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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.

Network161.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
161.0.0.0
Broadcast address
161.255.255.255
First usable
161.0.0.1
Last usable
161.255.255.254
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 A1000000 · Integer 2701131776 to 2717908991
Reverse DNS zone
161.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10100001..00000000.00000000.00000000161.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network10100001..00000000.00000000.00000000161.0.0.0
Broadcast10100001..11111111.11111111.11111111161.255.255.255
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)

161.0.0.0/8 makes 1,024 subnets of /18; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1161.0.0.0/18161.0.0.1 to 161.0.63.254161.0.63.25516,382
2161.0.64.0/18161.0.64.1 to 161.0.127.254161.0.127.25516,382
3161.0.128.0/18161.0.128.1 to 161.0.191.254161.0.191.25516,382
4161.0.192.0/18161.0.192.1 to 161.0.255.254161.0.255.25516,382
5161.1.0.0/18161.1.0.1 to 161.1.63.254161.1.63.25516,382
6161.1.64.0/18161.1.64.1 to 161.1.127.254161.1.127.25516,382
7161.1.128.0/18161.1.128.1 to 161.1.191.254161.1.191.25516,382
8161.1.192.0/18161.1.192.1 to 161.1.255.254161.1.255.25516,382
9161.2.0.0/18161.2.0.1 to 161.2.63.254161.2.63.25516,382
10161.2.64.0/18161.2.64.1 to 161.2.127.254161.2.127.25516,382
11161.2.128.0/18161.2.128.1 to 161.2.191.254161.2.191.25516,382
12161.2.192.0/18161.2.192.1 to 161.2.255.254161.2.255.25516,382
13161.3.0.0/18161.3.0.1 to 161.3.63.254161.3.63.25516,382
14161.3.64.0/18161.3.64.1 to 161.3.127.254161.3.127.25516,382
15161.3.128.0/18161.3.128.1 to 161.3.191.254161.3.191.25516,382
16161.3.192.0/18161.3.192.1 to 161.3.255.254161.3.255.25516,382
17161.4.0.0/18161.4.0.1 to 161.4.63.254161.4.63.25516,382
18161.4.64.0/18161.4.64.1 to 161.4.127.254161.4.127.25516,382
19161.4.128.0/18161.4.128.1 to 161.4.191.254161.4.191.25516,382
20161.4.192.0/18161.4.192.1 to 161.4.255.254161.4.255.25516,382
21161.5.0.0/18161.5.0.1 to 161.5.63.254161.5.63.25516,382
22161.5.64.0/18161.5.64.1 to 161.5.127.254161.5.127.25516,382
23161.5.128.0/18161.5.128.1 to 161.5.191.254161.5.191.25516,382
24161.5.192.0/18161.5.192.1 to 161.5.255.254161.5.255.25516,382
25161.6.0.0/18161.6.0.1 to 161.6.63.254161.6.63.25516,382
26161.6.64.0/18161.6.64.1 to 161.6.127.254161.6.127.25516,382
27161.6.128.0/18161.6.128.1 to 161.6.191.254161.6.191.25516,382
28161.6.192.0/18161.6.192.1 to 161.6.255.254161.6.255.25516,382
29161.7.0.0/18161.7.0.1 to 161.7.63.254161.7.63.25516,382
30161.7.64.0/18161.7.64.1 to 161.7.127.254161.7.127.25516,382
31161.7.128.0/18161.7.128.1 to 161.7.191.254161.7.191.25516,382
32161.7.192.0/18161.7.192.1 to 161.7.255.254161.7.255.25516,382
33161.8.0.0/18161.8.0.1 to 161.8.63.254161.8.63.25516,382
34161.8.64.0/18161.8.64.1 to 161.8.127.254161.8.127.25516,382
35161.8.128.0/18161.8.128.1 to 161.8.191.254161.8.191.25516,382
36161.8.192.0/18161.8.192.1 to 161.8.255.254161.8.255.25516,382
37161.9.0.0/18161.9.0.1 to 161.9.63.254161.9.63.25516,382
38161.9.64.0/18161.9.64.1 to 161.9.127.254161.9.127.25516,382
39161.9.128.0/18161.9.128.1 to 161.9.191.254161.9.191.25516,382
40161.9.192.0/18161.9.192.1 to 161.9.255.254161.9.255.25516,382
41161.10.0.0/18161.10.0.1 to 161.10.63.254161.10.63.25516,382
42161.10.64.0/18161.10.64.1 to 161.10.127.254161.10.127.25516,382
43161.10.128.0/18161.10.128.1 to 161.10.191.254161.10.191.25516,382
44161.10.192.0/18161.10.192.1 to 161.10.255.254161.10.255.25516,382
45161.11.0.0/18161.11.0.1 to 161.11.63.254161.11.63.25516,382
46161.11.64.0/18161.11.64.1 to 161.11.127.254161.11.127.25516,382
47161.11.128.0/18161.11.128.1 to 161.11.191.254161.11.191.25516,382
48161.11.192.0/18161.11.192.1 to 161.11.255.254161.11.255.25516,382
49161.12.0.0/18161.12.0.1 to 161.12.63.254161.12.63.25516,382
50161.12.64.0/18161.12.64.1 to 161.12.127.254161.12.127.25516,382
51161.12.128.0/18161.12.128.1 to 161.12.191.254161.12.191.25516,382
52161.12.192.0/18161.12.192.1 to 161.12.255.254161.12.255.25516,382
53161.13.0.0/18161.13.0.1 to 161.13.63.254161.13.63.25516,382
54161.13.64.0/18161.13.64.1 to 161.13.127.254161.13.127.25516,382
55161.13.128.0/18161.13.128.1 to 161.13.191.254161.13.191.25516,382
56161.13.192.0/18161.13.192.1 to 161.13.255.254161.13.255.25516,382
57161.14.0.0/18161.14.0.1 to 161.14.63.254161.14.63.25516,382
58161.14.64.0/18161.14.64.1 to 161.14.127.254161.14.127.25516,382
59161.14.128.0/18161.14.128.1 to 161.14.191.254161.14.191.25516,382
60161.14.192.0/18161.14.192.1 to 161.14.255.254161.14.255.25516,382
61161.15.0.0/18161.15.0.1 to 161.15.63.254161.15.63.25516,382
62161.15.64.0/18161.15.64.1 to 161.15.127.254161.15.127.25516,382
63161.15.128.0/18161.15.128.1 to 161.15.191.254161.15.191.25516,382
64161.15.192.0/18161.15.192.1 to 161.15.255.254161.15.255.25516,382
65161.16.0.0/18161.16.0.1 to 161.16.63.254161.16.63.25516,382
66161.16.64.0/18161.16.64.1 to 161.16.127.254161.16.127.25516,382
67161.16.128.0/18161.16.128.1 to 161.16.191.254161.16.191.25516,382
68161.16.192.0/18161.16.192.1 to 161.16.255.254161.16.255.25516,382
69161.17.0.0/18161.17.0.1 to 161.17.63.254161.17.63.25516,382
70161.17.64.0/18161.17.64.1 to 161.17.127.254161.17.127.25516,382
71161.17.128.0/18161.17.128.1 to 161.17.191.254161.17.191.25516,382
72161.17.192.0/18161.17.192.1 to 161.17.255.254161.17.255.25516,382
73161.18.0.0/18161.18.0.1 to 161.18.63.254161.18.63.25516,382
74161.18.64.0/18161.18.64.1 to 161.18.127.254161.18.127.25516,382
75161.18.128.0/18161.18.128.1 to 161.18.191.254161.18.191.25516,382
76161.18.192.0/18161.18.192.1 to 161.18.255.254161.18.255.25516,382
77161.19.0.0/18161.19.0.1 to 161.19.63.254161.19.63.25516,382
78161.19.64.0/18161.19.64.1 to 161.19.127.254161.19.127.25516,382
79161.19.128.0/18161.19.128.1 to 161.19.191.254161.19.191.25516,382
80161.19.192.0/18161.19.192.1 to 161.19.255.254161.19.255.25516,382
81161.20.0.0/18161.20.0.1 to 161.20.63.254161.20.63.25516,382
82161.20.64.0/18161.20.64.1 to 161.20.127.254161.20.127.25516,382
83161.20.128.0/18161.20.128.1 to 161.20.191.254161.20.191.25516,382
84161.20.192.0/18161.20.192.1 to 161.20.255.254161.20.255.25516,382
85161.21.0.0/18161.21.0.1 to 161.21.63.254161.21.63.25516,382
86161.21.64.0/18161.21.64.1 to 161.21.127.254161.21.127.25516,382
87161.21.128.0/18161.21.128.1 to 161.21.191.254161.21.191.25516,382
88161.21.192.0/18161.21.192.1 to 161.21.255.254161.21.255.25516,382
89161.22.0.0/18161.22.0.1 to 161.22.63.254161.22.63.25516,382
90161.22.64.0/18161.22.64.1 to 161.22.127.254161.22.127.25516,382
91161.22.128.0/18161.22.128.1 to 161.22.191.254161.22.191.25516,382
92161.22.192.0/18161.22.192.1 to 161.22.255.254161.22.255.25516,382
93161.23.0.0/18161.23.0.1 to 161.23.63.254161.23.63.25516,382
94161.23.64.0/18161.23.64.1 to 161.23.127.254161.23.127.25516,382
95161.23.128.0/18161.23.128.1 to 161.23.191.254161.23.191.25516,382
96161.23.192.0/18161.23.192.1 to 161.23.255.254161.23.255.25516,382
97161.24.0.0/18161.24.0.1 to 161.24.63.254161.24.63.25516,382
98161.24.64.0/18161.24.64.1 to 161.24.127.254161.24.127.25516,382
99161.24.128.0/18161.24.128.1 to 161.24.191.254161.24.191.25516,382
100161.24.192.0/18161.24.192.1 to 161.24.255.254161.24.255.25516,382
101161.25.0.0/18161.25.0.1 to 161.25.63.254161.25.63.25516,382
102161.25.64.0/18161.25.64.1 to 161.25.127.254161.25.127.25516,382
103161.25.128.0/18161.25.128.1 to 161.25.191.254161.25.191.25516,382
104161.25.192.0/18161.25.192.1 to 161.25.255.254161.25.255.25516,382
105161.26.0.0/18161.26.0.1 to 161.26.63.254161.26.63.25516,382
106161.26.64.0/18161.26.64.1 to 161.26.127.254161.26.127.25516,382
107161.26.128.0/18161.26.128.1 to 161.26.191.254161.26.191.25516,382
108161.26.192.0/18161.26.192.1 to 161.26.255.254161.26.255.25516,382
109161.27.0.0/18161.27.0.1 to 161.27.63.254161.27.63.25516,382
110161.27.64.0/18161.27.64.1 to 161.27.127.254161.27.127.25516,382
111161.27.128.0/18161.27.128.1 to 161.27.191.254161.27.191.25516,382
112161.27.192.0/18161.27.192.1 to 161.27.255.254161.27.255.25516,382
113161.28.0.0/18161.28.0.1 to 161.28.63.254161.28.63.25516,382
114161.28.64.0/18161.28.64.1 to 161.28.127.254161.28.127.25516,382
115161.28.128.0/18161.28.128.1 to 161.28.191.254161.28.191.25516,382
116161.28.192.0/18161.28.192.1 to 161.28.255.254161.28.255.25516,382
117161.29.0.0/18161.29.0.1 to 161.29.63.254161.29.63.25516,382
118161.29.64.0/18161.29.64.1 to 161.29.127.254161.29.127.25516,382
119161.29.128.0/18161.29.128.1 to 161.29.191.254161.29.191.25516,382
120161.29.192.0/18161.29.192.1 to 161.29.255.254161.29.255.25516,382
121161.30.0.0/18161.30.0.1 to 161.30.63.254161.30.63.25516,382
122161.30.64.0/18161.30.64.1 to 161.30.127.254161.30.127.25516,382
123161.30.128.0/18161.30.128.1 to 161.30.191.254161.30.191.25516,382
124161.30.192.0/18161.30.192.1 to 161.30.255.254161.30.255.25516,382
125161.31.0.0/18161.31.0.1 to 161.31.63.254161.31.63.25516,382
126161.31.64.0/18161.31.64.1 to 161.31.127.254161.31.127.25516,382
127161.31.128.0/18161.31.128.1 to 161.31.191.254161.31.191.25516,382
128161.31.192.0/18161.31.192.1 to 161.31.255.254161.31.255.25516,382
129161.32.0.0/18161.32.0.1 to 161.32.63.254161.32.63.25516,382
130161.32.64.0/18161.32.64.1 to 161.32.127.254161.32.127.25516,382
131161.32.128.0/18161.32.128.1 to 161.32.191.254161.32.191.25516,382
132161.32.192.0/18161.32.192.1 to 161.32.255.254161.32.255.25516,382
133161.33.0.0/18161.33.0.1 to 161.33.63.254161.33.63.25516,382
134161.33.64.0/18161.33.64.1 to 161.33.127.254161.33.127.25516,382
135161.33.128.0/18161.33.128.1 to 161.33.191.254161.33.191.25516,382
136161.33.192.0/18161.33.192.1 to 161.33.255.254161.33.255.25516,382
137161.34.0.0/18161.34.0.1 to 161.34.63.254161.34.63.25516,382
138161.34.64.0/18161.34.64.1 to 161.34.127.254161.34.127.25516,382
139161.34.128.0/18161.34.128.1 to 161.34.191.254161.34.191.25516,382
140161.34.192.0/18161.34.192.1 to 161.34.255.254161.34.255.25516,382
141161.35.0.0/18161.35.0.1 to 161.35.63.254161.35.63.25516,382
142161.35.64.0/18161.35.64.1 to 161.35.127.254161.35.127.25516,382
143161.35.128.0/18161.35.128.1 to 161.35.191.254161.35.191.25516,382
144161.35.192.0/18161.35.192.1 to 161.35.255.254161.35.255.25516,382
145161.36.0.0/18161.36.0.1 to 161.36.63.254161.36.63.25516,382
146161.36.64.0/18161.36.64.1 to 161.36.127.254161.36.127.25516,382
147161.36.128.0/18161.36.128.1 to 161.36.191.254161.36.191.25516,382
148161.36.192.0/18161.36.192.1 to 161.36.255.254161.36.255.25516,382
149161.37.0.0/18161.37.0.1 to 161.37.63.254161.37.63.25516,382
150161.37.64.0/18161.37.64.1 to 161.37.127.254161.37.127.25516,382
151161.37.128.0/18161.37.128.1 to 161.37.191.254161.37.191.25516,382
152161.37.192.0/18161.37.192.1 to 161.37.255.254161.37.255.25516,382
153161.38.0.0/18161.38.0.1 to 161.38.63.254161.38.63.25516,382
154161.38.64.0/18161.38.64.1 to 161.38.127.254161.38.127.25516,382
155161.38.128.0/18161.38.128.1 to 161.38.191.254161.38.191.25516,382
156161.38.192.0/18161.38.192.1 to 161.38.255.254161.38.255.25516,382
157161.39.0.0/18161.39.0.1 to 161.39.63.254161.39.63.25516,382
158161.39.64.0/18161.39.64.1 to 161.39.127.254161.39.127.25516,382
159161.39.128.0/18161.39.128.1 to 161.39.191.254161.39.191.25516,382
160161.39.192.0/18161.39.192.1 to 161.39.255.254161.39.255.25516,382
161161.40.0.0/18161.40.0.1 to 161.40.63.254161.40.63.25516,382
162161.40.64.0/18161.40.64.1 to 161.40.127.254161.40.127.25516,382
163161.40.128.0/18161.40.128.1 to 161.40.191.254161.40.191.25516,382
164161.40.192.0/18161.40.192.1 to 161.40.255.254161.40.255.25516,382
165161.41.0.0/18161.41.0.1 to 161.41.63.254161.41.63.25516,382
166161.41.64.0/18161.41.64.1 to 161.41.127.254161.41.127.25516,382
167161.41.128.0/18161.41.128.1 to 161.41.191.254161.41.191.25516,382
168161.41.192.0/18161.41.192.1 to 161.41.255.254161.41.255.25516,382
169161.42.0.0/18161.42.0.1 to 161.42.63.254161.42.63.25516,382
170161.42.64.0/18161.42.64.1 to 161.42.127.254161.42.127.25516,382
171161.42.128.0/18161.42.128.1 to 161.42.191.254161.42.191.25516,382
172161.42.192.0/18161.42.192.1 to 161.42.255.254161.42.255.25516,382
173161.43.0.0/18161.43.0.1 to 161.43.63.254161.43.63.25516,382
174161.43.64.0/18161.43.64.1 to 161.43.127.254161.43.127.25516,382
175161.43.128.0/18161.43.128.1 to 161.43.191.254161.43.191.25516,382
176161.43.192.0/18161.43.192.1 to 161.43.255.254161.43.255.25516,382
177161.44.0.0/18161.44.0.1 to 161.44.63.254161.44.63.25516,382
178161.44.64.0/18161.44.64.1 to 161.44.127.254161.44.127.25516,382
179161.44.128.0/18161.44.128.1 to 161.44.191.254161.44.191.25516,382
180161.44.192.0/18161.44.192.1 to 161.44.255.254161.44.255.25516,382
181161.45.0.0/18161.45.0.1 to 161.45.63.254161.45.63.25516,382
182161.45.64.0/18161.45.64.1 to 161.45.127.254161.45.127.25516,382
183161.45.128.0/18161.45.128.1 to 161.45.191.254161.45.191.25516,382
184161.45.192.0/18161.45.192.1 to 161.45.255.254161.45.255.25516,382
185161.46.0.0/18161.46.0.1 to 161.46.63.254161.46.63.25516,382
186161.46.64.0/18161.46.64.1 to 161.46.127.254161.46.127.25516,382
187161.46.128.0/18161.46.128.1 to 161.46.191.254161.46.191.25516,382
188161.46.192.0/18161.46.192.1 to 161.46.255.254161.46.255.25516,382
189161.47.0.0/18161.47.0.1 to 161.47.63.254161.47.63.25516,382
190161.47.64.0/18161.47.64.1 to 161.47.127.254161.47.127.25516,382
191161.47.128.0/18161.47.128.1 to 161.47.191.254161.47.191.25516,382
192161.47.192.0/18161.47.192.1 to 161.47.255.254161.47.255.25516,382
193161.48.0.0/18161.48.0.1 to 161.48.63.254161.48.63.25516,382
194161.48.64.0/18161.48.64.1 to 161.48.127.254161.48.127.25516,382
195161.48.128.0/18161.48.128.1 to 161.48.191.254161.48.191.25516,382
196161.48.192.0/18161.48.192.1 to 161.48.255.254161.48.255.25516,382
197161.49.0.0/18161.49.0.1 to 161.49.63.254161.49.63.25516,382
198161.49.64.0/18161.49.64.1 to 161.49.127.254161.49.127.25516,382
199161.49.128.0/18161.49.128.1 to 161.49.191.254161.49.191.25516,382
200161.49.192.0/18161.49.192.1 to 161.49.255.254161.49.255.25516,382
201161.50.0.0/18161.50.0.1 to 161.50.63.254161.50.63.25516,382
202161.50.64.0/18161.50.64.1 to 161.50.127.254161.50.127.25516,382
203161.50.128.0/18161.50.128.1 to 161.50.191.254161.50.191.25516,382
204161.50.192.0/18161.50.192.1 to 161.50.255.254161.50.255.25516,382
205161.51.0.0/18161.51.0.1 to 161.51.63.254161.51.63.25516,382
206161.51.64.0/18161.51.64.1 to 161.51.127.254161.51.127.25516,382
207161.51.128.0/18161.51.128.1 to 161.51.191.254161.51.191.25516,382
208161.51.192.0/18161.51.192.1 to 161.51.255.254161.51.255.25516,382
209161.52.0.0/18161.52.0.1 to 161.52.63.254161.52.63.25516,382
210161.52.64.0/18161.52.64.1 to 161.52.127.254161.52.127.25516,382
211161.52.128.0/18161.52.128.1 to 161.52.191.254161.52.191.25516,382
212161.52.192.0/18161.52.192.1 to 161.52.255.254161.52.255.25516,382
213161.53.0.0/18161.53.0.1 to 161.53.63.254161.53.63.25516,382
214161.53.64.0/18161.53.64.1 to 161.53.127.254161.53.127.25516,382
215161.53.128.0/18161.53.128.1 to 161.53.191.254161.53.191.25516,382
216161.53.192.0/18161.53.192.1 to 161.53.255.254161.53.255.25516,382
217161.54.0.0/18161.54.0.1 to 161.54.63.254161.54.63.25516,382
218161.54.64.0/18161.54.64.1 to 161.54.127.254161.54.127.25516,382
219161.54.128.0/18161.54.128.1 to 161.54.191.254161.54.191.25516,382
220161.54.192.0/18161.54.192.1 to 161.54.255.254161.54.255.25516,382
221161.55.0.0/18161.55.0.1 to 161.55.63.254161.55.63.25516,382
222161.55.64.0/18161.55.64.1 to 161.55.127.254161.55.127.25516,382
223161.55.128.0/18161.55.128.1 to 161.55.191.254161.55.191.25516,382
224161.55.192.0/18161.55.192.1 to 161.55.255.254161.55.255.25516,382
225161.56.0.0/18161.56.0.1 to 161.56.63.254161.56.63.25516,382
226161.56.64.0/18161.56.64.1 to 161.56.127.254161.56.127.25516,382
227161.56.128.0/18161.56.128.1 to 161.56.191.254161.56.191.25516,382
228161.56.192.0/18161.56.192.1 to 161.56.255.254161.56.255.25516,382
229161.57.0.0/18161.57.0.1 to 161.57.63.254161.57.63.25516,382
230161.57.64.0/18161.57.64.1 to 161.57.127.254161.57.127.25516,382
231161.57.128.0/18161.57.128.1 to 161.57.191.254161.57.191.25516,382
232161.57.192.0/18161.57.192.1 to 161.57.255.254161.57.255.25516,382
233161.58.0.0/18161.58.0.1 to 161.58.63.254161.58.63.25516,382
234161.58.64.0/18161.58.64.1 to 161.58.127.254161.58.127.25516,382
235161.58.128.0/18161.58.128.1 to 161.58.191.254161.58.191.25516,382
236161.58.192.0/18161.58.192.1 to 161.58.255.254161.58.255.25516,382
237161.59.0.0/18161.59.0.1 to 161.59.63.254161.59.63.25516,382
238161.59.64.0/18161.59.64.1 to 161.59.127.254161.59.127.25516,382
239161.59.128.0/18161.59.128.1 to 161.59.191.254161.59.191.25516,382
240161.59.192.0/18161.59.192.1 to 161.59.255.254161.59.255.25516,382
241161.60.0.0/18161.60.0.1 to 161.60.63.254161.60.63.25516,382
242161.60.64.0/18161.60.64.1 to 161.60.127.254161.60.127.25516,382
243161.60.128.0/18161.60.128.1 to 161.60.191.254161.60.191.25516,382
244161.60.192.0/18161.60.192.1 to 161.60.255.254161.60.255.25516,382
245161.61.0.0/18161.61.0.1 to 161.61.63.254161.61.63.25516,382
246161.61.64.0/18161.61.64.1 to 161.61.127.254161.61.127.25516,382
247161.61.128.0/18161.61.128.1 to 161.61.191.254161.61.191.25516,382
248161.61.192.0/18161.61.192.1 to 161.61.255.254161.61.255.25516,382
249161.62.0.0/18161.62.0.1 to 161.62.63.254161.62.63.25516,382
250161.62.64.0/18161.62.64.1 to 161.62.127.254161.62.127.25516,382
251161.62.128.0/18161.62.128.1 to 161.62.191.254161.62.191.25516,382
252161.62.192.0/18161.62.192.1 to 161.62.255.254161.62.255.25516,382
253161.63.0.0/18161.63.0.1 to 161.63.63.254161.63.63.25516,382
254161.63.64.0/18161.63.64.1 to 161.63.127.254161.63.127.25516,382
255161.63.128.0/18161.63.128.1 to 161.63.191.254161.63.191.25516,382
256161.63.192.0/18161.63.192.1 to 161.63.255.254161.63.255.25516,382

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.