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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.

Network208.136.0.0/13
Usable hosts524,286
Subnet mask255.248.0.0
Addresses524,288
Network address
208.136.0.0
Broadcast address
208.143.255.255
First usable
208.136.0.1
Last usable
208.143.255.254
Usable hosts
524,286 (524,288 less the network and broadcast addresses)
Subnet mask
255.248.0.0
Wildcard mask
0.7.255.255 (Cisco ACLs, OSPF)
Prefix length
/13
Type
Public public
Old class
C (default /24)
As numbers
Hex D0880000 · Integer 3498573824 to 3499098111
Reverse DNS zones
136.208.in-addr.arpa
137.208.in-addr.arpa
138.208.in-addr.arpa
139.208.in-addr.arpa
140.208.in-addr.arpa
141.208.in-addr.arpa
142.208.in-addr.arpa
143.208.in-addr.arpa
/13 is not on a 8-bit boundary, so it takes 8 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11010000.10001000.00000000.00000000208.136.0.0
Subnet mask11111111.11111000.00000000.00000000255.248.0.0
Network11010000.10001000.00000000.00000000208.136.0.0
Broadcast11010000.10001111.11111111.11111111208.143.255.255
Split into smaller subnets/21
/14 (2)/15 (4)/16 (8)/17 (16)/18 (32)/19 (64)/20 (128)/21 (256)/22 (512)/23 (1,024)/24 (2,048)/25 (4,096)

208.136.0.0/13 makes 256 subnets of /21.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1208.136.0.0/21208.136.0.1 to 208.136.7.254208.136.7.2552,046
2208.136.8.0/21208.136.8.1 to 208.136.15.254208.136.15.2552,046
3208.136.16.0/21208.136.16.1 to 208.136.23.254208.136.23.2552,046
4208.136.24.0/21208.136.24.1 to 208.136.31.254208.136.31.2552,046
5208.136.32.0/21208.136.32.1 to 208.136.39.254208.136.39.2552,046
6208.136.40.0/21208.136.40.1 to 208.136.47.254208.136.47.2552,046
7208.136.48.0/21208.136.48.1 to 208.136.55.254208.136.55.2552,046
8208.136.56.0/21208.136.56.1 to 208.136.63.254208.136.63.2552,046
9208.136.64.0/21208.136.64.1 to 208.136.71.254208.136.71.2552,046
10208.136.72.0/21208.136.72.1 to 208.136.79.254208.136.79.2552,046
11208.136.80.0/21208.136.80.1 to 208.136.87.254208.136.87.2552,046
12208.136.88.0/21208.136.88.1 to 208.136.95.254208.136.95.2552,046
13208.136.96.0/21208.136.96.1 to 208.136.103.254208.136.103.2552,046
14208.136.104.0/21208.136.104.1 to 208.136.111.254208.136.111.2552,046
15208.136.112.0/21208.136.112.1 to 208.136.119.254208.136.119.2552,046
16208.136.120.0/21208.136.120.1 to 208.136.127.254208.136.127.2552,046
17208.136.128.0/21208.136.128.1 to 208.136.135.254208.136.135.2552,046
18208.136.136.0/21208.136.136.1 to 208.136.143.254208.136.143.2552,046
19208.136.144.0/21208.136.144.1 to 208.136.151.254208.136.151.2552,046
20208.136.152.0/21208.136.152.1 to 208.136.159.254208.136.159.2552,046
21208.136.160.0/21208.136.160.1 to 208.136.167.254208.136.167.2552,046
22208.136.168.0/21208.136.168.1 to 208.136.175.254208.136.175.2552,046
23208.136.176.0/21208.136.176.1 to 208.136.183.254208.136.183.2552,046
24208.136.184.0/21208.136.184.1 to 208.136.191.254208.136.191.2552,046
25208.136.192.0/21208.136.192.1 to 208.136.199.254208.136.199.2552,046
26208.136.200.0/21208.136.200.1 to 208.136.207.254208.136.207.2552,046
27208.136.208.0/21208.136.208.1 to 208.136.215.254208.136.215.2552,046
28208.136.216.0/21208.136.216.1 to 208.136.223.254208.136.223.2552,046
29208.136.224.0/21208.136.224.1 to 208.136.231.254208.136.231.2552,046
30208.136.232.0/21208.136.232.1 to 208.136.239.254208.136.239.2552,046
31208.136.240.0/21208.136.240.1 to 208.136.247.254208.136.247.2552,046
32208.136.248.0/21208.136.248.1 to 208.136.255.254208.136.255.2552,046
33208.137.0.0/21208.137.0.1 to 208.137.7.254208.137.7.2552,046
34208.137.8.0/21208.137.8.1 to 208.137.15.254208.137.15.2552,046
35208.137.16.0/21208.137.16.1 to 208.137.23.254208.137.23.2552,046
36208.137.24.0/21208.137.24.1 to 208.137.31.254208.137.31.2552,046
37208.137.32.0/21208.137.32.1 to 208.137.39.254208.137.39.2552,046
38208.137.40.0/21208.137.40.1 to 208.137.47.254208.137.47.2552,046
39208.137.48.0/21208.137.48.1 to 208.137.55.254208.137.55.2552,046
40208.137.56.0/21208.137.56.1 to 208.137.63.254208.137.63.2552,046
41208.137.64.0/21208.137.64.1 to 208.137.71.254208.137.71.2552,046
42208.137.72.0/21208.137.72.1 to 208.137.79.254208.137.79.2552,046
43208.137.80.0/21208.137.80.1 to 208.137.87.254208.137.87.2552,046
44208.137.88.0/21208.137.88.1 to 208.137.95.254208.137.95.2552,046
45208.137.96.0/21208.137.96.1 to 208.137.103.254208.137.103.2552,046
46208.137.104.0/21208.137.104.1 to 208.137.111.254208.137.111.2552,046
47208.137.112.0/21208.137.112.1 to 208.137.119.254208.137.119.2552,046
48208.137.120.0/21208.137.120.1 to 208.137.127.254208.137.127.2552,046
49208.137.128.0/21208.137.128.1 to 208.137.135.254208.137.135.2552,046
50208.137.136.0/21208.137.136.1 to 208.137.143.254208.137.143.2552,046
51208.137.144.0/21208.137.144.1 to 208.137.151.254208.137.151.2552,046
52208.137.152.0/21208.137.152.1 to 208.137.159.254208.137.159.2552,046
53208.137.160.0/21208.137.160.1 to 208.137.167.254208.137.167.2552,046
54208.137.168.0/21208.137.168.1 to 208.137.175.254208.137.175.2552,046
55208.137.176.0/21208.137.176.1 to 208.137.183.254208.137.183.2552,046
56208.137.184.0/21208.137.184.1 to 208.137.191.254208.137.191.2552,046
57208.137.192.0/21208.137.192.1 to 208.137.199.254208.137.199.2552,046
58208.137.200.0/21208.137.200.1 to 208.137.207.254208.137.207.2552,046
59208.137.208.0/21208.137.208.1 to 208.137.215.254208.137.215.2552,046
60208.137.216.0/21208.137.216.1 to 208.137.223.254208.137.223.2552,046
61208.137.224.0/21208.137.224.1 to 208.137.231.254208.137.231.2552,046
62208.137.232.0/21208.137.232.1 to 208.137.239.254208.137.239.2552,046
63208.137.240.0/21208.137.240.1 to 208.137.247.254208.137.247.2552,046
64208.137.248.0/21208.137.248.1 to 208.137.255.254208.137.255.2552,046
65208.138.0.0/21208.138.0.1 to 208.138.7.254208.138.7.2552,046
66208.138.8.0/21208.138.8.1 to 208.138.15.254208.138.15.2552,046
67208.138.16.0/21208.138.16.1 to 208.138.23.254208.138.23.2552,046
68208.138.24.0/21208.138.24.1 to 208.138.31.254208.138.31.2552,046
69208.138.32.0/21208.138.32.1 to 208.138.39.254208.138.39.2552,046
70208.138.40.0/21208.138.40.1 to 208.138.47.254208.138.47.2552,046
71208.138.48.0/21208.138.48.1 to 208.138.55.254208.138.55.2552,046
72208.138.56.0/21208.138.56.1 to 208.138.63.254208.138.63.2552,046
73208.138.64.0/21208.138.64.1 to 208.138.71.254208.138.71.2552,046
74208.138.72.0/21208.138.72.1 to 208.138.79.254208.138.79.2552,046
75208.138.80.0/21208.138.80.1 to 208.138.87.254208.138.87.2552,046
76208.138.88.0/21208.138.88.1 to 208.138.95.254208.138.95.2552,046
77208.138.96.0/21208.138.96.1 to 208.138.103.254208.138.103.2552,046
78208.138.104.0/21208.138.104.1 to 208.138.111.254208.138.111.2552,046
79208.138.112.0/21208.138.112.1 to 208.138.119.254208.138.119.2552,046
80208.138.120.0/21208.138.120.1 to 208.138.127.254208.138.127.2552,046
81208.138.128.0/21208.138.128.1 to 208.138.135.254208.138.135.2552,046
82208.138.136.0/21208.138.136.1 to 208.138.143.254208.138.143.2552,046
83208.138.144.0/21208.138.144.1 to 208.138.151.254208.138.151.2552,046
84208.138.152.0/21208.138.152.1 to 208.138.159.254208.138.159.2552,046
85208.138.160.0/21208.138.160.1 to 208.138.167.254208.138.167.2552,046
86208.138.168.0/21208.138.168.1 to 208.138.175.254208.138.175.2552,046
87208.138.176.0/21208.138.176.1 to 208.138.183.254208.138.183.2552,046
88208.138.184.0/21208.138.184.1 to 208.138.191.254208.138.191.2552,046
89208.138.192.0/21208.138.192.1 to 208.138.199.254208.138.199.2552,046
90208.138.200.0/21208.138.200.1 to 208.138.207.254208.138.207.2552,046
91208.138.208.0/21208.138.208.1 to 208.138.215.254208.138.215.2552,046
92208.138.216.0/21208.138.216.1 to 208.138.223.254208.138.223.2552,046
93208.138.224.0/21208.138.224.1 to 208.138.231.254208.138.231.2552,046
94208.138.232.0/21208.138.232.1 to 208.138.239.254208.138.239.2552,046
95208.138.240.0/21208.138.240.1 to 208.138.247.254208.138.247.2552,046
96208.138.248.0/21208.138.248.1 to 208.138.255.254208.138.255.2552,046
97208.139.0.0/21208.139.0.1 to 208.139.7.254208.139.7.2552,046
98208.139.8.0/21208.139.8.1 to 208.139.15.254208.139.15.2552,046
99208.139.16.0/21208.139.16.1 to 208.139.23.254208.139.23.2552,046
100208.139.24.0/21208.139.24.1 to 208.139.31.254208.139.31.2552,046
101208.139.32.0/21208.139.32.1 to 208.139.39.254208.139.39.2552,046
102208.139.40.0/21208.139.40.1 to 208.139.47.254208.139.47.2552,046
103208.139.48.0/21208.139.48.1 to 208.139.55.254208.139.55.2552,046
104208.139.56.0/21208.139.56.1 to 208.139.63.254208.139.63.2552,046
105208.139.64.0/21208.139.64.1 to 208.139.71.254208.139.71.2552,046
106208.139.72.0/21208.139.72.1 to 208.139.79.254208.139.79.2552,046
107208.139.80.0/21208.139.80.1 to 208.139.87.254208.139.87.2552,046
108208.139.88.0/21208.139.88.1 to 208.139.95.254208.139.95.2552,046
109208.139.96.0/21208.139.96.1 to 208.139.103.254208.139.103.2552,046
110208.139.104.0/21208.139.104.1 to 208.139.111.254208.139.111.2552,046
111208.139.112.0/21208.139.112.1 to 208.139.119.254208.139.119.2552,046
112208.139.120.0/21208.139.120.1 to 208.139.127.254208.139.127.2552,046
113208.139.128.0/21208.139.128.1 to 208.139.135.254208.139.135.2552,046
114208.139.136.0/21208.139.136.1 to 208.139.143.254208.139.143.2552,046
115208.139.144.0/21208.139.144.1 to 208.139.151.254208.139.151.2552,046
116208.139.152.0/21208.139.152.1 to 208.139.159.254208.139.159.2552,046
117208.139.160.0/21208.139.160.1 to 208.139.167.254208.139.167.2552,046
118208.139.168.0/21208.139.168.1 to 208.139.175.254208.139.175.2552,046
119208.139.176.0/21208.139.176.1 to 208.139.183.254208.139.183.2552,046
120208.139.184.0/21208.139.184.1 to 208.139.191.254208.139.191.2552,046
121208.139.192.0/21208.139.192.1 to 208.139.199.254208.139.199.2552,046
122208.139.200.0/21208.139.200.1 to 208.139.207.254208.139.207.2552,046
123208.139.208.0/21208.139.208.1 to 208.139.215.254208.139.215.2552,046
124208.139.216.0/21208.139.216.1 to 208.139.223.254208.139.223.2552,046
125208.139.224.0/21208.139.224.1 to 208.139.231.254208.139.231.2552,046
126208.139.232.0/21208.139.232.1 to 208.139.239.254208.139.239.2552,046
127208.139.240.0/21208.139.240.1 to 208.139.247.254208.139.247.2552,046
128208.139.248.0/21208.139.248.1 to 208.139.255.254208.139.255.2552,046
129208.140.0.0/21208.140.0.1 to 208.140.7.254208.140.7.2552,046
130208.140.8.0/21208.140.8.1 to 208.140.15.254208.140.15.2552,046
131208.140.16.0/21208.140.16.1 to 208.140.23.254208.140.23.2552,046
132208.140.24.0/21208.140.24.1 to 208.140.31.254208.140.31.2552,046
133208.140.32.0/21208.140.32.1 to 208.140.39.254208.140.39.2552,046
134208.140.40.0/21208.140.40.1 to 208.140.47.254208.140.47.2552,046
135208.140.48.0/21208.140.48.1 to 208.140.55.254208.140.55.2552,046
136208.140.56.0/21208.140.56.1 to 208.140.63.254208.140.63.2552,046
137208.140.64.0/21208.140.64.1 to 208.140.71.254208.140.71.2552,046
138208.140.72.0/21208.140.72.1 to 208.140.79.254208.140.79.2552,046
139208.140.80.0/21208.140.80.1 to 208.140.87.254208.140.87.2552,046
140208.140.88.0/21208.140.88.1 to 208.140.95.254208.140.95.2552,046
141208.140.96.0/21208.140.96.1 to 208.140.103.254208.140.103.2552,046
142208.140.104.0/21208.140.104.1 to 208.140.111.254208.140.111.2552,046
143208.140.112.0/21208.140.112.1 to 208.140.119.254208.140.119.2552,046
144208.140.120.0/21208.140.120.1 to 208.140.127.254208.140.127.2552,046
145208.140.128.0/21208.140.128.1 to 208.140.135.254208.140.135.2552,046
146208.140.136.0/21208.140.136.1 to 208.140.143.254208.140.143.2552,046
147208.140.144.0/21208.140.144.1 to 208.140.151.254208.140.151.2552,046
148208.140.152.0/21208.140.152.1 to 208.140.159.254208.140.159.2552,046
149208.140.160.0/21208.140.160.1 to 208.140.167.254208.140.167.2552,046
150208.140.168.0/21208.140.168.1 to 208.140.175.254208.140.175.2552,046
151208.140.176.0/21208.140.176.1 to 208.140.183.254208.140.183.2552,046
152208.140.184.0/21208.140.184.1 to 208.140.191.254208.140.191.2552,046
153208.140.192.0/21208.140.192.1 to 208.140.199.254208.140.199.2552,046
154208.140.200.0/21208.140.200.1 to 208.140.207.254208.140.207.2552,046
155208.140.208.0/21208.140.208.1 to 208.140.215.254208.140.215.2552,046
156208.140.216.0/21208.140.216.1 to 208.140.223.254208.140.223.2552,046
157208.140.224.0/21208.140.224.1 to 208.140.231.254208.140.231.2552,046
158208.140.232.0/21208.140.232.1 to 208.140.239.254208.140.239.2552,046
159208.140.240.0/21208.140.240.1 to 208.140.247.254208.140.247.2552,046
160208.140.248.0/21208.140.248.1 to 208.140.255.254208.140.255.2552,046
161208.141.0.0/21208.141.0.1 to 208.141.7.254208.141.7.2552,046
162208.141.8.0/21208.141.8.1 to 208.141.15.254208.141.15.2552,046
163208.141.16.0/21208.141.16.1 to 208.141.23.254208.141.23.2552,046
164208.141.24.0/21208.141.24.1 to 208.141.31.254208.141.31.2552,046
165208.141.32.0/21208.141.32.1 to 208.141.39.254208.141.39.2552,046
166208.141.40.0/21208.141.40.1 to 208.141.47.254208.141.47.2552,046
167208.141.48.0/21208.141.48.1 to 208.141.55.254208.141.55.2552,046
168208.141.56.0/21208.141.56.1 to 208.141.63.254208.141.63.2552,046
169208.141.64.0/21208.141.64.1 to 208.141.71.254208.141.71.2552,046
170208.141.72.0/21208.141.72.1 to 208.141.79.254208.141.79.2552,046
171208.141.80.0/21208.141.80.1 to 208.141.87.254208.141.87.2552,046
172208.141.88.0/21208.141.88.1 to 208.141.95.254208.141.95.2552,046
173208.141.96.0/21208.141.96.1 to 208.141.103.254208.141.103.2552,046
174208.141.104.0/21208.141.104.1 to 208.141.111.254208.141.111.2552,046
175208.141.112.0/21208.141.112.1 to 208.141.119.254208.141.119.2552,046
176208.141.120.0/21208.141.120.1 to 208.141.127.254208.141.127.2552,046
177208.141.128.0/21208.141.128.1 to 208.141.135.254208.141.135.2552,046
178208.141.136.0/21208.141.136.1 to 208.141.143.254208.141.143.2552,046
179208.141.144.0/21208.141.144.1 to 208.141.151.254208.141.151.2552,046
180208.141.152.0/21208.141.152.1 to 208.141.159.254208.141.159.2552,046
181208.141.160.0/21208.141.160.1 to 208.141.167.254208.141.167.2552,046
182208.141.168.0/21208.141.168.1 to 208.141.175.254208.141.175.2552,046
183208.141.176.0/21208.141.176.1 to 208.141.183.254208.141.183.2552,046
184208.141.184.0/21208.141.184.1 to 208.141.191.254208.141.191.2552,046
185208.141.192.0/21208.141.192.1 to 208.141.199.254208.141.199.2552,046
186208.141.200.0/21208.141.200.1 to 208.141.207.254208.141.207.2552,046
187208.141.208.0/21208.141.208.1 to 208.141.215.254208.141.215.2552,046
188208.141.216.0/21208.141.216.1 to 208.141.223.254208.141.223.2552,046
189208.141.224.0/21208.141.224.1 to 208.141.231.254208.141.231.2552,046
190208.141.232.0/21208.141.232.1 to 208.141.239.254208.141.239.2552,046
191208.141.240.0/21208.141.240.1 to 208.141.247.254208.141.247.2552,046
192208.141.248.0/21208.141.248.1 to 208.141.255.254208.141.255.2552,046
193208.142.0.0/21208.142.0.1 to 208.142.7.254208.142.7.2552,046
194208.142.8.0/21208.142.8.1 to 208.142.15.254208.142.15.2552,046
195208.142.16.0/21208.142.16.1 to 208.142.23.254208.142.23.2552,046
196208.142.24.0/21208.142.24.1 to 208.142.31.254208.142.31.2552,046
197208.142.32.0/21208.142.32.1 to 208.142.39.254208.142.39.2552,046
198208.142.40.0/21208.142.40.1 to 208.142.47.254208.142.47.2552,046
199208.142.48.0/21208.142.48.1 to 208.142.55.254208.142.55.2552,046
200208.142.56.0/21208.142.56.1 to 208.142.63.254208.142.63.2552,046
201208.142.64.0/21208.142.64.1 to 208.142.71.254208.142.71.2552,046
202208.142.72.0/21208.142.72.1 to 208.142.79.254208.142.79.2552,046
203208.142.80.0/21208.142.80.1 to 208.142.87.254208.142.87.2552,046
204208.142.88.0/21208.142.88.1 to 208.142.95.254208.142.95.2552,046
205208.142.96.0/21208.142.96.1 to 208.142.103.254208.142.103.2552,046
206208.142.104.0/21208.142.104.1 to 208.142.111.254208.142.111.2552,046
207208.142.112.0/21208.142.112.1 to 208.142.119.254208.142.119.2552,046
208208.142.120.0/21208.142.120.1 to 208.142.127.254208.142.127.2552,046
209208.142.128.0/21208.142.128.1 to 208.142.135.254208.142.135.2552,046
210208.142.136.0/21208.142.136.1 to 208.142.143.254208.142.143.2552,046
211208.142.144.0/21208.142.144.1 to 208.142.151.254208.142.151.2552,046
212208.142.152.0/21208.142.152.1 to 208.142.159.254208.142.159.2552,046
213208.142.160.0/21208.142.160.1 to 208.142.167.254208.142.167.2552,046
214208.142.168.0/21208.142.168.1 to 208.142.175.254208.142.175.2552,046
215208.142.176.0/21208.142.176.1 to 208.142.183.254208.142.183.2552,046
216208.142.184.0/21208.142.184.1 to 208.142.191.254208.142.191.2552,046
217208.142.192.0/21208.142.192.1 to 208.142.199.254208.142.199.2552,046
218208.142.200.0/21208.142.200.1 to 208.142.207.254208.142.207.2552,046
219208.142.208.0/21208.142.208.1 to 208.142.215.254208.142.215.2552,046
220208.142.216.0/21208.142.216.1 to 208.142.223.254208.142.223.2552,046
221208.142.224.0/21208.142.224.1 to 208.142.231.254208.142.231.2552,046
222208.142.232.0/21208.142.232.1 to 208.142.239.254208.142.239.2552,046
223208.142.240.0/21208.142.240.1 to 208.142.247.254208.142.247.2552,046
224208.142.248.0/21208.142.248.1 to 208.142.255.254208.142.255.2552,046
225208.143.0.0/21208.143.0.1 to 208.143.7.254208.143.7.2552,046
226208.143.8.0/21208.143.8.1 to 208.143.15.254208.143.15.2552,046
227208.143.16.0/21208.143.16.1 to 208.143.23.254208.143.23.2552,046
228208.143.24.0/21208.143.24.1 to 208.143.31.254208.143.31.2552,046
229208.143.32.0/21208.143.32.1 to 208.143.39.254208.143.39.2552,046
230208.143.40.0/21208.143.40.1 to 208.143.47.254208.143.47.2552,046
231208.143.48.0/21208.143.48.1 to 208.143.55.254208.143.55.2552,046
232208.143.56.0/21208.143.56.1 to 208.143.63.254208.143.63.2552,046
233208.143.64.0/21208.143.64.1 to 208.143.71.254208.143.71.2552,046
234208.143.72.0/21208.143.72.1 to 208.143.79.254208.143.79.2552,046
235208.143.80.0/21208.143.80.1 to 208.143.87.254208.143.87.2552,046
236208.143.88.0/21208.143.88.1 to 208.143.95.254208.143.95.2552,046
237208.143.96.0/21208.143.96.1 to 208.143.103.254208.143.103.2552,046
238208.143.104.0/21208.143.104.1 to 208.143.111.254208.143.111.2552,046
239208.143.112.0/21208.143.112.1 to 208.143.119.254208.143.119.2552,046
240208.143.120.0/21208.143.120.1 to 208.143.127.254208.143.127.2552,046
241208.143.128.0/21208.143.128.1 to 208.143.135.254208.143.135.2552,046
242208.143.136.0/21208.143.136.1 to 208.143.143.254208.143.143.2552,046
243208.143.144.0/21208.143.144.1 to 208.143.151.254208.143.151.2552,046
244208.143.152.0/21208.143.152.1 to 208.143.159.254208.143.159.2552,046
245208.143.160.0/21208.143.160.1 to 208.143.167.254208.143.167.2552,046
246208.143.168.0/21208.143.168.1 to 208.143.175.254208.143.175.2552,046
247208.143.176.0/21208.143.176.1 to 208.143.183.254208.143.183.2552,046
248208.143.184.0/21208.143.184.1 to 208.143.191.254208.143.191.2552,046
249208.143.192.0/21208.143.192.1 to 208.143.199.254208.143.199.2552,046
250208.143.200.0/21208.143.200.1 to 208.143.207.254208.143.207.2552,046
251208.143.208.0/21208.143.208.1 to 208.143.215.254208.143.215.2552,046
252208.143.216.0/21208.143.216.1 to 208.143.223.254208.143.223.2552,046
253208.143.224.0/21208.143.224.1 to 208.143.231.254208.143.231.2552,046
254208.143.232.0/21208.143.232.1 to 208.143.239.254208.143.239.2552,046
255208.143.240.0/21208.143.240.1 to 208.143.247.254208.143.247.2552,046
256208.143.248.0/21208.143.248.1 to 208.143.255.254208.143.255.2552,046

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.