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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.

Network165.0.0.0/10
Usable hosts4,194,302
Subnet mask255.192.0.0
Addresses4,194,304
Network address
165.0.0.0
Broadcast address
165.63.255.255
First usable
165.0.0.1
Last usable
165.63.255.254
Usable hosts
4,194,302 (4,194,304 less the network and broadcast addresses)
Subnet mask
255.192.0.0
Wildcard mask
0.63.255.255 (Cisco ACLs, OSPF)
Prefix length
/10
Type
Public public
Old class
B (default /16)
As numbers
Hex A5000000 · Integer 2768240640 to 2772434943
Reverse DNS zones
0.165.in-addr.arpa
1.165.in-addr.arpa
2.165.in-addr.arpa
3.165.in-addr.arpa
4.165.in-addr.arpa
5.165.in-addr.arpa
6.165.in-addr.arpa
7.165.in-addr.arpa
8.165.in-addr.arpa
9.165.in-addr.arpa
10.165.in-addr.arpa
11.165.in-addr.arpa
12.165.in-addr.arpa
13.165.in-addr.arpa
14.165.in-addr.arpa
15.165.in-addr.arpa
and 48 more
/10 is not on a 8-bit boundary, so it takes 64 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10100101.00000000.00000000.00000000165.0.0.0
Subnet mask11111111.11000000.00000000.00000000255.192.0.0
Network10100101.00000000.00000000.00000000165.0.0.0
Broadcast10100101.00111111.11111111.11111111165.63.255.255
Split into smaller subnets/19
/11 (2)/12 (4)/13 (8)/14 (16)/15 (32)/16 (64)/17 (128)/18 (256)/19 (512)/20 (1,024)/21 (2,048)/22 (4,096)

165.0.0.0/10 makes 512 subnets of /19; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1165.0.0.0/19165.0.0.1 to 165.0.31.254165.0.31.2558,190
2165.0.32.0/19165.0.32.1 to 165.0.63.254165.0.63.2558,190
3165.0.64.0/19165.0.64.1 to 165.0.95.254165.0.95.2558,190
4165.0.96.0/19165.0.96.1 to 165.0.127.254165.0.127.2558,190
5165.0.128.0/19165.0.128.1 to 165.0.159.254165.0.159.2558,190
6165.0.160.0/19165.0.160.1 to 165.0.191.254165.0.191.2558,190
7165.0.192.0/19165.0.192.1 to 165.0.223.254165.0.223.2558,190
8165.0.224.0/19165.0.224.1 to 165.0.255.254165.0.255.2558,190
9165.1.0.0/19165.1.0.1 to 165.1.31.254165.1.31.2558,190
10165.1.32.0/19165.1.32.1 to 165.1.63.254165.1.63.2558,190
11165.1.64.0/19165.1.64.1 to 165.1.95.254165.1.95.2558,190
12165.1.96.0/19165.1.96.1 to 165.1.127.254165.1.127.2558,190
13165.1.128.0/19165.1.128.1 to 165.1.159.254165.1.159.2558,190
14165.1.160.0/19165.1.160.1 to 165.1.191.254165.1.191.2558,190
15165.1.192.0/19165.1.192.1 to 165.1.223.254165.1.223.2558,190
16165.1.224.0/19165.1.224.1 to 165.1.255.254165.1.255.2558,190
17165.2.0.0/19165.2.0.1 to 165.2.31.254165.2.31.2558,190
18165.2.32.0/19165.2.32.1 to 165.2.63.254165.2.63.2558,190
19165.2.64.0/19165.2.64.1 to 165.2.95.254165.2.95.2558,190
20165.2.96.0/19165.2.96.1 to 165.2.127.254165.2.127.2558,190
21165.2.128.0/19165.2.128.1 to 165.2.159.254165.2.159.2558,190
22165.2.160.0/19165.2.160.1 to 165.2.191.254165.2.191.2558,190
23165.2.192.0/19165.2.192.1 to 165.2.223.254165.2.223.2558,190
24165.2.224.0/19165.2.224.1 to 165.2.255.254165.2.255.2558,190
25165.3.0.0/19165.3.0.1 to 165.3.31.254165.3.31.2558,190
26165.3.32.0/19165.3.32.1 to 165.3.63.254165.3.63.2558,190
27165.3.64.0/19165.3.64.1 to 165.3.95.254165.3.95.2558,190
28165.3.96.0/19165.3.96.1 to 165.3.127.254165.3.127.2558,190
29165.3.128.0/19165.3.128.1 to 165.3.159.254165.3.159.2558,190
30165.3.160.0/19165.3.160.1 to 165.3.191.254165.3.191.2558,190
31165.3.192.0/19165.3.192.1 to 165.3.223.254165.3.223.2558,190
32165.3.224.0/19165.3.224.1 to 165.3.255.254165.3.255.2558,190
33165.4.0.0/19165.4.0.1 to 165.4.31.254165.4.31.2558,190
34165.4.32.0/19165.4.32.1 to 165.4.63.254165.4.63.2558,190
35165.4.64.0/19165.4.64.1 to 165.4.95.254165.4.95.2558,190
36165.4.96.0/19165.4.96.1 to 165.4.127.254165.4.127.2558,190
37165.4.128.0/19165.4.128.1 to 165.4.159.254165.4.159.2558,190
38165.4.160.0/19165.4.160.1 to 165.4.191.254165.4.191.2558,190
39165.4.192.0/19165.4.192.1 to 165.4.223.254165.4.223.2558,190
40165.4.224.0/19165.4.224.1 to 165.4.255.254165.4.255.2558,190
41165.5.0.0/19165.5.0.1 to 165.5.31.254165.5.31.2558,190
42165.5.32.0/19165.5.32.1 to 165.5.63.254165.5.63.2558,190
43165.5.64.0/19165.5.64.1 to 165.5.95.254165.5.95.2558,190
44165.5.96.0/19165.5.96.1 to 165.5.127.254165.5.127.2558,190
45165.5.128.0/19165.5.128.1 to 165.5.159.254165.5.159.2558,190
46165.5.160.0/19165.5.160.1 to 165.5.191.254165.5.191.2558,190
47165.5.192.0/19165.5.192.1 to 165.5.223.254165.5.223.2558,190
48165.5.224.0/19165.5.224.1 to 165.5.255.254165.5.255.2558,190
49165.6.0.0/19165.6.0.1 to 165.6.31.254165.6.31.2558,190
50165.6.32.0/19165.6.32.1 to 165.6.63.254165.6.63.2558,190
51165.6.64.0/19165.6.64.1 to 165.6.95.254165.6.95.2558,190
52165.6.96.0/19165.6.96.1 to 165.6.127.254165.6.127.2558,190
53165.6.128.0/19165.6.128.1 to 165.6.159.254165.6.159.2558,190
54165.6.160.0/19165.6.160.1 to 165.6.191.254165.6.191.2558,190
55165.6.192.0/19165.6.192.1 to 165.6.223.254165.6.223.2558,190
56165.6.224.0/19165.6.224.1 to 165.6.255.254165.6.255.2558,190
57165.7.0.0/19165.7.0.1 to 165.7.31.254165.7.31.2558,190
58165.7.32.0/19165.7.32.1 to 165.7.63.254165.7.63.2558,190
59165.7.64.0/19165.7.64.1 to 165.7.95.254165.7.95.2558,190
60165.7.96.0/19165.7.96.1 to 165.7.127.254165.7.127.2558,190
61165.7.128.0/19165.7.128.1 to 165.7.159.254165.7.159.2558,190
62165.7.160.0/19165.7.160.1 to 165.7.191.254165.7.191.2558,190
63165.7.192.0/19165.7.192.1 to 165.7.223.254165.7.223.2558,190
64165.7.224.0/19165.7.224.1 to 165.7.255.254165.7.255.2558,190
65165.8.0.0/19165.8.0.1 to 165.8.31.254165.8.31.2558,190
66165.8.32.0/19165.8.32.1 to 165.8.63.254165.8.63.2558,190
67165.8.64.0/19165.8.64.1 to 165.8.95.254165.8.95.2558,190
68165.8.96.0/19165.8.96.1 to 165.8.127.254165.8.127.2558,190
69165.8.128.0/19165.8.128.1 to 165.8.159.254165.8.159.2558,190
70165.8.160.0/19165.8.160.1 to 165.8.191.254165.8.191.2558,190
71165.8.192.0/19165.8.192.1 to 165.8.223.254165.8.223.2558,190
72165.8.224.0/19165.8.224.1 to 165.8.255.254165.8.255.2558,190
73165.9.0.0/19165.9.0.1 to 165.9.31.254165.9.31.2558,190
74165.9.32.0/19165.9.32.1 to 165.9.63.254165.9.63.2558,190
75165.9.64.0/19165.9.64.1 to 165.9.95.254165.9.95.2558,190
76165.9.96.0/19165.9.96.1 to 165.9.127.254165.9.127.2558,190
77165.9.128.0/19165.9.128.1 to 165.9.159.254165.9.159.2558,190
78165.9.160.0/19165.9.160.1 to 165.9.191.254165.9.191.2558,190
79165.9.192.0/19165.9.192.1 to 165.9.223.254165.9.223.2558,190
80165.9.224.0/19165.9.224.1 to 165.9.255.254165.9.255.2558,190
81165.10.0.0/19165.10.0.1 to 165.10.31.254165.10.31.2558,190
82165.10.32.0/19165.10.32.1 to 165.10.63.254165.10.63.2558,190
83165.10.64.0/19165.10.64.1 to 165.10.95.254165.10.95.2558,190
84165.10.96.0/19165.10.96.1 to 165.10.127.254165.10.127.2558,190
85165.10.128.0/19165.10.128.1 to 165.10.159.254165.10.159.2558,190
86165.10.160.0/19165.10.160.1 to 165.10.191.254165.10.191.2558,190
87165.10.192.0/19165.10.192.1 to 165.10.223.254165.10.223.2558,190
88165.10.224.0/19165.10.224.1 to 165.10.255.254165.10.255.2558,190
89165.11.0.0/19165.11.0.1 to 165.11.31.254165.11.31.2558,190
90165.11.32.0/19165.11.32.1 to 165.11.63.254165.11.63.2558,190
91165.11.64.0/19165.11.64.1 to 165.11.95.254165.11.95.2558,190
92165.11.96.0/19165.11.96.1 to 165.11.127.254165.11.127.2558,190
93165.11.128.0/19165.11.128.1 to 165.11.159.254165.11.159.2558,190
94165.11.160.0/19165.11.160.1 to 165.11.191.254165.11.191.2558,190
95165.11.192.0/19165.11.192.1 to 165.11.223.254165.11.223.2558,190
96165.11.224.0/19165.11.224.1 to 165.11.255.254165.11.255.2558,190
97165.12.0.0/19165.12.0.1 to 165.12.31.254165.12.31.2558,190
98165.12.32.0/19165.12.32.1 to 165.12.63.254165.12.63.2558,190
99165.12.64.0/19165.12.64.1 to 165.12.95.254165.12.95.2558,190
100165.12.96.0/19165.12.96.1 to 165.12.127.254165.12.127.2558,190
101165.12.128.0/19165.12.128.1 to 165.12.159.254165.12.159.2558,190
102165.12.160.0/19165.12.160.1 to 165.12.191.254165.12.191.2558,190
103165.12.192.0/19165.12.192.1 to 165.12.223.254165.12.223.2558,190
104165.12.224.0/19165.12.224.1 to 165.12.255.254165.12.255.2558,190
105165.13.0.0/19165.13.0.1 to 165.13.31.254165.13.31.2558,190
106165.13.32.0/19165.13.32.1 to 165.13.63.254165.13.63.2558,190
107165.13.64.0/19165.13.64.1 to 165.13.95.254165.13.95.2558,190
108165.13.96.0/19165.13.96.1 to 165.13.127.254165.13.127.2558,190
109165.13.128.0/19165.13.128.1 to 165.13.159.254165.13.159.2558,190
110165.13.160.0/19165.13.160.1 to 165.13.191.254165.13.191.2558,190
111165.13.192.0/19165.13.192.1 to 165.13.223.254165.13.223.2558,190
112165.13.224.0/19165.13.224.1 to 165.13.255.254165.13.255.2558,190
113165.14.0.0/19165.14.0.1 to 165.14.31.254165.14.31.2558,190
114165.14.32.0/19165.14.32.1 to 165.14.63.254165.14.63.2558,190
115165.14.64.0/19165.14.64.1 to 165.14.95.254165.14.95.2558,190
116165.14.96.0/19165.14.96.1 to 165.14.127.254165.14.127.2558,190
117165.14.128.0/19165.14.128.1 to 165.14.159.254165.14.159.2558,190
118165.14.160.0/19165.14.160.1 to 165.14.191.254165.14.191.2558,190
119165.14.192.0/19165.14.192.1 to 165.14.223.254165.14.223.2558,190
120165.14.224.0/19165.14.224.1 to 165.14.255.254165.14.255.2558,190
121165.15.0.0/19165.15.0.1 to 165.15.31.254165.15.31.2558,190
122165.15.32.0/19165.15.32.1 to 165.15.63.254165.15.63.2558,190
123165.15.64.0/19165.15.64.1 to 165.15.95.254165.15.95.2558,190
124165.15.96.0/19165.15.96.1 to 165.15.127.254165.15.127.2558,190
125165.15.128.0/19165.15.128.1 to 165.15.159.254165.15.159.2558,190
126165.15.160.0/19165.15.160.1 to 165.15.191.254165.15.191.2558,190
127165.15.192.0/19165.15.192.1 to 165.15.223.254165.15.223.2558,190
128165.15.224.0/19165.15.224.1 to 165.15.255.254165.15.255.2558,190
129165.16.0.0/19165.16.0.1 to 165.16.31.254165.16.31.2558,190
130165.16.32.0/19165.16.32.1 to 165.16.63.254165.16.63.2558,190
131165.16.64.0/19165.16.64.1 to 165.16.95.254165.16.95.2558,190
132165.16.96.0/19165.16.96.1 to 165.16.127.254165.16.127.2558,190
133165.16.128.0/19165.16.128.1 to 165.16.159.254165.16.159.2558,190
134165.16.160.0/19165.16.160.1 to 165.16.191.254165.16.191.2558,190
135165.16.192.0/19165.16.192.1 to 165.16.223.254165.16.223.2558,190
136165.16.224.0/19165.16.224.1 to 165.16.255.254165.16.255.2558,190
137165.17.0.0/19165.17.0.1 to 165.17.31.254165.17.31.2558,190
138165.17.32.0/19165.17.32.1 to 165.17.63.254165.17.63.2558,190
139165.17.64.0/19165.17.64.1 to 165.17.95.254165.17.95.2558,190
140165.17.96.0/19165.17.96.1 to 165.17.127.254165.17.127.2558,190
141165.17.128.0/19165.17.128.1 to 165.17.159.254165.17.159.2558,190
142165.17.160.0/19165.17.160.1 to 165.17.191.254165.17.191.2558,190
143165.17.192.0/19165.17.192.1 to 165.17.223.254165.17.223.2558,190
144165.17.224.0/19165.17.224.1 to 165.17.255.254165.17.255.2558,190
145165.18.0.0/19165.18.0.1 to 165.18.31.254165.18.31.2558,190
146165.18.32.0/19165.18.32.1 to 165.18.63.254165.18.63.2558,190
147165.18.64.0/19165.18.64.1 to 165.18.95.254165.18.95.2558,190
148165.18.96.0/19165.18.96.1 to 165.18.127.254165.18.127.2558,190
149165.18.128.0/19165.18.128.1 to 165.18.159.254165.18.159.2558,190
150165.18.160.0/19165.18.160.1 to 165.18.191.254165.18.191.2558,190
151165.18.192.0/19165.18.192.1 to 165.18.223.254165.18.223.2558,190
152165.18.224.0/19165.18.224.1 to 165.18.255.254165.18.255.2558,190
153165.19.0.0/19165.19.0.1 to 165.19.31.254165.19.31.2558,190
154165.19.32.0/19165.19.32.1 to 165.19.63.254165.19.63.2558,190
155165.19.64.0/19165.19.64.1 to 165.19.95.254165.19.95.2558,190
156165.19.96.0/19165.19.96.1 to 165.19.127.254165.19.127.2558,190
157165.19.128.0/19165.19.128.1 to 165.19.159.254165.19.159.2558,190
158165.19.160.0/19165.19.160.1 to 165.19.191.254165.19.191.2558,190
159165.19.192.0/19165.19.192.1 to 165.19.223.254165.19.223.2558,190
160165.19.224.0/19165.19.224.1 to 165.19.255.254165.19.255.2558,190
161165.20.0.0/19165.20.0.1 to 165.20.31.254165.20.31.2558,190
162165.20.32.0/19165.20.32.1 to 165.20.63.254165.20.63.2558,190
163165.20.64.0/19165.20.64.1 to 165.20.95.254165.20.95.2558,190
164165.20.96.0/19165.20.96.1 to 165.20.127.254165.20.127.2558,190
165165.20.128.0/19165.20.128.1 to 165.20.159.254165.20.159.2558,190
166165.20.160.0/19165.20.160.1 to 165.20.191.254165.20.191.2558,190
167165.20.192.0/19165.20.192.1 to 165.20.223.254165.20.223.2558,190
168165.20.224.0/19165.20.224.1 to 165.20.255.254165.20.255.2558,190
169165.21.0.0/19165.21.0.1 to 165.21.31.254165.21.31.2558,190
170165.21.32.0/19165.21.32.1 to 165.21.63.254165.21.63.2558,190
171165.21.64.0/19165.21.64.1 to 165.21.95.254165.21.95.2558,190
172165.21.96.0/19165.21.96.1 to 165.21.127.254165.21.127.2558,190
173165.21.128.0/19165.21.128.1 to 165.21.159.254165.21.159.2558,190
174165.21.160.0/19165.21.160.1 to 165.21.191.254165.21.191.2558,190
175165.21.192.0/19165.21.192.1 to 165.21.223.254165.21.223.2558,190
176165.21.224.0/19165.21.224.1 to 165.21.255.254165.21.255.2558,190
177165.22.0.0/19165.22.0.1 to 165.22.31.254165.22.31.2558,190
178165.22.32.0/19165.22.32.1 to 165.22.63.254165.22.63.2558,190
179165.22.64.0/19165.22.64.1 to 165.22.95.254165.22.95.2558,190
180165.22.96.0/19165.22.96.1 to 165.22.127.254165.22.127.2558,190
181165.22.128.0/19165.22.128.1 to 165.22.159.254165.22.159.2558,190
182165.22.160.0/19165.22.160.1 to 165.22.191.254165.22.191.2558,190
183165.22.192.0/19165.22.192.1 to 165.22.223.254165.22.223.2558,190
184165.22.224.0/19165.22.224.1 to 165.22.255.254165.22.255.2558,190
185165.23.0.0/19165.23.0.1 to 165.23.31.254165.23.31.2558,190
186165.23.32.0/19165.23.32.1 to 165.23.63.254165.23.63.2558,190
187165.23.64.0/19165.23.64.1 to 165.23.95.254165.23.95.2558,190
188165.23.96.0/19165.23.96.1 to 165.23.127.254165.23.127.2558,190
189165.23.128.0/19165.23.128.1 to 165.23.159.254165.23.159.2558,190
190165.23.160.0/19165.23.160.1 to 165.23.191.254165.23.191.2558,190
191165.23.192.0/19165.23.192.1 to 165.23.223.254165.23.223.2558,190
192165.23.224.0/19165.23.224.1 to 165.23.255.254165.23.255.2558,190
193165.24.0.0/19165.24.0.1 to 165.24.31.254165.24.31.2558,190
194165.24.32.0/19165.24.32.1 to 165.24.63.254165.24.63.2558,190
195165.24.64.0/19165.24.64.1 to 165.24.95.254165.24.95.2558,190
196165.24.96.0/19165.24.96.1 to 165.24.127.254165.24.127.2558,190
197165.24.128.0/19165.24.128.1 to 165.24.159.254165.24.159.2558,190
198165.24.160.0/19165.24.160.1 to 165.24.191.254165.24.191.2558,190
199165.24.192.0/19165.24.192.1 to 165.24.223.254165.24.223.2558,190
200165.24.224.0/19165.24.224.1 to 165.24.255.254165.24.255.2558,190
201165.25.0.0/19165.25.0.1 to 165.25.31.254165.25.31.2558,190
202165.25.32.0/19165.25.32.1 to 165.25.63.254165.25.63.2558,190
203165.25.64.0/19165.25.64.1 to 165.25.95.254165.25.95.2558,190
204165.25.96.0/19165.25.96.1 to 165.25.127.254165.25.127.2558,190
205165.25.128.0/19165.25.128.1 to 165.25.159.254165.25.159.2558,190
206165.25.160.0/19165.25.160.1 to 165.25.191.254165.25.191.2558,190
207165.25.192.0/19165.25.192.1 to 165.25.223.254165.25.223.2558,190
208165.25.224.0/19165.25.224.1 to 165.25.255.254165.25.255.2558,190
209165.26.0.0/19165.26.0.1 to 165.26.31.254165.26.31.2558,190
210165.26.32.0/19165.26.32.1 to 165.26.63.254165.26.63.2558,190
211165.26.64.0/19165.26.64.1 to 165.26.95.254165.26.95.2558,190
212165.26.96.0/19165.26.96.1 to 165.26.127.254165.26.127.2558,190
213165.26.128.0/19165.26.128.1 to 165.26.159.254165.26.159.2558,190
214165.26.160.0/19165.26.160.1 to 165.26.191.254165.26.191.2558,190
215165.26.192.0/19165.26.192.1 to 165.26.223.254165.26.223.2558,190
216165.26.224.0/19165.26.224.1 to 165.26.255.254165.26.255.2558,190
217165.27.0.0/19165.27.0.1 to 165.27.31.254165.27.31.2558,190
218165.27.32.0/19165.27.32.1 to 165.27.63.254165.27.63.2558,190
219165.27.64.0/19165.27.64.1 to 165.27.95.254165.27.95.2558,190
220165.27.96.0/19165.27.96.1 to 165.27.127.254165.27.127.2558,190
221165.27.128.0/19165.27.128.1 to 165.27.159.254165.27.159.2558,190
222165.27.160.0/19165.27.160.1 to 165.27.191.254165.27.191.2558,190
223165.27.192.0/19165.27.192.1 to 165.27.223.254165.27.223.2558,190
224165.27.224.0/19165.27.224.1 to 165.27.255.254165.27.255.2558,190
225165.28.0.0/19165.28.0.1 to 165.28.31.254165.28.31.2558,190
226165.28.32.0/19165.28.32.1 to 165.28.63.254165.28.63.2558,190
227165.28.64.0/19165.28.64.1 to 165.28.95.254165.28.95.2558,190
228165.28.96.0/19165.28.96.1 to 165.28.127.254165.28.127.2558,190
229165.28.128.0/19165.28.128.1 to 165.28.159.254165.28.159.2558,190
230165.28.160.0/19165.28.160.1 to 165.28.191.254165.28.191.2558,190
231165.28.192.0/19165.28.192.1 to 165.28.223.254165.28.223.2558,190
232165.28.224.0/19165.28.224.1 to 165.28.255.254165.28.255.2558,190
233165.29.0.0/19165.29.0.1 to 165.29.31.254165.29.31.2558,190
234165.29.32.0/19165.29.32.1 to 165.29.63.254165.29.63.2558,190
235165.29.64.0/19165.29.64.1 to 165.29.95.254165.29.95.2558,190
236165.29.96.0/19165.29.96.1 to 165.29.127.254165.29.127.2558,190
237165.29.128.0/19165.29.128.1 to 165.29.159.254165.29.159.2558,190
238165.29.160.0/19165.29.160.1 to 165.29.191.254165.29.191.2558,190
239165.29.192.0/19165.29.192.1 to 165.29.223.254165.29.223.2558,190
240165.29.224.0/19165.29.224.1 to 165.29.255.254165.29.255.2558,190
241165.30.0.0/19165.30.0.1 to 165.30.31.254165.30.31.2558,190
242165.30.32.0/19165.30.32.1 to 165.30.63.254165.30.63.2558,190
243165.30.64.0/19165.30.64.1 to 165.30.95.254165.30.95.2558,190
244165.30.96.0/19165.30.96.1 to 165.30.127.254165.30.127.2558,190
245165.30.128.0/19165.30.128.1 to 165.30.159.254165.30.159.2558,190
246165.30.160.0/19165.30.160.1 to 165.30.191.254165.30.191.2558,190
247165.30.192.0/19165.30.192.1 to 165.30.223.254165.30.223.2558,190
248165.30.224.0/19165.30.224.1 to 165.30.255.254165.30.255.2558,190
249165.31.0.0/19165.31.0.1 to 165.31.31.254165.31.31.2558,190
250165.31.32.0/19165.31.32.1 to 165.31.63.254165.31.63.2558,190
251165.31.64.0/19165.31.64.1 to 165.31.95.254165.31.95.2558,190
252165.31.96.0/19165.31.96.1 to 165.31.127.254165.31.127.2558,190
253165.31.128.0/19165.31.128.1 to 165.31.159.254165.31.159.2558,190
254165.31.160.0/19165.31.160.1 to 165.31.191.254165.31.191.2558,190
255165.31.192.0/19165.31.192.1 to 165.31.223.254165.31.223.2558,190
256165.31.224.0/19165.31.224.1 to 165.31.255.254165.31.255.2558,190

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.