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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.

Network163.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
163.0.0.0
Broadcast address
163.255.255.255
First usable
163.0.0.1
Last usable
163.255.255.254
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 A3000000 · Integer 2734686208 to 2751463423
Reverse DNS zone
163.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10100011..00000000.00000000.00000000163.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network10100011..00000000.00000000.00000000163.0.0.0
Broadcast10100011..11111111.11111111.11111111163.255.255.255
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)

163.0.0.0/8 makes 4,096 subnets of /20; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1163.0.0.0/20163.0.0.1 to 163.0.15.254163.0.15.2554,094
2163.0.16.0/20163.0.16.1 to 163.0.31.254163.0.31.2554,094
3163.0.32.0/20163.0.32.1 to 163.0.47.254163.0.47.2554,094
4163.0.48.0/20163.0.48.1 to 163.0.63.254163.0.63.2554,094
5163.0.64.0/20163.0.64.1 to 163.0.79.254163.0.79.2554,094
6163.0.80.0/20163.0.80.1 to 163.0.95.254163.0.95.2554,094
7163.0.96.0/20163.0.96.1 to 163.0.111.254163.0.111.2554,094
8163.0.112.0/20163.0.112.1 to 163.0.127.254163.0.127.2554,094
9163.0.128.0/20163.0.128.1 to 163.0.143.254163.0.143.2554,094
10163.0.144.0/20163.0.144.1 to 163.0.159.254163.0.159.2554,094
11163.0.160.0/20163.0.160.1 to 163.0.175.254163.0.175.2554,094
12163.0.176.0/20163.0.176.1 to 163.0.191.254163.0.191.2554,094
13163.0.192.0/20163.0.192.1 to 163.0.207.254163.0.207.2554,094
14163.0.208.0/20163.0.208.1 to 163.0.223.254163.0.223.2554,094
15163.0.224.0/20163.0.224.1 to 163.0.239.254163.0.239.2554,094
16163.0.240.0/20163.0.240.1 to 163.0.255.254163.0.255.2554,094
17163.1.0.0/20163.1.0.1 to 163.1.15.254163.1.15.2554,094
18163.1.16.0/20163.1.16.1 to 163.1.31.254163.1.31.2554,094
19163.1.32.0/20163.1.32.1 to 163.1.47.254163.1.47.2554,094
20163.1.48.0/20163.1.48.1 to 163.1.63.254163.1.63.2554,094
21163.1.64.0/20163.1.64.1 to 163.1.79.254163.1.79.2554,094
22163.1.80.0/20163.1.80.1 to 163.1.95.254163.1.95.2554,094
23163.1.96.0/20163.1.96.1 to 163.1.111.254163.1.111.2554,094
24163.1.112.0/20163.1.112.1 to 163.1.127.254163.1.127.2554,094
25163.1.128.0/20163.1.128.1 to 163.1.143.254163.1.143.2554,094
26163.1.144.0/20163.1.144.1 to 163.1.159.254163.1.159.2554,094
27163.1.160.0/20163.1.160.1 to 163.1.175.254163.1.175.2554,094
28163.1.176.0/20163.1.176.1 to 163.1.191.254163.1.191.2554,094
29163.1.192.0/20163.1.192.1 to 163.1.207.254163.1.207.2554,094
30163.1.208.0/20163.1.208.1 to 163.1.223.254163.1.223.2554,094
31163.1.224.0/20163.1.224.1 to 163.1.239.254163.1.239.2554,094
32163.1.240.0/20163.1.240.1 to 163.1.255.254163.1.255.2554,094
33163.2.0.0/20163.2.0.1 to 163.2.15.254163.2.15.2554,094
34163.2.16.0/20163.2.16.1 to 163.2.31.254163.2.31.2554,094
35163.2.32.0/20163.2.32.1 to 163.2.47.254163.2.47.2554,094
36163.2.48.0/20163.2.48.1 to 163.2.63.254163.2.63.2554,094
37163.2.64.0/20163.2.64.1 to 163.2.79.254163.2.79.2554,094
38163.2.80.0/20163.2.80.1 to 163.2.95.254163.2.95.2554,094
39163.2.96.0/20163.2.96.1 to 163.2.111.254163.2.111.2554,094
40163.2.112.0/20163.2.112.1 to 163.2.127.254163.2.127.2554,094
41163.2.128.0/20163.2.128.1 to 163.2.143.254163.2.143.2554,094
42163.2.144.0/20163.2.144.1 to 163.2.159.254163.2.159.2554,094
43163.2.160.0/20163.2.160.1 to 163.2.175.254163.2.175.2554,094
44163.2.176.0/20163.2.176.1 to 163.2.191.254163.2.191.2554,094
45163.2.192.0/20163.2.192.1 to 163.2.207.254163.2.207.2554,094
46163.2.208.0/20163.2.208.1 to 163.2.223.254163.2.223.2554,094
47163.2.224.0/20163.2.224.1 to 163.2.239.254163.2.239.2554,094
48163.2.240.0/20163.2.240.1 to 163.2.255.254163.2.255.2554,094
49163.3.0.0/20163.3.0.1 to 163.3.15.254163.3.15.2554,094
50163.3.16.0/20163.3.16.1 to 163.3.31.254163.3.31.2554,094
51163.3.32.0/20163.3.32.1 to 163.3.47.254163.3.47.2554,094
52163.3.48.0/20163.3.48.1 to 163.3.63.254163.3.63.2554,094
53163.3.64.0/20163.3.64.1 to 163.3.79.254163.3.79.2554,094
54163.3.80.0/20163.3.80.1 to 163.3.95.254163.3.95.2554,094
55163.3.96.0/20163.3.96.1 to 163.3.111.254163.3.111.2554,094
56163.3.112.0/20163.3.112.1 to 163.3.127.254163.3.127.2554,094
57163.3.128.0/20163.3.128.1 to 163.3.143.254163.3.143.2554,094
58163.3.144.0/20163.3.144.1 to 163.3.159.254163.3.159.2554,094
59163.3.160.0/20163.3.160.1 to 163.3.175.254163.3.175.2554,094
60163.3.176.0/20163.3.176.1 to 163.3.191.254163.3.191.2554,094
61163.3.192.0/20163.3.192.1 to 163.3.207.254163.3.207.2554,094
62163.3.208.0/20163.3.208.1 to 163.3.223.254163.3.223.2554,094
63163.3.224.0/20163.3.224.1 to 163.3.239.254163.3.239.2554,094
64163.3.240.0/20163.3.240.1 to 163.3.255.254163.3.255.2554,094
65163.4.0.0/20163.4.0.1 to 163.4.15.254163.4.15.2554,094
66163.4.16.0/20163.4.16.1 to 163.4.31.254163.4.31.2554,094
67163.4.32.0/20163.4.32.1 to 163.4.47.254163.4.47.2554,094
68163.4.48.0/20163.4.48.1 to 163.4.63.254163.4.63.2554,094
69163.4.64.0/20163.4.64.1 to 163.4.79.254163.4.79.2554,094
70163.4.80.0/20163.4.80.1 to 163.4.95.254163.4.95.2554,094
71163.4.96.0/20163.4.96.1 to 163.4.111.254163.4.111.2554,094
72163.4.112.0/20163.4.112.1 to 163.4.127.254163.4.127.2554,094
73163.4.128.0/20163.4.128.1 to 163.4.143.254163.4.143.2554,094
74163.4.144.0/20163.4.144.1 to 163.4.159.254163.4.159.2554,094
75163.4.160.0/20163.4.160.1 to 163.4.175.254163.4.175.2554,094
76163.4.176.0/20163.4.176.1 to 163.4.191.254163.4.191.2554,094
77163.4.192.0/20163.4.192.1 to 163.4.207.254163.4.207.2554,094
78163.4.208.0/20163.4.208.1 to 163.4.223.254163.4.223.2554,094
79163.4.224.0/20163.4.224.1 to 163.4.239.254163.4.239.2554,094
80163.4.240.0/20163.4.240.1 to 163.4.255.254163.4.255.2554,094
81163.5.0.0/20163.5.0.1 to 163.5.15.254163.5.15.2554,094
82163.5.16.0/20163.5.16.1 to 163.5.31.254163.5.31.2554,094
83163.5.32.0/20163.5.32.1 to 163.5.47.254163.5.47.2554,094
84163.5.48.0/20163.5.48.1 to 163.5.63.254163.5.63.2554,094
85163.5.64.0/20163.5.64.1 to 163.5.79.254163.5.79.2554,094
86163.5.80.0/20163.5.80.1 to 163.5.95.254163.5.95.2554,094
87163.5.96.0/20163.5.96.1 to 163.5.111.254163.5.111.2554,094
88163.5.112.0/20163.5.112.1 to 163.5.127.254163.5.127.2554,094
89163.5.128.0/20163.5.128.1 to 163.5.143.254163.5.143.2554,094
90163.5.144.0/20163.5.144.1 to 163.5.159.254163.5.159.2554,094
91163.5.160.0/20163.5.160.1 to 163.5.175.254163.5.175.2554,094
92163.5.176.0/20163.5.176.1 to 163.5.191.254163.5.191.2554,094
93163.5.192.0/20163.5.192.1 to 163.5.207.254163.5.207.2554,094
94163.5.208.0/20163.5.208.1 to 163.5.223.254163.5.223.2554,094
95163.5.224.0/20163.5.224.1 to 163.5.239.254163.5.239.2554,094
96163.5.240.0/20163.5.240.1 to 163.5.255.254163.5.255.2554,094
97163.6.0.0/20163.6.0.1 to 163.6.15.254163.6.15.2554,094
98163.6.16.0/20163.6.16.1 to 163.6.31.254163.6.31.2554,094
99163.6.32.0/20163.6.32.1 to 163.6.47.254163.6.47.2554,094
100163.6.48.0/20163.6.48.1 to 163.6.63.254163.6.63.2554,094
101163.6.64.0/20163.6.64.1 to 163.6.79.254163.6.79.2554,094
102163.6.80.0/20163.6.80.1 to 163.6.95.254163.6.95.2554,094
103163.6.96.0/20163.6.96.1 to 163.6.111.254163.6.111.2554,094
104163.6.112.0/20163.6.112.1 to 163.6.127.254163.6.127.2554,094
105163.6.128.0/20163.6.128.1 to 163.6.143.254163.6.143.2554,094
106163.6.144.0/20163.6.144.1 to 163.6.159.254163.6.159.2554,094
107163.6.160.0/20163.6.160.1 to 163.6.175.254163.6.175.2554,094
108163.6.176.0/20163.6.176.1 to 163.6.191.254163.6.191.2554,094
109163.6.192.0/20163.6.192.1 to 163.6.207.254163.6.207.2554,094
110163.6.208.0/20163.6.208.1 to 163.6.223.254163.6.223.2554,094
111163.6.224.0/20163.6.224.1 to 163.6.239.254163.6.239.2554,094
112163.6.240.0/20163.6.240.1 to 163.6.255.254163.6.255.2554,094
113163.7.0.0/20163.7.0.1 to 163.7.15.254163.7.15.2554,094
114163.7.16.0/20163.7.16.1 to 163.7.31.254163.7.31.2554,094
115163.7.32.0/20163.7.32.1 to 163.7.47.254163.7.47.2554,094
116163.7.48.0/20163.7.48.1 to 163.7.63.254163.7.63.2554,094
117163.7.64.0/20163.7.64.1 to 163.7.79.254163.7.79.2554,094
118163.7.80.0/20163.7.80.1 to 163.7.95.254163.7.95.2554,094
119163.7.96.0/20163.7.96.1 to 163.7.111.254163.7.111.2554,094
120163.7.112.0/20163.7.112.1 to 163.7.127.254163.7.127.2554,094
121163.7.128.0/20163.7.128.1 to 163.7.143.254163.7.143.2554,094
122163.7.144.0/20163.7.144.1 to 163.7.159.254163.7.159.2554,094
123163.7.160.0/20163.7.160.1 to 163.7.175.254163.7.175.2554,094
124163.7.176.0/20163.7.176.1 to 163.7.191.254163.7.191.2554,094
125163.7.192.0/20163.7.192.1 to 163.7.207.254163.7.207.2554,094
126163.7.208.0/20163.7.208.1 to 163.7.223.254163.7.223.2554,094
127163.7.224.0/20163.7.224.1 to 163.7.239.254163.7.239.2554,094
128163.7.240.0/20163.7.240.1 to 163.7.255.254163.7.255.2554,094
129163.8.0.0/20163.8.0.1 to 163.8.15.254163.8.15.2554,094
130163.8.16.0/20163.8.16.1 to 163.8.31.254163.8.31.2554,094
131163.8.32.0/20163.8.32.1 to 163.8.47.254163.8.47.2554,094
132163.8.48.0/20163.8.48.1 to 163.8.63.254163.8.63.2554,094
133163.8.64.0/20163.8.64.1 to 163.8.79.254163.8.79.2554,094
134163.8.80.0/20163.8.80.1 to 163.8.95.254163.8.95.2554,094
135163.8.96.0/20163.8.96.1 to 163.8.111.254163.8.111.2554,094
136163.8.112.0/20163.8.112.1 to 163.8.127.254163.8.127.2554,094
137163.8.128.0/20163.8.128.1 to 163.8.143.254163.8.143.2554,094
138163.8.144.0/20163.8.144.1 to 163.8.159.254163.8.159.2554,094
139163.8.160.0/20163.8.160.1 to 163.8.175.254163.8.175.2554,094
140163.8.176.0/20163.8.176.1 to 163.8.191.254163.8.191.2554,094
141163.8.192.0/20163.8.192.1 to 163.8.207.254163.8.207.2554,094
142163.8.208.0/20163.8.208.1 to 163.8.223.254163.8.223.2554,094
143163.8.224.0/20163.8.224.1 to 163.8.239.254163.8.239.2554,094
144163.8.240.0/20163.8.240.1 to 163.8.255.254163.8.255.2554,094
145163.9.0.0/20163.9.0.1 to 163.9.15.254163.9.15.2554,094
146163.9.16.0/20163.9.16.1 to 163.9.31.254163.9.31.2554,094
147163.9.32.0/20163.9.32.1 to 163.9.47.254163.9.47.2554,094
148163.9.48.0/20163.9.48.1 to 163.9.63.254163.9.63.2554,094
149163.9.64.0/20163.9.64.1 to 163.9.79.254163.9.79.2554,094
150163.9.80.0/20163.9.80.1 to 163.9.95.254163.9.95.2554,094
151163.9.96.0/20163.9.96.1 to 163.9.111.254163.9.111.2554,094
152163.9.112.0/20163.9.112.1 to 163.9.127.254163.9.127.2554,094
153163.9.128.0/20163.9.128.1 to 163.9.143.254163.9.143.2554,094
154163.9.144.0/20163.9.144.1 to 163.9.159.254163.9.159.2554,094
155163.9.160.0/20163.9.160.1 to 163.9.175.254163.9.175.2554,094
156163.9.176.0/20163.9.176.1 to 163.9.191.254163.9.191.2554,094
157163.9.192.0/20163.9.192.1 to 163.9.207.254163.9.207.2554,094
158163.9.208.0/20163.9.208.1 to 163.9.223.254163.9.223.2554,094
159163.9.224.0/20163.9.224.1 to 163.9.239.254163.9.239.2554,094
160163.9.240.0/20163.9.240.1 to 163.9.255.254163.9.255.2554,094
161163.10.0.0/20163.10.0.1 to 163.10.15.254163.10.15.2554,094
162163.10.16.0/20163.10.16.1 to 163.10.31.254163.10.31.2554,094
163163.10.32.0/20163.10.32.1 to 163.10.47.254163.10.47.2554,094
164163.10.48.0/20163.10.48.1 to 163.10.63.254163.10.63.2554,094
165163.10.64.0/20163.10.64.1 to 163.10.79.254163.10.79.2554,094
166163.10.80.0/20163.10.80.1 to 163.10.95.254163.10.95.2554,094
167163.10.96.0/20163.10.96.1 to 163.10.111.254163.10.111.2554,094
168163.10.112.0/20163.10.112.1 to 163.10.127.254163.10.127.2554,094
169163.10.128.0/20163.10.128.1 to 163.10.143.254163.10.143.2554,094
170163.10.144.0/20163.10.144.1 to 163.10.159.254163.10.159.2554,094
171163.10.160.0/20163.10.160.1 to 163.10.175.254163.10.175.2554,094
172163.10.176.0/20163.10.176.1 to 163.10.191.254163.10.191.2554,094
173163.10.192.0/20163.10.192.1 to 163.10.207.254163.10.207.2554,094
174163.10.208.0/20163.10.208.1 to 163.10.223.254163.10.223.2554,094
175163.10.224.0/20163.10.224.1 to 163.10.239.254163.10.239.2554,094
176163.10.240.0/20163.10.240.1 to 163.10.255.254163.10.255.2554,094
177163.11.0.0/20163.11.0.1 to 163.11.15.254163.11.15.2554,094
178163.11.16.0/20163.11.16.1 to 163.11.31.254163.11.31.2554,094
179163.11.32.0/20163.11.32.1 to 163.11.47.254163.11.47.2554,094
180163.11.48.0/20163.11.48.1 to 163.11.63.254163.11.63.2554,094
181163.11.64.0/20163.11.64.1 to 163.11.79.254163.11.79.2554,094
182163.11.80.0/20163.11.80.1 to 163.11.95.254163.11.95.2554,094
183163.11.96.0/20163.11.96.1 to 163.11.111.254163.11.111.2554,094
184163.11.112.0/20163.11.112.1 to 163.11.127.254163.11.127.2554,094
185163.11.128.0/20163.11.128.1 to 163.11.143.254163.11.143.2554,094
186163.11.144.0/20163.11.144.1 to 163.11.159.254163.11.159.2554,094
187163.11.160.0/20163.11.160.1 to 163.11.175.254163.11.175.2554,094
188163.11.176.0/20163.11.176.1 to 163.11.191.254163.11.191.2554,094
189163.11.192.0/20163.11.192.1 to 163.11.207.254163.11.207.2554,094
190163.11.208.0/20163.11.208.1 to 163.11.223.254163.11.223.2554,094
191163.11.224.0/20163.11.224.1 to 163.11.239.254163.11.239.2554,094
192163.11.240.0/20163.11.240.1 to 163.11.255.254163.11.255.2554,094
193163.12.0.0/20163.12.0.1 to 163.12.15.254163.12.15.2554,094
194163.12.16.0/20163.12.16.1 to 163.12.31.254163.12.31.2554,094
195163.12.32.0/20163.12.32.1 to 163.12.47.254163.12.47.2554,094
196163.12.48.0/20163.12.48.1 to 163.12.63.254163.12.63.2554,094
197163.12.64.0/20163.12.64.1 to 163.12.79.254163.12.79.2554,094
198163.12.80.0/20163.12.80.1 to 163.12.95.254163.12.95.2554,094
199163.12.96.0/20163.12.96.1 to 163.12.111.254163.12.111.2554,094
200163.12.112.0/20163.12.112.1 to 163.12.127.254163.12.127.2554,094
201163.12.128.0/20163.12.128.1 to 163.12.143.254163.12.143.2554,094
202163.12.144.0/20163.12.144.1 to 163.12.159.254163.12.159.2554,094
203163.12.160.0/20163.12.160.1 to 163.12.175.254163.12.175.2554,094
204163.12.176.0/20163.12.176.1 to 163.12.191.254163.12.191.2554,094
205163.12.192.0/20163.12.192.1 to 163.12.207.254163.12.207.2554,094
206163.12.208.0/20163.12.208.1 to 163.12.223.254163.12.223.2554,094
207163.12.224.0/20163.12.224.1 to 163.12.239.254163.12.239.2554,094
208163.12.240.0/20163.12.240.1 to 163.12.255.254163.12.255.2554,094
209163.13.0.0/20163.13.0.1 to 163.13.15.254163.13.15.2554,094
210163.13.16.0/20163.13.16.1 to 163.13.31.254163.13.31.2554,094
211163.13.32.0/20163.13.32.1 to 163.13.47.254163.13.47.2554,094
212163.13.48.0/20163.13.48.1 to 163.13.63.254163.13.63.2554,094
213163.13.64.0/20163.13.64.1 to 163.13.79.254163.13.79.2554,094
214163.13.80.0/20163.13.80.1 to 163.13.95.254163.13.95.2554,094
215163.13.96.0/20163.13.96.1 to 163.13.111.254163.13.111.2554,094
216163.13.112.0/20163.13.112.1 to 163.13.127.254163.13.127.2554,094
217163.13.128.0/20163.13.128.1 to 163.13.143.254163.13.143.2554,094
218163.13.144.0/20163.13.144.1 to 163.13.159.254163.13.159.2554,094
219163.13.160.0/20163.13.160.1 to 163.13.175.254163.13.175.2554,094
220163.13.176.0/20163.13.176.1 to 163.13.191.254163.13.191.2554,094
221163.13.192.0/20163.13.192.1 to 163.13.207.254163.13.207.2554,094
222163.13.208.0/20163.13.208.1 to 163.13.223.254163.13.223.2554,094
223163.13.224.0/20163.13.224.1 to 163.13.239.254163.13.239.2554,094
224163.13.240.0/20163.13.240.1 to 163.13.255.254163.13.255.2554,094
225163.14.0.0/20163.14.0.1 to 163.14.15.254163.14.15.2554,094
226163.14.16.0/20163.14.16.1 to 163.14.31.254163.14.31.2554,094
227163.14.32.0/20163.14.32.1 to 163.14.47.254163.14.47.2554,094
228163.14.48.0/20163.14.48.1 to 163.14.63.254163.14.63.2554,094
229163.14.64.0/20163.14.64.1 to 163.14.79.254163.14.79.2554,094
230163.14.80.0/20163.14.80.1 to 163.14.95.254163.14.95.2554,094
231163.14.96.0/20163.14.96.1 to 163.14.111.254163.14.111.2554,094
232163.14.112.0/20163.14.112.1 to 163.14.127.254163.14.127.2554,094
233163.14.128.0/20163.14.128.1 to 163.14.143.254163.14.143.2554,094
234163.14.144.0/20163.14.144.1 to 163.14.159.254163.14.159.2554,094
235163.14.160.0/20163.14.160.1 to 163.14.175.254163.14.175.2554,094
236163.14.176.0/20163.14.176.1 to 163.14.191.254163.14.191.2554,094
237163.14.192.0/20163.14.192.1 to 163.14.207.254163.14.207.2554,094
238163.14.208.0/20163.14.208.1 to 163.14.223.254163.14.223.2554,094
239163.14.224.0/20163.14.224.1 to 163.14.239.254163.14.239.2554,094
240163.14.240.0/20163.14.240.1 to 163.14.255.254163.14.255.2554,094
241163.15.0.0/20163.15.0.1 to 163.15.15.254163.15.15.2554,094
242163.15.16.0/20163.15.16.1 to 163.15.31.254163.15.31.2554,094
243163.15.32.0/20163.15.32.1 to 163.15.47.254163.15.47.2554,094
244163.15.48.0/20163.15.48.1 to 163.15.63.254163.15.63.2554,094
245163.15.64.0/20163.15.64.1 to 163.15.79.254163.15.79.2554,094
246163.15.80.0/20163.15.80.1 to 163.15.95.254163.15.95.2554,094
247163.15.96.0/20163.15.96.1 to 163.15.111.254163.15.111.2554,094
248163.15.112.0/20163.15.112.1 to 163.15.127.254163.15.127.2554,094
249163.15.128.0/20163.15.128.1 to 163.15.143.254163.15.143.2554,094
250163.15.144.0/20163.15.144.1 to 163.15.159.254163.15.159.2554,094
251163.15.160.0/20163.15.160.1 to 163.15.175.254163.15.175.2554,094
252163.15.176.0/20163.15.176.1 to 163.15.191.254163.15.191.2554,094
253163.15.192.0/20163.15.192.1 to 163.15.207.254163.15.207.2554,094
254163.15.208.0/20163.15.208.1 to 163.15.223.254163.15.223.2554,094
255163.15.224.0/20163.15.224.1 to 163.15.239.254163.15.239.2554,094
256163.15.240.0/20163.15.240.1 to 163.15.255.254163.15.255.2554,094

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.