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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.

Network138.0.0.0/10
Usable hosts4,194,302
Subnet mask255.192.0.0
Addresses4,194,304
Network address
138.0.0.0
Broadcast address
138.63.255.255
First usable
138.0.0.1
Last usable
138.63.255.254
Usable hosts
4,194,302 (4,194,304 less the network and broadcast addresses)
Subnet mask
255.192.0.0
Wildcard mask
0.63.255.255 (Cisco ACLs, OSPF)
Prefix length
/10
Type
Public public
Old class
B (default /16)
As numbers
Hex 8A000000 · Integer 2315255808 to 2319450111
Reverse DNS zones
0.138.in-addr.arpa
1.138.in-addr.arpa
2.138.in-addr.arpa
3.138.in-addr.arpa
4.138.in-addr.arpa
5.138.in-addr.arpa
6.138.in-addr.arpa
7.138.in-addr.arpa
8.138.in-addr.arpa
9.138.in-addr.arpa
10.138.in-addr.arpa
11.138.in-addr.arpa
12.138.in-addr.arpa
13.138.in-addr.arpa
14.138.in-addr.arpa
15.138.in-addr.arpa
and 48 more
/10 is not on a 8-bit boundary, so it takes 64 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10001010.00000000.00000000.00000000138.0.0.0
Subnet mask11111111.11000000.00000000.00000000255.192.0.0
Network10001010.00000000.00000000.00000000138.0.0.0
Broadcast10001010.00111111.11111111.11111111138.63.255.255
Split into smaller subnets/21
/11 (2)/12 (4)/13 (8)/14 (16)/15 (32)/16 (64)/17 (128)/18 (256)/19 (512)/20 (1,024)/21 (2,048)/22 (4,096)

138.0.0.0/10 makes 2,048 subnets of /21; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1138.0.0.0/21138.0.0.1 to 138.0.7.254138.0.7.2552,046
2138.0.8.0/21138.0.8.1 to 138.0.15.254138.0.15.2552,046
3138.0.16.0/21138.0.16.1 to 138.0.23.254138.0.23.2552,046
4138.0.24.0/21138.0.24.1 to 138.0.31.254138.0.31.2552,046
5138.0.32.0/21138.0.32.1 to 138.0.39.254138.0.39.2552,046
6138.0.40.0/21138.0.40.1 to 138.0.47.254138.0.47.2552,046
7138.0.48.0/21138.0.48.1 to 138.0.55.254138.0.55.2552,046
8138.0.56.0/21138.0.56.1 to 138.0.63.254138.0.63.2552,046
9138.0.64.0/21138.0.64.1 to 138.0.71.254138.0.71.2552,046
10138.0.72.0/21138.0.72.1 to 138.0.79.254138.0.79.2552,046
11138.0.80.0/21138.0.80.1 to 138.0.87.254138.0.87.2552,046
12138.0.88.0/21138.0.88.1 to 138.0.95.254138.0.95.2552,046
13138.0.96.0/21138.0.96.1 to 138.0.103.254138.0.103.2552,046
14138.0.104.0/21138.0.104.1 to 138.0.111.254138.0.111.2552,046
15138.0.112.0/21138.0.112.1 to 138.0.119.254138.0.119.2552,046
16138.0.120.0/21138.0.120.1 to 138.0.127.254138.0.127.2552,046
17138.0.128.0/21138.0.128.1 to 138.0.135.254138.0.135.2552,046
18138.0.136.0/21138.0.136.1 to 138.0.143.254138.0.143.2552,046
19138.0.144.0/21138.0.144.1 to 138.0.151.254138.0.151.2552,046
20138.0.152.0/21138.0.152.1 to 138.0.159.254138.0.159.2552,046
21138.0.160.0/21138.0.160.1 to 138.0.167.254138.0.167.2552,046
22138.0.168.0/21138.0.168.1 to 138.0.175.254138.0.175.2552,046
23138.0.176.0/21138.0.176.1 to 138.0.183.254138.0.183.2552,046
24138.0.184.0/21138.0.184.1 to 138.0.191.254138.0.191.2552,046
25138.0.192.0/21138.0.192.1 to 138.0.199.254138.0.199.2552,046
26138.0.200.0/21138.0.200.1 to 138.0.207.254138.0.207.2552,046
27138.0.208.0/21138.0.208.1 to 138.0.215.254138.0.215.2552,046
28138.0.216.0/21138.0.216.1 to 138.0.223.254138.0.223.2552,046
29138.0.224.0/21138.0.224.1 to 138.0.231.254138.0.231.2552,046
30138.0.232.0/21138.0.232.1 to 138.0.239.254138.0.239.2552,046
31138.0.240.0/21138.0.240.1 to 138.0.247.254138.0.247.2552,046
32138.0.248.0/21138.0.248.1 to 138.0.255.254138.0.255.2552,046
33138.1.0.0/21138.1.0.1 to 138.1.7.254138.1.7.2552,046
34138.1.8.0/21138.1.8.1 to 138.1.15.254138.1.15.2552,046
35138.1.16.0/21138.1.16.1 to 138.1.23.254138.1.23.2552,046
36138.1.24.0/21138.1.24.1 to 138.1.31.254138.1.31.2552,046
37138.1.32.0/21138.1.32.1 to 138.1.39.254138.1.39.2552,046
38138.1.40.0/21138.1.40.1 to 138.1.47.254138.1.47.2552,046
39138.1.48.0/21138.1.48.1 to 138.1.55.254138.1.55.2552,046
40138.1.56.0/21138.1.56.1 to 138.1.63.254138.1.63.2552,046
41138.1.64.0/21138.1.64.1 to 138.1.71.254138.1.71.2552,046
42138.1.72.0/21138.1.72.1 to 138.1.79.254138.1.79.2552,046
43138.1.80.0/21138.1.80.1 to 138.1.87.254138.1.87.2552,046
44138.1.88.0/21138.1.88.1 to 138.1.95.254138.1.95.2552,046
45138.1.96.0/21138.1.96.1 to 138.1.103.254138.1.103.2552,046
46138.1.104.0/21138.1.104.1 to 138.1.111.254138.1.111.2552,046
47138.1.112.0/21138.1.112.1 to 138.1.119.254138.1.119.2552,046
48138.1.120.0/21138.1.120.1 to 138.1.127.254138.1.127.2552,046
49138.1.128.0/21138.1.128.1 to 138.1.135.254138.1.135.2552,046
50138.1.136.0/21138.1.136.1 to 138.1.143.254138.1.143.2552,046
51138.1.144.0/21138.1.144.1 to 138.1.151.254138.1.151.2552,046
52138.1.152.0/21138.1.152.1 to 138.1.159.254138.1.159.2552,046
53138.1.160.0/21138.1.160.1 to 138.1.167.254138.1.167.2552,046
54138.1.168.0/21138.1.168.1 to 138.1.175.254138.1.175.2552,046
55138.1.176.0/21138.1.176.1 to 138.1.183.254138.1.183.2552,046
56138.1.184.0/21138.1.184.1 to 138.1.191.254138.1.191.2552,046
57138.1.192.0/21138.1.192.1 to 138.1.199.254138.1.199.2552,046
58138.1.200.0/21138.1.200.1 to 138.1.207.254138.1.207.2552,046
59138.1.208.0/21138.1.208.1 to 138.1.215.254138.1.215.2552,046
60138.1.216.0/21138.1.216.1 to 138.1.223.254138.1.223.2552,046
61138.1.224.0/21138.1.224.1 to 138.1.231.254138.1.231.2552,046
62138.1.232.0/21138.1.232.1 to 138.1.239.254138.1.239.2552,046
63138.1.240.0/21138.1.240.1 to 138.1.247.254138.1.247.2552,046
64138.1.248.0/21138.1.248.1 to 138.1.255.254138.1.255.2552,046
65138.2.0.0/21138.2.0.1 to 138.2.7.254138.2.7.2552,046
66138.2.8.0/21138.2.8.1 to 138.2.15.254138.2.15.2552,046
67138.2.16.0/21138.2.16.1 to 138.2.23.254138.2.23.2552,046
68138.2.24.0/21138.2.24.1 to 138.2.31.254138.2.31.2552,046
69138.2.32.0/21138.2.32.1 to 138.2.39.254138.2.39.2552,046
70138.2.40.0/21138.2.40.1 to 138.2.47.254138.2.47.2552,046
71138.2.48.0/21138.2.48.1 to 138.2.55.254138.2.55.2552,046
72138.2.56.0/21138.2.56.1 to 138.2.63.254138.2.63.2552,046
73138.2.64.0/21138.2.64.1 to 138.2.71.254138.2.71.2552,046
74138.2.72.0/21138.2.72.1 to 138.2.79.254138.2.79.2552,046
75138.2.80.0/21138.2.80.1 to 138.2.87.254138.2.87.2552,046
76138.2.88.0/21138.2.88.1 to 138.2.95.254138.2.95.2552,046
77138.2.96.0/21138.2.96.1 to 138.2.103.254138.2.103.2552,046
78138.2.104.0/21138.2.104.1 to 138.2.111.254138.2.111.2552,046
79138.2.112.0/21138.2.112.1 to 138.2.119.254138.2.119.2552,046
80138.2.120.0/21138.2.120.1 to 138.2.127.254138.2.127.2552,046
81138.2.128.0/21138.2.128.1 to 138.2.135.254138.2.135.2552,046
82138.2.136.0/21138.2.136.1 to 138.2.143.254138.2.143.2552,046
83138.2.144.0/21138.2.144.1 to 138.2.151.254138.2.151.2552,046
84138.2.152.0/21138.2.152.1 to 138.2.159.254138.2.159.2552,046
85138.2.160.0/21138.2.160.1 to 138.2.167.254138.2.167.2552,046
86138.2.168.0/21138.2.168.1 to 138.2.175.254138.2.175.2552,046
87138.2.176.0/21138.2.176.1 to 138.2.183.254138.2.183.2552,046
88138.2.184.0/21138.2.184.1 to 138.2.191.254138.2.191.2552,046
89138.2.192.0/21138.2.192.1 to 138.2.199.254138.2.199.2552,046
90138.2.200.0/21138.2.200.1 to 138.2.207.254138.2.207.2552,046
91138.2.208.0/21138.2.208.1 to 138.2.215.254138.2.215.2552,046
92138.2.216.0/21138.2.216.1 to 138.2.223.254138.2.223.2552,046
93138.2.224.0/21138.2.224.1 to 138.2.231.254138.2.231.2552,046
94138.2.232.0/21138.2.232.1 to 138.2.239.254138.2.239.2552,046
95138.2.240.0/21138.2.240.1 to 138.2.247.254138.2.247.2552,046
96138.2.248.0/21138.2.248.1 to 138.2.255.254138.2.255.2552,046
97138.3.0.0/21138.3.0.1 to 138.3.7.254138.3.7.2552,046
98138.3.8.0/21138.3.8.1 to 138.3.15.254138.3.15.2552,046
99138.3.16.0/21138.3.16.1 to 138.3.23.254138.3.23.2552,046
100138.3.24.0/21138.3.24.1 to 138.3.31.254138.3.31.2552,046
101138.3.32.0/21138.3.32.1 to 138.3.39.254138.3.39.2552,046
102138.3.40.0/21138.3.40.1 to 138.3.47.254138.3.47.2552,046
103138.3.48.0/21138.3.48.1 to 138.3.55.254138.3.55.2552,046
104138.3.56.0/21138.3.56.1 to 138.3.63.254138.3.63.2552,046
105138.3.64.0/21138.3.64.1 to 138.3.71.254138.3.71.2552,046
106138.3.72.0/21138.3.72.1 to 138.3.79.254138.3.79.2552,046
107138.3.80.0/21138.3.80.1 to 138.3.87.254138.3.87.2552,046
108138.3.88.0/21138.3.88.1 to 138.3.95.254138.3.95.2552,046
109138.3.96.0/21138.3.96.1 to 138.3.103.254138.3.103.2552,046
110138.3.104.0/21138.3.104.1 to 138.3.111.254138.3.111.2552,046
111138.3.112.0/21138.3.112.1 to 138.3.119.254138.3.119.2552,046
112138.3.120.0/21138.3.120.1 to 138.3.127.254138.3.127.2552,046
113138.3.128.0/21138.3.128.1 to 138.3.135.254138.3.135.2552,046
114138.3.136.0/21138.3.136.1 to 138.3.143.254138.3.143.2552,046
115138.3.144.0/21138.3.144.1 to 138.3.151.254138.3.151.2552,046
116138.3.152.0/21138.3.152.1 to 138.3.159.254138.3.159.2552,046
117138.3.160.0/21138.3.160.1 to 138.3.167.254138.3.167.2552,046
118138.3.168.0/21138.3.168.1 to 138.3.175.254138.3.175.2552,046
119138.3.176.0/21138.3.176.1 to 138.3.183.254138.3.183.2552,046
120138.3.184.0/21138.3.184.1 to 138.3.191.254138.3.191.2552,046
121138.3.192.0/21138.3.192.1 to 138.3.199.254138.3.199.2552,046
122138.3.200.0/21138.3.200.1 to 138.3.207.254138.3.207.2552,046
123138.3.208.0/21138.3.208.1 to 138.3.215.254138.3.215.2552,046
124138.3.216.0/21138.3.216.1 to 138.3.223.254138.3.223.2552,046
125138.3.224.0/21138.3.224.1 to 138.3.231.254138.3.231.2552,046
126138.3.232.0/21138.3.232.1 to 138.3.239.254138.3.239.2552,046
127138.3.240.0/21138.3.240.1 to 138.3.247.254138.3.247.2552,046
128138.3.248.0/21138.3.248.1 to 138.3.255.254138.3.255.2552,046
129138.4.0.0/21138.4.0.1 to 138.4.7.254138.4.7.2552,046
130138.4.8.0/21138.4.8.1 to 138.4.15.254138.4.15.2552,046
131138.4.16.0/21138.4.16.1 to 138.4.23.254138.4.23.2552,046
132138.4.24.0/21138.4.24.1 to 138.4.31.254138.4.31.2552,046
133138.4.32.0/21138.4.32.1 to 138.4.39.254138.4.39.2552,046
134138.4.40.0/21138.4.40.1 to 138.4.47.254138.4.47.2552,046
135138.4.48.0/21138.4.48.1 to 138.4.55.254138.4.55.2552,046
136138.4.56.0/21138.4.56.1 to 138.4.63.254138.4.63.2552,046
137138.4.64.0/21138.4.64.1 to 138.4.71.254138.4.71.2552,046
138138.4.72.0/21138.4.72.1 to 138.4.79.254138.4.79.2552,046
139138.4.80.0/21138.4.80.1 to 138.4.87.254138.4.87.2552,046
140138.4.88.0/21138.4.88.1 to 138.4.95.254138.4.95.2552,046
141138.4.96.0/21138.4.96.1 to 138.4.103.254138.4.103.2552,046
142138.4.104.0/21138.4.104.1 to 138.4.111.254138.4.111.2552,046
143138.4.112.0/21138.4.112.1 to 138.4.119.254138.4.119.2552,046
144138.4.120.0/21138.4.120.1 to 138.4.127.254138.4.127.2552,046
145138.4.128.0/21138.4.128.1 to 138.4.135.254138.4.135.2552,046
146138.4.136.0/21138.4.136.1 to 138.4.143.254138.4.143.2552,046
147138.4.144.0/21138.4.144.1 to 138.4.151.254138.4.151.2552,046
148138.4.152.0/21138.4.152.1 to 138.4.159.254138.4.159.2552,046
149138.4.160.0/21138.4.160.1 to 138.4.167.254138.4.167.2552,046
150138.4.168.0/21138.4.168.1 to 138.4.175.254138.4.175.2552,046
151138.4.176.0/21138.4.176.1 to 138.4.183.254138.4.183.2552,046
152138.4.184.0/21138.4.184.1 to 138.4.191.254138.4.191.2552,046
153138.4.192.0/21138.4.192.1 to 138.4.199.254138.4.199.2552,046
154138.4.200.0/21138.4.200.1 to 138.4.207.254138.4.207.2552,046
155138.4.208.0/21138.4.208.1 to 138.4.215.254138.4.215.2552,046
156138.4.216.0/21138.4.216.1 to 138.4.223.254138.4.223.2552,046
157138.4.224.0/21138.4.224.1 to 138.4.231.254138.4.231.2552,046
158138.4.232.0/21138.4.232.1 to 138.4.239.254138.4.239.2552,046
159138.4.240.0/21138.4.240.1 to 138.4.247.254138.4.247.2552,046
160138.4.248.0/21138.4.248.1 to 138.4.255.254138.4.255.2552,046
161138.5.0.0/21138.5.0.1 to 138.5.7.254138.5.7.2552,046
162138.5.8.0/21138.5.8.1 to 138.5.15.254138.5.15.2552,046
163138.5.16.0/21138.5.16.1 to 138.5.23.254138.5.23.2552,046
164138.5.24.0/21138.5.24.1 to 138.5.31.254138.5.31.2552,046
165138.5.32.0/21138.5.32.1 to 138.5.39.254138.5.39.2552,046
166138.5.40.0/21138.5.40.1 to 138.5.47.254138.5.47.2552,046
167138.5.48.0/21138.5.48.1 to 138.5.55.254138.5.55.2552,046
168138.5.56.0/21138.5.56.1 to 138.5.63.254138.5.63.2552,046
169138.5.64.0/21138.5.64.1 to 138.5.71.254138.5.71.2552,046
170138.5.72.0/21138.5.72.1 to 138.5.79.254138.5.79.2552,046
171138.5.80.0/21138.5.80.1 to 138.5.87.254138.5.87.2552,046
172138.5.88.0/21138.5.88.1 to 138.5.95.254138.5.95.2552,046
173138.5.96.0/21138.5.96.1 to 138.5.103.254138.5.103.2552,046
174138.5.104.0/21138.5.104.1 to 138.5.111.254138.5.111.2552,046
175138.5.112.0/21138.5.112.1 to 138.5.119.254138.5.119.2552,046
176138.5.120.0/21138.5.120.1 to 138.5.127.254138.5.127.2552,046
177138.5.128.0/21138.5.128.1 to 138.5.135.254138.5.135.2552,046
178138.5.136.0/21138.5.136.1 to 138.5.143.254138.5.143.2552,046
179138.5.144.0/21138.5.144.1 to 138.5.151.254138.5.151.2552,046
180138.5.152.0/21138.5.152.1 to 138.5.159.254138.5.159.2552,046
181138.5.160.0/21138.5.160.1 to 138.5.167.254138.5.167.2552,046
182138.5.168.0/21138.5.168.1 to 138.5.175.254138.5.175.2552,046
183138.5.176.0/21138.5.176.1 to 138.5.183.254138.5.183.2552,046
184138.5.184.0/21138.5.184.1 to 138.5.191.254138.5.191.2552,046
185138.5.192.0/21138.5.192.1 to 138.5.199.254138.5.199.2552,046
186138.5.200.0/21138.5.200.1 to 138.5.207.254138.5.207.2552,046
187138.5.208.0/21138.5.208.1 to 138.5.215.254138.5.215.2552,046
188138.5.216.0/21138.5.216.1 to 138.5.223.254138.5.223.2552,046
189138.5.224.0/21138.5.224.1 to 138.5.231.254138.5.231.2552,046
190138.5.232.0/21138.5.232.1 to 138.5.239.254138.5.239.2552,046
191138.5.240.0/21138.5.240.1 to 138.5.247.254138.5.247.2552,046
192138.5.248.0/21138.5.248.1 to 138.5.255.254138.5.255.2552,046
193138.6.0.0/21138.6.0.1 to 138.6.7.254138.6.7.2552,046
194138.6.8.0/21138.6.8.1 to 138.6.15.254138.6.15.2552,046
195138.6.16.0/21138.6.16.1 to 138.6.23.254138.6.23.2552,046
196138.6.24.0/21138.6.24.1 to 138.6.31.254138.6.31.2552,046
197138.6.32.0/21138.6.32.1 to 138.6.39.254138.6.39.2552,046
198138.6.40.0/21138.6.40.1 to 138.6.47.254138.6.47.2552,046
199138.6.48.0/21138.6.48.1 to 138.6.55.254138.6.55.2552,046
200138.6.56.0/21138.6.56.1 to 138.6.63.254138.6.63.2552,046
201138.6.64.0/21138.6.64.1 to 138.6.71.254138.6.71.2552,046
202138.6.72.0/21138.6.72.1 to 138.6.79.254138.6.79.2552,046
203138.6.80.0/21138.6.80.1 to 138.6.87.254138.6.87.2552,046
204138.6.88.0/21138.6.88.1 to 138.6.95.254138.6.95.2552,046
205138.6.96.0/21138.6.96.1 to 138.6.103.254138.6.103.2552,046
206138.6.104.0/21138.6.104.1 to 138.6.111.254138.6.111.2552,046
207138.6.112.0/21138.6.112.1 to 138.6.119.254138.6.119.2552,046
208138.6.120.0/21138.6.120.1 to 138.6.127.254138.6.127.2552,046
209138.6.128.0/21138.6.128.1 to 138.6.135.254138.6.135.2552,046
210138.6.136.0/21138.6.136.1 to 138.6.143.254138.6.143.2552,046
211138.6.144.0/21138.6.144.1 to 138.6.151.254138.6.151.2552,046
212138.6.152.0/21138.6.152.1 to 138.6.159.254138.6.159.2552,046
213138.6.160.0/21138.6.160.1 to 138.6.167.254138.6.167.2552,046
214138.6.168.0/21138.6.168.1 to 138.6.175.254138.6.175.2552,046
215138.6.176.0/21138.6.176.1 to 138.6.183.254138.6.183.2552,046
216138.6.184.0/21138.6.184.1 to 138.6.191.254138.6.191.2552,046
217138.6.192.0/21138.6.192.1 to 138.6.199.254138.6.199.2552,046
218138.6.200.0/21138.6.200.1 to 138.6.207.254138.6.207.2552,046
219138.6.208.0/21138.6.208.1 to 138.6.215.254138.6.215.2552,046
220138.6.216.0/21138.6.216.1 to 138.6.223.254138.6.223.2552,046
221138.6.224.0/21138.6.224.1 to 138.6.231.254138.6.231.2552,046
222138.6.232.0/21138.6.232.1 to 138.6.239.254138.6.239.2552,046
223138.6.240.0/21138.6.240.1 to 138.6.247.254138.6.247.2552,046
224138.6.248.0/21138.6.248.1 to 138.6.255.254138.6.255.2552,046
225138.7.0.0/21138.7.0.1 to 138.7.7.254138.7.7.2552,046
226138.7.8.0/21138.7.8.1 to 138.7.15.254138.7.15.2552,046
227138.7.16.0/21138.7.16.1 to 138.7.23.254138.7.23.2552,046
228138.7.24.0/21138.7.24.1 to 138.7.31.254138.7.31.2552,046
229138.7.32.0/21138.7.32.1 to 138.7.39.254138.7.39.2552,046
230138.7.40.0/21138.7.40.1 to 138.7.47.254138.7.47.2552,046
231138.7.48.0/21138.7.48.1 to 138.7.55.254138.7.55.2552,046
232138.7.56.0/21138.7.56.1 to 138.7.63.254138.7.63.2552,046
233138.7.64.0/21138.7.64.1 to 138.7.71.254138.7.71.2552,046
234138.7.72.0/21138.7.72.1 to 138.7.79.254138.7.79.2552,046
235138.7.80.0/21138.7.80.1 to 138.7.87.254138.7.87.2552,046
236138.7.88.0/21138.7.88.1 to 138.7.95.254138.7.95.2552,046
237138.7.96.0/21138.7.96.1 to 138.7.103.254138.7.103.2552,046
238138.7.104.0/21138.7.104.1 to 138.7.111.254138.7.111.2552,046
239138.7.112.0/21138.7.112.1 to 138.7.119.254138.7.119.2552,046
240138.7.120.0/21138.7.120.1 to 138.7.127.254138.7.127.2552,046
241138.7.128.0/21138.7.128.1 to 138.7.135.254138.7.135.2552,046
242138.7.136.0/21138.7.136.1 to 138.7.143.254138.7.143.2552,046
243138.7.144.0/21138.7.144.1 to 138.7.151.254138.7.151.2552,046
244138.7.152.0/21138.7.152.1 to 138.7.159.254138.7.159.2552,046
245138.7.160.0/21138.7.160.1 to 138.7.167.254138.7.167.2552,046
246138.7.168.0/21138.7.168.1 to 138.7.175.254138.7.175.2552,046
247138.7.176.0/21138.7.176.1 to 138.7.183.254138.7.183.2552,046
248138.7.184.0/21138.7.184.1 to 138.7.191.254138.7.191.2552,046
249138.7.192.0/21138.7.192.1 to 138.7.199.254138.7.199.2552,046
250138.7.200.0/21138.7.200.1 to 138.7.207.254138.7.207.2552,046
251138.7.208.0/21138.7.208.1 to 138.7.215.254138.7.215.2552,046
252138.7.216.0/21138.7.216.1 to 138.7.223.254138.7.223.2552,046
253138.7.224.0/21138.7.224.1 to 138.7.231.254138.7.231.2552,046
254138.7.232.0/21138.7.232.1 to 138.7.239.254138.7.239.2552,046
255138.7.240.0/21138.7.240.1 to 138.7.247.254138.7.247.2552,046
256138.7.248.0/21138.7.248.1 to 138.7.255.254138.7.255.2552,046

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.