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Cable Size Chart

 The Gauge Guide bullets will help you determine the overall size (including insulation) of an unmarked cable. 

Actual diameters may vary depending on the age, make and insulation thickness of your cable.

Check out our Printable Version PDF to more accurately measure the end of your cable against Gauge Guide bullets.

 

 

If you are still not sure the most accurate way to measure your cable is to determine the area in mm2 of the copper conductors.

As an example, let's assume we want to know the area for 3mm auto cable:

  • Count the total number of strands. (14)
  • Measure the diameter of one of the strands. (0.32)

In this case we have 14 strands @ 0.32mm each. Knowing this we now do the following calculations:

  • Square (multiply by itself) the diameter of each strand (0.32 × 0.32 = 0.1024)
  • Multiply this result  x (Pi) 3.14  (0.1024 x 3.14 = 0.321536)
  • Divide this result by 4 (0.321536/4 = 0.080384)
  • Multiply this result by the number of strands (0.080384 x 14)

Therefore the approximate area for 3mm auto cable is:

  • 1.13mm2

 

Single Core Automotive

Auto Size 

Nom Area mm2

Nom O.D.mm

Amp Rating

Part # Prefix

Gauge Guide

3mm

1.13

2.2

20

C16

4mm

1.84

2.6

28

C14

5mm

2.90

3.0

37

C12

6mm

4.59

4.0

48

C10



 
Thin Wall Single Core Automotive

Auto Size

Nom Area mm2

Nom O.D.mm

Amp Rating

Part # Prefix

Gauge Guide

2mm

0.5

1.5

10

C18TW

3mm

1.0

2.0

15

C16TW

4mm

2.0

2.55

20

C14TW



 
Double Insulated (Gas) Automotive

Auto Size

Nom Area mm2

Nom O.D.mm

Amp Rating

Part # Prefix

Gauge Guide

3mm

1.13

3.8

20

C16DI

4mm

1.84

4.2

28

C14DI

5mm

2.90

4.9

37

C12DI

6mm

4.59

5.7

48

C10DI



 
High Tension Automotive

Auto Size

Nom Area mm2

Nom O.D.mm

Amp Rating

Part # Prefix

Gauge Guide

3mm

1.13

7.0

20

C7HT



 
Figure 8

Auto Size

Nom Area mm2

Nom O.D.mm

Amp Rating

Part # Prefix

Gauge Guide

2 x 2mm

0.44

2.4 x 4.8

2.5

C20T

2 x 2.5mm

0.75

2.6 x 5.1

5

C18T

2 x 3mm

1.13

2.6 x 5.9

10

C16T

2 x 4mm

1.84

3.1 x 6.7

15

C14T



 
Twin Sheath Automotive

Auto Size

Nom Area mm2

Nom O.D.mm

Amp Rating

Part # Prefix

Gauge Guide

2 x 2mm

0.56

3.1 x 5.1

8

C2/18

2 x 3mm

1.13

3.3 x 5.5

16

C2/16

2 x 4mm

1.84

3.8 x 6.3

22

C2/14

2 x 5mm

2.90

4.5 x 7.4

29

C2/12

2 x 6mm

4.59

5.7 x 9.6

38

C2/10

2 x 8 B&S

7.71

7.1 x 12.5

59

C2/8

2 x 6 B&S

13.5

8.8 x 16

82

C2/6

2 x 2 B&S

32.07

13.4 x 24.6

150

C2/2



 
Multi-Core Sheathed Automotive

Auto Size

Nom Area mm2

Nom O.D.mm

Amp Rating

Part # Prefix

Gauge Guide

3 x 3mm

1.13

5.7

14

C3/16

3 x 4mm

0.92

6.7

12

C4/16

5 x 2mm

0.56

6.0

7

C5/18

5 x 3mm

1.13

4.0

11

C5/16

5 x 4mm

1.84

8.2

15

C5/14

7 x 2mm

0.56

6.7

5

C7/18

7 x 3mm

1.13

7.7

10

C7/16

7 x 4mm

1.84

8.9

14

C7/14

2 x 6mm

1 x 5mm

1 x 3mm

4.59

2.90

1.13

10

38

37

20

C4/6653



 
Security/Data

Auto Size

Nom Area mm2

Nom O.D.mm

Amp Rating

Part # Prefix

Gauge Guide

-

0.44

6.3

3

C SEC.14208

-

0.75

6.8

6

C2SC24/.2

-

0.50

5.8

3

C2SC7/.3-100

-

0.44

4.8

3

C4/SEC.5/100



 
 
Battery Automotive

Auto Size

Nom Area mm2

Nom O.D.mm

Amp Rating

Part # Prefix

Gauge Guide

8 B&S

7.71

5.5

74

C8

6 B&S

13.5

7.2

103

C6

4 B&S

20.26

8.3

135

C4

3 B&S

26.45

10.2

168

C3

2 B&S

32.07

11.3

188

C2

1 B&S

39.55

12.1

210

C1

0 B&S

49.00

12.7

246

C0

00 B&S

64.15

14.5

292

C00

000 B&S

83.19

16.4

335

C000



 
Silicone (150°C)

Auto Size

Nom Area mm2

Nom O.D.mm

Amp Rating

Part # Prefix

Gauge Guide

-

1.0

2.8

10

C32/.2

-

1.5

3.3

15

C30/.25