Wright Safety Fit Table
MADE IN USA
Make Sure to Use the Right Drive
Wrench
Min. Best Wrench
Min. Best Wrench
Min. Best Wrench
Min. Best
Size
Opening Drive
Size
Opening Drive
Size
Opening Drive
Size
Opening Drive
inch metric
mm inches inch metric
mm inches inch metric
mm inches inch metric
mm inches
4.0 1/4
4.8 1/4
5.0 1/4
5.5 1/4
6.0 1/4
6.3 1/4
7.0 1/4
7.1 1/4
7.9 1/4
8.0 1/4
8.7 1/4
9.0 1/4
9.5 1/4
10.0 1/4
11.0 3/8
11.1 3/8
12.0 3/8
12.7 3/8
13.0 3/8
14.0 3/8
14.3
15.0
15.1
15.9
16.0
16.7
17.0
11/16
18mm
19mm
3/4
25/32
20mm
13/16
21mm
22mm
7/8
23mm
29/32
15/16
24mm
31/32
25mm
1
26mm
1-1/16
27mm
28mm
1-1/8
29mm
30mm
1-3/16
31mm
1-1/4
17.5
18.0
19.0
19.1
19.8
20.0
20.6 1/2
21.0 1/2
22.0 1/2
22.2 1/2
23.0 1/2
23.0 1/2
23.8 1/2
24.0 1/2
24.6 1/2
25.0 1/2
25.4 1/2
26.0
27.0
27.0
28.0
28.6 3/4
29.0 3/4
30.0 3/4
30.2 3/4
31.0 3/4
31.8 3/4
Use this table to select the correct size wrench for any size fastener–inch
or metric.
1. Measure the fastener head or nut with metric calipers.
2. Look down the MINIMUM OPENING column and find the first number
larger than your reading.
3. Look to the left of that number to find the wrench size. (The vertical
line between two sizes indicates that the range of an inch wrench
overlaps that of a metric wrench. Either size can often be used.)
This table is to help you select the correct size wrench for any fastener,
even if you do not know whether it is an inch or a metric fastener. The
closer a wrench fits a fastener, the more torque can be transmitted without
rounding the fastener corners or causing excessive wear to the wrench.
First, measure the fastener head or nut with calipers in millimeters. Then,
look down the MINIMUM OPENING column to find the first number larger
than your reading. For example, if you read 15.1, look down the table
until you come to the value 15.9; then look across the table to 5/8". The
vertical line between two sizes indicates that the range of an inch wrench
overlaps that of a metric wrench. Either size can often be used.
However, the table can also be used to find the best possible fit. A 16mm
wrench could be used, but 5/8" provides a better fit in this example. If
you read 31.8, you may either use the table or recognize that this is very
close to, but slightly smaller than 32mm. Therefore, you can safely use a
32mm wrench without referring to the table.
32mm
33mm
1-5/16
34mm
1-3/8
35mm
36mm
1-7/16
38mm
1-1/2
1-9/16
41mm
1-5/8
42mm
1-11/16
43mm
1-3/4
46mm
1-13/16
1-7/8
1-15/16
50mm
2
52mm
2-1/16
2-1/8
54mm
32.0 3/4
33.0 3/4
33.3 3/4
34.0 3/4
34.9 3/4
35.0
36.0
36.5
38.0
38.1 1
39.7 1
41.0