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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/18
/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 1,024 subnets of /18; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1187.0.0.0/18187.0.0.1 to 187.0.63.254187.0.63.25516,382
2187.0.64.0/18187.0.64.1 to 187.0.127.254187.0.127.25516,382
3187.0.128.0/18187.0.128.1 to 187.0.191.254187.0.191.25516,382
4187.0.192.0/18187.0.192.1 to 187.0.255.254187.0.255.25516,382
5187.1.0.0/18187.1.0.1 to 187.1.63.254187.1.63.25516,382
6187.1.64.0/18187.1.64.1 to 187.1.127.254187.1.127.25516,382
7187.1.128.0/18187.1.128.1 to 187.1.191.254187.1.191.25516,382
8187.1.192.0/18187.1.192.1 to 187.1.255.254187.1.255.25516,382
9187.2.0.0/18187.2.0.1 to 187.2.63.254187.2.63.25516,382
10187.2.64.0/18187.2.64.1 to 187.2.127.254187.2.127.25516,382
11187.2.128.0/18187.2.128.1 to 187.2.191.254187.2.191.25516,382
12187.2.192.0/18187.2.192.1 to 187.2.255.254187.2.255.25516,382
13187.3.0.0/18187.3.0.1 to 187.3.63.254187.3.63.25516,382
14187.3.64.0/18187.3.64.1 to 187.3.127.254187.3.127.25516,382
15187.3.128.0/18187.3.128.1 to 187.3.191.254187.3.191.25516,382
16187.3.192.0/18187.3.192.1 to 187.3.255.254187.3.255.25516,382
17187.4.0.0/18187.4.0.1 to 187.4.63.254187.4.63.25516,382
18187.4.64.0/18187.4.64.1 to 187.4.127.254187.4.127.25516,382
19187.4.128.0/18187.4.128.1 to 187.4.191.254187.4.191.25516,382
20187.4.192.0/18187.4.192.1 to 187.4.255.254187.4.255.25516,382
21187.5.0.0/18187.5.0.1 to 187.5.63.254187.5.63.25516,382
22187.5.64.0/18187.5.64.1 to 187.5.127.254187.5.127.25516,382
23187.5.128.0/18187.5.128.1 to 187.5.191.254187.5.191.25516,382
24187.5.192.0/18187.5.192.1 to 187.5.255.254187.5.255.25516,382
25187.6.0.0/18187.6.0.1 to 187.6.63.254187.6.63.25516,382
26187.6.64.0/18187.6.64.1 to 187.6.127.254187.6.127.25516,382
27187.6.128.0/18187.6.128.1 to 187.6.191.254187.6.191.25516,382
28187.6.192.0/18187.6.192.1 to 187.6.255.254187.6.255.25516,382
29187.7.0.0/18187.7.0.1 to 187.7.63.254187.7.63.25516,382
30187.7.64.0/18187.7.64.1 to 187.7.127.254187.7.127.25516,382
31187.7.128.0/18187.7.128.1 to 187.7.191.254187.7.191.25516,382
32187.7.192.0/18187.7.192.1 to 187.7.255.254187.7.255.25516,382
33187.8.0.0/18187.8.0.1 to 187.8.63.254187.8.63.25516,382
34187.8.64.0/18187.8.64.1 to 187.8.127.254187.8.127.25516,382
35187.8.128.0/18187.8.128.1 to 187.8.191.254187.8.191.25516,382
36187.8.192.0/18187.8.192.1 to 187.8.255.254187.8.255.25516,382
37187.9.0.0/18187.9.0.1 to 187.9.63.254187.9.63.25516,382
38187.9.64.0/18187.9.64.1 to 187.9.127.254187.9.127.25516,382
39187.9.128.0/18187.9.128.1 to 187.9.191.254187.9.191.25516,382
40187.9.192.0/18187.9.192.1 to 187.9.255.254187.9.255.25516,382
41187.10.0.0/18187.10.0.1 to 187.10.63.254187.10.63.25516,382
42187.10.64.0/18187.10.64.1 to 187.10.127.254187.10.127.25516,382
43187.10.128.0/18187.10.128.1 to 187.10.191.254187.10.191.25516,382
44187.10.192.0/18187.10.192.1 to 187.10.255.254187.10.255.25516,382
45187.11.0.0/18187.11.0.1 to 187.11.63.254187.11.63.25516,382
46187.11.64.0/18187.11.64.1 to 187.11.127.254187.11.127.25516,382
47187.11.128.0/18187.11.128.1 to 187.11.191.254187.11.191.25516,382
48187.11.192.0/18187.11.192.1 to 187.11.255.254187.11.255.25516,382
49187.12.0.0/18187.12.0.1 to 187.12.63.254187.12.63.25516,382
50187.12.64.0/18187.12.64.1 to 187.12.127.254187.12.127.25516,382
51187.12.128.0/18187.12.128.1 to 187.12.191.254187.12.191.25516,382
52187.12.192.0/18187.12.192.1 to 187.12.255.254187.12.255.25516,382
53187.13.0.0/18187.13.0.1 to 187.13.63.254187.13.63.25516,382
54187.13.64.0/18187.13.64.1 to 187.13.127.254187.13.127.25516,382
55187.13.128.0/18187.13.128.1 to 187.13.191.254187.13.191.25516,382
56187.13.192.0/18187.13.192.1 to 187.13.255.254187.13.255.25516,382
57187.14.0.0/18187.14.0.1 to 187.14.63.254187.14.63.25516,382
58187.14.64.0/18187.14.64.1 to 187.14.127.254187.14.127.25516,382
59187.14.128.0/18187.14.128.1 to 187.14.191.254187.14.191.25516,382
60187.14.192.0/18187.14.192.1 to 187.14.255.254187.14.255.25516,382
61187.15.0.0/18187.15.0.1 to 187.15.63.254187.15.63.25516,382
62187.15.64.0/18187.15.64.1 to 187.15.127.254187.15.127.25516,382
63187.15.128.0/18187.15.128.1 to 187.15.191.254187.15.191.25516,382
64187.15.192.0/18187.15.192.1 to 187.15.255.254187.15.255.25516,382
65187.16.0.0/18187.16.0.1 to 187.16.63.254187.16.63.25516,382
66187.16.64.0/18187.16.64.1 to 187.16.127.254187.16.127.25516,382
67187.16.128.0/18187.16.128.1 to 187.16.191.254187.16.191.25516,382
68187.16.192.0/18187.16.192.1 to 187.16.255.254187.16.255.25516,382
69187.17.0.0/18187.17.0.1 to 187.17.63.254187.17.63.25516,382
70187.17.64.0/18187.17.64.1 to 187.17.127.254187.17.127.25516,382
71187.17.128.0/18187.17.128.1 to 187.17.191.254187.17.191.25516,382
72187.17.192.0/18187.17.192.1 to 187.17.255.254187.17.255.25516,382
73187.18.0.0/18187.18.0.1 to 187.18.63.254187.18.63.25516,382
74187.18.64.0/18187.18.64.1 to 187.18.127.254187.18.127.25516,382
75187.18.128.0/18187.18.128.1 to 187.18.191.254187.18.191.25516,382
76187.18.192.0/18187.18.192.1 to 187.18.255.254187.18.255.25516,382
77187.19.0.0/18187.19.0.1 to 187.19.63.254187.19.63.25516,382
78187.19.64.0/18187.19.64.1 to 187.19.127.254187.19.127.25516,382
79187.19.128.0/18187.19.128.1 to 187.19.191.254187.19.191.25516,382
80187.19.192.0/18187.19.192.1 to 187.19.255.254187.19.255.25516,382
81187.20.0.0/18187.20.0.1 to 187.20.63.254187.20.63.25516,382
82187.20.64.0/18187.20.64.1 to 187.20.127.254187.20.127.25516,382
83187.20.128.0/18187.20.128.1 to 187.20.191.254187.20.191.25516,382
84187.20.192.0/18187.20.192.1 to 187.20.255.254187.20.255.25516,382
85187.21.0.0/18187.21.0.1 to 187.21.63.254187.21.63.25516,382
86187.21.64.0/18187.21.64.1 to 187.21.127.254187.21.127.25516,382
87187.21.128.0/18187.21.128.1 to 187.21.191.254187.21.191.25516,382
88187.21.192.0/18187.21.192.1 to 187.21.255.254187.21.255.25516,382
89187.22.0.0/18187.22.0.1 to 187.22.63.254187.22.63.25516,382
90187.22.64.0/18187.22.64.1 to 187.22.127.254187.22.127.25516,382
91187.22.128.0/18187.22.128.1 to 187.22.191.254187.22.191.25516,382
92187.22.192.0/18187.22.192.1 to 187.22.255.254187.22.255.25516,382
93187.23.0.0/18187.23.0.1 to 187.23.63.254187.23.63.25516,382
94187.23.64.0/18187.23.64.1 to 187.23.127.254187.23.127.25516,382
95187.23.128.0/18187.23.128.1 to 187.23.191.254187.23.191.25516,382
96187.23.192.0/18187.23.192.1 to 187.23.255.254187.23.255.25516,382
97187.24.0.0/18187.24.0.1 to 187.24.63.254187.24.63.25516,382
98187.24.64.0/18187.24.64.1 to 187.24.127.254187.24.127.25516,382
99187.24.128.0/18187.24.128.1 to 187.24.191.254187.24.191.25516,382
100187.24.192.0/18187.24.192.1 to 187.24.255.254187.24.255.25516,382
101187.25.0.0/18187.25.0.1 to 187.25.63.254187.25.63.25516,382
102187.25.64.0/18187.25.64.1 to 187.25.127.254187.25.127.25516,382
103187.25.128.0/18187.25.128.1 to 187.25.191.254187.25.191.25516,382
104187.25.192.0/18187.25.192.1 to 187.25.255.254187.25.255.25516,382
105187.26.0.0/18187.26.0.1 to 187.26.63.254187.26.63.25516,382
106187.26.64.0/18187.26.64.1 to 187.26.127.254187.26.127.25516,382
107187.26.128.0/18187.26.128.1 to 187.26.191.254187.26.191.25516,382
108187.26.192.0/18187.26.192.1 to 187.26.255.254187.26.255.25516,382
109187.27.0.0/18187.27.0.1 to 187.27.63.254187.27.63.25516,382
110187.27.64.0/18187.27.64.1 to 187.27.127.254187.27.127.25516,382
111187.27.128.0/18187.27.128.1 to 187.27.191.254187.27.191.25516,382
112187.27.192.0/18187.27.192.1 to 187.27.255.254187.27.255.25516,382
113187.28.0.0/18187.28.0.1 to 187.28.63.254187.28.63.25516,382
114187.28.64.0/18187.28.64.1 to 187.28.127.254187.28.127.25516,382
115187.28.128.0/18187.28.128.1 to 187.28.191.254187.28.191.25516,382
116187.28.192.0/18187.28.192.1 to 187.28.255.254187.28.255.25516,382
117187.29.0.0/18187.29.0.1 to 187.29.63.254187.29.63.25516,382
118187.29.64.0/18187.29.64.1 to 187.29.127.254187.29.127.25516,382
119187.29.128.0/18187.29.128.1 to 187.29.191.254187.29.191.25516,382
120187.29.192.0/18187.29.192.1 to 187.29.255.254187.29.255.25516,382
121187.30.0.0/18187.30.0.1 to 187.30.63.254187.30.63.25516,382
122187.30.64.0/18187.30.64.1 to 187.30.127.254187.30.127.25516,382
123187.30.128.0/18187.30.128.1 to 187.30.191.254187.30.191.25516,382
124187.30.192.0/18187.30.192.1 to 187.30.255.254187.30.255.25516,382
125187.31.0.0/18187.31.0.1 to 187.31.63.254187.31.63.25516,382
126187.31.64.0/18187.31.64.1 to 187.31.127.254187.31.127.25516,382
127187.31.128.0/18187.31.128.1 to 187.31.191.254187.31.191.25516,382
128187.31.192.0/18187.31.192.1 to 187.31.255.254187.31.255.25516,382
129187.32.0.0/18187.32.0.1 to 187.32.63.254187.32.63.25516,382
130187.32.64.0/18187.32.64.1 to 187.32.127.254187.32.127.25516,382
131187.32.128.0/18187.32.128.1 to 187.32.191.254187.32.191.25516,382
132187.32.192.0/18187.32.192.1 to 187.32.255.254187.32.255.25516,382
133187.33.0.0/18187.33.0.1 to 187.33.63.254187.33.63.25516,382
134187.33.64.0/18187.33.64.1 to 187.33.127.254187.33.127.25516,382
135187.33.128.0/18187.33.128.1 to 187.33.191.254187.33.191.25516,382
136187.33.192.0/18187.33.192.1 to 187.33.255.254187.33.255.25516,382
137187.34.0.0/18187.34.0.1 to 187.34.63.254187.34.63.25516,382
138187.34.64.0/18187.34.64.1 to 187.34.127.254187.34.127.25516,382
139187.34.128.0/18187.34.128.1 to 187.34.191.254187.34.191.25516,382
140187.34.192.0/18187.34.192.1 to 187.34.255.254187.34.255.25516,382
141187.35.0.0/18187.35.0.1 to 187.35.63.254187.35.63.25516,382
142187.35.64.0/18187.35.64.1 to 187.35.127.254187.35.127.25516,382
143187.35.128.0/18187.35.128.1 to 187.35.191.254187.35.191.25516,382
144187.35.192.0/18187.35.192.1 to 187.35.255.254187.35.255.25516,382
145187.36.0.0/18187.36.0.1 to 187.36.63.254187.36.63.25516,382
146187.36.64.0/18187.36.64.1 to 187.36.127.254187.36.127.25516,382
147187.36.128.0/18187.36.128.1 to 187.36.191.254187.36.191.25516,382
148187.36.192.0/18187.36.192.1 to 187.36.255.254187.36.255.25516,382
149187.37.0.0/18187.37.0.1 to 187.37.63.254187.37.63.25516,382
150187.37.64.0/18187.37.64.1 to 187.37.127.254187.37.127.25516,382
151187.37.128.0/18187.37.128.1 to 187.37.191.254187.37.191.25516,382
152187.37.192.0/18187.37.192.1 to 187.37.255.254187.37.255.25516,382
153187.38.0.0/18187.38.0.1 to 187.38.63.254187.38.63.25516,382
154187.38.64.0/18187.38.64.1 to 187.38.127.254187.38.127.25516,382
155187.38.128.0/18187.38.128.1 to 187.38.191.254187.38.191.25516,382
156187.38.192.0/18187.38.192.1 to 187.38.255.254187.38.255.25516,382
157187.39.0.0/18187.39.0.1 to 187.39.63.254187.39.63.25516,382
158187.39.64.0/18187.39.64.1 to 187.39.127.254187.39.127.25516,382
159187.39.128.0/18187.39.128.1 to 187.39.191.254187.39.191.25516,382
160187.39.192.0/18187.39.192.1 to 187.39.255.254187.39.255.25516,382
161187.40.0.0/18187.40.0.1 to 187.40.63.254187.40.63.25516,382
162187.40.64.0/18187.40.64.1 to 187.40.127.254187.40.127.25516,382
163187.40.128.0/18187.40.128.1 to 187.40.191.254187.40.191.25516,382
164187.40.192.0/18187.40.192.1 to 187.40.255.254187.40.255.25516,382
165187.41.0.0/18187.41.0.1 to 187.41.63.254187.41.63.25516,382
166187.41.64.0/18187.41.64.1 to 187.41.127.254187.41.127.25516,382
167187.41.128.0/18187.41.128.1 to 187.41.191.254187.41.191.25516,382
168187.41.192.0/18187.41.192.1 to 187.41.255.254187.41.255.25516,382
169187.42.0.0/18187.42.0.1 to 187.42.63.254187.42.63.25516,382
170187.42.64.0/18187.42.64.1 to 187.42.127.254187.42.127.25516,382
171187.42.128.0/18187.42.128.1 to 187.42.191.254187.42.191.25516,382
172187.42.192.0/18187.42.192.1 to 187.42.255.254187.42.255.25516,382
173187.43.0.0/18187.43.0.1 to 187.43.63.254187.43.63.25516,382
174187.43.64.0/18187.43.64.1 to 187.43.127.254187.43.127.25516,382
175187.43.128.0/18187.43.128.1 to 187.43.191.254187.43.191.25516,382
176187.43.192.0/18187.43.192.1 to 187.43.255.254187.43.255.25516,382
177187.44.0.0/18187.44.0.1 to 187.44.63.254187.44.63.25516,382
178187.44.64.0/18187.44.64.1 to 187.44.127.254187.44.127.25516,382
179187.44.128.0/18187.44.128.1 to 187.44.191.254187.44.191.25516,382
180187.44.192.0/18187.44.192.1 to 187.44.255.254187.44.255.25516,382
181187.45.0.0/18187.45.0.1 to 187.45.63.254187.45.63.25516,382
182187.45.64.0/18187.45.64.1 to 187.45.127.254187.45.127.25516,382
183187.45.128.0/18187.45.128.1 to 187.45.191.254187.45.191.25516,382
184187.45.192.0/18187.45.192.1 to 187.45.255.254187.45.255.25516,382
185187.46.0.0/18187.46.0.1 to 187.46.63.254187.46.63.25516,382
186187.46.64.0/18187.46.64.1 to 187.46.127.254187.46.127.25516,382
187187.46.128.0/18187.46.128.1 to 187.46.191.254187.46.191.25516,382
188187.46.192.0/18187.46.192.1 to 187.46.255.254187.46.255.25516,382
189187.47.0.0/18187.47.0.1 to 187.47.63.254187.47.63.25516,382
190187.47.64.0/18187.47.64.1 to 187.47.127.254187.47.127.25516,382
191187.47.128.0/18187.47.128.1 to 187.47.191.254187.47.191.25516,382
192187.47.192.0/18187.47.192.1 to 187.47.255.254187.47.255.25516,382
193187.48.0.0/18187.48.0.1 to 187.48.63.254187.48.63.25516,382
194187.48.64.0/18187.48.64.1 to 187.48.127.254187.48.127.25516,382
195187.48.128.0/18187.48.128.1 to 187.48.191.254187.48.191.25516,382
196187.48.192.0/18187.48.192.1 to 187.48.255.254187.48.255.25516,382
197187.49.0.0/18187.49.0.1 to 187.49.63.254187.49.63.25516,382
198187.49.64.0/18187.49.64.1 to 187.49.127.254187.49.127.25516,382
199187.49.128.0/18187.49.128.1 to 187.49.191.254187.49.191.25516,382
200187.49.192.0/18187.49.192.1 to 187.49.255.254187.49.255.25516,382
201187.50.0.0/18187.50.0.1 to 187.50.63.254187.50.63.25516,382
202187.50.64.0/18187.50.64.1 to 187.50.127.254187.50.127.25516,382
203187.50.128.0/18187.50.128.1 to 187.50.191.254187.50.191.25516,382
204187.50.192.0/18187.50.192.1 to 187.50.255.254187.50.255.25516,382
205187.51.0.0/18187.51.0.1 to 187.51.63.254187.51.63.25516,382
206187.51.64.0/18187.51.64.1 to 187.51.127.254187.51.127.25516,382
207187.51.128.0/18187.51.128.1 to 187.51.191.254187.51.191.25516,382
208187.51.192.0/18187.51.192.1 to 187.51.255.254187.51.255.25516,382
209187.52.0.0/18187.52.0.1 to 187.52.63.254187.52.63.25516,382
210187.52.64.0/18187.52.64.1 to 187.52.127.254187.52.127.25516,382
211187.52.128.0/18187.52.128.1 to 187.52.191.254187.52.191.25516,382
212187.52.192.0/18187.52.192.1 to 187.52.255.254187.52.255.25516,382
213187.53.0.0/18187.53.0.1 to 187.53.63.254187.53.63.25516,382
214187.53.64.0/18187.53.64.1 to 187.53.127.254187.53.127.25516,382
215187.53.128.0/18187.53.128.1 to 187.53.191.254187.53.191.25516,382
216187.53.192.0/18187.53.192.1 to 187.53.255.254187.53.255.25516,382
217187.54.0.0/18187.54.0.1 to 187.54.63.254187.54.63.25516,382
218187.54.64.0/18187.54.64.1 to 187.54.127.254187.54.127.25516,382
219187.54.128.0/18187.54.128.1 to 187.54.191.254187.54.191.25516,382
220187.54.192.0/18187.54.192.1 to 187.54.255.254187.54.255.25516,382
221187.55.0.0/18187.55.0.1 to 187.55.63.254187.55.63.25516,382
222187.55.64.0/18187.55.64.1 to 187.55.127.254187.55.127.25516,382
223187.55.128.0/18187.55.128.1 to 187.55.191.254187.55.191.25516,382
224187.55.192.0/18187.55.192.1 to 187.55.255.254187.55.255.25516,382
225187.56.0.0/18187.56.0.1 to 187.56.63.254187.56.63.25516,382
226187.56.64.0/18187.56.64.1 to 187.56.127.254187.56.127.25516,382
227187.56.128.0/18187.56.128.1 to 187.56.191.254187.56.191.25516,382
228187.56.192.0/18187.56.192.1 to 187.56.255.254187.56.255.25516,382
229187.57.0.0/18187.57.0.1 to 187.57.63.254187.57.63.25516,382
230187.57.64.0/18187.57.64.1 to 187.57.127.254187.57.127.25516,382
231187.57.128.0/18187.57.128.1 to 187.57.191.254187.57.191.25516,382
232187.57.192.0/18187.57.192.1 to 187.57.255.254187.57.255.25516,382
233187.58.0.0/18187.58.0.1 to 187.58.63.254187.58.63.25516,382
234187.58.64.0/18187.58.64.1 to 187.58.127.254187.58.127.25516,382
235187.58.128.0/18187.58.128.1 to 187.58.191.254187.58.191.25516,382
236187.58.192.0/18187.58.192.1 to 187.58.255.254187.58.255.25516,382
237187.59.0.0/18187.59.0.1 to 187.59.63.254187.59.63.25516,382
238187.59.64.0/18187.59.64.1 to 187.59.127.254187.59.127.25516,382
239187.59.128.0/18187.59.128.1 to 187.59.191.254187.59.191.25516,382
240187.59.192.0/18187.59.192.1 to 187.59.255.254187.59.255.25516,382
241187.60.0.0/18187.60.0.1 to 187.60.63.254187.60.63.25516,382
242187.60.64.0/18187.60.64.1 to 187.60.127.254187.60.127.25516,382
243187.60.128.0/18187.60.128.1 to 187.60.191.254187.60.191.25516,382
244187.60.192.0/18187.60.192.1 to 187.60.255.254187.60.255.25516,382
245187.61.0.0/18187.61.0.1 to 187.61.63.254187.61.63.25516,382
246187.61.64.0/18187.61.64.1 to 187.61.127.254187.61.127.25516,382
247187.61.128.0/18187.61.128.1 to 187.61.191.254187.61.191.25516,382
248187.61.192.0/18187.61.192.1 to 187.61.255.254187.61.255.25516,382
249187.62.0.0/18187.62.0.1 to 187.62.63.254187.62.63.25516,382
250187.62.64.0/18187.62.64.1 to 187.62.127.254187.62.127.25516,382
251187.62.128.0/18187.62.128.1 to 187.62.191.254187.62.191.25516,382
252187.62.192.0/18187.62.192.1 to 187.62.255.254187.62.255.25516,382
253187.63.0.0/18187.63.0.1 to 187.63.63.254187.63.63.25516,382
254187.63.64.0/18187.63.64.1 to 187.63.127.254187.63.127.25516,382
255187.63.128.0/18187.63.128.1 to 187.63.191.254187.63.191.25516,382
256187.63.192.0/18187.63.192.1 to 187.63.255.254187.63.255.25516,382

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.