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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.

Network212.78.0.0/17
Usable hosts32,766
Subnet mask255.255.128.0
Addresses32,768
Network address
212.78.0.0
Broadcast address
212.78.127.255
First usable
212.78.0.1
Last usable
212.78.127.254
Usable hosts
32,766 (32,768 less the network and broadcast addresses)
Subnet mask
255.255.128.0
Wildcard mask
0.0.127.255 (Cisco ACLs, OSPF)
Prefix length
/17
Type
Public public
Old class
C (default /24)
As numbers
Hex D44E0000 · Integer 3561881600 to 3561914367
Reverse DNS zones
0.78.212.in-addr.arpa
1.78.212.in-addr.arpa
2.78.212.in-addr.arpa
3.78.212.in-addr.arpa
4.78.212.in-addr.arpa
5.78.212.in-addr.arpa
6.78.212.in-addr.arpa
7.78.212.in-addr.arpa
8.78.212.in-addr.arpa
9.78.212.in-addr.arpa
10.78.212.in-addr.arpa
11.78.212.in-addr.arpa
12.78.212.in-addr.arpa
13.78.212.in-addr.arpa
14.78.212.in-addr.arpa
15.78.212.in-addr.arpa
and 112 more
/17 is not on a 8-bit boundary, so it takes 128 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11010100.01001110.00000000.00000000212.78.0.0
Subnet mask11111111.11111111.10000000.00000000255.255.128.0
Network11010100.01001110.00000000.00000000212.78.0.0
Broadcast11010100.01001110.01111111.11111111212.78.127.255
Split into smaller subnets/26
/18 (2)/19 (4)/20 (8)/21 (16)/22 (32)/23 (64)/24 (128)/25 (256)/26 (512)/27 (1,024)/28 (2,048)/29 (4,096)

212.78.0.0/17 makes 512 subnets of /26; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1212.78.0.0/26212.78.0.1 to 212.78.0.62212.78.0.6362
2212.78.0.64/26212.78.0.65 to 212.78.0.126212.78.0.12762
3212.78.0.128/26212.78.0.129 to 212.78.0.190212.78.0.19162
4212.78.0.192/26212.78.0.193 to 212.78.0.254212.78.0.25562
5212.78.1.0/26212.78.1.1 to 212.78.1.62212.78.1.6362
6212.78.1.64/26212.78.1.65 to 212.78.1.126212.78.1.12762
7212.78.1.128/26212.78.1.129 to 212.78.1.190212.78.1.19162
8212.78.1.192/26212.78.1.193 to 212.78.1.254212.78.1.25562
9212.78.2.0/26212.78.2.1 to 212.78.2.62212.78.2.6362
10212.78.2.64/26212.78.2.65 to 212.78.2.126212.78.2.12762
11212.78.2.128/26212.78.2.129 to 212.78.2.190212.78.2.19162
12212.78.2.192/26212.78.2.193 to 212.78.2.254212.78.2.25562
13212.78.3.0/26212.78.3.1 to 212.78.3.62212.78.3.6362
14212.78.3.64/26212.78.3.65 to 212.78.3.126212.78.3.12762
15212.78.3.128/26212.78.3.129 to 212.78.3.190212.78.3.19162
16212.78.3.192/26212.78.3.193 to 212.78.3.254212.78.3.25562
17212.78.4.0/26212.78.4.1 to 212.78.4.62212.78.4.6362
18212.78.4.64/26212.78.4.65 to 212.78.4.126212.78.4.12762
19212.78.4.128/26212.78.4.129 to 212.78.4.190212.78.4.19162
20212.78.4.192/26212.78.4.193 to 212.78.4.254212.78.4.25562
21212.78.5.0/26212.78.5.1 to 212.78.5.62212.78.5.6362
22212.78.5.64/26212.78.5.65 to 212.78.5.126212.78.5.12762
23212.78.5.128/26212.78.5.129 to 212.78.5.190212.78.5.19162
24212.78.5.192/26212.78.5.193 to 212.78.5.254212.78.5.25562
25212.78.6.0/26212.78.6.1 to 212.78.6.62212.78.6.6362
26212.78.6.64/26212.78.6.65 to 212.78.6.126212.78.6.12762
27212.78.6.128/26212.78.6.129 to 212.78.6.190212.78.6.19162
28212.78.6.192/26212.78.6.193 to 212.78.6.254212.78.6.25562
29212.78.7.0/26212.78.7.1 to 212.78.7.62212.78.7.6362
30212.78.7.64/26212.78.7.65 to 212.78.7.126212.78.7.12762
31212.78.7.128/26212.78.7.129 to 212.78.7.190212.78.7.19162
32212.78.7.192/26212.78.7.193 to 212.78.7.254212.78.7.25562
33212.78.8.0/26212.78.8.1 to 212.78.8.62212.78.8.6362
34212.78.8.64/26212.78.8.65 to 212.78.8.126212.78.8.12762
35212.78.8.128/26212.78.8.129 to 212.78.8.190212.78.8.19162
36212.78.8.192/26212.78.8.193 to 212.78.8.254212.78.8.25562
37212.78.9.0/26212.78.9.1 to 212.78.9.62212.78.9.6362
38212.78.9.64/26212.78.9.65 to 212.78.9.126212.78.9.12762
39212.78.9.128/26212.78.9.129 to 212.78.9.190212.78.9.19162
40212.78.9.192/26212.78.9.193 to 212.78.9.254212.78.9.25562
41212.78.10.0/26212.78.10.1 to 212.78.10.62212.78.10.6362
42212.78.10.64/26212.78.10.65 to 212.78.10.126212.78.10.12762
43212.78.10.128/26212.78.10.129 to 212.78.10.190212.78.10.19162
44212.78.10.192/26212.78.10.193 to 212.78.10.254212.78.10.25562
45212.78.11.0/26212.78.11.1 to 212.78.11.62212.78.11.6362
46212.78.11.64/26212.78.11.65 to 212.78.11.126212.78.11.12762
47212.78.11.128/26212.78.11.129 to 212.78.11.190212.78.11.19162
48212.78.11.192/26212.78.11.193 to 212.78.11.254212.78.11.25562
49212.78.12.0/26212.78.12.1 to 212.78.12.62212.78.12.6362
50212.78.12.64/26212.78.12.65 to 212.78.12.126212.78.12.12762
51212.78.12.128/26212.78.12.129 to 212.78.12.190212.78.12.19162
52212.78.12.192/26212.78.12.193 to 212.78.12.254212.78.12.25562
53212.78.13.0/26212.78.13.1 to 212.78.13.62212.78.13.6362
54212.78.13.64/26212.78.13.65 to 212.78.13.126212.78.13.12762
55212.78.13.128/26212.78.13.129 to 212.78.13.190212.78.13.19162
56212.78.13.192/26212.78.13.193 to 212.78.13.254212.78.13.25562
57212.78.14.0/26212.78.14.1 to 212.78.14.62212.78.14.6362
58212.78.14.64/26212.78.14.65 to 212.78.14.126212.78.14.12762
59212.78.14.128/26212.78.14.129 to 212.78.14.190212.78.14.19162
60212.78.14.192/26212.78.14.193 to 212.78.14.254212.78.14.25562
61212.78.15.0/26212.78.15.1 to 212.78.15.62212.78.15.6362
62212.78.15.64/26212.78.15.65 to 212.78.15.126212.78.15.12762
63212.78.15.128/26212.78.15.129 to 212.78.15.190212.78.15.19162
64212.78.15.192/26212.78.15.193 to 212.78.15.254212.78.15.25562
65212.78.16.0/26212.78.16.1 to 212.78.16.62212.78.16.6362
66212.78.16.64/26212.78.16.65 to 212.78.16.126212.78.16.12762
67212.78.16.128/26212.78.16.129 to 212.78.16.190212.78.16.19162
68212.78.16.192/26212.78.16.193 to 212.78.16.254212.78.16.25562
69212.78.17.0/26212.78.17.1 to 212.78.17.62212.78.17.6362
70212.78.17.64/26212.78.17.65 to 212.78.17.126212.78.17.12762
71212.78.17.128/26212.78.17.129 to 212.78.17.190212.78.17.19162
72212.78.17.192/26212.78.17.193 to 212.78.17.254212.78.17.25562
73212.78.18.0/26212.78.18.1 to 212.78.18.62212.78.18.6362
74212.78.18.64/26212.78.18.65 to 212.78.18.126212.78.18.12762
75212.78.18.128/26212.78.18.129 to 212.78.18.190212.78.18.19162
76212.78.18.192/26212.78.18.193 to 212.78.18.254212.78.18.25562
77212.78.19.0/26212.78.19.1 to 212.78.19.62212.78.19.6362
78212.78.19.64/26212.78.19.65 to 212.78.19.126212.78.19.12762
79212.78.19.128/26212.78.19.129 to 212.78.19.190212.78.19.19162
80212.78.19.192/26212.78.19.193 to 212.78.19.254212.78.19.25562
81212.78.20.0/26212.78.20.1 to 212.78.20.62212.78.20.6362
82212.78.20.64/26212.78.20.65 to 212.78.20.126212.78.20.12762
83212.78.20.128/26212.78.20.129 to 212.78.20.190212.78.20.19162
84212.78.20.192/26212.78.20.193 to 212.78.20.254212.78.20.25562
85212.78.21.0/26212.78.21.1 to 212.78.21.62212.78.21.6362
86212.78.21.64/26212.78.21.65 to 212.78.21.126212.78.21.12762
87212.78.21.128/26212.78.21.129 to 212.78.21.190212.78.21.19162
88212.78.21.192/26212.78.21.193 to 212.78.21.254212.78.21.25562
89212.78.22.0/26212.78.22.1 to 212.78.22.62212.78.22.6362
90212.78.22.64/26212.78.22.65 to 212.78.22.126212.78.22.12762
91212.78.22.128/26212.78.22.129 to 212.78.22.190212.78.22.19162
92212.78.22.192/26212.78.22.193 to 212.78.22.254212.78.22.25562
93212.78.23.0/26212.78.23.1 to 212.78.23.62212.78.23.6362
94212.78.23.64/26212.78.23.65 to 212.78.23.126212.78.23.12762
95212.78.23.128/26212.78.23.129 to 212.78.23.190212.78.23.19162
96212.78.23.192/26212.78.23.193 to 212.78.23.254212.78.23.25562
97212.78.24.0/26212.78.24.1 to 212.78.24.62212.78.24.6362
98212.78.24.64/26212.78.24.65 to 212.78.24.126212.78.24.12762
99212.78.24.128/26212.78.24.129 to 212.78.24.190212.78.24.19162
100212.78.24.192/26212.78.24.193 to 212.78.24.254212.78.24.25562
101212.78.25.0/26212.78.25.1 to 212.78.25.62212.78.25.6362
102212.78.25.64/26212.78.25.65 to 212.78.25.126212.78.25.12762
103212.78.25.128/26212.78.25.129 to 212.78.25.190212.78.25.19162
104212.78.25.192/26212.78.25.193 to 212.78.25.254212.78.25.25562
105212.78.26.0/26212.78.26.1 to 212.78.26.62212.78.26.6362
106212.78.26.64/26212.78.26.65 to 212.78.26.126212.78.26.12762
107212.78.26.128/26212.78.26.129 to 212.78.26.190212.78.26.19162
108212.78.26.192/26212.78.26.193 to 212.78.26.254212.78.26.25562
109212.78.27.0/26212.78.27.1 to 212.78.27.62212.78.27.6362
110212.78.27.64/26212.78.27.65 to 212.78.27.126212.78.27.12762
111212.78.27.128/26212.78.27.129 to 212.78.27.190212.78.27.19162
112212.78.27.192/26212.78.27.193 to 212.78.27.254212.78.27.25562
113212.78.28.0/26212.78.28.1 to 212.78.28.62212.78.28.6362
114212.78.28.64/26212.78.28.65 to 212.78.28.126212.78.28.12762
115212.78.28.128/26212.78.28.129 to 212.78.28.190212.78.28.19162
116212.78.28.192/26212.78.28.193 to 212.78.28.254212.78.28.25562
117212.78.29.0/26212.78.29.1 to 212.78.29.62212.78.29.6362
118212.78.29.64/26212.78.29.65 to 212.78.29.126212.78.29.12762
119212.78.29.128/26212.78.29.129 to 212.78.29.190212.78.29.19162
120212.78.29.192/26212.78.29.193 to 212.78.29.254212.78.29.25562
121212.78.30.0/26212.78.30.1 to 212.78.30.62212.78.30.6362
122212.78.30.64/26212.78.30.65 to 212.78.30.126212.78.30.12762
123212.78.30.128/26212.78.30.129 to 212.78.30.190212.78.30.19162
124212.78.30.192/26212.78.30.193 to 212.78.30.254212.78.30.25562
125212.78.31.0/26212.78.31.1 to 212.78.31.62212.78.31.6362
126212.78.31.64/26212.78.31.65 to 212.78.31.126212.78.31.12762
127212.78.31.128/26212.78.31.129 to 212.78.31.190212.78.31.19162
128212.78.31.192/26212.78.31.193 to 212.78.31.254212.78.31.25562
129212.78.32.0/26212.78.32.1 to 212.78.32.62212.78.32.6362
130212.78.32.64/26212.78.32.65 to 212.78.32.126212.78.32.12762
131212.78.32.128/26212.78.32.129 to 212.78.32.190212.78.32.19162
132212.78.32.192/26212.78.32.193 to 212.78.32.254212.78.32.25562
133212.78.33.0/26212.78.33.1 to 212.78.33.62212.78.33.6362
134212.78.33.64/26212.78.33.65 to 212.78.33.126212.78.33.12762
135212.78.33.128/26212.78.33.129 to 212.78.33.190212.78.33.19162
136212.78.33.192/26212.78.33.193 to 212.78.33.254212.78.33.25562
137212.78.34.0/26212.78.34.1 to 212.78.34.62212.78.34.6362
138212.78.34.64/26212.78.34.65 to 212.78.34.126212.78.34.12762
139212.78.34.128/26212.78.34.129 to 212.78.34.190212.78.34.19162
140212.78.34.192/26212.78.34.193 to 212.78.34.254212.78.34.25562
141212.78.35.0/26212.78.35.1 to 212.78.35.62212.78.35.6362
142212.78.35.64/26212.78.35.65 to 212.78.35.126212.78.35.12762
143212.78.35.128/26212.78.35.129 to 212.78.35.190212.78.35.19162
144212.78.35.192/26212.78.35.193 to 212.78.35.254212.78.35.25562
145212.78.36.0/26212.78.36.1 to 212.78.36.62212.78.36.6362
146212.78.36.64/26212.78.36.65 to 212.78.36.126212.78.36.12762
147212.78.36.128/26212.78.36.129 to 212.78.36.190212.78.36.19162
148212.78.36.192/26212.78.36.193 to 212.78.36.254212.78.36.25562
149212.78.37.0/26212.78.37.1 to 212.78.37.62212.78.37.6362
150212.78.37.64/26212.78.37.65 to 212.78.37.126212.78.37.12762
151212.78.37.128/26212.78.37.129 to 212.78.37.190212.78.37.19162
152212.78.37.192/26212.78.37.193 to 212.78.37.254212.78.37.25562
153212.78.38.0/26212.78.38.1 to 212.78.38.62212.78.38.6362
154212.78.38.64/26212.78.38.65 to 212.78.38.126212.78.38.12762
155212.78.38.128/26212.78.38.129 to 212.78.38.190212.78.38.19162
156212.78.38.192/26212.78.38.193 to 212.78.38.254212.78.38.25562
157212.78.39.0/26212.78.39.1 to 212.78.39.62212.78.39.6362
158212.78.39.64/26212.78.39.65 to 212.78.39.126212.78.39.12762
159212.78.39.128/26212.78.39.129 to 212.78.39.190212.78.39.19162
160212.78.39.192/26212.78.39.193 to 212.78.39.254212.78.39.25562
161212.78.40.0/26212.78.40.1 to 212.78.40.62212.78.40.6362
162212.78.40.64/26212.78.40.65 to 212.78.40.126212.78.40.12762
163212.78.40.128/26212.78.40.129 to 212.78.40.190212.78.40.19162
164212.78.40.192/26212.78.40.193 to 212.78.40.254212.78.40.25562
165212.78.41.0/26212.78.41.1 to 212.78.41.62212.78.41.6362
166212.78.41.64/26212.78.41.65 to 212.78.41.126212.78.41.12762
167212.78.41.128/26212.78.41.129 to 212.78.41.190212.78.41.19162
168212.78.41.192/26212.78.41.193 to 212.78.41.254212.78.41.25562
169212.78.42.0/26212.78.42.1 to 212.78.42.62212.78.42.6362
170212.78.42.64/26212.78.42.65 to 212.78.42.126212.78.42.12762
171212.78.42.128/26212.78.42.129 to 212.78.42.190212.78.42.19162
172212.78.42.192/26212.78.42.193 to 212.78.42.254212.78.42.25562
173212.78.43.0/26212.78.43.1 to 212.78.43.62212.78.43.6362
174212.78.43.64/26212.78.43.65 to 212.78.43.126212.78.43.12762
175212.78.43.128/26212.78.43.129 to 212.78.43.190212.78.43.19162
176212.78.43.192/26212.78.43.193 to 212.78.43.254212.78.43.25562
177212.78.44.0/26212.78.44.1 to 212.78.44.62212.78.44.6362
178212.78.44.64/26212.78.44.65 to 212.78.44.126212.78.44.12762
179212.78.44.128/26212.78.44.129 to 212.78.44.190212.78.44.19162
180212.78.44.192/26212.78.44.193 to 212.78.44.254212.78.44.25562
181212.78.45.0/26212.78.45.1 to 212.78.45.62212.78.45.6362
182212.78.45.64/26212.78.45.65 to 212.78.45.126212.78.45.12762
183212.78.45.128/26212.78.45.129 to 212.78.45.190212.78.45.19162
184212.78.45.192/26212.78.45.193 to 212.78.45.254212.78.45.25562
185212.78.46.0/26212.78.46.1 to 212.78.46.62212.78.46.6362
186212.78.46.64/26212.78.46.65 to 212.78.46.126212.78.46.12762
187212.78.46.128/26212.78.46.129 to 212.78.46.190212.78.46.19162
188212.78.46.192/26212.78.46.193 to 212.78.46.254212.78.46.25562
189212.78.47.0/26212.78.47.1 to 212.78.47.62212.78.47.6362
190212.78.47.64/26212.78.47.65 to 212.78.47.126212.78.47.12762
191212.78.47.128/26212.78.47.129 to 212.78.47.190212.78.47.19162
192212.78.47.192/26212.78.47.193 to 212.78.47.254212.78.47.25562
193212.78.48.0/26212.78.48.1 to 212.78.48.62212.78.48.6362
194212.78.48.64/26212.78.48.65 to 212.78.48.126212.78.48.12762
195212.78.48.128/26212.78.48.129 to 212.78.48.190212.78.48.19162
196212.78.48.192/26212.78.48.193 to 212.78.48.254212.78.48.25562
197212.78.49.0/26212.78.49.1 to 212.78.49.62212.78.49.6362
198212.78.49.64/26212.78.49.65 to 212.78.49.126212.78.49.12762
199212.78.49.128/26212.78.49.129 to 212.78.49.190212.78.49.19162
200212.78.49.192/26212.78.49.193 to 212.78.49.254212.78.49.25562
201212.78.50.0/26212.78.50.1 to 212.78.50.62212.78.50.6362
202212.78.50.64/26212.78.50.65 to 212.78.50.126212.78.50.12762
203212.78.50.128/26212.78.50.129 to 212.78.50.190212.78.50.19162
204212.78.50.192/26212.78.50.193 to 212.78.50.254212.78.50.25562
205212.78.51.0/26212.78.51.1 to 212.78.51.62212.78.51.6362
206212.78.51.64/26212.78.51.65 to 212.78.51.126212.78.51.12762
207212.78.51.128/26212.78.51.129 to 212.78.51.190212.78.51.19162
208212.78.51.192/26212.78.51.193 to 212.78.51.254212.78.51.25562
209212.78.52.0/26212.78.52.1 to 212.78.52.62212.78.52.6362
210212.78.52.64/26212.78.52.65 to 212.78.52.126212.78.52.12762
211212.78.52.128/26212.78.52.129 to 212.78.52.190212.78.52.19162
212212.78.52.192/26212.78.52.193 to 212.78.52.254212.78.52.25562
213212.78.53.0/26212.78.53.1 to 212.78.53.62212.78.53.6362
214212.78.53.64/26212.78.53.65 to 212.78.53.126212.78.53.12762
215212.78.53.128/26212.78.53.129 to 212.78.53.190212.78.53.19162
216212.78.53.192/26212.78.53.193 to 212.78.53.254212.78.53.25562
217212.78.54.0/26212.78.54.1 to 212.78.54.62212.78.54.6362
218212.78.54.64/26212.78.54.65 to 212.78.54.126212.78.54.12762
219212.78.54.128/26212.78.54.129 to 212.78.54.190212.78.54.19162
220212.78.54.192/26212.78.54.193 to 212.78.54.254212.78.54.25562
221212.78.55.0/26212.78.55.1 to 212.78.55.62212.78.55.6362
222212.78.55.64/26212.78.55.65 to 212.78.55.126212.78.55.12762
223212.78.55.128/26212.78.55.129 to 212.78.55.190212.78.55.19162
224212.78.55.192/26212.78.55.193 to 212.78.55.254212.78.55.25562
225212.78.56.0/26212.78.56.1 to 212.78.56.62212.78.56.6362
226212.78.56.64/26212.78.56.65 to 212.78.56.126212.78.56.12762
227212.78.56.128/26212.78.56.129 to 212.78.56.190212.78.56.19162
228212.78.56.192/26212.78.56.193 to 212.78.56.254212.78.56.25562
229212.78.57.0/26212.78.57.1 to 212.78.57.62212.78.57.6362
230212.78.57.64/26212.78.57.65 to 212.78.57.126212.78.57.12762
231212.78.57.128/26212.78.57.129 to 212.78.57.190212.78.57.19162
232212.78.57.192/26212.78.57.193 to 212.78.57.254212.78.57.25562
233212.78.58.0/26212.78.58.1 to 212.78.58.62212.78.58.6362
234212.78.58.64/26212.78.58.65 to 212.78.58.126212.78.58.12762
235212.78.58.128/26212.78.58.129 to 212.78.58.190212.78.58.19162
236212.78.58.192/26212.78.58.193 to 212.78.58.254212.78.58.25562
237212.78.59.0/26212.78.59.1 to 212.78.59.62212.78.59.6362
238212.78.59.64/26212.78.59.65 to 212.78.59.126212.78.59.12762
239212.78.59.128/26212.78.59.129 to 212.78.59.190212.78.59.19162
240212.78.59.192/26212.78.59.193 to 212.78.59.254212.78.59.25562
241212.78.60.0/26212.78.60.1 to 212.78.60.62212.78.60.6362
242212.78.60.64/26212.78.60.65 to 212.78.60.126212.78.60.12762
243212.78.60.128/26212.78.60.129 to 212.78.60.190212.78.60.19162
244212.78.60.192/26212.78.60.193 to 212.78.60.254212.78.60.25562
245212.78.61.0/26212.78.61.1 to 212.78.61.62212.78.61.6362
246212.78.61.64/26212.78.61.65 to 212.78.61.126212.78.61.12762
247212.78.61.128/26212.78.61.129 to 212.78.61.190212.78.61.19162
248212.78.61.192/26212.78.61.193 to 212.78.61.254212.78.61.25562
249212.78.62.0/26212.78.62.1 to 212.78.62.62212.78.62.6362
250212.78.62.64/26212.78.62.65 to 212.78.62.126212.78.62.12762
251212.78.62.128/26212.78.62.129 to 212.78.62.190212.78.62.19162
252212.78.62.192/26212.78.62.193 to 212.78.62.254212.78.62.25562
253212.78.63.0/26212.78.63.1 to 212.78.63.62212.78.63.6362
254212.78.63.64/26212.78.63.65 to 212.78.63.126212.78.63.12762
255212.78.63.128/26212.78.63.129 to 212.78.63.190212.78.63.19162
256212.78.63.192/26212.78.63.193 to 212.78.63.254212.78.63.25562

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.