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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.

Network138.0.0.0/7
Usable hosts33,554,430
Subnet mask254.0.0.0
Addresses33,554,432
Network address
138.0.0.0
Broadcast address
139.255.255.255
First usable
138.0.0.1
Last usable
139.255.255.254
Usable hosts
33,554,430 (33,554,432 less the network and broadcast addresses)
Subnet mask
254.0.0.0
Wildcard mask
1.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/7
Type
Public public
Old class
B (default /16)
As numbers
Hex 8A000000 · Integer 2315255808 to 2348810239
Reverse DNS zones
138.in-addr.arpa
139.in-addr.arpa
/7 is not on a 8-bit boundary, so it takes 2 /8 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10001010.00000000.00000000.00000000138.0.0.0
Subnet mask11111110.00000000.00000000.00000000254.0.0.0
Network10001010.00000000.00000000.00000000138.0.0.0
Broadcast10001011.11111111.11111111.11111111139.255.255.255
Split into smaller subnets/16
/8 (2)/9 (4)/10 (8)/11 (16)/12 (32)/13 (64)/14 (128)/15 (256)/16 (512)/17 (1,024)/18 (2,048)/19 (4,096)

138.0.0.0/7 makes 512 subnets of /16; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1138.0.0.0/16138.0.0.1 to 138.0.255.254138.0.255.25565,534
2138.1.0.0/16138.1.0.1 to 138.1.255.254138.1.255.25565,534
3138.2.0.0/16138.2.0.1 to 138.2.255.254138.2.255.25565,534
4138.3.0.0/16138.3.0.1 to 138.3.255.254138.3.255.25565,534
5138.4.0.0/16138.4.0.1 to 138.4.255.254138.4.255.25565,534
6138.5.0.0/16138.5.0.1 to 138.5.255.254138.5.255.25565,534
7138.6.0.0/16138.6.0.1 to 138.6.255.254138.6.255.25565,534
8138.7.0.0/16138.7.0.1 to 138.7.255.254138.7.255.25565,534
9138.8.0.0/16138.8.0.1 to 138.8.255.254138.8.255.25565,534
10138.9.0.0/16138.9.0.1 to 138.9.255.254138.9.255.25565,534
11138.10.0.0/16138.10.0.1 to 138.10.255.254138.10.255.25565,534
12138.11.0.0/16138.11.0.1 to 138.11.255.254138.11.255.25565,534
13138.12.0.0/16138.12.0.1 to 138.12.255.254138.12.255.25565,534
14138.13.0.0/16138.13.0.1 to 138.13.255.254138.13.255.25565,534
15138.14.0.0/16138.14.0.1 to 138.14.255.254138.14.255.25565,534
16138.15.0.0/16138.15.0.1 to 138.15.255.254138.15.255.25565,534
17138.16.0.0/16138.16.0.1 to 138.16.255.254138.16.255.25565,534
18138.17.0.0/16138.17.0.1 to 138.17.255.254138.17.255.25565,534
19138.18.0.0/16138.18.0.1 to 138.18.255.254138.18.255.25565,534
20138.19.0.0/16138.19.0.1 to 138.19.255.254138.19.255.25565,534
21138.20.0.0/16138.20.0.1 to 138.20.255.254138.20.255.25565,534
22138.21.0.0/16138.21.0.1 to 138.21.255.254138.21.255.25565,534
23138.22.0.0/16138.22.0.1 to 138.22.255.254138.22.255.25565,534
24138.23.0.0/16138.23.0.1 to 138.23.255.254138.23.255.25565,534
25138.24.0.0/16138.24.0.1 to 138.24.255.254138.24.255.25565,534
26138.25.0.0/16138.25.0.1 to 138.25.255.254138.25.255.25565,534
27138.26.0.0/16138.26.0.1 to 138.26.255.254138.26.255.25565,534
28138.27.0.0/16138.27.0.1 to 138.27.255.254138.27.255.25565,534
29138.28.0.0/16138.28.0.1 to 138.28.255.254138.28.255.25565,534
30138.29.0.0/16138.29.0.1 to 138.29.255.254138.29.255.25565,534
31138.30.0.0/16138.30.0.1 to 138.30.255.254138.30.255.25565,534
32138.31.0.0/16138.31.0.1 to 138.31.255.254138.31.255.25565,534
33138.32.0.0/16138.32.0.1 to 138.32.255.254138.32.255.25565,534
34138.33.0.0/16138.33.0.1 to 138.33.255.254138.33.255.25565,534
35138.34.0.0/16138.34.0.1 to 138.34.255.254138.34.255.25565,534
36138.35.0.0/16138.35.0.1 to 138.35.255.254138.35.255.25565,534
37138.36.0.0/16138.36.0.1 to 138.36.255.254138.36.255.25565,534
38138.37.0.0/16138.37.0.1 to 138.37.255.254138.37.255.25565,534
39138.38.0.0/16138.38.0.1 to 138.38.255.254138.38.255.25565,534
40138.39.0.0/16138.39.0.1 to 138.39.255.254138.39.255.25565,534
41138.40.0.0/16138.40.0.1 to 138.40.255.254138.40.255.25565,534
42138.41.0.0/16138.41.0.1 to 138.41.255.254138.41.255.25565,534
43138.42.0.0/16138.42.0.1 to 138.42.255.254138.42.255.25565,534
44138.43.0.0/16138.43.0.1 to 138.43.255.254138.43.255.25565,534
45138.44.0.0/16138.44.0.1 to 138.44.255.254138.44.255.25565,534
46138.45.0.0/16138.45.0.1 to 138.45.255.254138.45.255.25565,534
47138.46.0.0/16138.46.0.1 to 138.46.255.254138.46.255.25565,534
48138.47.0.0/16138.47.0.1 to 138.47.255.254138.47.255.25565,534
49138.48.0.0/16138.48.0.1 to 138.48.255.254138.48.255.25565,534
50138.49.0.0/16138.49.0.1 to 138.49.255.254138.49.255.25565,534
51138.50.0.0/16138.50.0.1 to 138.50.255.254138.50.255.25565,534
52138.51.0.0/16138.51.0.1 to 138.51.255.254138.51.255.25565,534
53138.52.0.0/16138.52.0.1 to 138.52.255.254138.52.255.25565,534
54138.53.0.0/16138.53.0.1 to 138.53.255.254138.53.255.25565,534
55138.54.0.0/16138.54.0.1 to 138.54.255.254138.54.255.25565,534
56138.55.0.0/16138.55.0.1 to 138.55.255.254138.55.255.25565,534
57138.56.0.0/16138.56.0.1 to 138.56.255.254138.56.255.25565,534
58138.57.0.0/16138.57.0.1 to 138.57.255.254138.57.255.25565,534
59138.58.0.0/16138.58.0.1 to 138.58.255.254138.58.255.25565,534
60138.59.0.0/16138.59.0.1 to 138.59.255.254138.59.255.25565,534
61138.60.0.0/16138.60.0.1 to 138.60.255.254138.60.255.25565,534
62138.61.0.0/16138.61.0.1 to 138.61.255.254138.61.255.25565,534
63138.62.0.0/16138.62.0.1 to 138.62.255.254138.62.255.25565,534
64138.63.0.0/16138.63.0.1 to 138.63.255.254138.63.255.25565,534
65138.64.0.0/16138.64.0.1 to 138.64.255.254138.64.255.25565,534
66138.65.0.0/16138.65.0.1 to 138.65.255.254138.65.255.25565,534
67138.66.0.0/16138.66.0.1 to 138.66.255.254138.66.255.25565,534
68138.67.0.0/16138.67.0.1 to 138.67.255.254138.67.255.25565,534
69138.68.0.0/16138.68.0.1 to 138.68.255.254138.68.255.25565,534
70138.69.0.0/16138.69.0.1 to 138.69.255.254138.69.255.25565,534
71138.70.0.0/16138.70.0.1 to 138.70.255.254138.70.255.25565,534
72138.71.0.0/16138.71.0.1 to 138.71.255.254138.71.255.25565,534
73138.72.0.0/16138.72.0.1 to 138.72.255.254138.72.255.25565,534
74138.73.0.0/16138.73.0.1 to 138.73.255.254138.73.255.25565,534
75138.74.0.0/16138.74.0.1 to 138.74.255.254138.74.255.25565,534
76138.75.0.0/16138.75.0.1 to 138.75.255.254138.75.255.25565,534
77138.76.0.0/16138.76.0.1 to 138.76.255.254138.76.255.25565,534
78138.77.0.0/16138.77.0.1 to 138.77.255.254138.77.255.25565,534
79138.78.0.0/16138.78.0.1 to 138.78.255.254138.78.255.25565,534
80138.79.0.0/16138.79.0.1 to 138.79.255.254138.79.255.25565,534
81138.80.0.0/16138.80.0.1 to 138.80.255.254138.80.255.25565,534
82138.81.0.0/16138.81.0.1 to 138.81.255.254138.81.255.25565,534
83138.82.0.0/16138.82.0.1 to 138.82.255.254138.82.255.25565,534
84138.83.0.0/16138.83.0.1 to 138.83.255.254138.83.255.25565,534
85138.84.0.0/16138.84.0.1 to 138.84.255.254138.84.255.25565,534
86138.85.0.0/16138.85.0.1 to 138.85.255.254138.85.255.25565,534
87138.86.0.0/16138.86.0.1 to 138.86.255.254138.86.255.25565,534
88138.87.0.0/16138.87.0.1 to 138.87.255.254138.87.255.25565,534
89138.88.0.0/16138.88.0.1 to 138.88.255.254138.88.255.25565,534
90138.89.0.0/16138.89.0.1 to 138.89.255.254138.89.255.25565,534
91138.90.0.0/16138.90.0.1 to 138.90.255.254138.90.255.25565,534
92138.91.0.0/16138.91.0.1 to 138.91.255.254138.91.255.25565,534
93138.92.0.0/16138.92.0.1 to 138.92.255.254138.92.255.25565,534
94138.93.0.0/16138.93.0.1 to 138.93.255.254138.93.255.25565,534
95138.94.0.0/16138.94.0.1 to 138.94.255.254138.94.255.25565,534
96138.95.0.0/16138.95.0.1 to 138.95.255.254138.95.255.25565,534
97138.96.0.0/16138.96.0.1 to 138.96.255.254138.96.255.25565,534
98138.97.0.0/16138.97.0.1 to 138.97.255.254138.97.255.25565,534
99138.98.0.0/16138.98.0.1 to 138.98.255.254138.98.255.25565,534
100138.99.0.0/16138.99.0.1 to 138.99.255.254138.99.255.25565,534
101138.100.0.0/16138.100.0.1 to 138.100.255.254138.100.255.25565,534
102138.101.0.0/16138.101.0.1 to 138.101.255.254138.101.255.25565,534
103138.102.0.0/16138.102.0.1 to 138.102.255.254138.102.255.25565,534
104138.103.0.0/16138.103.0.1 to 138.103.255.254138.103.255.25565,534
105138.104.0.0/16138.104.0.1 to 138.104.255.254138.104.255.25565,534
106138.105.0.0/16138.105.0.1 to 138.105.255.254138.105.255.25565,534
107138.106.0.0/16138.106.0.1 to 138.106.255.254138.106.255.25565,534
108138.107.0.0/16138.107.0.1 to 138.107.255.254138.107.255.25565,534
109138.108.0.0/16138.108.0.1 to 138.108.255.254138.108.255.25565,534
110138.109.0.0/16138.109.0.1 to 138.109.255.254138.109.255.25565,534
111138.110.0.0/16138.110.0.1 to 138.110.255.254138.110.255.25565,534
112138.111.0.0/16138.111.0.1 to 138.111.255.254138.111.255.25565,534
113138.112.0.0/16138.112.0.1 to 138.112.255.254138.112.255.25565,534
114138.113.0.0/16138.113.0.1 to 138.113.255.254138.113.255.25565,534
115138.114.0.0/16138.114.0.1 to 138.114.255.254138.114.255.25565,534
116138.115.0.0/16138.115.0.1 to 138.115.255.254138.115.255.25565,534
117138.116.0.0/16138.116.0.1 to 138.116.255.254138.116.255.25565,534
118138.117.0.0/16138.117.0.1 to 138.117.255.254138.117.255.25565,534
119138.118.0.0/16138.118.0.1 to 138.118.255.254138.118.255.25565,534
120138.119.0.0/16138.119.0.1 to 138.119.255.254138.119.255.25565,534
121138.120.0.0/16138.120.0.1 to 138.120.255.254138.120.255.25565,534
122138.121.0.0/16138.121.0.1 to 138.121.255.254138.121.255.25565,534
123138.122.0.0/16138.122.0.1 to 138.122.255.254138.122.255.25565,534
124138.123.0.0/16138.123.0.1 to 138.123.255.254138.123.255.25565,534
125138.124.0.0/16138.124.0.1 to 138.124.255.254138.124.255.25565,534
126138.125.0.0/16138.125.0.1 to 138.125.255.254138.125.255.25565,534
127138.126.0.0/16138.126.0.1 to 138.126.255.254138.126.255.25565,534
128138.127.0.0/16138.127.0.1 to 138.127.255.254138.127.255.25565,534
129138.128.0.0/16138.128.0.1 to 138.128.255.254138.128.255.25565,534
130138.129.0.0/16138.129.0.1 to 138.129.255.254138.129.255.25565,534
131138.130.0.0/16138.130.0.1 to 138.130.255.254138.130.255.25565,534
132138.131.0.0/16138.131.0.1 to 138.131.255.254138.131.255.25565,534
133138.132.0.0/16138.132.0.1 to 138.132.255.254138.132.255.25565,534
134138.133.0.0/16138.133.0.1 to 138.133.255.254138.133.255.25565,534
135138.134.0.0/16138.134.0.1 to 138.134.255.254138.134.255.25565,534
136138.135.0.0/16138.135.0.1 to 138.135.255.254138.135.255.25565,534
137138.136.0.0/16138.136.0.1 to 138.136.255.254138.136.255.25565,534
138138.137.0.0/16138.137.0.1 to 138.137.255.254138.137.255.25565,534
139138.138.0.0/16138.138.0.1 to 138.138.255.254138.138.255.25565,534
140138.139.0.0/16138.139.0.1 to 138.139.255.254138.139.255.25565,534
141138.140.0.0/16138.140.0.1 to 138.140.255.254138.140.255.25565,534
142138.141.0.0/16138.141.0.1 to 138.141.255.254138.141.255.25565,534
143138.142.0.0/16138.142.0.1 to 138.142.255.254138.142.255.25565,534
144138.143.0.0/16138.143.0.1 to 138.143.255.254138.143.255.25565,534
145138.144.0.0/16138.144.0.1 to 138.144.255.254138.144.255.25565,534
146138.145.0.0/16138.145.0.1 to 138.145.255.254138.145.255.25565,534
147138.146.0.0/16138.146.0.1 to 138.146.255.254138.146.255.25565,534
148138.147.0.0/16138.147.0.1 to 138.147.255.254138.147.255.25565,534
149138.148.0.0/16138.148.0.1 to 138.148.255.254138.148.255.25565,534
150138.149.0.0/16138.149.0.1 to 138.149.255.254138.149.255.25565,534
151138.150.0.0/16138.150.0.1 to 138.150.255.254138.150.255.25565,534
152138.151.0.0/16138.151.0.1 to 138.151.255.254138.151.255.25565,534
153138.152.0.0/16138.152.0.1 to 138.152.255.254138.152.255.25565,534
154138.153.0.0/16138.153.0.1 to 138.153.255.254138.153.255.25565,534
155138.154.0.0/16138.154.0.1 to 138.154.255.254138.154.255.25565,534
156138.155.0.0/16138.155.0.1 to 138.155.255.254138.155.255.25565,534
157138.156.0.0/16138.156.0.1 to 138.156.255.254138.156.255.25565,534
158138.157.0.0/16138.157.0.1 to 138.157.255.254138.157.255.25565,534
159138.158.0.0/16138.158.0.1 to 138.158.255.254138.158.255.25565,534
160138.159.0.0/16138.159.0.1 to 138.159.255.254138.159.255.25565,534
161138.160.0.0/16138.160.0.1 to 138.160.255.254138.160.255.25565,534
162138.161.0.0/16138.161.0.1 to 138.161.255.254138.161.255.25565,534
163138.162.0.0/16138.162.0.1 to 138.162.255.254138.162.255.25565,534
164138.163.0.0/16138.163.0.1 to 138.163.255.254138.163.255.25565,534
165138.164.0.0/16138.164.0.1 to 138.164.255.254138.164.255.25565,534
166138.165.0.0/16138.165.0.1 to 138.165.255.254138.165.255.25565,534
167138.166.0.0/16138.166.0.1 to 138.166.255.254138.166.255.25565,534
168138.167.0.0/16138.167.0.1 to 138.167.255.254138.167.255.25565,534
169138.168.0.0/16138.168.0.1 to 138.168.255.254138.168.255.25565,534
170138.169.0.0/16138.169.0.1 to 138.169.255.254138.169.255.25565,534
171138.170.0.0/16138.170.0.1 to 138.170.255.254138.170.255.25565,534
172138.171.0.0/16138.171.0.1 to 138.171.255.254138.171.255.25565,534
173138.172.0.0/16138.172.0.1 to 138.172.255.254138.172.255.25565,534
174138.173.0.0/16138.173.0.1 to 138.173.255.254138.173.255.25565,534
175138.174.0.0/16138.174.0.1 to 138.174.255.254138.174.255.25565,534
176138.175.0.0/16138.175.0.1 to 138.175.255.254138.175.255.25565,534
177138.176.0.0/16138.176.0.1 to 138.176.255.254138.176.255.25565,534
178138.177.0.0/16138.177.0.1 to 138.177.255.254138.177.255.25565,534
179138.178.0.0/16138.178.0.1 to 138.178.255.254138.178.255.25565,534
180138.179.0.0/16138.179.0.1 to 138.179.255.254138.179.255.25565,534
181138.180.0.0/16138.180.0.1 to 138.180.255.254138.180.255.25565,534
182138.181.0.0/16138.181.0.1 to 138.181.255.254138.181.255.25565,534
183138.182.0.0/16138.182.0.1 to 138.182.255.254138.182.255.25565,534
184138.183.0.0/16138.183.0.1 to 138.183.255.254138.183.255.25565,534
185138.184.0.0/16138.184.0.1 to 138.184.255.254138.184.255.25565,534
186138.185.0.0/16138.185.0.1 to 138.185.255.254138.185.255.25565,534
187138.186.0.0/16138.186.0.1 to 138.186.255.254138.186.255.25565,534
188138.187.0.0/16138.187.0.1 to 138.187.255.254138.187.255.25565,534
189138.188.0.0/16138.188.0.1 to 138.188.255.254138.188.255.25565,534
190138.189.0.0/16138.189.0.1 to 138.189.255.254138.189.255.25565,534
191138.190.0.0/16138.190.0.1 to 138.190.255.254138.190.255.25565,534
192138.191.0.0/16138.191.0.1 to 138.191.255.254138.191.255.25565,534
193138.192.0.0/16138.192.0.1 to 138.192.255.254138.192.255.25565,534
194138.193.0.0/16138.193.0.1 to 138.193.255.254138.193.255.25565,534
195138.194.0.0/16138.194.0.1 to 138.194.255.254138.194.255.25565,534
196138.195.0.0/16138.195.0.1 to 138.195.255.254138.195.255.25565,534
197138.196.0.0/16138.196.0.1 to 138.196.255.254138.196.255.25565,534
198138.197.0.0/16138.197.0.1 to 138.197.255.254138.197.255.25565,534
199138.198.0.0/16138.198.0.1 to 138.198.255.254138.198.255.25565,534
200138.199.0.0/16138.199.0.1 to 138.199.255.254138.199.255.25565,534
201138.200.0.0/16138.200.0.1 to 138.200.255.254138.200.255.25565,534
202138.201.0.0/16138.201.0.1 to 138.201.255.254138.201.255.25565,534
203138.202.0.0/16138.202.0.1 to 138.202.255.254138.202.255.25565,534
204138.203.0.0/16138.203.0.1 to 138.203.255.254138.203.255.25565,534
205138.204.0.0/16138.204.0.1 to 138.204.255.254138.204.255.25565,534
206138.205.0.0/16138.205.0.1 to 138.205.255.254138.205.255.25565,534
207138.206.0.0/16138.206.0.1 to 138.206.255.254138.206.255.25565,534
208138.207.0.0/16138.207.0.1 to 138.207.255.254138.207.255.25565,534
209138.208.0.0/16138.208.0.1 to 138.208.255.254138.208.255.25565,534
210138.209.0.0/16138.209.0.1 to 138.209.255.254138.209.255.25565,534
211138.210.0.0/16138.210.0.1 to 138.210.255.254138.210.255.25565,534
212138.211.0.0/16138.211.0.1 to 138.211.255.254138.211.255.25565,534
213138.212.0.0/16138.212.0.1 to 138.212.255.254138.212.255.25565,534
214138.213.0.0/16138.213.0.1 to 138.213.255.254138.213.255.25565,534
215138.214.0.0/16138.214.0.1 to 138.214.255.254138.214.255.25565,534
216138.215.0.0/16138.215.0.1 to 138.215.255.254138.215.255.25565,534
217138.216.0.0/16138.216.0.1 to 138.216.255.254138.216.255.25565,534
218138.217.0.0/16138.217.0.1 to 138.217.255.254138.217.255.25565,534
219138.218.0.0/16138.218.0.1 to 138.218.255.254138.218.255.25565,534
220138.219.0.0/16138.219.0.1 to 138.219.255.254138.219.255.25565,534
221138.220.0.0/16138.220.0.1 to 138.220.255.254138.220.255.25565,534
222138.221.0.0/16138.221.0.1 to 138.221.255.254138.221.255.25565,534
223138.222.0.0/16138.222.0.1 to 138.222.255.254138.222.255.25565,534
224138.223.0.0/16138.223.0.1 to 138.223.255.254138.223.255.25565,534
225138.224.0.0/16138.224.0.1 to 138.224.255.254138.224.255.25565,534
226138.225.0.0/16138.225.0.1 to 138.225.255.254138.225.255.25565,534
227138.226.0.0/16138.226.0.1 to 138.226.255.254138.226.255.25565,534
228138.227.0.0/16138.227.0.1 to 138.227.255.254138.227.255.25565,534
229138.228.0.0/16138.228.0.1 to 138.228.255.254138.228.255.25565,534
230138.229.0.0/16138.229.0.1 to 138.229.255.254138.229.255.25565,534
231138.230.0.0/16138.230.0.1 to 138.230.255.254138.230.255.25565,534
232138.231.0.0/16138.231.0.1 to 138.231.255.254138.231.255.25565,534
233138.232.0.0/16138.232.0.1 to 138.232.255.254138.232.255.25565,534
234138.233.0.0/16138.233.0.1 to 138.233.255.254138.233.255.25565,534
235138.234.0.0/16138.234.0.1 to 138.234.255.254138.234.255.25565,534
236138.235.0.0/16138.235.0.1 to 138.235.255.254138.235.255.25565,534
237138.236.0.0/16138.236.0.1 to 138.236.255.254138.236.255.25565,534
238138.237.0.0/16138.237.0.1 to 138.237.255.254138.237.255.25565,534
239138.238.0.0/16138.238.0.1 to 138.238.255.254138.238.255.25565,534
240138.239.0.0/16138.239.0.1 to 138.239.255.254138.239.255.25565,534
241138.240.0.0/16138.240.0.1 to 138.240.255.254138.240.255.25565,534
242138.241.0.0/16138.241.0.1 to 138.241.255.254138.241.255.25565,534
243138.242.0.0/16138.242.0.1 to 138.242.255.254138.242.255.25565,534
244138.243.0.0/16138.243.0.1 to 138.243.255.254138.243.255.25565,534
245138.244.0.0/16138.244.0.1 to 138.244.255.254138.244.255.25565,534
246138.245.0.0/16138.245.0.1 to 138.245.255.254138.245.255.25565,534
247138.246.0.0/16138.246.0.1 to 138.246.255.254138.246.255.25565,534
248138.247.0.0/16138.247.0.1 to 138.247.255.254138.247.255.25565,534
249138.248.0.0/16138.248.0.1 to 138.248.255.254138.248.255.25565,534
250138.249.0.0/16138.249.0.1 to 138.249.255.254138.249.255.25565,534
251138.250.0.0/16138.250.0.1 to 138.250.255.254138.250.255.25565,534
252138.251.0.0/16138.251.0.1 to 138.251.255.254138.251.255.25565,534
253138.252.0.0/16138.252.0.1 to 138.252.255.254138.252.255.25565,534
254138.253.0.0/16138.253.0.1 to 138.253.255.254138.253.255.25565,534
255138.254.0.0/16138.254.0.1 to 138.254.255.254138.254.255.25565,534
256138.255.0.0/16138.255.0.1 to 138.255.255.254138.255.255.25565,534

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.