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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/20
/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 4,096 subnets of /20; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1161.0.0.0/20161.0.0.1 to 161.0.15.254161.0.15.2554,094
2161.0.16.0/20161.0.16.1 to 161.0.31.254161.0.31.2554,094
3161.0.32.0/20161.0.32.1 to 161.0.47.254161.0.47.2554,094
4161.0.48.0/20161.0.48.1 to 161.0.63.254161.0.63.2554,094
5161.0.64.0/20161.0.64.1 to 161.0.79.254161.0.79.2554,094
6161.0.80.0/20161.0.80.1 to 161.0.95.254161.0.95.2554,094
7161.0.96.0/20161.0.96.1 to 161.0.111.254161.0.111.2554,094
8161.0.112.0/20161.0.112.1 to 161.0.127.254161.0.127.2554,094
9161.0.128.0/20161.0.128.1 to 161.0.143.254161.0.143.2554,094
10161.0.144.0/20161.0.144.1 to 161.0.159.254161.0.159.2554,094
11161.0.160.0/20161.0.160.1 to 161.0.175.254161.0.175.2554,094
12161.0.176.0/20161.0.176.1 to 161.0.191.254161.0.191.2554,094
13161.0.192.0/20161.0.192.1 to 161.0.207.254161.0.207.2554,094
14161.0.208.0/20161.0.208.1 to 161.0.223.254161.0.223.2554,094
15161.0.224.0/20161.0.224.1 to 161.0.239.254161.0.239.2554,094
16161.0.240.0/20161.0.240.1 to 161.0.255.254161.0.255.2554,094
17161.1.0.0/20161.1.0.1 to 161.1.15.254161.1.15.2554,094
18161.1.16.0/20161.1.16.1 to 161.1.31.254161.1.31.2554,094
19161.1.32.0/20161.1.32.1 to 161.1.47.254161.1.47.2554,094
20161.1.48.0/20161.1.48.1 to 161.1.63.254161.1.63.2554,094
21161.1.64.0/20161.1.64.1 to 161.1.79.254161.1.79.2554,094
22161.1.80.0/20161.1.80.1 to 161.1.95.254161.1.95.2554,094
23161.1.96.0/20161.1.96.1 to 161.1.111.254161.1.111.2554,094
24161.1.112.0/20161.1.112.1 to 161.1.127.254161.1.127.2554,094
25161.1.128.0/20161.1.128.1 to 161.1.143.254161.1.143.2554,094
26161.1.144.0/20161.1.144.1 to 161.1.159.254161.1.159.2554,094
27161.1.160.0/20161.1.160.1 to 161.1.175.254161.1.175.2554,094
28161.1.176.0/20161.1.176.1 to 161.1.191.254161.1.191.2554,094
29161.1.192.0/20161.1.192.1 to 161.1.207.254161.1.207.2554,094
30161.1.208.0/20161.1.208.1 to 161.1.223.254161.1.223.2554,094
31161.1.224.0/20161.1.224.1 to 161.1.239.254161.1.239.2554,094
32161.1.240.0/20161.1.240.1 to 161.1.255.254161.1.255.2554,094
33161.2.0.0/20161.2.0.1 to 161.2.15.254161.2.15.2554,094
34161.2.16.0/20161.2.16.1 to 161.2.31.254161.2.31.2554,094
35161.2.32.0/20161.2.32.1 to 161.2.47.254161.2.47.2554,094
36161.2.48.0/20161.2.48.1 to 161.2.63.254161.2.63.2554,094
37161.2.64.0/20161.2.64.1 to 161.2.79.254161.2.79.2554,094
38161.2.80.0/20161.2.80.1 to 161.2.95.254161.2.95.2554,094
39161.2.96.0/20161.2.96.1 to 161.2.111.254161.2.111.2554,094
40161.2.112.0/20161.2.112.1 to 161.2.127.254161.2.127.2554,094
41161.2.128.0/20161.2.128.1 to 161.2.143.254161.2.143.2554,094
42161.2.144.0/20161.2.144.1 to 161.2.159.254161.2.159.2554,094
43161.2.160.0/20161.2.160.1 to 161.2.175.254161.2.175.2554,094
44161.2.176.0/20161.2.176.1 to 161.2.191.254161.2.191.2554,094
45161.2.192.0/20161.2.192.1 to 161.2.207.254161.2.207.2554,094
46161.2.208.0/20161.2.208.1 to 161.2.223.254161.2.223.2554,094
47161.2.224.0/20161.2.224.1 to 161.2.239.254161.2.239.2554,094
48161.2.240.0/20161.2.240.1 to 161.2.255.254161.2.255.2554,094
49161.3.0.0/20161.3.0.1 to 161.3.15.254161.3.15.2554,094
50161.3.16.0/20161.3.16.1 to 161.3.31.254161.3.31.2554,094
51161.3.32.0/20161.3.32.1 to 161.3.47.254161.3.47.2554,094
52161.3.48.0/20161.3.48.1 to 161.3.63.254161.3.63.2554,094
53161.3.64.0/20161.3.64.1 to 161.3.79.254161.3.79.2554,094
54161.3.80.0/20161.3.80.1 to 161.3.95.254161.3.95.2554,094
55161.3.96.0/20161.3.96.1 to 161.3.111.254161.3.111.2554,094
56161.3.112.0/20161.3.112.1 to 161.3.127.254161.3.127.2554,094
57161.3.128.0/20161.3.128.1 to 161.3.143.254161.3.143.2554,094
58161.3.144.0/20161.3.144.1 to 161.3.159.254161.3.159.2554,094
59161.3.160.0/20161.3.160.1 to 161.3.175.254161.3.175.2554,094
60161.3.176.0/20161.3.176.1 to 161.3.191.254161.3.191.2554,094
61161.3.192.0/20161.3.192.1 to 161.3.207.254161.3.207.2554,094
62161.3.208.0/20161.3.208.1 to 161.3.223.254161.3.223.2554,094
63161.3.224.0/20161.3.224.1 to 161.3.239.254161.3.239.2554,094
64161.3.240.0/20161.3.240.1 to 161.3.255.254161.3.255.2554,094
65161.4.0.0/20161.4.0.1 to 161.4.15.254161.4.15.2554,094
66161.4.16.0/20161.4.16.1 to 161.4.31.254161.4.31.2554,094
67161.4.32.0/20161.4.32.1 to 161.4.47.254161.4.47.2554,094
68161.4.48.0/20161.4.48.1 to 161.4.63.254161.4.63.2554,094
69161.4.64.0/20161.4.64.1 to 161.4.79.254161.4.79.2554,094
70161.4.80.0/20161.4.80.1 to 161.4.95.254161.4.95.2554,094
71161.4.96.0/20161.4.96.1 to 161.4.111.254161.4.111.2554,094
72161.4.112.0/20161.4.112.1 to 161.4.127.254161.4.127.2554,094
73161.4.128.0/20161.4.128.1 to 161.4.143.254161.4.143.2554,094
74161.4.144.0/20161.4.144.1 to 161.4.159.254161.4.159.2554,094
75161.4.160.0/20161.4.160.1 to 161.4.175.254161.4.175.2554,094
76161.4.176.0/20161.4.176.1 to 161.4.191.254161.4.191.2554,094
77161.4.192.0/20161.4.192.1 to 161.4.207.254161.4.207.2554,094
78161.4.208.0/20161.4.208.1 to 161.4.223.254161.4.223.2554,094
79161.4.224.0/20161.4.224.1 to 161.4.239.254161.4.239.2554,094
80161.4.240.0/20161.4.240.1 to 161.4.255.254161.4.255.2554,094
81161.5.0.0/20161.5.0.1 to 161.5.15.254161.5.15.2554,094
82161.5.16.0/20161.5.16.1 to 161.5.31.254161.5.31.2554,094
83161.5.32.0/20161.5.32.1 to 161.5.47.254161.5.47.2554,094
84161.5.48.0/20161.5.48.1 to 161.5.63.254161.5.63.2554,094
85161.5.64.0/20161.5.64.1 to 161.5.79.254161.5.79.2554,094
86161.5.80.0/20161.5.80.1 to 161.5.95.254161.5.95.2554,094
87161.5.96.0/20161.5.96.1 to 161.5.111.254161.5.111.2554,094
88161.5.112.0/20161.5.112.1 to 161.5.127.254161.5.127.2554,094
89161.5.128.0/20161.5.128.1 to 161.5.143.254161.5.143.2554,094
90161.5.144.0/20161.5.144.1 to 161.5.159.254161.5.159.2554,094
91161.5.160.0/20161.5.160.1 to 161.5.175.254161.5.175.2554,094
92161.5.176.0/20161.5.176.1 to 161.5.191.254161.5.191.2554,094
93161.5.192.0/20161.5.192.1 to 161.5.207.254161.5.207.2554,094
94161.5.208.0/20161.5.208.1 to 161.5.223.254161.5.223.2554,094
95161.5.224.0/20161.5.224.1 to 161.5.239.254161.5.239.2554,094
96161.5.240.0/20161.5.240.1 to 161.5.255.254161.5.255.2554,094
97161.6.0.0/20161.6.0.1 to 161.6.15.254161.6.15.2554,094
98161.6.16.0/20161.6.16.1 to 161.6.31.254161.6.31.2554,094
99161.6.32.0/20161.6.32.1 to 161.6.47.254161.6.47.2554,094
100161.6.48.0/20161.6.48.1 to 161.6.63.254161.6.63.2554,094
101161.6.64.0/20161.6.64.1 to 161.6.79.254161.6.79.2554,094
102161.6.80.0/20161.6.80.1 to 161.6.95.254161.6.95.2554,094
103161.6.96.0/20161.6.96.1 to 161.6.111.254161.6.111.2554,094
104161.6.112.0/20161.6.112.1 to 161.6.127.254161.6.127.2554,094
105161.6.128.0/20161.6.128.1 to 161.6.143.254161.6.143.2554,094
106161.6.144.0/20161.6.144.1 to 161.6.159.254161.6.159.2554,094
107161.6.160.0/20161.6.160.1 to 161.6.175.254161.6.175.2554,094
108161.6.176.0/20161.6.176.1 to 161.6.191.254161.6.191.2554,094
109161.6.192.0/20161.6.192.1 to 161.6.207.254161.6.207.2554,094
110161.6.208.0/20161.6.208.1 to 161.6.223.254161.6.223.2554,094
111161.6.224.0/20161.6.224.1 to 161.6.239.254161.6.239.2554,094
112161.6.240.0/20161.6.240.1 to 161.6.255.254161.6.255.2554,094
113161.7.0.0/20161.7.0.1 to 161.7.15.254161.7.15.2554,094
114161.7.16.0/20161.7.16.1 to 161.7.31.254161.7.31.2554,094
115161.7.32.0/20161.7.32.1 to 161.7.47.254161.7.47.2554,094
116161.7.48.0/20161.7.48.1 to 161.7.63.254161.7.63.2554,094
117161.7.64.0/20161.7.64.1 to 161.7.79.254161.7.79.2554,094
118161.7.80.0/20161.7.80.1 to 161.7.95.254161.7.95.2554,094
119161.7.96.0/20161.7.96.1 to 161.7.111.254161.7.111.2554,094
120161.7.112.0/20161.7.112.1 to 161.7.127.254161.7.127.2554,094
121161.7.128.0/20161.7.128.1 to 161.7.143.254161.7.143.2554,094
122161.7.144.0/20161.7.144.1 to 161.7.159.254161.7.159.2554,094
123161.7.160.0/20161.7.160.1 to 161.7.175.254161.7.175.2554,094
124161.7.176.0/20161.7.176.1 to 161.7.191.254161.7.191.2554,094
125161.7.192.0/20161.7.192.1 to 161.7.207.254161.7.207.2554,094
126161.7.208.0/20161.7.208.1 to 161.7.223.254161.7.223.2554,094
127161.7.224.0/20161.7.224.1 to 161.7.239.254161.7.239.2554,094
128161.7.240.0/20161.7.240.1 to 161.7.255.254161.7.255.2554,094
129161.8.0.0/20161.8.0.1 to 161.8.15.254161.8.15.2554,094
130161.8.16.0/20161.8.16.1 to 161.8.31.254161.8.31.2554,094
131161.8.32.0/20161.8.32.1 to 161.8.47.254161.8.47.2554,094
132161.8.48.0/20161.8.48.1 to 161.8.63.254161.8.63.2554,094
133161.8.64.0/20161.8.64.1 to 161.8.79.254161.8.79.2554,094
134161.8.80.0/20161.8.80.1 to 161.8.95.254161.8.95.2554,094
135161.8.96.0/20161.8.96.1 to 161.8.111.254161.8.111.2554,094
136161.8.112.0/20161.8.112.1 to 161.8.127.254161.8.127.2554,094
137161.8.128.0/20161.8.128.1 to 161.8.143.254161.8.143.2554,094
138161.8.144.0/20161.8.144.1 to 161.8.159.254161.8.159.2554,094
139161.8.160.0/20161.8.160.1 to 161.8.175.254161.8.175.2554,094
140161.8.176.0/20161.8.176.1 to 161.8.191.254161.8.191.2554,094
141161.8.192.0/20161.8.192.1 to 161.8.207.254161.8.207.2554,094
142161.8.208.0/20161.8.208.1 to 161.8.223.254161.8.223.2554,094
143161.8.224.0/20161.8.224.1 to 161.8.239.254161.8.239.2554,094
144161.8.240.0/20161.8.240.1 to 161.8.255.254161.8.255.2554,094
145161.9.0.0/20161.9.0.1 to 161.9.15.254161.9.15.2554,094
146161.9.16.0/20161.9.16.1 to 161.9.31.254161.9.31.2554,094
147161.9.32.0/20161.9.32.1 to 161.9.47.254161.9.47.2554,094
148161.9.48.0/20161.9.48.1 to 161.9.63.254161.9.63.2554,094
149161.9.64.0/20161.9.64.1 to 161.9.79.254161.9.79.2554,094
150161.9.80.0/20161.9.80.1 to 161.9.95.254161.9.95.2554,094
151161.9.96.0/20161.9.96.1 to 161.9.111.254161.9.111.2554,094
152161.9.112.0/20161.9.112.1 to 161.9.127.254161.9.127.2554,094
153161.9.128.0/20161.9.128.1 to 161.9.143.254161.9.143.2554,094
154161.9.144.0/20161.9.144.1 to 161.9.159.254161.9.159.2554,094
155161.9.160.0/20161.9.160.1 to 161.9.175.254161.9.175.2554,094
156161.9.176.0/20161.9.176.1 to 161.9.191.254161.9.191.2554,094
157161.9.192.0/20161.9.192.1 to 161.9.207.254161.9.207.2554,094
158161.9.208.0/20161.9.208.1 to 161.9.223.254161.9.223.2554,094
159161.9.224.0/20161.9.224.1 to 161.9.239.254161.9.239.2554,094
160161.9.240.0/20161.9.240.1 to 161.9.255.254161.9.255.2554,094
161161.10.0.0/20161.10.0.1 to 161.10.15.254161.10.15.2554,094
162161.10.16.0/20161.10.16.1 to 161.10.31.254161.10.31.2554,094
163161.10.32.0/20161.10.32.1 to 161.10.47.254161.10.47.2554,094
164161.10.48.0/20161.10.48.1 to 161.10.63.254161.10.63.2554,094
165161.10.64.0/20161.10.64.1 to 161.10.79.254161.10.79.2554,094
166161.10.80.0/20161.10.80.1 to 161.10.95.254161.10.95.2554,094
167161.10.96.0/20161.10.96.1 to 161.10.111.254161.10.111.2554,094
168161.10.112.0/20161.10.112.1 to 161.10.127.254161.10.127.2554,094
169161.10.128.0/20161.10.128.1 to 161.10.143.254161.10.143.2554,094
170161.10.144.0/20161.10.144.1 to 161.10.159.254161.10.159.2554,094
171161.10.160.0/20161.10.160.1 to 161.10.175.254161.10.175.2554,094
172161.10.176.0/20161.10.176.1 to 161.10.191.254161.10.191.2554,094
173161.10.192.0/20161.10.192.1 to 161.10.207.254161.10.207.2554,094
174161.10.208.0/20161.10.208.1 to 161.10.223.254161.10.223.2554,094
175161.10.224.0/20161.10.224.1 to 161.10.239.254161.10.239.2554,094
176161.10.240.0/20161.10.240.1 to 161.10.255.254161.10.255.2554,094
177161.11.0.0/20161.11.0.1 to 161.11.15.254161.11.15.2554,094
178161.11.16.0/20161.11.16.1 to 161.11.31.254161.11.31.2554,094
179161.11.32.0/20161.11.32.1 to 161.11.47.254161.11.47.2554,094
180161.11.48.0/20161.11.48.1 to 161.11.63.254161.11.63.2554,094
181161.11.64.0/20161.11.64.1 to 161.11.79.254161.11.79.2554,094
182161.11.80.0/20161.11.80.1 to 161.11.95.254161.11.95.2554,094
183161.11.96.0/20161.11.96.1 to 161.11.111.254161.11.111.2554,094
184161.11.112.0/20161.11.112.1 to 161.11.127.254161.11.127.2554,094
185161.11.128.0/20161.11.128.1 to 161.11.143.254161.11.143.2554,094
186161.11.144.0/20161.11.144.1 to 161.11.159.254161.11.159.2554,094
187161.11.160.0/20161.11.160.1 to 161.11.175.254161.11.175.2554,094
188161.11.176.0/20161.11.176.1 to 161.11.191.254161.11.191.2554,094
189161.11.192.0/20161.11.192.1 to 161.11.207.254161.11.207.2554,094
190161.11.208.0/20161.11.208.1 to 161.11.223.254161.11.223.2554,094
191161.11.224.0/20161.11.224.1 to 161.11.239.254161.11.239.2554,094
192161.11.240.0/20161.11.240.1 to 161.11.255.254161.11.255.2554,094
193161.12.0.0/20161.12.0.1 to 161.12.15.254161.12.15.2554,094
194161.12.16.0/20161.12.16.1 to 161.12.31.254161.12.31.2554,094
195161.12.32.0/20161.12.32.1 to 161.12.47.254161.12.47.2554,094
196161.12.48.0/20161.12.48.1 to 161.12.63.254161.12.63.2554,094
197161.12.64.0/20161.12.64.1 to 161.12.79.254161.12.79.2554,094
198161.12.80.0/20161.12.80.1 to 161.12.95.254161.12.95.2554,094
199161.12.96.0/20161.12.96.1 to 161.12.111.254161.12.111.2554,094
200161.12.112.0/20161.12.112.1 to 161.12.127.254161.12.127.2554,094
201161.12.128.0/20161.12.128.1 to 161.12.143.254161.12.143.2554,094
202161.12.144.0/20161.12.144.1 to 161.12.159.254161.12.159.2554,094
203161.12.160.0/20161.12.160.1 to 161.12.175.254161.12.175.2554,094
204161.12.176.0/20161.12.176.1 to 161.12.191.254161.12.191.2554,094
205161.12.192.0/20161.12.192.1 to 161.12.207.254161.12.207.2554,094
206161.12.208.0/20161.12.208.1 to 161.12.223.254161.12.223.2554,094
207161.12.224.0/20161.12.224.1 to 161.12.239.254161.12.239.2554,094
208161.12.240.0/20161.12.240.1 to 161.12.255.254161.12.255.2554,094
209161.13.0.0/20161.13.0.1 to 161.13.15.254161.13.15.2554,094
210161.13.16.0/20161.13.16.1 to 161.13.31.254161.13.31.2554,094
211161.13.32.0/20161.13.32.1 to 161.13.47.254161.13.47.2554,094
212161.13.48.0/20161.13.48.1 to 161.13.63.254161.13.63.2554,094
213161.13.64.0/20161.13.64.1 to 161.13.79.254161.13.79.2554,094
214161.13.80.0/20161.13.80.1 to 161.13.95.254161.13.95.2554,094
215161.13.96.0/20161.13.96.1 to 161.13.111.254161.13.111.2554,094
216161.13.112.0/20161.13.112.1 to 161.13.127.254161.13.127.2554,094
217161.13.128.0/20161.13.128.1 to 161.13.143.254161.13.143.2554,094
218161.13.144.0/20161.13.144.1 to 161.13.159.254161.13.159.2554,094
219161.13.160.0/20161.13.160.1 to 161.13.175.254161.13.175.2554,094
220161.13.176.0/20161.13.176.1 to 161.13.191.254161.13.191.2554,094
221161.13.192.0/20161.13.192.1 to 161.13.207.254161.13.207.2554,094
222161.13.208.0/20161.13.208.1 to 161.13.223.254161.13.223.2554,094
223161.13.224.0/20161.13.224.1 to 161.13.239.254161.13.239.2554,094
224161.13.240.0/20161.13.240.1 to 161.13.255.254161.13.255.2554,094
225161.14.0.0/20161.14.0.1 to 161.14.15.254161.14.15.2554,094
226161.14.16.0/20161.14.16.1 to 161.14.31.254161.14.31.2554,094
227161.14.32.0/20161.14.32.1 to 161.14.47.254161.14.47.2554,094
228161.14.48.0/20161.14.48.1 to 161.14.63.254161.14.63.2554,094
229161.14.64.0/20161.14.64.1 to 161.14.79.254161.14.79.2554,094
230161.14.80.0/20161.14.80.1 to 161.14.95.254161.14.95.2554,094
231161.14.96.0/20161.14.96.1 to 161.14.111.254161.14.111.2554,094
232161.14.112.0/20161.14.112.1 to 161.14.127.254161.14.127.2554,094
233161.14.128.0/20161.14.128.1 to 161.14.143.254161.14.143.2554,094
234161.14.144.0/20161.14.144.1 to 161.14.159.254161.14.159.2554,094
235161.14.160.0/20161.14.160.1 to 161.14.175.254161.14.175.2554,094
236161.14.176.0/20161.14.176.1 to 161.14.191.254161.14.191.2554,094
237161.14.192.0/20161.14.192.1 to 161.14.207.254161.14.207.2554,094
238161.14.208.0/20161.14.208.1 to 161.14.223.254161.14.223.2554,094
239161.14.224.0/20161.14.224.1 to 161.14.239.254161.14.239.2554,094
240161.14.240.0/20161.14.240.1 to 161.14.255.254161.14.255.2554,094
241161.15.0.0/20161.15.0.1 to 161.15.15.254161.15.15.2554,094
242161.15.16.0/20161.15.16.1 to 161.15.31.254161.15.31.2554,094
243161.15.32.0/20161.15.32.1 to 161.15.47.254161.15.47.2554,094
244161.15.48.0/20161.15.48.1 to 161.15.63.254161.15.63.2554,094
245161.15.64.0/20161.15.64.1 to 161.15.79.254161.15.79.2554,094
246161.15.80.0/20161.15.80.1 to 161.15.95.254161.15.95.2554,094
247161.15.96.0/20161.15.96.1 to 161.15.111.254161.15.111.2554,094
248161.15.112.0/20161.15.112.1 to 161.15.127.254161.15.127.2554,094
249161.15.128.0/20161.15.128.1 to 161.15.143.254161.15.143.2554,094
250161.15.144.0/20161.15.144.1 to 161.15.159.254161.15.159.2554,094
251161.15.160.0/20161.15.160.1 to 161.15.175.254161.15.175.2554,094
252161.15.176.0/20161.15.176.1 to 161.15.191.254161.15.191.2554,094
253161.15.192.0/20161.15.192.1 to 161.15.207.254161.15.207.2554,094
254161.15.208.0/20161.15.208.1 to 161.15.223.254161.15.223.2554,094
255161.15.224.0/20161.15.224.1 to 161.15.239.254161.15.239.2554,094
256161.15.240.0/20161.15.240.1 to 161.15.255.254161.15.255.2554,094

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.