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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/19
/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 2,048 subnets of /19; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1161.0.0.0/19161.0.0.1 to 161.0.31.254161.0.31.2558,190
2161.0.32.0/19161.0.32.1 to 161.0.63.254161.0.63.2558,190
3161.0.64.0/19161.0.64.1 to 161.0.95.254161.0.95.2558,190
4161.0.96.0/19161.0.96.1 to 161.0.127.254161.0.127.2558,190
5161.0.128.0/19161.0.128.1 to 161.0.159.254161.0.159.2558,190
6161.0.160.0/19161.0.160.1 to 161.0.191.254161.0.191.2558,190
7161.0.192.0/19161.0.192.1 to 161.0.223.254161.0.223.2558,190
8161.0.224.0/19161.0.224.1 to 161.0.255.254161.0.255.2558,190
9161.1.0.0/19161.1.0.1 to 161.1.31.254161.1.31.2558,190
10161.1.32.0/19161.1.32.1 to 161.1.63.254161.1.63.2558,190
11161.1.64.0/19161.1.64.1 to 161.1.95.254161.1.95.2558,190
12161.1.96.0/19161.1.96.1 to 161.1.127.254161.1.127.2558,190
13161.1.128.0/19161.1.128.1 to 161.1.159.254161.1.159.2558,190
14161.1.160.0/19161.1.160.1 to 161.1.191.254161.1.191.2558,190
15161.1.192.0/19161.1.192.1 to 161.1.223.254161.1.223.2558,190
16161.1.224.0/19161.1.224.1 to 161.1.255.254161.1.255.2558,190
17161.2.0.0/19161.2.0.1 to 161.2.31.254161.2.31.2558,190
18161.2.32.0/19161.2.32.1 to 161.2.63.254161.2.63.2558,190
19161.2.64.0/19161.2.64.1 to 161.2.95.254161.2.95.2558,190
20161.2.96.0/19161.2.96.1 to 161.2.127.254161.2.127.2558,190
21161.2.128.0/19161.2.128.1 to 161.2.159.254161.2.159.2558,190
22161.2.160.0/19161.2.160.1 to 161.2.191.254161.2.191.2558,190
23161.2.192.0/19161.2.192.1 to 161.2.223.254161.2.223.2558,190
24161.2.224.0/19161.2.224.1 to 161.2.255.254161.2.255.2558,190
25161.3.0.0/19161.3.0.1 to 161.3.31.254161.3.31.2558,190
26161.3.32.0/19161.3.32.1 to 161.3.63.254161.3.63.2558,190
27161.3.64.0/19161.3.64.1 to 161.3.95.254161.3.95.2558,190
28161.3.96.0/19161.3.96.1 to 161.3.127.254161.3.127.2558,190
29161.3.128.0/19161.3.128.1 to 161.3.159.254161.3.159.2558,190
30161.3.160.0/19161.3.160.1 to 161.3.191.254161.3.191.2558,190
31161.3.192.0/19161.3.192.1 to 161.3.223.254161.3.223.2558,190
32161.3.224.0/19161.3.224.1 to 161.3.255.254161.3.255.2558,190
33161.4.0.0/19161.4.0.1 to 161.4.31.254161.4.31.2558,190
34161.4.32.0/19161.4.32.1 to 161.4.63.254161.4.63.2558,190
35161.4.64.0/19161.4.64.1 to 161.4.95.254161.4.95.2558,190
36161.4.96.0/19161.4.96.1 to 161.4.127.254161.4.127.2558,190
37161.4.128.0/19161.4.128.1 to 161.4.159.254161.4.159.2558,190
38161.4.160.0/19161.4.160.1 to 161.4.191.254161.4.191.2558,190
39161.4.192.0/19161.4.192.1 to 161.4.223.254161.4.223.2558,190
40161.4.224.0/19161.4.224.1 to 161.4.255.254161.4.255.2558,190
41161.5.0.0/19161.5.0.1 to 161.5.31.254161.5.31.2558,190
42161.5.32.0/19161.5.32.1 to 161.5.63.254161.5.63.2558,190
43161.5.64.0/19161.5.64.1 to 161.5.95.254161.5.95.2558,190
44161.5.96.0/19161.5.96.1 to 161.5.127.254161.5.127.2558,190
45161.5.128.0/19161.5.128.1 to 161.5.159.254161.5.159.2558,190
46161.5.160.0/19161.5.160.1 to 161.5.191.254161.5.191.2558,190
47161.5.192.0/19161.5.192.1 to 161.5.223.254161.5.223.2558,190
48161.5.224.0/19161.5.224.1 to 161.5.255.254161.5.255.2558,190
49161.6.0.0/19161.6.0.1 to 161.6.31.254161.6.31.2558,190
50161.6.32.0/19161.6.32.1 to 161.6.63.254161.6.63.2558,190
51161.6.64.0/19161.6.64.1 to 161.6.95.254161.6.95.2558,190
52161.6.96.0/19161.6.96.1 to 161.6.127.254161.6.127.2558,190
53161.6.128.0/19161.6.128.1 to 161.6.159.254161.6.159.2558,190
54161.6.160.0/19161.6.160.1 to 161.6.191.254161.6.191.2558,190
55161.6.192.0/19161.6.192.1 to 161.6.223.254161.6.223.2558,190
56161.6.224.0/19161.6.224.1 to 161.6.255.254161.6.255.2558,190
57161.7.0.0/19161.7.0.1 to 161.7.31.254161.7.31.2558,190
58161.7.32.0/19161.7.32.1 to 161.7.63.254161.7.63.2558,190
59161.7.64.0/19161.7.64.1 to 161.7.95.254161.7.95.2558,190
60161.7.96.0/19161.7.96.1 to 161.7.127.254161.7.127.2558,190
61161.7.128.0/19161.7.128.1 to 161.7.159.254161.7.159.2558,190
62161.7.160.0/19161.7.160.1 to 161.7.191.254161.7.191.2558,190
63161.7.192.0/19161.7.192.1 to 161.7.223.254161.7.223.2558,190
64161.7.224.0/19161.7.224.1 to 161.7.255.254161.7.255.2558,190
65161.8.0.0/19161.8.0.1 to 161.8.31.254161.8.31.2558,190
66161.8.32.0/19161.8.32.1 to 161.8.63.254161.8.63.2558,190
67161.8.64.0/19161.8.64.1 to 161.8.95.254161.8.95.2558,190
68161.8.96.0/19161.8.96.1 to 161.8.127.254161.8.127.2558,190
69161.8.128.0/19161.8.128.1 to 161.8.159.254161.8.159.2558,190
70161.8.160.0/19161.8.160.1 to 161.8.191.254161.8.191.2558,190
71161.8.192.0/19161.8.192.1 to 161.8.223.254161.8.223.2558,190
72161.8.224.0/19161.8.224.1 to 161.8.255.254161.8.255.2558,190
73161.9.0.0/19161.9.0.1 to 161.9.31.254161.9.31.2558,190
74161.9.32.0/19161.9.32.1 to 161.9.63.254161.9.63.2558,190
75161.9.64.0/19161.9.64.1 to 161.9.95.254161.9.95.2558,190
76161.9.96.0/19161.9.96.1 to 161.9.127.254161.9.127.2558,190
77161.9.128.0/19161.9.128.1 to 161.9.159.254161.9.159.2558,190
78161.9.160.0/19161.9.160.1 to 161.9.191.254161.9.191.2558,190
79161.9.192.0/19161.9.192.1 to 161.9.223.254161.9.223.2558,190
80161.9.224.0/19161.9.224.1 to 161.9.255.254161.9.255.2558,190
81161.10.0.0/19161.10.0.1 to 161.10.31.254161.10.31.2558,190
82161.10.32.0/19161.10.32.1 to 161.10.63.254161.10.63.2558,190
83161.10.64.0/19161.10.64.1 to 161.10.95.254161.10.95.2558,190
84161.10.96.0/19161.10.96.1 to 161.10.127.254161.10.127.2558,190
85161.10.128.0/19161.10.128.1 to 161.10.159.254161.10.159.2558,190
86161.10.160.0/19161.10.160.1 to 161.10.191.254161.10.191.2558,190
87161.10.192.0/19161.10.192.1 to 161.10.223.254161.10.223.2558,190
88161.10.224.0/19161.10.224.1 to 161.10.255.254161.10.255.2558,190
89161.11.0.0/19161.11.0.1 to 161.11.31.254161.11.31.2558,190
90161.11.32.0/19161.11.32.1 to 161.11.63.254161.11.63.2558,190
91161.11.64.0/19161.11.64.1 to 161.11.95.254161.11.95.2558,190
92161.11.96.0/19161.11.96.1 to 161.11.127.254161.11.127.2558,190
93161.11.128.0/19161.11.128.1 to 161.11.159.254161.11.159.2558,190
94161.11.160.0/19161.11.160.1 to 161.11.191.254161.11.191.2558,190
95161.11.192.0/19161.11.192.1 to 161.11.223.254161.11.223.2558,190
96161.11.224.0/19161.11.224.1 to 161.11.255.254161.11.255.2558,190
97161.12.0.0/19161.12.0.1 to 161.12.31.254161.12.31.2558,190
98161.12.32.0/19161.12.32.1 to 161.12.63.254161.12.63.2558,190
99161.12.64.0/19161.12.64.1 to 161.12.95.254161.12.95.2558,190
100161.12.96.0/19161.12.96.1 to 161.12.127.254161.12.127.2558,190
101161.12.128.0/19161.12.128.1 to 161.12.159.254161.12.159.2558,190
102161.12.160.0/19161.12.160.1 to 161.12.191.254161.12.191.2558,190
103161.12.192.0/19161.12.192.1 to 161.12.223.254161.12.223.2558,190
104161.12.224.0/19161.12.224.1 to 161.12.255.254161.12.255.2558,190
105161.13.0.0/19161.13.0.1 to 161.13.31.254161.13.31.2558,190
106161.13.32.0/19161.13.32.1 to 161.13.63.254161.13.63.2558,190
107161.13.64.0/19161.13.64.1 to 161.13.95.254161.13.95.2558,190
108161.13.96.0/19161.13.96.1 to 161.13.127.254161.13.127.2558,190
109161.13.128.0/19161.13.128.1 to 161.13.159.254161.13.159.2558,190
110161.13.160.0/19161.13.160.1 to 161.13.191.254161.13.191.2558,190
111161.13.192.0/19161.13.192.1 to 161.13.223.254161.13.223.2558,190
112161.13.224.0/19161.13.224.1 to 161.13.255.254161.13.255.2558,190
113161.14.0.0/19161.14.0.1 to 161.14.31.254161.14.31.2558,190
114161.14.32.0/19161.14.32.1 to 161.14.63.254161.14.63.2558,190
115161.14.64.0/19161.14.64.1 to 161.14.95.254161.14.95.2558,190
116161.14.96.0/19161.14.96.1 to 161.14.127.254161.14.127.2558,190
117161.14.128.0/19161.14.128.1 to 161.14.159.254161.14.159.2558,190
118161.14.160.0/19161.14.160.1 to 161.14.191.254161.14.191.2558,190
119161.14.192.0/19161.14.192.1 to 161.14.223.254161.14.223.2558,190
120161.14.224.0/19161.14.224.1 to 161.14.255.254161.14.255.2558,190
121161.15.0.0/19161.15.0.1 to 161.15.31.254161.15.31.2558,190
122161.15.32.0/19161.15.32.1 to 161.15.63.254161.15.63.2558,190
123161.15.64.0/19161.15.64.1 to 161.15.95.254161.15.95.2558,190
124161.15.96.0/19161.15.96.1 to 161.15.127.254161.15.127.2558,190
125161.15.128.0/19161.15.128.1 to 161.15.159.254161.15.159.2558,190
126161.15.160.0/19161.15.160.1 to 161.15.191.254161.15.191.2558,190
127161.15.192.0/19161.15.192.1 to 161.15.223.254161.15.223.2558,190
128161.15.224.0/19161.15.224.1 to 161.15.255.254161.15.255.2558,190
129161.16.0.0/19161.16.0.1 to 161.16.31.254161.16.31.2558,190
130161.16.32.0/19161.16.32.1 to 161.16.63.254161.16.63.2558,190
131161.16.64.0/19161.16.64.1 to 161.16.95.254161.16.95.2558,190
132161.16.96.0/19161.16.96.1 to 161.16.127.254161.16.127.2558,190
133161.16.128.0/19161.16.128.1 to 161.16.159.254161.16.159.2558,190
134161.16.160.0/19161.16.160.1 to 161.16.191.254161.16.191.2558,190
135161.16.192.0/19161.16.192.1 to 161.16.223.254161.16.223.2558,190
136161.16.224.0/19161.16.224.1 to 161.16.255.254161.16.255.2558,190
137161.17.0.0/19161.17.0.1 to 161.17.31.254161.17.31.2558,190
138161.17.32.0/19161.17.32.1 to 161.17.63.254161.17.63.2558,190
139161.17.64.0/19161.17.64.1 to 161.17.95.254161.17.95.2558,190
140161.17.96.0/19161.17.96.1 to 161.17.127.254161.17.127.2558,190
141161.17.128.0/19161.17.128.1 to 161.17.159.254161.17.159.2558,190
142161.17.160.0/19161.17.160.1 to 161.17.191.254161.17.191.2558,190
143161.17.192.0/19161.17.192.1 to 161.17.223.254161.17.223.2558,190
144161.17.224.0/19161.17.224.1 to 161.17.255.254161.17.255.2558,190
145161.18.0.0/19161.18.0.1 to 161.18.31.254161.18.31.2558,190
146161.18.32.0/19161.18.32.1 to 161.18.63.254161.18.63.2558,190
147161.18.64.0/19161.18.64.1 to 161.18.95.254161.18.95.2558,190
148161.18.96.0/19161.18.96.1 to 161.18.127.254161.18.127.2558,190
149161.18.128.0/19161.18.128.1 to 161.18.159.254161.18.159.2558,190
150161.18.160.0/19161.18.160.1 to 161.18.191.254161.18.191.2558,190
151161.18.192.0/19161.18.192.1 to 161.18.223.254161.18.223.2558,190
152161.18.224.0/19161.18.224.1 to 161.18.255.254161.18.255.2558,190
153161.19.0.0/19161.19.0.1 to 161.19.31.254161.19.31.2558,190
154161.19.32.0/19161.19.32.1 to 161.19.63.254161.19.63.2558,190
155161.19.64.0/19161.19.64.1 to 161.19.95.254161.19.95.2558,190
156161.19.96.0/19161.19.96.1 to 161.19.127.254161.19.127.2558,190
157161.19.128.0/19161.19.128.1 to 161.19.159.254161.19.159.2558,190
158161.19.160.0/19161.19.160.1 to 161.19.191.254161.19.191.2558,190
159161.19.192.0/19161.19.192.1 to 161.19.223.254161.19.223.2558,190
160161.19.224.0/19161.19.224.1 to 161.19.255.254161.19.255.2558,190
161161.20.0.0/19161.20.0.1 to 161.20.31.254161.20.31.2558,190
162161.20.32.0/19161.20.32.1 to 161.20.63.254161.20.63.2558,190
163161.20.64.0/19161.20.64.1 to 161.20.95.254161.20.95.2558,190
164161.20.96.0/19161.20.96.1 to 161.20.127.254161.20.127.2558,190
165161.20.128.0/19161.20.128.1 to 161.20.159.254161.20.159.2558,190
166161.20.160.0/19161.20.160.1 to 161.20.191.254161.20.191.2558,190
167161.20.192.0/19161.20.192.1 to 161.20.223.254161.20.223.2558,190
168161.20.224.0/19161.20.224.1 to 161.20.255.254161.20.255.2558,190
169161.21.0.0/19161.21.0.1 to 161.21.31.254161.21.31.2558,190
170161.21.32.0/19161.21.32.1 to 161.21.63.254161.21.63.2558,190
171161.21.64.0/19161.21.64.1 to 161.21.95.254161.21.95.2558,190
172161.21.96.0/19161.21.96.1 to 161.21.127.254161.21.127.2558,190
173161.21.128.0/19161.21.128.1 to 161.21.159.254161.21.159.2558,190
174161.21.160.0/19161.21.160.1 to 161.21.191.254161.21.191.2558,190
175161.21.192.0/19161.21.192.1 to 161.21.223.254161.21.223.2558,190
176161.21.224.0/19161.21.224.1 to 161.21.255.254161.21.255.2558,190
177161.22.0.0/19161.22.0.1 to 161.22.31.254161.22.31.2558,190
178161.22.32.0/19161.22.32.1 to 161.22.63.254161.22.63.2558,190
179161.22.64.0/19161.22.64.1 to 161.22.95.254161.22.95.2558,190
180161.22.96.0/19161.22.96.1 to 161.22.127.254161.22.127.2558,190
181161.22.128.0/19161.22.128.1 to 161.22.159.254161.22.159.2558,190
182161.22.160.0/19161.22.160.1 to 161.22.191.254161.22.191.2558,190
183161.22.192.0/19161.22.192.1 to 161.22.223.254161.22.223.2558,190
184161.22.224.0/19161.22.224.1 to 161.22.255.254161.22.255.2558,190
185161.23.0.0/19161.23.0.1 to 161.23.31.254161.23.31.2558,190
186161.23.32.0/19161.23.32.1 to 161.23.63.254161.23.63.2558,190
187161.23.64.0/19161.23.64.1 to 161.23.95.254161.23.95.2558,190
188161.23.96.0/19161.23.96.1 to 161.23.127.254161.23.127.2558,190
189161.23.128.0/19161.23.128.1 to 161.23.159.254161.23.159.2558,190
190161.23.160.0/19161.23.160.1 to 161.23.191.254161.23.191.2558,190
191161.23.192.0/19161.23.192.1 to 161.23.223.254161.23.223.2558,190
192161.23.224.0/19161.23.224.1 to 161.23.255.254161.23.255.2558,190
193161.24.0.0/19161.24.0.1 to 161.24.31.254161.24.31.2558,190
194161.24.32.0/19161.24.32.1 to 161.24.63.254161.24.63.2558,190
195161.24.64.0/19161.24.64.1 to 161.24.95.254161.24.95.2558,190
196161.24.96.0/19161.24.96.1 to 161.24.127.254161.24.127.2558,190
197161.24.128.0/19161.24.128.1 to 161.24.159.254161.24.159.2558,190
198161.24.160.0/19161.24.160.1 to 161.24.191.254161.24.191.2558,190
199161.24.192.0/19161.24.192.1 to 161.24.223.254161.24.223.2558,190
200161.24.224.0/19161.24.224.1 to 161.24.255.254161.24.255.2558,190
201161.25.0.0/19161.25.0.1 to 161.25.31.254161.25.31.2558,190
202161.25.32.0/19161.25.32.1 to 161.25.63.254161.25.63.2558,190
203161.25.64.0/19161.25.64.1 to 161.25.95.254161.25.95.2558,190
204161.25.96.0/19161.25.96.1 to 161.25.127.254161.25.127.2558,190
205161.25.128.0/19161.25.128.1 to 161.25.159.254161.25.159.2558,190
206161.25.160.0/19161.25.160.1 to 161.25.191.254161.25.191.2558,190
207161.25.192.0/19161.25.192.1 to 161.25.223.254161.25.223.2558,190
208161.25.224.0/19161.25.224.1 to 161.25.255.254161.25.255.2558,190
209161.26.0.0/19161.26.0.1 to 161.26.31.254161.26.31.2558,190
210161.26.32.0/19161.26.32.1 to 161.26.63.254161.26.63.2558,190
211161.26.64.0/19161.26.64.1 to 161.26.95.254161.26.95.2558,190
212161.26.96.0/19161.26.96.1 to 161.26.127.254161.26.127.2558,190
213161.26.128.0/19161.26.128.1 to 161.26.159.254161.26.159.2558,190
214161.26.160.0/19161.26.160.1 to 161.26.191.254161.26.191.2558,190
215161.26.192.0/19161.26.192.1 to 161.26.223.254161.26.223.2558,190
216161.26.224.0/19161.26.224.1 to 161.26.255.254161.26.255.2558,190
217161.27.0.0/19161.27.0.1 to 161.27.31.254161.27.31.2558,190
218161.27.32.0/19161.27.32.1 to 161.27.63.254161.27.63.2558,190
219161.27.64.0/19161.27.64.1 to 161.27.95.254161.27.95.2558,190
220161.27.96.0/19161.27.96.1 to 161.27.127.254161.27.127.2558,190
221161.27.128.0/19161.27.128.1 to 161.27.159.254161.27.159.2558,190
222161.27.160.0/19161.27.160.1 to 161.27.191.254161.27.191.2558,190
223161.27.192.0/19161.27.192.1 to 161.27.223.254161.27.223.2558,190
224161.27.224.0/19161.27.224.1 to 161.27.255.254161.27.255.2558,190
225161.28.0.0/19161.28.0.1 to 161.28.31.254161.28.31.2558,190
226161.28.32.0/19161.28.32.1 to 161.28.63.254161.28.63.2558,190
227161.28.64.0/19161.28.64.1 to 161.28.95.254161.28.95.2558,190
228161.28.96.0/19161.28.96.1 to 161.28.127.254161.28.127.2558,190
229161.28.128.0/19161.28.128.1 to 161.28.159.254161.28.159.2558,190
230161.28.160.0/19161.28.160.1 to 161.28.191.254161.28.191.2558,190
231161.28.192.0/19161.28.192.1 to 161.28.223.254161.28.223.2558,190
232161.28.224.0/19161.28.224.1 to 161.28.255.254161.28.255.2558,190
233161.29.0.0/19161.29.0.1 to 161.29.31.254161.29.31.2558,190
234161.29.32.0/19161.29.32.1 to 161.29.63.254161.29.63.2558,190
235161.29.64.0/19161.29.64.1 to 161.29.95.254161.29.95.2558,190
236161.29.96.0/19161.29.96.1 to 161.29.127.254161.29.127.2558,190
237161.29.128.0/19161.29.128.1 to 161.29.159.254161.29.159.2558,190
238161.29.160.0/19161.29.160.1 to 161.29.191.254161.29.191.2558,190
239161.29.192.0/19161.29.192.1 to 161.29.223.254161.29.223.2558,190
240161.29.224.0/19161.29.224.1 to 161.29.255.254161.29.255.2558,190
241161.30.0.0/19161.30.0.1 to 161.30.31.254161.30.31.2558,190
242161.30.32.0/19161.30.32.1 to 161.30.63.254161.30.63.2558,190
243161.30.64.0/19161.30.64.1 to 161.30.95.254161.30.95.2558,190
244161.30.96.0/19161.30.96.1 to 161.30.127.254161.30.127.2558,190
245161.30.128.0/19161.30.128.1 to 161.30.159.254161.30.159.2558,190
246161.30.160.0/19161.30.160.1 to 161.30.191.254161.30.191.2558,190
247161.30.192.0/19161.30.192.1 to 161.30.223.254161.30.223.2558,190
248161.30.224.0/19161.30.224.1 to 161.30.255.254161.30.255.2558,190
249161.31.0.0/19161.31.0.1 to 161.31.31.254161.31.31.2558,190
250161.31.32.0/19161.31.32.1 to 161.31.63.254161.31.63.2558,190
251161.31.64.0/19161.31.64.1 to 161.31.95.254161.31.95.2558,190
252161.31.96.0/19161.31.96.1 to 161.31.127.254161.31.127.2558,190
253161.31.128.0/19161.31.128.1 to 161.31.159.254161.31.159.2558,190
254161.31.160.0/19161.31.160.1 to 161.31.191.254161.31.191.2558,190
255161.31.192.0/19161.31.192.1 to 161.31.223.254161.31.223.2558,190
256161.31.224.0/19161.31.224.1 to 161.31.255.254161.31.255.2558,190

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.