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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.

Network171.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
171.0.0.0
Broadcast address
171.255.255.255
First usable
171.0.0.1
Last usable
171.255.255.254
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 AB000000 · Integer 2868903936 to 2885681151
Reverse DNS zone
171.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10101011..00000000.00000000.00000000171.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network10101011..00000000.00000000.00000000171.0.0.0
Broadcast10101011..11111111.11111111.11111111171.255.255.255
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)

171.0.0.0/8 makes 4,096 subnets of /20; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1171.0.0.0/20171.0.0.1 to 171.0.15.254171.0.15.2554,094
2171.0.16.0/20171.0.16.1 to 171.0.31.254171.0.31.2554,094
3171.0.32.0/20171.0.32.1 to 171.0.47.254171.0.47.2554,094
4171.0.48.0/20171.0.48.1 to 171.0.63.254171.0.63.2554,094
5171.0.64.0/20171.0.64.1 to 171.0.79.254171.0.79.2554,094
6171.0.80.0/20171.0.80.1 to 171.0.95.254171.0.95.2554,094
7171.0.96.0/20171.0.96.1 to 171.0.111.254171.0.111.2554,094
8171.0.112.0/20171.0.112.1 to 171.0.127.254171.0.127.2554,094
9171.0.128.0/20171.0.128.1 to 171.0.143.254171.0.143.2554,094
10171.0.144.0/20171.0.144.1 to 171.0.159.254171.0.159.2554,094
11171.0.160.0/20171.0.160.1 to 171.0.175.254171.0.175.2554,094
12171.0.176.0/20171.0.176.1 to 171.0.191.254171.0.191.2554,094
13171.0.192.0/20171.0.192.1 to 171.0.207.254171.0.207.2554,094
14171.0.208.0/20171.0.208.1 to 171.0.223.254171.0.223.2554,094
15171.0.224.0/20171.0.224.1 to 171.0.239.254171.0.239.2554,094
16171.0.240.0/20171.0.240.1 to 171.0.255.254171.0.255.2554,094
17171.1.0.0/20171.1.0.1 to 171.1.15.254171.1.15.2554,094
18171.1.16.0/20171.1.16.1 to 171.1.31.254171.1.31.2554,094
19171.1.32.0/20171.1.32.1 to 171.1.47.254171.1.47.2554,094
20171.1.48.0/20171.1.48.1 to 171.1.63.254171.1.63.2554,094
21171.1.64.0/20171.1.64.1 to 171.1.79.254171.1.79.2554,094
22171.1.80.0/20171.1.80.1 to 171.1.95.254171.1.95.2554,094
23171.1.96.0/20171.1.96.1 to 171.1.111.254171.1.111.2554,094
24171.1.112.0/20171.1.112.1 to 171.1.127.254171.1.127.2554,094
25171.1.128.0/20171.1.128.1 to 171.1.143.254171.1.143.2554,094
26171.1.144.0/20171.1.144.1 to 171.1.159.254171.1.159.2554,094
27171.1.160.0/20171.1.160.1 to 171.1.175.254171.1.175.2554,094
28171.1.176.0/20171.1.176.1 to 171.1.191.254171.1.191.2554,094
29171.1.192.0/20171.1.192.1 to 171.1.207.254171.1.207.2554,094
30171.1.208.0/20171.1.208.1 to 171.1.223.254171.1.223.2554,094
31171.1.224.0/20171.1.224.1 to 171.1.239.254171.1.239.2554,094
32171.1.240.0/20171.1.240.1 to 171.1.255.254171.1.255.2554,094
33171.2.0.0/20171.2.0.1 to 171.2.15.254171.2.15.2554,094
34171.2.16.0/20171.2.16.1 to 171.2.31.254171.2.31.2554,094
35171.2.32.0/20171.2.32.1 to 171.2.47.254171.2.47.2554,094
36171.2.48.0/20171.2.48.1 to 171.2.63.254171.2.63.2554,094
37171.2.64.0/20171.2.64.1 to 171.2.79.254171.2.79.2554,094
38171.2.80.0/20171.2.80.1 to 171.2.95.254171.2.95.2554,094
39171.2.96.0/20171.2.96.1 to 171.2.111.254171.2.111.2554,094
40171.2.112.0/20171.2.112.1 to 171.2.127.254171.2.127.2554,094
41171.2.128.0/20171.2.128.1 to 171.2.143.254171.2.143.2554,094
42171.2.144.0/20171.2.144.1 to 171.2.159.254171.2.159.2554,094
43171.2.160.0/20171.2.160.1 to 171.2.175.254171.2.175.2554,094
44171.2.176.0/20171.2.176.1 to 171.2.191.254171.2.191.2554,094
45171.2.192.0/20171.2.192.1 to 171.2.207.254171.2.207.2554,094
46171.2.208.0/20171.2.208.1 to 171.2.223.254171.2.223.2554,094
47171.2.224.0/20171.2.224.1 to 171.2.239.254171.2.239.2554,094
48171.2.240.0/20171.2.240.1 to 171.2.255.254171.2.255.2554,094
49171.3.0.0/20171.3.0.1 to 171.3.15.254171.3.15.2554,094
50171.3.16.0/20171.3.16.1 to 171.3.31.254171.3.31.2554,094
51171.3.32.0/20171.3.32.1 to 171.3.47.254171.3.47.2554,094
52171.3.48.0/20171.3.48.1 to 171.3.63.254171.3.63.2554,094
53171.3.64.0/20171.3.64.1 to 171.3.79.254171.3.79.2554,094
54171.3.80.0/20171.3.80.1 to 171.3.95.254171.3.95.2554,094
55171.3.96.0/20171.3.96.1 to 171.3.111.254171.3.111.2554,094
56171.3.112.0/20171.3.112.1 to 171.3.127.254171.3.127.2554,094
57171.3.128.0/20171.3.128.1 to 171.3.143.254171.3.143.2554,094
58171.3.144.0/20171.3.144.1 to 171.3.159.254171.3.159.2554,094
59171.3.160.0/20171.3.160.1 to 171.3.175.254171.3.175.2554,094
60171.3.176.0/20171.3.176.1 to 171.3.191.254171.3.191.2554,094
61171.3.192.0/20171.3.192.1 to 171.3.207.254171.3.207.2554,094
62171.3.208.0/20171.3.208.1 to 171.3.223.254171.3.223.2554,094
63171.3.224.0/20171.3.224.1 to 171.3.239.254171.3.239.2554,094
64171.3.240.0/20171.3.240.1 to 171.3.255.254171.3.255.2554,094
65171.4.0.0/20171.4.0.1 to 171.4.15.254171.4.15.2554,094
66171.4.16.0/20171.4.16.1 to 171.4.31.254171.4.31.2554,094
67171.4.32.0/20171.4.32.1 to 171.4.47.254171.4.47.2554,094
68171.4.48.0/20171.4.48.1 to 171.4.63.254171.4.63.2554,094
69171.4.64.0/20171.4.64.1 to 171.4.79.254171.4.79.2554,094
70171.4.80.0/20171.4.80.1 to 171.4.95.254171.4.95.2554,094
71171.4.96.0/20171.4.96.1 to 171.4.111.254171.4.111.2554,094
72171.4.112.0/20171.4.112.1 to 171.4.127.254171.4.127.2554,094
73171.4.128.0/20171.4.128.1 to 171.4.143.254171.4.143.2554,094
74171.4.144.0/20171.4.144.1 to 171.4.159.254171.4.159.2554,094
75171.4.160.0/20171.4.160.1 to 171.4.175.254171.4.175.2554,094
76171.4.176.0/20171.4.176.1 to 171.4.191.254171.4.191.2554,094
77171.4.192.0/20171.4.192.1 to 171.4.207.254171.4.207.2554,094
78171.4.208.0/20171.4.208.1 to 171.4.223.254171.4.223.2554,094
79171.4.224.0/20171.4.224.1 to 171.4.239.254171.4.239.2554,094
80171.4.240.0/20171.4.240.1 to 171.4.255.254171.4.255.2554,094
81171.5.0.0/20171.5.0.1 to 171.5.15.254171.5.15.2554,094
82171.5.16.0/20171.5.16.1 to 171.5.31.254171.5.31.2554,094
83171.5.32.0/20171.5.32.1 to 171.5.47.254171.5.47.2554,094
84171.5.48.0/20171.5.48.1 to 171.5.63.254171.5.63.2554,094
85171.5.64.0/20171.5.64.1 to 171.5.79.254171.5.79.2554,094
86171.5.80.0/20171.5.80.1 to 171.5.95.254171.5.95.2554,094
87171.5.96.0/20171.5.96.1 to 171.5.111.254171.5.111.2554,094
88171.5.112.0/20171.5.112.1 to 171.5.127.254171.5.127.2554,094
89171.5.128.0/20171.5.128.1 to 171.5.143.254171.5.143.2554,094
90171.5.144.0/20171.5.144.1 to 171.5.159.254171.5.159.2554,094
91171.5.160.0/20171.5.160.1 to 171.5.175.254171.5.175.2554,094
92171.5.176.0/20171.5.176.1 to 171.5.191.254171.5.191.2554,094
93171.5.192.0/20171.5.192.1 to 171.5.207.254171.5.207.2554,094
94171.5.208.0/20171.5.208.1 to 171.5.223.254171.5.223.2554,094
95171.5.224.0/20171.5.224.1 to 171.5.239.254171.5.239.2554,094
96171.5.240.0/20171.5.240.1 to 171.5.255.254171.5.255.2554,094
97171.6.0.0/20171.6.0.1 to 171.6.15.254171.6.15.2554,094
98171.6.16.0/20171.6.16.1 to 171.6.31.254171.6.31.2554,094
99171.6.32.0/20171.6.32.1 to 171.6.47.254171.6.47.2554,094
100171.6.48.0/20171.6.48.1 to 171.6.63.254171.6.63.2554,094
101171.6.64.0/20171.6.64.1 to 171.6.79.254171.6.79.2554,094
102171.6.80.0/20171.6.80.1 to 171.6.95.254171.6.95.2554,094
103171.6.96.0/20171.6.96.1 to 171.6.111.254171.6.111.2554,094
104171.6.112.0/20171.6.112.1 to 171.6.127.254171.6.127.2554,094
105171.6.128.0/20171.6.128.1 to 171.6.143.254171.6.143.2554,094
106171.6.144.0/20171.6.144.1 to 171.6.159.254171.6.159.2554,094
107171.6.160.0/20171.6.160.1 to 171.6.175.254171.6.175.2554,094
108171.6.176.0/20171.6.176.1 to 171.6.191.254171.6.191.2554,094
109171.6.192.0/20171.6.192.1 to 171.6.207.254171.6.207.2554,094
110171.6.208.0/20171.6.208.1 to 171.6.223.254171.6.223.2554,094
111171.6.224.0/20171.6.224.1 to 171.6.239.254171.6.239.2554,094
112171.6.240.0/20171.6.240.1 to 171.6.255.254171.6.255.2554,094
113171.7.0.0/20171.7.0.1 to 171.7.15.254171.7.15.2554,094
114171.7.16.0/20171.7.16.1 to 171.7.31.254171.7.31.2554,094
115171.7.32.0/20171.7.32.1 to 171.7.47.254171.7.47.2554,094
116171.7.48.0/20171.7.48.1 to 171.7.63.254171.7.63.2554,094
117171.7.64.0/20171.7.64.1 to 171.7.79.254171.7.79.2554,094
118171.7.80.0/20171.7.80.1 to 171.7.95.254171.7.95.2554,094
119171.7.96.0/20171.7.96.1 to 171.7.111.254171.7.111.2554,094
120171.7.112.0/20171.7.112.1 to 171.7.127.254171.7.127.2554,094
121171.7.128.0/20171.7.128.1 to 171.7.143.254171.7.143.2554,094
122171.7.144.0/20171.7.144.1 to 171.7.159.254171.7.159.2554,094
123171.7.160.0/20171.7.160.1 to 171.7.175.254171.7.175.2554,094
124171.7.176.0/20171.7.176.1 to 171.7.191.254171.7.191.2554,094
125171.7.192.0/20171.7.192.1 to 171.7.207.254171.7.207.2554,094
126171.7.208.0/20171.7.208.1 to 171.7.223.254171.7.223.2554,094
127171.7.224.0/20171.7.224.1 to 171.7.239.254171.7.239.2554,094
128171.7.240.0/20171.7.240.1 to 171.7.255.254171.7.255.2554,094
129171.8.0.0/20171.8.0.1 to 171.8.15.254171.8.15.2554,094
130171.8.16.0/20171.8.16.1 to 171.8.31.254171.8.31.2554,094
131171.8.32.0/20171.8.32.1 to 171.8.47.254171.8.47.2554,094
132171.8.48.0/20171.8.48.1 to 171.8.63.254171.8.63.2554,094
133171.8.64.0/20171.8.64.1 to 171.8.79.254171.8.79.2554,094
134171.8.80.0/20171.8.80.1 to 171.8.95.254171.8.95.2554,094
135171.8.96.0/20171.8.96.1 to 171.8.111.254171.8.111.2554,094
136171.8.112.0/20171.8.112.1 to 171.8.127.254171.8.127.2554,094
137171.8.128.0/20171.8.128.1 to 171.8.143.254171.8.143.2554,094
138171.8.144.0/20171.8.144.1 to 171.8.159.254171.8.159.2554,094
139171.8.160.0/20171.8.160.1 to 171.8.175.254171.8.175.2554,094
140171.8.176.0/20171.8.176.1 to 171.8.191.254171.8.191.2554,094
141171.8.192.0/20171.8.192.1 to 171.8.207.254171.8.207.2554,094
142171.8.208.0/20171.8.208.1 to 171.8.223.254171.8.223.2554,094
143171.8.224.0/20171.8.224.1 to 171.8.239.254171.8.239.2554,094
144171.8.240.0/20171.8.240.1 to 171.8.255.254171.8.255.2554,094
145171.9.0.0/20171.9.0.1 to 171.9.15.254171.9.15.2554,094
146171.9.16.0/20171.9.16.1 to 171.9.31.254171.9.31.2554,094
147171.9.32.0/20171.9.32.1 to 171.9.47.254171.9.47.2554,094
148171.9.48.0/20171.9.48.1 to 171.9.63.254171.9.63.2554,094
149171.9.64.0/20171.9.64.1 to 171.9.79.254171.9.79.2554,094
150171.9.80.0/20171.9.80.1 to 171.9.95.254171.9.95.2554,094
151171.9.96.0/20171.9.96.1 to 171.9.111.254171.9.111.2554,094
152171.9.112.0/20171.9.112.1 to 171.9.127.254171.9.127.2554,094
153171.9.128.0/20171.9.128.1 to 171.9.143.254171.9.143.2554,094
154171.9.144.0/20171.9.144.1 to 171.9.159.254171.9.159.2554,094
155171.9.160.0/20171.9.160.1 to 171.9.175.254171.9.175.2554,094
156171.9.176.0/20171.9.176.1 to 171.9.191.254171.9.191.2554,094
157171.9.192.0/20171.9.192.1 to 171.9.207.254171.9.207.2554,094
158171.9.208.0/20171.9.208.1 to 171.9.223.254171.9.223.2554,094
159171.9.224.0/20171.9.224.1 to 171.9.239.254171.9.239.2554,094
160171.9.240.0/20171.9.240.1 to 171.9.255.254171.9.255.2554,094
161171.10.0.0/20171.10.0.1 to 171.10.15.254171.10.15.2554,094
162171.10.16.0/20171.10.16.1 to 171.10.31.254171.10.31.2554,094
163171.10.32.0/20171.10.32.1 to 171.10.47.254171.10.47.2554,094
164171.10.48.0/20171.10.48.1 to 171.10.63.254171.10.63.2554,094
165171.10.64.0/20171.10.64.1 to 171.10.79.254171.10.79.2554,094
166171.10.80.0/20171.10.80.1 to 171.10.95.254171.10.95.2554,094
167171.10.96.0/20171.10.96.1 to 171.10.111.254171.10.111.2554,094
168171.10.112.0/20171.10.112.1 to 171.10.127.254171.10.127.2554,094
169171.10.128.0/20171.10.128.1 to 171.10.143.254171.10.143.2554,094
170171.10.144.0/20171.10.144.1 to 171.10.159.254171.10.159.2554,094
171171.10.160.0/20171.10.160.1 to 171.10.175.254171.10.175.2554,094
172171.10.176.0/20171.10.176.1 to 171.10.191.254171.10.191.2554,094
173171.10.192.0/20171.10.192.1 to 171.10.207.254171.10.207.2554,094
174171.10.208.0/20171.10.208.1 to 171.10.223.254171.10.223.2554,094
175171.10.224.0/20171.10.224.1 to 171.10.239.254171.10.239.2554,094
176171.10.240.0/20171.10.240.1 to 171.10.255.254171.10.255.2554,094
177171.11.0.0/20171.11.0.1 to 171.11.15.254171.11.15.2554,094
178171.11.16.0/20171.11.16.1 to 171.11.31.254171.11.31.2554,094
179171.11.32.0/20171.11.32.1 to 171.11.47.254171.11.47.2554,094
180171.11.48.0/20171.11.48.1 to 171.11.63.254171.11.63.2554,094
181171.11.64.0/20171.11.64.1 to 171.11.79.254171.11.79.2554,094
182171.11.80.0/20171.11.80.1 to 171.11.95.254171.11.95.2554,094
183171.11.96.0/20171.11.96.1 to 171.11.111.254171.11.111.2554,094
184171.11.112.0/20171.11.112.1 to 171.11.127.254171.11.127.2554,094
185171.11.128.0/20171.11.128.1 to 171.11.143.254171.11.143.2554,094
186171.11.144.0/20171.11.144.1 to 171.11.159.254171.11.159.2554,094
187171.11.160.0/20171.11.160.1 to 171.11.175.254171.11.175.2554,094
188171.11.176.0/20171.11.176.1 to 171.11.191.254171.11.191.2554,094
189171.11.192.0/20171.11.192.1 to 171.11.207.254171.11.207.2554,094
190171.11.208.0/20171.11.208.1 to 171.11.223.254171.11.223.2554,094
191171.11.224.0/20171.11.224.1 to 171.11.239.254171.11.239.2554,094
192171.11.240.0/20171.11.240.1 to 171.11.255.254171.11.255.2554,094
193171.12.0.0/20171.12.0.1 to 171.12.15.254171.12.15.2554,094
194171.12.16.0/20171.12.16.1 to 171.12.31.254171.12.31.2554,094
195171.12.32.0/20171.12.32.1 to 171.12.47.254171.12.47.2554,094
196171.12.48.0/20171.12.48.1 to 171.12.63.254171.12.63.2554,094
197171.12.64.0/20171.12.64.1 to 171.12.79.254171.12.79.2554,094
198171.12.80.0/20171.12.80.1 to 171.12.95.254171.12.95.2554,094
199171.12.96.0/20171.12.96.1 to 171.12.111.254171.12.111.2554,094
200171.12.112.0/20171.12.112.1 to 171.12.127.254171.12.127.2554,094
201171.12.128.0/20171.12.128.1 to 171.12.143.254171.12.143.2554,094
202171.12.144.0/20171.12.144.1 to 171.12.159.254171.12.159.2554,094
203171.12.160.0/20171.12.160.1 to 171.12.175.254171.12.175.2554,094
204171.12.176.0/20171.12.176.1 to 171.12.191.254171.12.191.2554,094
205171.12.192.0/20171.12.192.1 to 171.12.207.254171.12.207.2554,094
206171.12.208.0/20171.12.208.1 to 171.12.223.254171.12.223.2554,094
207171.12.224.0/20171.12.224.1 to 171.12.239.254171.12.239.2554,094
208171.12.240.0/20171.12.240.1 to 171.12.255.254171.12.255.2554,094
209171.13.0.0/20171.13.0.1 to 171.13.15.254171.13.15.2554,094
210171.13.16.0/20171.13.16.1 to 171.13.31.254171.13.31.2554,094
211171.13.32.0/20171.13.32.1 to 171.13.47.254171.13.47.2554,094
212171.13.48.0/20171.13.48.1 to 171.13.63.254171.13.63.2554,094
213171.13.64.0/20171.13.64.1 to 171.13.79.254171.13.79.2554,094
214171.13.80.0/20171.13.80.1 to 171.13.95.254171.13.95.2554,094
215171.13.96.0/20171.13.96.1 to 171.13.111.254171.13.111.2554,094
216171.13.112.0/20171.13.112.1 to 171.13.127.254171.13.127.2554,094
217171.13.128.0/20171.13.128.1 to 171.13.143.254171.13.143.2554,094
218171.13.144.0/20171.13.144.1 to 171.13.159.254171.13.159.2554,094
219171.13.160.0/20171.13.160.1 to 171.13.175.254171.13.175.2554,094
220171.13.176.0/20171.13.176.1 to 171.13.191.254171.13.191.2554,094
221171.13.192.0/20171.13.192.1 to 171.13.207.254171.13.207.2554,094
222171.13.208.0/20171.13.208.1 to 171.13.223.254171.13.223.2554,094
223171.13.224.0/20171.13.224.1 to 171.13.239.254171.13.239.2554,094
224171.13.240.0/20171.13.240.1 to 171.13.255.254171.13.255.2554,094
225171.14.0.0/20171.14.0.1 to 171.14.15.254171.14.15.2554,094
226171.14.16.0/20171.14.16.1 to 171.14.31.254171.14.31.2554,094
227171.14.32.0/20171.14.32.1 to 171.14.47.254171.14.47.2554,094
228171.14.48.0/20171.14.48.1 to 171.14.63.254171.14.63.2554,094
229171.14.64.0/20171.14.64.1 to 171.14.79.254171.14.79.2554,094
230171.14.80.0/20171.14.80.1 to 171.14.95.254171.14.95.2554,094
231171.14.96.0/20171.14.96.1 to 171.14.111.254171.14.111.2554,094
232171.14.112.0/20171.14.112.1 to 171.14.127.254171.14.127.2554,094
233171.14.128.0/20171.14.128.1 to 171.14.143.254171.14.143.2554,094
234171.14.144.0/20171.14.144.1 to 171.14.159.254171.14.159.2554,094
235171.14.160.0/20171.14.160.1 to 171.14.175.254171.14.175.2554,094
236171.14.176.0/20171.14.176.1 to 171.14.191.254171.14.191.2554,094
237171.14.192.0/20171.14.192.1 to 171.14.207.254171.14.207.2554,094
238171.14.208.0/20171.14.208.1 to 171.14.223.254171.14.223.2554,094
239171.14.224.0/20171.14.224.1 to 171.14.239.254171.14.239.2554,094
240171.14.240.0/20171.14.240.1 to 171.14.255.254171.14.255.2554,094
241171.15.0.0/20171.15.0.1 to 171.15.15.254171.15.15.2554,094
242171.15.16.0/20171.15.16.1 to 171.15.31.254171.15.31.2554,094
243171.15.32.0/20171.15.32.1 to 171.15.47.254171.15.47.2554,094
244171.15.48.0/20171.15.48.1 to 171.15.63.254171.15.63.2554,094
245171.15.64.0/20171.15.64.1 to 171.15.79.254171.15.79.2554,094
246171.15.80.0/20171.15.80.1 to 171.15.95.254171.15.95.2554,094
247171.15.96.0/20171.15.96.1 to 171.15.111.254171.15.111.2554,094
248171.15.112.0/20171.15.112.1 to 171.15.127.254171.15.127.2554,094
249171.15.128.0/20171.15.128.1 to 171.15.143.254171.15.143.2554,094
250171.15.144.0/20171.15.144.1 to 171.15.159.254171.15.159.2554,094
251171.15.160.0/20171.15.160.1 to 171.15.175.254171.15.175.2554,094
252171.15.176.0/20171.15.176.1 to 171.15.191.254171.15.191.2554,094
253171.15.192.0/20171.15.192.1 to 171.15.207.254171.15.207.2554,094
254171.15.208.0/20171.15.208.1 to 171.15.223.254171.15.223.2554,094
255171.15.224.0/20171.15.224.1 to 171.15.239.254171.15.239.2554,094
256171.15.240.0/20171.15.240.1 to 171.15.255.254171.15.255.2554,094

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.