SAE-Metric Wrenches

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Wrench Conversion -
Size Equivalence Chart

This wrench size conversion chart converts metric-sized wrenches to standard-sized wrenches, and shows which wrenches are roughly interchangeable.

Metric wrench sizes are shown, along with their "English Standard" equivalence, in 1/1000s of an inch. "Standard-size" wrenches refers to SAE sizes - the Society of Automotive Engineers.

Wrench Conversion Table - Equivalent Sizes
Difference in 1/1000s of an inch
Size in Inches
Standard
SAE
Wrench Size (inches)
Metric Wrench Size (mm)

Notes - compares Standard and Metric wrench sizes(where they MATCH, and where they don't - wrench equivalence)

1

0.156
5/32

 

Close enough (5/32 and 4mm)

30
0.157

 

4
9
0.188
3/16

 

22
0.197

 

5

 1"= 2.54cm (= 0.254m)

17
0.219
7/32

 

1mm= 0.03937"

14
0.236

 

6

1cm= 0.3937"

26
0.250
1/4

 

 

6
0.276

 

7

 

31
0.281
9/32

 

 

2

0.313
5/16

 

Close enough (5/16 and 8mm)

29
0.315

 

8
11
0.344
11/32

 

 

21
0.354

 

9

 

19
0.375
3/8

 

 

13
0.394

 

10

 

27
0.406
13/32

 

 

4

0.433

11

Close enough (7/16 and 11mm)

31
0.438
7/16

 

4

0.469
15/32

 

Close enough (15/32 and 12mm)

28
0.472

 

12
12
0.500
1/2

 

 

19
0.512

 

13

 

20
0.531
17/32

 

 

11
0.551

 

14

 

28
0.563
9/16

 

 

3

0.591

 

15

Close enough (19/32 and 15mm)

31
0.594
19/32

 Bicycle

5
0.625
5/8

 

?

26
0.630

 Bicycle

16

13
0.656
21/32

 

 

18
0.669

 

17

 

21
0.688
11/16

 

 

10
0.709

 

18

 

29
0.719
23/32

 

 

2

0.748

 

19

Close enough (3/4 and 19mm)

31
0.750
3/4

 

6
0.781
25/32

 

 

25
0.787

 

20

 

14
0.813
13/16

 

 

17
0.827

 

21

 

22
0.844
27/32

 

 

9
0.866

 

22

 

31
0.875
7/8

 

 

1

0.9055

 

23

Close enough (29/32 and 23mm)

31
0.9063
29/32

 

7
0.938
15/16

 

 

55
0.945

 

24

 

 

1.000
1

 

 

NOMENCLATURE

English to Metric

1 inch =

 

2.54 centimeters (= 0.254m)

Metric to English

1 centimeter =

 

0.3937 inches

DISCLAIMER
Although the author has tried to be as accurate as possible, errors are possible.

I could not find an online table like the above. So, I made this conversion chart, to help myself understand the relationships between wrench sizes of the metric system and wrench sizes of the standard system. I hope that it helps you.


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Vaughn's Summaries (One-Pagers)
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This Vaughns 1-Pagers Wrench Size Conversion/ Size Equivalence Chart web page was updated on 2008-10-29.