pan Head Machine Screw

Slotted Raised Countersunk Machine Screw

Slotted Raised Cheese Head Machine Screw

BSF

BSW Whitworth

Grade-4.8

BS 450

Pozi Countersunk Head Machine Screw

Pozi Raised Cheese Head Machine Screw

Pozi Raised Countersunk Machine Screw

Pozi Mushroom Head Machine Screw

Pozi Pan Head Machine Screw

Slotted Round Head Machine Screw

BSF

BSW Whitworth

Grade-4.8

BS 450

Slotted Round Head Machine Screw

BSW Whitworth

Brass

BS 856

Wing Nut Mickey Mouse Type DC

Wing Nut Type CF

BSF

BSW Whitworth

BA

Steel

Stainless-Steel

Brass

BS 1083

Hexagon Head Bolt

Hexagon Head Set Screw

BSW Whitworth

Grade-R

Stainless-Steel-A2

BS 1083

Hexagon Full Nut

Hexagon Lock Nut

BSW Whitworth

Grade-A-Steel

Stainless-Steel

BS 1083

Hexagon Lock Nut Thicker 3 Sizes

BSW Whitworth

BSF

Grade-A-Steel

Stainless-Steel

BS 1083

Slotted and Castle Hexagon Nut

BSW Whitworth

BSF

Steel

BS 1083

Hexagon Head Bolt

Hexagon Head Set Screw

BSF

Grade-R

Stainless-Steel-A2

BS 1083

Hexagon Full Nut

Hexagon Lock Nut

BSF

Grade-A-Steel

Stainless-Steel

BS 1210

Pozi Countersunk Twin Thread Wood Screw

Metric

Steel

BS 1210

Pozi Countersunk Wood Screw

Inch

Steel

BS 2470

Socket Cap Screw 1936

UNF

UNC

Grade-12.9

Stainless-Steel 18/8-304-A2

BS 2470

Hexagon Keys Short Arm

Inch

Alloy Steel

BS 2470

Socket Set Screw Cone Point

Socket Set Screw Cup Point

Socket Set Screw Dog Point

Socket Set Screw Flat Point

BSW Whitworth

BSF

BA

Grade-14.9-45H

BS 2470

Socket Cap Screw

Socket Countersunk Screw

Hexagon Socket Shoulder Screw

BSW Whitworth

Grade-X(12.9)

BS 2470

Socket Cap Screw

Socket Countersunk Screw

BSW Whitworth

BSF

Stainless-Steel 18/8-304-A2

BS 2470

Socket Cap Screw

Socket Countersunk Screw

BSF

BA

Grade-X(12.9)

Stainless-Steel 18/8-304-A2

BS 2693

Engineers Stud Metal End =1.1/2 D

BSF

BSW Whitworth

Steel

BS 3032

D Shackle Pins A

D Shackle Pins C

D Shackle Pins E

D Shackle Pins F with Forelock Pin

Inch

Steel

BS 3410

Inch Washer Table 1 BA

Inch Washer Table 2 BA

Inch Washer Table 3 Heavy

Inch Washer Table 3 Light

Inch Washer Table 4 Heavy

Inch Washer Table 4 Light

Inch Washer Table 5

Inch Washer Table 6

Inch Washer Table 7

Inch Washer Table 8

Inch Washer Table 9

Inch

Steel

Stainless-Steel

Brass

BS 3410

Inch Washer Table 1 BA

Inch

Nylon-66

BS 4162

Flange Bolt

Metric Coarse

Steel

BS 4168

Hexagon Socket Shoulder Screw f9

Metric Coarse

Grade-12.9

BS 4174

Slotted Countersunk Head Self Tapping Screw AB

Slotted Countersunk Head Self Tapping Screw B

Slotted Raised Countersunk Head Self Tapping Screw AB

Slotted Raised Countersunk Head Self Tapping Screw B

Hexagon Head Self Tapping Screw AB

Hexagon Head Self Tapping Screw B

Pozi Countersunk Head Self Tapping Screw AB

Pozi Countersunk Head Self Tapping Screw B

Pozi Pan Head Self Tapping Screw AB

Pozi Pan Head Self Tapping Screw B

Slotted Pan Head Self Tapping Screw AB

Slotted Pan Head Self Tapping Screw B

Inch

Case Hardened Steel

BS 4174

Round Hammer Drive Screw 'U'

Inch

Steel

Stainless-Steel-A2

Brass

Copper

BS 4183

Hexagon Machine Screw Nut

Metric Coarse

Steel

BS 4278

Lifting Eye Bolt Forged with Shoulder Collar

UNC

Steel

BS 4320

Form B Flat Washer

Form C Flat Washer

Form D Flat Washer

Form E Flat Washer

Form F Flat Washer

Form G Flat Washer

Table 6 Washer Greater Than M68

Metric

Steel

BS 4320

Form B Flat Washer

Form C Flat Washer

Form D Flat Washer

Form E Flat Washer

Form F Flat Washer

Form G Flat Washer

Metric

Stainless-Steel

BS 4320

Form B Flat Washer

Form C Flat Washer

Metric

Brass

Nylon-66

BS 4320

Form B Flat Washer

Metric

Aluminium

Polypropylene

Titanium

BS 4439

Engineers Stud Metal End =1.1/2 D 4H

Metric Coarse

Grade-8.8

Grade-10.9

Grade-12.9

Grade-4.6

Stainless-Steel

BS 4463

Double Dished (Wave) Crinkle Washer

Metric

Beryllium Copper

BS 4929

Nylon Insert Self Locking P-Type Thick Nut

UNC

UNF

Class-8

BS 4929

Nylon Insert Self Locking T Type Thin Nut

UNC

UNF

Class-8

BS 4933

Cup Square Neck Carriage Bolt with Nut

Metric Coarse

Steel

BS 7419

Square Square Holding Down Bolts

Metric Coarse

Grade-4.6

Grade-8.8

BS 1802A

Single Coil Square Section Spring Washer

Inch

Spring-Steel

Stainless-Steel

BS 1802A

Single Coil Square Section Spring Washer

BA

Spring-Steel

BS 1802B

Rectangular Section Spring Washer

Inch

Spring-Steel

Stainless-Steel

BS 1802B

Rectangular Section Spring Washer

BA

Spring-Steel

BS 1802D

Double Coil Rectangular Section Spring Washer

Inch

Spring-Steel

BS 3032T1

D Shackles Small with A Pin

Inch

Steel

BS 3032T2

D Shackles Large with A Pin

Inch

Steel

BS 3032T3

D Shackles Large Bow with A Pin

Inch

Steel

BS 3032T4

D Shackles Small Bow with A Pin

Inch

Steel

BS 3974G

U' Bolt Round Bend To Grip

Metric Coarse

Steel

Stainless-Steel

BS 3974NG

'U' Bolt Round Bend Not To Grip

Metric Coarse

Steel

Stainless-Steel

BS 4278T1

Lifting Eye Bolt Forged with Shoulder Collar

Metric Coarse

Steel

BS 4278T2

Link Eye Bolt Forged with Shoulder Collar

Metric Coarse

Steel

BS 4278T3

Dynamo Eye Bolt Forged with Shoulder Collar

Metric Coarse

Steel

BS 4278T4

Lifting Eye Bolt Forged with Shoulder Collar

BSW Whitworth

Steel

BS 4278T5

Link Eye Bolt Forged with Shoulder Collar

BSW Whitworth

UNC

Steel

BS 4278T6

Dynamo Eye Bolt Forged with Shoulder Collar

BSW Whitworth

UNC

Steel

BS 7670T3

Weld Screw 3 Nibs Under Head

Metric

Steel

BS 7670T4

Hexagon Weld Nut Standard Collar

Metric Coarse

Steel

BSP

Hexagon Pipe Lock Nut

Metric Coarse

Steel

Comparing DIN, ISO and British Standards

ISO 4762 vs DIN 912 – or are they the same? Is there a British equivalent for DIN 931? What’s DIN 934 or ISO 2340 equivalent to? What’s the din 6914 ISO equivalent? The chart below should help you answer these and other questions.

DIN Standard

ISO Standard

British Standard

Product

DIN 1

ISO 2339

Cone Pins, untempered

DIN 125

ISO 7089

Washers; medium type, primarily for hexagon bolts

DIN 125

ISO 7090

Washers; medium type, primarily for hexagon bolts

DIN 126

ISO 7091

Product grade C washers - designed for use with hexagon head bolts and nut

DIN 127

BS4464B

Spring lock washers with square ends or tang ends

DIN 128

Curved and wave spring lock washers

DIN 137

Spring washers, curved or wave

DIN 1440

ISO 8738

Medium type washers for pins

DIN 1443

ISO 2340

Clevis pins without head

DIN 1444

ISO 2341

Clevis pins with head

DIN 1470

ISO 8739

Grooved Pins, Full Length Parallel-grooved with Pilot

DIN 1471

ISO 8744

Grooved Pins, Full Length Taper-grooved

DIN 1472

ISO 8745

Grooved Pins, Half Length Taper-grooved

DIN 1473

ISO 8740

Grooved Pins, Full Length Parallel-grooved with Chamfer

DIN 1474

ISO 8741

Grooved Pins, Half Length Reverse-grooved

DIN 1475

ISO 8742

Grooved Pins, Third Length Centre-grooved

DIN 1476

ISO 8746

Round Head Grooved Pins

DIN 1477

ISO 8747

Countersunk Head Grooved Pins

DIN 1481

ISO 8752

Spring-Type Straight Pins (Roll Pins) - Heavy Type

DIN 1587

Hexagon domed cap nuts

DIN 1816

Round Nut with Set Pin Holes Inside; ISO Metric Fine Thread

DIN 315

Wing nuts with rounded wings

DIN 316

Wing screws with rounded wings

DIN 404

Slotted capstan screws

DIN 417

ISO 7435

Slotted set screws with long dog point

DIN 427

ISO 2342

Slotted headless screws with chamfered end

DIN 428

ISO 4034

Hexagon nuts, Grade C

DIN 433

ISO 7092

Washers for use with cheese head screws

DIN 433-1

ISO 7092

Product grade A washers - with a hardness up to 250 HV designed for use with cheese head screws

DIN 433-2

ISO 7092

Product grade A washers - with a hardness up to 300 HV designed for use with cheese head screws

DIN 438

ISO 7436

Slotted set screws with cup point

DIN 439

ISO 4035

BS3692

Hexagon thin nuts

DIN 439

ISO 4036

BS3692

Hexagon thin nuts

DIN 439

ISO 8675

BS3692

Hexagon thin nuts

DIN 439-1

ISO 4036

Unchamfered hexagon thin nuts - Product grade B

DIN 439-2

ISO 4035

Chamfered hexagon thin nuts - Product grades A and B

DIN 439-2

ISO 8675

Chamfered hexagon thin nuts - Product grades A and B

DIN 440

ISO 7094

Washers for use in timber constructions

DIN 444

Eyebolts

DIN 462

Machine Tools; Internal Tab Washers for Slotted Round Nuts for Hook Spanner according to DIN 1804

DIN 464

Knurled thumb screws, high type

DIN 466

Knurled nuts, high type

DIN 467

Knurled nuts, low type

DIN 471

Circlips (retaining rings) for shafts; Normal type and heavy type

DIN 479

Square head bolts with short dog point

DIN 5406

Lockwashers and locking plates for use with rolling bearings

DIN 548

Round nuts with set pin holes in side

DIN 551

ISO 4766

Slotted set screws with flat point

DIN 553

ISO 7434

Slotted set screws with cone point

DIN 555

ISO 4034

M5 to M100x6 hexagon nuts - Product grade C

DIN 558

ISO 4018

Hexagon head screws

DIN 580

Collar eyebolts for lifting purposes

DIN 601

ISO 4016

M5 to M52 hexagon head bolts; product grade C

DIN 603

Mushroom head square neck bolts

DIN 609

Hexagon fits bolts with long thread

DIN 6319

Spherical washers and conical seats

DIN 6325

ISO 8734

Parallel Pins, Hardened; Tolerance Zone m6

DIN 6340

Washers for clamping devices

DIN 653

Knurled thumb screws, low type

DIN 6797

Toothed lock washers

DIN 6798

Serrated lock washers

DIN 6799

Lock washers (retaining washers) for shafts

DIN 6900

ISO 10644

Screw and Washer Assemblies

DIN 6901

ISO 10510

Tapping screw and washer assemblies

DIN 6902

ISO 10673

Plain washers for screw and washer assemblies

DIN 6903

ISO 10669

Plain washers for tapping screw and washer assemblies

DIN 6912

Hexagon socket thin head cap screws with pilot recess

DIN 6914

ISO 14399-4

High-strength hexagon head bolts with large widths across flats for structural steel bolting

DIN 6916

Round washers for high-strength structural steel bolting

DIN 6921

ISO 1665

Hexagon flange bolts

DIN 6922

ISO 1665

Hexagon flange bolts with reduced shank

DIN 6923

ISO 1661

Hexagon nuts with flange

DIN 6924

ISO 7040

Prevailing torque type hexagon nuts with non-metallic insert

DIN 6924

ISO 10512

Prevailing torque type hexagon nuts with non-metallic insert

DIN 6925

ISO 7042

Prevailing torque type all-metal hexagon nuts

DIN 6925

ISO 10513

Prevailing torque type all-metal hexagon nuts

DIN 6926

ISO 7043

Prevailing torque type hexagon nuts with flange and with non-metallic insert

DIN 6926

ISO 12125

Prevailing torque type hexagon nuts with flange and with non-metallic insert

DIN 6927

ISO 7044

Prevailing torque type all-metal nuts with flange

DIN 6927

ISO 12126

Prevailing torque type all-metal nuts with flange

DIN 7045

Pan head screws with type H or type Z cross recess - product grade A

DIN 7337

ISO 14589

Break mandrel blind rivets

DIN 7337

ISO 15977 to ISO 15984

Break mandrel blind rivets

DIN 7337

ISO 16582 to ISO 16584

Break mandrel blind rivets

DIN 7343

ISO 8750

Spiral Pins; Normal Type

DIN 7344

ISO 8748

Spiral Pins; Heavy Duty Type

DIN 7346

ISO 13337

Spring-Type Straight Pins; (Roll Pins) Light-weight Type

DIN 7349

Plain Washers for Bolts with Heavy Clamping Sleeves

DIN 7500-1

ISO 7085

Thread rolling screws for metric ISO thread - Part 1: Types, designation, requirements

DIN 7500-2

Thread rolling screws for ISO metric thread; guideline values for hole diameters

DIN 7504

Self-drilling screws with tapping screw thread - Dimensions, requirements and testing

DIN 7513

Hexagon head and slotted head thread cutting screws - Dimensions, requirements and testing

DIN 7516

Cross recessed head thread cutting screws - Dimensions, requirements and testing

DIN 7603

Ring seals and gaskets

DIN 7970

ISO 1478

Threads and thread ends for tapping screws (modified version of ISO 1478)

DIN 7971

ISO 1481

BS4174

Slotted pan head tapping screws

DIN 7972

ISO 1482

Slotted countersunk head tapping screws

DIN 7973

ISO 1483

Slotted raised countersunk head tapping screws

DIN 7977

ISO 8737

Taper Pins with Thread Ends and Constant Point Lengths

DIN 7978

ISO 8736

Taper Pins with Internal Thread

DIN 7979

ISO 8733

Parallel Pins with Internal Thread

DIN 7979

ISO 8735

Parallel Pins with Internal Thread

DIN 7980

BS4464A

Spring lock washers with square ends for cheese head screws

DIN 7981

ISO 7049

Cross recessed pan head tapping screws

DIN 7982

ISO 7050

Cross recessed countersunk head tapping screws

DIN 7983

ISO 7051

Countersunk (Flat) Head Tapping Screws with Cross Recess

DIN 7984

Hexagon socket thin head cap screws

DIN 7985

ISO 7045

BS4183

Cross recessed raised Phillips Pan head screws

DIN 7989-1

Washers for steel structures - Product grade C

DIN 7989-2

Washers for steel structures - Product grade A

DIN 7991

ISO 10642

BS4168

Hexagon socket countersunk head cap screws

DIN 84

ISO 1207

BS4183

Product grade A slotted cheese head screws

DIN 85

ISO 1580

BS4183

Product grade A slotted pan head screws

DIN 9021

ISO 7093

Plain washers with large outside diameter

DIN 908

Hexagon socket screw plugs with parallel screw thread

DIN 910

Hexagon-duty hexagon head screw plugs

DIN 911

ISO 2936

Hexagon Socket Screw Keys

DIN 912

ISO 4762

BS4168

Hexagon socket head cap screws (modified version of ISO 4762)

DIN 912

ISO 21268

BS4168

Hexagon socket head cap screws (modified version of ISO 4762)

DIN 913

ISO 4026

Hexagon socket set screws with flat point (ISO 4026 modified)

DIN 914

ISO 4027

Hexagon socket set screws with cone point (ISO 4029 modified)

DIN 915

ISO 4028

Hexagon socket set screws with full dog point

DIN 916

ISO 4029

Hexagon socket set screws with cup point (ISO 4029 modified)

DIN 918-3

Overview of European Standards for fasteners

DIN 921

Slotted pan head screws with large head

DIN 923

Slotted pan head screws with shoulder

DIN 929

Hexagon weld nuts

DIN 93

Tab washers with long tab

DIN 930

Fine thread pitch partially threaded screws

DIN 931-1

ISO 4014

BS3692

M1,6 to M39 Hexagon Cap Screws Partially Threaded - Product grades A and B

DIN 931-2

ISO 4014

BS3692

M42 to M160x6 Hexagon Cap Screws Partially Threaded - Product grade B

DIN 933

ISO 4017

BS3692

M1,6 to M52 Hexagon Cap Screws Fully Threaded - Product grades 8.8

DIN 934

ISO 4032

Hexagon nuts with metric coarse and fine pitch thread - Product classes A and B

DIN 934

ISO 8673

Hexagon nuts with metric coarse and fine pitch thread - Product classes A and B

DIN 935-1

Hexagon slotted nuts and castle nuts with metric coarse and fine pitch thread - Product grades A and B

DIN 935-2

M42 to M160x6 hexagon head bolts; product grade B

DIN 935-3

Hexagon slotted nuts with metric coarse pitch thread - Product grade C

DIN 936

BS3692

M8 to M52 and M8x1 to M52x3 hexagon thin nuts; product grades A and B

DIN 937

Hexagon thin castle nuts

DIN 938

Studs with a length of engagement equal to about 1 d

DIN 939

Studs with a length of engagement equal to about 1,25 d

DIN 94

ISO 1234

Split pins

DIN 95

Slotted Raised Countersunk (Oval) Head Wood Screws

DIN 96

Slotted Round Head Wood Screws

DIN 960

ISO 8765

M8x1 to M100x4 hexagon head bolts with fine pitch thread - Product grades A and B

DIN 960

ISO 8676

M8x1 to M100x4 hexagon head bolts with fine pitch thread - Product grades A and B

DIN 961

ISO 8676

M8x1 to M52x3 hexagon head bolts with fine pitch thread - Product grades A and B

DIN 962

Designation system for fasteners

DIN 963

ISO 2009

BS3692

Slotted countersunk head screws (with countersunk heads as specified in ISO 2009-1972)

DIN 964

ISO 2010

BS3692

Slotted raised countersunk oval head screws

DIN 965

ISO 7046

BS3692

Cross recessed countersunk flat head screws

DIN 966

ISO 7047

Cross recessed raised countersunk head screws

DIN 970

ISO 4032

Hexagon nuts; Style 1; Metric coarse thread, Product grades A and B; ISO 4032 modified

DIN 971-1

ISO 8673

Style 1 hexagon nuts with metric fine pitch thread; property classes 6 and 8

DIN 971-2

ISO 8674

Style 2 hexagon nuts with metric fine pitch thread; property classes 10 and 12

DIN 972

ISO 4034

M5 to M39 hexagon nuts; style 1; product grade C (modified version of ISO 4034)

DIN 975

Threaded rods

DIN 976-1

Metric thread stud bolts

DIN 976-2

Metric interference-fit thread stud bolts

DIN 977

ISO 21670

Hexagon weld nuts with flange

DIN 979

Hexagon thin slotted nuts and castle nuts with metric coarse and fine pitch thread - Product grades A and B

DIN 980

ISO 7042

All-metal prevailing torque type hexagon nuts

DIN 980

ISO 10513

All-metal prevailing torque type hexagon nuts

DIN 981

Locknuts for use with rolling bearings

DIN 982

ISO 7040

Prevailing torque type hexagon nuts with non-metallic insert

DIN 982

ISO 10512

Prevailing torque type hexagon nuts with non-metallic insert

DIN 983

Retaining rings with lugs for use on shafts (external circlips)

DIN 985

ISO 10511

Prevailing torque type hexagon thin nuts with non-metallic insert

DIN 986

Prevailing torque type hexagon domed cap nuts with non-metallic insert

DIN 988

Shim rings and supporting rings

Note: this is a rough guide and you should always carry out your own trials to ensure you have the right fastener for your application.

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