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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.

Network252.0.0.0/12
Usable hosts1,048,574
Subnet mask255.240.0.0
Addresses1,048,576
Network address
252.0.0.0
Broadcast address
252.15.255.255
First usable
252.0.0.1
Last usable
252.15.255.254
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
Reserved 240.0.0.0/4
Future use; not usable on most systems
Old class
E (reserved)
As numbers
Hex FC000000 · Integer 4227858432 to 4228907007
Reverse DNS zones
0.252.in-addr.arpa
1.252.in-addr.arpa
2.252.in-addr.arpa
3.252.in-addr.arpa
4.252.in-addr.arpa
5.252.in-addr.arpa
6.252.in-addr.arpa
7.252.in-addr.arpa
8.252.in-addr.arpa
9.252.in-addr.arpa
10.252.in-addr.arpa
11.252.in-addr.arpa
12.252.in-addr.arpa
13.252.in-addr.arpa
14.252.in-addr.arpa
15.252.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
Address11111100.00000000.00000000.00000000252.0.0.0
Subnet mask11111111.11110000.00000000.00000000255.240.0.0
Network11111100.00000000.00000000.00000000252.0.0.0
Broadcast11111100.00001111.11111111.11111111252.15.255.255
Split into smaller subnets/21
/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)

252.0.0.0/12 makes 512 subnets of /21; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1252.0.0.0/21252.0.0.1 to 252.0.7.254252.0.7.2552,046
2252.0.8.0/21252.0.8.1 to 252.0.15.254252.0.15.2552,046
3252.0.16.0/21252.0.16.1 to 252.0.23.254252.0.23.2552,046
4252.0.24.0/21252.0.24.1 to 252.0.31.254252.0.31.2552,046
5252.0.32.0/21252.0.32.1 to 252.0.39.254252.0.39.2552,046
6252.0.40.0/21252.0.40.1 to 252.0.47.254252.0.47.2552,046
7252.0.48.0/21252.0.48.1 to 252.0.55.254252.0.55.2552,046
8252.0.56.0/21252.0.56.1 to 252.0.63.254252.0.63.2552,046
9252.0.64.0/21252.0.64.1 to 252.0.71.254252.0.71.2552,046
10252.0.72.0/21252.0.72.1 to 252.0.79.254252.0.79.2552,046
11252.0.80.0/21252.0.80.1 to 252.0.87.254252.0.87.2552,046
12252.0.88.0/21252.0.88.1 to 252.0.95.254252.0.95.2552,046
13252.0.96.0/21252.0.96.1 to 252.0.103.254252.0.103.2552,046
14252.0.104.0/21252.0.104.1 to 252.0.111.254252.0.111.2552,046
15252.0.112.0/21252.0.112.1 to 252.0.119.254252.0.119.2552,046
16252.0.120.0/21252.0.120.1 to 252.0.127.254252.0.127.2552,046
17252.0.128.0/21252.0.128.1 to 252.0.135.254252.0.135.2552,046
18252.0.136.0/21252.0.136.1 to 252.0.143.254252.0.143.2552,046
19252.0.144.0/21252.0.144.1 to 252.0.151.254252.0.151.2552,046
20252.0.152.0/21252.0.152.1 to 252.0.159.254252.0.159.2552,046
21252.0.160.0/21252.0.160.1 to 252.0.167.254252.0.167.2552,046
22252.0.168.0/21252.0.168.1 to 252.0.175.254252.0.175.2552,046
23252.0.176.0/21252.0.176.1 to 252.0.183.254252.0.183.2552,046
24252.0.184.0/21252.0.184.1 to 252.0.191.254252.0.191.2552,046
25252.0.192.0/21252.0.192.1 to 252.0.199.254252.0.199.2552,046
26252.0.200.0/21252.0.200.1 to 252.0.207.254252.0.207.2552,046
27252.0.208.0/21252.0.208.1 to 252.0.215.254252.0.215.2552,046
28252.0.216.0/21252.0.216.1 to 252.0.223.254252.0.223.2552,046
29252.0.224.0/21252.0.224.1 to 252.0.231.254252.0.231.2552,046
30252.0.232.0/21252.0.232.1 to 252.0.239.254252.0.239.2552,046
31252.0.240.0/21252.0.240.1 to 252.0.247.254252.0.247.2552,046
32252.0.248.0/21252.0.248.1 to 252.0.255.254252.0.255.2552,046
33252.1.0.0/21252.1.0.1 to 252.1.7.254252.1.7.2552,046
34252.1.8.0/21252.1.8.1 to 252.1.15.254252.1.15.2552,046
35252.1.16.0/21252.1.16.1 to 252.1.23.254252.1.23.2552,046
36252.1.24.0/21252.1.24.1 to 252.1.31.254252.1.31.2552,046
37252.1.32.0/21252.1.32.1 to 252.1.39.254252.1.39.2552,046
38252.1.40.0/21252.1.40.1 to 252.1.47.254252.1.47.2552,046
39252.1.48.0/21252.1.48.1 to 252.1.55.254252.1.55.2552,046
40252.1.56.0/21252.1.56.1 to 252.1.63.254252.1.63.2552,046
41252.1.64.0/21252.1.64.1 to 252.1.71.254252.1.71.2552,046
42252.1.72.0/21252.1.72.1 to 252.1.79.254252.1.79.2552,046
43252.1.80.0/21252.1.80.1 to 252.1.87.254252.1.87.2552,046
44252.1.88.0/21252.1.88.1 to 252.1.95.254252.1.95.2552,046
45252.1.96.0/21252.1.96.1 to 252.1.103.254252.1.103.2552,046
46252.1.104.0/21252.1.104.1 to 252.1.111.254252.1.111.2552,046
47252.1.112.0/21252.1.112.1 to 252.1.119.254252.1.119.2552,046
48252.1.120.0/21252.1.120.1 to 252.1.127.254252.1.127.2552,046
49252.1.128.0/21252.1.128.1 to 252.1.135.254252.1.135.2552,046
50252.1.136.0/21252.1.136.1 to 252.1.143.254252.1.143.2552,046
51252.1.144.0/21252.1.144.1 to 252.1.151.254252.1.151.2552,046
52252.1.152.0/21252.1.152.1 to 252.1.159.254252.1.159.2552,046
53252.1.160.0/21252.1.160.1 to 252.1.167.254252.1.167.2552,046
54252.1.168.0/21252.1.168.1 to 252.1.175.254252.1.175.2552,046
55252.1.176.0/21252.1.176.1 to 252.1.183.254252.1.183.2552,046
56252.1.184.0/21252.1.184.1 to 252.1.191.254252.1.191.2552,046
57252.1.192.0/21252.1.192.1 to 252.1.199.254252.1.199.2552,046
58252.1.200.0/21252.1.200.1 to 252.1.207.254252.1.207.2552,046
59252.1.208.0/21252.1.208.1 to 252.1.215.254252.1.215.2552,046
60252.1.216.0/21252.1.216.1 to 252.1.223.254252.1.223.2552,046
61252.1.224.0/21252.1.224.1 to 252.1.231.254252.1.231.2552,046
62252.1.232.0/21252.1.232.1 to 252.1.239.254252.1.239.2552,046
63252.1.240.0/21252.1.240.1 to 252.1.247.254252.1.247.2552,046
64252.1.248.0/21252.1.248.1 to 252.1.255.254252.1.255.2552,046
65252.2.0.0/21252.2.0.1 to 252.2.7.254252.2.7.2552,046
66252.2.8.0/21252.2.8.1 to 252.2.15.254252.2.15.2552,046
67252.2.16.0/21252.2.16.1 to 252.2.23.254252.2.23.2552,046
68252.2.24.0/21252.2.24.1 to 252.2.31.254252.2.31.2552,046
69252.2.32.0/21252.2.32.1 to 252.2.39.254252.2.39.2552,046
70252.2.40.0/21252.2.40.1 to 252.2.47.254252.2.47.2552,046
71252.2.48.0/21252.2.48.1 to 252.2.55.254252.2.55.2552,046
72252.2.56.0/21252.2.56.1 to 252.2.63.254252.2.63.2552,046
73252.2.64.0/21252.2.64.1 to 252.2.71.254252.2.71.2552,046
74252.2.72.0/21252.2.72.1 to 252.2.79.254252.2.79.2552,046
75252.2.80.0/21252.2.80.1 to 252.2.87.254252.2.87.2552,046
76252.2.88.0/21252.2.88.1 to 252.2.95.254252.2.95.2552,046
77252.2.96.0/21252.2.96.1 to 252.2.103.254252.2.103.2552,046
78252.2.104.0/21252.2.104.1 to 252.2.111.254252.2.111.2552,046
79252.2.112.0/21252.2.112.1 to 252.2.119.254252.2.119.2552,046
80252.2.120.0/21252.2.120.1 to 252.2.127.254252.2.127.2552,046
81252.2.128.0/21252.2.128.1 to 252.2.135.254252.2.135.2552,046
82252.2.136.0/21252.2.136.1 to 252.2.143.254252.2.143.2552,046
83252.2.144.0/21252.2.144.1 to 252.2.151.254252.2.151.2552,046
84252.2.152.0/21252.2.152.1 to 252.2.159.254252.2.159.2552,046
85252.2.160.0/21252.2.160.1 to 252.2.167.254252.2.167.2552,046
86252.2.168.0/21252.2.168.1 to 252.2.175.254252.2.175.2552,046
87252.2.176.0/21252.2.176.1 to 252.2.183.254252.2.183.2552,046
88252.2.184.0/21252.2.184.1 to 252.2.191.254252.2.191.2552,046
89252.2.192.0/21252.2.192.1 to 252.2.199.254252.2.199.2552,046
90252.2.200.0/21252.2.200.1 to 252.2.207.254252.2.207.2552,046
91252.2.208.0/21252.2.208.1 to 252.2.215.254252.2.215.2552,046
92252.2.216.0/21252.2.216.1 to 252.2.223.254252.2.223.2552,046
93252.2.224.0/21252.2.224.1 to 252.2.231.254252.2.231.2552,046
94252.2.232.0/21252.2.232.1 to 252.2.239.254252.2.239.2552,046
95252.2.240.0/21252.2.240.1 to 252.2.247.254252.2.247.2552,046
96252.2.248.0/21252.2.248.1 to 252.2.255.254252.2.255.2552,046
97252.3.0.0/21252.3.0.1 to 252.3.7.254252.3.7.2552,046
98252.3.8.0/21252.3.8.1 to 252.3.15.254252.3.15.2552,046
99252.3.16.0/21252.3.16.1 to 252.3.23.254252.3.23.2552,046
100252.3.24.0/21252.3.24.1 to 252.3.31.254252.3.31.2552,046
101252.3.32.0/21252.3.32.1 to 252.3.39.254252.3.39.2552,046
102252.3.40.0/21252.3.40.1 to 252.3.47.254252.3.47.2552,046
103252.3.48.0/21252.3.48.1 to 252.3.55.254252.3.55.2552,046
104252.3.56.0/21252.3.56.1 to 252.3.63.254252.3.63.2552,046
105252.3.64.0/21252.3.64.1 to 252.3.71.254252.3.71.2552,046
106252.3.72.0/21252.3.72.1 to 252.3.79.254252.3.79.2552,046
107252.3.80.0/21252.3.80.1 to 252.3.87.254252.3.87.2552,046
108252.3.88.0/21252.3.88.1 to 252.3.95.254252.3.95.2552,046
109252.3.96.0/21252.3.96.1 to 252.3.103.254252.3.103.2552,046
110252.3.104.0/21252.3.104.1 to 252.3.111.254252.3.111.2552,046
111252.3.112.0/21252.3.112.1 to 252.3.119.254252.3.119.2552,046
112252.3.120.0/21252.3.120.1 to 252.3.127.254252.3.127.2552,046
113252.3.128.0/21252.3.128.1 to 252.3.135.254252.3.135.2552,046
114252.3.136.0/21252.3.136.1 to 252.3.143.254252.3.143.2552,046
115252.3.144.0/21252.3.144.1 to 252.3.151.254252.3.151.2552,046
116252.3.152.0/21252.3.152.1 to 252.3.159.254252.3.159.2552,046
117252.3.160.0/21252.3.160.1 to 252.3.167.254252.3.167.2552,046
118252.3.168.0/21252.3.168.1 to 252.3.175.254252.3.175.2552,046
119252.3.176.0/21252.3.176.1 to 252.3.183.254252.3.183.2552,046
120252.3.184.0/21252.3.184.1 to 252.3.191.254252.3.191.2552,046
121252.3.192.0/21252.3.192.1 to 252.3.199.254252.3.199.2552,046
122252.3.200.0/21252.3.200.1 to 252.3.207.254252.3.207.2552,046
123252.3.208.0/21252.3.208.1 to 252.3.215.254252.3.215.2552,046
124252.3.216.0/21252.3.216.1 to 252.3.223.254252.3.223.2552,046
125252.3.224.0/21252.3.224.1 to 252.3.231.254252.3.231.2552,046
126252.3.232.0/21252.3.232.1 to 252.3.239.254252.3.239.2552,046
127252.3.240.0/21252.3.240.1 to 252.3.247.254252.3.247.2552,046
128252.3.248.0/21252.3.248.1 to 252.3.255.254252.3.255.2552,046
129252.4.0.0/21252.4.0.1 to 252.4.7.254252.4.7.2552,046
130252.4.8.0/21252.4.8.1 to 252.4.15.254252.4.15.2552,046
131252.4.16.0/21252.4.16.1 to 252.4.23.254252.4.23.2552,046
132252.4.24.0/21252.4.24.1 to 252.4.31.254252.4.31.2552,046
133252.4.32.0/21252.4.32.1 to 252.4.39.254252.4.39.2552,046
134252.4.40.0/21252.4.40.1 to 252.4.47.254252.4.47.2552,046
135252.4.48.0/21252.4.48.1 to 252.4.55.254252.4.55.2552,046
136252.4.56.0/21252.4.56.1 to 252.4.63.254252.4.63.2552,046
137252.4.64.0/21252.4.64.1 to 252.4.71.254252.4.71.2552,046
138252.4.72.0/21252.4.72.1 to 252.4.79.254252.4.79.2552,046
139252.4.80.0/21252.4.80.1 to 252.4.87.254252.4.87.2552,046
140252.4.88.0/21252.4.88.1 to 252.4.95.254252.4.95.2552,046
141252.4.96.0/21252.4.96.1 to 252.4.103.254252.4.103.2552,046
142252.4.104.0/21252.4.104.1 to 252.4.111.254252.4.111.2552,046
143252.4.112.0/21252.4.112.1 to 252.4.119.254252.4.119.2552,046
144252.4.120.0/21252.4.120.1 to 252.4.127.254252.4.127.2552,046
145252.4.128.0/21252.4.128.1 to 252.4.135.254252.4.135.2552,046
146252.4.136.0/21252.4.136.1 to 252.4.143.254252.4.143.2552,046
147252.4.144.0/21252.4.144.1 to 252.4.151.254252.4.151.2552,046
148252.4.152.0/21252.4.152.1 to 252.4.159.254252.4.159.2552,046
149252.4.160.0/21252.4.160.1 to 252.4.167.254252.4.167.2552,046
150252.4.168.0/21252.4.168.1 to 252.4.175.254252.4.175.2552,046
151252.4.176.0/21252.4.176.1 to 252.4.183.254252.4.183.2552,046
152252.4.184.0/21252.4.184.1 to 252.4.191.254252.4.191.2552,046
153252.4.192.0/21252.4.192.1 to 252.4.199.254252.4.199.2552,046
154252.4.200.0/21252.4.200.1 to 252.4.207.254252.4.207.2552,046
155252.4.208.0/21252.4.208.1 to 252.4.215.254252.4.215.2552,046
156252.4.216.0/21252.4.216.1 to 252.4.223.254252.4.223.2552,046
157252.4.224.0/21252.4.224.1 to 252.4.231.254252.4.231.2552,046
158252.4.232.0/21252.4.232.1 to 252.4.239.254252.4.239.2552,046
159252.4.240.0/21252.4.240.1 to 252.4.247.254252.4.247.2552,046
160252.4.248.0/21252.4.248.1 to 252.4.255.254252.4.255.2552,046
161252.5.0.0/21252.5.0.1 to 252.5.7.254252.5.7.2552,046
162252.5.8.0/21252.5.8.1 to 252.5.15.254252.5.15.2552,046
163252.5.16.0/21252.5.16.1 to 252.5.23.254252.5.23.2552,046
164252.5.24.0/21252.5.24.1 to 252.5.31.254252.5.31.2552,046
165252.5.32.0/21252.5.32.1 to 252.5.39.254252.5.39.2552,046
166252.5.40.0/21252.5.40.1 to 252.5.47.254252.5.47.2552,046
167252.5.48.0/21252.5.48.1 to 252.5.55.254252.5.55.2552,046
168252.5.56.0/21252.5.56.1 to 252.5.63.254252.5.63.2552,046
169252.5.64.0/21252.5.64.1 to 252.5.71.254252.5.71.2552,046
170252.5.72.0/21252.5.72.1 to 252.5.79.254252.5.79.2552,046
171252.5.80.0/21252.5.80.1 to 252.5.87.254252.5.87.2552,046
172252.5.88.0/21252.5.88.1 to 252.5.95.254252.5.95.2552,046
173252.5.96.0/21252.5.96.1 to 252.5.103.254252.5.103.2552,046
174252.5.104.0/21252.5.104.1 to 252.5.111.254252.5.111.2552,046
175252.5.112.0/21252.5.112.1 to 252.5.119.254252.5.119.2552,046
176252.5.120.0/21252.5.120.1 to 252.5.127.254252.5.127.2552,046
177252.5.128.0/21252.5.128.1 to 252.5.135.254252.5.135.2552,046
178252.5.136.0/21252.5.136.1 to 252.5.143.254252.5.143.2552,046
179252.5.144.0/21252.5.144.1 to 252.5.151.254252.5.151.2552,046
180252.5.152.0/21252.5.152.1 to 252.5.159.254252.5.159.2552,046
181252.5.160.0/21252.5.160.1 to 252.5.167.254252.5.167.2552,046
182252.5.168.0/21252.5.168.1 to 252.5.175.254252.5.175.2552,046
183252.5.176.0/21252.5.176.1 to 252.5.183.254252.5.183.2552,046
184252.5.184.0/21252.5.184.1 to 252.5.191.254252.5.191.2552,046
185252.5.192.0/21252.5.192.1 to 252.5.199.254252.5.199.2552,046
186252.5.200.0/21252.5.200.1 to 252.5.207.254252.5.207.2552,046
187252.5.208.0/21252.5.208.1 to 252.5.215.254252.5.215.2552,046
188252.5.216.0/21252.5.216.1 to 252.5.223.254252.5.223.2552,046
189252.5.224.0/21252.5.224.1 to 252.5.231.254252.5.231.2552,046
190252.5.232.0/21252.5.232.1 to 252.5.239.254252.5.239.2552,046
191252.5.240.0/21252.5.240.1 to 252.5.247.254252.5.247.2552,046
192252.5.248.0/21252.5.248.1 to 252.5.255.254252.5.255.2552,046
193252.6.0.0/21252.6.0.1 to 252.6.7.254252.6.7.2552,046
194252.6.8.0/21252.6.8.1 to 252.6.15.254252.6.15.2552,046
195252.6.16.0/21252.6.16.1 to 252.6.23.254252.6.23.2552,046
196252.6.24.0/21252.6.24.1 to 252.6.31.254252.6.31.2552,046
197252.6.32.0/21252.6.32.1 to 252.6.39.254252.6.39.2552,046
198252.6.40.0/21252.6.40.1 to 252.6.47.254252.6.47.2552,046
199252.6.48.0/21252.6.48.1 to 252.6.55.254252.6.55.2552,046
200252.6.56.0/21252.6.56.1 to 252.6.63.254252.6.63.2552,046
201252.6.64.0/21252.6.64.1 to 252.6.71.254252.6.71.2552,046
202252.6.72.0/21252.6.72.1 to 252.6.79.254252.6.79.2552,046
203252.6.80.0/21252.6.80.1 to 252.6.87.254252.6.87.2552,046
204252.6.88.0/21252.6.88.1 to 252.6.95.254252.6.95.2552,046
205252.6.96.0/21252.6.96.1 to 252.6.103.254252.6.103.2552,046
206252.6.104.0/21252.6.104.1 to 252.6.111.254252.6.111.2552,046
207252.6.112.0/21252.6.112.1 to 252.6.119.254252.6.119.2552,046
208252.6.120.0/21252.6.120.1 to 252.6.127.254252.6.127.2552,046
209252.6.128.0/21252.6.128.1 to 252.6.135.254252.6.135.2552,046
210252.6.136.0/21252.6.136.1 to 252.6.143.254252.6.143.2552,046
211252.6.144.0/21252.6.144.1 to 252.6.151.254252.6.151.2552,046
212252.6.152.0/21252.6.152.1 to 252.6.159.254252.6.159.2552,046
213252.6.160.0/21252.6.160.1 to 252.6.167.254252.6.167.2552,046
214252.6.168.0/21252.6.168.1 to 252.6.175.254252.6.175.2552,046
215252.6.176.0/21252.6.176.1 to 252.6.183.254252.6.183.2552,046
216252.6.184.0/21252.6.184.1 to 252.6.191.254252.6.191.2552,046
217252.6.192.0/21252.6.192.1 to 252.6.199.254252.6.199.2552,046
218252.6.200.0/21252.6.200.1 to 252.6.207.254252.6.207.2552,046
219252.6.208.0/21252.6.208.1 to 252.6.215.254252.6.215.2552,046
220252.6.216.0/21252.6.216.1 to 252.6.223.254252.6.223.2552,046
221252.6.224.0/21252.6.224.1 to 252.6.231.254252.6.231.2552,046
222252.6.232.0/21252.6.232.1 to 252.6.239.254252.6.239.2552,046
223252.6.240.0/21252.6.240.1 to 252.6.247.254252.6.247.2552,046
224252.6.248.0/21252.6.248.1 to 252.6.255.254252.6.255.2552,046
225252.7.0.0/21252.7.0.1 to 252.7.7.254252.7.7.2552,046
226252.7.8.0/21252.7.8.1 to 252.7.15.254252.7.15.2552,046
227252.7.16.0/21252.7.16.1 to 252.7.23.254252.7.23.2552,046
228252.7.24.0/21252.7.24.1 to 252.7.31.254252.7.31.2552,046
229252.7.32.0/21252.7.32.1 to 252.7.39.254252.7.39.2552,046
230252.7.40.0/21252.7.40.1 to 252.7.47.254252.7.47.2552,046
231252.7.48.0/21252.7.48.1 to 252.7.55.254252.7.55.2552,046
232252.7.56.0/21252.7.56.1 to 252.7.63.254252.7.63.2552,046
233252.7.64.0/21252.7.64.1 to 252.7.71.254252.7.71.2552,046
234252.7.72.0/21252.7.72.1 to 252.7.79.254252.7.79.2552,046
235252.7.80.0/21252.7.80.1 to 252.7.87.254252.7.87.2552,046
236252.7.88.0/21252.7.88.1 to 252.7.95.254252.7.95.2552,046
237252.7.96.0/21252.7.96.1 to 252.7.103.254252.7.103.2552,046
238252.7.104.0/21252.7.104.1 to 252.7.111.254252.7.111.2552,046
239252.7.112.0/21252.7.112.1 to 252.7.119.254252.7.119.2552,046
240252.7.120.0/21252.7.120.1 to 252.7.127.254252.7.127.2552,046
241252.7.128.0/21252.7.128.1 to 252.7.135.254252.7.135.2552,046
242252.7.136.0/21252.7.136.1 to 252.7.143.254252.7.143.2552,046
243252.7.144.0/21252.7.144.1 to 252.7.151.254252.7.151.2552,046
244252.7.152.0/21252.7.152.1 to 252.7.159.254252.7.159.2552,046
245252.7.160.0/21252.7.160.1 to 252.7.167.254252.7.167.2552,046
246252.7.168.0/21252.7.168.1 to 252.7.175.254252.7.175.2552,046
247252.7.176.0/21252.7.176.1 to 252.7.183.254252.7.183.2552,046
248252.7.184.0/21252.7.184.1 to 252.7.191.254252.7.191.2552,046
249252.7.192.0/21252.7.192.1 to 252.7.199.254252.7.199.2552,046
250252.7.200.0/21252.7.200.1 to 252.7.207.254252.7.207.2552,046
251252.7.208.0/21252.7.208.1 to 252.7.215.254252.7.215.2552,046
252252.7.216.0/21252.7.216.1 to 252.7.223.254252.7.223.2552,046
253252.7.224.0/21252.7.224.1 to 252.7.231.254252.7.231.2552,046
254252.7.232.0/21252.7.232.1 to 252.7.239.254252.7.239.2552,046
255252.7.240.0/21252.7.240.1 to 252.7.247.254252.7.247.2552,046
256252.7.248.0/21252.7.248.1 to 252.7.255.254252.7.255.2552,046

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.