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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.

Network181.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
181.0.0.0
Broadcast address
181.255.255.255
First usable
181.0.0.1
Last usable
181.255.255.254
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 B5000000 · Integer 3036676096 to 3053453311
Reverse DNS zone
181.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10110101..00000000.00000000.00000000181.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network10110101..00000000.00000000.00000000181.0.0.0
Broadcast10110101..11111111.11111111.11111111181.255.255.255
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)

181.0.0.0/8 makes 512 subnets of /17; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1181.0.0.0/17181.0.0.1 to 181.0.127.254181.0.127.25532,766
2181.0.128.0/17181.0.128.1 to 181.0.255.254181.0.255.25532,766
3181.1.0.0/17181.1.0.1 to 181.1.127.254181.1.127.25532,766
4181.1.128.0/17181.1.128.1 to 181.1.255.254181.1.255.25532,766
5181.2.0.0/17181.2.0.1 to 181.2.127.254181.2.127.25532,766
6181.2.128.0/17181.2.128.1 to 181.2.255.254181.2.255.25532,766
7181.3.0.0/17181.3.0.1 to 181.3.127.254181.3.127.25532,766
8181.3.128.0/17181.3.128.1 to 181.3.255.254181.3.255.25532,766
9181.4.0.0/17181.4.0.1 to 181.4.127.254181.4.127.25532,766
10181.4.128.0/17181.4.128.1 to 181.4.255.254181.4.255.25532,766
11181.5.0.0/17181.5.0.1 to 181.5.127.254181.5.127.25532,766
12181.5.128.0/17181.5.128.1 to 181.5.255.254181.5.255.25532,766
13181.6.0.0/17181.6.0.1 to 181.6.127.254181.6.127.25532,766
14181.6.128.0/17181.6.128.1 to 181.6.255.254181.6.255.25532,766
15181.7.0.0/17181.7.0.1 to 181.7.127.254181.7.127.25532,766
16181.7.128.0/17181.7.128.1 to 181.7.255.254181.7.255.25532,766
17181.8.0.0/17181.8.0.1 to 181.8.127.254181.8.127.25532,766
18181.8.128.0/17181.8.128.1 to 181.8.255.254181.8.255.25532,766
19181.9.0.0/17181.9.0.1 to 181.9.127.254181.9.127.25532,766
20181.9.128.0/17181.9.128.1 to 181.9.255.254181.9.255.25532,766
21181.10.0.0/17181.10.0.1 to 181.10.127.254181.10.127.25532,766
22181.10.128.0/17181.10.128.1 to 181.10.255.254181.10.255.25532,766
23181.11.0.0/17181.11.0.1 to 181.11.127.254181.11.127.25532,766
24181.11.128.0/17181.11.128.1 to 181.11.255.254181.11.255.25532,766
25181.12.0.0/17181.12.0.1 to 181.12.127.254181.12.127.25532,766
26181.12.128.0/17181.12.128.1 to 181.12.255.254181.12.255.25532,766
27181.13.0.0/17181.13.0.1 to 181.13.127.254181.13.127.25532,766
28181.13.128.0/17181.13.128.1 to 181.13.255.254181.13.255.25532,766
29181.14.0.0/17181.14.0.1 to 181.14.127.254181.14.127.25532,766
30181.14.128.0/17181.14.128.1 to 181.14.255.254181.14.255.25532,766
31181.15.0.0/17181.15.0.1 to 181.15.127.254181.15.127.25532,766
32181.15.128.0/17181.15.128.1 to 181.15.255.254181.15.255.25532,766
33181.16.0.0/17181.16.0.1 to 181.16.127.254181.16.127.25532,766
34181.16.128.0/17181.16.128.1 to 181.16.255.254181.16.255.25532,766
35181.17.0.0/17181.17.0.1 to 181.17.127.254181.17.127.25532,766
36181.17.128.0/17181.17.128.1 to 181.17.255.254181.17.255.25532,766
37181.18.0.0/17181.18.0.1 to 181.18.127.254181.18.127.25532,766
38181.18.128.0/17181.18.128.1 to 181.18.255.254181.18.255.25532,766
39181.19.0.0/17181.19.0.1 to 181.19.127.254181.19.127.25532,766
40181.19.128.0/17181.19.128.1 to 181.19.255.254181.19.255.25532,766
41181.20.0.0/17181.20.0.1 to 181.20.127.254181.20.127.25532,766
42181.20.128.0/17181.20.128.1 to 181.20.255.254181.20.255.25532,766
43181.21.0.0/17181.21.0.1 to 181.21.127.254181.21.127.25532,766
44181.21.128.0/17181.21.128.1 to 181.21.255.254181.21.255.25532,766
45181.22.0.0/17181.22.0.1 to 181.22.127.254181.22.127.25532,766
46181.22.128.0/17181.22.128.1 to 181.22.255.254181.22.255.25532,766
47181.23.0.0/17181.23.0.1 to 181.23.127.254181.23.127.25532,766
48181.23.128.0/17181.23.128.1 to 181.23.255.254181.23.255.25532,766
49181.24.0.0/17181.24.0.1 to 181.24.127.254181.24.127.25532,766
50181.24.128.0/17181.24.128.1 to 181.24.255.254181.24.255.25532,766
51181.25.0.0/17181.25.0.1 to 181.25.127.254181.25.127.25532,766
52181.25.128.0/17181.25.128.1 to 181.25.255.254181.25.255.25532,766
53181.26.0.0/17181.26.0.1 to 181.26.127.254181.26.127.25532,766
54181.26.128.0/17181.26.128.1 to 181.26.255.254181.26.255.25532,766
55181.27.0.0/17181.27.0.1 to 181.27.127.254181.27.127.25532,766
56181.27.128.0/17181.27.128.1 to 181.27.255.254181.27.255.25532,766
57181.28.0.0/17181.28.0.1 to 181.28.127.254181.28.127.25532,766
58181.28.128.0/17181.28.128.1 to 181.28.255.254181.28.255.25532,766
59181.29.0.0/17181.29.0.1 to 181.29.127.254181.29.127.25532,766
60181.29.128.0/17181.29.128.1 to 181.29.255.254181.29.255.25532,766
61181.30.0.0/17181.30.0.1 to 181.30.127.254181.30.127.25532,766
62181.30.128.0/17181.30.128.1 to 181.30.255.254181.30.255.25532,766
63181.31.0.0/17181.31.0.1 to 181.31.127.254181.31.127.25532,766
64181.31.128.0/17181.31.128.1 to 181.31.255.254181.31.255.25532,766
65181.32.0.0/17181.32.0.1 to 181.32.127.254181.32.127.25532,766
66181.32.128.0/17181.32.128.1 to 181.32.255.254181.32.255.25532,766
67181.33.0.0/17181.33.0.1 to 181.33.127.254181.33.127.25532,766
68181.33.128.0/17181.33.128.1 to 181.33.255.254181.33.255.25532,766
69181.34.0.0/17181.34.0.1 to 181.34.127.254181.34.127.25532,766
70181.34.128.0/17181.34.128.1 to 181.34.255.254181.34.255.25532,766
71181.35.0.0/17181.35.0.1 to 181.35.127.254181.35.127.25532,766
72181.35.128.0/17181.35.128.1 to 181.35.255.254181.35.255.25532,766
73181.36.0.0/17181.36.0.1 to 181.36.127.254181.36.127.25532,766
74181.36.128.0/17181.36.128.1 to 181.36.255.254181.36.255.25532,766
75181.37.0.0/17181.37.0.1 to 181.37.127.254181.37.127.25532,766
76181.37.128.0/17181.37.128.1 to 181.37.255.254181.37.255.25532,766
77181.38.0.0/17181.38.0.1 to 181.38.127.254181.38.127.25532,766
78181.38.128.0/17181.38.128.1 to 181.38.255.254181.38.255.25532,766
79181.39.0.0/17181.39.0.1 to 181.39.127.254181.39.127.25532,766
80181.39.128.0/17181.39.128.1 to 181.39.255.254181.39.255.25532,766
81181.40.0.0/17181.40.0.1 to 181.40.127.254181.40.127.25532,766
82181.40.128.0/17181.40.128.1 to 181.40.255.254181.40.255.25532,766
83181.41.0.0/17181.41.0.1 to 181.41.127.254181.41.127.25532,766
84181.41.128.0/17181.41.128.1 to 181.41.255.254181.41.255.25532,766
85181.42.0.0/17181.42.0.1 to 181.42.127.254181.42.127.25532,766
86181.42.128.0/17181.42.128.1 to 181.42.255.254181.42.255.25532,766
87181.43.0.0/17181.43.0.1 to 181.43.127.254181.43.127.25532,766
88181.43.128.0/17181.43.128.1 to 181.43.255.254181.43.255.25532,766
89181.44.0.0/17181.44.0.1 to 181.44.127.254181.44.127.25532,766
90181.44.128.0/17181.44.128.1 to 181.44.255.254181.44.255.25532,766
91181.45.0.0/17181.45.0.1 to 181.45.127.254181.45.127.25532,766
92181.45.128.0/17181.45.128.1 to 181.45.255.254181.45.255.25532,766
93181.46.0.0/17181.46.0.1 to 181.46.127.254181.46.127.25532,766
94181.46.128.0/17181.46.128.1 to 181.46.255.254181.46.255.25532,766
95181.47.0.0/17181.47.0.1 to 181.47.127.254181.47.127.25532,766
96181.47.128.0/17181.47.128.1 to 181.47.255.254181.47.255.25532,766
97181.48.0.0/17181.48.0.1 to 181.48.127.254181.48.127.25532,766
98181.48.128.0/17181.48.128.1 to 181.48.255.254181.48.255.25532,766
99181.49.0.0/17181.49.0.1 to 181.49.127.254181.49.127.25532,766
100181.49.128.0/17181.49.128.1 to 181.49.255.254181.49.255.25532,766
101181.50.0.0/17181.50.0.1 to 181.50.127.254181.50.127.25532,766
102181.50.128.0/17181.50.128.1 to 181.50.255.254181.50.255.25532,766
103181.51.0.0/17181.51.0.1 to 181.51.127.254181.51.127.25532,766
104181.51.128.0/17181.51.128.1 to 181.51.255.254181.51.255.25532,766
105181.52.0.0/17181.52.0.1 to 181.52.127.254181.52.127.25532,766
106181.52.128.0/17181.52.128.1 to 181.52.255.254181.52.255.25532,766
107181.53.0.0/17181.53.0.1 to 181.53.127.254181.53.127.25532,766
108181.53.128.0/17181.53.128.1 to 181.53.255.254181.53.255.25532,766
109181.54.0.0/17181.54.0.1 to 181.54.127.254181.54.127.25532,766
110181.54.128.0/17181.54.128.1 to 181.54.255.254181.54.255.25532,766
111181.55.0.0/17181.55.0.1 to 181.55.127.254181.55.127.25532,766
112181.55.128.0/17181.55.128.1 to 181.55.255.254181.55.255.25532,766
113181.56.0.0/17181.56.0.1 to 181.56.127.254181.56.127.25532,766
114181.56.128.0/17181.56.128.1 to 181.56.255.254181.56.255.25532,766
115181.57.0.0/17181.57.0.1 to 181.57.127.254181.57.127.25532,766
116181.57.128.0/17181.57.128.1 to 181.57.255.254181.57.255.25532,766
117181.58.0.0/17181.58.0.1 to 181.58.127.254181.58.127.25532,766
118181.58.128.0/17181.58.128.1 to 181.58.255.254181.58.255.25532,766
119181.59.0.0/17181.59.0.1 to 181.59.127.254181.59.127.25532,766
120181.59.128.0/17181.59.128.1 to 181.59.255.254181.59.255.25532,766
121181.60.0.0/17181.60.0.1 to 181.60.127.254181.60.127.25532,766
122181.60.128.0/17181.60.128.1 to 181.60.255.254181.60.255.25532,766
123181.61.0.0/17181.61.0.1 to 181.61.127.254181.61.127.25532,766
124181.61.128.0/17181.61.128.1 to 181.61.255.254181.61.255.25532,766
125181.62.0.0/17181.62.0.1 to 181.62.127.254181.62.127.25532,766
126181.62.128.0/17181.62.128.1 to 181.62.255.254181.62.255.25532,766
127181.63.0.0/17181.63.0.1 to 181.63.127.254181.63.127.25532,766
128181.63.128.0/17181.63.128.1 to 181.63.255.254181.63.255.25532,766
129181.64.0.0/17181.64.0.1 to 181.64.127.254181.64.127.25532,766
130181.64.128.0/17181.64.128.1 to 181.64.255.254181.64.255.25532,766
131181.65.0.0/17181.65.0.1 to 181.65.127.254181.65.127.25532,766
132181.65.128.0/17181.65.128.1 to 181.65.255.254181.65.255.25532,766
133181.66.0.0/17181.66.0.1 to 181.66.127.254181.66.127.25532,766
134181.66.128.0/17181.66.128.1 to 181.66.255.254181.66.255.25532,766
135181.67.0.0/17181.67.0.1 to 181.67.127.254181.67.127.25532,766
136181.67.128.0/17181.67.128.1 to 181.67.255.254181.67.255.25532,766
137181.68.0.0/17181.68.0.1 to 181.68.127.254181.68.127.25532,766
138181.68.128.0/17181.68.128.1 to 181.68.255.254181.68.255.25532,766
139181.69.0.0/17181.69.0.1 to 181.69.127.254181.69.127.25532,766
140181.69.128.0/17181.69.128.1 to 181.69.255.254181.69.255.25532,766
141181.70.0.0/17181.70.0.1 to 181.70.127.254181.70.127.25532,766
142181.70.128.0/17181.70.128.1 to 181.70.255.254181.70.255.25532,766
143181.71.0.0/17181.71.0.1 to 181.71.127.254181.71.127.25532,766
144181.71.128.0/17181.71.128.1 to 181.71.255.254181.71.255.25532,766
145181.72.0.0/17181.72.0.1 to 181.72.127.254181.72.127.25532,766
146181.72.128.0/17181.72.128.1 to 181.72.255.254181.72.255.25532,766
147181.73.0.0/17181.73.0.1 to 181.73.127.254181.73.127.25532,766
148181.73.128.0/17181.73.128.1 to 181.73.255.254181.73.255.25532,766
149181.74.0.0/17181.74.0.1 to 181.74.127.254181.74.127.25532,766
150181.74.128.0/17181.74.128.1 to 181.74.255.254181.74.255.25532,766
151181.75.0.0/17181.75.0.1 to 181.75.127.254181.75.127.25532,766
152181.75.128.0/17181.75.128.1 to 181.75.255.254181.75.255.25532,766
153181.76.0.0/17181.76.0.1 to 181.76.127.254181.76.127.25532,766
154181.76.128.0/17181.76.128.1 to 181.76.255.254181.76.255.25532,766
155181.77.0.0/17181.77.0.1 to 181.77.127.254181.77.127.25532,766
156181.77.128.0/17181.77.128.1 to 181.77.255.254181.77.255.25532,766
157181.78.0.0/17181.78.0.1 to 181.78.127.254181.78.127.25532,766
158181.78.128.0/17181.78.128.1 to 181.78.255.254181.78.255.25532,766
159181.79.0.0/17181.79.0.1 to 181.79.127.254181.79.127.25532,766
160181.79.128.0/17181.79.128.1 to 181.79.255.254181.79.255.25532,766
161181.80.0.0/17181.80.0.1 to 181.80.127.254181.80.127.25532,766
162181.80.128.0/17181.80.128.1 to 181.80.255.254181.80.255.25532,766
163181.81.0.0/17181.81.0.1 to 181.81.127.254181.81.127.25532,766
164181.81.128.0/17181.81.128.1 to 181.81.255.254181.81.255.25532,766
165181.82.0.0/17181.82.0.1 to 181.82.127.254181.82.127.25532,766
166181.82.128.0/17181.82.128.1 to 181.82.255.254181.82.255.25532,766
167181.83.0.0/17181.83.0.1 to 181.83.127.254181.83.127.25532,766
168181.83.128.0/17181.83.128.1 to 181.83.255.254181.83.255.25532,766
169181.84.0.0/17181.84.0.1 to 181.84.127.254181.84.127.25532,766
170181.84.128.0/17181.84.128.1 to 181.84.255.254181.84.255.25532,766
171181.85.0.0/17181.85.0.1 to 181.85.127.254181.85.127.25532,766
172181.85.128.0/17181.85.128.1 to 181.85.255.254181.85.255.25532,766
173181.86.0.0/17181.86.0.1 to 181.86.127.254181.86.127.25532,766
174181.86.128.0/17181.86.128.1 to 181.86.255.254181.86.255.25532,766
175181.87.0.0/17181.87.0.1 to 181.87.127.254181.87.127.25532,766
176181.87.128.0/17181.87.128.1 to 181.87.255.254181.87.255.25532,766
177181.88.0.0/17181.88.0.1 to 181.88.127.254181.88.127.25532,766
178181.88.128.0/17181.88.128.1 to 181.88.255.254181.88.255.25532,766
179181.89.0.0/17181.89.0.1 to 181.89.127.254181.89.127.25532,766
180181.89.128.0/17181.89.128.1 to 181.89.255.254181.89.255.25532,766
181181.90.0.0/17181.90.0.1 to 181.90.127.254181.90.127.25532,766
182181.90.128.0/17181.90.128.1 to 181.90.255.254181.90.255.25532,766
183181.91.0.0/17181.91.0.1 to 181.91.127.254181.91.127.25532,766
184181.91.128.0/17181.91.128.1 to 181.91.255.254181.91.255.25532,766
185181.92.0.0/17181.92.0.1 to 181.92.127.254181.92.127.25532,766
186181.92.128.0/17181.92.128.1 to 181.92.255.254181.92.255.25532,766
187181.93.0.0/17181.93.0.1 to 181.93.127.254181.93.127.25532,766
188181.93.128.0/17181.93.128.1 to 181.93.255.254181.93.255.25532,766
189181.94.0.0/17181.94.0.1 to 181.94.127.254181.94.127.25532,766
190181.94.128.0/17181.94.128.1 to 181.94.255.254181.94.255.25532,766
191181.95.0.0/17181.95.0.1 to 181.95.127.254181.95.127.25532,766
192181.95.128.0/17181.95.128.1 to 181.95.255.254181.95.255.25532,766
193181.96.0.0/17181.96.0.1 to 181.96.127.254181.96.127.25532,766
194181.96.128.0/17181.96.128.1 to 181.96.255.254181.96.255.25532,766
195181.97.0.0/17181.97.0.1 to 181.97.127.254181.97.127.25532,766
196181.97.128.0/17181.97.128.1 to 181.97.255.254181.97.255.25532,766
197181.98.0.0/17181.98.0.1 to 181.98.127.254181.98.127.25532,766
198181.98.128.0/17181.98.128.1 to 181.98.255.254181.98.255.25532,766
199181.99.0.0/17181.99.0.1 to 181.99.127.254181.99.127.25532,766
200181.99.128.0/17181.99.128.1 to 181.99.255.254181.99.255.25532,766
201181.100.0.0/17181.100.0.1 to 181.100.127.254181.100.127.25532,766
202181.100.128.0/17181.100.128.1 to 181.100.255.254181.100.255.25532,766
203181.101.0.0/17181.101.0.1 to 181.101.127.254181.101.127.25532,766
204181.101.128.0/17181.101.128.1 to 181.101.255.254181.101.255.25532,766
205181.102.0.0/17181.102.0.1 to 181.102.127.254181.102.127.25532,766
206181.102.128.0/17181.102.128.1 to 181.102.255.254181.102.255.25532,766
207181.103.0.0/17181.103.0.1 to 181.103.127.254181.103.127.25532,766
208181.103.128.0/17181.103.128.1 to 181.103.255.254181.103.255.25532,766
209181.104.0.0/17181.104.0.1 to 181.104.127.254181.104.127.25532,766
210181.104.128.0/17181.104.128.1 to 181.104.255.254181.104.255.25532,766
211181.105.0.0/17181.105.0.1 to 181.105.127.254181.105.127.25532,766
212181.105.128.0/17181.105.128.1 to 181.105.255.254181.105.255.25532,766
213181.106.0.0/17181.106.0.1 to 181.106.127.254181.106.127.25532,766
214181.106.128.0/17181.106.128.1 to 181.106.255.254181.106.255.25532,766
215181.107.0.0/17181.107.0.1 to 181.107.127.254181.107.127.25532,766
216181.107.128.0/17181.107.128.1 to 181.107.255.254181.107.255.25532,766
217181.108.0.0/17181.108.0.1 to 181.108.127.254181.108.127.25532,766
218181.108.128.0/17181.108.128.1 to 181.108.255.254181.108.255.25532,766
219181.109.0.0/17181.109.0.1 to 181.109.127.254181.109.127.25532,766
220181.109.128.0/17181.109.128.1 to 181.109.255.254181.109.255.25532,766
221181.110.0.0/17181.110.0.1 to 181.110.127.254181.110.127.25532,766
222181.110.128.0/17181.110.128.1 to 181.110.255.254181.110.255.25532,766
223181.111.0.0/17181.111.0.1 to 181.111.127.254181.111.127.25532,766
224181.111.128.0/17181.111.128.1 to 181.111.255.254181.111.255.25532,766
225181.112.0.0/17181.112.0.1 to 181.112.127.254181.112.127.25532,766
226181.112.128.0/17181.112.128.1 to 181.112.255.254181.112.255.25532,766
227181.113.0.0/17181.113.0.1 to 181.113.127.254181.113.127.25532,766
228181.113.128.0/17181.113.128.1 to 181.113.255.254181.113.255.25532,766
229181.114.0.0/17181.114.0.1 to 181.114.127.254181.114.127.25532,766
230181.114.128.0/17181.114.128.1 to 181.114.255.254181.114.255.25532,766
231181.115.0.0/17181.115.0.1 to 181.115.127.254181.115.127.25532,766
232181.115.128.0/17181.115.128.1 to 181.115.255.254181.115.255.25532,766
233181.116.0.0/17181.116.0.1 to 181.116.127.254181.116.127.25532,766
234181.116.128.0/17181.116.128.1 to 181.116.255.254181.116.255.25532,766
235181.117.0.0/17181.117.0.1 to 181.117.127.254181.117.127.25532,766
236181.117.128.0/17181.117.128.1 to 181.117.255.254181.117.255.25532,766
237181.118.0.0/17181.118.0.1 to 181.118.127.254181.118.127.25532,766
238181.118.128.0/17181.118.128.1 to 181.118.255.254181.118.255.25532,766
239181.119.0.0/17181.119.0.1 to 181.119.127.254181.119.127.25532,766
240181.119.128.0/17181.119.128.1 to 181.119.255.254181.119.255.25532,766
241181.120.0.0/17181.120.0.1 to 181.120.127.254181.120.127.25532,766
242181.120.128.0/17181.120.128.1 to 181.120.255.254181.120.255.25532,766
243181.121.0.0/17181.121.0.1 to 181.121.127.254181.121.127.25532,766
244181.121.128.0/17181.121.128.1 to 181.121.255.254181.121.255.25532,766
245181.122.0.0/17181.122.0.1 to 181.122.127.254181.122.127.25532,766
246181.122.128.0/17181.122.128.1 to 181.122.255.254181.122.255.25532,766
247181.123.0.0/17181.123.0.1 to 181.123.127.254181.123.127.25532,766
248181.123.128.0/17181.123.128.1 to 181.123.255.254181.123.255.25532,766
249181.124.0.0/17181.124.0.1 to 181.124.127.254181.124.127.25532,766
250181.124.128.0/17181.124.128.1 to 181.124.255.254181.124.255.25532,766
251181.125.0.0/17181.125.0.1 to 181.125.127.254181.125.127.25532,766
252181.125.128.0/17181.125.128.1 to 181.125.255.254181.125.255.25532,766
253181.126.0.0/17181.126.0.1 to 181.126.127.254181.126.127.25532,766
254181.126.128.0/17181.126.128.1 to 181.126.255.254181.126.255.25532,766
255181.127.0.0/17181.127.0.1 to 181.127.127.254181.127.127.25532,766
256181.127.128.0/17181.127.128.1 to 181.127.255.254181.127.255.25532,766

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.