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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.

Network187.24.0.0/13
Usable hosts524,286
Subnet mask255.248.0.0
Addresses524,288
Network address
187.24.0.0
Broadcast address
187.31.255.255
First usable
187.24.0.1
Last usable
187.31.255.254
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
B (default /16)
As numbers
Hex BB180000 · Integer 3138912256 to 3139436543
Reverse DNS zones
24.187.in-addr.arpa
25.187.in-addr.arpa
26.187.in-addr.arpa
27.187.in-addr.arpa
28.187.in-addr.arpa
29.187.in-addr.arpa
30.187.in-addr.arpa
31.187.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
Address10111011.00011000.00000000.00000000187.24.0.0
Subnet mask11111111.11111000.00000000.00000000255.248.0.0
Network10111011.00011000.00000000.00000000187.24.0.0
Broadcast10111011.00011111.11111111.11111111187.31.255.255
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)

187.24.0.0/13 makes 256 subnets of /21.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1187.24.0.0/21187.24.0.1 to 187.24.7.254187.24.7.2552,046
2187.24.8.0/21187.24.8.1 to 187.24.15.254187.24.15.2552,046
3187.24.16.0/21187.24.16.1 to 187.24.23.254187.24.23.2552,046
4187.24.24.0/21187.24.24.1 to 187.24.31.254187.24.31.2552,046
5187.24.32.0/21187.24.32.1 to 187.24.39.254187.24.39.2552,046
6187.24.40.0/21187.24.40.1 to 187.24.47.254187.24.47.2552,046
7187.24.48.0/21187.24.48.1 to 187.24.55.254187.24.55.2552,046
8187.24.56.0/21187.24.56.1 to 187.24.63.254187.24.63.2552,046
9187.24.64.0/21187.24.64.1 to 187.24.71.254187.24.71.2552,046
10187.24.72.0/21187.24.72.1 to 187.24.79.254187.24.79.2552,046
11187.24.80.0/21187.24.80.1 to 187.24.87.254187.24.87.2552,046
12187.24.88.0/21187.24.88.1 to 187.24.95.254187.24.95.2552,046
13187.24.96.0/21187.24.96.1 to 187.24.103.254187.24.103.2552,046
14187.24.104.0/21187.24.104.1 to 187.24.111.254187.24.111.2552,046
15187.24.112.0/21187.24.112.1 to 187.24.119.254187.24.119.2552,046
16187.24.120.0/21187.24.120.1 to 187.24.127.254187.24.127.2552,046
17187.24.128.0/21187.24.128.1 to 187.24.135.254187.24.135.2552,046
18187.24.136.0/21187.24.136.1 to 187.24.143.254187.24.143.2552,046
19187.24.144.0/21187.24.144.1 to 187.24.151.254187.24.151.2552,046
20187.24.152.0/21187.24.152.1 to 187.24.159.254187.24.159.2552,046
21187.24.160.0/21187.24.160.1 to 187.24.167.254187.24.167.2552,046
22187.24.168.0/21187.24.168.1 to 187.24.175.254187.24.175.2552,046
23187.24.176.0/21187.24.176.1 to 187.24.183.254187.24.183.2552,046
24187.24.184.0/21187.24.184.1 to 187.24.191.254187.24.191.2552,046
25187.24.192.0/21187.24.192.1 to 187.24.199.254187.24.199.2552,046
26187.24.200.0/21187.24.200.1 to 187.24.207.254187.24.207.2552,046
27187.24.208.0/21187.24.208.1 to 187.24.215.254187.24.215.2552,046
28187.24.216.0/21187.24.216.1 to 187.24.223.254187.24.223.2552,046
29187.24.224.0/21187.24.224.1 to 187.24.231.254187.24.231.2552,046
30187.24.232.0/21187.24.232.1 to 187.24.239.254187.24.239.2552,046
31187.24.240.0/21187.24.240.1 to 187.24.247.254187.24.247.2552,046
32187.24.248.0/21187.24.248.1 to 187.24.255.254187.24.255.2552,046
33187.25.0.0/21187.25.0.1 to 187.25.7.254187.25.7.2552,046
34187.25.8.0/21187.25.8.1 to 187.25.15.254187.25.15.2552,046
35187.25.16.0/21187.25.16.1 to 187.25.23.254187.25.23.2552,046
36187.25.24.0/21187.25.24.1 to 187.25.31.254187.25.31.2552,046
37187.25.32.0/21187.25.32.1 to 187.25.39.254187.25.39.2552,046
38187.25.40.0/21187.25.40.1 to 187.25.47.254187.25.47.2552,046
39187.25.48.0/21187.25.48.1 to 187.25.55.254187.25.55.2552,046
40187.25.56.0/21187.25.56.1 to 187.25.63.254187.25.63.2552,046
41187.25.64.0/21187.25.64.1 to 187.25.71.254187.25.71.2552,046
42187.25.72.0/21187.25.72.1 to 187.25.79.254187.25.79.2552,046
43187.25.80.0/21187.25.80.1 to 187.25.87.254187.25.87.2552,046
44187.25.88.0/21187.25.88.1 to 187.25.95.254187.25.95.2552,046
45187.25.96.0/21187.25.96.1 to 187.25.103.254187.25.103.2552,046
46187.25.104.0/21187.25.104.1 to 187.25.111.254187.25.111.2552,046
47187.25.112.0/21187.25.112.1 to 187.25.119.254187.25.119.2552,046
48187.25.120.0/21187.25.120.1 to 187.25.127.254187.25.127.2552,046
49187.25.128.0/21187.25.128.1 to 187.25.135.254187.25.135.2552,046
50187.25.136.0/21187.25.136.1 to 187.25.143.254187.25.143.2552,046
51187.25.144.0/21187.25.144.1 to 187.25.151.254187.25.151.2552,046
52187.25.152.0/21187.25.152.1 to 187.25.159.254187.25.159.2552,046
53187.25.160.0/21187.25.160.1 to 187.25.167.254187.25.167.2552,046
54187.25.168.0/21187.25.168.1 to 187.25.175.254187.25.175.2552,046
55187.25.176.0/21187.25.176.1 to 187.25.183.254187.25.183.2552,046
56187.25.184.0/21187.25.184.1 to 187.25.191.254187.25.191.2552,046
57187.25.192.0/21187.25.192.1 to 187.25.199.254187.25.199.2552,046
58187.25.200.0/21187.25.200.1 to 187.25.207.254187.25.207.2552,046
59187.25.208.0/21187.25.208.1 to 187.25.215.254187.25.215.2552,046
60187.25.216.0/21187.25.216.1 to 187.25.223.254187.25.223.2552,046
61187.25.224.0/21187.25.224.1 to 187.25.231.254187.25.231.2552,046
62187.25.232.0/21187.25.232.1 to 187.25.239.254187.25.239.2552,046
63187.25.240.0/21187.25.240.1 to 187.25.247.254187.25.247.2552,046
64187.25.248.0/21187.25.248.1 to 187.25.255.254187.25.255.2552,046
65187.26.0.0/21187.26.0.1 to 187.26.7.254187.26.7.2552,046
66187.26.8.0/21187.26.8.1 to 187.26.15.254187.26.15.2552,046
67187.26.16.0/21187.26.16.1 to 187.26.23.254187.26.23.2552,046
68187.26.24.0/21187.26.24.1 to 187.26.31.254187.26.31.2552,046
69187.26.32.0/21187.26.32.1 to 187.26.39.254187.26.39.2552,046
70187.26.40.0/21187.26.40.1 to 187.26.47.254187.26.47.2552,046
71187.26.48.0/21187.26.48.1 to 187.26.55.254187.26.55.2552,046
72187.26.56.0/21187.26.56.1 to 187.26.63.254187.26.63.2552,046
73187.26.64.0/21187.26.64.1 to 187.26.71.254187.26.71.2552,046
74187.26.72.0/21187.26.72.1 to 187.26.79.254187.26.79.2552,046
75187.26.80.0/21187.26.80.1 to 187.26.87.254187.26.87.2552,046
76187.26.88.0/21187.26.88.1 to 187.26.95.254187.26.95.2552,046
77187.26.96.0/21187.26.96.1 to 187.26.103.254187.26.103.2552,046
78187.26.104.0/21187.26.104.1 to 187.26.111.254187.26.111.2552,046
79187.26.112.0/21187.26.112.1 to 187.26.119.254187.26.119.2552,046
80187.26.120.0/21187.26.120.1 to 187.26.127.254187.26.127.2552,046
81187.26.128.0/21187.26.128.1 to 187.26.135.254187.26.135.2552,046
82187.26.136.0/21187.26.136.1 to 187.26.143.254187.26.143.2552,046
83187.26.144.0/21187.26.144.1 to 187.26.151.254187.26.151.2552,046
84187.26.152.0/21187.26.152.1 to 187.26.159.254187.26.159.2552,046
85187.26.160.0/21187.26.160.1 to 187.26.167.254187.26.167.2552,046
86187.26.168.0/21187.26.168.1 to 187.26.175.254187.26.175.2552,046
87187.26.176.0/21187.26.176.1 to 187.26.183.254187.26.183.2552,046
88187.26.184.0/21187.26.184.1 to 187.26.191.254187.26.191.2552,046
89187.26.192.0/21187.26.192.1 to 187.26.199.254187.26.199.2552,046
90187.26.200.0/21187.26.200.1 to 187.26.207.254187.26.207.2552,046
91187.26.208.0/21187.26.208.1 to 187.26.215.254187.26.215.2552,046
92187.26.216.0/21187.26.216.1 to 187.26.223.254187.26.223.2552,046
93187.26.224.0/21187.26.224.1 to 187.26.231.254187.26.231.2552,046
94187.26.232.0/21187.26.232.1 to 187.26.239.254187.26.239.2552,046
95187.26.240.0/21187.26.240.1 to 187.26.247.254187.26.247.2552,046
96187.26.248.0/21187.26.248.1 to 187.26.255.254187.26.255.2552,046
97187.27.0.0/21187.27.0.1 to 187.27.7.254187.27.7.2552,046
98187.27.8.0/21187.27.8.1 to 187.27.15.254187.27.15.2552,046
99187.27.16.0/21187.27.16.1 to 187.27.23.254187.27.23.2552,046
100187.27.24.0/21187.27.24.1 to 187.27.31.254187.27.31.2552,046
101187.27.32.0/21187.27.32.1 to 187.27.39.254187.27.39.2552,046
102187.27.40.0/21187.27.40.1 to 187.27.47.254187.27.47.2552,046
103187.27.48.0/21187.27.48.1 to 187.27.55.254187.27.55.2552,046
104187.27.56.0/21187.27.56.1 to 187.27.63.254187.27.63.2552,046
105187.27.64.0/21187.27.64.1 to 187.27.71.254187.27.71.2552,046
106187.27.72.0/21187.27.72.1 to 187.27.79.254187.27.79.2552,046
107187.27.80.0/21187.27.80.1 to 187.27.87.254187.27.87.2552,046
108187.27.88.0/21187.27.88.1 to 187.27.95.254187.27.95.2552,046
109187.27.96.0/21187.27.96.1 to 187.27.103.254187.27.103.2552,046
110187.27.104.0/21187.27.104.1 to 187.27.111.254187.27.111.2552,046
111187.27.112.0/21187.27.112.1 to 187.27.119.254187.27.119.2552,046
112187.27.120.0/21187.27.120.1 to 187.27.127.254187.27.127.2552,046
113187.27.128.0/21187.27.128.1 to 187.27.135.254187.27.135.2552,046
114187.27.136.0/21187.27.136.1 to 187.27.143.254187.27.143.2552,046
115187.27.144.0/21187.27.144.1 to 187.27.151.254187.27.151.2552,046
116187.27.152.0/21187.27.152.1 to 187.27.159.254187.27.159.2552,046
117187.27.160.0/21187.27.160.1 to 187.27.167.254187.27.167.2552,046
118187.27.168.0/21187.27.168.1 to 187.27.175.254187.27.175.2552,046
119187.27.176.0/21187.27.176.1 to 187.27.183.254187.27.183.2552,046
120187.27.184.0/21187.27.184.1 to 187.27.191.254187.27.191.2552,046
121187.27.192.0/21187.27.192.1 to 187.27.199.254187.27.199.2552,046
122187.27.200.0/21187.27.200.1 to 187.27.207.254187.27.207.2552,046
123187.27.208.0/21187.27.208.1 to 187.27.215.254187.27.215.2552,046
124187.27.216.0/21187.27.216.1 to 187.27.223.254187.27.223.2552,046
125187.27.224.0/21187.27.224.1 to 187.27.231.254187.27.231.2552,046
126187.27.232.0/21187.27.232.1 to 187.27.239.254187.27.239.2552,046
127187.27.240.0/21187.27.240.1 to 187.27.247.254187.27.247.2552,046
128187.27.248.0/21187.27.248.1 to 187.27.255.254187.27.255.2552,046
129187.28.0.0/21187.28.0.1 to 187.28.7.254187.28.7.2552,046
130187.28.8.0/21187.28.8.1 to 187.28.15.254187.28.15.2552,046
131187.28.16.0/21187.28.16.1 to 187.28.23.254187.28.23.2552,046
132187.28.24.0/21187.28.24.1 to 187.28.31.254187.28.31.2552,046
133187.28.32.0/21187.28.32.1 to 187.28.39.254187.28.39.2552,046
134187.28.40.0/21187.28.40.1 to 187.28.47.254187.28.47.2552,046
135187.28.48.0/21187.28.48.1 to 187.28.55.254187.28.55.2552,046
136187.28.56.0/21187.28.56.1 to 187.28.63.254187.28.63.2552,046
137187.28.64.0/21187.28.64.1 to 187.28.71.254187.28.71.2552,046
138187.28.72.0/21187.28.72.1 to 187.28.79.254187.28.79.2552,046
139187.28.80.0/21187.28.80.1 to 187.28.87.254187.28.87.2552,046
140187.28.88.0/21187.28.88.1 to 187.28.95.254187.28.95.2552,046
141187.28.96.0/21187.28.96.1 to 187.28.103.254187.28.103.2552,046
142187.28.104.0/21187.28.104.1 to 187.28.111.254187.28.111.2552,046
143187.28.112.0/21187.28.112.1 to 187.28.119.254187.28.119.2552,046
144187.28.120.0/21187.28.120.1 to 187.28.127.254187.28.127.2552,046
145187.28.128.0/21187.28.128.1 to 187.28.135.254187.28.135.2552,046
146187.28.136.0/21187.28.136.1 to 187.28.143.254187.28.143.2552,046
147187.28.144.0/21187.28.144.1 to 187.28.151.254187.28.151.2552,046
148187.28.152.0/21187.28.152.1 to 187.28.159.254187.28.159.2552,046
149187.28.160.0/21187.28.160.1 to 187.28.167.254187.28.167.2552,046
150187.28.168.0/21187.28.168.1 to 187.28.175.254187.28.175.2552,046
151187.28.176.0/21187.28.176.1 to 187.28.183.254187.28.183.2552,046
152187.28.184.0/21187.28.184.1 to 187.28.191.254187.28.191.2552,046
153187.28.192.0/21187.28.192.1 to 187.28.199.254187.28.199.2552,046
154187.28.200.0/21187.28.200.1 to 187.28.207.254187.28.207.2552,046
155187.28.208.0/21187.28.208.1 to 187.28.215.254187.28.215.2552,046
156187.28.216.0/21187.28.216.1 to 187.28.223.254187.28.223.2552,046
157187.28.224.0/21187.28.224.1 to 187.28.231.254187.28.231.2552,046
158187.28.232.0/21187.28.232.1 to 187.28.239.254187.28.239.2552,046
159187.28.240.0/21187.28.240.1 to 187.28.247.254187.28.247.2552,046
160187.28.248.0/21187.28.248.1 to 187.28.255.254187.28.255.2552,046
161187.29.0.0/21187.29.0.1 to 187.29.7.254187.29.7.2552,046
162187.29.8.0/21187.29.8.1 to 187.29.15.254187.29.15.2552,046
163187.29.16.0/21187.29.16.1 to 187.29.23.254187.29.23.2552,046
164187.29.24.0/21187.29.24.1 to 187.29.31.254187.29.31.2552,046
165187.29.32.0/21187.29.32.1 to 187.29.39.254187.29.39.2552,046
166187.29.40.0/21187.29.40.1 to 187.29.47.254187.29.47.2552,046
167187.29.48.0/21187.29.48.1 to 187.29.55.254187.29.55.2552,046
168187.29.56.0/21187.29.56.1 to 187.29.63.254187.29.63.2552,046
169187.29.64.0/21187.29.64.1 to 187.29.71.254187.29.71.2552,046
170187.29.72.0/21187.29.72.1 to 187.29.79.254187.29.79.2552,046
171187.29.80.0/21187.29.80.1 to 187.29.87.254187.29.87.2552,046
172187.29.88.0/21187.29.88.1 to 187.29.95.254187.29.95.2552,046
173187.29.96.0/21187.29.96.1 to 187.29.103.254187.29.103.2552,046
174187.29.104.0/21187.29.104.1 to 187.29.111.254187.29.111.2552,046
175187.29.112.0/21187.29.112.1 to 187.29.119.254187.29.119.2552,046
176187.29.120.0/21187.29.120.1 to 187.29.127.254187.29.127.2552,046
177187.29.128.0/21187.29.128.1 to 187.29.135.254187.29.135.2552,046
178187.29.136.0/21187.29.136.1 to 187.29.143.254187.29.143.2552,046
179187.29.144.0/21187.29.144.1 to 187.29.151.254187.29.151.2552,046
180187.29.152.0/21187.29.152.1 to 187.29.159.254187.29.159.2552,046
181187.29.160.0/21187.29.160.1 to 187.29.167.254187.29.167.2552,046
182187.29.168.0/21187.29.168.1 to 187.29.175.254187.29.175.2552,046
183187.29.176.0/21187.29.176.1 to 187.29.183.254187.29.183.2552,046
184187.29.184.0/21187.29.184.1 to 187.29.191.254187.29.191.2552,046
185187.29.192.0/21187.29.192.1 to 187.29.199.254187.29.199.2552,046
186187.29.200.0/21187.29.200.1 to 187.29.207.254187.29.207.2552,046
187187.29.208.0/21187.29.208.1 to 187.29.215.254187.29.215.2552,046
188187.29.216.0/21187.29.216.1 to 187.29.223.254187.29.223.2552,046
189187.29.224.0/21187.29.224.1 to 187.29.231.254187.29.231.2552,046
190187.29.232.0/21187.29.232.1 to 187.29.239.254187.29.239.2552,046
191187.29.240.0/21187.29.240.1 to 187.29.247.254187.29.247.2552,046
192187.29.248.0/21187.29.248.1 to 187.29.255.254187.29.255.2552,046
193187.30.0.0/21187.30.0.1 to 187.30.7.254187.30.7.2552,046
194187.30.8.0/21187.30.8.1 to 187.30.15.254187.30.15.2552,046
195187.30.16.0/21187.30.16.1 to 187.30.23.254187.30.23.2552,046
196187.30.24.0/21187.30.24.1 to 187.30.31.254187.30.31.2552,046
197187.30.32.0/21187.30.32.1 to 187.30.39.254187.30.39.2552,046
198187.30.40.0/21187.30.40.1 to 187.30.47.254187.30.47.2552,046
199187.30.48.0/21187.30.48.1 to 187.30.55.254187.30.55.2552,046
200187.30.56.0/21187.30.56.1 to 187.30.63.254187.30.63.2552,046
201187.30.64.0/21187.30.64.1 to 187.30.71.254187.30.71.2552,046
202187.30.72.0/21187.30.72.1 to 187.30.79.254187.30.79.2552,046
203187.30.80.0/21187.30.80.1 to 187.30.87.254187.30.87.2552,046
204187.30.88.0/21187.30.88.1 to 187.30.95.254187.30.95.2552,046
205187.30.96.0/21187.30.96.1 to 187.30.103.254187.30.103.2552,046
206187.30.104.0/21187.30.104.1 to 187.30.111.254187.30.111.2552,046
207187.30.112.0/21187.30.112.1 to 187.30.119.254187.30.119.2552,046
208187.30.120.0/21187.30.120.1 to 187.30.127.254187.30.127.2552,046
209187.30.128.0/21187.30.128.1 to 187.30.135.254187.30.135.2552,046
210187.30.136.0/21187.30.136.1 to 187.30.143.254187.30.143.2552,046
211187.30.144.0/21187.30.144.1 to 187.30.151.254187.30.151.2552,046
212187.30.152.0/21187.30.152.1 to 187.30.159.254187.30.159.2552,046
213187.30.160.0/21187.30.160.1 to 187.30.167.254187.30.167.2552,046
214187.30.168.0/21187.30.168.1 to 187.30.175.254187.30.175.2552,046
215187.30.176.0/21187.30.176.1 to 187.30.183.254187.30.183.2552,046
216187.30.184.0/21187.30.184.1 to 187.30.191.254187.30.191.2552,046
217187.30.192.0/21187.30.192.1 to 187.30.199.254187.30.199.2552,046
218187.30.200.0/21187.30.200.1 to 187.30.207.254187.30.207.2552,046
219187.30.208.0/21187.30.208.1 to 187.30.215.254187.30.215.2552,046
220187.30.216.0/21187.30.216.1 to 187.30.223.254187.30.223.2552,046
221187.30.224.0/21187.30.224.1 to 187.30.231.254187.30.231.2552,046
222187.30.232.0/21187.30.232.1 to 187.30.239.254187.30.239.2552,046
223187.30.240.0/21187.30.240.1 to 187.30.247.254187.30.247.2552,046
224187.30.248.0/21187.30.248.1 to 187.30.255.254187.30.255.2552,046
225187.31.0.0/21187.31.0.1 to 187.31.7.254187.31.7.2552,046
226187.31.8.0/21187.31.8.1 to 187.31.15.254187.31.15.2552,046
227187.31.16.0/21187.31.16.1 to 187.31.23.254187.31.23.2552,046
228187.31.24.0/21187.31.24.1 to 187.31.31.254187.31.31.2552,046
229187.31.32.0/21187.31.32.1 to 187.31.39.254187.31.39.2552,046
230187.31.40.0/21187.31.40.1 to 187.31.47.254187.31.47.2552,046
231187.31.48.0/21187.31.48.1 to 187.31.55.254187.31.55.2552,046
232187.31.56.0/21187.31.56.1 to 187.31.63.254187.31.63.2552,046
233187.31.64.0/21187.31.64.1 to 187.31.71.254187.31.71.2552,046
234187.31.72.0/21187.31.72.1 to 187.31.79.254187.31.79.2552,046
235187.31.80.0/21187.31.80.1 to 187.31.87.254187.31.87.2552,046
236187.31.88.0/21187.31.88.1 to 187.31.95.254187.31.95.2552,046
237187.31.96.0/21187.31.96.1 to 187.31.103.254187.31.103.2552,046
238187.31.104.0/21187.31.104.1 to 187.31.111.254187.31.111.2552,046
239187.31.112.0/21187.31.112.1 to 187.31.119.254187.31.119.2552,046
240187.31.120.0/21187.31.120.1 to 187.31.127.254187.31.127.2552,046
241187.31.128.0/21187.31.128.1 to 187.31.135.254187.31.135.2552,046
242187.31.136.0/21187.31.136.1 to 187.31.143.254187.31.143.2552,046
243187.31.144.0/21187.31.144.1 to 187.31.151.254187.31.151.2552,046
244187.31.152.0/21187.31.152.1 to 187.31.159.254187.31.159.2552,046
245187.31.160.0/21187.31.160.1 to 187.31.167.254187.31.167.2552,046
246187.31.168.0/21187.31.168.1 to 187.31.175.254187.31.175.2552,046
247187.31.176.0/21187.31.176.1 to 187.31.183.254187.31.183.2552,046
248187.31.184.0/21187.31.184.1 to 187.31.191.254187.31.191.2552,046
249187.31.192.0/21187.31.192.1 to 187.31.199.254187.31.199.2552,046
250187.31.200.0/21187.31.200.1 to 187.31.207.254187.31.207.2552,046
251187.31.208.0/21187.31.208.1 to 187.31.215.254187.31.215.2552,046
252187.31.216.0/21187.31.216.1 to 187.31.223.254187.31.223.2552,046
253187.31.224.0/21187.31.224.1 to 187.31.231.254187.31.231.2552,046
254187.31.232.0/21187.31.232.1 to 187.31.239.254187.31.239.2552,046
255187.31.240.0/21187.31.240.1 to 187.31.247.254187.31.247.2552,046
256187.31.248.0/21187.31.248.1 to 187.31.255.254187.31.255.2552,046

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.