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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.

Network211.0.0.0/9
Usable hosts8,388,606
Subnet mask255.128.0.0
Addresses8,388,608
Network address
211.0.0.0
Broadcast address
211.127.255.255
First usable
211.0.0.1
Last usable
211.127.255.254
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 D3000000 · Integer 3539992576 to 3548381183
Reverse DNS zones
0.211.in-addr.arpa
1.211.in-addr.arpa
2.211.in-addr.arpa
3.211.in-addr.arpa
4.211.in-addr.arpa
5.211.in-addr.arpa
6.211.in-addr.arpa
7.211.in-addr.arpa
8.211.in-addr.arpa
9.211.in-addr.arpa
10.211.in-addr.arpa
11.211.in-addr.arpa
12.211.in-addr.arpa
13.211.in-addr.arpa
14.211.in-addr.arpa
15.211.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
Address11010011.00000000.00000000.00000000211.0.0.0
Subnet mask11111111.10000000.00000000.00000000255.128.0.0
Network11010011.00000000.00000000.00000000211.0.0.0
Broadcast11010011.01111111.11111111.11111111211.127.255.255
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)

211.0.0.0/9 makes 512 subnets of /18; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1211.0.0.0/18211.0.0.1 to 211.0.63.254211.0.63.25516,382
2211.0.64.0/18211.0.64.1 to 211.0.127.254211.0.127.25516,382
3211.0.128.0/18211.0.128.1 to 211.0.191.254211.0.191.25516,382
4211.0.192.0/18211.0.192.1 to 211.0.255.254211.0.255.25516,382
5211.1.0.0/18211.1.0.1 to 211.1.63.254211.1.63.25516,382
6211.1.64.0/18211.1.64.1 to 211.1.127.254211.1.127.25516,382
7211.1.128.0/18211.1.128.1 to 211.1.191.254211.1.191.25516,382
8211.1.192.0/18211.1.192.1 to 211.1.255.254211.1.255.25516,382
9211.2.0.0/18211.2.0.1 to 211.2.63.254211.2.63.25516,382
10211.2.64.0/18211.2.64.1 to 211.2.127.254211.2.127.25516,382
11211.2.128.0/18211.2.128.1 to 211.2.191.254211.2.191.25516,382
12211.2.192.0/18211.2.192.1 to 211.2.255.254211.2.255.25516,382
13211.3.0.0/18211.3.0.1 to 211.3.63.254211.3.63.25516,382
14211.3.64.0/18211.3.64.1 to 211.3.127.254211.3.127.25516,382
15211.3.128.0/18211.3.128.1 to 211.3.191.254211.3.191.25516,382
16211.3.192.0/18211.3.192.1 to 211.3.255.254211.3.255.25516,382
17211.4.0.0/18211.4.0.1 to 211.4.63.254211.4.63.25516,382
18211.4.64.0/18211.4.64.1 to 211.4.127.254211.4.127.25516,382
19211.4.128.0/18211.4.128.1 to 211.4.191.254211.4.191.25516,382
20211.4.192.0/18211.4.192.1 to 211.4.255.254211.4.255.25516,382
21211.5.0.0/18211.5.0.1 to 211.5.63.254211.5.63.25516,382
22211.5.64.0/18211.5.64.1 to 211.5.127.254211.5.127.25516,382
23211.5.128.0/18211.5.128.1 to 211.5.191.254211.5.191.25516,382
24211.5.192.0/18211.5.192.1 to 211.5.255.254211.5.255.25516,382
25211.6.0.0/18211.6.0.1 to 211.6.63.254211.6.63.25516,382
26211.6.64.0/18211.6.64.1 to 211.6.127.254211.6.127.25516,382
27211.6.128.0/18211.6.128.1 to 211.6.191.254211.6.191.25516,382
28211.6.192.0/18211.6.192.1 to 211.6.255.254211.6.255.25516,382
29211.7.0.0/18211.7.0.1 to 211.7.63.254211.7.63.25516,382
30211.7.64.0/18211.7.64.1 to 211.7.127.254211.7.127.25516,382
31211.7.128.0/18211.7.128.1 to 211.7.191.254211.7.191.25516,382
32211.7.192.0/18211.7.192.1 to 211.7.255.254211.7.255.25516,382
33211.8.0.0/18211.8.0.1 to 211.8.63.254211.8.63.25516,382
34211.8.64.0/18211.8.64.1 to 211.8.127.254211.8.127.25516,382
35211.8.128.0/18211.8.128.1 to 211.8.191.254211.8.191.25516,382
36211.8.192.0/18211.8.192.1 to 211.8.255.254211.8.255.25516,382
37211.9.0.0/18211.9.0.1 to 211.9.63.254211.9.63.25516,382
38211.9.64.0/18211.9.64.1 to 211.9.127.254211.9.127.25516,382
39211.9.128.0/18211.9.128.1 to 211.9.191.254211.9.191.25516,382
40211.9.192.0/18211.9.192.1 to 211.9.255.254211.9.255.25516,382
41211.10.0.0/18211.10.0.1 to 211.10.63.254211.10.63.25516,382
42211.10.64.0/18211.10.64.1 to 211.10.127.254211.10.127.25516,382
43211.10.128.0/18211.10.128.1 to 211.10.191.254211.10.191.25516,382
44211.10.192.0/18211.10.192.1 to 211.10.255.254211.10.255.25516,382
45211.11.0.0/18211.11.0.1 to 211.11.63.254211.11.63.25516,382
46211.11.64.0/18211.11.64.1 to 211.11.127.254211.11.127.25516,382
47211.11.128.0/18211.11.128.1 to 211.11.191.254211.11.191.25516,382
48211.11.192.0/18211.11.192.1 to 211.11.255.254211.11.255.25516,382
49211.12.0.0/18211.12.0.1 to 211.12.63.254211.12.63.25516,382
50211.12.64.0/18211.12.64.1 to 211.12.127.254211.12.127.25516,382
51211.12.128.0/18211.12.128.1 to 211.12.191.254211.12.191.25516,382
52211.12.192.0/18211.12.192.1 to 211.12.255.254211.12.255.25516,382
53211.13.0.0/18211.13.0.1 to 211.13.63.254211.13.63.25516,382
54211.13.64.0/18211.13.64.1 to 211.13.127.254211.13.127.25516,382
55211.13.128.0/18211.13.128.1 to 211.13.191.254211.13.191.25516,382
56211.13.192.0/18211.13.192.1 to 211.13.255.254211.13.255.25516,382
57211.14.0.0/18211.14.0.1 to 211.14.63.254211.14.63.25516,382
58211.14.64.0/18211.14.64.1 to 211.14.127.254211.14.127.25516,382
59211.14.128.0/18211.14.128.1 to 211.14.191.254211.14.191.25516,382
60211.14.192.0/18211.14.192.1 to 211.14.255.254211.14.255.25516,382
61211.15.0.0/18211.15.0.1 to 211.15.63.254211.15.63.25516,382
62211.15.64.0/18211.15.64.1 to 211.15.127.254211.15.127.25516,382
63211.15.128.0/18211.15.128.1 to 211.15.191.254211.15.191.25516,382
64211.15.192.0/18211.15.192.1 to 211.15.255.254211.15.255.25516,382
65211.16.0.0/18211.16.0.1 to 211.16.63.254211.16.63.25516,382
66211.16.64.0/18211.16.64.1 to 211.16.127.254211.16.127.25516,382
67211.16.128.0/18211.16.128.1 to 211.16.191.254211.16.191.25516,382
68211.16.192.0/18211.16.192.1 to 211.16.255.254211.16.255.25516,382
69211.17.0.0/18211.17.0.1 to 211.17.63.254211.17.63.25516,382
70211.17.64.0/18211.17.64.1 to 211.17.127.254211.17.127.25516,382
71211.17.128.0/18211.17.128.1 to 211.17.191.254211.17.191.25516,382
72211.17.192.0/18211.17.192.1 to 211.17.255.254211.17.255.25516,382
73211.18.0.0/18211.18.0.1 to 211.18.63.254211.18.63.25516,382
74211.18.64.0/18211.18.64.1 to 211.18.127.254211.18.127.25516,382
75211.18.128.0/18211.18.128.1 to 211.18.191.254211.18.191.25516,382
76211.18.192.0/18211.18.192.1 to 211.18.255.254211.18.255.25516,382
77211.19.0.0/18211.19.0.1 to 211.19.63.254211.19.63.25516,382
78211.19.64.0/18211.19.64.1 to 211.19.127.254211.19.127.25516,382
79211.19.128.0/18211.19.128.1 to 211.19.191.254211.19.191.25516,382
80211.19.192.0/18211.19.192.1 to 211.19.255.254211.19.255.25516,382
81211.20.0.0/18211.20.0.1 to 211.20.63.254211.20.63.25516,382
82211.20.64.0/18211.20.64.1 to 211.20.127.254211.20.127.25516,382
83211.20.128.0/18211.20.128.1 to 211.20.191.254211.20.191.25516,382
84211.20.192.0/18211.20.192.1 to 211.20.255.254211.20.255.25516,382
85211.21.0.0/18211.21.0.1 to 211.21.63.254211.21.63.25516,382
86211.21.64.0/18211.21.64.1 to 211.21.127.254211.21.127.25516,382
87211.21.128.0/18211.21.128.1 to 211.21.191.254211.21.191.25516,382
88211.21.192.0/18211.21.192.1 to 211.21.255.254211.21.255.25516,382
89211.22.0.0/18211.22.0.1 to 211.22.63.254211.22.63.25516,382
90211.22.64.0/18211.22.64.1 to 211.22.127.254211.22.127.25516,382
91211.22.128.0/18211.22.128.1 to 211.22.191.254211.22.191.25516,382
92211.22.192.0/18211.22.192.1 to 211.22.255.254211.22.255.25516,382
93211.23.0.0/18211.23.0.1 to 211.23.63.254211.23.63.25516,382
94211.23.64.0/18211.23.64.1 to 211.23.127.254211.23.127.25516,382
95211.23.128.0/18211.23.128.1 to 211.23.191.254211.23.191.25516,382
96211.23.192.0/18211.23.192.1 to 211.23.255.254211.23.255.25516,382
97211.24.0.0/18211.24.0.1 to 211.24.63.254211.24.63.25516,382
98211.24.64.0/18211.24.64.1 to 211.24.127.254211.24.127.25516,382
99211.24.128.0/18211.24.128.1 to 211.24.191.254211.24.191.25516,382
100211.24.192.0/18211.24.192.1 to 211.24.255.254211.24.255.25516,382
101211.25.0.0/18211.25.0.1 to 211.25.63.254211.25.63.25516,382
102211.25.64.0/18211.25.64.1 to 211.25.127.254211.25.127.25516,382
103211.25.128.0/18211.25.128.1 to 211.25.191.254211.25.191.25516,382
104211.25.192.0/18211.25.192.1 to 211.25.255.254211.25.255.25516,382
105211.26.0.0/18211.26.0.1 to 211.26.63.254211.26.63.25516,382
106211.26.64.0/18211.26.64.1 to 211.26.127.254211.26.127.25516,382
107211.26.128.0/18211.26.128.1 to 211.26.191.254211.26.191.25516,382
108211.26.192.0/18211.26.192.1 to 211.26.255.254211.26.255.25516,382
109211.27.0.0/18211.27.0.1 to 211.27.63.254211.27.63.25516,382
110211.27.64.0/18211.27.64.1 to 211.27.127.254211.27.127.25516,382
111211.27.128.0/18211.27.128.1 to 211.27.191.254211.27.191.25516,382
112211.27.192.0/18211.27.192.1 to 211.27.255.254211.27.255.25516,382
113211.28.0.0/18211.28.0.1 to 211.28.63.254211.28.63.25516,382
114211.28.64.0/18211.28.64.1 to 211.28.127.254211.28.127.25516,382
115211.28.128.0/18211.28.128.1 to 211.28.191.254211.28.191.25516,382
116211.28.192.0/18211.28.192.1 to 211.28.255.254211.28.255.25516,382
117211.29.0.0/18211.29.0.1 to 211.29.63.254211.29.63.25516,382
118211.29.64.0/18211.29.64.1 to 211.29.127.254211.29.127.25516,382
119211.29.128.0/18211.29.128.1 to 211.29.191.254211.29.191.25516,382
120211.29.192.0/18211.29.192.1 to 211.29.255.254211.29.255.25516,382
121211.30.0.0/18211.30.0.1 to 211.30.63.254211.30.63.25516,382
122211.30.64.0/18211.30.64.1 to 211.30.127.254211.30.127.25516,382
123211.30.128.0/18211.30.128.1 to 211.30.191.254211.30.191.25516,382
124211.30.192.0/18211.30.192.1 to 211.30.255.254211.30.255.25516,382
125211.31.0.0/18211.31.0.1 to 211.31.63.254211.31.63.25516,382
126211.31.64.0/18211.31.64.1 to 211.31.127.254211.31.127.25516,382
127211.31.128.0/18211.31.128.1 to 211.31.191.254211.31.191.25516,382
128211.31.192.0/18211.31.192.1 to 211.31.255.254211.31.255.25516,382
129211.32.0.0/18211.32.0.1 to 211.32.63.254211.32.63.25516,382
130211.32.64.0/18211.32.64.1 to 211.32.127.254211.32.127.25516,382
131211.32.128.0/18211.32.128.1 to 211.32.191.254211.32.191.25516,382
132211.32.192.0/18211.32.192.1 to 211.32.255.254211.32.255.25516,382
133211.33.0.0/18211.33.0.1 to 211.33.63.254211.33.63.25516,382
134211.33.64.0/18211.33.64.1 to 211.33.127.254211.33.127.25516,382
135211.33.128.0/18211.33.128.1 to 211.33.191.254211.33.191.25516,382
136211.33.192.0/18211.33.192.1 to 211.33.255.254211.33.255.25516,382
137211.34.0.0/18211.34.0.1 to 211.34.63.254211.34.63.25516,382
138211.34.64.0/18211.34.64.1 to 211.34.127.254211.34.127.25516,382
139211.34.128.0/18211.34.128.1 to 211.34.191.254211.34.191.25516,382
140211.34.192.0/18211.34.192.1 to 211.34.255.254211.34.255.25516,382
141211.35.0.0/18211.35.0.1 to 211.35.63.254211.35.63.25516,382
142211.35.64.0/18211.35.64.1 to 211.35.127.254211.35.127.25516,382
143211.35.128.0/18211.35.128.1 to 211.35.191.254211.35.191.25516,382
144211.35.192.0/18211.35.192.1 to 211.35.255.254211.35.255.25516,382
145211.36.0.0/18211.36.0.1 to 211.36.63.254211.36.63.25516,382
146211.36.64.0/18211.36.64.1 to 211.36.127.254211.36.127.25516,382
147211.36.128.0/18211.36.128.1 to 211.36.191.254211.36.191.25516,382
148211.36.192.0/18211.36.192.1 to 211.36.255.254211.36.255.25516,382
149211.37.0.0/18211.37.0.1 to 211.37.63.254211.37.63.25516,382
150211.37.64.0/18211.37.64.1 to 211.37.127.254211.37.127.25516,382
151211.37.128.0/18211.37.128.1 to 211.37.191.254211.37.191.25516,382
152211.37.192.0/18211.37.192.1 to 211.37.255.254211.37.255.25516,382
153211.38.0.0/18211.38.0.1 to 211.38.63.254211.38.63.25516,382
154211.38.64.0/18211.38.64.1 to 211.38.127.254211.38.127.25516,382
155211.38.128.0/18211.38.128.1 to 211.38.191.254211.38.191.25516,382
156211.38.192.0/18211.38.192.1 to 211.38.255.254211.38.255.25516,382
157211.39.0.0/18211.39.0.1 to 211.39.63.254211.39.63.25516,382
158211.39.64.0/18211.39.64.1 to 211.39.127.254211.39.127.25516,382
159211.39.128.0/18211.39.128.1 to 211.39.191.254211.39.191.25516,382
160211.39.192.0/18211.39.192.1 to 211.39.255.254211.39.255.25516,382
161211.40.0.0/18211.40.0.1 to 211.40.63.254211.40.63.25516,382
162211.40.64.0/18211.40.64.1 to 211.40.127.254211.40.127.25516,382
163211.40.128.0/18211.40.128.1 to 211.40.191.254211.40.191.25516,382
164211.40.192.0/18211.40.192.1 to 211.40.255.254211.40.255.25516,382
165211.41.0.0/18211.41.0.1 to 211.41.63.254211.41.63.25516,382
166211.41.64.0/18211.41.64.1 to 211.41.127.254211.41.127.25516,382
167211.41.128.0/18211.41.128.1 to 211.41.191.254211.41.191.25516,382
168211.41.192.0/18211.41.192.1 to 211.41.255.254211.41.255.25516,382
169211.42.0.0/18211.42.0.1 to 211.42.63.254211.42.63.25516,382
170211.42.64.0/18211.42.64.1 to 211.42.127.254211.42.127.25516,382
171211.42.128.0/18211.42.128.1 to 211.42.191.254211.42.191.25516,382
172211.42.192.0/18211.42.192.1 to 211.42.255.254211.42.255.25516,382
173211.43.0.0/18211.43.0.1 to 211.43.63.254211.43.63.25516,382
174211.43.64.0/18211.43.64.1 to 211.43.127.254211.43.127.25516,382
175211.43.128.0/18211.43.128.1 to 211.43.191.254211.43.191.25516,382
176211.43.192.0/18211.43.192.1 to 211.43.255.254211.43.255.25516,382
177211.44.0.0/18211.44.0.1 to 211.44.63.254211.44.63.25516,382
178211.44.64.0/18211.44.64.1 to 211.44.127.254211.44.127.25516,382
179211.44.128.0/18211.44.128.1 to 211.44.191.254211.44.191.25516,382
180211.44.192.0/18211.44.192.1 to 211.44.255.254211.44.255.25516,382
181211.45.0.0/18211.45.0.1 to 211.45.63.254211.45.63.25516,382
182211.45.64.0/18211.45.64.1 to 211.45.127.254211.45.127.25516,382
183211.45.128.0/18211.45.128.1 to 211.45.191.254211.45.191.25516,382
184211.45.192.0/18211.45.192.1 to 211.45.255.254211.45.255.25516,382
185211.46.0.0/18211.46.0.1 to 211.46.63.254211.46.63.25516,382
186211.46.64.0/18211.46.64.1 to 211.46.127.254211.46.127.25516,382
187211.46.128.0/18211.46.128.1 to 211.46.191.254211.46.191.25516,382
188211.46.192.0/18211.46.192.1 to 211.46.255.254211.46.255.25516,382
189211.47.0.0/18211.47.0.1 to 211.47.63.254211.47.63.25516,382
190211.47.64.0/18211.47.64.1 to 211.47.127.254211.47.127.25516,382
191211.47.128.0/18211.47.128.1 to 211.47.191.254211.47.191.25516,382
192211.47.192.0/18211.47.192.1 to 211.47.255.254211.47.255.25516,382
193211.48.0.0/18211.48.0.1 to 211.48.63.254211.48.63.25516,382
194211.48.64.0/18211.48.64.1 to 211.48.127.254211.48.127.25516,382
195211.48.128.0/18211.48.128.1 to 211.48.191.254211.48.191.25516,382
196211.48.192.0/18211.48.192.1 to 211.48.255.254211.48.255.25516,382
197211.49.0.0/18211.49.0.1 to 211.49.63.254211.49.63.25516,382
198211.49.64.0/18211.49.64.1 to 211.49.127.254211.49.127.25516,382
199211.49.128.0/18211.49.128.1 to 211.49.191.254211.49.191.25516,382
200211.49.192.0/18211.49.192.1 to 211.49.255.254211.49.255.25516,382
201211.50.0.0/18211.50.0.1 to 211.50.63.254211.50.63.25516,382
202211.50.64.0/18211.50.64.1 to 211.50.127.254211.50.127.25516,382
203211.50.128.0/18211.50.128.1 to 211.50.191.254211.50.191.25516,382
204211.50.192.0/18211.50.192.1 to 211.50.255.254211.50.255.25516,382
205211.51.0.0/18211.51.0.1 to 211.51.63.254211.51.63.25516,382
206211.51.64.0/18211.51.64.1 to 211.51.127.254211.51.127.25516,382
207211.51.128.0/18211.51.128.1 to 211.51.191.254211.51.191.25516,382
208211.51.192.0/18211.51.192.1 to 211.51.255.254211.51.255.25516,382
209211.52.0.0/18211.52.0.1 to 211.52.63.254211.52.63.25516,382
210211.52.64.0/18211.52.64.1 to 211.52.127.254211.52.127.25516,382
211211.52.128.0/18211.52.128.1 to 211.52.191.254211.52.191.25516,382
212211.52.192.0/18211.52.192.1 to 211.52.255.254211.52.255.25516,382
213211.53.0.0/18211.53.0.1 to 211.53.63.254211.53.63.25516,382
214211.53.64.0/18211.53.64.1 to 211.53.127.254211.53.127.25516,382
215211.53.128.0/18211.53.128.1 to 211.53.191.254211.53.191.25516,382
216211.53.192.0/18211.53.192.1 to 211.53.255.254211.53.255.25516,382
217211.54.0.0/18211.54.0.1 to 211.54.63.254211.54.63.25516,382
218211.54.64.0/18211.54.64.1 to 211.54.127.254211.54.127.25516,382
219211.54.128.0/18211.54.128.1 to 211.54.191.254211.54.191.25516,382
220211.54.192.0/18211.54.192.1 to 211.54.255.254211.54.255.25516,382
221211.55.0.0/18211.55.0.1 to 211.55.63.254211.55.63.25516,382
222211.55.64.0/18211.55.64.1 to 211.55.127.254211.55.127.25516,382
223211.55.128.0/18211.55.128.1 to 211.55.191.254211.55.191.25516,382
224211.55.192.0/18211.55.192.1 to 211.55.255.254211.55.255.25516,382
225211.56.0.0/18211.56.0.1 to 211.56.63.254211.56.63.25516,382
226211.56.64.0/18211.56.64.1 to 211.56.127.254211.56.127.25516,382
227211.56.128.0/18211.56.128.1 to 211.56.191.254211.56.191.25516,382
228211.56.192.0/18211.56.192.1 to 211.56.255.254211.56.255.25516,382
229211.57.0.0/18211.57.0.1 to 211.57.63.254211.57.63.25516,382
230211.57.64.0/18211.57.64.1 to 211.57.127.254211.57.127.25516,382
231211.57.128.0/18211.57.128.1 to 211.57.191.254211.57.191.25516,382
232211.57.192.0/18211.57.192.1 to 211.57.255.254211.57.255.25516,382
233211.58.0.0/18211.58.0.1 to 211.58.63.254211.58.63.25516,382
234211.58.64.0/18211.58.64.1 to 211.58.127.254211.58.127.25516,382
235211.58.128.0/18211.58.128.1 to 211.58.191.254211.58.191.25516,382
236211.58.192.0/18211.58.192.1 to 211.58.255.254211.58.255.25516,382
237211.59.0.0/18211.59.0.1 to 211.59.63.254211.59.63.25516,382
238211.59.64.0/18211.59.64.1 to 211.59.127.254211.59.127.25516,382
239211.59.128.0/18211.59.128.1 to 211.59.191.254211.59.191.25516,382
240211.59.192.0/18211.59.192.1 to 211.59.255.254211.59.255.25516,382
241211.60.0.0/18211.60.0.1 to 211.60.63.254211.60.63.25516,382
242211.60.64.0/18211.60.64.1 to 211.60.127.254211.60.127.25516,382
243211.60.128.0/18211.60.128.1 to 211.60.191.254211.60.191.25516,382
244211.60.192.0/18211.60.192.1 to 211.60.255.254211.60.255.25516,382
245211.61.0.0/18211.61.0.1 to 211.61.63.254211.61.63.25516,382
246211.61.64.0/18211.61.64.1 to 211.61.127.254211.61.127.25516,382
247211.61.128.0/18211.61.128.1 to 211.61.191.254211.61.191.25516,382
248211.61.192.0/18211.61.192.1 to 211.61.255.254211.61.255.25516,382
249211.62.0.0/18211.62.0.1 to 211.62.63.254211.62.63.25516,382
250211.62.64.0/18211.62.64.1 to 211.62.127.254211.62.127.25516,382
251211.62.128.0/18211.62.128.1 to 211.62.191.254211.62.191.25516,382
252211.62.192.0/18211.62.192.1 to 211.62.255.254211.62.255.25516,382
253211.63.0.0/18211.63.0.1 to 211.63.63.254211.63.63.25516,382
254211.63.64.0/18211.63.64.1 to 211.63.127.254211.63.127.25516,382
255211.63.128.0/18211.63.128.1 to 211.63.191.254211.63.191.25516,382
256211.63.192.0/18211.63.192.1 to 211.63.255.254211.63.255.25516,382

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.