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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.

Network247.136.0.0/13
Usable hosts524,286
Subnet mask255.248.0.0
Addresses524,288
Network address
247.136.0.0
Broadcast address
247.143.255.255
First usable
247.136.0.1
Last usable
247.143.255.254
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
Reserved 240.0.0.0/4
Future use; not usable on most systems
Old class
E (reserved)
As numbers
Hex F7880000 · Integer 4152885248 to 4153409535
Reverse DNS zones
136.247.in-addr.arpa
137.247.in-addr.arpa
138.247.in-addr.arpa
139.247.in-addr.arpa
140.247.in-addr.arpa
141.247.in-addr.arpa
142.247.in-addr.arpa
143.247.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
Address11110111.10001000.00000000.00000000247.136.0.0
Subnet mask11111111.11111000.00000000.00000000255.248.0.0
Network11110111.10001000.00000000.00000000247.136.0.0
Broadcast11110111.10001111.11111111.11111111247.143.255.255
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)

247.136.0.0/13 makes 256 subnets of /21.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1247.136.0.0/21247.136.0.1 to 247.136.7.254247.136.7.2552,046
2247.136.8.0/21247.136.8.1 to 247.136.15.254247.136.15.2552,046
3247.136.16.0/21247.136.16.1 to 247.136.23.254247.136.23.2552,046
4247.136.24.0/21247.136.24.1 to 247.136.31.254247.136.31.2552,046
5247.136.32.0/21247.136.32.1 to 247.136.39.254247.136.39.2552,046
6247.136.40.0/21247.136.40.1 to 247.136.47.254247.136.47.2552,046
7247.136.48.0/21247.136.48.1 to 247.136.55.254247.136.55.2552,046
8247.136.56.0/21247.136.56.1 to 247.136.63.254247.136.63.2552,046
9247.136.64.0/21247.136.64.1 to 247.136.71.254247.136.71.2552,046
10247.136.72.0/21247.136.72.1 to 247.136.79.254247.136.79.2552,046
11247.136.80.0/21247.136.80.1 to 247.136.87.254247.136.87.2552,046
12247.136.88.0/21247.136.88.1 to 247.136.95.254247.136.95.2552,046
13247.136.96.0/21247.136.96.1 to 247.136.103.254247.136.103.2552,046
14247.136.104.0/21247.136.104.1 to 247.136.111.254247.136.111.2552,046
15247.136.112.0/21247.136.112.1 to 247.136.119.254247.136.119.2552,046
16247.136.120.0/21247.136.120.1 to 247.136.127.254247.136.127.2552,046
17247.136.128.0/21247.136.128.1 to 247.136.135.254247.136.135.2552,046
18247.136.136.0/21247.136.136.1 to 247.136.143.254247.136.143.2552,046
19247.136.144.0/21247.136.144.1 to 247.136.151.254247.136.151.2552,046
20247.136.152.0/21247.136.152.1 to 247.136.159.254247.136.159.2552,046
21247.136.160.0/21247.136.160.1 to 247.136.167.254247.136.167.2552,046
22247.136.168.0/21247.136.168.1 to 247.136.175.254247.136.175.2552,046
23247.136.176.0/21247.136.176.1 to 247.136.183.254247.136.183.2552,046
24247.136.184.0/21247.136.184.1 to 247.136.191.254247.136.191.2552,046
25247.136.192.0/21247.136.192.1 to 247.136.199.254247.136.199.2552,046
26247.136.200.0/21247.136.200.1 to 247.136.207.254247.136.207.2552,046
27247.136.208.0/21247.136.208.1 to 247.136.215.254247.136.215.2552,046
28247.136.216.0/21247.136.216.1 to 247.136.223.254247.136.223.2552,046
29247.136.224.0/21247.136.224.1 to 247.136.231.254247.136.231.2552,046
30247.136.232.0/21247.136.232.1 to 247.136.239.254247.136.239.2552,046
31247.136.240.0/21247.136.240.1 to 247.136.247.254247.136.247.2552,046
32247.136.248.0/21247.136.248.1 to 247.136.255.254247.136.255.2552,046
33247.137.0.0/21247.137.0.1 to 247.137.7.254247.137.7.2552,046
34247.137.8.0/21247.137.8.1 to 247.137.15.254247.137.15.2552,046
35247.137.16.0/21247.137.16.1 to 247.137.23.254247.137.23.2552,046
36247.137.24.0/21247.137.24.1 to 247.137.31.254247.137.31.2552,046
37247.137.32.0/21247.137.32.1 to 247.137.39.254247.137.39.2552,046
38247.137.40.0/21247.137.40.1 to 247.137.47.254247.137.47.2552,046
39247.137.48.0/21247.137.48.1 to 247.137.55.254247.137.55.2552,046
40247.137.56.0/21247.137.56.1 to 247.137.63.254247.137.63.2552,046
41247.137.64.0/21247.137.64.1 to 247.137.71.254247.137.71.2552,046
42247.137.72.0/21247.137.72.1 to 247.137.79.254247.137.79.2552,046
43247.137.80.0/21247.137.80.1 to 247.137.87.254247.137.87.2552,046
44247.137.88.0/21247.137.88.1 to 247.137.95.254247.137.95.2552,046
45247.137.96.0/21247.137.96.1 to 247.137.103.254247.137.103.2552,046
46247.137.104.0/21247.137.104.1 to 247.137.111.254247.137.111.2552,046
47247.137.112.0/21247.137.112.1 to 247.137.119.254247.137.119.2552,046
48247.137.120.0/21247.137.120.1 to 247.137.127.254247.137.127.2552,046
49247.137.128.0/21247.137.128.1 to 247.137.135.254247.137.135.2552,046
50247.137.136.0/21247.137.136.1 to 247.137.143.254247.137.143.2552,046
51247.137.144.0/21247.137.144.1 to 247.137.151.254247.137.151.2552,046
52247.137.152.0/21247.137.152.1 to 247.137.159.254247.137.159.2552,046
53247.137.160.0/21247.137.160.1 to 247.137.167.254247.137.167.2552,046
54247.137.168.0/21247.137.168.1 to 247.137.175.254247.137.175.2552,046
55247.137.176.0/21247.137.176.1 to 247.137.183.254247.137.183.2552,046
56247.137.184.0/21247.137.184.1 to 247.137.191.254247.137.191.2552,046
57247.137.192.0/21247.137.192.1 to 247.137.199.254247.137.199.2552,046
58247.137.200.0/21247.137.200.1 to 247.137.207.254247.137.207.2552,046
59247.137.208.0/21247.137.208.1 to 247.137.215.254247.137.215.2552,046
60247.137.216.0/21247.137.216.1 to 247.137.223.254247.137.223.2552,046
61247.137.224.0/21247.137.224.1 to 247.137.231.254247.137.231.2552,046
62247.137.232.0/21247.137.232.1 to 247.137.239.254247.137.239.2552,046
63247.137.240.0/21247.137.240.1 to 247.137.247.254247.137.247.2552,046
64247.137.248.0/21247.137.248.1 to 247.137.255.254247.137.255.2552,046
65247.138.0.0/21247.138.0.1 to 247.138.7.254247.138.7.2552,046
66247.138.8.0/21247.138.8.1 to 247.138.15.254247.138.15.2552,046
67247.138.16.0/21247.138.16.1 to 247.138.23.254247.138.23.2552,046
68247.138.24.0/21247.138.24.1 to 247.138.31.254247.138.31.2552,046
69247.138.32.0/21247.138.32.1 to 247.138.39.254247.138.39.2552,046
70247.138.40.0/21247.138.40.1 to 247.138.47.254247.138.47.2552,046
71247.138.48.0/21247.138.48.1 to 247.138.55.254247.138.55.2552,046
72247.138.56.0/21247.138.56.1 to 247.138.63.254247.138.63.2552,046
73247.138.64.0/21247.138.64.1 to 247.138.71.254247.138.71.2552,046
74247.138.72.0/21247.138.72.1 to 247.138.79.254247.138.79.2552,046
75247.138.80.0/21247.138.80.1 to 247.138.87.254247.138.87.2552,046
76247.138.88.0/21247.138.88.1 to 247.138.95.254247.138.95.2552,046
77247.138.96.0/21247.138.96.1 to 247.138.103.254247.138.103.2552,046
78247.138.104.0/21247.138.104.1 to 247.138.111.254247.138.111.2552,046
79247.138.112.0/21247.138.112.1 to 247.138.119.254247.138.119.2552,046
80247.138.120.0/21247.138.120.1 to 247.138.127.254247.138.127.2552,046
81247.138.128.0/21247.138.128.1 to 247.138.135.254247.138.135.2552,046
82247.138.136.0/21247.138.136.1 to 247.138.143.254247.138.143.2552,046
83247.138.144.0/21247.138.144.1 to 247.138.151.254247.138.151.2552,046
84247.138.152.0/21247.138.152.1 to 247.138.159.254247.138.159.2552,046
85247.138.160.0/21247.138.160.1 to 247.138.167.254247.138.167.2552,046
86247.138.168.0/21247.138.168.1 to 247.138.175.254247.138.175.2552,046
87247.138.176.0/21247.138.176.1 to 247.138.183.254247.138.183.2552,046
88247.138.184.0/21247.138.184.1 to 247.138.191.254247.138.191.2552,046
89247.138.192.0/21247.138.192.1 to 247.138.199.254247.138.199.2552,046
90247.138.200.0/21247.138.200.1 to 247.138.207.254247.138.207.2552,046
91247.138.208.0/21247.138.208.1 to 247.138.215.254247.138.215.2552,046
92247.138.216.0/21247.138.216.1 to 247.138.223.254247.138.223.2552,046
93247.138.224.0/21247.138.224.1 to 247.138.231.254247.138.231.2552,046
94247.138.232.0/21247.138.232.1 to 247.138.239.254247.138.239.2552,046
95247.138.240.0/21247.138.240.1 to 247.138.247.254247.138.247.2552,046
96247.138.248.0/21247.138.248.1 to 247.138.255.254247.138.255.2552,046
97247.139.0.0/21247.139.0.1 to 247.139.7.254247.139.7.2552,046
98247.139.8.0/21247.139.8.1 to 247.139.15.254247.139.15.2552,046
99247.139.16.0/21247.139.16.1 to 247.139.23.254247.139.23.2552,046
100247.139.24.0/21247.139.24.1 to 247.139.31.254247.139.31.2552,046
101247.139.32.0/21247.139.32.1 to 247.139.39.254247.139.39.2552,046
102247.139.40.0/21247.139.40.1 to 247.139.47.254247.139.47.2552,046
103247.139.48.0/21247.139.48.1 to 247.139.55.254247.139.55.2552,046
104247.139.56.0/21247.139.56.1 to 247.139.63.254247.139.63.2552,046
105247.139.64.0/21247.139.64.1 to 247.139.71.254247.139.71.2552,046
106247.139.72.0/21247.139.72.1 to 247.139.79.254247.139.79.2552,046
107247.139.80.0/21247.139.80.1 to 247.139.87.254247.139.87.2552,046
108247.139.88.0/21247.139.88.1 to 247.139.95.254247.139.95.2552,046
109247.139.96.0/21247.139.96.1 to 247.139.103.254247.139.103.2552,046
110247.139.104.0/21247.139.104.1 to 247.139.111.254247.139.111.2552,046
111247.139.112.0/21247.139.112.1 to 247.139.119.254247.139.119.2552,046
112247.139.120.0/21247.139.120.1 to 247.139.127.254247.139.127.2552,046
113247.139.128.0/21247.139.128.1 to 247.139.135.254247.139.135.2552,046
114247.139.136.0/21247.139.136.1 to 247.139.143.254247.139.143.2552,046
115247.139.144.0/21247.139.144.1 to 247.139.151.254247.139.151.2552,046
116247.139.152.0/21247.139.152.1 to 247.139.159.254247.139.159.2552,046
117247.139.160.0/21247.139.160.1 to 247.139.167.254247.139.167.2552,046
118247.139.168.0/21247.139.168.1 to 247.139.175.254247.139.175.2552,046
119247.139.176.0/21247.139.176.1 to 247.139.183.254247.139.183.2552,046
120247.139.184.0/21247.139.184.1 to 247.139.191.254247.139.191.2552,046
121247.139.192.0/21247.139.192.1 to 247.139.199.254247.139.199.2552,046
122247.139.200.0/21247.139.200.1 to 247.139.207.254247.139.207.2552,046
123247.139.208.0/21247.139.208.1 to 247.139.215.254247.139.215.2552,046
124247.139.216.0/21247.139.216.1 to 247.139.223.254247.139.223.2552,046
125247.139.224.0/21247.139.224.1 to 247.139.231.254247.139.231.2552,046
126247.139.232.0/21247.139.232.1 to 247.139.239.254247.139.239.2552,046
127247.139.240.0/21247.139.240.1 to 247.139.247.254247.139.247.2552,046
128247.139.248.0/21247.139.248.1 to 247.139.255.254247.139.255.2552,046
129247.140.0.0/21247.140.0.1 to 247.140.7.254247.140.7.2552,046
130247.140.8.0/21247.140.8.1 to 247.140.15.254247.140.15.2552,046
131247.140.16.0/21247.140.16.1 to 247.140.23.254247.140.23.2552,046
132247.140.24.0/21247.140.24.1 to 247.140.31.254247.140.31.2552,046
133247.140.32.0/21247.140.32.1 to 247.140.39.254247.140.39.2552,046
134247.140.40.0/21247.140.40.1 to 247.140.47.254247.140.47.2552,046
135247.140.48.0/21247.140.48.1 to 247.140.55.254247.140.55.2552,046
136247.140.56.0/21247.140.56.1 to 247.140.63.254247.140.63.2552,046
137247.140.64.0/21247.140.64.1 to 247.140.71.254247.140.71.2552,046
138247.140.72.0/21247.140.72.1 to 247.140.79.254247.140.79.2552,046
139247.140.80.0/21247.140.80.1 to 247.140.87.254247.140.87.2552,046
140247.140.88.0/21247.140.88.1 to 247.140.95.254247.140.95.2552,046
141247.140.96.0/21247.140.96.1 to 247.140.103.254247.140.103.2552,046
142247.140.104.0/21247.140.104.1 to 247.140.111.254247.140.111.2552,046
143247.140.112.0/21247.140.112.1 to 247.140.119.254247.140.119.2552,046
144247.140.120.0/21247.140.120.1 to 247.140.127.254247.140.127.2552,046
145247.140.128.0/21247.140.128.1 to 247.140.135.254247.140.135.2552,046
146247.140.136.0/21247.140.136.1 to 247.140.143.254247.140.143.2552,046
147247.140.144.0/21247.140.144.1 to 247.140.151.254247.140.151.2552,046
148247.140.152.0/21247.140.152.1 to 247.140.159.254247.140.159.2552,046
149247.140.160.0/21247.140.160.1 to 247.140.167.254247.140.167.2552,046
150247.140.168.0/21247.140.168.1 to 247.140.175.254247.140.175.2552,046
151247.140.176.0/21247.140.176.1 to 247.140.183.254247.140.183.2552,046
152247.140.184.0/21247.140.184.1 to 247.140.191.254247.140.191.2552,046
153247.140.192.0/21247.140.192.1 to 247.140.199.254247.140.199.2552,046
154247.140.200.0/21247.140.200.1 to 247.140.207.254247.140.207.2552,046
155247.140.208.0/21247.140.208.1 to 247.140.215.254247.140.215.2552,046
156247.140.216.0/21247.140.216.1 to 247.140.223.254247.140.223.2552,046
157247.140.224.0/21247.140.224.1 to 247.140.231.254247.140.231.2552,046
158247.140.232.0/21247.140.232.1 to 247.140.239.254247.140.239.2552,046
159247.140.240.0/21247.140.240.1 to 247.140.247.254247.140.247.2552,046
160247.140.248.0/21247.140.248.1 to 247.140.255.254247.140.255.2552,046
161247.141.0.0/21247.141.0.1 to 247.141.7.254247.141.7.2552,046
162247.141.8.0/21247.141.8.1 to 247.141.15.254247.141.15.2552,046
163247.141.16.0/21247.141.16.1 to 247.141.23.254247.141.23.2552,046
164247.141.24.0/21247.141.24.1 to 247.141.31.254247.141.31.2552,046
165247.141.32.0/21247.141.32.1 to 247.141.39.254247.141.39.2552,046
166247.141.40.0/21247.141.40.1 to 247.141.47.254247.141.47.2552,046
167247.141.48.0/21247.141.48.1 to 247.141.55.254247.141.55.2552,046
168247.141.56.0/21247.141.56.1 to 247.141.63.254247.141.63.2552,046
169247.141.64.0/21247.141.64.1 to 247.141.71.254247.141.71.2552,046
170247.141.72.0/21247.141.72.1 to 247.141.79.254247.141.79.2552,046
171247.141.80.0/21247.141.80.1 to 247.141.87.254247.141.87.2552,046
172247.141.88.0/21247.141.88.1 to 247.141.95.254247.141.95.2552,046
173247.141.96.0/21247.141.96.1 to 247.141.103.254247.141.103.2552,046
174247.141.104.0/21247.141.104.1 to 247.141.111.254247.141.111.2552,046
175247.141.112.0/21247.141.112.1 to 247.141.119.254247.141.119.2552,046
176247.141.120.0/21247.141.120.1 to 247.141.127.254247.141.127.2552,046
177247.141.128.0/21247.141.128.1 to 247.141.135.254247.141.135.2552,046
178247.141.136.0/21247.141.136.1 to 247.141.143.254247.141.143.2552,046
179247.141.144.0/21247.141.144.1 to 247.141.151.254247.141.151.2552,046
180247.141.152.0/21247.141.152.1 to 247.141.159.254247.141.159.2552,046
181247.141.160.0/21247.141.160.1 to 247.141.167.254247.141.167.2552,046
182247.141.168.0/21247.141.168.1 to 247.141.175.254247.141.175.2552,046
183247.141.176.0/21247.141.176.1 to 247.141.183.254247.141.183.2552,046
184247.141.184.0/21247.141.184.1 to 247.141.191.254247.141.191.2552,046
185247.141.192.0/21247.141.192.1 to 247.141.199.254247.141.199.2552,046
186247.141.200.0/21247.141.200.1 to 247.141.207.254247.141.207.2552,046
187247.141.208.0/21247.141.208.1 to 247.141.215.254247.141.215.2552,046
188247.141.216.0/21247.141.216.1 to 247.141.223.254247.141.223.2552,046
189247.141.224.0/21247.141.224.1 to 247.141.231.254247.141.231.2552,046
190247.141.232.0/21247.141.232.1 to 247.141.239.254247.141.239.2552,046
191247.141.240.0/21247.141.240.1 to 247.141.247.254247.141.247.2552,046
192247.141.248.0/21247.141.248.1 to 247.141.255.254247.141.255.2552,046
193247.142.0.0/21247.142.0.1 to 247.142.7.254247.142.7.2552,046
194247.142.8.0/21247.142.8.1 to 247.142.15.254247.142.15.2552,046
195247.142.16.0/21247.142.16.1 to 247.142.23.254247.142.23.2552,046
196247.142.24.0/21247.142.24.1 to 247.142.31.254247.142.31.2552,046
197247.142.32.0/21247.142.32.1 to 247.142.39.254247.142.39.2552,046
198247.142.40.0/21247.142.40.1 to 247.142.47.254247.142.47.2552,046
199247.142.48.0/21247.142.48.1 to 247.142.55.254247.142.55.2552,046
200247.142.56.0/21247.142.56.1 to 247.142.63.254247.142.63.2552,046
201247.142.64.0/21247.142.64.1 to 247.142.71.254247.142.71.2552,046
202247.142.72.0/21247.142.72.1 to 247.142.79.254247.142.79.2552,046
203247.142.80.0/21247.142.80.1 to 247.142.87.254247.142.87.2552,046
204247.142.88.0/21247.142.88.1 to 247.142.95.254247.142.95.2552,046
205247.142.96.0/21247.142.96.1 to 247.142.103.254247.142.103.2552,046
206247.142.104.0/21247.142.104.1 to 247.142.111.254247.142.111.2552,046
207247.142.112.0/21247.142.112.1 to 247.142.119.254247.142.119.2552,046
208247.142.120.0/21247.142.120.1 to 247.142.127.254247.142.127.2552,046
209247.142.128.0/21247.142.128.1 to 247.142.135.254247.142.135.2552,046
210247.142.136.0/21247.142.136.1 to 247.142.143.254247.142.143.2552,046
211247.142.144.0/21247.142.144.1 to 247.142.151.254247.142.151.2552,046
212247.142.152.0/21247.142.152.1 to 247.142.159.254247.142.159.2552,046
213247.142.160.0/21247.142.160.1 to 247.142.167.254247.142.167.2552,046
214247.142.168.0/21247.142.168.1 to 247.142.175.254247.142.175.2552,046
215247.142.176.0/21247.142.176.1 to 247.142.183.254247.142.183.2552,046
216247.142.184.0/21247.142.184.1 to 247.142.191.254247.142.191.2552,046
217247.142.192.0/21247.142.192.1 to 247.142.199.254247.142.199.2552,046
218247.142.200.0/21247.142.200.1 to 247.142.207.254247.142.207.2552,046
219247.142.208.0/21247.142.208.1 to 247.142.215.254247.142.215.2552,046
220247.142.216.0/21247.142.216.1 to 247.142.223.254247.142.223.2552,046
221247.142.224.0/21247.142.224.1 to 247.142.231.254247.142.231.2552,046
222247.142.232.0/21247.142.232.1 to 247.142.239.254247.142.239.2552,046
223247.142.240.0/21247.142.240.1 to 247.142.247.254247.142.247.2552,046
224247.142.248.0/21247.142.248.1 to 247.142.255.254247.142.255.2552,046
225247.143.0.0/21247.143.0.1 to 247.143.7.254247.143.7.2552,046
226247.143.8.0/21247.143.8.1 to 247.143.15.254247.143.15.2552,046
227247.143.16.0/21247.143.16.1 to 247.143.23.254247.143.23.2552,046
228247.143.24.0/21247.143.24.1 to 247.143.31.254247.143.31.2552,046
229247.143.32.0/21247.143.32.1 to 247.143.39.254247.143.39.2552,046
230247.143.40.0/21247.143.40.1 to 247.143.47.254247.143.47.2552,046
231247.143.48.0/21247.143.48.1 to 247.143.55.254247.143.55.2552,046
232247.143.56.0/21247.143.56.1 to 247.143.63.254247.143.63.2552,046
233247.143.64.0/21247.143.64.1 to 247.143.71.254247.143.71.2552,046
234247.143.72.0/21247.143.72.1 to 247.143.79.254247.143.79.2552,046
235247.143.80.0/21247.143.80.1 to 247.143.87.254247.143.87.2552,046
236247.143.88.0/21247.143.88.1 to 247.143.95.254247.143.95.2552,046
237247.143.96.0/21247.143.96.1 to 247.143.103.254247.143.103.2552,046
238247.143.104.0/21247.143.104.1 to 247.143.111.254247.143.111.2552,046
239247.143.112.0/21247.143.112.1 to 247.143.119.254247.143.119.2552,046
240247.143.120.0/21247.143.120.1 to 247.143.127.254247.143.127.2552,046
241247.143.128.0/21247.143.128.1 to 247.143.135.254247.143.135.2552,046
242247.143.136.0/21247.143.136.1 to 247.143.143.254247.143.143.2552,046
243247.143.144.0/21247.143.144.1 to 247.143.151.254247.143.151.2552,046
244247.143.152.0/21247.143.152.1 to 247.143.159.254247.143.159.2552,046
245247.143.160.0/21247.143.160.1 to 247.143.167.254247.143.167.2552,046
246247.143.168.0/21247.143.168.1 to 247.143.175.254247.143.175.2552,046
247247.143.176.0/21247.143.176.1 to 247.143.183.254247.143.183.2552,046
248247.143.184.0/21247.143.184.1 to 247.143.191.254247.143.191.2552,046
249247.143.192.0/21247.143.192.1 to 247.143.199.254247.143.199.2552,046
250247.143.200.0/21247.143.200.1 to 247.143.207.254247.143.207.2552,046
251247.143.208.0/21247.143.208.1 to 247.143.215.254247.143.215.2552,046
252247.143.216.0/21247.143.216.1 to 247.143.223.254247.143.223.2552,046
253247.143.224.0/21247.143.224.1 to 247.143.231.254247.143.231.2552,046
254247.143.232.0/21247.143.232.1 to 247.143.239.254247.143.239.2552,046
255247.143.240.0/21247.143.240.1 to 247.143.247.254247.143.247.2552,046
256247.143.248.0/21247.143.248.1 to 247.143.255.254247.143.255.2552,046

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.