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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.

Network205.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
205.0.0.0
Broadcast address
205.255.255.255
First usable
205.0.0.1
Last usable
205.255.255.254
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
C (default /24)
As numbers
Hex CD000000 · Integer 3439329280 to 3456106495
Reverse DNS zone
205.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11001101..00000000.00000000.00000000205.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network11001101..00000000.00000000.00000000205.0.0.0
Broadcast11001101..11111111.11111111.11111111205.255.255.255
Split into smaller subnets/18
/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)

205.0.0.0/8 makes 1,024 subnets of /18; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1205.0.0.0/18205.0.0.1 to 205.0.63.254205.0.63.25516,382
2205.0.64.0/18205.0.64.1 to 205.0.127.254205.0.127.25516,382
3205.0.128.0/18205.0.128.1 to 205.0.191.254205.0.191.25516,382
4205.0.192.0/18205.0.192.1 to 205.0.255.254205.0.255.25516,382
5205.1.0.0/18205.1.0.1 to 205.1.63.254205.1.63.25516,382
6205.1.64.0/18205.1.64.1 to 205.1.127.254205.1.127.25516,382
7205.1.128.0/18205.1.128.1 to 205.1.191.254205.1.191.25516,382
8205.1.192.0/18205.1.192.1 to 205.1.255.254205.1.255.25516,382
9205.2.0.0/18205.2.0.1 to 205.2.63.254205.2.63.25516,382
10205.2.64.0/18205.2.64.1 to 205.2.127.254205.2.127.25516,382
11205.2.128.0/18205.2.128.1 to 205.2.191.254205.2.191.25516,382
12205.2.192.0/18205.2.192.1 to 205.2.255.254205.2.255.25516,382
13205.3.0.0/18205.3.0.1 to 205.3.63.254205.3.63.25516,382
14205.3.64.0/18205.3.64.1 to 205.3.127.254205.3.127.25516,382
15205.3.128.0/18205.3.128.1 to 205.3.191.254205.3.191.25516,382
16205.3.192.0/18205.3.192.1 to 205.3.255.254205.3.255.25516,382
17205.4.0.0/18205.4.0.1 to 205.4.63.254205.4.63.25516,382
18205.4.64.0/18205.4.64.1 to 205.4.127.254205.4.127.25516,382
19205.4.128.0/18205.4.128.1 to 205.4.191.254205.4.191.25516,382
20205.4.192.0/18205.4.192.1 to 205.4.255.254205.4.255.25516,382
21205.5.0.0/18205.5.0.1 to 205.5.63.254205.5.63.25516,382
22205.5.64.0/18205.5.64.1 to 205.5.127.254205.5.127.25516,382
23205.5.128.0/18205.5.128.1 to 205.5.191.254205.5.191.25516,382
24205.5.192.0/18205.5.192.1 to 205.5.255.254205.5.255.25516,382
25205.6.0.0/18205.6.0.1 to 205.6.63.254205.6.63.25516,382
26205.6.64.0/18205.6.64.1 to 205.6.127.254205.6.127.25516,382
27205.6.128.0/18205.6.128.1 to 205.6.191.254205.6.191.25516,382
28205.6.192.0/18205.6.192.1 to 205.6.255.254205.6.255.25516,382
29205.7.0.0/18205.7.0.1 to 205.7.63.254205.7.63.25516,382
30205.7.64.0/18205.7.64.1 to 205.7.127.254205.7.127.25516,382
31205.7.128.0/18205.7.128.1 to 205.7.191.254205.7.191.25516,382
32205.7.192.0/18205.7.192.1 to 205.7.255.254205.7.255.25516,382
33205.8.0.0/18205.8.0.1 to 205.8.63.254205.8.63.25516,382
34205.8.64.0/18205.8.64.1 to 205.8.127.254205.8.127.25516,382
35205.8.128.0/18205.8.128.1 to 205.8.191.254205.8.191.25516,382
36205.8.192.0/18205.8.192.1 to 205.8.255.254205.8.255.25516,382
37205.9.0.0/18205.9.0.1 to 205.9.63.254205.9.63.25516,382
38205.9.64.0/18205.9.64.1 to 205.9.127.254205.9.127.25516,382
39205.9.128.0/18205.9.128.1 to 205.9.191.254205.9.191.25516,382
40205.9.192.0/18205.9.192.1 to 205.9.255.254205.9.255.25516,382
41205.10.0.0/18205.10.0.1 to 205.10.63.254205.10.63.25516,382
42205.10.64.0/18205.10.64.1 to 205.10.127.254205.10.127.25516,382
43205.10.128.0/18205.10.128.1 to 205.10.191.254205.10.191.25516,382
44205.10.192.0/18205.10.192.1 to 205.10.255.254205.10.255.25516,382
45205.11.0.0/18205.11.0.1 to 205.11.63.254205.11.63.25516,382
46205.11.64.0/18205.11.64.1 to 205.11.127.254205.11.127.25516,382
47205.11.128.0/18205.11.128.1 to 205.11.191.254205.11.191.25516,382
48205.11.192.0/18205.11.192.1 to 205.11.255.254205.11.255.25516,382
49205.12.0.0/18205.12.0.1 to 205.12.63.254205.12.63.25516,382
50205.12.64.0/18205.12.64.1 to 205.12.127.254205.12.127.25516,382
51205.12.128.0/18205.12.128.1 to 205.12.191.254205.12.191.25516,382
52205.12.192.0/18205.12.192.1 to 205.12.255.254205.12.255.25516,382
53205.13.0.0/18205.13.0.1 to 205.13.63.254205.13.63.25516,382
54205.13.64.0/18205.13.64.1 to 205.13.127.254205.13.127.25516,382
55205.13.128.0/18205.13.128.1 to 205.13.191.254205.13.191.25516,382
56205.13.192.0/18205.13.192.1 to 205.13.255.254205.13.255.25516,382
57205.14.0.0/18205.14.0.1 to 205.14.63.254205.14.63.25516,382
58205.14.64.0/18205.14.64.1 to 205.14.127.254205.14.127.25516,382
59205.14.128.0/18205.14.128.1 to 205.14.191.254205.14.191.25516,382
60205.14.192.0/18205.14.192.1 to 205.14.255.254205.14.255.25516,382
61205.15.0.0/18205.15.0.1 to 205.15.63.254205.15.63.25516,382
62205.15.64.0/18205.15.64.1 to 205.15.127.254205.15.127.25516,382
63205.15.128.0/18205.15.128.1 to 205.15.191.254205.15.191.25516,382
64205.15.192.0/18205.15.192.1 to 205.15.255.254205.15.255.25516,382
65205.16.0.0/18205.16.0.1 to 205.16.63.254205.16.63.25516,382
66205.16.64.0/18205.16.64.1 to 205.16.127.254205.16.127.25516,382
67205.16.128.0/18205.16.128.1 to 205.16.191.254205.16.191.25516,382
68205.16.192.0/18205.16.192.1 to 205.16.255.254205.16.255.25516,382
69205.17.0.0/18205.17.0.1 to 205.17.63.254205.17.63.25516,382
70205.17.64.0/18205.17.64.1 to 205.17.127.254205.17.127.25516,382
71205.17.128.0/18205.17.128.1 to 205.17.191.254205.17.191.25516,382
72205.17.192.0/18205.17.192.1 to 205.17.255.254205.17.255.25516,382
73205.18.0.0/18205.18.0.1 to 205.18.63.254205.18.63.25516,382
74205.18.64.0/18205.18.64.1 to 205.18.127.254205.18.127.25516,382
75205.18.128.0/18205.18.128.1 to 205.18.191.254205.18.191.25516,382
76205.18.192.0/18205.18.192.1 to 205.18.255.254205.18.255.25516,382
77205.19.0.0/18205.19.0.1 to 205.19.63.254205.19.63.25516,382
78205.19.64.0/18205.19.64.1 to 205.19.127.254205.19.127.25516,382
79205.19.128.0/18205.19.128.1 to 205.19.191.254205.19.191.25516,382
80205.19.192.0/18205.19.192.1 to 205.19.255.254205.19.255.25516,382
81205.20.0.0/18205.20.0.1 to 205.20.63.254205.20.63.25516,382
82205.20.64.0/18205.20.64.1 to 205.20.127.254205.20.127.25516,382
83205.20.128.0/18205.20.128.1 to 205.20.191.254205.20.191.25516,382
84205.20.192.0/18205.20.192.1 to 205.20.255.254205.20.255.25516,382
85205.21.0.0/18205.21.0.1 to 205.21.63.254205.21.63.25516,382
86205.21.64.0/18205.21.64.1 to 205.21.127.254205.21.127.25516,382
87205.21.128.0/18205.21.128.1 to 205.21.191.254205.21.191.25516,382
88205.21.192.0/18205.21.192.1 to 205.21.255.254205.21.255.25516,382
89205.22.0.0/18205.22.0.1 to 205.22.63.254205.22.63.25516,382
90205.22.64.0/18205.22.64.1 to 205.22.127.254205.22.127.25516,382
91205.22.128.0/18205.22.128.1 to 205.22.191.254205.22.191.25516,382
92205.22.192.0/18205.22.192.1 to 205.22.255.254205.22.255.25516,382
93205.23.0.0/18205.23.0.1 to 205.23.63.254205.23.63.25516,382
94205.23.64.0/18205.23.64.1 to 205.23.127.254205.23.127.25516,382
95205.23.128.0/18205.23.128.1 to 205.23.191.254205.23.191.25516,382
96205.23.192.0/18205.23.192.1 to 205.23.255.254205.23.255.25516,382
97205.24.0.0/18205.24.0.1 to 205.24.63.254205.24.63.25516,382
98205.24.64.0/18205.24.64.1 to 205.24.127.254205.24.127.25516,382
99205.24.128.0/18205.24.128.1 to 205.24.191.254205.24.191.25516,382
100205.24.192.0/18205.24.192.1 to 205.24.255.254205.24.255.25516,382
101205.25.0.0/18205.25.0.1 to 205.25.63.254205.25.63.25516,382
102205.25.64.0/18205.25.64.1 to 205.25.127.254205.25.127.25516,382
103205.25.128.0/18205.25.128.1 to 205.25.191.254205.25.191.25516,382
104205.25.192.0/18205.25.192.1 to 205.25.255.254205.25.255.25516,382
105205.26.0.0/18205.26.0.1 to 205.26.63.254205.26.63.25516,382
106205.26.64.0/18205.26.64.1 to 205.26.127.254205.26.127.25516,382
107205.26.128.0/18205.26.128.1 to 205.26.191.254205.26.191.25516,382
108205.26.192.0/18205.26.192.1 to 205.26.255.254205.26.255.25516,382
109205.27.0.0/18205.27.0.1 to 205.27.63.254205.27.63.25516,382
110205.27.64.0/18205.27.64.1 to 205.27.127.254205.27.127.25516,382
111205.27.128.0/18205.27.128.1 to 205.27.191.254205.27.191.25516,382
112205.27.192.0/18205.27.192.1 to 205.27.255.254205.27.255.25516,382
113205.28.0.0/18205.28.0.1 to 205.28.63.254205.28.63.25516,382
114205.28.64.0/18205.28.64.1 to 205.28.127.254205.28.127.25516,382
115205.28.128.0/18205.28.128.1 to 205.28.191.254205.28.191.25516,382
116205.28.192.0/18205.28.192.1 to 205.28.255.254205.28.255.25516,382
117205.29.0.0/18205.29.0.1 to 205.29.63.254205.29.63.25516,382
118205.29.64.0/18205.29.64.1 to 205.29.127.254205.29.127.25516,382
119205.29.128.0/18205.29.128.1 to 205.29.191.254205.29.191.25516,382
120205.29.192.0/18205.29.192.1 to 205.29.255.254205.29.255.25516,382
121205.30.0.0/18205.30.0.1 to 205.30.63.254205.30.63.25516,382
122205.30.64.0/18205.30.64.1 to 205.30.127.254205.30.127.25516,382
123205.30.128.0/18205.30.128.1 to 205.30.191.254205.30.191.25516,382
124205.30.192.0/18205.30.192.1 to 205.30.255.254205.30.255.25516,382
125205.31.0.0/18205.31.0.1 to 205.31.63.254205.31.63.25516,382
126205.31.64.0/18205.31.64.1 to 205.31.127.254205.31.127.25516,382
127205.31.128.0/18205.31.128.1 to 205.31.191.254205.31.191.25516,382
128205.31.192.0/18205.31.192.1 to 205.31.255.254205.31.255.25516,382
129205.32.0.0/18205.32.0.1 to 205.32.63.254205.32.63.25516,382
130205.32.64.0/18205.32.64.1 to 205.32.127.254205.32.127.25516,382
131205.32.128.0/18205.32.128.1 to 205.32.191.254205.32.191.25516,382
132205.32.192.0/18205.32.192.1 to 205.32.255.254205.32.255.25516,382
133205.33.0.0/18205.33.0.1 to 205.33.63.254205.33.63.25516,382
134205.33.64.0/18205.33.64.1 to 205.33.127.254205.33.127.25516,382
135205.33.128.0/18205.33.128.1 to 205.33.191.254205.33.191.25516,382
136205.33.192.0/18205.33.192.1 to 205.33.255.254205.33.255.25516,382
137205.34.0.0/18205.34.0.1 to 205.34.63.254205.34.63.25516,382
138205.34.64.0/18205.34.64.1 to 205.34.127.254205.34.127.25516,382
139205.34.128.0/18205.34.128.1 to 205.34.191.254205.34.191.25516,382
140205.34.192.0/18205.34.192.1 to 205.34.255.254205.34.255.25516,382
141205.35.0.0/18205.35.0.1 to 205.35.63.254205.35.63.25516,382
142205.35.64.0/18205.35.64.1 to 205.35.127.254205.35.127.25516,382
143205.35.128.0/18205.35.128.1 to 205.35.191.254205.35.191.25516,382
144205.35.192.0/18205.35.192.1 to 205.35.255.254205.35.255.25516,382
145205.36.0.0/18205.36.0.1 to 205.36.63.254205.36.63.25516,382
146205.36.64.0/18205.36.64.1 to 205.36.127.254205.36.127.25516,382
147205.36.128.0/18205.36.128.1 to 205.36.191.254205.36.191.25516,382
148205.36.192.0/18205.36.192.1 to 205.36.255.254205.36.255.25516,382
149205.37.0.0/18205.37.0.1 to 205.37.63.254205.37.63.25516,382
150205.37.64.0/18205.37.64.1 to 205.37.127.254205.37.127.25516,382
151205.37.128.0/18205.37.128.1 to 205.37.191.254205.37.191.25516,382
152205.37.192.0/18205.37.192.1 to 205.37.255.254205.37.255.25516,382
153205.38.0.0/18205.38.0.1 to 205.38.63.254205.38.63.25516,382
154205.38.64.0/18205.38.64.1 to 205.38.127.254205.38.127.25516,382
155205.38.128.0/18205.38.128.1 to 205.38.191.254205.38.191.25516,382
156205.38.192.0/18205.38.192.1 to 205.38.255.254205.38.255.25516,382
157205.39.0.0/18205.39.0.1 to 205.39.63.254205.39.63.25516,382
158205.39.64.0/18205.39.64.1 to 205.39.127.254205.39.127.25516,382
159205.39.128.0/18205.39.128.1 to 205.39.191.254205.39.191.25516,382
160205.39.192.0/18205.39.192.1 to 205.39.255.254205.39.255.25516,382
161205.40.0.0/18205.40.0.1 to 205.40.63.254205.40.63.25516,382
162205.40.64.0/18205.40.64.1 to 205.40.127.254205.40.127.25516,382
163205.40.128.0/18205.40.128.1 to 205.40.191.254205.40.191.25516,382
164205.40.192.0/18205.40.192.1 to 205.40.255.254205.40.255.25516,382
165205.41.0.0/18205.41.0.1 to 205.41.63.254205.41.63.25516,382
166205.41.64.0/18205.41.64.1 to 205.41.127.254205.41.127.25516,382
167205.41.128.0/18205.41.128.1 to 205.41.191.254205.41.191.25516,382
168205.41.192.0/18205.41.192.1 to 205.41.255.254205.41.255.25516,382
169205.42.0.0/18205.42.0.1 to 205.42.63.254205.42.63.25516,382
170205.42.64.0/18205.42.64.1 to 205.42.127.254205.42.127.25516,382
171205.42.128.0/18205.42.128.1 to 205.42.191.254205.42.191.25516,382
172205.42.192.0/18205.42.192.1 to 205.42.255.254205.42.255.25516,382
173205.43.0.0/18205.43.0.1 to 205.43.63.254205.43.63.25516,382
174205.43.64.0/18205.43.64.1 to 205.43.127.254205.43.127.25516,382
175205.43.128.0/18205.43.128.1 to 205.43.191.254205.43.191.25516,382
176205.43.192.0/18205.43.192.1 to 205.43.255.254205.43.255.25516,382
177205.44.0.0/18205.44.0.1 to 205.44.63.254205.44.63.25516,382
178205.44.64.0/18205.44.64.1 to 205.44.127.254205.44.127.25516,382
179205.44.128.0/18205.44.128.1 to 205.44.191.254205.44.191.25516,382
180205.44.192.0/18205.44.192.1 to 205.44.255.254205.44.255.25516,382
181205.45.0.0/18205.45.0.1 to 205.45.63.254205.45.63.25516,382
182205.45.64.0/18205.45.64.1 to 205.45.127.254205.45.127.25516,382
183205.45.128.0/18205.45.128.1 to 205.45.191.254205.45.191.25516,382
184205.45.192.0/18205.45.192.1 to 205.45.255.254205.45.255.25516,382
185205.46.0.0/18205.46.0.1 to 205.46.63.254205.46.63.25516,382
186205.46.64.0/18205.46.64.1 to 205.46.127.254205.46.127.25516,382
187205.46.128.0/18205.46.128.1 to 205.46.191.254205.46.191.25516,382
188205.46.192.0/18205.46.192.1 to 205.46.255.254205.46.255.25516,382
189205.47.0.0/18205.47.0.1 to 205.47.63.254205.47.63.25516,382
190205.47.64.0/18205.47.64.1 to 205.47.127.254205.47.127.25516,382
191205.47.128.0/18205.47.128.1 to 205.47.191.254205.47.191.25516,382
192205.47.192.0/18205.47.192.1 to 205.47.255.254205.47.255.25516,382
193205.48.0.0/18205.48.0.1 to 205.48.63.254205.48.63.25516,382
194205.48.64.0/18205.48.64.1 to 205.48.127.254205.48.127.25516,382
195205.48.128.0/18205.48.128.1 to 205.48.191.254205.48.191.25516,382
196205.48.192.0/18205.48.192.1 to 205.48.255.254205.48.255.25516,382
197205.49.0.0/18205.49.0.1 to 205.49.63.254205.49.63.25516,382
198205.49.64.0/18205.49.64.1 to 205.49.127.254205.49.127.25516,382
199205.49.128.0/18205.49.128.1 to 205.49.191.254205.49.191.25516,382
200205.49.192.0/18205.49.192.1 to 205.49.255.254205.49.255.25516,382
201205.50.0.0/18205.50.0.1 to 205.50.63.254205.50.63.25516,382
202205.50.64.0/18205.50.64.1 to 205.50.127.254205.50.127.25516,382
203205.50.128.0/18205.50.128.1 to 205.50.191.254205.50.191.25516,382
204205.50.192.0/18205.50.192.1 to 205.50.255.254205.50.255.25516,382
205205.51.0.0/18205.51.0.1 to 205.51.63.254205.51.63.25516,382
206205.51.64.0/18205.51.64.1 to 205.51.127.254205.51.127.25516,382
207205.51.128.0/18205.51.128.1 to 205.51.191.254205.51.191.25516,382
208205.51.192.0/18205.51.192.1 to 205.51.255.254205.51.255.25516,382
209205.52.0.0/18205.52.0.1 to 205.52.63.254205.52.63.25516,382
210205.52.64.0/18205.52.64.1 to 205.52.127.254205.52.127.25516,382
211205.52.128.0/18205.52.128.1 to 205.52.191.254205.52.191.25516,382
212205.52.192.0/18205.52.192.1 to 205.52.255.254205.52.255.25516,382
213205.53.0.0/18205.53.0.1 to 205.53.63.254205.53.63.25516,382
214205.53.64.0/18205.53.64.1 to 205.53.127.254205.53.127.25516,382
215205.53.128.0/18205.53.128.1 to 205.53.191.254205.53.191.25516,382
216205.53.192.0/18205.53.192.1 to 205.53.255.254205.53.255.25516,382
217205.54.0.0/18205.54.0.1 to 205.54.63.254205.54.63.25516,382
218205.54.64.0/18205.54.64.1 to 205.54.127.254205.54.127.25516,382
219205.54.128.0/18205.54.128.1 to 205.54.191.254205.54.191.25516,382
220205.54.192.0/18205.54.192.1 to 205.54.255.254205.54.255.25516,382
221205.55.0.0/18205.55.0.1 to 205.55.63.254205.55.63.25516,382
222205.55.64.0/18205.55.64.1 to 205.55.127.254205.55.127.25516,382
223205.55.128.0/18205.55.128.1 to 205.55.191.254205.55.191.25516,382
224205.55.192.0/18205.55.192.1 to 205.55.255.254205.55.255.25516,382
225205.56.0.0/18205.56.0.1 to 205.56.63.254205.56.63.25516,382
226205.56.64.0/18205.56.64.1 to 205.56.127.254205.56.127.25516,382
227205.56.128.0/18205.56.128.1 to 205.56.191.254205.56.191.25516,382
228205.56.192.0/18205.56.192.1 to 205.56.255.254205.56.255.25516,382
229205.57.0.0/18205.57.0.1 to 205.57.63.254205.57.63.25516,382
230205.57.64.0/18205.57.64.1 to 205.57.127.254205.57.127.25516,382
231205.57.128.0/18205.57.128.1 to 205.57.191.254205.57.191.25516,382
232205.57.192.0/18205.57.192.1 to 205.57.255.254205.57.255.25516,382
233205.58.0.0/18205.58.0.1 to 205.58.63.254205.58.63.25516,382
234205.58.64.0/18205.58.64.1 to 205.58.127.254205.58.127.25516,382
235205.58.128.0/18205.58.128.1 to 205.58.191.254205.58.191.25516,382
236205.58.192.0/18205.58.192.1 to 205.58.255.254205.58.255.25516,382
237205.59.0.0/18205.59.0.1 to 205.59.63.254205.59.63.25516,382
238205.59.64.0/18205.59.64.1 to 205.59.127.254205.59.127.25516,382
239205.59.128.0/18205.59.128.1 to 205.59.191.254205.59.191.25516,382
240205.59.192.0/18205.59.192.1 to 205.59.255.254205.59.255.25516,382
241205.60.0.0/18205.60.0.1 to 205.60.63.254205.60.63.25516,382
242205.60.64.0/18205.60.64.1 to 205.60.127.254205.60.127.25516,382
243205.60.128.0/18205.60.128.1 to 205.60.191.254205.60.191.25516,382
244205.60.192.0/18205.60.192.1 to 205.60.255.254205.60.255.25516,382
245205.61.0.0/18205.61.0.1 to 205.61.63.254205.61.63.25516,382
246205.61.64.0/18205.61.64.1 to 205.61.127.254205.61.127.25516,382
247205.61.128.0/18205.61.128.1 to 205.61.191.254205.61.191.25516,382
248205.61.192.0/18205.61.192.1 to 205.61.255.254205.61.255.25516,382
249205.62.0.0/18205.62.0.1 to 205.62.63.254205.62.63.25516,382
250205.62.64.0/18205.62.64.1 to 205.62.127.254205.62.127.25516,382
251205.62.128.0/18205.62.128.1 to 205.62.191.254205.62.191.25516,382
252205.62.192.0/18205.62.192.1 to 205.62.255.254205.62.255.25516,382
253205.63.0.0/18205.63.0.1 to 205.63.63.254205.63.63.25516,382
254205.63.64.0/18205.63.64.1 to 205.63.127.254205.63.127.25516,382
255205.63.128.0/18205.63.128.1 to 205.63.191.254205.63.191.25516,382
256205.63.192.0/18205.63.192.1 to 205.63.255.254205.63.255.25516,382

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.