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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.

Network181.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
181.0.0.0
Broadcast address
181.255.255.255
First usable
181.0.0.1
Last usable
181.255.255.254
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 B5000000 · Integer 3036676096 to 3053453311
Reverse DNS zone
181.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10110101..00000000.00000000.00000000181.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network10110101..00000000.00000000.00000000181.0.0.0
Broadcast10110101..11111111.11111111.11111111181.255.255.255
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)

181.0.0.0/8 makes 1,024 subnets of /18; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1181.0.0.0/18181.0.0.1 to 181.0.63.254181.0.63.25516,382
2181.0.64.0/18181.0.64.1 to 181.0.127.254181.0.127.25516,382
3181.0.128.0/18181.0.128.1 to 181.0.191.254181.0.191.25516,382
4181.0.192.0/18181.0.192.1 to 181.0.255.254181.0.255.25516,382
5181.1.0.0/18181.1.0.1 to 181.1.63.254181.1.63.25516,382
6181.1.64.0/18181.1.64.1 to 181.1.127.254181.1.127.25516,382
7181.1.128.0/18181.1.128.1 to 181.1.191.254181.1.191.25516,382
8181.1.192.0/18181.1.192.1 to 181.1.255.254181.1.255.25516,382
9181.2.0.0/18181.2.0.1 to 181.2.63.254181.2.63.25516,382
10181.2.64.0/18181.2.64.1 to 181.2.127.254181.2.127.25516,382
11181.2.128.0/18181.2.128.1 to 181.2.191.254181.2.191.25516,382
12181.2.192.0/18181.2.192.1 to 181.2.255.254181.2.255.25516,382
13181.3.0.0/18181.3.0.1 to 181.3.63.254181.3.63.25516,382
14181.3.64.0/18181.3.64.1 to 181.3.127.254181.3.127.25516,382
15181.3.128.0/18181.3.128.1 to 181.3.191.254181.3.191.25516,382
16181.3.192.0/18181.3.192.1 to 181.3.255.254181.3.255.25516,382
17181.4.0.0/18181.4.0.1 to 181.4.63.254181.4.63.25516,382
18181.4.64.0/18181.4.64.1 to 181.4.127.254181.4.127.25516,382
19181.4.128.0/18181.4.128.1 to 181.4.191.254181.4.191.25516,382
20181.4.192.0/18181.4.192.1 to 181.4.255.254181.4.255.25516,382
21181.5.0.0/18181.5.0.1 to 181.5.63.254181.5.63.25516,382
22181.5.64.0/18181.5.64.1 to 181.5.127.254181.5.127.25516,382
23181.5.128.0/18181.5.128.1 to 181.5.191.254181.5.191.25516,382
24181.5.192.0/18181.5.192.1 to 181.5.255.254181.5.255.25516,382
25181.6.0.0/18181.6.0.1 to 181.6.63.254181.6.63.25516,382
26181.6.64.0/18181.6.64.1 to 181.6.127.254181.6.127.25516,382
27181.6.128.0/18181.6.128.1 to 181.6.191.254181.6.191.25516,382
28181.6.192.0/18181.6.192.1 to 181.6.255.254181.6.255.25516,382
29181.7.0.0/18181.7.0.1 to 181.7.63.254181.7.63.25516,382
30181.7.64.0/18181.7.64.1 to 181.7.127.254181.7.127.25516,382
31181.7.128.0/18181.7.128.1 to 181.7.191.254181.7.191.25516,382
32181.7.192.0/18181.7.192.1 to 181.7.255.254181.7.255.25516,382
33181.8.0.0/18181.8.0.1 to 181.8.63.254181.8.63.25516,382
34181.8.64.0/18181.8.64.1 to 181.8.127.254181.8.127.25516,382
35181.8.128.0/18181.8.128.1 to 181.8.191.254181.8.191.25516,382
36181.8.192.0/18181.8.192.1 to 181.8.255.254181.8.255.25516,382
37181.9.0.0/18181.9.0.1 to 181.9.63.254181.9.63.25516,382
38181.9.64.0/18181.9.64.1 to 181.9.127.254181.9.127.25516,382
39181.9.128.0/18181.9.128.1 to 181.9.191.254181.9.191.25516,382
40181.9.192.0/18181.9.192.1 to 181.9.255.254181.9.255.25516,382
41181.10.0.0/18181.10.0.1 to 181.10.63.254181.10.63.25516,382
42181.10.64.0/18181.10.64.1 to 181.10.127.254181.10.127.25516,382
43181.10.128.0/18181.10.128.1 to 181.10.191.254181.10.191.25516,382
44181.10.192.0/18181.10.192.1 to 181.10.255.254181.10.255.25516,382
45181.11.0.0/18181.11.0.1 to 181.11.63.254181.11.63.25516,382
46181.11.64.0/18181.11.64.1 to 181.11.127.254181.11.127.25516,382
47181.11.128.0/18181.11.128.1 to 181.11.191.254181.11.191.25516,382
48181.11.192.0/18181.11.192.1 to 181.11.255.254181.11.255.25516,382
49181.12.0.0/18181.12.0.1 to 181.12.63.254181.12.63.25516,382
50181.12.64.0/18181.12.64.1 to 181.12.127.254181.12.127.25516,382
51181.12.128.0/18181.12.128.1 to 181.12.191.254181.12.191.25516,382
52181.12.192.0/18181.12.192.1 to 181.12.255.254181.12.255.25516,382
53181.13.0.0/18181.13.0.1 to 181.13.63.254181.13.63.25516,382
54181.13.64.0/18181.13.64.1 to 181.13.127.254181.13.127.25516,382
55181.13.128.0/18181.13.128.1 to 181.13.191.254181.13.191.25516,382
56181.13.192.0/18181.13.192.1 to 181.13.255.254181.13.255.25516,382
57181.14.0.0/18181.14.0.1 to 181.14.63.254181.14.63.25516,382
58181.14.64.0/18181.14.64.1 to 181.14.127.254181.14.127.25516,382
59181.14.128.0/18181.14.128.1 to 181.14.191.254181.14.191.25516,382
60181.14.192.0/18181.14.192.1 to 181.14.255.254181.14.255.25516,382
61181.15.0.0/18181.15.0.1 to 181.15.63.254181.15.63.25516,382
62181.15.64.0/18181.15.64.1 to 181.15.127.254181.15.127.25516,382
63181.15.128.0/18181.15.128.1 to 181.15.191.254181.15.191.25516,382
64181.15.192.0/18181.15.192.1 to 181.15.255.254181.15.255.25516,382
65181.16.0.0/18181.16.0.1 to 181.16.63.254181.16.63.25516,382
66181.16.64.0/18181.16.64.1 to 181.16.127.254181.16.127.25516,382
67181.16.128.0/18181.16.128.1 to 181.16.191.254181.16.191.25516,382
68181.16.192.0/18181.16.192.1 to 181.16.255.254181.16.255.25516,382
69181.17.0.0/18181.17.0.1 to 181.17.63.254181.17.63.25516,382
70181.17.64.0/18181.17.64.1 to 181.17.127.254181.17.127.25516,382
71181.17.128.0/18181.17.128.1 to 181.17.191.254181.17.191.25516,382
72181.17.192.0/18181.17.192.1 to 181.17.255.254181.17.255.25516,382
73181.18.0.0/18181.18.0.1 to 181.18.63.254181.18.63.25516,382
74181.18.64.0/18181.18.64.1 to 181.18.127.254181.18.127.25516,382
75181.18.128.0/18181.18.128.1 to 181.18.191.254181.18.191.25516,382
76181.18.192.0/18181.18.192.1 to 181.18.255.254181.18.255.25516,382
77181.19.0.0/18181.19.0.1 to 181.19.63.254181.19.63.25516,382
78181.19.64.0/18181.19.64.1 to 181.19.127.254181.19.127.25516,382
79181.19.128.0/18181.19.128.1 to 181.19.191.254181.19.191.25516,382
80181.19.192.0/18181.19.192.1 to 181.19.255.254181.19.255.25516,382
81181.20.0.0/18181.20.0.1 to 181.20.63.254181.20.63.25516,382
82181.20.64.0/18181.20.64.1 to 181.20.127.254181.20.127.25516,382
83181.20.128.0/18181.20.128.1 to 181.20.191.254181.20.191.25516,382
84181.20.192.0/18181.20.192.1 to 181.20.255.254181.20.255.25516,382
85181.21.0.0/18181.21.0.1 to 181.21.63.254181.21.63.25516,382
86181.21.64.0/18181.21.64.1 to 181.21.127.254181.21.127.25516,382
87181.21.128.0/18181.21.128.1 to 181.21.191.254181.21.191.25516,382
88181.21.192.0/18181.21.192.1 to 181.21.255.254181.21.255.25516,382
89181.22.0.0/18181.22.0.1 to 181.22.63.254181.22.63.25516,382
90181.22.64.0/18181.22.64.1 to 181.22.127.254181.22.127.25516,382
91181.22.128.0/18181.22.128.1 to 181.22.191.254181.22.191.25516,382
92181.22.192.0/18181.22.192.1 to 181.22.255.254181.22.255.25516,382
93181.23.0.0/18181.23.0.1 to 181.23.63.254181.23.63.25516,382
94181.23.64.0/18181.23.64.1 to 181.23.127.254181.23.127.25516,382
95181.23.128.0/18181.23.128.1 to 181.23.191.254181.23.191.25516,382
96181.23.192.0/18181.23.192.1 to 181.23.255.254181.23.255.25516,382
97181.24.0.0/18181.24.0.1 to 181.24.63.254181.24.63.25516,382
98181.24.64.0/18181.24.64.1 to 181.24.127.254181.24.127.25516,382
99181.24.128.0/18181.24.128.1 to 181.24.191.254181.24.191.25516,382
100181.24.192.0/18181.24.192.1 to 181.24.255.254181.24.255.25516,382
101181.25.0.0/18181.25.0.1 to 181.25.63.254181.25.63.25516,382
102181.25.64.0/18181.25.64.1 to 181.25.127.254181.25.127.25516,382
103181.25.128.0/18181.25.128.1 to 181.25.191.254181.25.191.25516,382
104181.25.192.0/18181.25.192.1 to 181.25.255.254181.25.255.25516,382
105181.26.0.0/18181.26.0.1 to 181.26.63.254181.26.63.25516,382
106181.26.64.0/18181.26.64.1 to 181.26.127.254181.26.127.25516,382
107181.26.128.0/18181.26.128.1 to 181.26.191.254181.26.191.25516,382
108181.26.192.0/18181.26.192.1 to 181.26.255.254181.26.255.25516,382
109181.27.0.0/18181.27.0.1 to 181.27.63.254181.27.63.25516,382
110181.27.64.0/18181.27.64.1 to 181.27.127.254181.27.127.25516,382
111181.27.128.0/18181.27.128.1 to 181.27.191.254181.27.191.25516,382
112181.27.192.0/18181.27.192.1 to 181.27.255.254181.27.255.25516,382
113181.28.0.0/18181.28.0.1 to 181.28.63.254181.28.63.25516,382
114181.28.64.0/18181.28.64.1 to 181.28.127.254181.28.127.25516,382
115181.28.128.0/18181.28.128.1 to 181.28.191.254181.28.191.25516,382
116181.28.192.0/18181.28.192.1 to 181.28.255.254181.28.255.25516,382
117181.29.0.0/18181.29.0.1 to 181.29.63.254181.29.63.25516,382
118181.29.64.0/18181.29.64.1 to 181.29.127.254181.29.127.25516,382
119181.29.128.0/18181.29.128.1 to 181.29.191.254181.29.191.25516,382
120181.29.192.0/18181.29.192.1 to 181.29.255.254181.29.255.25516,382
121181.30.0.0/18181.30.0.1 to 181.30.63.254181.30.63.25516,382
122181.30.64.0/18181.30.64.1 to 181.30.127.254181.30.127.25516,382
123181.30.128.0/18181.30.128.1 to 181.30.191.254181.30.191.25516,382
124181.30.192.0/18181.30.192.1 to 181.30.255.254181.30.255.25516,382
125181.31.0.0/18181.31.0.1 to 181.31.63.254181.31.63.25516,382
126181.31.64.0/18181.31.64.1 to 181.31.127.254181.31.127.25516,382
127181.31.128.0/18181.31.128.1 to 181.31.191.254181.31.191.25516,382
128181.31.192.0/18181.31.192.1 to 181.31.255.254181.31.255.25516,382
129181.32.0.0/18181.32.0.1 to 181.32.63.254181.32.63.25516,382
130181.32.64.0/18181.32.64.1 to 181.32.127.254181.32.127.25516,382
131181.32.128.0/18181.32.128.1 to 181.32.191.254181.32.191.25516,382
132181.32.192.0/18181.32.192.1 to 181.32.255.254181.32.255.25516,382
133181.33.0.0/18181.33.0.1 to 181.33.63.254181.33.63.25516,382
134181.33.64.0/18181.33.64.1 to 181.33.127.254181.33.127.25516,382
135181.33.128.0/18181.33.128.1 to 181.33.191.254181.33.191.25516,382
136181.33.192.0/18181.33.192.1 to 181.33.255.254181.33.255.25516,382
137181.34.0.0/18181.34.0.1 to 181.34.63.254181.34.63.25516,382
138181.34.64.0/18181.34.64.1 to 181.34.127.254181.34.127.25516,382
139181.34.128.0/18181.34.128.1 to 181.34.191.254181.34.191.25516,382
140181.34.192.0/18181.34.192.1 to 181.34.255.254181.34.255.25516,382
141181.35.0.0/18181.35.0.1 to 181.35.63.254181.35.63.25516,382
142181.35.64.0/18181.35.64.1 to 181.35.127.254181.35.127.25516,382
143181.35.128.0/18181.35.128.1 to 181.35.191.254181.35.191.25516,382
144181.35.192.0/18181.35.192.1 to 181.35.255.254181.35.255.25516,382
145181.36.0.0/18181.36.0.1 to 181.36.63.254181.36.63.25516,382
146181.36.64.0/18181.36.64.1 to 181.36.127.254181.36.127.25516,382
147181.36.128.0/18181.36.128.1 to 181.36.191.254181.36.191.25516,382
148181.36.192.0/18181.36.192.1 to 181.36.255.254181.36.255.25516,382
149181.37.0.0/18181.37.0.1 to 181.37.63.254181.37.63.25516,382
150181.37.64.0/18181.37.64.1 to 181.37.127.254181.37.127.25516,382
151181.37.128.0/18181.37.128.1 to 181.37.191.254181.37.191.25516,382
152181.37.192.0/18181.37.192.1 to 181.37.255.254181.37.255.25516,382
153181.38.0.0/18181.38.0.1 to 181.38.63.254181.38.63.25516,382
154181.38.64.0/18181.38.64.1 to 181.38.127.254181.38.127.25516,382
155181.38.128.0/18181.38.128.1 to 181.38.191.254181.38.191.25516,382
156181.38.192.0/18181.38.192.1 to 181.38.255.254181.38.255.25516,382
157181.39.0.0/18181.39.0.1 to 181.39.63.254181.39.63.25516,382
158181.39.64.0/18181.39.64.1 to 181.39.127.254181.39.127.25516,382
159181.39.128.0/18181.39.128.1 to 181.39.191.254181.39.191.25516,382
160181.39.192.0/18181.39.192.1 to 181.39.255.254181.39.255.25516,382
161181.40.0.0/18181.40.0.1 to 181.40.63.254181.40.63.25516,382
162181.40.64.0/18181.40.64.1 to 181.40.127.254181.40.127.25516,382
163181.40.128.0/18181.40.128.1 to 181.40.191.254181.40.191.25516,382
164181.40.192.0/18181.40.192.1 to 181.40.255.254181.40.255.25516,382
165181.41.0.0/18181.41.0.1 to 181.41.63.254181.41.63.25516,382
166181.41.64.0/18181.41.64.1 to 181.41.127.254181.41.127.25516,382
167181.41.128.0/18181.41.128.1 to 181.41.191.254181.41.191.25516,382
168181.41.192.0/18181.41.192.1 to 181.41.255.254181.41.255.25516,382
169181.42.0.0/18181.42.0.1 to 181.42.63.254181.42.63.25516,382
170181.42.64.0/18181.42.64.1 to 181.42.127.254181.42.127.25516,382
171181.42.128.0/18181.42.128.1 to 181.42.191.254181.42.191.25516,382
172181.42.192.0/18181.42.192.1 to 181.42.255.254181.42.255.25516,382
173181.43.0.0/18181.43.0.1 to 181.43.63.254181.43.63.25516,382
174181.43.64.0/18181.43.64.1 to 181.43.127.254181.43.127.25516,382
175181.43.128.0/18181.43.128.1 to 181.43.191.254181.43.191.25516,382
176181.43.192.0/18181.43.192.1 to 181.43.255.254181.43.255.25516,382
177181.44.0.0/18181.44.0.1 to 181.44.63.254181.44.63.25516,382
178181.44.64.0/18181.44.64.1 to 181.44.127.254181.44.127.25516,382
179181.44.128.0/18181.44.128.1 to 181.44.191.254181.44.191.25516,382
180181.44.192.0/18181.44.192.1 to 181.44.255.254181.44.255.25516,382
181181.45.0.0/18181.45.0.1 to 181.45.63.254181.45.63.25516,382
182181.45.64.0/18181.45.64.1 to 181.45.127.254181.45.127.25516,382
183181.45.128.0/18181.45.128.1 to 181.45.191.254181.45.191.25516,382
184181.45.192.0/18181.45.192.1 to 181.45.255.254181.45.255.25516,382
185181.46.0.0/18181.46.0.1 to 181.46.63.254181.46.63.25516,382
186181.46.64.0/18181.46.64.1 to 181.46.127.254181.46.127.25516,382
187181.46.128.0/18181.46.128.1 to 181.46.191.254181.46.191.25516,382
188181.46.192.0/18181.46.192.1 to 181.46.255.254181.46.255.25516,382
189181.47.0.0/18181.47.0.1 to 181.47.63.254181.47.63.25516,382
190181.47.64.0/18181.47.64.1 to 181.47.127.254181.47.127.25516,382
191181.47.128.0/18181.47.128.1 to 181.47.191.254181.47.191.25516,382
192181.47.192.0/18181.47.192.1 to 181.47.255.254181.47.255.25516,382
193181.48.0.0/18181.48.0.1 to 181.48.63.254181.48.63.25516,382
194181.48.64.0/18181.48.64.1 to 181.48.127.254181.48.127.25516,382
195181.48.128.0/18181.48.128.1 to 181.48.191.254181.48.191.25516,382
196181.48.192.0/18181.48.192.1 to 181.48.255.254181.48.255.25516,382
197181.49.0.0/18181.49.0.1 to 181.49.63.254181.49.63.25516,382
198181.49.64.0/18181.49.64.1 to 181.49.127.254181.49.127.25516,382
199181.49.128.0/18181.49.128.1 to 181.49.191.254181.49.191.25516,382
200181.49.192.0/18181.49.192.1 to 181.49.255.254181.49.255.25516,382
201181.50.0.0/18181.50.0.1 to 181.50.63.254181.50.63.25516,382
202181.50.64.0/18181.50.64.1 to 181.50.127.254181.50.127.25516,382
203181.50.128.0/18181.50.128.1 to 181.50.191.254181.50.191.25516,382
204181.50.192.0/18181.50.192.1 to 181.50.255.254181.50.255.25516,382
205181.51.0.0/18181.51.0.1 to 181.51.63.254181.51.63.25516,382
206181.51.64.0/18181.51.64.1 to 181.51.127.254181.51.127.25516,382
207181.51.128.0/18181.51.128.1 to 181.51.191.254181.51.191.25516,382
208181.51.192.0/18181.51.192.1 to 181.51.255.254181.51.255.25516,382
209181.52.0.0/18181.52.0.1 to 181.52.63.254181.52.63.25516,382
210181.52.64.0/18181.52.64.1 to 181.52.127.254181.52.127.25516,382
211181.52.128.0/18181.52.128.1 to 181.52.191.254181.52.191.25516,382
212181.52.192.0/18181.52.192.1 to 181.52.255.254181.52.255.25516,382
213181.53.0.0/18181.53.0.1 to 181.53.63.254181.53.63.25516,382
214181.53.64.0/18181.53.64.1 to 181.53.127.254181.53.127.25516,382
215181.53.128.0/18181.53.128.1 to 181.53.191.254181.53.191.25516,382
216181.53.192.0/18181.53.192.1 to 181.53.255.254181.53.255.25516,382
217181.54.0.0/18181.54.0.1 to 181.54.63.254181.54.63.25516,382
218181.54.64.0/18181.54.64.1 to 181.54.127.254181.54.127.25516,382
219181.54.128.0/18181.54.128.1 to 181.54.191.254181.54.191.25516,382
220181.54.192.0/18181.54.192.1 to 181.54.255.254181.54.255.25516,382
221181.55.0.0/18181.55.0.1 to 181.55.63.254181.55.63.25516,382
222181.55.64.0/18181.55.64.1 to 181.55.127.254181.55.127.25516,382
223181.55.128.0/18181.55.128.1 to 181.55.191.254181.55.191.25516,382
224181.55.192.0/18181.55.192.1 to 181.55.255.254181.55.255.25516,382
225181.56.0.0/18181.56.0.1 to 181.56.63.254181.56.63.25516,382
226181.56.64.0/18181.56.64.1 to 181.56.127.254181.56.127.25516,382
227181.56.128.0/18181.56.128.1 to 181.56.191.254181.56.191.25516,382
228181.56.192.0/18181.56.192.1 to 181.56.255.254181.56.255.25516,382
229181.57.0.0/18181.57.0.1 to 181.57.63.254181.57.63.25516,382
230181.57.64.0/18181.57.64.1 to 181.57.127.254181.57.127.25516,382
231181.57.128.0/18181.57.128.1 to 181.57.191.254181.57.191.25516,382
232181.57.192.0/18181.57.192.1 to 181.57.255.254181.57.255.25516,382
233181.58.0.0/18181.58.0.1 to 181.58.63.254181.58.63.25516,382
234181.58.64.0/18181.58.64.1 to 181.58.127.254181.58.127.25516,382
235181.58.128.0/18181.58.128.1 to 181.58.191.254181.58.191.25516,382
236181.58.192.0/18181.58.192.1 to 181.58.255.254181.58.255.25516,382
237181.59.0.0/18181.59.0.1 to 181.59.63.254181.59.63.25516,382
238181.59.64.0/18181.59.64.1 to 181.59.127.254181.59.127.25516,382
239181.59.128.0/18181.59.128.1 to 181.59.191.254181.59.191.25516,382
240181.59.192.0/18181.59.192.1 to 181.59.255.254181.59.255.25516,382
241181.60.0.0/18181.60.0.1 to 181.60.63.254181.60.63.25516,382
242181.60.64.0/18181.60.64.1 to 181.60.127.254181.60.127.25516,382
243181.60.128.0/18181.60.128.1 to 181.60.191.254181.60.191.25516,382
244181.60.192.0/18181.60.192.1 to 181.60.255.254181.60.255.25516,382
245181.61.0.0/18181.61.0.1 to 181.61.63.254181.61.63.25516,382
246181.61.64.0/18181.61.64.1 to 181.61.127.254181.61.127.25516,382
247181.61.128.0/18181.61.128.1 to 181.61.191.254181.61.191.25516,382
248181.61.192.0/18181.61.192.1 to 181.61.255.254181.61.255.25516,382
249181.62.0.0/18181.62.0.1 to 181.62.63.254181.62.63.25516,382
250181.62.64.0/18181.62.64.1 to 181.62.127.254181.62.127.25516,382
251181.62.128.0/18181.62.128.1 to 181.62.191.254181.62.191.25516,382
252181.62.192.0/18181.62.192.1 to 181.62.255.254181.62.255.25516,382
253181.63.0.0/18181.63.0.1 to 181.63.63.254181.63.63.25516,382
254181.63.64.0/18181.63.64.1 to 181.63.127.254181.63.127.25516,382
255181.63.128.0/18181.63.128.1 to 181.63.191.254181.63.191.25516,382
256181.63.192.0/18181.63.192.1 to 181.63.255.254181.63.255.25516,382

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.