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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.

Network191.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
191.0.0.0
Broadcast address
191.255.255.255
First usable
191.0.0.1
Last usable
191.255.255.254
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 BF000000 · Integer 3204448256 to 3221225471
Reverse DNS zone
191.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10111111..00000000.00000000.00000000191.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network10111111..00000000.00000000.00000000191.0.0.0
Broadcast10111111..11111111.11111111.11111111191.255.255.255
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)

191.0.0.0/8 makes 1,024 subnets of /18; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1191.0.0.0/18191.0.0.1 to 191.0.63.254191.0.63.25516,382
2191.0.64.0/18191.0.64.1 to 191.0.127.254191.0.127.25516,382
3191.0.128.0/18191.0.128.1 to 191.0.191.254191.0.191.25516,382
4191.0.192.0/18191.0.192.1 to 191.0.255.254191.0.255.25516,382
5191.1.0.0/18191.1.0.1 to 191.1.63.254191.1.63.25516,382
6191.1.64.0/18191.1.64.1 to 191.1.127.254191.1.127.25516,382
7191.1.128.0/18191.1.128.1 to 191.1.191.254191.1.191.25516,382
8191.1.192.0/18191.1.192.1 to 191.1.255.254191.1.255.25516,382
9191.2.0.0/18191.2.0.1 to 191.2.63.254191.2.63.25516,382
10191.2.64.0/18191.2.64.1 to 191.2.127.254191.2.127.25516,382
11191.2.128.0/18191.2.128.1 to 191.2.191.254191.2.191.25516,382
12191.2.192.0/18191.2.192.1 to 191.2.255.254191.2.255.25516,382
13191.3.0.0/18191.3.0.1 to 191.3.63.254191.3.63.25516,382
14191.3.64.0/18191.3.64.1 to 191.3.127.254191.3.127.25516,382
15191.3.128.0/18191.3.128.1 to 191.3.191.254191.3.191.25516,382
16191.3.192.0/18191.3.192.1 to 191.3.255.254191.3.255.25516,382
17191.4.0.0/18191.4.0.1 to 191.4.63.254191.4.63.25516,382
18191.4.64.0/18191.4.64.1 to 191.4.127.254191.4.127.25516,382
19191.4.128.0/18191.4.128.1 to 191.4.191.254191.4.191.25516,382
20191.4.192.0/18191.4.192.1 to 191.4.255.254191.4.255.25516,382
21191.5.0.0/18191.5.0.1 to 191.5.63.254191.5.63.25516,382
22191.5.64.0/18191.5.64.1 to 191.5.127.254191.5.127.25516,382
23191.5.128.0/18191.5.128.1 to 191.5.191.254191.5.191.25516,382
24191.5.192.0/18191.5.192.1 to 191.5.255.254191.5.255.25516,382
25191.6.0.0/18191.6.0.1 to 191.6.63.254191.6.63.25516,382
26191.6.64.0/18191.6.64.1 to 191.6.127.254191.6.127.25516,382
27191.6.128.0/18191.6.128.1 to 191.6.191.254191.6.191.25516,382
28191.6.192.0/18191.6.192.1 to 191.6.255.254191.6.255.25516,382
29191.7.0.0/18191.7.0.1 to 191.7.63.254191.7.63.25516,382
30191.7.64.0/18191.7.64.1 to 191.7.127.254191.7.127.25516,382
31191.7.128.0/18191.7.128.1 to 191.7.191.254191.7.191.25516,382
32191.7.192.0/18191.7.192.1 to 191.7.255.254191.7.255.25516,382
33191.8.0.0/18191.8.0.1 to 191.8.63.254191.8.63.25516,382
34191.8.64.0/18191.8.64.1 to 191.8.127.254191.8.127.25516,382
35191.8.128.0/18191.8.128.1 to 191.8.191.254191.8.191.25516,382
36191.8.192.0/18191.8.192.1 to 191.8.255.254191.8.255.25516,382
37191.9.0.0/18191.9.0.1 to 191.9.63.254191.9.63.25516,382
38191.9.64.0/18191.9.64.1 to 191.9.127.254191.9.127.25516,382
39191.9.128.0/18191.9.128.1 to 191.9.191.254191.9.191.25516,382
40191.9.192.0/18191.9.192.1 to 191.9.255.254191.9.255.25516,382
41191.10.0.0/18191.10.0.1 to 191.10.63.254191.10.63.25516,382
42191.10.64.0/18191.10.64.1 to 191.10.127.254191.10.127.25516,382
43191.10.128.0/18191.10.128.1 to 191.10.191.254191.10.191.25516,382
44191.10.192.0/18191.10.192.1 to 191.10.255.254191.10.255.25516,382
45191.11.0.0/18191.11.0.1 to 191.11.63.254191.11.63.25516,382
46191.11.64.0/18191.11.64.1 to 191.11.127.254191.11.127.25516,382
47191.11.128.0/18191.11.128.1 to 191.11.191.254191.11.191.25516,382
48191.11.192.0/18191.11.192.1 to 191.11.255.254191.11.255.25516,382
49191.12.0.0/18191.12.0.1 to 191.12.63.254191.12.63.25516,382
50191.12.64.0/18191.12.64.1 to 191.12.127.254191.12.127.25516,382
51191.12.128.0/18191.12.128.1 to 191.12.191.254191.12.191.25516,382
52191.12.192.0/18191.12.192.1 to 191.12.255.254191.12.255.25516,382
53191.13.0.0/18191.13.0.1 to 191.13.63.254191.13.63.25516,382
54191.13.64.0/18191.13.64.1 to 191.13.127.254191.13.127.25516,382
55191.13.128.0/18191.13.128.1 to 191.13.191.254191.13.191.25516,382
56191.13.192.0/18191.13.192.1 to 191.13.255.254191.13.255.25516,382
57191.14.0.0/18191.14.0.1 to 191.14.63.254191.14.63.25516,382
58191.14.64.0/18191.14.64.1 to 191.14.127.254191.14.127.25516,382
59191.14.128.0/18191.14.128.1 to 191.14.191.254191.14.191.25516,382
60191.14.192.0/18191.14.192.1 to 191.14.255.254191.14.255.25516,382
61191.15.0.0/18191.15.0.1 to 191.15.63.254191.15.63.25516,382
62191.15.64.0/18191.15.64.1 to 191.15.127.254191.15.127.25516,382
63191.15.128.0/18191.15.128.1 to 191.15.191.254191.15.191.25516,382
64191.15.192.0/18191.15.192.1 to 191.15.255.254191.15.255.25516,382
65191.16.0.0/18191.16.0.1 to 191.16.63.254191.16.63.25516,382
66191.16.64.0/18191.16.64.1 to 191.16.127.254191.16.127.25516,382
67191.16.128.0/18191.16.128.1 to 191.16.191.254191.16.191.25516,382
68191.16.192.0/18191.16.192.1 to 191.16.255.254191.16.255.25516,382
69191.17.0.0/18191.17.0.1 to 191.17.63.254191.17.63.25516,382
70191.17.64.0/18191.17.64.1 to 191.17.127.254191.17.127.25516,382
71191.17.128.0/18191.17.128.1 to 191.17.191.254191.17.191.25516,382
72191.17.192.0/18191.17.192.1 to 191.17.255.254191.17.255.25516,382
73191.18.0.0/18191.18.0.1 to 191.18.63.254191.18.63.25516,382
74191.18.64.0/18191.18.64.1 to 191.18.127.254191.18.127.25516,382
75191.18.128.0/18191.18.128.1 to 191.18.191.254191.18.191.25516,382
76191.18.192.0/18191.18.192.1 to 191.18.255.254191.18.255.25516,382
77191.19.0.0/18191.19.0.1 to 191.19.63.254191.19.63.25516,382
78191.19.64.0/18191.19.64.1 to 191.19.127.254191.19.127.25516,382
79191.19.128.0/18191.19.128.1 to 191.19.191.254191.19.191.25516,382
80191.19.192.0/18191.19.192.1 to 191.19.255.254191.19.255.25516,382
81191.20.0.0/18191.20.0.1 to 191.20.63.254191.20.63.25516,382
82191.20.64.0/18191.20.64.1 to 191.20.127.254191.20.127.25516,382
83191.20.128.0/18191.20.128.1 to 191.20.191.254191.20.191.25516,382
84191.20.192.0/18191.20.192.1 to 191.20.255.254191.20.255.25516,382
85191.21.0.0/18191.21.0.1 to 191.21.63.254191.21.63.25516,382
86191.21.64.0/18191.21.64.1 to 191.21.127.254191.21.127.25516,382
87191.21.128.0/18191.21.128.1 to 191.21.191.254191.21.191.25516,382
88191.21.192.0/18191.21.192.1 to 191.21.255.254191.21.255.25516,382
89191.22.0.0/18191.22.0.1 to 191.22.63.254191.22.63.25516,382
90191.22.64.0/18191.22.64.1 to 191.22.127.254191.22.127.25516,382
91191.22.128.0/18191.22.128.1 to 191.22.191.254191.22.191.25516,382
92191.22.192.0/18191.22.192.1 to 191.22.255.254191.22.255.25516,382
93191.23.0.0/18191.23.0.1 to 191.23.63.254191.23.63.25516,382
94191.23.64.0/18191.23.64.1 to 191.23.127.254191.23.127.25516,382
95191.23.128.0/18191.23.128.1 to 191.23.191.254191.23.191.25516,382
96191.23.192.0/18191.23.192.1 to 191.23.255.254191.23.255.25516,382
97191.24.0.0/18191.24.0.1 to 191.24.63.254191.24.63.25516,382
98191.24.64.0/18191.24.64.1 to 191.24.127.254191.24.127.25516,382
99191.24.128.0/18191.24.128.1 to 191.24.191.254191.24.191.25516,382
100191.24.192.0/18191.24.192.1 to 191.24.255.254191.24.255.25516,382
101191.25.0.0/18191.25.0.1 to 191.25.63.254191.25.63.25516,382
102191.25.64.0/18191.25.64.1 to 191.25.127.254191.25.127.25516,382
103191.25.128.0/18191.25.128.1 to 191.25.191.254191.25.191.25516,382
104191.25.192.0/18191.25.192.1 to 191.25.255.254191.25.255.25516,382
105191.26.0.0/18191.26.0.1 to 191.26.63.254191.26.63.25516,382
106191.26.64.0/18191.26.64.1 to 191.26.127.254191.26.127.25516,382
107191.26.128.0/18191.26.128.1 to 191.26.191.254191.26.191.25516,382
108191.26.192.0/18191.26.192.1 to 191.26.255.254191.26.255.25516,382
109191.27.0.0/18191.27.0.1 to 191.27.63.254191.27.63.25516,382
110191.27.64.0/18191.27.64.1 to 191.27.127.254191.27.127.25516,382
111191.27.128.0/18191.27.128.1 to 191.27.191.254191.27.191.25516,382
112191.27.192.0/18191.27.192.1 to 191.27.255.254191.27.255.25516,382
113191.28.0.0/18191.28.0.1 to 191.28.63.254191.28.63.25516,382
114191.28.64.0/18191.28.64.1 to 191.28.127.254191.28.127.25516,382
115191.28.128.0/18191.28.128.1 to 191.28.191.254191.28.191.25516,382
116191.28.192.0/18191.28.192.1 to 191.28.255.254191.28.255.25516,382
117191.29.0.0/18191.29.0.1 to 191.29.63.254191.29.63.25516,382
118191.29.64.0/18191.29.64.1 to 191.29.127.254191.29.127.25516,382
119191.29.128.0/18191.29.128.1 to 191.29.191.254191.29.191.25516,382
120191.29.192.0/18191.29.192.1 to 191.29.255.254191.29.255.25516,382
121191.30.0.0/18191.30.0.1 to 191.30.63.254191.30.63.25516,382
122191.30.64.0/18191.30.64.1 to 191.30.127.254191.30.127.25516,382
123191.30.128.0/18191.30.128.1 to 191.30.191.254191.30.191.25516,382
124191.30.192.0/18191.30.192.1 to 191.30.255.254191.30.255.25516,382
125191.31.0.0/18191.31.0.1 to 191.31.63.254191.31.63.25516,382
126191.31.64.0/18191.31.64.1 to 191.31.127.254191.31.127.25516,382
127191.31.128.0/18191.31.128.1 to 191.31.191.254191.31.191.25516,382
128191.31.192.0/18191.31.192.1 to 191.31.255.254191.31.255.25516,382
129191.32.0.0/18191.32.0.1 to 191.32.63.254191.32.63.25516,382
130191.32.64.0/18191.32.64.1 to 191.32.127.254191.32.127.25516,382
131191.32.128.0/18191.32.128.1 to 191.32.191.254191.32.191.25516,382
132191.32.192.0/18191.32.192.1 to 191.32.255.254191.32.255.25516,382
133191.33.0.0/18191.33.0.1 to 191.33.63.254191.33.63.25516,382
134191.33.64.0/18191.33.64.1 to 191.33.127.254191.33.127.25516,382
135191.33.128.0/18191.33.128.1 to 191.33.191.254191.33.191.25516,382
136191.33.192.0/18191.33.192.1 to 191.33.255.254191.33.255.25516,382
137191.34.0.0/18191.34.0.1 to 191.34.63.254191.34.63.25516,382
138191.34.64.0/18191.34.64.1 to 191.34.127.254191.34.127.25516,382
139191.34.128.0/18191.34.128.1 to 191.34.191.254191.34.191.25516,382
140191.34.192.0/18191.34.192.1 to 191.34.255.254191.34.255.25516,382
141191.35.0.0/18191.35.0.1 to 191.35.63.254191.35.63.25516,382
142191.35.64.0/18191.35.64.1 to 191.35.127.254191.35.127.25516,382
143191.35.128.0/18191.35.128.1 to 191.35.191.254191.35.191.25516,382
144191.35.192.0/18191.35.192.1 to 191.35.255.254191.35.255.25516,382
145191.36.0.0/18191.36.0.1 to 191.36.63.254191.36.63.25516,382
146191.36.64.0/18191.36.64.1 to 191.36.127.254191.36.127.25516,382
147191.36.128.0/18191.36.128.1 to 191.36.191.254191.36.191.25516,382
148191.36.192.0/18191.36.192.1 to 191.36.255.254191.36.255.25516,382
149191.37.0.0/18191.37.0.1 to 191.37.63.254191.37.63.25516,382
150191.37.64.0/18191.37.64.1 to 191.37.127.254191.37.127.25516,382
151191.37.128.0/18191.37.128.1 to 191.37.191.254191.37.191.25516,382
152191.37.192.0/18191.37.192.1 to 191.37.255.254191.37.255.25516,382
153191.38.0.0/18191.38.0.1 to 191.38.63.254191.38.63.25516,382
154191.38.64.0/18191.38.64.1 to 191.38.127.254191.38.127.25516,382
155191.38.128.0/18191.38.128.1 to 191.38.191.254191.38.191.25516,382
156191.38.192.0/18191.38.192.1 to 191.38.255.254191.38.255.25516,382
157191.39.0.0/18191.39.0.1 to 191.39.63.254191.39.63.25516,382
158191.39.64.0/18191.39.64.1 to 191.39.127.254191.39.127.25516,382
159191.39.128.0/18191.39.128.1 to 191.39.191.254191.39.191.25516,382
160191.39.192.0/18191.39.192.1 to 191.39.255.254191.39.255.25516,382
161191.40.0.0/18191.40.0.1 to 191.40.63.254191.40.63.25516,382
162191.40.64.0/18191.40.64.1 to 191.40.127.254191.40.127.25516,382
163191.40.128.0/18191.40.128.1 to 191.40.191.254191.40.191.25516,382
164191.40.192.0/18191.40.192.1 to 191.40.255.254191.40.255.25516,382
165191.41.0.0/18191.41.0.1 to 191.41.63.254191.41.63.25516,382
166191.41.64.0/18191.41.64.1 to 191.41.127.254191.41.127.25516,382
167191.41.128.0/18191.41.128.1 to 191.41.191.254191.41.191.25516,382
168191.41.192.0/18191.41.192.1 to 191.41.255.254191.41.255.25516,382
169191.42.0.0/18191.42.0.1 to 191.42.63.254191.42.63.25516,382
170191.42.64.0/18191.42.64.1 to 191.42.127.254191.42.127.25516,382
171191.42.128.0/18191.42.128.1 to 191.42.191.254191.42.191.25516,382
172191.42.192.0/18191.42.192.1 to 191.42.255.254191.42.255.25516,382
173191.43.0.0/18191.43.0.1 to 191.43.63.254191.43.63.25516,382
174191.43.64.0/18191.43.64.1 to 191.43.127.254191.43.127.25516,382
175191.43.128.0/18191.43.128.1 to 191.43.191.254191.43.191.25516,382
176191.43.192.0/18191.43.192.1 to 191.43.255.254191.43.255.25516,382
177191.44.0.0/18191.44.0.1 to 191.44.63.254191.44.63.25516,382
178191.44.64.0/18191.44.64.1 to 191.44.127.254191.44.127.25516,382
179191.44.128.0/18191.44.128.1 to 191.44.191.254191.44.191.25516,382
180191.44.192.0/18191.44.192.1 to 191.44.255.254191.44.255.25516,382
181191.45.0.0/18191.45.0.1 to 191.45.63.254191.45.63.25516,382
182191.45.64.0/18191.45.64.1 to 191.45.127.254191.45.127.25516,382
183191.45.128.0/18191.45.128.1 to 191.45.191.254191.45.191.25516,382
184191.45.192.0/18191.45.192.1 to 191.45.255.254191.45.255.25516,382
185191.46.0.0/18191.46.0.1 to 191.46.63.254191.46.63.25516,382
186191.46.64.0/18191.46.64.1 to 191.46.127.254191.46.127.25516,382
187191.46.128.0/18191.46.128.1 to 191.46.191.254191.46.191.25516,382
188191.46.192.0/18191.46.192.1 to 191.46.255.254191.46.255.25516,382
189191.47.0.0/18191.47.0.1 to 191.47.63.254191.47.63.25516,382
190191.47.64.0/18191.47.64.1 to 191.47.127.254191.47.127.25516,382
191191.47.128.0/18191.47.128.1 to 191.47.191.254191.47.191.25516,382
192191.47.192.0/18191.47.192.1 to 191.47.255.254191.47.255.25516,382
193191.48.0.0/18191.48.0.1 to 191.48.63.254191.48.63.25516,382
194191.48.64.0/18191.48.64.1 to 191.48.127.254191.48.127.25516,382
195191.48.128.0/18191.48.128.1 to 191.48.191.254191.48.191.25516,382
196191.48.192.0/18191.48.192.1 to 191.48.255.254191.48.255.25516,382
197191.49.0.0/18191.49.0.1 to 191.49.63.254191.49.63.25516,382
198191.49.64.0/18191.49.64.1 to 191.49.127.254191.49.127.25516,382
199191.49.128.0/18191.49.128.1 to 191.49.191.254191.49.191.25516,382
200191.49.192.0/18191.49.192.1 to 191.49.255.254191.49.255.25516,382
201191.50.0.0/18191.50.0.1 to 191.50.63.254191.50.63.25516,382
202191.50.64.0/18191.50.64.1 to 191.50.127.254191.50.127.25516,382
203191.50.128.0/18191.50.128.1 to 191.50.191.254191.50.191.25516,382
204191.50.192.0/18191.50.192.1 to 191.50.255.254191.50.255.25516,382
205191.51.0.0/18191.51.0.1 to 191.51.63.254191.51.63.25516,382
206191.51.64.0/18191.51.64.1 to 191.51.127.254191.51.127.25516,382
207191.51.128.0/18191.51.128.1 to 191.51.191.254191.51.191.25516,382
208191.51.192.0/18191.51.192.1 to 191.51.255.254191.51.255.25516,382
209191.52.0.0/18191.52.0.1 to 191.52.63.254191.52.63.25516,382
210191.52.64.0/18191.52.64.1 to 191.52.127.254191.52.127.25516,382
211191.52.128.0/18191.52.128.1 to 191.52.191.254191.52.191.25516,382
212191.52.192.0/18191.52.192.1 to 191.52.255.254191.52.255.25516,382
213191.53.0.0/18191.53.0.1 to 191.53.63.254191.53.63.25516,382
214191.53.64.0/18191.53.64.1 to 191.53.127.254191.53.127.25516,382
215191.53.128.0/18191.53.128.1 to 191.53.191.254191.53.191.25516,382
216191.53.192.0/18191.53.192.1 to 191.53.255.254191.53.255.25516,382
217191.54.0.0/18191.54.0.1 to 191.54.63.254191.54.63.25516,382
218191.54.64.0/18191.54.64.1 to 191.54.127.254191.54.127.25516,382
219191.54.128.0/18191.54.128.1 to 191.54.191.254191.54.191.25516,382
220191.54.192.0/18191.54.192.1 to 191.54.255.254191.54.255.25516,382
221191.55.0.0/18191.55.0.1 to 191.55.63.254191.55.63.25516,382
222191.55.64.0/18191.55.64.1 to 191.55.127.254191.55.127.25516,382
223191.55.128.0/18191.55.128.1 to 191.55.191.254191.55.191.25516,382
224191.55.192.0/18191.55.192.1 to 191.55.255.254191.55.255.25516,382
225191.56.0.0/18191.56.0.1 to 191.56.63.254191.56.63.25516,382
226191.56.64.0/18191.56.64.1 to 191.56.127.254191.56.127.25516,382
227191.56.128.0/18191.56.128.1 to 191.56.191.254191.56.191.25516,382
228191.56.192.0/18191.56.192.1 to 191.56.255.254191.56.255.25516,382
229191.57.0.0/18191.57.0.1 to 191.57.63.254191.57.63.25516,382
230191.57.64.0/18191.57.64.1 to 191.57.127.254191.57.127.25516,382
231191.57.128.0/18191.57.128.1 to 191.57.191.254191.57.191.25516,382
232191.57.192.0/18191.57.192.1 to 191.57.255.254191.57.255.25516,382
233191.58.0.0/18191.58.0.1 to 191.58.63.254191.58.63.25516,382
234191.58.64.0/18191.58.64.1 to 191.58.127.254191.58.127.25516,382
235191.58.128.0/18191.58.128.1 to 191.58.191.254191.58.191.25516,382
236191.58.192.0/18191.58.192.1 to 191.58.255.254191.58.255.25516,382
237191.59.0.0/18191.59.0.1 to 191.59.63.254191.59.63.25516,382
238191.59.64.0/18191.59.64.1 to 191.59.127.254191.59.127.25516,382
239191.59.128.0/18191.59.128.1 to 191.59.191.254191.59.191.25516,382
240191.59.192.0/18191.59.192.1 to 191.59.255.254191.59.255.25516,382
241191.60.0.0/18191.60.0.1 to 191.60.63.254191.60.63.25516,382
242191.60.64.0/18191.60.64.1 to 191.60.127.254191.60.127.25516,382
243191.60.128.0/18191.60.128.1 to 191.60.191.254191.60.191.25516,382
244191.60.192.0/18191.60.192.1 to 191.60.255.254191.60.255.25516,382
245191.61.0.0/18191.61.0.1 to 191.61.63.254191.61.63.25516,382
246191.61.64.0/18191.61.64.1 to 191.61.127.254191.61.127.25516,382
247191.61.128.0/18191.61.128.1 to 191.61.191.254191.61.191.25516,382
248191.61.192.0/18191.61.192.1 to 191.61.255.254191.61.255.25516,382
249191.62.0.0/18191.62.0.1 to 191.62.63.254191.62.63.25516,382
250191.62.64.0/18191.62.64.1 to 191.62.127.254191.62.127.25516,382
251191.62.128.0/18191.62.128.1 to 191.62.191.254191.62.191.25516,382
252191.62.192.0/18191.62.192.1 to 191.62.255.254191.62.255.25516,382
253191.63.0.0/18191.63.0.1 to 191.63.63.254191.63.63.25516,382
254191.63.64.0/18191.63.64.1 to 191.63.127.254191.63.127.25516,382
255191.63.128.0/18191.63.128.1 to 191.63.191.254191.63.191.25516,382
256191.63.192.0/18191.63.192.1 to 191.63.255.254191.63.255.25516,382

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.