Back-up Ring Size Chart

The chart gives the metric and inch dimensions for the most common AS568 sizes of backup rings.
 

NOTE: The “A” dimension, or Axial Height, applies only to the rubber contoured backup rings. PTFE backup rings are flat, so do not have this contour.
 

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Backup Ring Size Chart

Dash Number
I.D. inch
Width inch
Thickness inch
A inch
I.D. mm
Width mm
Thickness mm
A mm
4
0.096
0.053
0.049
0.045
2.44
1.35
1.24
1.14
5
0.127
0.053
0.049
0.045
3.23
1.35
1.24
1.14
6
0.14
0.053
0.049
0.045
3.56
1.35
1.24
1.14
7
0.171
0.053
0.049
0.045
4.34
1.35
1.24
1.14
8
0.202
0.053
0.049
0.045
5.13
1.35
1.24
1.14
9
0.234
0.053
0.049
0.045
5.94
1.35
1.24
1.14
10
0.265
0.053
0.049
0.045
6.73
1.35
1.24
1.14
11
0.327
0.053
0.049
0.045
8.31
1.35
1.24
1.14
12
0.39
0.053
0.049
0.045
9.91
1.35
1.24
1.14
13
0.455
0.053
0.049
0.045
11.56
1.35
1.24
1.14
14
0.518
0.053
0.049
0.045
13.16
1.35
1.24
1.14
15
0.58
0.053
0.049
0.045
14.73
1.35
1.24
1.14
16
0.643
0.053
0.049
0.045
16.33
1.35
1.24
1.14
17
0.705
0.053
0.049
0.045
17.91
1.35
1.24
1.14
18
0.768
0.053
0.049
0.045
19.51
1.35
1.24
1.14
19
0.83
0.053
0.049
0.045
21.08
1.35
1.24
1.14
20
0.893
0.053
0.049
0.045
22.68
1.35
1.24
1.14
21
0.955
0.053
0.049
0.045
24.26
1.35
1.24
1.14
22
1.018
0.053
0.049
0.045
25.86
1.35
1.24
1.14
23
1.08
0.053
0.049
0.045
27.43
1.35
1.24
1.14
24
1.143
0.053
0.049
0.045
29.03
1.35
1.24
1.14
25
1.205
0.053
0.049
0.045
30.61
1.35
1.24
1.14
26
1.268
0.053
0.049
0.045
32.21
1.35
1.24
1.14
27
1.33
0.053
0.049
0.045
33.78
1.35
1.24
1.14
28
1.393
0.053
0.049
0.045
35.38
1.35
1.24
1.14
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