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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.

Network156.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
156.0.0.0
Broadcast address
156.255.255.255
First usable
156.0.0.1
Last usable
156.255.255.254
Usable hosts
16,777,214 (16,777,216 less the network and broadcast addresses)
Subnet mask
255.0.0.0
Wildcard mask
0.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/8
Type
Public public
Old class
B (default /16)
As numbers
Hex 9C000000 · Integer 2617245696 to 2634022911
Reverse DNS zone
156.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10011100..00000000.00000000.00000000156.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network10011100..00000000.00000000.00000000156.0.0.0
Broadcast10011100..11111111.11111111.11111111156.255.255.255
Split into smaller subnets/19
/9 (2)/10 (4)/11 (8)/12 (16)/13 (32)/14 (64)/15 (128)/16 (256)/17 (512)/18 (1,024)/19 (2,048)/20 (4,096)

156.0.0.0/8 makes 2,048 subnets of /19; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1156.0.0.0/19156.0.0.1 to 156.0.31.254156.0.31.2558,190
2156.0.32.0/19156.0.32.1 to 156.0.63.254156.0.63.2558,190
3156.0.64.0/19156.0.64.1 to 156.0.95.254156.0.95.2558,190
4156.0.96.0/19156.0.96.1 to 156.0.127.254156.0.127.2558,190
5156.0.128.0/19156.0.128.1 to 156.0.159.254156.0.159.2558,190
6156.0.160.0/19156.0.160.1 to 156.0.191.254156.0.191.2558,190
7156.0.192.0/19156.0.192.1 to 156.0.223.254156.0.223.2558,190
8156.0.224.0/19156.0.224.1 to 156.0.255.254156.0.255.2558,190
9156.1.0.0/19156.1.0.1 to 156.1.31.254156.1.31.2558,190
10156.1.32.0/19156.1.32.1 to 156.1.63.254156.1.63.2558,190
11156.1.64.0/19156.1.64.1 to 156.1.95.254156.1.95.2558,190
12156.1.96.0/19156.1.96.1 to 156.1.127.254156.1.127.2558,190
13156.1.128.0/19156.1.128.1 to 156.1.159.254156.1.159.2558,190
14156.1.160.0/19156.1.160.1 to 156.1.191.254156.1.191.2558,190
15156.1.192.0/19156.1.192.1 to 156.1.223.254156.1.223.2558,190
16156.1.224.0/19156.1.224.1 to 156.1.255.254156.1.255.2558,190
17156.2.0.0/19156.2.0.1 to 156.2.31.254156.2.31.2558,190
18156.2.32.0/19156.2.32.1 to 156.2.63.254156.2.63.2558,190
19156.2.64.0/19156.2.64.1 to 156.2.95.254156.2.95.2558,190
20156.2.96.0/19156.2.96.1 to 156.2.127.254156.2.127.2558,190
21156.2.128.0/19156.2.128.1 to 156.2.159.254156.2.159.2558,190
22156.2.160.0/19156.2.160.1 to 156.2.191.254156.2.191.2558,190
23156.2.192.0/19156.2.192.1 to 156.2.223.254156.2.223.2558,190
24156.2.224.0/19156.2.224.1 to 156.2.255.254156.2.255.2558,190
25156.3.0.0/19156.3.0.1 to 156.3.31.254156.3.31.2558,190
26156.3.32.0/19156.3.32.1 to 156.3.63.254156.3.63.2558,190
27156.3.64.0/19156.3.64.1 to 156.3.95.254156.3.95.2558,190
28156.3.96.0/19156.3.96.1 to 156.3.127.254156.3.127.2558,190
29156.3.128.0/19156.3.128.1 to 156.3.159.254156.3.159.2558,190
30156.3.160.0/19156.3.160.1 to 156.3.191.254156.3.191.2558,190
31156.3.192.0/19156.3.192.1 to 156.3.223.254156.3.223.2558,190
32156.3.224.0/19156.3.224.1 to 156.3.255.254156.3.255.2558,190
33156.4.0.0/19156.4.0.1 to 156.4.31.254156.4.31.2558,190
34156.4.32.0/19156.4.32.1 to 156.4.63.254156.4.63.2558,190
35156.4.64.0/19156.4.64.1 to 156.4.95.254156.4.95.2558,190
36156.4.96.0/19156.4.96.1 to 156.4.127.254156.4.127.2558,190
37156.4.128.0/19156.4.128.1 to 156.4.159.254156.4.159.2558,190
38156.4.160.0/19156.4.160.1 to 156.4.191.254156.4.191.2558,190
39156.4.192.0/19156.4.192.1 to 156.4.223.254156.4.223.2558,190
40156.4.224.0/19156.4.224.1 to 156.4.255.254156.4.255.2558,190
41156.5.0.0/19156.5.0.1 to 156.5.31.254156.5.31.2558,190
42156.5.32.0/19156.5.32.1 to 156.5.63.254156.5.63.2558,190
43156.5.64.0/19156.5.64.1 to 156.5.95.254156.5.95.2558,190
44156.5.96.0/19156.5.96.1 to 156.5.127.254156.5.127.2558,190
45156.5.128.0/19156.5.128.1 to 156.5.159.254156.5.159.2558,190
46156.5.160.0/19156.5.160.1 to 156.5.191.254156.5.191.2558,190
47156.5.192.0/19156.5.192.1 to 156.5.223.254156.5.223.2558,190
48156.5.224.0/19156.5.224.1 to 156.5.255.254156.5.255.2558,190
49156.6.0.0/19156.6.0.1 to 156.6.31.254156.6.31.2558,190
50156.6.32.0/19156.6.32.1 to 156.6.63.254156.6.63.2558,190
51156.6.64.0/19156.6.64.1 to 156.6.95.254156.6.95.2558,190
52156.6.96.0/19156.6.96.1 to 156.6.127.254156.6.127.2558,190
53156.6.128.0/19156.6.128.1 to 156.6.159.254156.6.159.2558,190
54156.6.160.0/19156.6.160.1 to 156.6.191.254156.6.191.2558,190
55156.6.192.0/19156.6.192.1 to 156.6.223.254156.6.223.2558,190
56156.6.224.0/19156.6.224.1 to 156.6.255.254156.6.255.2558,190
57156.7.0.0/19156.7.0.1 to 156.7.31.254156.7.31.2558,190
58156.7.32.0/19156.7.32.1 to 156.7.63.254156.7.63.2558,190
59156.7.64.0/19156.7.64.1 to 156.7.95.254156.7.95.2558,190
60156.7.96.0/19156.7.96.1 to 156.7.127.254156.7.127.2558,190
61156.7.128.0/19156.7.128.1 to 156.7.159.254156.7.159.2558,190
62156.7.160.0/19156.7.160.1 to 156.7.191.254156.7.191.2558,190
63156.7.192.0/19156.7.192.1 to 156.7.223.254156.7.223.2558,190
64156.7.224.0/19156.7.224.1 to 156.7.255.254156.7.255.2558,190
65156.8.0.0/19156.8.0.1 to 156.8.31.254156.8.31.2558,190
66156.8.32.0/19156.8.32.1 to 156.8.63.254156.8.63.2558,190
67156.8.64.0/19156.8.64.1 to 156.8.95.254156.8.95.2558,190
68156.8.96.0/19156.8.96.1 to 156.8.127.254156.8.127.2558,190
69156.8.128.0/19156.8.128.1 to 156.8.159.254156.8.159.2558,190
70156.8.160.0/19156.8.160.1 to 156.8.191.254156.8.191.2558,190
71156.8.192.0/19156.8.192.1 to 156.8.223.254156.8.223.2558,190
72156.8.224.0/19156.8.224.1 to 156.8.255.254156.8.255.2558,190
73156.9.0.0/19156.9.0.1 to 156.9.31.254156.9.31.2558,190
74156.9.32.0/19156.9.32.1 to 156.9.63.254156.9.63.2558,190
75156.9.64.0/19156.9.64.1 to 156.9.95.254156.9.95.2558,190
76156.9.96.0/19156.9.96.1 to 156.9.127.254156.9.127.2558,190
77156.9.128.0/19156.9.128.1 to 156.9.159.254156.9.159.2558,190
78156.9.160.0/19156.9.160.1 to 156.9.191.254156.9.191.2558,190
79156.9.192.0/19156.9.192.1 to 156.9.223.254156.9.223.2558,190
80156.9.224.0/19156.9.224.1 to 156.9.255.254156.9.255.2558,190
81156.10.0.0/19156.10.0.1 to 156.10.31.254156.10.31.2558,190
82156.10.32.0/19156.10.32.1 to 156.10.63.254156.10.63.2558,190
83156.10.64.0/19156.10.64.1 to 156.10.95.254156.10.95.2558,190
84156.10.96.0/19156.10.96.1 to 156.10.127.254156.10.127.2558,190
85156.10.128.0/19156.10.128.1 to 156.10.159.254156.10.159.2558,190
86156.10.160.0/19156.10.160.1 to 156.10.191.254156.10.191.2558,190
87156.10.192.0/19156.10.192.1 to 156.10.223.254156.10.223.2558,190
88156.10.224.0/19156.10.224.1 to 156.10.255.254156.10.255.2558,190
89156.11.0.0/19156.11.0.1 to 156.11.31.254156.11.31.2558,190
90156.11.32.0/19156.11.32.1 to 156.11.63.254156.11.63.2558,190
91156.11.64.0/19156.11.64.1 to 156.11.95.254156.11.95.2558,190
92156.11.96.0/19156.11.96.1 to 156.11.127.254156.11.127.2558,190
93156.11.128.0/19156.11.128.1 to 156.11.159.254156.11.159.2558,190
94156.11.160.0/19156.11.160.1 to 156.11.191.254156.11.191.2558,190
95156.11.192.0/19156.11.192.1 to 156.11.223.254156.11.223.2558,190
96156.11.224.0/19156.11.224.1 to 156.11.255.254156.11.255.2558,190
97156.12.0.0/19156.12.0.1 to 156.12.31.254156.12.31.2558,190
98156.12.32.0/19156.12.32.1 to 156.12.63.254156.12.63.2558,190
99156.12.64.0/19156.12.64.1 to 156.12.95.254156.12.95.2558,190
100156.12.96.0/19156.12.96.1 to 156.12.127.254156.12.127.2558,190
101156.12.128.0/19156.12.128.1 to 156.12.159.254156.12.159.2558,190
102156.12.160.0/19156.12.160.1 to 156.12.191.254156.12.191.2558,190
103156.12.192.0/19156.12.192.1 to 156.12.223.254156.12.223.2558,190
104156.12.224.0/19156.12.224.1 to 156.12.255.254156.12.255.2558,190
105156.13.0.0/19156.13.0.1 to 156.13.31.254156.13.31.2558,190
106156.13.32.0/19156.13.32.1 to 156.13.63.254156.13.63.2558,190
107156.13.64.0/19156.13.64.1 to 156.13.95.254156.13.95.2558,190
108156.13.96.0/19156.13.96.1 to 156.13.127.254156.13.127.2558,190
109156.13.128.0/19156.13.128.1 to 156.13.159.254156.13.159.2558,190
110156.13.160.0/19156.13.160.1 to 156.13.191.254156.13.191.2558,190
111156.13.192.0/19156.13.192.1 to 156.13.223.254156.13.223.2558,190
112156.13.224.0/19156.13.224.1 to 156.13.255.254156.13.255.2558,190
113156.14.0.0/19156.14.0.1 to 156.14.31.254156.14.31.2558,190
114156.14.32.0/19156.14.32.1 to 156.14.63.254156.14.63.2558,190
115156.14.64.0/19156.14.64.1 to 156.14.95.254156.14.95.2558,190
116156.14.96.0/19156.14.96.1 to 156.14.127.254156.14.127.2558,190
117156.14.128.0/19156.14.128.1 to 156.14.159.254156.14.159.2558,190
118156.14.160.0/19156.14.160.1 to 156.14.191.254156.14.191.2558,190
119156.14.192.0/19156.14.192.1 to 156.14.223.254156.14.223.2558,190
120156.14.224.0/19156.14.224.1 to 156.14.255.254156.14.255.2558,190
121156.15.0.0/19156.15.0.1 to 156.15.31.254156.15.31.2558,190
122156.15.32.0/19156.15.32.1 to 156.15.63.254156.15.63.2558,190
123156.15.64.0/19156.15.64.1 to 156.15.95.254156.15.95.2558,190
124156.15.96.0/19156.15.96.1 to 156.15.127.254156.15.127.2558,190
125156.15.128.0/19156.15.128.1 to 156.15.159.254156.15.159.2558,190
126156.15.160.0/19156.15.160.1 to 156.15.191.254156.15.191.2558,190
127156.15.192.0/19156.15.192.1 to 156.15.223.254156.15.223.2558,190
128156.15.224.0/19156.15.224.1 to 156.15.255.254156.15.255.2558,190
129156.16.0.0/19156.16.0.1 to 156.16.31.254156.16.31.2558,190
130156.16.32.0/19156.16.32.1 to 156.16.63.254156.16.63.2558,190
131156.16.64.0/19156.16.64.1 to 156.16.95.254156.16.95.2558,190
132156.16.96.0/19156.16.96.1 to 156.16.127.254156.16.127.2558,190
133156.16.128.0/19156.16.128.1 to 156.16.159.254156.16.159.2558,190
134156.16.160.0/19156.16.160.1 to 156.16.191.254156.16.191.2558,190
135156.16.192.0/19156.16.192.1 to 156.16.223.254156.16.223.2558,190
136156.16.224.0/19156.16.224.1 to 156.16.255.254156.16.255.2558,190
137156.17.0.0/19156.17.0.1 to 156.17.31.254156.17.31.2558,190
138156.17.32.0/19156.17.32.1 to 156.17.63.254156.17.63.2558,190
139156.17.64.0/19156.17.64.1 to 156.17.95.254156.17.95.2558,190
140156.17.96.0/19156.17.96.1 to 156.17.127.254156.17.127.2558,190
141156.17.128.0/19156.17.128.1 to 156.17.159.254156.17.159.2558,190
142156.17.160.0/19156.17.160.1 to 156.17.191.254156.17.191.2558,190
143156.17.192.0/19156.17.192.1 to 156.17.223.254156.17.223.2558,190
144156.17.224.0/19156.17.224.1 to 156.17.255.254156.17.255.2558,190
145156.18.0.0/19156.18.0.1 to 156.18.31.254156.18.31.2558,190
146156.18.32.0/19156.18.32.1 to 156.18.63.254156.18.63.2558,190
147156.18.64.0/19156.18.64.1 to 156.18.95.254156.18.95.2558,190
148156.18.96.0/19156.18.96.1 to 156.18.127.254156.18.127.2558,190
149156.18.128.0/19156.18.128.1 to 156.18.159.254156.18.159.2558,190
150156.18.160.0/19156.18.160.1 to 156.18.191.254156.18.191.2558,190
151156.18.192.0/19156.18.192.1 to 156.18.223.254156.18.223.2558,190
152156.18.224.0/19156.18.224.1 to 156.18.255.254156.18.255.2558,190
153156.19.0.0/19156.19.0.1 to 156.19.31.254156.19.31.2558,190
154156.19.32.0/19156.19.32.1 to 156.19.63.254156.19.63.2558,190
155156.19.64.0/19156.19.64.1 to 156.19.95.254156.19.95.2558,190
156156.19.96.0/19156.19.96.1 to 156.19.127.254156.19.127.2558,190
157156.19.128.0/19156.19.128.1 to 156.19.159.254156.19.159.2558,190
158156.19.160.0/19156.19.160.1 to 156.19.191.254156.19.191.2558,190
159156.19.192.0/19156.19.192.1 to 156.19.223.254156.19.223.2558,190
160156.19.224.0/19156.19.224.1 to 156.19.255.254156.19.255.2558,190
161156.20.0.0/19156.20.0.1 to 156.20.31.254156.20.31.2558,190
162156.20.32.0/19156.20.32.1 to 156.20.63.254156.20.63.2558,190
163156.20.64.0/19156.20.64.1 to 156.20.95.254156.20.95.2558,190
164156.20.96.0/19156.20.96.1 to 156.20.127.254156.20.127.2558,190
165156.20.128.0/19156.20.128.1 to 156.20.159.254156.20.159.2558,190
166156.20.160.0/19156.20.160.1 to 156.20.191.254156.20.191.2558,190
167156.20.192.0/19156.20.192.1 to 156.20.223.254156.20.223.2558,190
168156.20.224.0/19156.20.224.1 to 156.20.255.254156.20.255.2558,190
169156.21.0.0/19156.21.0.1 to 156.21.31.254156.21.31.2558,190
170156.21.32.0/19156.21.32.1 to 156.21.63.254156.21.63.2558,190
171156.21.64.0/19156.21.64.1 to 156.21.95.254156.21.95.2558,190
172156.21.96.0/19156.21.96.1 to 156.21.127.254156.21.127.2558,190
173156.21.128.0/19156.21.128.1 to 156.21.159.254156.21.159.2558,190
174156.21.160.0/19156.21.160.1 to 156.21.191.254156.21.191.2558,190
175156.21.192.0/19156.21.192.1 to 156.21.223.254156.21.223.2558,190
176156.21.224.0/19156.21.224.1 to 156.21.255.254156.21.255.2558,190
177156.22.0.0/19156.22.0.1 to 156.22.31.254156.22.31.2558,190
178156.22.32.0/19156.22.32.1 to 156.22.63.254156.22.63.2558,190
179156.22.64.0/19156.22.64.1 to 156.22.95.254156.22.95.2558,190
180156.22.96.0/19156.22.96.1 to 156.22.127.254156.22.127.2558,190
181156.22.128.0/19156.22.128.1 to 156.22.159.254156.22.159.2558,190
182156.22.160.0/19156.22.160.1 to 156.22.191.254156.22.191.2558,190
183156.22.192.0/19156.22.192.1 to 156.22.223.254156.22.223.2558,190
184156.22.224.0/19156.22.224.1 to 156.22.255.254156.22.255.2558,190
185156.23.0.0/19156.23.0.1 to 156.23.31.254156.23.31.2558,190
186156.23.32.0/19156.23.32.1 to 156.23.63.254156.23.63.2558,190
187156.23.64.0/19156.23.64.1 to 156.23.95.254156.23.95.2558,190
188156.23.96.0/19156.23.96.1 to 156.23.127.254156.23.127.2558,190
189156.23.128.0/19156.23.128.1 to 156.23.159.254156.23.159.2558,190
190156.23.160.0/19156.23.160.1 to 156.23.191.254156.23.191.2558,190
191156.23.192.0/19156.23.192.1 to 156.23.223.254156.23.223.2558,190
192156.23.224.0/19156.23.224.1 to 156.23.255.254156.23.255.2558,190
193156.24.0.0/19156.24.0.1 to 156.24.31.254156.24.31.2558,190
194156.24.32.0/19156.24.32.1 to 156.24.63.254156.24.63.2558,190
195156.24.64.0/19156.24.64.1 to 156.24.95.254156.24.95.2558,190
196156.24.96.0/19156.24.96.1 to 156.24.127.254156.24.127.2558,190
197156.24.128.0/19156.24.128.1 to 156.24.159.254156.24.159.2558,190
198156.24.160.0/19156.24.160.1 to 156.24.191.254156.24.191.2558,190
199156.24.192.0/19156.24.192.1 to 156.24.223.254156.24.223.2558,190
200156.24.224.0/19156.24.224.1 to 156.24.255.254156.24.255.2558,190
201156.25.0.0/19156.25.0.1 to 156.25.31.254156.25.31.2558,190
202156.25.32.0/19156.25.32.1 to 156.25.63.254156.25.63.2558,190
203156.25.64.0/19156.25.64.1 to 156.25.95.254156.25.95.2558,190
204156.25.96.0/19156.25.96.1 to 156.25.127.254156.25.127.2558,190
205156.25.128.0/19156.25.128.1 to 156.25.159.254156.25.159.2558,190
206156.25.160.0/19156.25.160.1 to 156.25.191.254156.25.191.2558,190
207156.25.192.0/19156.25.192.1 to 156.25.223.254156.25.223.2558,190
208156.25.224.0/19156.25.224.1 to 156.25.255.254156.25.255.2558,190
209156.26.0.0/19156.26.0.1 to 156.26.31.254156.26.31.2558,190
210156.26.32.0/19156.26.32.1 to 156.26.63.254156.26.63.2558,190
211156.26.64.0/19156.26.64.1 to 156.26.95.254156.26.95.2558,190
212156.26.96.0/19156.26.96.1 to 156.26.127.254156.26.127.2558,190
213156.26.128.0/19156.26.128.1 to 156.26.159.254156.26.159.2558,190
214156.26.160.0/19156.26.160.1 to 156.26.191.254156.26.191.2558,190
215156.26.192.0/19156.26.192.1 to 156.26.223.254156.26.223.2558,190
216156.26.224.0/19156.26.224.1 to 156.26.255.254156.26.255.2558,190
217156.27.0.0/19156.27.0.1 to 156.27.31.254156.27.31.2558,190
218156.27.32.0/19156.27.32.1 to 156.27.63.254156.27.63.2558,190
219156.27.64.0/19156.27.64.1 to 156.27.95.254156.27.95.2558,190
220156.27.96.0/19156.27.96.1 to 156.27.127.254156.27.127.2558,190
221156.27.128.0/19156.27.128.1 to 156.27.159.254156.27.159.2558,190
222156.27.160.0/19156.27.160.1 to 156.27.191.254156.27.191.2558,190
223156.27.192.0/19156.27.192.1 to 156.27.223.254156.27.223.2558,190
224156.27.224.0/19156.27.224.1 to 156.27.255.254156.27.255.2558,190
225156.28.0.0/19156.28.0.1 to 156.28.31.254156.28.31.2558,190
226156.28.32.0/19156.28.32.1 to 156.28.63.254156.28.63.2558,190
227156.28.64.0/19156.28.64.1 to 156.28.95.254156.28.95.2558,190
228156.28.96.0/19156.28.96.1 to 156.28.127.254156.28.127.2558,190
229156.28.128.0/19156.28.128.1 to 156.28.159.254156.28.159.2558,190
230156.28.160.0/19156.28.160.1 to 156.28.191.254156.28.191.2558,190
231156.28.192.0/19156.28.192.1 to 156.28.223.254156.28.223.2558,190
232156.28.224.0/19156.28.224.1 to 156.28.255.254156.28.255.2558,190
233156.29.0.0/19156.29.0.1 to 156.29.31.254156.29.31.2558,190
234156.29.32.0/19156.29.32.1 to 156.29.63.254156.29.63.2558,190
235156.29.64.0/19156.29.64.1 to 156.29.95.254156.29.95.2558,190
236156.29.96.0/19156.29.96.1 to 156.29.127.254156.29.127.2558,190
237156.29.128.0/19156.29.128.1 to 156.29.159.254156.29.159.2558,190
238156.29.160.0/19156.29.160.1 to 156.29.191.254156.29.191.2558,190
239156.29.192.0/19156.29.192.1 to 156.29.223.254156.29.223.2558,190
240156.29.224.0/19156.29.224.1 to 156.29.255.254156.29.255.2558,190
241156.30.0.0/19156.30.0.1 to 156.30.31.254156.30.31.2558,190
242156.30.32.0/19156.30.32.1 to 156.30.63.254156.30.63.2558,190
243156.30.64.0/19156.30.64.1 to 156.30.95.254156.30.95.2558,190
244156.30.96.0/19156.30.96.1 to 156.30.127.254156.30.127.2558,190
245156.30.128.0/19156.30.128.1 to 156.30.159.254156.30.159.2558,190
246156.30.160.0/19156.30.160.1 to 156.30.191.254156.30.191.2558,190
247156.30.192.0/19156.30.192.1 to 156.30.223.254156.30.223.2558,190
248156.30.224.0/19156.30.224.1 to 156.30.255.254156.30.255.2558,190
249156.31.0.0/19156.31.0.1 to 156.31.31.254156.31.31.2558,190
250156.31.32.0/19156.31.32.1 to 156.31.63.254156.31.63.2558,190
251156.31.64.0/19156.31.64.1 to 156.31.95.254156.31.95.2558,190
252156.31.96.0/19156.31.96.1 to 156.31.127.254156.31.127.2558,190
253156.31.128.0/19156.31.128.1 to 156.31.159.254156.31.159.2558,190
254156.31.160.0/19156.31.160.1 to 156.31.191.254156.31.191.2558,190
255156.31.192.0/19156.31.192.1 to 156.31.223.254156.31.223.2558,190
256156.31.224.0/19156.31.224.1 to 156.31.255.254156.31.255.2558,190

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.