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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.

Network171.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
171.0.0.0
Broadcast address
171.255.255.255
First usable
171.0.0.1
Last usable
171.255.255.254
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 AB000000 · Integer 2868903936 to 2885681151
Reverse DNS zone
171.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10101011..00000000.00000000.00000000171.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network10101011..00000000.00000000.00000000171.0.0.0
Broadcast10101011..11111111.11111111.11111111171.255.255.255
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)

171.0.0.0/8 makes 512 subnets of /17; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1171.0.0.0/17171.0.0.1 to 171.0.127.254171.0.127.25532,766
2171.0.128.0/17171.0.128.1 to 171.0.255.254171.0.255.25532,766
3171.1.0.0/17171.1.0.1 to 171.1.127.254171.1.127.25532,766
4171.1.128.0/17171.1.128.1 to 171.1.255.254171.1.255.25532,766
5171.2.0.0/17171.2.0.1 to 171.2.127.254171.2.127.25532,766
6171.2.128.0/17171.2.128.1 to 171.2.255.254171.2.255.25532,766
7171.3.0.0/17171.3.0.1 to 171.3.127.254171.3.127.25532,766
8171.3.128.0/17171.3.128.1 to 171.3.255.254171.3.255.25532,766
9171.4.0.0/17171.4.0.1 to 171.4.127.254171.4.127.25532,766
10171.4.128.0/17171.4.128.1 to 171.4.255.254171.4.255.25532,766
11171.5.0.0/17171.5.0.1 to 171.5.127.254171.5.127.25532,766
12171.5.128.0/17171.5.128.1 to 171.5.255.254171.5.255.25532,766
13171.6.0.0/17171.6.0.1 to 171.6.127.254171.6.127.25532,766
14171.6.128.0/17171.6.128.1 to 171.6.255.254171.6.255.25532,766
15171.7.0.0/17171.7.0.1 to 171.7.127.254171.7.127.25532,766
16171.7.128.0/17171.7.128.1 to 171.7.255.254171.7.255.25532,766
17171.8.0.0/17171.8.0.1 to 171.8.127.254171.8.127.25532,766
18171.8.128.0/17171.8.128.1 to 171.8.255.254171.8.255.25532,766
19171.9.0.0/17171.9.0.1 to 171.9.127.254171.9.127.25532,766
20171.9.128.0/17171.9.128.1 to 171.9.255.254171.9.255.25532,766
21171.10.0.0/17171.10.0.1 to 171.10.127.254171.10.127.25532,766
22171.10.128.0/17171.10.128.1 to 171.10.255.254171.10.255.25532,766
23171.11.0.0/17171.11.0.1 to 171.11.127.254171.11.127.25532,766
24171.11.128.0/17171.11.128.1 to 171.11.255.254171.11.255.25532,766
25171.12.0.0/17171.12.0.1 to 171.12.127.254171.12.127.25532,766
26171.12.128.0/17171.12.128.1 to 171.12.255.254171.12.255.25532,766
27171.13.0.0/17171.13.0.1 to 171.13.127.254171.13.127.25532,766
28171.13.128.0/17171.13.128.1 to 171.13.255.254171.13.255.25532,766
29171.14.0.0/17171.14.0.1 to 171.14.127.254171.14.127.25532,766
30171.14.128.0/17171.14.128.1 to 171.14.255.254171.14.255.25532,766
31171.15.0.0/17171.15.0.1 to 171.15.127.254171.15.127.25532,766
32171.15.128.0/17171.15.128.1 to 171.15.255.254171.15.255.25532,766
33171.16.0.0/17171.16.0.1 to 171.16.127.254171.16.127.25532,766
34171.16.128.0/17171.16.128.1 to 171.16.255.254171.16.255.25532,766
35171.17.0.0/17171.17.0.1 to 171.17.127.254171.17.127.25532,766
36171.17.128.0/17171.17.128.1 to 171.17.255.254171.17.255.25532,766
37171.18.0.0/17171.18.0.1 to 171.18.127.254171.18.127.25532,766
38171.18.128.0/17171.18.128.1 to 171.18.255.254171.18.255.25532,766
39171.19.0.0/17171.19.0.1 to 171.19.127.254171.19.127.25532,766
40171.19.128.0/17171.19.128.1 to 171.19.255.254171.19.255.25532,766
41171.20.0.0/17171.20.0.1 to 171.20.127.254171.20.127.25532,766
42171.20.128.0/17171.20.128.1 to 171.20.255.254171.20.255.25532,766
43171.21.0.0/17171.21.0.1 to 171.21.127.254171.21.127.25532,766
44171.21.128.0/17171.21.128.1 to 171.21.255.254171.21.255.25532,766
45171.22.0.0/17171.22.0.1 to 171.22.127.254171.22.127.25532,766
46171.22.128.0/17171.22.128.1 to 171.22.255.254171.22.255.25532,766
47171.23.0.0/17171.23.0.1 to 171.23.127.254171.23.127.25532,766
48171.23.128.0/17171.23.128.1 to 171.23.255.254171.23.255.25532,766
49171.24.0.0/17171.24.0.1 to 171.24.127.254171.24.127.25532,766
50171.24.128.0/17171.24.128.1 to 171.24.255.254171.24.255.25532,766
51171.25.0.0/17171.25.0.1 to 171.25.127.254171.25.127.25532,766
52171.25.128.0/17171.25.128.1 to 171.25.255.254171.25.255.25532,766
53171.26.0.0/17171.26.0.1 to 171.26.127.254171.26.127.25532,766
54171.26.128.0/17171.26.128.1 to 171.26.255.254171.26.255.25532,766
55171.27.0.0/17171.27.0.1 to 171.27.127.254171.27.127.25532,766
56171.27.128.0/17171.27.128.1 to 171.27.255.254171.27.255.25532,766
57171.28.0.0/17171.28.0.1 to 171.28.127.254171.28.127.25532,766
58171.28.128.0/17171.28.128.1 to 171.28.255.254171.28.255.25532,766
59171.29.0.0/17171.29.0.1 to 171.29.127.254171.29.127.25532,766
60171.29.128.0/17171.29.128.1 to 171.29.255.254171.29.255.25532,766
61171.30.0.0/17171.30.0.1 to 171.30.127.254171.30.127.25532,766
62171.30.128.0/17171.30.128.1 to 171.30.255.254171.30.255.25532,766
63171.31.0.0/17171.31.0.1 to 171.31.127.254171.31.127.25532,766
64171.31.128.0/17171.31.128.1 to 171.31.255.254171.31.255.25532,766
65171.32.0.0/17171.32.0.1 to 171.32.127.254171.32.127.25532,766
66171.32.128.0/17171.32.128.1 to 171.32.255.254171.32.255.25532,766
67171.33.0.0/17171.33.0.1 to 171.33.127.254171.33.127.25532,766
68171.33.128.0/17171.33.128.1 to 171.33.255.254171.33.255.25532,766
69171.34.0.0/17171.34.0.1 to 171.34.127.254171.34.127.25532,766
70171.34.128.0/17171.34.128.1 to 171.34.255.254171.34.255.25532,766
71171.35.0.0/17171.35.0.1 to 171.35.127.254171.35.127.25532,766
72171.35.128.0/17171.35.128.1 to 171.35.255.254171.35.255.25532,766
73171.36.0.0/17171.36.0.1 to 171.36.127.254171.36.127.25532,766
74171.36.128.0/17171.36.128.1 to 171.36.255.254171.36.255.25532,766
75171.37.0.0/17171.37.0.1 to 171.37.127.254171.37.127.25532,766
76171.37.128.0/17171.37.128.1 to 171.37.255.254171.37.255.25532,766
77171.38.0.0/17171.38.0.1 to 171.38.127.254171.38.127.25532,766
78171.38.128.0/17171.38.128.1 to 171.38.255.254171.38.255.25532,766
79171.39.0.0/17171.39.0.1 to 171.39.127.254171.39.127.25532,766
80171.39.128.0/17171.39.128.1 to 171.39.255.254171.39.255.25532,766
81171.40.0.0/17171.40.0.1 to 171.40.127.254171.40.127.25532,766
82171.40.128.0/17171.40.128.1 to 171.40.255.254171.40.255.25532,766
83171.41.0.0/17171.41.0.1 to 171.41.127.254171.41.127.25532,766
84171.41.128.0/17171.41.128.1 to 171.41.255.254171.41.255.25532,766
85171.42.0.0/17171.42.0.1 to 171.42.127.254171.42.127.25532,766
86171.42.128.0/17171.42.128.1 to 171.42.255.254171.42.255.25532,766
87171.43.0.0/17171.43.0.1 to 171.43.127.254171.43.127.25532,766
88171.43.128.0/17171.43.128.1 to 171.43.255.254171.43.255.25532,766
89171.44.0.0/17171.44.0.1 to 171.44.127.254171.44.127.25532,766
90171.44.128.0/17171.44.128.1 to 171.44.255.254171.44.255.25532,766
91171.45.0.0/17171.45.0.1 to 171.45.127.254171.45.127.25532,766
92171.45.128.0/17171.45.128.1 to 171.45.255.254171.45.255.25532,766
93171.46.0.0/17171.46.0.1 to 171.46.127.254171.46.127.25532,766
94171.46.128.0/17171.46.128.1 to 171.46.255.254171.46.255.25532,766
95171.47.0.0/17171.47.0.1 to 171.47.127.254171.47.127.25532,766
96171.47.128.0/17171.47.128.1 to 171.47.255.254171.47.255.25532,766
97171.48.0.0/17171.48.0.1 to 171.48.127.254171.48.127.25532,766
98171.48.128.0/17171.48.128.1 to 171.48.255.254171.48.255.25532,766
99171.49.0.0/17171.49.0.1 to 171.49.127.254171.49.127.25532,766
100171.49.128.0/17171.49.128.1 to 171.49.255.254171.49.255.25532,766
101171.50.0.0/17171.50.0.1 to 171.50.127.254171.50.127.25532,766
102171.50.128.0/17171.50.128.1 to 171.50.255.254171.50.255.25532,766
103171.51.0.0/17171.51.0.1 to 171.51.127.254171.51.127.25532,766
104171.51.128.0/17171.51.128.1 to 171.51.255.254171.51.255.25532,766
105171.52.0.0/17171.52.0.1 to 171.52.127.254171.52.127.25532,766
106171.52.128.0/17171.52.128.1 to 171.52.255.254171.52.255.25532,766
107171.53.0.0/17171.53.0.1 to 171.53.127.254171.53.127.25532,766
108171.53.128.0/17171.53.128.1 to 171.53.255.254171.53.255.25532,766
109171.54.0.0/17171.54.0.1 to 171.54.127.254171.54.127.25532,766
110171.54.128.0/17171.54.128.1 to 171.54.255.254171.54.255.25532,766
111171.55.0.0/17171.55.0.1 to 171.55.127.254171.55.127.25532,766
112171.55.128.0/17171.55.128.1 to 171.55.255.254171.55.255.25532,766
113171.56.0.0/17171.56.0.1 to 171.56.127.254171.56.127.25532,766
114171.56.128.0/17171.56.128.1 to 171.56.255.254171.56.255.25532,766
115171.57.0.0/17171.57.0.1 to 171.57.127.254171.57.127.25532,766
116171.57.128.0/17171.57.128.1 to 171.57.255.254171.57.255.25532,766
117171.58.0.0/17171.58.0.1 to 171.58.127.254171.58.127.25532,766
118171.58.128.0/17171.58.128.1 to 171.58.255.254171.58.255.25532,766
119171.59.0.0/17171.59.0.1 to 171.59.127.254171.59.127.25532,766
120171.59.128.0/17171.59.128.1 to 171.59.255.254171.59.255.25532,766
121171.60.0.0/17171.60.0.1 to 171.60.127.254171.60.127.25532,766
122171.60.128.0/17171.60.128.1 to 171.60.255.254171.60.255.25532,766
123171.61.0.0/17171.61.0.1 to 171.61.127.254171.61.127.25532,766
124171.61.128.0/17171.61.128.1 to 171.61.255.254171.61.255.25532,766
125171.62.0.0/17171.62.0.1 to 171.62.127.254171.62.127.25532,766
126171.62.128.0/17171.62.128.1 to 171.62.255.254171.62.255.25532,766
127171.63.0.0/17171.63.0.1 to 171.63.127.254171.63.127.25532,766
128171.63.128.0/17171.63.128.1 to 171.63.255.254171.63.255.25532,766
129171.64.0.0/17171.64.0.1 to 171.64.127.254171.64.127.25532,766
130171.64.128.0/17171.64.128.1 to 171.64.255.254171.64.255.25532,766
131171.65.0.0/17171.65.0.1 to 171.65.127.254171.65.127.25532,766
132171.65.128.0/17171.65.128.1 to 171.65.255.254171.65.255.25532,766
133171.66.0.0/17171.66.0.1 to 171.66.127.254171.66.127.25532,766
134171.66.128.0/17171.66.128.1 to 171.66.255.254171.66.255.25532,766
135171.67.0.0/17171.67.0.1 to 171.67.127.254171.67.127.25532,766
136171.67.128.0/17171.67.128.1 to 171.67.255.254171.67.255.25532,766
137171.68.0.0/17171.68.0.1 to 171.68.127.254171.68.127.25532,766
138171.68.128.0/17171.68.128.1 to 171.68.255.254171.68.255.25532,766
139171.69.0.0/17171.69.0.1 to 171.69.127.254171.69.127.25532,766
140171.69.128.0/17171.69.128.1 to 171.69.255.254171.69.255.25532,766
141171.70.0.0/17171.70.0.1 to 171.70.127.254171.70.127.25532,766
142171.70.128.0/17171.70.128.1 to 171.70.255.254171.70.255.25532,766
143171.71.0.0/17171.71.0.1 to 171.71.127.254171.71.127.25532,766
144171.71.128.0/17171.71.128.1 to 171.71.255.254171.71.255.25532,766
145171.72.0.0/17171.72.0.1 to 171.72.127.254171.72.127.25532,766
146171.72.128.0/17171.72.128.1 to 171.72.255.254171.72.255.25532,766
147171.73.0.0/17171.73.0.1 to 171.73.127.254171.73.127.25532,766
148171.73.128.0/17171.73.128.1 to 171.73.255.254171.73.255.25532,766
149171.74.0.0/17171.74.0.1 to 171.74.127.254171.74.127.25532,766
150171.74.128.0/17171.74.128.1 to 171.74.255.254171.74.255.25532,766
151171.75.0.0/17171.75.0.1 to 171.75.127.254171.75.127.25532,766
152171.75.128.0/17171.75.128.1 to 171.75.255.254171.75.255.25532,766
153171.76.0.0/17171.76.0.1 to 171.76.127.254171.76.127.25532,766
154171.76.128.0/17171.76.128.1 to 171.76.255.254171.76.255.25532,766
155171.77.0.0/17171.77.0.1 to 171.77.127.254171.77.127.25532,766
156171.77.128.0/17171.77.128.1 to 171.77.255.254171.77.255.25532,766
157171.78.0.0/17171.78.0.1 to 171.78.127.254171.78.127.25532,766
158171.78.128.0/17171.78.128.1 to 171.78.255.254171.78.255.25532,766
159171.79.0.0/17171.79.0.1 to 171.79.127.254171.79.127.25532,766
160171.79.128.0/17171.79.128.1 to 171.79.255.254171.79.255.25532,766
161171.80.0.0/17171.80.0.1 to 171.80.127.254171.80.127.25532,766
162171.80.128.0/17171.80.128.1 to 171.80.255.254171.80.255.25532,766
163171.81.0.0/17171.81.0.1 to 171.81.127.254171.81.127.25532,766
164171.81.128.0/17171.81.128.1 to 171.81.255.254171.81.255.25532,766
165171.82.0.0/17171.82.0.1 to 171.82.127.254171.82.127.25532,766
166171.82.128.0/17171.82.128.1 to 171.82.255.254171.82.255.25532,766
167171.83.0.0/17171.83.0.1 to 171.83.127.254171.83.127.25532,766
168171.83.128.0/17171.83.128.1 to 171.83.255.254171.83.255.25532,766
169171.84.0.0/17171.84.0.1 to 171.84.127.254171.84.127.25532,766
170171.84.128.0/17171.84.128.1 to 171.84.255.254171.84.255.25532,766
171171.85.0.0/17171.85.0.1 to 171.85.127.254171.85.127.25532,766
172171.85.128.0/17171.85.128.1 to 171.85.255.254171.85.255.25532,766
173171.86.0.0/17171.86.0.1 to 171.86.127.254171.86.127.25532,766
174171.86.128.0/17171.86.128.1 to 171.86.255.254171.86.255.25532,766
175171.87.0.0/17171.87.0.1 to 171.87.127.254171.87.127.25532,766
176171.87.128.0/17171.87.128.1 to 171.87.255.254171.87.255.25532,766
177171.88.0.0/17171.88.0.1 to 171.88.127.254171.88.127.25532,766
178171.88.128.0/17171.88.128.1 to 171.88.255.254171.88.255.25532,766
179171.89.0.0/17171.89.0.1 to 171.89.127.254171.89.127.25532,766
180171.89.128.0/17171.89.128.1 to 171.89.255.254171.89.255.25532,766
181171.90.0.0/17171.90.0.1 to 171.90.127.254171.90.127.25532,766
182171.90.128.0/17171.90.128.1 to 171.90.255.254171.90.255.25532,766
183171.91.0.0/17171.91.0.1 to 171.91.127.254171.91.127.25532,766
184171.91.128.0/17171.91.128.1 to 171.91.255.254171.91.255.25532,766
185171.92.0.0/17171.92.0.1 to 171.92.127.254171.92.127.25532,766
186171.92.128.0/17171.92.128.1 to 171.92.255.254171.92.255.25532,766
187171.93.0.0/17171.93.0.1 to 171.93.127.254171.93.127.25532,766
188171.93.128.0/17171.93.128.1 to 171.93.255.254171.93.255.25532,766
189171.94.0.0/17171.94.0.1 to 171.94.127.254171.94.127.25532,766
190171.94.128.0/17171.94.128.1 to 171.94.255.254171.94.255.25532,766
191171.95.0.0/17171.95.0.1 to 171.95.127.254171.95.127.25532,766
192171.95.128.0/17171.95.128.1 to 171.95.255.254171.95.255.25532,766
193171.96.0.0/17171.96.0.1 to 171.96.127.254171.96.127.25532,766
194171.96.128.0/17171.96.128.1 to 171.96.255.254171.96.255.25532,766
195171.97.0.0/17171.97.0.1 to 171.97.127.254171.97.127.25532,766
196171.97.128.0/17171.97.128.1 to 171.97.255.254171.97.255.25532,766
197171.98.0.0/17171.98.0.1 to 171.98.127.254171.98.127.25532,766
198171.98.128.0/17171.98.128.1 to 171.98.255.254171.98.255.25532,766
199171.99.0.0/17171.99.0.1 to 171.99.127.254171.99.127.25532,766
200171.99.128.0/17171.99.128.1 to 171.99.255.254171.99.255.25532,766
201171.100.0.0/17171.100.0.1 to 171.100.127.254171.100.127.25532,766
202171.100.128.0/17171.100.128.1 to 171.100.255.254171.100.255.25532,766
203171.101.0.0/17171.101.0.1 to 171.101.127.254171.101.127.25532,766
204171.101.128.0/17171.101.128.1 to 171.101.255.254171.101.255.25532,766
205171.102.0.0/17171.102.0.1 to 171.102.127.254171.102.127.25532,766
206171.102.128.0/17171.102.128.1 to 171.102.255.254171.102.255.25532,766
207171.103.0.0/17171.103.0.1 to 171.103.127.254171.103.127.25532,766
208171.103.128.0/17171.103.128.1 to 171.103.255.254171.103.255.25532,766
209171.104.0.0/17171.104.0.1 to 171.104.127.254171.104.127.25532,766
210171.104.128.0/17171.104.128.1 to 171.104.255.254171.104.255.25532,766
211171.105.0.0/17171.105.0.1 to 171.105.127.254171.105.127.25532,766
212171.105.128.0/17171.105.128.1 to 171.105.255.254171.105.255.25532,766
213171.106.0.0/17171.106.0.1 to 171.106.127.254171.106.127.25532,766
214171.106.128.0/17171.106.128.1 to 171.106.255.254171.106.255.25532,766
215171.107.0.0/17171.107.0.1 to 171.107.127.254171.107.127.25532,766
216171.107.128.0/17171.107.128.1 to 171.107.255.254171.107.255.25532,766
217171.108.0.0/17171.108.0.1 to 171.108.127.254171.108.127.25532,766
218171.108.128.0/17171.108.128.1 to 171.108.255.254171.108.255.25532,766
219171.109.0.0/17171.109.0.1 to 171.109.127.254171.109.127.25532,766
220171.109.128.0/17171.109.128.1 to 171.109.255.254171.109.255.25532,766
221171.110.0.0/17171.110.0.1 to 171.110.127.254171.110.127.25532,766
222171.110.128.0/17171.110.128.1 to 171.110.255.254171.110.255.25532,766
223171.111.0.0/17171.111.0.1 to 171.111.127.254171.111.127.25532,766
224171.111.128.0/17171.111.128.1 to 171.111.255.254171.111.255.25532,766
225171.112.0.0/17171.112.0.1 to 171.112.127.254171.112.127.25532,766
226171.112.128.0/17171.112.128.1 to 171.112.255.254171.112.255.25532,766
227171.113.0.0/17171.113.0.1 to 171.113.127.254171.113.127.25532,766
228171.113.128.0/17171.113.128.1 to 171.113.255.254171.113.255.25532,766
229171.114.0.0/17171.114.0.1 to 171.114.127.254171.114.127.25532,766
230171.114.128.0/17171.114.128.1 to 171.114.255.254171.114.255.25532,766
231171.115.0.0/17171.115.0.1 to 171.115.127.254171.115.127.25532,766
232171.115.128.0/17171.115.128.1 to 171.115.255.254171.115.255.25532,766
233171.116.0.0/17171.116.0.1 to 171.116.127.254171.116.127.25532,766
234171.116.128.0/17171.116.128.1 to 171.116.255.254171.116.255.25532,766
235171.117.0.0/17171.117.0.1 to 171.117.127.254171.117.127.25532,766
236171.117.128.0/17171.117.128.1 to 171.117.255.254171.117.255.25532,766
237171.118.0.0/17171.118.0.1 to 171.118.127.254171.118.127.25532,766
238171.118.128.0/17171.118.128.1 to 171.118.255.254171.118.255.25532,766
239171.119.0.0/17171.119.0.1 to 171.119.127.254171.119.127.25532,766
240171.119.128.0/17171.119.128.1 to 171.119.255.254171.119.255.25532,766
241171.120.0.0/17171.120.0.1 to 171.120.127.254171.120.127.25532,766
242171.120.128.0/17171.120.128.1 to 171.120.255.254171.120.255.25532,766
243171.121.0.0/17171.121.0.1 to 171.121.127.254171.121.127.25532,766
244171.121.128.0/17171.121.128.1 to 171.121.255.254171.121.255.25532,766
245171.122.0.0/17171.122.0.1 to 171.122.127.254171.122.127.25532,766
246171.122.128.0/17171.122.128.1 to 171.122.255.254171.122.255.25532,766
247171.123.0.0/17171.123.0.1 to 171.123.127.254171.123.127.25532,766
248171.123.128.0/17171.123.128.1 to 171.123.255.254171.123.255.25532,766
249171.124.0.0/17171.124.0.1 to 171.124.127.254171.124.127.25532,766
250171.124.128.0/17171.124.128.1 to 171.124.255.254171.124.255.25532,766
251171.125.0.0/17171.125.0.1 to 171.125.127.254171.125.127.25532,766
252171.125.128.0/17171.125.128.1 to 171.125.255.254171.125.255.25532,766
253171.126.0.0/17171.126.0.1 to 171.126.127.254171.126.127.25532,766
254171.126.128.0/17171.126.128.1 to 171.126.255.254171.126.255.25532,766
255171.127.0.0/17171.127.0.1 to 171.127.127.254171.127.127.25532,766
256171.127.128.0/17171.127.128.1 to 171.127.255.254171.127.255.25532,766

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.