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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.

Network208.0.0.0/9
Usable hosts8,388,606
Subnet mask255.128.0.0
Addresses8,388,608
Network address
208.0.0.0
Broadcast address
208.127.255.255
First usable
208.0.0.1
Last usable
208.127.255.254
Usable hosts
8,388,606 (8,388,608 less the network and broadcast addresses)
Subnet mask
255.128.0.0
Wildcard mask
0.127.255.255 (Cisco ACLs, OSPF)
Prefix length
/9
Type
Public public
Old class
C (default /24)
As numbers
Hex D0000000 · Integer 3489660928 to 3498049535
Reverse DNS zones
0.208.in-addr.arpa
1.208.in-addr.arpa
2.208.in-addr.arpa
3.208.in-addr.arpa
4.208.in-addr.arpa
5.208.in-addr.arpa
6.208.in-addr.arpa
7.208.in-addr.arpa
8.208.in-addr.arpa
9.208.in-addr.arpa
10.208.in-addr.arpa
11.208.in-addr.arpa
12.208.in-addr.arpa
13.208.in-addr.arpa
14.208.in-addr.arpa
15.208.in-addr.arpa
and 112 more
/9 is not on a 8-bit boundary, so it takes 128 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11010000.00000000.00000000.00000000208.0.0.0
Subnet mask11111111.10000000.00000000.00000000255.128.0.0
Network11010000.00000000.00000000.00000000208.0.0.0
Broadcast11010000.01111111.11111111.11111111208.127.255.255
Split into smaller subnets/18
/10 (2)/11 (4)/12 (8)/13 (16)/14 (32)/15 (64)/16 (128)/17 (256)/18 (512)/19 (1,024)/20 (2,048)/21 (4,096)

208.0.0.0/9 makes 512 subnets of /18; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1208.0.0.0/18208.0.0.1 to 208.0.63.254208.0.63.25516,382
2208.0.64.0/18208.0.64.1 to 208.0.127.254208.0.127.25516,382
3208.0.128.0/18208.0.128.1 to 208.0.191.254208.0.191.25516,382
4208.0.192.0/18208.0.192.1 to 208.0.255.254208.0.255.25516,382
5208.1.0.0/18208.1.0.1 to 208.1.63.254208.1.63.25516,382
6208.1.64.0/18208.1.64.1 to 208.1.127.254208.1.127.25516,382
7208.1.128.0/18208.1.128.1 to 208.1.191.254208.1.191.25516,382
8208.1.192.0/18208.1.192.1 to 208.1.255.254208.1.255.25516,382
9208.2.0.0/18208.2.0.1 to 208.2.63.254208.2.63.25516,382
10208.2.64.0/18208.2.64.1 to 208.2.127.254208.2.127.25516,382
11208.2.128.0/18208.2.128.1 to 208.2.191.254208.2.191.25516,382
12208.2.192.0/18208.2.192.1 to 208.2.255.254208.2.255.25516,382
13208.3.0.0/18208.3.0.1 to 208.3.63.254208.3.63.25516,382
14208.3.64.0/18208.3.64.1 to 208.3.127.254208.3.127.25516,382
15208.3.128.0/18208.3.128.1 to 208.3.191.254208.3.191.25516,382
16208.3.192.0/18208.3.192.1 to 208.3.255.254208.3.255.25516,382
17208.4.0.0/18208.4.0.1 to 208.4.63.254208.4.63.25516,382
18208.4.64.0/18208.4.64.1 to 208.4.127.254208.4.127.25516,382
19208.4.128.0/18208.4.128.1 to 208.4.191.254208.4.191.25516,382
20208.4.192.0/18208.4.192.1 to 208.4.255.254208.4.255.25516,382
21208.5.0.0/18208.5.0.1 to 208.5.63.254208.5.63.25516,382
22208.5.64.0/18208.5.64.1 to 208.5.127.254208.5.127.25516,382
23208.5.128.0/18208.5.128.1 to 208.5.191.254208.5.191.25516,382
24208.5.192.0/18208.5.192.1 to 208.5.255.254208.5.255.25516,382
25208.6.0.0/18208.6.0.1 to 208.6.63.254208.6.63.25516,382
26208.6.64.0/18208.6.64.1 to 208.6.127.254208.6.127.25516,382
27208.6.128.0/18208.6.128.1 to 208.6.191.254208.6.191.25516,382
28208.6.192.0/18208.6.192.1 to 208.6.255.254208.6.255.25516,382
29208.7.0.0/18208.7.0.1 to 208.7.63.254208.7.63.25516,382
30208.7.64.0/18208.7.64.1 to 208.7.127.254208.7.127.25516,382
31208.7.128.0/18208.7.128.1 to 208.7.191.254208.7.191.25516,382
32208.7.192.0/18208.7.192.1 to 208.7.255.254208.7.255.25516,382
33208.8.0.0/18208.8.0.1 to 208.8.63.254208.8.63.25516,382
34208.8.64.0/18208.8.64.1 to 208.8.127.254208.8.127.25516,382
35208.8.128.0/18208.8.128.1 to 208.8.191.254208.8.191.25516,382
36208.8.192.0/18208.8.192.1 to 208.8.255.254208.8.255.25516,382
37208.9.0.0/18208.9.0.1 to 208.9.63.254208.9.63.25516,382
38208.9.64.0/18208.9.64.1 to 208.9.127.254208.9.127.25516,382
39208.9.128.0/18208.9.128.1 to 208.9.191.254208.9.191.25516,382
40208.9.192.0/18208.9.192.1 to 208.9.255.254208.9.255.25516,382
41208.10.0.0/18208.10.0.1 to 208.10.63.254208.10.63.25516,382
42208.10.64.0/18208.10.64.1 to 208.10.127.254208.10.127.25516,382
43208.10.128.0/18208.10.128.1 to 208.10.191.254208.10.191.25516,382
44208.10.192.0/18208.10.192.1 to 208.10.255.254208.10.255.25516,382
45208.11.0.0/18208.11.0.1 to 208.11.63.254208.11.63.25516,382
46208.11.64.0/18208.11.64.1 to 208.11.127.254208.11.127.25516,382
47208.11.128.0/18208.11.128.1 to 208.11.191.254208.11.191.25516,382
48208.11.192.0/18208.11.192.1 to 208.11.255.254208.11.255.25516,382
49208.12.0.0/18208.12.0.1 to 208.12.63.254208.12.63.25516,382
50208.12.64.0/18208.12.64.1 to 208.12.127.254208.12.127.25516,382
51208.12.128.0/18208.12.128.1 to 208.12.191.254208.12.191.25516,382
52208.12.192.0/18208.12.192.1 to 208.12.255.254208.12.255.25516,382
53208.13.0.0/18208.13.0.1 to 208.13.63.254208.13.63.25516,382
54208.13.64.0/18208.13.64.1 to 208.13.127.254208.13.127.25516,382
55208.13.128.0/18208.13.128.1 to 208.13.191.254208.13.191.25516,382
56208.13.192.0/18208.13.192.1 to 208.13.255.254208.13.255.25516,382
57208.14.0.0/18208.14.0.1 to 208.14.63.254208.14.63.25516,382
58208.14.64.0/18208.14.64.1 to 208.14.127.254208.14.127.25516,382
59208.14.128.0/18208.14.128.1 to 208.14.191.254208.14.191.25516,382
60208.14.192.0/18208.14.192.1 to 208.14.255.254208.14.255.25516,382
61208.15.0.0/18208.15.0.1 to 208.15.63.254208.15.63.25516,382
62208.15.64.0/18208.15.64.1 to 208.15.127.254208.15.127.25516,382
63208.15.128.0/18208.15.128.1 to 208.15.191.254208.15.191.25516,382
64208.15.192.0/18208.15.192.1 to 208.15.255.254208.15.255.25516,382
65208.16.0.0/18208.16.0.1 to 208.16.63.254208.16.63.25516,382
66208.16.64.0/18208.16.64.1 to 208.16.127.254208.16.127.25516,382
67208.16.128.0/18208.16.128.1 to 208.16.191.254208.16.191.25516,382
68208.16.192.0/18208.16.192.1 to 208.16.255.254208.16.255.25516,382
69208.17.0.0/18208.17.0.1 to 208.17.63.254208.17.63.25516,382
70208.17.64.0/18208.17.64.1 to 208.17.127.254208.17.127.25516,382
71208.17.128.0/18208.17.128.1 to 208.17.191.254208.17.191.25516,382
72208.17.192.0/18208.17.192.1 to 208.17.255.254208.17.255.25516,382
73208.18.0.0/18208.18.0.1 to 208.18.63.254208.18.63.25516,382
74208.18.64.0/18208.18.64.1 to 208.18.127.254208.18.127.25516,382
75208.18.128.0/18208.18.128.1 to 208.18.191.254208.18.191.25516,382
76208.18.192.0/18208.18.192.1 to 208.18.255.254208.18.255.25516,382
77208.19.0.0/18208.19.0.1 to 208.19.63.254208.19.63.25516,382
78208.19.64.0/18208.19.64.1 to 208.19.127.254208.19.127.25516,382
79208.19.128.0/18208.19.128.1 to 208.19.191.254208.19.191.25516,382
80208.19.192.0/18208.19.192.1 to 208.19.255.254208.19.255.25516,382
81208.20.0.0/18208.20.0.1 to 208.20.63.254208.20.63.25516,382
82208.20.64.0/18208.20.64.1 to 208.20.127.254208.20.127.25516,382
83208.20.128.0/18208.20.128.1 to 208.20.191.254208.20.191.25516,382
84208.20.192.0/18208.20.192.1 to 208.20.255.254208.20.255.25516,382
85208.21.0.0/18208.21.0.1 to 208.21.63.254208.21.63.25516,382
86208.21.64.0/18208.21.64.1 to 208.21.127.254208.21.127.25516,382
87208.21.128.0/18208.21.128.1 to 208.21.191.254208.21.191.25516,382
88208.21.192.0/18208.21.192.1 to 208.21.255.254208.21.255.25516,382
89208.22.0.0/18208.22.0.1 to 208.22.63.254208.22.63.25516,382
90208.22.64.0/18208.22.64.1 to 208.22.127.254208.22.127.25516,382
91208.22.128.0/18208.22.128.1 to 208.22.191.254208.22.191.25516,382
92208.22.192.0/18208.22.192.1 to 208.22.255.254208.22.255.25516,382
93208.23.0.0/18208.23.0.1 to 208.23.63.254208.23.63.25516,382
94208.23.64.0/18208.23.64.1 to 208.23.127.254208.23.127.25516,382
95208.23.128.0/18208.23.128.1 to 208.23.191.254208.23.191.25516,382
96208.23.192.0/18208.23.192.1 to 208.23.255.254208.23.255.25516,382
97208.24.0.0/18208.24.0.1 to 208.24.63.254208.24.63.25516,382
98208.24.64.0/18208.24.64.1 to 208.24.127.254208.24.127.25516,382
99208.24.128.0/18208.24.128.1 to 208.24.191.254208.24.191.25516,382
100208.24.192.0/18208.24.192.1 to 208.24.255.254208.24.255.25516,382
101208.25.0.0/18208.25.0.1 to 208.25.63.254208.25.63.25516,382
102208.25.64.0/18208.25.64.1 to 208.25.127.254208.25.127.25516,382
103208.25.128.0/18208.25.128.1 to 208.25.191.254208.25.191.25516,382
104208.25.192.0/18208.25.192.1 to 208.25.255.254208.25.255.25516,382
105208.26.0.0/18208.26.0.1 to 208.26.63.254208.26.63.25516,382
106208.26.64.0/18208.26.64.1 to 208.26.127.254208.26.127.25516,382
107208.26.128.0/18208.26.128.1 to 208.26.191.254208.26.191.25516,382
108208.26.192.0/18208.26.192.1 to 208.26.255.254208.26.255.25516,382
109208.27.0.0/18208.27.0.1 to 208.27.63.254208.27.63.25516,382
110208.27.64.0/18208.27.64.1 to 208.27.127.254208.27.127.25516,382
111208.27.128.0/18208.27.128.1 to 208.27.191.254208.27.191.25516,382
112208.27.192.0/18208.27.192.1 to 208.27.255.254208.27.255.25516,382
113208.28.0.0/18208.28.0.1 to 208.28.63.254208.28.63.25516,382
114208.28.64.0/18208.28.64.1 to 208.28.127.254208.28.127.25516,382
115208.28.128.0/18208.28.128.1 to 208.28.191.254208.28.191.25516,382
116208.28.192.0/18208.28.192.1 to 208.28.255.254208.28.255.25516,382
117208.29.0.0/18208.29.0.1 to 208.29.63.254208.29.63.25516,382
118208.29.64.0/18208.29.64.1 to 208.29.127.254208.29.127.25516,382
119208.29.128.0/18208.29.128.1 to 208.29.191.254208.29.191.25516,382
120208.29.192.0/18208.29.192.1 to 208.29.255.254208.29.255.25516,382
121208.30.0.0/18208.30.0.1 to 208.30.63.254208.30.63.25516,382
122208.30.64.0/18208.30.64.1 to 208.30.127.254208.30.127.25516,382
123208.30.128.0/18208.30.128.1 to 208.30.191.254208.30.191.25516,382
124208.30.192.0/18208.30.192.1 to 208.30.255.254208.30.255.25516,382
125208.31.0.0/18208.31.0.1 to 208.31.63.254208.31.63.25516,382
126208.31.64.0/18208.31.64.1 to 208.31.127.254208.31.127.25516,382
127208.31.128.0/18208.31.128.1 to 208.31.191.254208.31.191.25516,382
128208.31.192.0/18208.31.192.1 to 208.31.255.254208.31.255.25516,382
129208.32.0.0/18208.32.0.1 to 208.32.63.254208.32.63.25516,382
130208.32.64.0/18208.32.64.1 to 208.32.127.254208.32.127.25516,382
131208.32.128.0/18208.32.128.1 to 208.32.191.254208.32.191.25516,382
132208.32.192.0/18208.32.192.1 to 208.32.255.254208.32.255.25516,382
133208.33.0.0/18208.33.0.1 to 208.33.63.254208.33.63.25516,382
134208.33.64.0/18208.33.64.1 to 208.33.127.254208.33.127.25516,382
135208.33.128.0/18208.33.128.1 to 208.33.191.254208.33.191.25516,382
136208.33.192.0/18208.33.192.1 to 208.33.255.254208.33.255.25516,382
137208.34.0.0/18208.34.0.1 to 208.34.63.254208.34.63.25516,382
138208.34.64.0/18208.34.64.1 to 208.34.127.254208.34.127.25516,382
139208.34.128.0/18208.34.128.1 to 208.34.191.254208.34.191.25516,382
140208.34.192.0/18208.34.192.1 to 208.34.255.254208.34.255.25516,382
141208.35.0.0/18208.35.0.1 to 208.35.63.254208.35.63.25516,382
142208.35.64.0/18208.35.64.1 to 208.35.127.254208.35.127.25516,382
143208.35.128.0/18208.35.128.1 to 208.35.191.254208.35.191.25516,382
144208.35.192.0/18208.35.192.1 to 208.35.255.254208.35.255.25516,382
145208.36.0.0/18208.36.0.1 to 208.36.63.254208.36.63.25516,382
146208.36.64.0/18208.36.64.1 to 208.36.127.254208.36.127.25516,382
147208.36.128.0/18208.36.128.1 to 208.36.191.254208.36.191.25516,382
148208.36.192.0/18208.36.192.1 to 208.36.255.254208.36.255.25516,382
149208.37.0.0/18208.37.0.1 to 208.37.63.254208.37.63.25516,382
150208.37.64.0/18208.37.64.1 to 208.37.127.254208.37.127.25516,382
151208.37.128.0/18208.37.128.1 to 208.37.191.254208.37.191.25516,382
152208.37.192.0/18208.37.192.1 to 208.37.255.254208.37.255.25516,382
153208.38.0.0/18208.38.0.1 to 208.38.63.254208.38.63.25516,382
154208.38.64.0/18208.38.64.1 to 208.38.127.254208.38.127.25516,382
155208.38.128.0/18208.38.128.1 to 208.38.191.254208.38.191.25516,382
156208.38.192.0/18208.38.192.1 to 208.38.255.254208.38.255.25516,382
157208.39.0.0/18208.39.0.1 to 208.39.63.254208.39.63.25516,382
158208.39.64.0/18208.39.64.1 to 208.39.127.254208.39.127.25516,382
159208.39.128.0/18208.39.128.1 to 208.39.191.254208.39.191.25516,382
160208.39.192.0/18208.39.192.1 to 208.39.255.254208.39.255.25516,382
161208.40.0.0/18208.40.0.1 to 208.40.63.254208.40.63.25516,382
162208.40.64.0/18208.40.64.1 to 208.40.127.254208.40.127.25516,382
163208.40.128.0/18208.40.128.1 to 208.40.191.254208.40.191.25516,382
164208.40.192.0/18208.40.192.1 to 208.40.255.254208.40.255.25516,382
165208.41.0.0/18208.41.0.1 to 208.41.63.254208.41.63.25516,382
166208.41.64.0/18208.41.64.1 to 208.41.127.254208.41.127.25516,382
167208.41.128.0/18208.41.128.1 to 208.41.191.254208.41.191.25516,382
168208.41.192.0/18208.41.192.1 to 208.41.255.254208.41.255.25516,382
169208.42.0.0/18208.42.0.1 to 208.42.63.254208.42.63.25516,382
170208.42.64.0/18208.42.64.1 to 208.42.127.254208.42.127.25516,382
171208.42.128.0/18208.42.128.1 to 208.42.191.254208.42.191.25516,382
172208.42.192.0/18208.42.192.1 to 208.42.255.254208.42.255.25516,382
173208.43.0.0/18208.43.0.1 to 208.43.63.254208.43.63.25516,382
174208.43.64.0/18208.43.64.1 to 208.43.127.254208.43.127.25516,382
175208.43.128.0/18208.43.128.1 to 208.43.191.254208.43.191.25516,382
176208.43.192.0/18208.43.192.1 to 208.43.255.254208.43.255.25516,382
177208.44.0.0/18208.44.0.1 to 208.44.63.254208.44.63.25516,382
178208.44.64.0/18208.44.64.1 to 208.44.127.254208.44.127.25516,382
179208.44.128.0/18208.44.128.1 to 208.44.191.254208.44.191.25516,382
180208.44.192.0/18208.44.192.1 to 208.44.255.254208.44.255.25516,382
181208.45.0.0/18208.45.0.1 to 208.45.63.254208.45.63.25516,382
182208.45.64.0/18208.45.64.1 to 208.45.127.254208.45.127.25516,382
183208.45.128.0/18208.45.128.1 to 208.45.191.254208.45.191.25516,382
184208.45.192.0/18208.45.192.1 to 208.45.255.254208.45.255.25516,382
185208.46.0.0/18208.46.0.1 to 208.46.63.254208.46.63.25516,382
186208.46.64.0/18208.46.64.1 to 208.46.127.254208.46.127.25516,382
187208.46.128.0/18208.46.128.1 to 208.46.191.254208.46.191.25516,382
188208.46.192.0/18208.46.192.1 to 208.46.255.254208.46.255.25516,382
189208.47.0.0/18208.47.0.1 to 208.47.63.254208.47.63.25516,382
190208.47.64.0/18208.47.64.1 to 208.47.127.254208.47.127.25516,382
191208.47.128.0/18208.47.128.1 to 208.47.191.254208.47.191.25516,382
192208.47.192.0/18208.47.192.1 to 208.47.255.254208.47.255.25516,382
193208.48.0.0/18208.48.0.1 to 208.48.63.254208.48.63.25516,382
194208.48.64.0/18208.48.64.1 to 208.48.127.254208.48.127.25516,382
195208.48.128.0/18208.48.128.1 to 208.48.191.254208.48.191.25516,382
196208.48.192.0/18208.48.192.1 to 208.48.255.254208.48.255.25516,382
197208.49.0.0/18208.49.0.1 to 208.49.63.254208.49.63.25516,382
198208.49.64.0/18208.49.64.1 to 208.49.127.254208.49.127.25516,382
199208.49.128.0/18208.49.128.1 to 208.49.191.254208.49.191.25516,382
200208.49.192.0/18208.49.192.1 to 208.49.255.254208.49.255.25516,382
201208.50.0.0/18208.50.0.1 to 208.50.63.254208.50.63.25516,382
202208.50.64.0/18208.50.64.1 to 208.50.127.254208.50.127.25516,382
203208.50.128.0/18208.50.128.1 to 208.50.191.254208.50.191.25516,382
204208.50.192.0/18208.50.192.1 to 208.50.255.254208.50.255.25516,382
205208.51.0.0/18208.51.0.1 to 208.51.63.254208.51.63.25516,382
206208.51.64.0/18208.51.64.1 to 208.51.127.254208.51.127.25516,382
207208.51.128.0/18208.51.128.1 to 208.51.191.254208.51.191.25516,382
208208.51.192.0/18208.51.192.1 to 208.51.255.254208.51.255.25516,382
209208.52.0.0/18208.52.0.1 to 208.52.63.254208.52.63.25516,382
210208.52.64.0/18208.52.64.1 to 208.52.127.254208.52.127.25516,382
211208.52.128.0/18208.52.128.1 to 208.52.191.254208.52.191.25516,382
212208.52.192.0/18208.52.192.1 to 208.52.255.254208.52.255.25516,382
213208.53.0.0/18208.53.0.1 to 208.53.63.254208.53.63.25516,382
214208.53.64.0/18208.53.64.1 to 208.53.127.254208.53.127.25516,382
215208.53.128.0/18208.53.128.1 to 208.53.191.254208.53.191.25516,382
216208.53.192.0/18208.53.192.1 to 208.53.255.254208.53.255.25516,382
217208.54.0.0/18208.54.0.1 to 208.54.63.254208.54.63.25516,382
218208.54.64.0/18208.54.64.1 to 208.54.127.254208.54.127.25516,382
219208.54.128.0/18208.54.128.1 to 208.54.191.254208.54.191.25516,382
220208.54.192.0/18208.54.192.1 to 208.54.255.254208.54.255.25516,382
221208.55.0.0/18208.55.0.1 to 208.55.63.254208.55.63.25516,382
222208.55.64.0/18208.55.64.1 to 208.55.127.254208.55.127.25516,382
223208.55.128.0/18208.55.128.1 to 208.55.191.254208.55.191.25516,382
224208.55.192.0/18208.55.192.1 to 208.55.255.254208.55.255.25516,382
225208.56.0.0/18208.56.0.1 to 208.56.63.254208.56.63.25516,382
226208.56.64.0/18208.56.64.1 to 208.56.127.254208.56.127.25516,382
227208.56.128.0/18208.56.128.1 to 208.56.191.254208.56.191.25516,382
228208.56.192.0/18208.56.192.1 to 208.56.255.254208.56.255.25516,382
229208.57.0.0/18208.57.0.1 to 208.57.63.254208.57.63.25516,382
230208.57.64.0/18208.57.64.1 to 208.57.127.254208.57.127.25516,382
231208.57.128.0/18208.57.128.1 to 208.57.191.254208.57.191.25516,382
232208.57.192.0/18208.57.192.1 to 208.57.255.254208.57.255.25516,382
233208.58.0.0/18208.58.0.1 to 208.58.63.254208.58.63.25516,382
234208.58.64.0/18208.58.64.1 to 208.58.127.254208.58.127.25516,382
235208.58.128.0/18208.58.128.1 to 208.58.191.254208.58.191.25516,382
236208.58.192.0/18208.58.192.1 to 208.58.255.254208.58.255.25516,382
237208.59.0.0/18208.59.0.1 to 208.59.63.254208.59.63.25516,382
238208.59.64.0/18208.59.64.1 to 208.59.127.254208.59.127.25516,382
239208.59.128.0/18208.59.128.1 to 208.59.191.254208.59.191.25516,382
240208.59.192.0/18208.59.192.1 to 208.59.255.254208.59.255.25516,382
241208.60.0.0/18208.60.0.1 to 208.60.63.254208.60.63.25516,382
242208.60.64.0/18208.60.64.1 to 208.60.127.254208.60.127.25516,382
243208.60.128.0/18208.60.128.1 to 208.60.191.254208.60.191.25516,382
244208.60.192.0/18208.60.192.1 to 208.60.255.254208.60.255.25516,382
245208.61.0.0/18208.61.0.1 to 208.61.63.254208.61.63.25516,382
246208.61.64.0/18208.61.64.1 to 208.61.127.254208.61.127.25516,382
247208.61.128.0/18208.61.128.1 to 208.61.191.254208.61.191.25516,382
248208.61.192.0/18208.61.192.1 to 208.61.255.254208.61.255.25516,382
249208.62.0.0/18208.62.0.1 to 208.62.63.254208.62.63.25516,382
250208.62.64.0/18208.62.64.1 to 208.62.127.254208.62.127.25516,382
251208.62.128.0/18208.62.128.1 to 208.62.191.254208.62.191.25516,382
252208.62.192.0/18208.62.192.1 to 208.62.255.254208.62.255.25516,382
253208.63.0.0/18208.63.0.1 to 208.63.63.254208.63.63.25516,382
254208.63.64.0/18208.63.64.1 to 208.63.127.254208.63.127.25516,382
255208.63.128.0/18208.63.128.1 to 208.63.191.254208.63.191.25516,382
256208.63.192.0/18208.63.192.1 to 208.63.255.254208.63.255.25516,382

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.