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IP subnet calculator

Type an address with its prefix or mask to see the network, its usable range and masks. Split it into smaller subnets, or look up any prefix in the reference tables.

Network137.32.0.0/12
Usable hosts1,048,574
Subnet mask255.240.0.0
Addresses1,048,576
Network address
137.32.0.0
Broadcast address
137.47.255.255
First usable
137.32.0.1
Last usable
137.47.255.254
Usable hosts
1,048,574 (1,048,576 less the network and broadcast addresses)
Subnet mask
255.240.0.0
Wildcard mask
0.15.255.255 (Cisco ACLs, OSPF)
Prefix length
/12
Type
Public public
Old class
B (default /16)
As numbers
Hex 89200000 · Integer 2300575744 to 2301624319
Reverse DNS zones
32.137.in-addr.arpa
33.137.in-addr.arpa
34.137.in-addr.arpa
35.137.in-addr.arpa
36.137.in-addr.arpa
37.137.in-addr.arpa
38.137.in-addr.arpa
39.137.in-addr.arpa
40.137.in-addr.arpa
41.137.in-addr.arpa
42.137.in-addr.arpa
43.137.in-addr.arpa
44.137.in-addr.arpa
45.137.in-addr.arpa
46.137.in-addr.arpa
47.137.in-addr.arpa
/12 is not on a 8-bit boundary, so it takes 16 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10001001.00100000.00000000.00000000137.32.0.0
Subnet mask11111111.11110000.00000000.00000000255.240.0.0
Network10001001.00100000.00000000.00000000137.32.0.0
Broadcast10001001.00101111.11111111.11111111137.47.255.255
Split into smaller subnets/20
/13 (2)/14 (4)/15 (8)/16 (16)/17 (32)/18 (64)/19 (128)/20 (256)/21 (512)/22 (1,024)/23 (2,048)/24 (4,096)

137.32.0.0/12 makes 256 subnets of /20.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1137.32.0.0/20137.32.0.1 to 137.32.15.254137.32.15.2554,094
2137.32.16.0/20137.32.16.1 to 137.32.31.254137.32.31.2554,094
3137.32.32.0/20137.32.32.1 to 137.32.47.254137.32.47.2554,094
4137.32.48.0/20137.32.48.1 to 137.32.63.254137.32.63.2554,094
5137.32.64.0/20137.32.64.1 to 137.32.79.254137.32.79.2554,094
6137.32.80.0/20137.32.80.1 to 137.32.95.254137.32.95.2554,094
7137.32.96.0/20137.32.96.1 to 137.32.111.254137.32.111.2554,094
8137.32.112.0/20137.32.112.1 to 137.32.127.254137.32.127.2554,094
9137.32.128.0/20137.32.128.1 to 137.32.143.254137.32.143.2554,094
10137.32.144.0/20137.32.144.1 to 137.32.159.254137.32.159.2554,094
11137.32.160.0/20137.32.160.1 to 137.32.175.254137.32.175.2554,094
12137.32.176.0/20137.32.176.1 to 137.32.191.254137.32.191.2554,094
13137.32.192.0/20137.32.192.1 to 137.32.207.254137.32.207.2554,094
14137.32.208.0/20137.32.208.1 to 137.32.223.254137.32.223.2554,094
15137.32.224.0/20137.32.224.1 to 137.32.239.254137.32.239.2554,094
16137.32.240.0/20137.32.240.1 to 137.32.255.254137.32.255.2554,094
17137.33.0.0/20137.33.0.1 to 137.33.15.254137.33.15.2554,094
18137.33.16.0/20137.33.16.1 to 137.33.31.254137.33.31.2554,094
19137.33.32.0/20137.33.32.1 to 137.33.47.254137.33.47.2554,094
20137.33.48.0/20137.33.48.1 to 137.33.63.254137.33.63.2554,094
21137.33.64.0/20137.33.64.1 to 137.33.79.254137.33.79.2554,094
22137.33.80.0/20137.33.80.1 to 137.33.95.254137.33.95.2554,094
23137.33.96.0/20137.33.96.1 to 137.33.111.254137.33.111.2554,094
24137.33.112.0/20137.33.112.1 to 137.33.127.254137.33.127.2554,094
25137.33.128.0/20137.33.128.1 to 137.33.143.254137.33.143.2554,094
26137.33.144.0/20137.33.144.1 to 137.33.159.254137.33.159.2554,094
27137.33.160.0/20137.33.160.1 to 137.33.175.254137.33.175.2554,094
28137.33.176.0/20137.33.176.1 to 137.33.191.254137.33.191.2554,094
29137.33.192.0/20137.33.192.1 to 137.33.207.254137.33.207.2554,094
30137.33.208.0/20137.33.208.1 to 137.33.223.254137.33.223.2554,094
31137.33.224.0/20137.33.224.1 to 137.33.239.254137.33.239.2554,094
32137.33.240.0/20137.33.240.1 to 137.33.255.254137.33.255.2554,094
33137.34.0.0/20137.34.0.1 to 137.34.15.254137.34.15.2554,094
34137.34.16.0/20137.34.16.1 to 137.34.31.254137.34.31.2554,094
35137.34.32.0/20137.34.32.1 to 137.34.47.254137.34.47.2554,094
36137.34.48.0/20137.34.48.1 to 137.34.63.254137.34.63.2554,094
37137.34.64.0/20137.34.64.1 to 137.34.79.254137.34.79.2554,094
38137.34.80.0/20137.34.80.1 to 137.34.95.254137.34.95.2554,094
39137.34.96.0/20137.34.96.1 to 137.34.111.254137.34.111.2554,094
40137.34.112.0/20137.34.112.1 to 137.34.127.254137.34.127.2554,094
41137.34.128.0/20137.34.128.1 to 137.34.143.254137.34.143.2554,094
42137.34.144.0/20137.34.144.1 to 137.34.159.254137.34.159.2554,094
43137.34.160.0/20137.34.160.1 to 137.34.175.254137.34.175.2554,094
44137.34.176.0/20137.34.176.1 to 137.34.191.254137.34.191.2554,094
45137.34.192.0/20137.34.192.1 to 137.34.207.254137.34.207.2554,094
46137.34.208.0/20137.34.208.1 to 137.34.223.254137.34.223.2554,094
47137.34.224.0/20137.34.224.1 to 137.34.239.254137.34.239.2554,094
48137.34.240.0/20137.34.240.1 to 137.34.255.254137.34.255.2554,094
49137.35.0.0/20137.35.0.1 to 137.35.15.254137.35.15.2554,094
50137.35.16.0/20137.35.16.1 to 137.35.31.254137.35.31.2554,094
51137.35.32.0/20137.35.32.1 to 137.35.47.254137.35.47.2554,094
52137.35.48.0/20137.35.48.1 to 137.35.63.254137.35.63.2554,094
53137.35.64.0/20137.35.64.1 to 137.35.79.254137.35.79.2554,094
54137.35.80.0/20137.35.80.1 to 137.35.95.254137.35.95.2554,094
55137.35.96.0/20137.35.96.1 to 137.35.111.254137.35.111.2554,094
56137.35.112.0/20137.35.112.1 to 137.35.127.254137.35.127.2554,094
57137.35.128.0/20137.35.128.1 to 137.35.143.254137.35.143.2554,094
58137.35.144.0/20137.35.144.1 to 137.35.159.254137.35.159.2554,094
59137.35.160.0/20137.35.160.1 to 137.35.175.254137.35.175.2554,094
60137.35.176.0/20137.35.176.1 to 137.35.191.254137.35.191.2554,094
61137.35.192.0/20137.35.192.1 to 137.35.207.254137.35.207.2554,094
62137.35.208.0/20137.35.208.1 to 137.35.223.254137.35.223.2554,094
63137.35.224.0/20137.35.224.1 to 137.35.239.254137.35.239.2554,094
64137.35.240.0/20137.35.240.1 to 137.35.255.254137.35.255.2554,094
65137.36.0.0/20137.36.0.1 to 137.36.15.254137.36.15.2554,094
66137.36.16.0/20137.36.16.1 to 137.36.31.254137.36.31.2554,094
67137.36.32.0/20137.36.32.1 to 137.36.47.254137.36.47.2554,094
68137.36.48.0/20137.36.48.1 to 137.36.63.254137.36.63.2554,094
69137.36.64.0/20137.36.64.1 to 137.36.79.254137.36.79.2554,094
70137.36.80.0/20137.36.80.1 to 137.36.95.254137.36.95.2554,094
71137.36.96.0/20137.36.96.1 to 137.36.111.254137.36.111.2554,094
72137.36.112.0/20137.36.112.1 to 137.36.127.254137.36.127.2554,094
73137.36.128.0/20137.36.128.1 to 137.36.143.254137.36.143.2554,094
74137.36.144.0/20137.36.144.1 to 137.36.159.254137.36.159.2554,094
75137.36.160.0/20137.36.160.1 to 137.36.175.254137.36.175.2554,094
76137.36.176.0/20137.36.176.1 to 137.36.191.254137.36.191.2554,094
77137.36.192.0/20137.36.192.1 to 137.36.207.254137.36.207.2554,094
78137.36.208.0/20137.36.208.1 to 137.36.223.254137.36.223.2554,094
79137.36.224.0/20137.36.224.1 to 137.36.239.254137.36.239.2554,094
80137.36.240.0/20137.36.240.1 to 137.36.255.254137.36.255.2554,094
81137.37.0.0/20137.37.0.1 to 137.37.15.254137.37.15.2554,094
82137.37.16.0/20137.37.16.1 to 137.37.31.254137.37.31.2554,094
83137.37.32.0/20137.37.32.1 to 137.37.47.254137.37.47.2554,094
84137.37.48.0/20137.37.48.1 to 137.37.63.254137.37.63.2554,094
85137.37.64.0/20137.37.64.1 to 137.37.79.254137.37.79.2554,094
86137.37.80.0/20137.37.80.1 to 137.37.95.254137.37.95.2554,094
87137.37.96.0/20137.37.96.1 to 137.37.111.254137.37.111.2554,094
88137.37.112.0/20137.37.112.1 to 137.37.127.254137.37.127.2554,094
89137.37.128.0/20137.37.128.1 to 137.37.143.254137.37.143.2554,094
90137.37.144.0/20137.37.144.1 to 137.37.159.254137.37.159.2554,094
91137.37.160.0/20137.37.160.1 to 137.37.175.254137.37.175.2554,094
92137.37.176.0/20137.37.176.1 to 137.37.191.254137.37.191.2554,094
93137.37.192.0/20137.37.192.1 to 137.37.207.254137.37.207.2554,094
94137.37.208.0/20137.37.208.1 to 137.37.223.254137.37.223.2554,094
95137.37.224.0/20137.37.224.1 to 137.37.239.254137.37.239.2554,094
96137.37.240.0/20137.37.240.1 to 137.37.255.254137.37.255.2554,094
97137.38.0.0/20137.38.0.1 to 137.38.15.254137.38.15.2554,094
98137.38.16.0/20137.38.16.1 to 137.38.31.254137.38.31.2554,094
99137.38.32.0/20137.38.32.1 to 137.38.47.254137.38.47.2554,094
100137.38.48.0/20137.38.48.1 to 137.38.63.254137.38.63.2554,094
101137.38.64.0/20137.38.64.1 to 137.38.79.254137.38.79.2554,094
102137.38.80.0/20137.38.80.1 to 137.38.95.254137.38.95.2554,094
103137.38.96.0/20137.38.96.1 to 137.38.111.254137.38.111.2554,094
104137.38.112.0/20137.38.112.1 to 137.38.127.254137.38.127.2554,094
105137.38.128.0/20137.38.128.1 to 137.38.143.254137.38.143.2554,094
106137.38.144.0/20137.38.144.1 to 137.38.159.254137.38.159.2554,094
107137.38.160.0/20137.38.160.1 to 137.38.175.254137.38.175.2554,094
108137.38.176.0/20137.38.176.1 to 137.38.191.254137.38.191.2554,094
109137.38.192.0/20137.38.192.1 to 137.38.207.254137.38.207.2554,094
110137.38.208.0/20137.38.208.1 to 137.38.223.254137.38.223.2554,094
111137.38.224.0/20137.38.224.1 to 137.38.239.254137.38.239.2554,094
112137.38.240.0/20137.38.240.1 to 137.38.255.254137.38.255.2554,094
113137.39.0.0/20137.39.0.1 to 137.39.15.254137.39.15.2554,094
114137.39.16.0/20137.39.16.1 to 137.39.31.254137.39.31.2554,094
115137.39.32.0/20137.39.32.1 to 137.39.47.254137.39.47.2554,094
116137.39.48.0/20137.39.48.1 to 137.39.63.254137.39.63.2554,094
117137.39.64.0/20137.39.64.1 to 137.39.79.254137.39.79.2554,094
118137.39.80.0/20137.39.80.1 to 137.39.95.254137.39.95.2554,094
119137.39.96.0/20137.39.96.1 to 137.39.111.254137.39.111.2554,094
120137.39.112.0/20137.39.112.1 to 137.39.127.254137.39.127.2554,094
121137.39.128.0/20137.39.128.1 to 137.39.143.254137.39.143.2554,094
122137.39.144.0/20137.39.144.1 to 137.39.159.254137.39.159.2554,094
123137.39.160.0/20137.39.160.1 to 137.39.175.254137.39.175.2554,094
124137.39.176.0/20137.39.176.1 to 137.39.191.254137.39.191.2554,094
125137.39.192.0/20137.39.192.1 to 137.39.207.254137.39.207.2554,094
126137.39.208.0/20137.39.208.1 to 137.39.223.254137.39.223.2554,094
127137.39.224.0/20137.39.224.1 to 137.39.239.254137.39.239.2554,094
128137.39.240.0/20137.39.240.1 to 137.39.255.254137.39.255.2554,094
129137.40.0.0/20137.40.0.1 to 137.40.15.254137.40.15.2554,094
130137.40.16.0/20137.40.16.1 to 137.40.31.254137.40.31.2554,094
131137.40.32.0/20137.40.32.1 to 137.40.47.254137.40.47.2554,094
132137.40.48.0/20137.40.48.1 to 137.40.63.254137.40.63.2554,094
133137.40.64.0/20137.40.64.1 to 137.40.79.254137.40.79.2554,094
134137.40.80.0/20137.40.80.1 to 137.40.95.254137.40.95.2554,094
135137.40.96.0/20137.40.96.1 to 137.40.111.254137.40.111.2554,094
136137.40.112.0/20137.40.112.1 to 137.40.127.254137.40.127.2554,094
137137.40.128.0/20137.40.128.1 to 137.40.143.254137.40.143.2554,094
138137.40.144.0/20137.40.144.1 to 137.40.159.254137.40.159.2554,094
139137.40.160.0/20137.40.160.1 to 137.40.175.254137.40.175.2554,094
140137.40.176.0/20137.40.176.1 to 137.40.191.254137.40.191.2554,094
141137.40.192.0/20137.40.192.1 to 137.40.207.254137.40.207.2554,094
142137.40.208.0/20137.40.208.1 to 137.40.223.254137.40.223.2554,094
143137.40.224.0/20137.40.224.1 to 137.40.239.254137.40.239.2554,094
144137.40.240.0/20137.40.240.1 to 137.40.255.254137.40.255.2554,094
145137.41.0.0/20137.41.0.1 to 137.41.15.254137.41.15.2554,094
146137.41.16.0/20137.41.16.1 to 137.41.31.254137.41.31.2554,094
147137.41.32.0/20137.41.32.1 to 137.41.47.254137.41.47.2554,094
148137.41.48.0/20137.41.48.1 to 137.41.63.254137.41.63.2554,094
149137.41.64.0/20137.41.64.1 to 137.41.79.254137.41.79.2554,094
150137.41.80.0/20137.41.80.1 to 137.41.95.254137.41.95.2554,094
151137.41.96.0/20137.41.96.1 to 137.41.111.254137.41.111.2554,094
152137.41.112.0/20137.41.112.1 to 137.41.127.254137.41.127.2554,094
153137.41.128.0/20137.41.128.1 to 137.41.143.254137.41.143.2554,094
154137.41.144.0/20137.41.144.1 to 137.41.159.254137.41.159.2554,094
155137.41.160.0/20137.41.160.1 to 137.41.175.254137.41.175.2554,094
156137.41.176.0/20137.41.176.1 to 137.41.191.254137.41.191.2554,094
157137.41.192.0/20137.41.192.1 to 137.41.207.254137.41.207.2554,094
158137.41.208.0/20137.41.208.1 to 137.41.223.254137.41.223.2554,094
159137.41.224.0/20137.41.224.1 to 137.41.239.254137.41.239.2554,094
160137.41.240.0/20137.41.240.1 to 137.41.255.254137.41.255.2554,094
161137.42.0.0/20137.42.0.1 to 137.42.15.254137.42.15.2554,094
162137.42.16.0/20137.42.16.1 to 137.42.31.254137.42.31.2554,094
163137.42.32.0/20137.42.32.1 to 137.42.47.254137.42.47.2554,094
164137.42.48.0/20137.42.48.1 to 137.42.63.254137.42.63.2554,094
165137.42.64.0/20137.42.64.1 to 137.42.79.254137.42.79.2554,094
166137.42.80.0/20137.42.80.1 to 137.42.95.254137.42.95.2554,094
167137.42.96.0/20137.42.96.1 to 137.42.111.254137.42.111.2554,094
168137.42.112.0/20137.42.112.1 to 137.42.127.254137.42.127.2554,094
169137.42.128.0/20137.42.128.1 to 137.42.143.254137.42.143.2554,094
170137.42.144.0/20137.42.144.1 to 137.42.159.254137.42.159.2554,094
171137.42.160.0/20137.42.160.1 to 137.42.175.254137.42.175.2554,094
172137.42.176.0/20137.42.176.1 to 137.42.191.254137.42.191.2554,094
173137.42.192.0/20137.42.192.1 to 137.42.207.254137.42.207.2554,094
174137.42.208.0/20137.42.208.1 to 137.42.223.254137.42.223.2554,094
175137.42.224.0/20137.42.224.1 to 137.42.239.254137.42.239.2554,094
176137.42.240.0/20137.42.240.1 to 137.42.255.254137.42.255.2554,094
177137.43.0.0/20137.43.0.1 to 137.43.15.254137.43.15.2554,094
178137.43.16.0/20137.43.16.1 to 137.43.31.254137.43.31.2554,094
179137.43.32.0/20137.43.32.1 to 137.43.47.254137.43.47.2554,094
180137.43.48.0/20137.43.48.1 to 137.43.63.254137.43.63.2554,094
181137.43.64.0/20137.43.64.1 to 137.43.79.254137.43.79.2554,094
182137.43.80.0/20137.43.80.1 to 137.43.95.254137.43.95.2554,094
183137.43.96.0/20137.43.96.1 to 137.43.111.254137.43.111.2554,094
184137.43.112.0/20137.43.112.1 to 137.43.127.254137.43.127.2554,094
185137.43.128.0/20137.43.128.1 to 137.43.143.254137.43.143.2554,094
186137.43.144.0/20137.43.144.1 to 137.43.159.254137.43.159.2554,094
187137.43.160.0/20137.43.160.1 to 137.43.175.254137.43.175.2554,094
188137.43.176.0/20137.43.176.1 to 137.43.191.254137.43.191.2554,094
189137.43.192.0/20137.43.192.1 to 137.43.207.254137.43.207.2554,094
190137.43.208.0/20137.43.208.1 to 137.43.223.254137.43.223.2554,094
191137.43.224.0/20137.43.224.1 to 137.43.239.254137.43.239.2554,094
192137.43.240.0/20137.43.240.1 to 137.43.255.254137.43.255.2554,094
193137.44.0.0/20137.44.0.1 to 137.44.15.254137.44.15.2554,094
194137.44.16.0/20137.44.16.1 to 137.44.31.254137.44.31.2554,094
195137.44.32.0/20137.44.32.1 to 137.44.47.254137.44.47.2554,094
196137.44.48.0/20137.44.48.1 to 137.44.63.254137.44.63.2554,094
197137.44.64.0/20137.44.64.1 to 137.44.79.254137.44.79.2554,094
198137.44.80.0/20137.44.80.1 to 137.44.95.254137.44.95.2554,094
199137.44.96.0/20137.44.96.1 to 137.44.111.254137.44.111.2554,094
200137.44.112.0/20137.44.112.1 to 137.44.127.254137.44.127.2554,094
201137.44.128.0/20137.44.128.1 to 137.44.143.254137.44.143.2554,094
202137.44.144.0/20137.44.144.1 to 137.44.159.254137.44.159.2554,094
203137.44.160.0/20137.44.160.1 to 137.44.175.254137.44.175.2554,094
204137.44.176.0/20137.44.176.1 to 137.44.191.254137.44.191.2554,094
205137.44.192.0/20137.44.192.1 to 137.44.207.254137.44.207.2554,094
206137.44.208.0/20137.44.208.1 to 137.44.223.254137.44.223.2554,094
207137.44.224.0/20137.44.224.1 to 137.44.239.254137.44.239.2554,094
208137.44.240.0/20137.44.240.1 to 137.44.255.254137.44.255.2554,094
209137.45.0.0/20137.45.0.1 to 137.45.15.254137.45.15.2554,094
210137.45.16.0/20137.45.16.1 to 137.45.31.254137.45.31.2554,094
211137.45.32.0/20137.45.32.1 to 137.45.47.254137.45.47.2554,094
212137.45.48.0/20137.45.48.1 to 137.45.63.254137.45.63.2554,094
213137.45.64.0/20137.45.64.1 to 137.45.79.254137.45.79.2554,094
214137.45.80.0/20137.45.80.1 to 137.45.95.254137.45.95.2554,094
215137.45.96.0/20137.45.96.1 to 137.45.111.254137.45.111.2554,094
216137.45.112.0/20137.45.112.1 to 137.45.127.254137.45.127.2554,094
217137.45.128.0/20137.45.128.1 to 137.45.143.254137.45.143.2554,094
218137.45.144.0/20137.45.144.1 to 137.45.159.254137.45.159.2554,094
219137.45.160.0/20137.45.160.1 to 137.45.175.254137.45.175.2554,094
220137.45.176.0/20137.45.176.1 to 137.45.191.254137.45.191.2554,094
221137.45.192.0/20137.45.192.1 to 137.45.207.254137.45.207.2554,094
222137.45.208.0/20137.45.208.1 to 137.45.223.254137.45.223.2554,094
223137.45.224.0/20137.45.224.1 to 137.45.239.254137.45.239.2554,094
224137.45.240.0/20137.45.240.1 to 137.45.255.254137.45.255.2554,094
225137.46.0.0/20137.46.0.1 to 137.46.15.254137.46.15.2554,094
226137.46.16.0/20137.46.16.1 to 137.46.31.254137.46.31.2554,094
227137.46.32.0/20137.46.32.1 to 137.46.47.254137.46.47.2554,094
228137.46.48.0/20137.46.48.1 to 137.46.63.254137.46.63.2554,094
229137.46.64.0/20137.46.64.1 to 137.46.79.254137.46.79.2554,094
230137.46.80.0/20137.46.80.1 to 137.46.95.254137.46.95.2554,094
231137.46.96.0/20137.46.96.1 to 137.46.111.254137.46.111.2554,094
232137.46.112.0/20137.46.112.1 to 137.46.127.254137.46.127.2554,094
233137.46.128.0/20137.46.128.1 to 137.46.143.254137.46.143.2554,094
234137.46.144.0/20137.46.144.1 to 137.46.159.254137.46.159.2554,094
235137.46.160.0/20137.46.160.1 to 137.46.175.254137.46.175.2554,094
236137.46.176.0/20137.46.176.1 to 137.46.191.254137.46.191.2554,094
237137.46.192.0/20137.46.192.1 to 137.46.207.254137.46.207.2554,094
238137.46.208.0/20137.46.208.1 to 137.46.223.254137.46.223.2554,094
239137.46.224.0/20137.46.224.1 to 137.46.239.254137.46.239.2554,094
240137.46.240.0/20137.46.240.1 to 137.46.255.254137.46.255.2554,094
241137.47.0.0/20137.47.0.1 to 137.47.15.254137.47.15.2554,094
242137.47.16.0/20137.47.16.1 to 137.47.31.254137.47.31.2554,094
243137.47.32.0/20137.47.32.1 to 137.47.47.254137.47.47.2554,094
244137.47.48.0/20137.47.48.1 to 137.47.63.254137.47.63.2554,094
245137.47.64.0/20137.47.64.1 to 137.47.79.254137.47.79.2554,094
246137.47.80.0/20137.47.80.1 to 137.47.95.254137.47.95.2554,094
247137.47.96.0/20137.47.96.1 to 137.47.111.254137.47.111.2554,094
248137.47.112.0/20137.47.112.1 to 137.47.127.254137.47.127.2554,094
249137.47.128.0/20137.47.128.1 to 137.47.143.254137.47.143.2554,094
250137.47.144.0/20137.47.144.1 to 137.47.159.254137.47.159.2554,094
251137.47.160.0/20137.47.160.1 to 137.47.175.254137.47.175.2554,094
252137.47.176.0/20137.47.176.1 to 137.47.191.254137.47.191.2554,094
253137.47.192.0/20137.47.192.1 to 137.47.207.254137.47.207.2554,094
254137.47.208.0/20137.47.208.1 to 137.47.223.254137.47.223.2554,094
255137.47.224.0/20137.47.224.1 to 137.47.239.254137.47.239.2554,094
256137.47.240.0/20137.47.240.1 to 137.47.255.254137.47.255.2554,094

IPv4 CIDR reference (/0 to /32)

IPv4 prefix lengths
PrefixSubnet maskWildcardAddressesUsable hostsSizeTypical use
/00.0.0.0255.255.255.2554,294,967,2964,294,967,29416,777,216 × /24
/1128.0.0.0127.255.255.2552,147,483,6482,147,483,6468,388,608 × /24
/2192.0.0.063.255.255.2551,073,741,8241,073,741,8224,194,304 × /24
/3224.0.0.031.255.255.255536,870,912536,870,9102,097,152 × /24
/4240.0.0.015.255.255.255268,435,456268,435,4541,048,576 × /24
/5248.0.0.07.255.255.255134,217,728134,217,726524,288 × /24
/6252.0.0.03.255.255.25567,108,86467,108,862262,144 × /24
/7254.0.0.01.255.255.25533,554,43233,554,430131,072 × /24
/8255.0.0.00.255.255.25516,777,21616,777,21465,536 × /24Old class A; 10.0.0.0/8
/9255.128.0.00.127.255.2558,388,6088,388,60632,768 × /24
/10255.192.0.00.63.255.2554,194,3044,194,30216,384 × /24
/11255.224.0.00.31.255.2552,097,1522,097,1508,192 × /24
/12255.240.0.00.15.255.2551,048,5761,048,5744,096 × /24172.16.0.0/12
/13255.248.0.00.7.255.255524,288524,2862,048 × /24
/14255.252.0.00.3.255.255262,144262,1421,024 × /24
/15255.254.0.00.1.255.255131,072131,070512 × /24
/16255.255.0.00.0.255.25565,53665,534256 × /24Old class B; 192.168.0.0/16
/17255.255.128.00.0.127.25532,76832,766128 × /24
/18255.255.192.00.0.63.25516,38416,38264 × /24
/19255.255.224.00.0.31.2558,1928,19032 × /24
/20255.255.240.00.0.15.2554,0964,09416 × /24
/21255.255.248.00.0.7.2552,0482,0468 × /24
/22255.255.252.00.0.3.2551,0241,0224 × /24Large office or guest Wi-Fi (1,022 hosts)
/23255.255.254.00.0.1.2555125102 × /24Larger office LAN (510 hosts)
/24255.255.255.00.0.0.2552562541 × /24Typical office LAN (old class C)
/25255.255.255.1280.0.0.1271281261/2 of a /24Smaller LAN or VLAN
/26255.255.255.1920.0.0.6364621/4 of a /24Smaller LAN or VLAN
/27255.255.255.2240.0.0.3132301/8 of a /24Small VLAN, phones, cameras
/28255.255.255.2400.0.0.1516141/16 of a /24Small VLAN, phones, cameras
/29255.255.255.2480.0.0.7861/32 of a /24Small fixed public block (5 usable)
/30255.255.255.2520.0.0.3421/64 of a /24Point-to-point (old style)
/31255.255.255.2540.0.0.1221/128 of a /24Point-to-point link (RFC 3021)
/32255.255.255.2550.0.0.0111/256 of a /24One host

IPv6 prefix reference

IPv6 prefix lengths
PrefixAddresses/64 LANs/48 sitesNibbleTypical use
/342,535,295,865,117,307,932,921,825,928,971,026,432 (2^125)2,305,843,009,213,693,95235,184,372,088,832NoAll global unicast (2000::/3)
/165,192,296,858,534,827,628,530,496,329,220,096 (2^112)281,474,976,710,6564,294,967,296Yes
/20324,518,553,658,426,726,783,156,020,576,256 (2^108)17,592,186,044,416268,435,456YesLarge provider allocation (RIPE minimum for some)
/29633,825,300,114,114,700,748,351,602,688 (2^99)34,359,738,368524,288NoRIPE allocation to a provider (often)
/3279,228,162,514,264,337,593,543,950,336 (2^96)4,294,967,29665,536YesProvider allocation (RIPE default)
/364,951,760,157,141,521,099,596,496,896 (2^92)268,435,4564,096Yes
/40309,485,009,821,345,068,724,781,056 (2^88)16,777,216256Yes
/4419,342,813,113,834,066,795,298,816 (2^84)1,048,57616Yes
/481,208,925,819,614,629,174,706,176 (2^80)65,5361YesOne site or organisation (RIPE PI / assignment)
/5275,557,863,725,914,323,419,136 (2^76)4,096Yes
/564,722,366,482,869,645,213,696 (2^72)256YesSmall site or home (common provider assignment)
/60295,147,905,179,352,825,856 (2^68)16YesSome home broadband (16 LANs)
/6418,446,744,073,709,551,616 (2^64)1YesOne LAN or VLAN (needed for SLAAC)
/7272,057,594,037,927,936 (2^56)1/256 of a /64Yes
/80281,474,976,710,656 (2^48)1/65,536 of a /64Yes
/964,294,967,2961/4,294,967,296 of a /64YesEmbeds an IPv4 address (NAT64)
/11265,5361/281,474,976,710,656 of a /64Yes
/1202561/72,057,594,037,927,936 of a /64Yes
/124161/1,152,921,504,606,846,976 of a /64Yes
/12641/4,611,686,018,427,387,904 of a /64No
/12721/9,223,372,036,854,775,808 of a /64NoPoint-to-point link (RFC 6164)
/12811/18,446,744,073,709,551,616 of a /64YesOne host or loopback

Private and special ranges

IPv4

Special-purpose ranges
RangeNameWhat it is
255.255.255.255/32Limited broadcastEvery host on the local network
0.0.0.0/8This networkNot routed; 0.0.0.0 means "any address" in settings
10.0.0.0/8Private (RFC 1918)Office and home networks; not routed on the internet
100.64.0.0/10Shared address space (CGNAT)Used by providers behind carrier-grade NAT (RFC 6598)
127.0.0.0/8LoopbackThis computer
169.254.0.0/16Link-local (APIPA)Self-assigned when no DHCP server answers
172.16.0.0/12Private (RFC 1918)Office and home networks; not routed on the internet
192.0.0.0/24IETF protocol assignmentsSpecial uses such as DS-Lite
192.0.2.0/24Documentation (TEST-NET-1)For examples; never used on a network
192.88.99.0/246to4 relay (deprecated)Formerly anycast for 6to4
192.168.0.0/16Private (RFC 1918)Office and home networks; not routed on the internet
198.18.0.0/15BenchmarkingNetwork equipment testing (RFC 2544)
198.51.100.0/24Documentation (TEST-NET-2)For examples; never used on a network
203.0.113.0/24Documentation (TEST-NET-3)For examples; never used on a network
224.0.0.0/4MulticastOne-to-many traffic, such as IPTV and routing protocols
240.0.0.0/4ReservedFuture use; not usable on most systems

IPv6

Special-purpose ranges
RangeNameWhat it is
::/128UnspecifiedNo address; :: means "any address" in settings
::1/128LoopbackThis computer
::ffff:0:0/96IPv4-mappedAn IPv4 address written as IPv6
64:ff9b::/96NAT64IPv4 addresses reached through a NAT64 gateway
100::/64Discard onlyTraffic sent here is dropped (RFC 6666)
2001:db8::/32DocumentationFor examples; never used on a network
2001::/32TeredoIPv6 tunnelled over IPv4 UDP
2002::/166to4IPv6 tunnelled over IPv4 (largely retired)
3fff::/20DocumentationFor examples (RFC 9637)
fc00::/7Unique local (ULA)Private IPv6, like RFC 1918; usually fd00::/8
fe80::/10Link-localEvery IPv6 interface has one; not routed
ff00::/8MulticastOne-to-many traffic; replaces broadcast
2000::/3Global unicastPublic internet addresses

About this tool

A network is written as an address and a prefix length, such as 192.168.1.0/24: the first 24 bits name the network and the rest number the devices on it. The calculator works out where the network starts and ends, how many devices it holds, its subnet and wildcard masks, and the reverse DNS zone to ask your provider for.

It also splits a network into equal smaller ones (one per VLAN or site), turns a range of addresses into the fewest CIDR blocks for a firewall rule, and lists every IPv4 prefix length and the common IPv6 ones in reference tables.

Common questions

Why are two addresses lost in every IPv4 subnet?

The first address names the network and the last is the broadcast address, so a /24 has 256 addresses but 254 for devices. A /31 (a link between two routers) and a /32 (one host) are the exceptions.

What size of IPv6 network should a LAN use?

Always /64. Devices pick their own address within it (SLAAC), which needs the full 64 bits. A site usually gets a /48 or /56 from its provider, which holds 65,536 or 256 LANs.

What is a wildcard mask?

The subnet mask turned inside out: 255.255.255.0 becomes 0.0.0.255. Cisco access lists and OSPF use it to say which bits must match.

Which ranges can I use inside an office?

IPv4: 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16. IPv6: unique local addresses from fd00::/8, though most networks use the public prefix from their provider.