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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/17
/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 512 subnets of /17; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1165.0.0.0/17165.0.0.1 to 165.0.127.254165.0.127.25532,766
2165.0.128.0/17165.0.128.1 to 165.0.255.254165.0.255.25532,766
3165.1.0.0/17165.1.0.1 to 165.1.127.254165.1.127.25532,766
4165.1.128.0/17165.1.128.1 to 165.1.255.254165.1.255.25532,766
5165.2.0.0/17165.2.0.1 to 165.2.127.254165.2.127.25532,766
6165.2.128.0/17165.2.128.1 to 165.2.255.254165.2.255.25532,766
7165.3.0.0/17165.3.0.1 to 165.3.127.254165.3.127.25532,766
8165.3.128.0/17165.3.128.1 to 165.3.255.254165.3.255.25532,766
9165.4.0.0/17165.4.0.1 to 165.4.127.254165.4.127.25532,766
10165.4.128.0/17165.4.128.1 to 165.4.255.254165.4.255.25532,766
11165.5.0.0/17165.5.0.1 to 165.5.127.254165.5.127.25532,766
12165.5.128.0/17165.5.128.1 to 165.5.255.254165.5.255.25532,766
13165.6.0.0/17165.6.0.1 to 165.6.127.254165.6.127.25532,766
14165.6.128.0/17165.6.128.1 to 165.6.255.254165.6.255.25532,766
15165.7.0.0/17165.7.0.1 to 165.7.127.254165.7.127.25532,766
16165.7.128.0/17165.7.128.1 to 165.7.255.254165.7.255.25532,766
17165.8.0.0/17165.8.0.1 to 165.8.127.254165.8.127.25532,766
18165.8.128.0/17165.8.128.1 to 165.8.255.254165.8.255.25532,766
19165.9.0.0/17165.9.0.1 to 165.9.127.254165.9.127.25532,766
20165.9.128.0/17165.9.128.1 to 165.9.255.254165.9.255.25532,766
21165.10.0.0/17165.10.0.1 to 165.10.127.254165.10.127.25532,766
22165.10.128.0/17165.10.128.1 to 165.10.255.254165.10.255.25532,766
23165.11.0.0/17165.11.0.1 to 165.11.127.254165.11.127.25532,766
24165.11.128.0/17165.11.128.1 to 165.11.255.254165.11.255.25532,766
25165.12.0.0/17165.12.0.1 to 165.12.127.254165.12.127.25532,766
26165.12.128.0/17165.12.128.1 to 165.12.255.254165.12.255.25532,766
27165.13.0.0/17165.13.0.1 to 165.13.127.254165.13.127.25532,766
28165.13.128.0/17165.13.128.1 to 165.13.255.254165.13.255.25532,766
29165.14.0.0/17165.14.0.1 to 165.14.127.254165.14.127.25532,766
30165.14.128.0/17165.14.128.1 to 165.14.255.254165.14.255.25532,766
31165.15.0.0/17165.15.0.1 to 165.15.127.254165.15.127.25532,766
32165.15.128.0/17165.15.128.1 to 165.15.255.254165.15.255.25532,766
33165.16.0.0/17165.16.0.1 to 165.16.127.254165.16.127.25532,766
34165.16.128.0/17165.16.128.1 to 165.16.255.254165.16.255.25532,766
35165.17.0.0/17165.17.0.1 to 165.17.127.254165.17.127.25532,766
36165.17.128.0/17165.17.128.1 to 165.17.255.254165.17.255.25532,766
37165.18.0.0/17165.18.0.1 to 165.18.127.254165.18.127.25532,766
38165.18.128.0/17165.18.128.1 to 165.18.255.254165.18.255.25532,766
39165.19.0.0/17165.19.0.1 to 165.19.127.254165.19.127.25532,766
40165.19.128.0/17165.19.128.1 to 165.19.255.254165.19.255.25532,766
41165.20.0.0/17165.20.0.1 to 165.20.127.254165.20.127.25532,766
42165.20.128.0/17165.20.128.1 to 165.20.255.254165.20.255.25532,766
43165.21.0.0/17165.21.0.1 to 165.21.127.254165.21.127.25532,766
44165.21.128.0/17165.21.128.1 to 165.21.255.254165.21.255.25532,766
45165.22.0.0/17165.22.0.1 to 165.22.127.254165.22.127.25532,766
46165.22.128.0/17165.22.128.1 to 165.22.255.254165.22.255.25532,766
47165.23.0.0/17165.23.0.1 to 165.23.127.254165.23.127.25532,766
48165.23.128.0/17165.23.128.1 to 165.23.255.254165.23.255.25532,766
49165.24.0.0/17165.24.0.1 to 165.24.127.254165.24.127.25532,766
50165.24.128.0/17165.24.128.1 to 165.24.255.254165.24.255.25532,766
51165.25.0.0/17165.25.0.1 to 165.25.127.254165.25.127.25532,766
52165.25.128.0/17165.25.128.1 to 165.25.255.254165.25.255.25532,766
53165.26.0.0/17165.26.0.1 to 165.26.127.254165.26.127.25532,766
54165.26.128.0/17165.26.128.1 to 165.26.255.254165.26.255.25532,766
55165.27.0.0/17165.27.0.1 to 165.27.127.254165.27.127.25532,766
56165.27.128.0/17165.27.128.1 to 165.27.255.254165.27.255.25532,766
57165.28.0.0/17165.28.0.1 to 165.28.127.254165.28.127.25532,766
58165.28.128.0/17165.28.128.1 to 165.28.255.254165.28.255.25532,766
59165.29.0.0/17165.29.0.1 to 165.29.127.254165.29.127.25532,766
60165.29.128.0/17165.29.128.1 to 165.29.255.254165.29.255.25532,766
61165.30.0.0/17165.30.0.1 to 165.30.127.254165.30.127.25532,766
62165.30.128.0/17165.30.128.1 to 165.30.255.254165.30.255.25532,766
63165.31.0.0/17165.31.0.1 to 165.31.127.254165.31.127.25532,766
64165.31.128.0/17165.31.128.1 to 165.31.255.254165.31.255.25532,766
65165.32.0.0/17165.32.0.1 to 165.32.127.254165.32.127.25532,766
66165.32.128.0/17165.32.128.1 to 165.32.255.254165.32.255.25532,766
67165.33.0.0/17165.33.0.1 to 165.33.127.254165.33.127.25532,766
68165.33.128.0/17165.33.128.1 to 165.33.255.254165.33.255.25532,766
69165.34.0.0/17165.34.0.1 to 165.34.127.254165.34.127.25532,766
70165.34.128.0/17165.34.128.1 to 165.34.255.254165.34.255.25532,766
71165.35.0.0/17165.35.0.1 to 165.35.127.254165.35.127.25532,766
72165.35.128.0/17165.35.128.1 to 165.35.255.254165.35.255.25532,766
73165.36.0.0/17165.36.0.1 to 165.36.127.254165.36.127.25532,766
74165.36.128.0/17165.36.128.1 to 165.36.255.254165.36.255.25532,766
75165.37.0.0/17165.37.0.1 to 165.37.127.254165.37.127.25532,766
76165.37.128.0/17165.37.128.1 to 165.37.255.254165.37.255.25532,766
77165.38.0.0/17165.38.0.1 to 165.38.127.254165.38.127.25532,766
78165.38.128.0/17165.38.128.1 to 165.38.255.254165.38.255.25532,766
79165.39.0.0/17165.39.0.1 to 165.39.127.254165.39.127.25532,766
80165.39.128.0/17165.39.128.1 to 165.39.255.254165.39.255.25532,766
81165.40.0.0/17165.40.0.1 to 165.40.127.254165.40.127.25532,766
82165.40.128.0/17165.40.128.1 to 165.40.255.254165.40.255.25532,766
83165.41.0.0/17165.41.0.1 to 165.41.127.254165.41.127.25532,766
84165.41.128.0/17165.41.128.1 to 165.41.255.254165.41.255.25532,766
85165.42.0.0/17165.42.0.1 to 165.42.127.254165.42.127.25532,766
86165.42.128.0/17165.42.128.1 to 165.42.255.254165.42.255.25532,766
87165.43.0.0/17165.43.0.1 to 165.43.127.254165.43.127.25532,766
88165.43.128.0/17165.43.128.1 to 165.43.255.254165.43.255.25532,766
89165.44.0.0/17165.44.0.1 to 165.44.127.254165.44.127.25532,766
90165.44.128.0/17165.44.128.1 to 165.44.255.254165.44.255.25532,766
91165.45.0.0/17165.45.0.1 to 165.45.127.254165.45.127.25532,766
92165.45.128.0/17165.45.128.1 to 165.45.255.254165.45.255.25532,766
93165.46.0.0/17165.46.0.1 to 165.46.127.254165.46.127.25532,766
94165.46.128.0/17165.46.128.1 to 165.46.255.254165.46.255.25532,766
95165.47.0.0/17165.47.0.1 to 165.47.127.254165.47.127.25532,766
96165.47.128.0/17165.47.128.1 to 165.47.255.254165.47.255.25532,766
97165.48.0.0/17165.48.0.1 to 165.48.127.254165.48.127.25532,766
98165.48.128.0/17165.48.128.1 to 165.48.255.254165.48.255.25532,766
99165.49.0.0/17165.49.0.1 to 165.49.127.254165.49.127.25532,766
100165.49.128.0/17165.49.128.1 to 165.49.255.254165.49.255.25532,766
101165.50.0.0/17165.50.0.1 to 165.50.127.254165.50.127.25532,766
102165.50.128.0/17165.50.128.1 to 165.50.255.254165.50.255.25532,766
103165.51.0.0/17165.51.0.1 to 165.51.127.254165.51.127.25532,766
104165.51.128.0/17165.51.128.1 to 165.51.255.254165.51.255.25532,766
105165.52.0.0/17165.52.0.1 to 165.52.127.254165.52.127.25532,766
106165.52.128.0/17165.52.128.1 to 165.52.255.254165.52.255.25532,766
107165.53.0.0/17165.53.0.1 to 165.53.127.254165.53.127.25532,766
108165.53.128.0/17165.53.128.1 to 165.53.255.254165.53.255.25532,766
109165.54.0.0/17165.54.0.1 to 165.54.127.254165.54.127.25532,766
110165.54.128.0/17165.54.128.1 to 165.54.255.254165.54.255.25532,766
111165.55.0.0/17165.55.0.1 to 165.55.127.254165.55.127.25532,766
112165.55.128.0/17165.55.128.1 to 165.55.255.254165.55.255.25532,766
113165.56.0.0/17165.56.0.1 to 165.56.127.254165.56.127.25532,766
114165.56.128.0/17165.56.128.1 to 165.56.255.254165.56.255.25532,766
115165.57.0.0/17165.57.0.1 to 165.57.127.254165.57.127.25532,766
116165.57.128.0/17165.57.128.1 to 165.57.255.254165.57.255.25532,766
117165.58.0.0/17165.58.0.1 to 165.58.127.254165.58.127.25532,766
118165.58.128.0/17165.58.128.1 to 165.58.255.254165.58.255.25532,766
119165.59.0.0/17165.59.0.1 to 165.59.127.254165.59.127.25532,766
120165.59.128.0/17165.59.128.1 to 165.59.255.254165.59.255.25532,766
121165.60.0.0/17165.60.0.1 to 165.60.127.254165.60.127.25532,766
122165.60.128.0/17165.60.128.1 to 165.60.255.254165.60.255.25532,766
123165.61.0.0/17165.61.0.1 to 165.61.127.254165.61.127.25532,766
124165.61.128.0/17165.61.128.1 to 165.61.255.254165.61.255.25532,766
125165.62.0.0/17165.62.0.1 to 165.62.127.254165.62.127.25532,766
126165.62.128.0/17165.62.128.1 to 165.62.255.254165.62.255.25532,766
127165.63.0.0/17165.63.0.1 to 165.63.127.254165.63.127.25532,766
128165.63.128.0/17165.63.128.1 to 165.63.255.254165.63.255.25532,766
129165.64.0.0/17165.64.0.1 to 165.64.127.254165.64.127.25532,766
130165.64.128.0/17165.64.128.1 to 165.64.255.254165.64.255.25532,766
131165.65.0.0/17165.65.0.1 to 165.65.127.254165.65.127.25532,766
132165.65.128.0/17165.65.128.1 to 165.65.255.254165.65.255.25532,766
133165.66.0.0/17165.66.0.1 to 165.66.127.254165.66.127.25532,766
134165.66.128.0/17165.66.128.1 to 165.66.255.254165.66.255.25532,766
135165.67.0.0/17165.67.0.1 to 165.67.127.254165.67.127.25532,766
136165.67.128.0/17165.67.128.1 to 165.67.255.254165.67.255.25532,766
137165.68.0.0/17165.68.0.1 to 165.68.127.254165.68.127.25532,766
138165.68.128.0/17165.68.128.1 to 165.68.255.254165.68.255.25532,766
139165.69.0.0/17165.69.0.1 to 165.69.127.254165.69.127.25532,766
140165.69.128.0/17165.69.128.1 to 165.69.255.254165.69.255.25532,766
141165.70.0.0/17165.70.0.1 to 165.70.127.254165.70.127.25532,766
142165.70.128.0/17165.70.128.1 to 165.70.255.254165.70.255.25532,766
143165.71.0.0/17165.71.0.1 to 165.71.127.254165.71.127.25532,766
144165.71.128.0/17165.71.128.1 to 165.71.255.254165.71.255.25532,766
145165.72.0.0/17165.72.0.1 to 165.72.127.254165.72.127.25532,766
146165.72.128.0/17165.72.128.1 to 165.72.255.254165.72.255.25532,766
147165.73.0.0/17165.73.0.1 to 165.73.127.254165.73.127.25532,766
148165.73.128.0/17165.73.128.1 to 165.73.255.254165.73.255.25532,766
149165.74.0.0/17165.74.0.1 to 165.74.127.254165.74.127.25532,766
150165.74.128.0/17165.74.128.1 to 165.74.255.254165.74.255.25532,766
151165.75.0.0/17165.75.0.1 to 165.75.127.254165.75.127.25532,766
152165.75.128.0/17165.75.128.1 to 165.75.255.254165.75.255.25532,766
153165.76.0.0/17165.76.0.1 to 165.76.127.254165.76.127.25532,766
154165.76.128.0/17165.76.128.1 to 165.76.255.254165.76.255.25532,766
155165.77.0.0/17165.77.0.1 to 165.77.127.254165.77.127.25532,766
156165.77.128.0/17165.77.128.1 to 165.77.255.254165.77.255.25532,766
157165.78.0.0/17165.78.0.1 to 165.78.127.254165.78.127.25532,766
158165.78.128.0/17165.78.128.1 to 165.78.255.254165.78.255.25532,766
159165.79.0.0/17165.79.0.1 to 165.79.127.254165.79.127.25532,766
160165.79.128.0/17165.79.128.1 to 165.79.255.254165.79.255.25532,766
161165.80.0.0/17165.80.0.1 to 165.80.127.254165.80.127.25532,766
162165.80.128.0/17165.80.128.1 to 165.80.255.254165.80.255.25532,766
163165.81.0.0/17165.81.0.1 to 165.81.127.254165.81.127.25532,766
164165.81.128.0/17165.81.128.1 to 165.81.255.254165.81.255.25532,766
165165.82.0.0/17165.82.0.1 to 165.82.127.254165.82.127.25532,766
166165.82.128.0/17165.82.128.1 to 165.82.255.254165.82.255.25532,766
167165.83.0.0/17165.83.0.1 to 165.83.127.254165.83.127.25532,766
168165.83.128.0/17165.83.128.1 to 165.83.255.254165.83.255.25532,766
169165.84.0.0/17165.84.0.1 to 165.84.127.254165.84.127.25532,766
170165.84.128.0/17165.84.128.1 to 165.84.255.254165.84.255.25532,766
171165.85.0.0/17165.85.0.1 to 165.85.127.254165.85.127.25532,766
172165.85.128.0/17165.85.128.1 to 165.85.255.254165.85.255.25532,766
173165.86.0.0/17165.86.0.1 to 165.86.127.254165.86.127.25532,766
174165.86.128.0/17165.86.128.1 to 165.86.255.254165.86.255.25532,766
175165.87.0.0/17165.87.0.1 to 165.87.127.254165.87.127.25532,766
176165.87.128.0/17165.87.128.1 to 165.87.255.254165.87.255.25532,766
177165.88.0.0/17165.88.0.1 to 165.88.127.254165.88.127.25532,766
178165.88.128.0/17165.88.128.1 to 165.88.255.254165.88.255.25532,766
179165.89.0.0/17165.89.0.1 to 165.89.127.254165.89.127.25532,766
180165.89.128.0/17165.89.128.1 to 165.89.255.254165.89.255.25532,766
181165.90.0.0/17165.90.0.1 to 165.90.127.254165.90.127.25532,766
182165.90.128.0/17165.90.128.1 to 165.90.255.254165.90.255.25532,766
183165.91.0.0/17165.91.0.1 to 165.91.127.254165.91.127.25532,766
184165.91.128.0/17165.91.128.1 to 165.91.255.254165.91.255.25532,766
185165.92.0.0/17165.92.0.1 to 165.92.127.254165.92.127.25532,766
186165.92.128.0/17165.92.128.1 to 165.92.255.254165.92.255.25532,766
187165.93.0.0/17165.93.0.1 to 165.93.127.254165.93.127.25532,766
188165.93.128.0/17165.93.128.1 to 165.93.255.254165.93.255.25532,766
189165.94.0.0/17165.94.0.1 to 165.94.127.254165.94.127.25532,766
190165.94.128.0/17165.94.128.1 to 165.94.255.254165.94.255.25532,766
191165.95.0.0/17165.95.0.1 to 165.95.127.254165.95.127.25532,766
192165.95.128.0/17165.95.128.1 to 165.95.255.254165.95.255.25532,766
193165.96.0.0/17165.96.0.1 to 165.96.127.254165.96.127.25532,766
194165.96.128.0/17165.96.128.1 to 165.96.255.254165.96.255.25532,766
195165.97.0.0/17165.97.0.1 to 165.97.127.254165.97.127.25532,766
196165.97.128.0/17165.97.128.1 to 165.97.255.254165.97.255.25532,766
197165.98.0.0/17165.98.0.1 to 165.98.127.254165.98.127.25532,766
198165.98.128.0/17165.98.128.1 to 165.98.255.254165.98.255.25532,766
199165.99.0.0/17165.99.0.1 to 165.99.127.254165.99.127.25532,766
200165.99.128.0/17165.99.128.1 to 165.99.255.254165.99.255.25532,766
201165.100.0.0/17165.100.0.1 to 165.100.127.254165.100.127.25532,766
202165.100.128.0/17165.100.128.1 to 165.100.255.254165.100.255.25532,766
203165.101.0.0/17165.101.0.1 to 165.101.127.254165.101.127.25532,766
204165.101.128.0/17165.101.128.1 to 165.101.255.254165.101.255.25532,766
205165.102.0.0/17165.102.0.1 to 165.102.127.254165.102.127.25532,766
206165.102.128.0/17165.102.128.1 to 165.102.255.254165.102.255.25532,766
207165.103.0.0/17165.103.0.1 to 165.103.127.254165.103.127.25532,766
208165.103.128.0/17165.103.128.1 to 165.103.255.254165.103.255.25532,766
209165.104.0.0/17165.104.0.1 to 165.104.127.254165.104.127.25532,766
210165.104.128.0/17165.104.128.1 to 165.104.255.254165.104.255.25532,766
211165.105.0.0/17165.105.0.1 to 165.105.127.254165.105.127.25532,766
212165.105.128.0/17165.105.128.1 to 165.105.255.254165.105.255.25532,766
213165.106.0.0/17165.106.0.1 to 165.106.127.254165.106.127.25532,766
214165.106.128.0/17165.106.128.1 to 165.106.255.254165.106.255.25532,766
215165.107.0.0/17165.107.0.1 to 165.107.127.254165.107.127.25532,766
216165.107.128.0/17165.107.128.1 to 165.107.255.254165.107.255.25532,766
217165.108.0.0/17165.108.0.1 to 165.108.127.254165.108.127.25532,766
218165.108.128.0/17165.108.128.1 to 165.108.255.254165.108.255.25532,766
219165.109.0.0/17165.109.0.1 to 165.109.127.254165.109.127.25532,766
220165.109.128.0/17165.109.128.1 to 165.109.255.254165.109.255.25532,766
221165.110.0.0/17165.110.0.1 to 165.110.127.254165.110.127.25532,766
222165.110.128.0/17165.110.128.1 to 165.110.255.254165.110.255.25532,766
223165.111.0.0/17165.111.0.1 to 165.111.127.254165.111.127.25532,766
224165.111.128.0/17165.111.128.1 to 165.111.255.254165.111.255.25532,766
225165.112.0.0/17165.112.0.1 to 165.112.127.254165.112.127.25532,766
226165.112.128.0/17165.112.128.1 to 165.112.255.254165.112.255.25532,766
227165.113.0.0/17165.113.0.1 to 165.113.127.254165.113.127.25532,766
228165.113.128.0/17165.113.128.1 to 165.113.255.254165.113.255.25532,766
229165.114.0.0/17165.114.0.1 to 165.114.127.254165.114.127.25532,766
230165.114.128.0/17165.114.128.1 to 165.114.255.254165.114.255.25532,766
231165.115.0.0/17165.115.0.1 to 165.115.127.254165.115.127.25532,766
232165.115.128.0/17165.115.128.1 to 165.115.255.254165.115.255.25532,766
233165.116.0.0/17165.116.0.1 to 165.116.127.254165.116.127.25532,766
234165.116.128.0/17165.116.128.1 to 165.116.255.254165.116.255.25532,766
235165.117.0.0/17165.117.0.1 to 165.117.127.254165.117.127.25532,766
236165.117.128.0/17165.117.128.1 to 165.117.255.254165.117.255.25532,766
237165.118.0.0/17165.118.0.1 to 165.118.127.254165.118.127.25532,766
238165.118.128.0/17165.118.128.1 to 165.118.255.254165.118.255.25532,766
239165.119.0.0/17165.119.0.1 to 165.119.127.254165.119.127.25532,766
240165.119.128.0/17165.119.128.1 to 165.119.255.254165.119.255.25532,766
241165.120.0.0/17165.120.0.1 to 165.120.127.254165.120.127.25532,766
242165.120.128.0/17165.120.128.1 to 165.120.255.254165.120.255.25532,766
243165.121.0.0/17165.121.0.1 to 165.121.127.254165.121.127.25532,766
244165.121.128.0/17165.121.128.1 to 165.121.255.254165.121.255.25532,766
245165.122.0.0/17165.122.0.1 to 165.122.127.254165.122.127.25532,766
246165.122.128.0/17165.122.128.1 to 165.122.255.254165.122.255.25532,766
247165.123.0.0/17165.123.0.1 to 165.123.127.254165.123.127.25532,766
248165.123.128.0/17165.123.128.1 to 165.123.255.254165.123.255.25532,766
249165.124.0.0/17165.124.0.1 to 165.124.127.254165.124.127.25532,766
250165.124.128.0/17165.124.128.1 to 165.124.255.254165.124.255.25532,766
251165.125.0.0/17165.125.0.1 to 165.125.127.254165.125.127.25532,766
252165.125.128.0/17165.125.128.1 to 165.125.255.254165.125.255.25532,766
253165.126.0.0/17165.126.0.1 to 165.126.127.254165.126.127.25532,766
254165.126.128.0/17165.126.128.1 to 165.126.255.254165.126.255.25532,766
255165.127.0.0/17165.127.0.1 to 165.127.127.254165.127.127.25532,766
256165.127.128.0/17165.127.128.1 to 165.127.255.254165.127.255.25532,766

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.