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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.

Network165.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
165.0.0.0
Broadcast address
165.255.255.255
First usable
165.0.0.1
Last usable
165.255.255.254
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 A5000000 · Integer 2768240640 to 2785017855
Reverse DNS zone
165.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10100101..00000000.00000000.00000000165.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network10100101..00000000.00000000.00000000165.0.0.0
Broadcast10100101..11111111.11111111.11111111165.255.255.255
Split into smaller subnets/18
/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)

165.0.0.0/8 makes 1,024 subnets of /18; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1165.0.0.0/18165.0.0.1 to 165.0.63.254165.0.63.25516,382
2165.0.64.0/18165.0.64.1 to 165.0.127.254165.0.127.25516,382
3165.0.128.0/18165.0.128.1 to 165.0.191.254165.0.191.25516,382
4165.0.192.0/18165.0.192.1 to 165.0.255.254165.0.255.25516,382
5165.1.0.0/18165.1.0.1 to 165.1.63.254165.1.63.25516,382
6165.1.64.0/18165.1.64.1 to 165.1.127.254165.1.127.25516,382
7165.1.128.0/18165.1.128.1 to 165.1.191.254165.1.191.25516,382
8165.1.192.0/18165.1.192.1 to 165.1.255.254165.1.255.25516,382
9165.2.0.0/18165.2.0.1 to 165.2.63.254165.2.63.25516,382
10165.2.64.0/18165.2.64.1 to 165.2.127.254165.2.127.25516,382
11165.2.128.0/18165.2.128.1 to 165.2.191.254165.2.191.25516,382
12165.2.192.0/18165.2.192.1 to 165.2.255.254165.2.255.25516,382
13165.3.0.0/18165.3.0.1 to 165.3.63.254165.3.63.25516,382
14165.3.64.0/18165.3.64.1 to 165.3.127.254165.3.127.25516,382
15165.3.128.0/18165.3.128.1 to 165.3.191.254165.3.191.25516,382
16165.3.192.0/18165.3.192.1 to 165.3.255.254165.3.255.25516,382
17165.4.0.0/18165.4.0.1 to 165.4.63.254165.4.63.25516,382
18165.4.64.0/18165.4.64.1 to 165.4.127.254165.4.127.25516,382
19165.4.128.0/18165.4.128.1 to 165.4.191.254165.4.191.25516,382
20165.4.192.0/18165.4.192.1 to 165.4.255.254165.4.255.25516,382
21165.5.0.0/18165.5.0.1 to 165.5.63.254165.5.63.25516,382
22165.5.64.0/18165.5.64.1 to 165.5.127.254165.5.127.25516,382
23165.5.128.0/18165.5.128.1 to 165.5.191.254165.5.191.25516,382
24165.5.192.0/18165.5.192.1 to 165.5.255.254165.5.255.25516,382
25165.6.0.0/18165.6.0.1 to 165.6.63.254165.6.63.25516,382
26165.6.64.0/18165.6.64.1 to 165.6.127.254165.6.127.25516,382
27165.6.128.0/18165.6.128.1 to 165.6.191.254165.6.191.25516,382
28165.6.192.0/18165.6.192.1 to 165.6.255.254165.6.255.25516,382
29165.7.0.0/18165.7.0.1 to 165.7.63.254165.7.63.25516,382
30165.7.64.0/18165.7.64.1 to 165.7.127.254165.7.127.25516,382
31165.7.128.0/18165.7.128.1 to 165.7.191.254165.7.191.25516,382
32165.7.192.0/18165.7.192.1 to 165.7.255.254165.7.255.25516,382
33165.8.0.0/18165.8.0.1 to 165.8.63.254165.8.63.25516,382
34165.8.64.0/18165.8.64.1 to 165.8.127.254165.8.127.25516,382
35165.8.128.0/18165.8.128.1 to 165.8.191.254165.8.191.25516,382
36165.8.192.0/18165.8.192.1 to 165.8.255.254165.8.255.25516,382
37165.9.0.0/18165.9.0.1 to 165.9.63.254165.9.63.25516,382
38165.9.64.0/18165.9.64.1 to 165.9.127.254165.9.127.25516,382
39165.9.128.0/18165.9.128.1 to 165.9.191.254165.9.191.25516,382
40165.9.192.0/18165.9.192.1 to 165.9.255.254165.9.255.25516,382
41165.10.0.0/18165.10.0.1 to 165.10.63.254165.10.63.25516,382
42165.10.64.0/18165.10.64.1 to 165.10.127.254165.10.127.25516,382
43165.10.128.0/18165.10.128.1 to 165.10.191.254165.10.191.25516,382
44165.10.192.0/18165.10.192.1 to 165.10.255.254165.10.255.25516,382
45165.11.0.0/18165.11.0.1 to 165.11.63.254165.11.63.25516,382
46165.11.64.0/18165.11.64.1 to 165.11.127.254165.11.127.25516,382
47165.11.128.0/18165.11.128.1 to 165.11.191.254165.11.191.25516,382
48165.11.192.0/18165.11.192.1 to 165.11.255.254165.11.255.25516,382
49165.12.0.0/18165.12.0.1 to 165.12.63.254165.12.63.25516,382
50165.12.64.0/18165.12.64.1 to 165.12.127.254165.12.127.25516,382
51165.12.128.0/18165.12.128.1 to 165.12.191.254165.12.191.25516,382
52165.12.192.0/18165.12.192.1 to 165.12.255.254165.12.255.25516,382
53165.13.0.0/18165.13.0.1 to 165.13.63.254165.13.63.25516,382
54165.13.64.0/18165.13.64.1 to 165.13.127.254165.13.127.25516,382
55165.13.128.0/18165.13.128.1 to 165.13.191.254165.13.191.25516,382
56165.13.192.0/18165.13.192.1 to 165.13.255.254165.13.255.25516,382
57165.14.0.0/18165.14.0.1 to 165.14.63.254165.14.63.25516,382
58165.14.64.0/18165.14.64.1 to 165.14.127.254165.14.127.25516,382
59165.14.128.0/18165.14.128.1 to 165.14.191.254165.14.191.25516,382
60165.14.192.0/18165.14.192.1 to 165.14.255.254165.14.255.25516,382
61165.15.0.0/18165.15.0.1 to 165.15.63.254165.15.63.25516,382
62165.15.64.0/18165.15.64.1 to 165.15.127.254165.15.127.25516,382
63165.15.128.0/18165.15.128.1 to 165.15.191.254165.15.191.25516,382
64165.15.192.0/18165.15.192.1 to 165.15.255.254165.15.255.25516,382
65165.16.0.0/18165.16.0.1 to 165.16.63.254165.16.63.25516,382
66165.16.64.0/18165.16.64.1 to 165.16.127.254165.16.127.25516,382
67165.16.128.0/18165.16.128.1 to 165.16.191.254165.16.191.25516,382
68165.16.192.0/18165.16.192.1 to 165.16.255.254165.16.255.25516,382
69165.17.0.0/18165.17.0.1 to 165.17.63.254165.17.63.25516,382
70165.17.64.0/18165.17.64.1 to 165.17.127.254165.17.127.25516,382
71165.17.128.0/18165.17.128.1 to 165.17.191.254165.17.191.25516,382
72165.17.192.0/18165.17.192.1 to 165.17.255.254165.17.255.25516,382
73165.18.0.0/18165.18.0.1 to 165.18.63.254165.18.63.25516,382
74165.18.64.0/18165.18.64.1 to 165.18.127.254165.18.127.25516,382
75165.18.128.0/18165.18.128.1 to 165.18.191.254165.18.191.25516,382
76165.18.192.0/18165.18.192.1 to 165.18.255.254165.18.255.25516,382
77165.19.0.0/18165.19.0.1 to 165.19.63.254165.19.63.25516,382
78165.19.64.0/18165.19.64.1 to 165.19.127.254165.19.127.25516,382
79165.19.128.0/18165.19.128.1 to 165.19.191.254165.19.191.25516,382
80165.19.192.0/18165.19.192.1 to 165.19.255.254165.19.255.25516,382
81165.20.0.0/18165.20.0.1 to 165.20.63.254165.20.63.25516,382
82165.20.64.0/18165.20.64.1 to 165.20.127.254165.20.127.25516,382
83165.20.128.0/18165.20.128.1 to 165.20.191.254165.20.191.25516,382
84165.20.192.0/18165.20.192.1 to 165.20.255.254165.20.255.25516,382
85165.21.0.0/18165.21.0.1 to 165.21.63.254165.21.63.25516,382
86165.21.64.0/18165.21.64.1 to 165.21.127.254165.21.127.25516,382
87165.21.128.0/18165.21.128.1 to 165.21.191.254165.21.191.25516,382
88165.21.192.0/18165.21.192.1 to 165.21.255.254165.21.255.25516,382
89165.22.0.0/18165.22.0.1 to 165.22.63.254165.22.63.25516,382
90165.22.64.0/18165.22.64.1 to 165.22.127.254165.22.127.25516,382
91165.22.128.0/18165.22.128.1 to 165.22.191.254165.22.191.25516,382
92165.22.192.0/18165.22.192.1 to 165.22.255.254165.22.255.25516,382
93165.23.0.0/18165.23.0.1 to 165.23.63.254165.23.63.25516,382
94165.23.64.0/18165.23.64.1 to 165.23.127.254165.23.127.25516,382
95165.23.128.0/18165.23.128.1 to 165.23.191.254165.23.191.25516,382
96165.23.192.0/18165.23.192.1 to 165.23.255.254165.23.255.25516,382
97165.24.0.0/18165.24.0.1 to 165.24.63.254165.24.63.25516,382
98165.24.64.0/18165.24.64.1 to 165.24.127.254165.24.127.25516,382
99165.24.128.0/18165.24.128.1 to 165.24.191.254165.24.191.25516,382
100165.24.192.0/18165.24.192.1 to 165.24.255.254165.24.255.25516,382
101165.25.0.0/18165.25.0.1 to 165.25.63.254165.25.63.25516,382
102165.25.64.0/18165.25.64.1 to 165.25.127.254165.25.127.25516,382
103165.25.128.0/18165.25.128.1 to 165.25.191.254165.25.191.25516,382
104165.25.192.0/18165.25.192.1 to 165.25.255.254165.25.255.25516,382
105165.26.0.0/18165.26.0.1 to 165.26.63.254165.26.63.25516,382
106165.26.64.0/18165.26.64.1 to 165.26.127.254165.26.127.25516,382
107165.26.128.0/18165.26.128.1 to 165.26.191.254165.26.191.25516,382
108165.26.192.0/18165.26.192.1 to 165.26.255.254165.26.255.25516,382
109165.27.0.0/18165.27.0.1 to 165.27.63.254165.27.63.25516,382
110165.27.64.0/18165.27.64.1 to 165.27.127.254165.27.127.25516,382
111165.27.128.0/18165.27.128.1 to 165.27.191.254165.27.191.25516,382
112165.27.192.0/18165.27.192.1 to 165.27.255.254165.27.255.25516,382
113165.28.0.0/18165.28.0.1 to 165.28.63.254165.28.63.25516,382
114165.28.64.0/18165.28.64.1 to 165.28.127.254165.28.127.25516,382
115165.28.128.0/18165.28.128.1 to 165.28.191.254165.28.191.25516,382
116165.28.192.0/18165.28.192.1 to 165.28.255.254165.28.255.25516,382
117165.29.0.0/18165.29.0.1 to 165.29.63.254165.29.63.25516,382
118165.29.64.0/18165.29.64.1 to 165.29.127.254165.29.127.25516,382
119165.29.128.0/18165.29.128.1 to 165.29.191.254165.29.191.25516,382
120165.29.192.0/18165.29.192.1 to 165.29.255.254165.29.255.25516,382
121165.30.0.0/18165.30.0.1 to 165.30.63.254165.30.63.25516,382
122165.30.64.0/18165.30.64.1 to 165.30.127.254165.30.127.25516,382
123165.30.128.0/18165.30.128.1 to 165.30.191.254165.30.191.25516,382
124165.30.192.0/18165.30.192.1 to 165.30.255.254165.30.255.25516,382
125165.31.0.0/18165.31.0.1 to 165.31.63.254165.31.63.25516,382
126165.31.64.0/18165.31.64.1 to 165.31.127.254165.31.127.25516,382
127165.31.128.0/18165.31.128.1 to 165.31.191.254165.31.191.25516,382
128165.31.192.0/18165.31.192.1 to 165.31.255.254165.31.255.25516,382
129165.32.0.0/18165.32.0.1 to 165.32.63.254165.32.63.25516,382
130165.32.64.0/18165.32.64.1 to 165.32.127.254165.32.127.25516,382
131165.32.128.0/18165.32.128.1 to 165.32.191.254165.32.191.25516,382
132165.32.192.0/18165.32.192.1 to 165.32.255.254165.32.255.25516,382
133165.33.0.0/18165.33.0.1 to 165.33.63.254165.33.63.25516,382
134165.33.64.0/18165.33.64.1 to 165.33.127.254165.33.127.25516,382
135165.33.128.0/18165.33.128.1 to 165.33.191.254165.33.191.25516,382
136165.33.192.0/18165.33.192.1 to 165.33.255.254165.33.255.25516,382
137165.34.0.0/18165.34.0.1 to 165.34.63.254165.34.63.25516,382
138165.34.64.0/18165.34.64.1 to 165.34.127.254165.34.127.25516,382
139165.34.128.0/18165.34.128.1 to 165.34.191.254165.34.191.25516,382
140165.34.192.0/18165.34.192.1 to 165.34.255.254165.34.255.25516,382
141165.35.0.0/18165.35.0.1 to 165.35.63.254165.35.63.25516,382
142165.35.64.0/18165.35.64.1 to 165.35.127.254165.35.127.25516,382
143165.35.128.0/18165.35.128.1 to 165.35.191.254165.35.191.25516,382
144165.35.192.0/18165.35.192.1 to 165.35.255.254165.35.255.25516,382
145165.36.0.0/18165.36.0.1 to 165.36.63.254165.36.63.25516,382
146165.36.64.0/18165.36.64.1 to 165.36.127.254165.36.127.25516,382
147165.36.128.0/18165.36.128.1 to 165.36.191.254165.36.191.25516,382
148165.36.192.0/18165.36.192.1 to 165.36.255.254165.36.255.25516,382
149165.37.0.0/18165.37.0.1 to 165.37.63.254165.37.63.25516,382
150165.37.64.0/18165.37.64.1 to 165.37.127.254165.37.127.25516,382
151165.37.128.0/18165.37.128.1 to 165.37.191.254165.37.191.25516,382
152165.37.192.0/18165.37.192.1 to 165.37.255.254165.37.255.25516,382
153165.38.0.0/18165.38.0.1 to 165.38.63.254165.38.63.25516,382
154165.38.64.0/18165.38.64.1 to 165.38.127.254165.38.127.25516,382
155165.38.128.0/18165.38.128.1 to 165.38.191.254165.38.191.25516,382
156165.38.192.0/18165.38.192.1 to 165.38.255.254165.38.255.25516,382
157165.39.0.0/18165.39.0.1 to 165.39.63.254165.39.63.25516,382
158165.39.64.0/18165.39.64.1 to 165.39.127.254165.39.127.25516,382
159165.39.128.0/18165.39.128.1 to 165.39.191.254165.39.191.25516,382
160165.39.192.0/18165.39.192.1 to 165.39.255.254165.39.255.25516,382
161165.40.0.0/18165.40.0.1 to 165.40.63.254165.40.63.25516,382
162165.40.64.0/18165.40.64.1 to 165.40.127.254165.40.127.25516,382
163165.40.128.0/18165.40.128.1 to 165.40.191.254165.40.191.25516,382
164165.40.192.0/18165.40.192.1 to 165.40.255.254165.40.255.25516,382
165165.41.0.0/18165.41.0.1 to 165.41.63.254165.41.63.25516,382
166165.41.64.0/18165.41.64.1 to 165.41.127.254165.41.127.25516,382
167165.41.128.0/18165.41.128.1 to 165.41.191.254165.41.191.25516,382
168165.41.192.0/18165.41.192.1 to 165.41.255.254165.41.255.25516,382
169165.42.0.0/18165.42.0.1 to 165.42.63.254165.42.63.25516,382
170165.42.64.0/18165.42.64.1 to 165.42.127.254165.42.127.25516,382
171165.42.128.0/18165.42.128.1 to 165.42.191.254165.42.191.25516,382
172165.42.192.0/18165.42.192.1 to 165.42.255.254165.42.255.25516,382
173165.43.0.0/18165.43.0.1 to 165.43.63.254165.43.63.25516,382
174165.43.64.0/18165.43.64.1 to 165.43.127.254165.43.127.25516,382
175165.43.128.0/18165.43.128.1 to 165.43.191.254165.43.191.25516,382
176165.43.192.0/18165.43.192.1 to 165.43.255.254165.43.255.25516,382
177165.44.0.0/18165.44.0.1 to 165.44.63.254165.44.63.25516,382
178165.44.64.0/18165.44.64.1 to 165.44.127.254165.44.127.25516,382
179165.44.128.0/18165.44.128.1 to 165.44.191.254165.44.191.25516,382
180165.44.192.0/18165.44.192.1 to 165.44.255.254165.44.255.25516,382
181165.45.0.0/18165.45.0.1 to 165.45.63.254165.45.63.25516,382
182165.45.64.0/18165.45.64.1 to 165.45.127.254165.45.127.25516,382
183165.45.128.0/18165.45.128.1 to 165.45.191.254165.45.191.25516,382
184165.45.192.0/18165.45.192.1 to 165.45.255.254165.45.255.25516,382
185165.46.0.0/18165.46.0.1 to 165.46.63.254165.46.63.25516,382
186165.46.64.0/18165.46.64.1 to 165.46.127.254165.46.127.25516,382
187165.46.128.0/18165.46.128.1 to 165.46.191.254165.46.191.25516,382
188165.46.192.0/18165.46.192.1 to 165.46.255.254165.46.255.25516,382
189165.47.0.0/18165.47.0.1 to 165.47.63.254165.47.63.25516,382
190165.47.64.0/18165.47.64.1 to 165.47.127.254165.47.127.25516,382
191165.47.128.0/18165.47.128.1 to 165.47.191.254165.47.191.25516,382
192165.47.192.0/18165.47.192.1 to 165.47.255.254165.47.255.25516,382
193165.48.0.0/18165.48.0.1 to 165.48.63.254165.48.63.25516,382
194165.48.64.0/18165.48.64.1 to 165.48.127.254165.48.127.25516,382
195165.48.128.0/18165.48.128.1 to 165.48.191.254165.48.191.25516,382
196165.48.192.0/18165.48.192.1 to 165.48.255.254165.48.255.25516,382
197165.49.0.0/18165.49.0.1 to 165.49.63.254165.49.63.25516,382
198165.49.64.0/18165.49.64.1 to 165.49.127.254165.49.127.25516,382
199165.49.128.0/18165.49.128.1 to 165.49.191.254165.49.191.25516,382
200165.49.192.0/18165.49.192.1 to 165.49.255.254165.49.255.25516,382
201165.50.0.0/18165.50.0.1 to 165.50.63.254165.50.63.25516,382
202165.50.64.0/18165.50.64.1 to 165.50.127.254165.50.127.25516,382
203165.50.128.0/18165.50.128.1 to 165.50.191.254165.50.191.25516,382
204165.50.192.0/18165.50.192.1 to 165.50.255.254165.50.255.25516,382
205165.51.0.0/18165.51.0.1 to 165.51.63.254165.51.63.25516,382
206165.51.64.0/18165.51.64.1 to 165.51.127.254165.51.127.25516,382
207165.51.128.0/18165.51.128.1 to 165.51.191.254165.51.191.25516,382
208165.51.192.0/18165.51.192.1 to 165.51.255.254165.51.255.25516,382
209165.52.0.0/18165.52.0.1 to 165.52.63.254165.52.63.25516,382
210165.52.64.0/18165.52.64.1 to 165.52.127.254165.52.127.25516,382
211165.52.128.0/18165.52.128.1 to 165.52.191.254165.52.191.25516,382
212165.52.192.0/18165.52.192.1 to 165.52.255.254165.52.255.25516,382
213165.53.0.0/18165.53.0.1 to 165.53.63.254165.53.63.25516,382
214165.53.64.0/18165.53.64.1 to 165.53.127.254165.53.127.25516,382
215165.53.128.0/18165.53.128.1 to 165.53.191.254165.53.191.25516,382
216165.53.192.0/18165.53.192.1 to 165.53.255.254165.53.255.25516,382
217165.54.0.0/18165.54.0.1 to 165.54.63.254165.54.63.25516,382
218165.54.64.0/18165.54.64.1 to 165.54.127.254165.54.127.25516,382
219165.54.128.0/18165.54.128.1 to 165.54.191.254165.54.191.25516,382
220165.54.192.0/18165.54.192.1 to 165.54.255.254165.54.255.25516,382
221165.55.0.0/18165.55.0.1 to 165.55.63.254165.55.63.25516,382
222165.55.64.0/18165.55.64.1 to 165.55.127.254165.55.127.25516,382
223165.55.128.0/18165.55.128.1 to 165.55.191.254165.55.191.25516,382
224165.55.192.0/18165.55.192.1 to 165.55.255.254165.55.255.25516,382
225165.56.0.0/18165.56.0.1 to 165.56.63.254165.56.63.25516,382
226165.56.64.0/18165.56.64.1 to 165.56.127.254165.56.127.25516,382
227165.56.128.0/18165.56.128.1 to 165.56.191.254165.56.191.25516,382
228165.56.192.0/18165.56.192.1 to 165.56.255.254165.56.255.25516,382
229165.57.0.0/18165.57.0.1 to 165.57.63.254165.57.63.25516,382
230165.57.64.0/18165.57.64.1 to 165.57.127.254165.57.127.25516,382
231165.57.128.0/18165.57.128.1 to 165.57.191.254165.57.191.25516,382
232165.57.192.0/18165.57.192.1 to 165.57.255.254165.57.255.25516,382
233165.58.0.0/18165.58.0.1 to 165.58.63.254165.58.63.25516,382
234165.58.64.0/18165.58.64.1 to 165.58.127.254165.58.127.25516,382
235165.58.128.0/18165.58.128.1 to 165.58.191.254165.58.191.25516,382
236165.58.192.0/18165.58.192.1 to 165.58.255.254165.58.255.25516,382
237165.59.0.0/18165.59.0.1 to 165.59.63.254165.59.63.25516,382
238165.59.64.0/18165.59.64.1 to 165.59.127.254165.59.127.25516,382
239165.59.128.0/18165.59.128.1 to 165.59.191.254165.59.191.25516,382
240165.59.192.0/18165.59.192.1 to 165.59.255.254165.59.255.25516,382
241165.60.0.0/18165.60.0.1 to 165.60.63.254165.60.63.25516,382
242165.60.64.0/18165.60.64.1 to 165.60.127.254165.60.127.25516,382
243165.60.128.0/18165.60.128.1 to 165.60.191.254165.60.191.25516,382
244165.60.192.0/18165.60.192.1 to 165.60.255.254165.60.255.25516,382
245165.61.0.0/18165.61.0.1 to 165.61.63.254165.61.63.25516,382
246165.61.64.0/18165.61.64.1 to 165.61.127.254165.61.127.25516,382
247165.61.128.0/18165.61.128.1 to 165.61.191.254165.61.191.25516,382
248165.61.192.0/18165.61.192.1 to 165.61.255.254165.61.255.25516,382
249165.62.0.0/18165.62.0.1 to 165.62.63.254165.62.63.25516,382
250165.62.64.0/18165.62.64.1 to 165.62.127.254165.62.127.25516,382
251165.62.128.0/18165.62.128.1 to 165.62.191.254165.62.191.25516,382
252165.62.192.0/18165.62.192.1 to 165.62.255.254165.62.255.25516,382
253165.63.0.0/18165.63.0.1 to 165.63.63.254165.63.63.25516,382
254165.63.64.0/18165.63.64.1 to 165.63.127.254165.63.127.25516,382
255165.63.128.0/18165.63.128.1 to 165.63.191.254165.63.191.25516,382
256165.63.192.0/18165.63.192.1 to 165.63.255.254165.63.255.25516,382

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.