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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.

Network187.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
187.0.0.0
Broadcast address
187.255.255.255
First usable
187.0.0.1
Last usable
187.255.255.254
Usable hosts
16,777,214 (16,777,216 less the network and broadcast addresses)
Subnet mask
255.0.0.0
Wildcard mask
0.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/8
Type
Public public
Old class
B (default /16)
As numbers
Hex BB000000 · Integer 3137339392 to 3154116607
Reverse DNS zone
187.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10111011..00000000.00000000.00000000187.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network10111011..00000000.00000000.00000000187.0.0.0
Broadcast10111011..11111111.11111111.11111111187.255.255.255
Split into smaller subnets/20
/9 (2)/10 (4)/11 (8)/12 (16)/13 (32)/14 (64)/15 (128)/16 (256)/17 (512)/18 (1,024)/19 (2,048)/20 (4,096)

187.0.0.0/8 makes 4,096 subnets of /20; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1187.0.0.0/20187.0.0.1 to 187.0.15.254187.0.15.2554,094
2187.0.16.0/20187.0.16.1 to 187.0.31.254187.0.31.2554,094
3187.0.32.0/20187.0.32.1 to 187.0.47.254187.0.47.2554,094
4187.0.48.0/20187.0.48.1 to 187.0.63.254187.0.63.2554,094
5187.0.64.0/20187.0.64.1 to 187.0.79.254187.0.79.2554,094
6187.0.80.0/20187.0.80.1 to 187.0.95.254187.0.95.2554,094
7187.0.96.0/20187.0.96.1 to 187.0.111.254187.0.111.2554,094
8187.0.112.0/20187.0.112.1 to 187.0.127.254187.0.127.2554,094
9187.0.128.0/20187.0.128.1 to 187.0.143.254187.0.143.2554,094
10187.0.144.0/20187.0.144.1 to 187.0.159.254187.0.159.2554,094
11187.0.160.0/20187.0.160.1 to 187.0.175.254187.0.175.2554,094
12187.0.176.0/20187.0.176.1 to 187.0.191.254187.0.191.2554,094
13187.0.192.0/20187.0.192.1 to 187.0.207.254187.0.207.2554,094
14187.0.208.0/20187.0.208.1 to 187.0.223.254187.0.223.2554,094
15187.0.224.0/20187.0.224.1 to 187.0.239.254187.0.239.2554,094
16187.0.240.0/20187.0.240.1 to 187.0.255.254187.0.255.2554,094
17187.1.0.0/20187.1.0.1 to 187.1.15.254187.1.15.2554,094
18187.1.16.0/20187.1.16.1 to 187.1.31.254187.1.31.2554,094
19187.1.32.0/20187.1.32.1 to 187.1.47.254187.1.47.2554,094
20187.1.48.0/20187.1.48.1 to 187.1.63.254187.1.63.2554,094
21187.1.64.0/20187.1.64.1 to 187.1.79.254187.1.79.2554,094
22187.1.80.0/20187.1.80.1 to 187.1.95.254187.1.95.2554,094
23187.1.96.0/20187.1.96.1 to 187.1.111.254187.1.111.2554,094
24187.1.112.0/20187.1.112.1 to 187.1.127.254187.1.127.2554,094
25187.1.128.0/20187.1.128.1 to 187.1.143.254187.1.143.2554,094
26187.1.144.0/20187.1.144.1 to 187.1.159.254187.1.159.2554,094
27187.1.160.0/20187.1.160.1 to 187.1.175.254187.1.175.2554,094
28187.1.176.0/20187.1.176.1 to 187.1.191.254187.1.191.2554,094
29187.1.192.0/20187.1.192.1 to 187.1.207.254187.1.207.2554,094
30187.1.208.0/20187.1.208.1 to 187.1.223.254187.1.223.2554,094
31187.1.224.0/20187.1.224.1 to 187.1.239.254187.1.239.2554,094
32187.1.240.0/20187.1.240.1 to 187.1.255.254187.1.255.2554,094
33187.2.0.0/20187.2.0.1 to 187.2.15.254187.2.15.2554,094
34187.2.16.0/20187.2.16.1 to 187.2.31.254187.2.31.2554,094
35187.2.32.0/20187.2.32.1 to 187.2.47.254187.2.47.2554,094
36187.2.48.0/20187.2.48.1 to 187.2.63.254187.2.63.2554,094
37187.2.64.0/20187.2.64.1 to 187.2.79.254187.2.79.2554,094
38187.2.80.0/20187.2.80.1 to 187.2.95.254187.2.95.2554,094
39187.2.96.0/20187.2.96.1 to 187.2.111.254187.2.111.2554,094
40187.2.112.0/20187.2.112.1 to 187.2.127.254187.2.127.2554,094
41187.2.128.0/20187.2.128.1 to 187.2.143.254187.2.143.2554,094
42187.2.144.0/20187.2.144.1 to 187.2.159.254187.2.159.2554,094
43187.2.160.0/20187.2.160.1 to 187.2.175.254187.2.175.2554,094
44187.2.176.0/20187.2.176.1 to 187.2.191.254187.2.191.2554,094
45187.2.192.0/20187.2.192.1 to 187.2.207.254187.2.207.2554,094
46187.2.208.0/20187.2.208.1 to 187.2.223.254187.2.223.2554,094
47187.2.224.0/20187.2.224.1 to 187.2.239.254187.2.239.2554,094
48187.2.240.0/20187.2.240.1 to 187.2.255.254187.2.255.2554,094
49187.3.0.0/20187.3.0.1 to 187.3.15.254187.3.15.2554,094
50187.3.16.0/20187.3.16.1 to 187.3.31.254187.3.31.2554,094
51187.3.32.0/20187.3.32.1 to 187.3.47.254187.3.47.2554,094
52187.3.48.0/20187.3.48.1 to 187.3.63.254187.3.63.2554,094
53187.3.64.0/20187.3.64.1 to 187.3.79.254187.3.79.2554,094
54187.3.80.0/20187.3.80.1 to 187.3.95.254187.3.95.2554,094
55187.3.96.0/20187.3.96.1 to 187.3.111.254187.3.111.2554,094
56187.3.112.0/20187.3.112.1 to 187.3.127.254187.3.127.2554,094
57187.3.128.0/20187.3.128.1 to 187.3.143.254187.3.143.2554,094
58187.3.144.0/20187.3.144.1 to 187.3.159.254187.3.159.2554,094
59187.3.160.0/20187.3.160.1 to 187.3.175.254187.3.175.2554,094
60187.3.176.0/20187.3.176.1 to 187.3.191.254187.3.191.2554,094
61187.3.192.0/20187.3.192.1 to 187.3.207.254187.3.207.2554,094
62187.3.208.0/20187.3.208.1 to 187.3.223.254187.3.223.2554,094
63187.3.224.0/20187.3.224.1 to 187.3.239.254187.3.239.2554,094
64187.3.240.0/20187.3.240.1 to 187.3.255.254187.3.255.2554,094
65187.4.0.0/20187.4.0.1 to 187.4.15.254187.4.15.2554,094
66187.4.16.0/20187.4.16.1 to 187.4.31.254187.4.31.2554,094
67187.4.32.0/20187.4.32.1 to 187.4.47.254187.4.47.2554,094
68187.4.48.0/20187.4.48.1 to 187.4.63.254187.4.63.2554,094
69187.4.64.0/20187.4.64.1 to 187.4.79.254187.4.79.2554,094
70187.4.80.0/20187.4.80.1 to 187.4.95.254187.4.95.2554,094
71187.4.96.0/20187.4.96.1 to 187.4.111.254187.4.111.2554,094
72187.4.112.0/20187.4.112.1 to 187.4.127.254187.4.127.2554,094
73187.4.128.0/20187.4.128.1 to 187.4.143.254187.4.143.2554,094
74187.4.144.0/20187.4.144.1 to 187.4.159.254187.4.159.2554,094
75187.4.160.0/20187.4.160.1 to 187.4.175.254187.4.175.2554,094
76187.4.176.0/20187.4.176.1 to 187.4.191.254187.4.191.2554,094
77187.4.192.0/20187.4.192.1 to 187.4.207.254187.4.207.2554,094
78187.4.208.0/20187.4.208.1 to 187.4.223.254187.4.223.2554,094
79187.4.224.0/20187.4.224.1 to 187.4.239.254187.4.239.2554,094
80187.4.240.0/20187.4.240.1 to 187.4.255.254187.4.255.2554,094
81187.5.0.0/20187.5.0.1 to 187.5.15.254187.5.15.2554,094
82187.5.16.0/20187.5.16.1 to 187.5.31.254187.5.31.2554,094
83187.5.32.0/20187.5.32.1 to 187.5.47.254187.5.47.2554,094
84187.5.48.0/20187.5.48.1 to 187.5.63.254187.5.63.2554,094
85187.5.64.0/20187.5.64.1 to 187.5.79.254187.5.79.2554,094
86187.5.80.0/20187.5.80.1 to 187.5.95.254187.5.95.2554,094
87187.5.96.0/20187.5.96.1 to 187.5.111.254187.5.111.2554,094
88187.5.112.0/20187.5.112.1 to 187.5.127.254187.5.127.2554,094
89187.5.128.0/20187.5.128.1 to 187.5.143.254187.5.143.2554,094
90187.5.144.0/20187.5.144.1 to 187.5.159.254187.5.159.2554,094
91187.5.160.0/20187.5.160.1 to 187.5.175.254187.5.175.2554,094
92187.5.176.0/20187.5.176.1 to 187.5.191.254187.5.191.2554,094
93187.5.192.0/20187.5.192.1 to 187.5.207.254187.5.207.2554,094
94187.5.208.0/20187.5.208.1 to 187.5.223.254187.5.223.2554,094
95187.5.224.0/20187.5.224.1 to 187.5.239.254187.5.239.2554,094
96187.5.240.0/20187.5.240.1 to 187.5.255.254187.5.255.2554,094
97187.6.0.0/20187.6.0.1 to 187.6.15.254187.6.15.2554,094
98187.6.16.0/20187.6.16.1 to 187.6.31.254187.6.31.2554,094
99187.6.32.0/20187.6.32.1 to 187.6.47.254187.6.47.2554,094
100187.6.48.0/20187.6.48.1 to 187.6.63.254187.6.63.2554,094
101187.6.64.0/20187.6.64.1 to 187.6.79.254187.6.79.2554,094
102187.6.80.0/20187.6.80.1 to 187.6.95.254187.6.95.2554,094
103187.6.96.0/20187.6.96.1 to 187.6.111.254187.6.111.2554,094
104187.6.112.0/20187.6.112.1 to 187.6.127.254187.6.127.2554,094
105187.6.128.0/20187.6.128.1 to 187.6.143.254187.6.143.2554,094
106187.6.144.0/20187.6.144.1 to 187.6.159.254187.6.159.2554,094
107187.6.160.0/20187.6.160.1 to 187.6.175.254187.6.175.2554,094
108187.6.176.0/20187.6.176.1 to 187.6.191.254187.6.191.2554,094
109187.6.192.0/20187.6.192.1 to 187.6.207.254187.6.207.2554,094
110187.6.208.0/20187.6.208.1 to 187.6.223.254187.6.223.2554,094
111187.6.224.0/20187.6.224.1 to 187.6.239.254187.6.239.2554,094
112187.6.240.0/20187.6.240.1 to 187.6.255.254187.6.255.2554,094
113187.7.0.0/20187.7.0.1 to 187.7.15.254187.7.15.2554,094
114187.7.16.0/20187.7.16.1 to 187.7.31.254187.7.31.2554,094
115187.7.32.0/20187.7.32.1 to 187.7.47.254187.7.47.2554,094
116187.7.48.0/20187.7.48.1 to 187.7.63.254187.7.63.2554,094
117187.7.64.0/20187.7.64.1 to 187.7.79.254187.7.79.2554,094
118187.7.80.0/20187.7.80.1 to 187.7.95.254187.7.95.2554,094
119187.7.96.0/20187.7.96.1 to 187.7.111.254187.7.111.2554,094
120187.7.112.0/20187.7.112.1 to 187.7.127.254187.7.127.2554,094
121187.7.128.0/20187.7.128.1 to 187.7.143.254187.7.143.2554,094
122187.7.144.0/20187.7.144.1 to 187.7.159.254187.7.159.2554,094
123187.7.160.0/20187.7.160.1 to 187.7.175.254187.7.175.2554,094
124187.7.176.0/20187.7.176.1 to 187.7.191.254187.7.191.2554,094
125187.7.192.0/20187.7.192.1 to 187.7.207.254187.7.207.2554,094
126187.7.208.0/20187.7.208.1 to 187.7.223.254187.7.223.2554,094
127187.7.224.0/20187.7.224.1 to 187.7.239.254187.7.239.2554,094
128187.7.240.0/20187.7.240.1 to 187.7.255.254187.7.255.2554,094
129187.8.0.0/20187.8.0.1 to 187.8.15.254187.8.15.2554,094
130187.8.16.0/20187.8.16.1 to 187.8.31.254187.8.31.2554,094
131187.8.32.0/20187.8.32.1 to 187.8.47.254187.8.47.2554,094
132187.8.48.0/20187.8.48.1 to 187.8.63.254187.8.63.2554,094
133187.8.64.0/20187.8.64.1 to 187.8.79.254187.8.79.2554,094
134187.8.80.0/20187.8.80.1 to 187.8.95.254187.8.95.2554,094
135187.8.96.0/20187.8.96.1 to 187.8.111.254187.8.111.2554,094
136187.8.112.0/20187.8.112.1 to 187.8.127.254187.8.127.2554,094
137187.8.128.0/20187.8.128.1 to 187.8.143.254187.8.143.2554,094
138187.8.144.0/20187.8.144.1 to 187.8.159.254187.8.159.2554,094
139187.8.160.0/20187.8.160.1 to 187.8.175.254187.8.175.2554,094
140187.8.176.0/20187.8.176.1 to 187.8.191.254187.8.191.2554,094
141187.8.192.0/20187.8.192.1 to 187.8.207.254187.8.207.2554,094
142187.8.208.0/20187.8.208.1 to 187.8.223.254187.8.223.2554,094
143187.8.224.0/20187.8.224.1 to 187.8.239.254187.8.239.2554,094
144187.8.240.0/20187.8.240.1 to 187.8.255.254187.8.255.2554,094
145187.9.0.0/20187.9.0.1 to 187.9.15.254187.9.15.2554,094
146187.9.16.0/20187.9.16.1 to 187.9.31.254187.9.31.2554,094
147187.9.32.0/20187.9.32.1 to 187.9.47.254187.9.47.2554,094
148187.9.48.0/20187.9.48.1 to 187.9.63.254187.9.63.2554,094
149187.9.64.0/20187.9.64.1 to 187.9.79.254187.9.79.2554,094
150187.9.80.0/20187.9.80.1 to 187.9.95.254187.9.95.2554,094
151187.9.96.0/20187.9.96.1 to 187.9.111.254187.9.111.2554,094
152187.9.112.0/20187.9.112.1 to 187.9.127.254187.9.127.2554,094
153187.9.128.0/20187.9.128.1 to 187.9.143.254187.9.143.2554,094
154187.9.144.0/20187.9.144.1 to 187.9.159.254187.9.159.2554,094
155187.9.160.0/20187.9.160.1 to 187.9.175.254187.9.175.2554,094
156187.9.176.0/20187.9.176.1 to 187.9.191.254187.9.191.2554,094
157187.9.192.0/20187.9.192.1 to 187.9.207.254187.9.207.2554,094
158187.9.208.0/20187.9.208.1 to 187.9.223.254187.9.223.2554,094
159187.9.224.0/20187.9.224.1 to 187.9.239.254187.9.239.2554,094
160187.9.240.0/20187.9.240.1 to 187.9.255.254187.9.255.2554,094
161187.10.0.0/20187.10.0.1 to 187.10.15.254187.10.15.2554,094
162187.10.16.0/20187.10.16.1 to 187.10.31.254187.10.31.2554,094
163187.10.32.0/20187.10.32.1 to 187.10.47.254187.10.47.2554,094
164187.10.48.0/20187.10.48.1 to 187.10.63.254187.10.63.2554,094
165187.10.64.0/20187.10.64.1 to 187.10.79.254187.10.79.2554,094
166187.10.80.0/20187.10.80.1 to 187.10.95.254187.10.95.2554,094
167187.10.96.0/20187.10.96.1 to 187.10.111.254187.10.111.2554,094
168187.10.112.0/20187.10.112.1 to 187.10.127.254187.10.127.2554,094
169187.10.128.0/20187.10.128.1 to 187.10.143.254187.10.143.2554,094
170187.10.144.0/20187.10.144.1 to 187.10.159.254187.10.159.2554,094
171187.10.160.0/20187.10.160.1 to 187.10.175.254187.10.175.2554,094
172187.10.176.0/20187.10.176.1 to 187.10.191.254187.10.191.2554,094
173187.10.192.0/20187.10.192.1 to 187.10.207.254187.10.207.2554,094
174187.10.208.0/20187.10.208.1 to 187.10.223.254187.10.223.2554,094
175187.10.224.0/20187.10.224.1 to 187.10.239.254187.10.239.2554,094
176187.10.240.0/20187.10.240.1 to 187.10.255.254187.10.255.2554,094
177187.11.0.0/20187.11.0.1 to 187.11.15.254187.11.15.2554,094
178187.11.16.0/20187.11.16.1 to 187.11.31.254187.11.31.2554,094
179187.11.32.0/20187.11.32.1 to 187.11.47.254187.11.47.2554,094
180187.11.48.0/20187.11.48.1 to 187.11.63.254187.11.63.2554,094
181187.11.64.0/20187.11.64.1 to 187.11.79.254187.11.79.2554,094
182187.11.80.0/20187.11.80.1 to 187.11.95.254187.11.95.2554,094
183187.11.96.0/20187.11.96.1 to 187.11.111.254187.11.111.2554,094
184187.11.112.0/20187.11.112.1 to 187.11.127.254187.11.127.2554,094
185187.11.128.0/20187.11.128.1 to 187.11.143.254187.11.143.2554,094
186187.11.144.0/20187.11.144.1 to 187.11.159.254187.11.159.2554,094
187187.11.160.0/20187.11.160.1 to 187.11.175.254187.11.175.2554,094
188187.11.176.0/20187.11.176.1 to 187.11.191.254187.11.191.2554,094
189187.11.192.0/20187.11.192.1 to 187.11.207.254187.11.207.2554,094
190187.11.208.0/20187.11.208.1 to 187.11.223.254187.11.223.2554,094
191187.11.224.0/20187.11.224.1 to 187.11.239.254187.11.239.2554,094
192187.11.240.0/20187.11.240.1 to 187.11.255.254187.11.255.2554,094
193187.12.0.0/20187.12.0.1 to 187.12.15.254187.12.15.2554,094
194187.12.16.0/20187.12.16.1 to 187.12.31.254187.12.31.2554,094
195187.12.32.0/20187.12.32.1 to 187.12.47.254187.12.47.2554,094
196187.12.48.0/20187.12.48.1 to 187.12.63.254187.12.63.2554,094
197187.12.64.0/20187.12.64.1 to 187.12.79.254187.12.79.2554,094
198187.12.80.0/20187.12.80.1 to 187.12.95.254187.12.95.2554,094
199187.12.96.0/20187.12.96.1 to 187.12.111.254187.12.111.2554,094
200187.12.112.0/20187.12.112.1 to 187.12.127.254187.12.127.2554,094
201187.12.128.0/20187.12.128.1 to 187.12.143.254187.12.143.2554,094
202187.12.144.0/20187.12.144.1 to 187.12.159.254187.12.159.2554,094
203187.12.160.0/20187.12.160.1 to 187.12.175.254187.12.175.2554,094
204187.12.176.0/20187.12.176.1 to 187.12.191.254187.12.191.2554,094
205187.12.192.0/20187.12.192.1 to 187.12.207.254187.12.207.2554,094
206187.12.208.0/20187.12.208.1 to 187.12.223.254187.12.223.2554,094
207187.12.224.0/20187.12.224.1 to 187.12.239.254187.12.239.2554,094
208187.12.240.0/20187.12.240.1 to 187.12.255.254187.12.255.2554,094
209187.13.0.0/20187.13.0.1 to 187.13.15.254187.13.15.2554,094
210187.13.16.0/20187.13.16.1 to 187.13.31.254187.13.31.2554,094
211187.13.32.0/20187.13.32.1 to 187.13.47.254187.13.47.2554,094
212187.13.48.0/20187.13.48.1 to 187.13.63.254187.13.63.2554,094
213187.13.64.0/20187.13.64.1 to 187.13.79.254187.13.79.2554,094
214187.13.80.0/20187.13.80.1 to 187.13.95.254187.13.95.2554,094
215187.13.96.0/20187.13.96.1 to 187.13.111.254187.13.111.2554,094
216187.13.112.0/20187.13.112.1 to 187.13.127.254187.13.127.2554,094
217187.13.128.0/20187.13.128.1 to 187.13.143.254187.13.143.2554,094
218187.13.144.0/20187.13.144.1 to 187.13.159.254187.13.159.2554,094
219187.13.160.0/20187.13.160.1 to 187.13.175.254187.13.175.2554,094
220187.13.176.0/20187.13.176.1 to 187.13.191.254187.13.191.2554,094
221187.13.192.0/20187.13.192.1 to 187.13.207.254187.13.207.2554,094
222187.13.208.0/20187.13.208.1 to 187.13.223.254187.13.223.2554,094
223187.13.224.0/20187.13.224.1 to 187.13.239.254187.13.239.2554,094
224187.13.240.0/20187.13.240.1 to 187.13.255.254187.13.255.2554,094
225187.14.0.0/20187.14.0.1 to 187.14.15.254187.14.15.2554,094
226187.14.16.0/20187.14.16.1 to 187.14.31.254187.14.31.2554,094
227187.14.32.0/20187.14.32.1 to 187.14.47.254187.14.47.2554,094
228187.14.48.0/20187.14.48.1 to 187.14.63.254187.14.63.2554,094
229187.14.64.0/20187.14.64.1 to 187.14.79.254187.14.79.2554,094
230187.14.80.0/20187.14.80.1 to 187.14.95.254187.14.95.2554,094
231187.14.96.0/20187.14.96.1 to 187.14.111.254187.14.111.2554,094
232187.14.112.0/20187.14.112.1 to 187.14.127.254187.14.127.2554,094
233187.14.128.0/20187.14.128.1 to 187.14.143.254187.14.143.2554,094
234187.14.144.0/20187.14.144.1 to 187.14.159.254187.14.159.2554,094
235187.14.160.0/20187.14.160.1 to 187.14.175.254187.14.175.2554,094
236187.14.176.0/20187.14.176.1 to 187.14.191.254187.14.191.2554,094
237187.14.192.0/20187.14.192.1 to 187.14.207.254187.14.207.2554,094
238187.14.208.0/20187.14.208.1 to 187.14.223.254187.14.223.2554,094
239187.14.224.0/20187.14.224.1 to 187.14.239.254187.14.239.2554,094
240187.14.240.0/20187.14.240.1 to 187.14.255.254187.14.255.2554,094
241187.15.0.0/20187.15.0.1 to 187.15.15.254187.15.15.2554,094
242187.15.16.0/20187.15.16.1 to 187.15.31.254187.15.31.2554,094
243187.15.32.0/20187.15.32.1 to 187.15.47.254187.15.47.2554,094
244187.15.48.0/20187.15.48.1 to 187.15.63.254187.15.63.2554,094
245187.15.64.0/20187.15.64.1 to 187.15.79.254187.15.79.2554,094
246187.15.80.0/20187.15.80.1 to 187.15.95.254187.15.95.2554,094
247187.15.96.0/20187.15.96.1 to 187.15.111.254187.15.111.2554,094
248187.15.112.0/20187.15.112.1 to 187.15.127.254187.15.127.2554,094
249187.15.128.0/20187.15.128.1 to 187.15.143.254187.15.143.2554,094
250187.15.144.0/20187.15.144.1 to 187.15.159.254187.15.159.2554,094
251187.15.160.0/20187.15.160.1 to 187.15.175.254187.15.175.2554,094
252187.15.176.0/20187.15.176.1 to 187.15.191.254187.15.191.2554,094
253187.15.192.0/20187.15.192.1 to 187.15.207.254187.15.207.2554,094
254187.15.208.0/20187.15.208.1 to 187.15.223.254187.15.223.2554,094
255187.15.224.0/20187.15.224.1 to 187.15.239.254187.15.239.2554,094
256187.15.240.0/20187.15.240.1 to 187.15.255.254187.15.255.2554,094

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.