This chart provided by Lyle Rawlins (lrawlins@deltanet.com)

Grit Size Comparison Chart

U.S. Graded (CAMI)
European Graded (FEPA)
Microns
Avg Dia
Mesh
Symbol
Mesh
Avg Dia
Microns
0.3
0.0000118
­
­
­
­
­ 
0.5
0.0000197
­
­
­
­
­ 
1.0
0.0000394
­
­
­
­
­ 
2.0
0.0000787
­
­
­
­
­ 
3.0
0.000118
­
­
­
­
­ 
4.0
0.000158
­
­
­
­
­ 
5.0
0.000197
­
­
­
­
­ 
6.0
0.000236
­
­
­
­
­ 
6.5
0.00026
1200
­
­
­ 
-
9.0
0.00035
­
­
­
­
­ 
9.2
0.00036
1000
­
­
­ 
-
12.0
0.00047
­
­
­
­
­ 
12.2
0.00048
800
­
­
­
­ 
15.0
0.00059
­
­
­
­
­ 
16.0
0.00062
600
­
P1200
0.00060
15.3 
19.7
0.00077
500
­
P1000
0.00071
18.3 
20.0
0.00079
­
­
­
­
­ 
23.6
0.00092
400
10/0
P800
0.00085
21.8 
25.0
0.00098
­
­
­
­
­ 
28.8
0.00112
360
­
P600
0.00100
25.8 
30.0
0.00118
­
 ­
­
­
­ 
 -
­
­
-
P500
0.00118
30.2 
36.0
0.00140
320
9/0
P400
0.00137
35.0 
40.0
0.001575
­
­
­
­
-
 -
­
­
-
P360
0.00158
40.5 
44.0
0.00172
280
8/0
­
­
­ 
45.0
0.00177
­
­
P320
0.00180
46.2 
50.0
0.00197
­
­
­
­
­ 
53.5
0.00209
240
7/0
P280
0.00204
52.5 
55.0
0.00217
­
­
­
­
­ 
66.0
0.00257
220
6/0
P220
0.00254
65.0 
78.0
0.00304
180
5/0
P180
0.00304
78.0 
93.0
0.00363
150
4/0
P150
0.00378
97.0 
116.0
0.00452
120
3/0
P120
0.00495
127.0 
141.0
0.0055
100
2/0
P100
0.00608
156.0 
192.0
0.00749
80
0
P80
0.00768
197.0 
268.0
0.01045
60
1/2
P60
0.01014
260.0 
351.0
0.0139
50
1
P50
0.01271
326.0 
428.0
0.0169
40
1-1/2
P40
0.01601
412.0 
535.0
0.02087
36
2
P36
0.02044
524.0 
638.0
0.02488
30
2-1/2
P30
0.02426
622.0 
715.0
0.02789
24
3
P24
0.02886
740.0 
905.0
0.03535
20
3-1/2
P20
0.03838
984.0 
1320.0
0.05148
16
4
P16
0.05164
1324.0 
1842.0
0.07174
12
4-1/2
P12
0.06880
1764.0

Note: This chart only compares CAMI vs. FEPA grit sizes for coated abrasives, and is based on information from CAMI, FEPA &;CAFA (Coated Abrasive Fabricators Association).

Yes, there are other standards but in 20+ years of selling both bonded and coated abrasives I have not seen any definition of them.