Thread: Metric to SAE Conversion

I just got into a garage with no metric tools, thought I would post up a table that helps me navigate my way around SAE. Remember, bolt size is first number, standard wrench is 2nd, and metric is 3rd.

STANDARD / METRIC
WRENCH CONVERSION CHART

Bolt Size
Standard
Metric

1/8"
5/16
8 mm

3/16"
3/8
10 mm

1/4"
7/16
11 mm

5/16"
1/2
13 mm

3/8"
9/16
14 mm

7/16"
5/8
16 mm

1/2"
3/4
19 mm

9/16"
13/16
21 mm

5/8"
15/16
24 mm

3/4"
1 1/8
28 mm

Pretty much none of those are a real tight fit. So you will strip bolt heads.
For example 1/2 = 12,7mm, a 13mm socket will badly strip the head.

If you are working on metric fasteners with SAE wrenches, the bolt sizes you list are irrelevant. Be very careful if you are using worn 12 point SAE wrenches on worn or rusty metric bolt heads and nuts. Use 6 points if you have them.