CIDR määräytyy rfc1878 standardin mukaisesti.

Subnetmask
CIDR
128.0.0.0
1
192.0.0.0
2
224.0.0.0
3
240.0.0.0
4
248.0.0.0
5
252.0.0.0
6
254.0.0.0
7
255.0.0.0
8
255.128.0.0
9
255.192.0.0
10
255.224.0.0
11
255.240.0.0
12
255.248.0.0
13
255.252.0.0
14
255.254.0.0
15
255.255.0.0
16
255.255.128.0
17
255.255.192.0
18
255.255.224.0
19
255.255.240.0
20
255.255.248.0
21
255.255.252.0
22
255.255.254.0
23
255.255.255.0
24
255.255.255.128
25
255.255.255.192
26
255.255.255.224
27
255.255.255.240
28
255.255.255.248
29
255.255.255.252
30
255.255.255.254
31
255.255.255.255
32