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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.

Network138.16.0.0/12
Usable hosts1,048,574
Subnet mask255.240.0.0
Addresses1,048,576
Network address
138.16.0.0
Broadcast address
138.31.255.255
First usable
138.16.0.1
Last usable
138.31.255.254
Usable hosts
1,048,574 (1,048,576 less the network and broadcast addresses)
Subnet mask
255.240.0.0
Wildcard mask
0.15.255.255 (Cisco ACLs, OSPF)
Prefix length
/12
Type
Public public
Old class
B (default /16)
As numbers
Hex 8A100000 · Integer 2316304384 to 2317352959
Reverse DNS zones
16.138.in-addr.arpa
17.138.in-addr.arpa
18.138.in-addr.arpa
19.138.in-addr.arpa
20.138.in-addr.arpa
21.138.in-addr.arpa
22.138.in-addr.arpa
23.138.in-addr.arpa
24.138.in-addr.arpa
25.138.in-addr.arpa
26.138.in-addr.arpa
27.138.in-addr.arpa
28.138.in-addr.arpa
29.138.in-addr.arpa
30.138.in-addr.arpa
31.138.in-addr.arpa
/12 is not on a 8-bit boundary, so it takes 16 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10001010.00010000.00000000.00000000138.16.0.0
Subnet mask11111111.11110000.00000000.00000000255.240.0.0
Network10001010.00010000.00000000.00000000138.16.0.0
Broadcast10001010.00011111.11111111.11111111138.31.255.255
Split into smaller subnets/23
/13 (2)/14 (4)/15 (8)/16 (16)/17 (32)/18 (64)/19 (128)/20 (256)/21 (512)/22 (1,024)/23 (2,048)/24 (4,096)

138.16.0.0/12 makes 2,048 subnets of /23; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1138.16.0.0/23138.16.0.1 to 138.16.1.254138.16.1.255510
2138.16.2.0/23138.16.2.1 to 138.16.3.254138.16.3.255510
3138.16.4.0/23138.16.4.1 to 138.16.5.254138.16.5.255510
4138.16.6.0/23138.16.6.1 to 138.16.7.254138.16.7.255510
5138.16.8.0/23138.16.8.1 to 138.16.9.254138.16.9.255510
6138.16.10.0/23138.16.10.1 to 138.16.11.254138.16.11.255510
7138.16.12.0/23138.16.12.1 to 138.16.13.254138.16.13.255510
8138.16.14.0/23138.16.14.1 to 138.16.15.254138.16.15.255510
9138.16.16.0/23138.16.16.1 to 138.16.17.254138.16.17.255510
10138.16.18.0/23138.16.18.1 to 138.16.19.254138.16.19.255510
11138.16.20.0/23138.16.20.1 to 138.16.21.254138.16.21.255510
12138.16.22.0/23138.16.22.1 to 138.16.23.254138.16.23.255510
13138.16.24.0/23138.16.24.1 to 138.16.25.254138.16.25.255510
14138.16.26.0/23138.16.26.1 to 138.16.27.254138.16.27.255510
15138.16.28.0/23138.16.28.1 to 138.16.29.254138.16.29.255510
16138.16.30.0/23138.16.30.1 to 138.16.31.254138.16.31.255510
17138.16.32.0/23138.16.32.1 to 138.16.33.254138.16.33.255510
18138.16.34.0/23138.16.34.1 to 138.16.35.254138.16.35.255510
19138.16.36.0/23138.16.36.1 to 138.16.37.254138.16.37.255510
20138.16.38.0/23138.16.38.1 to 138.16.39.254138.16.39.255510
21138.16.40.0/23138.16.40.1 to 138.16.41.254138.16.41.255510
22138.16.42.0/23138.16.42.1 to 138.16.43.254138.16.43.255510
23138.16.44.0/23138.16.44.1 to 138.16.45.254138.16.45.255510
24138.16.46.0/23138.16.46.1 to 138.16.47.254138.16.47.255510
25138.16.48.0/23138.16.48.1 to 138.16.49.254138.16.49.255510
26138.16.50.0/23138.16.50.1 to 138.16.51.254138.16.51.255510
27138.16.52.0/23138.16.52.1 to 138.16.53.254138.16.53.255510
28138.16.54.0/23138.16.54.1 to 138.16.55.254138.16.55.255510
29138.16.56.0/23138.16.56.1 to 138.16.57.254138.16.57.255510
30138.16.58.0/23138.16.58.1 to 138.16.59.254138.16.59.255510
31138.16.60.0/23138.16.60.1 to 138.16.61.254138.16.61.255510
32138.16.62.0/23138.16.62.1 to 138.16.63.254138.16.63.255510
33138.16.64.0/23138.16.64.1 to 138.16.65.254138.16.65.255510
34138.16.66.0/23138.16.66.1 to 138.16.67.254138.16.67.255510
35138.16.68.0/23138.16.68.1 to 138.16.69.254138.16.69.255510
36138.16.70.0/23138.16.70.1 to 138.16.71.254138.16.71.255510
37138.16.72.0/23138.16.72.1 to 138.16.73.254138.16.73.255510
38138.16.74.0/23138.16.74.1 to 138.16.75.254138.16.75.255510
39138.16.76.0/23138.16.76.1 to 138.16.77.254138.16.77.255510
40138.16.78.0/23138.16.78.1 to 138.16.79.254138.16.79.255510
41138.16.80.0/23138.16.80.1 to 138.16.81.254138.16.81.255510
42138.16.82.0/23138.16.82.1 to 138.16.83.254138.16.83.255510
43138.16.84.0/23138.16.84.1 to 138.16.85.254138.16.85.255510
44138.16.86.0/23138.16.86.1 to 138.16.87.254138.16.87.255510
45138.16.88.0/23138.16.88.1 to 138.16.89.254138.16.89.255510
46138.16.90.0/23138.16.90.1 to 138.16.91.254138.16.91.255510
47138.16.92.0/23138.16.92.1 to 138.16.93.254138.16.93.255510
48138.16.94.0/23138.16.94.1 to 138.16.95.254138.16.95.255510
49138.16.96.0/23138.16.96.1 to 138.16.97.254138.16.97.255510
50138.16.98.0/23138.16.98.1 to 138.16.99.254138.16.99.255510
51138.16.100.0/23138.16.100.1 to 138.16.101.254138.16.101.255510
52138.16.102.0/23138.16.102.1 to 138.16.103.254138.16.103.255510
53138.16.104.0/23138.16.104.1 to 138.16.105.254138.16.105.255510
54138.16.106.0/23138.16.106.1 to 138.16.107.254138.16.107.255510
55138.16.108.0/23138.16.108.1 to 138.16.109.254138.16.109.255510
56138.16.110.0/23138.16.110.1 to 138.16.111.254138.16.111.255510
57138.16.112.0/23138.16.112.1 to 138.16.113.254138.16.113.255510
58138.16.114.0/23138.16.114.1 to 138.16.115.254138.16.115.255510
59138.16.116.0/23138.16.116.1 to 138.16.117.254138.16.117.255510
60138.16.118.0/23138.16.118.1 to 138.16.119.254138.16.119.255510
61138.16.120.0/23138.16.120.1 to 138.16.121.254138.16.121.255510
62138.16.122.0/23138.16.122.1 to 138.16.123.254138.16.123.255510
63138.16.124.0/23138.16.124.1 to 138.16.125.254138.16.125.255510
64138.16.126.0/23138.16.126.1 to 138.16.127.254138.16.127.255510
65138.16.128.0/23138.16.128.1 to 138.16.129.254138.16.129.255510
66138.16.130.0/23138.16.130.1 to 138.16.131.254138.16.131.255510
67138.16.132.0/23138.16.132.1 to 138.16.133.254138.16.133.255510
68138.16.134.0/23138.16.134.1 to 138.16.135.254138.16.135.255510
69138.16.136.0/23138.16.136.1 to 138.16.137.254138.16.137.255510
70138.16.138.0/23138.16.138.1 to 138.16.139.254138.16.139.255510
71138.16.140.0/23138.16.140.1 to 138.16.141.254138.16.141.255510
72138.16.142.0/23138.16.142.1 to 138.16.143.254138.16.143.255510
73138.16.144.0/23138.16.144.1 to 138.16.145.254138.16.145.255510
74138.16.146.0/23138.16.146.1 to 138.16.147.254138.16.147.255510
75138.16.148.0/23138.16.148.1 to 138.16.149.254138.16.149.255510
76138.16.150.0/23138.16.150.1 to 138.16.151.254138.16.151.255510
77138.16.152.0/23138.16.152.1 to 138.16.153.254138.16.153.255510
78138.16.154.0/23138.16.154.1 to 138.16.155.254138.16.155.255510
79138.16.156.0/23138.16.156.1 to 138.16.157.254138.16.157.255510
80138.16.158.0/23138.16.158.1 to 138.16.159.254138.16.159.255510
81138.16.160.0/23138.16.160.1 to 138.16.161.254138.16.161.255510
82138.16.162.0/23138.16.162.1 to 138.16.163.254138.16.163.255510
83138.16.164.0/23138.16.164.1 to 138.16.165.254138.16.165.255510
84138.16.166.0/23138.16.166.1 to 138.16.167.254138.16.167.255510
85138.16.168.0/23138.16.168.1 to 138.16.169.254138.16.169.255510
86138.16.170.0/23138.16.170.1 to 138.16.171.254138.16.171.255510
87138.16.172.0/23138.16.172.1 to 138.16.173.254138.16.173.255510
88138.16.174.0/23138.16.174.1 to 138.16.175.254138.16.175.255510
89138.16.176.0/23138.16.176.1 to 138.16.177.254138.16.177.255510
90138.16.178.0/23138.16.178.1 to 138.16.179.254138.16.179.255510
91138.16.180.0/23138.16.180.1 to 138.16.181.254138.16.181.255510
92138.16.182.0/23138.16.182.1 to 138.16.183.254138.16.183.255510
93138.16.184.0/23138.16.184.1 to 138.16.185.254138.16.185.255510
94138.16.186.0/23138.16.186.1 to 138.16.187.254138.16.187.255510
95138.16.188.0/23138.16.188.1 to 138.16.189.254138.16.189.255510
96138.16.190.0/23138.16.190.1 to 138.16.191.254138.16.191.255510
97138.16.192.0/23138.16.192.1 to 138.16.193.254138.16.193.255510
98138.16.194.0/23138.16.194.1 to 138.16.195.254138.16.195.255510
99138.16.196.0/23138.16.196.1 to 138.16.197.254138.16.197.255510
100138.16.198.0/23138.16.198.1 to 138.16.199.254138.16.199.255510
101138.16.200.0/23138.16.200.1 to 138.16.201.254138.16.201.255510
102138.16.202.0/23138.16.202.1 to 138.16.203.254138.16.203.255510
103138.16.204.0/23138.16.204.1 to 138.16.205.254138.16.205.255510
104138.16.206.0/23138.16.206.1 to 138.16.207.254138.16.207.255510
105138.16.208.0/23138.16.208.1 to 138.16.209.254138.16.209.255510
106138.16.210.0/23138.16.210.1 to 138.16.211.254138.16.211.255510
107138.16.212.0/23138.16.212.1 to 138.16.213.254138.16.213.255510
108138.16.214.0/23138.16.214.1 to 138.16.215.254138.16.215.255510
109138.16.216.0/23138.16.216.1 to 138.16.217.254138.16.217.255510
110138.16.218.0/23138.16.218.1 to 138.16.219.254138.16.219.255510
111138.16.220.0/23138.16.220.1 to 138.16.221.254138.16.221.255510
112138.16.222.0/23138.16.222.1 to 138.16.223.254138.16.223.255510
113138.16.224.0/23138.16.224.1 to 138.16.225.254138.16.225.255510
114138.16.226.0/23138.16.226.1 to 138.16.227.254138.16.227.255510
115138.16.228.0/23138.16.228.1 to 138.16.229.254138.16.229.255510
116138.16.230.0/23138.16.230.1 to 138.16.231.254138.16.231.255510
117138.16.232.0/23138.16.232.1 to 138.16.233.254138.16.233.255510
118138.16.234.0/23138.16.234.1 to 138.16.235.254138.16.235.255510
119138.16.236.0/23138.16.236.1 to 138.16.237.254138.16.237.255510
120138.16.238.0/23138.16.238.1 to 138.16.239.254138.16.239.255510
121138.16.240.0/23138.16.240.1 to 138.16.241.254138.16.241.255510
122138.16.242.0/23138.16.242.1 to 138.16.243.254138.16.243.255510
123138.16.244.0/23138.16.244.1 to 138.16.245.254138.16.245.255510
124138.16.246.0/23138.16.246.1 to 138.16.247.254138.16.247.255510
125138.16.248.0/23138.16.248.1 to 138.16.249.254138.16.249.255510
126138.16.250.0/23138.16.250.1 to 138.16.251.254138.16.251.255510
127138.16.252.0/23138.16.252.1 to 138.16.253.254138.16.253.255510
128138.16.254.0/23138.16.254.1 to 138.16.255.254138.16.255.255510
129138.17.0.0/23138.17.0.1 to 138.17.1.254138.17.1.255510
130138.17.2.0/23138.17.2.1 to 138.17.3.254138.17.3.255510
131138.17.4.0/23138.17.4.1 to 138.17.5.254138.17.5.255510
132138.17.6.0/23138.17.6.1 to 138.17.7.254138.17.7.255510
133138.17.8.0/23138.17.8.1 to 138.17.9.254138.17.9.255510
134138.17.10.0/23138.17.10.1 to 138.17.11.254138.17.11.255510
135138.17.12.0/23138.17.12.1 to 138.17.13.254138.17.13.255510
136138.17.14.0/23138.17.14.1 to 138.17.15.254138.17.15.255510
137138.17.16.0/23138.17.16.1 to 138.17.17.254138.17.17.255510
138138.17.18.0/23138.17.18.1 to 138.17.19.254138.17.19.255510
139138.17.20.0/23138.17.20.1 to 138.17.21.254138.17.21.255510
140138.17.22.0/23138.17.22.1 to 138.17.23.254138.17.23.255510
141138.17.24.0/23138.17.24.1 to 138.17.25.254138.17.25.255510
142138.17.26.0/23138.17.26.1 to 138.17.27.254138.17.27.255510
143138.17.28.0/23138.17.28.1 to 138.17.29.254138.17.29.255510
144138.17.30.0/23138.17.30.1 to 138.17.31.254138.17.31.255510
145138.17.32.0/23138.17.32.1 to 138.17.33.254138.17.33.255510
146138.17.34.0/23138.17.34.1 to 138.17.35.254138.17.35.255510
147138.17.36.0/23138.17.36.1 to 138.17.37.254138.17.37.255510
148138.17.38.0/23138.17.38.1 to 138.17.39.254138.17.39.255510
149138.17.40.0/23138.17.40.1 to 138.17.41.254138.17.41.255510
150138.17.42.0/23138.17.42.1 to 138.17.43.254138.17.43.255510
151138.17.44.0/23138.17.44.1 to 138.17.45.254138.17.45.255510
152138.17.46.0/23138.17.46.1 to 138.17.47.254138.17.47.255510
153138.17.48.0/23138.17.48.1 to 138.17.49.254138.17.49.255510
154138.17.50.0/23138.17.50.1 to 138.17.51.254138.17.51.255510
155138.17.52.0/23138.17.52.1 to 138.17.53.254138.17.53.255510
156138.17.54.0/23138.17.54.1 to 138.17.55.254138.17.55.255510
157138.17.56.0/23138.17.56.1 to 138.17.57.254138.17.57.255510
158138.17.58.0/23138.17.58.1 to 138.17.59.254138.17.59.255510
159138.17.60.0/23138.17.60.1 to 138.17.61.254138.17.61.255510
160138.17.62.0/23138.17.62.1 to 138.17.63.254138.17.63.255510
161138.17.64.0/23138.17.64.1 to 138.17.65.254138.17.65.255510
162138.17.66.0/23138.17.66.1 to 138.17.67.254138.17.67.255510
163138.17.68.0/23138.17.68.1 to 138.17.69.254138.17.69.255510
164138.17.70.0/23138.17.70.1 to 138.17.71.254138.17.71.255510
165138.17.72.0/23138.17.72.1 to 138.17.73.254138.17.73.255510
166138.17.74.0/23138.17.74.1 to 138.17.75.254138.17.75.255510
167138.17.76.0/23138.17.76.1 to 138.17.77.254138.17.77.255510
168138.17.78.0/23138.17.78.1 to 138.17.79.254138.17.79.255510
169138.17.80.0/23138.17.80.1 to 138.17.81.254138.17.81.255510
170138.17.82.0/23138.17.82.1 to 138.17.83.254138.17.83.255510
171138.17.84.0/23138.17.84.1 to 138.17.85.254138.17.85.255510
172138.17.86.0/23138.17.86.1 to 138.17.87.254138.17.87.255510
173138.17.88.0/23138.17.88.1 to 138.17.89.254138.17.89.255510
174138.17.90.0/23138.17.90.1 to 138.17.91.254138.17.91.255510
175138.17.92.0/23138.17.92.1 to 138.17.93.254138.17.93.255510
176138.17.94.0/23138.17.94.1 to 138.17.95.254138.17.95.255510
177138.17.96.0/23138.17.96.1 to 138.17.97.254138.17.97.255510
178138.17.98.0/23138.17.98.1 to 138.17.99.254138.17.99.255510
179138.17.100.0/23138.17.100.1 to 138.17.101.254138.17.101.255510
180138.17.102.0/23138.17.102.1 to 138.17.103.254138.17.103.255510
181138.17.104.0/23138.17.104.1 to 138.17.105.254138.17.105.255510
182138.17.106.0/23138.17.106.1 to 138.17.107.254138.17.107.255510
183138.17.108.0/23138.17.108.1 to 138.17.109.254138.17.109.255510
184138.17.110.0/23138.17.110.1 to 138.17.111.254138.17.111.255510
185138.17.112.0/23138.17.112.1 to 138.17.113.254138.17.113.255510
186138.17.114.0/23138.17.114.1 to 138.17.115.254138.17.115.255510
187138.17.116.0/23138.17.116.1 to 138.17.117.254138.17.117.255510
188138.17.118.0/23138.17.118.1 to 138.17.119.254138.17.119.255510
189138.17.120.0/23138.17.120.1 to 138.17.121.254138.17.121.255510
190138.17.122.0/23138.17.122.1 to 138.17.123.254138.17.123.255510
191138.17.124.0/23138.17.124.1 to 138.17.125.254138.17.125.255510
192138.17.126.0/23138.17.126.1 to 138.17.127.254138.17.127.255510
193138.17.128.0/23138.17.128.1 to 138.17.129.254138.17.129.255510
194138.17.130.0/23138.17.130.1 to 138.17.131.254138.17.131.255510
195138.17.132.0/23138.17.132.1 to 138.17.133.254138.17.133.255510
196138.17.134.0/23138.17.134.1 to 138.17.135.254138.17.135.255510
197138.17.136.0/23138.17.136.1 to 138.17.137.254138.17.137.255510
198138.17.138.0/23138.17.138.1 to 138.17.139.254138.17.139.255510
199138.17.140.0/23138.17.140.1 to 138.17.141.254138.17.141.255510
200138.17.142.0/23138.17.142.1 to 138.17.143.254138.17.143.255510
201138.17.144.0/23138.17.144.1 to 138.17.145.254138.17.145.255510
202138.17.146.0/23138.17.146.1 to 138.17.147.254138.17.147.255510
203138.17.148.0/23138.17.148.1 to 138.17.149.254138.17.149.255510
204138.17.150.0/23138.17.150.1 to 138.17.151.254138.17.151.255510
205138.17.152.0/23138.17.152.1 to 138.17.153.254138.17.153.255510
206138.17.154.0/23138.17.154.1 to 138.17.155.254138.17.155.255510
207138.17.156.0/23138.17.156.1 to 138.17.157.254138.17.157.255510
208138.17.158.0/23138.17.158.1 to 138.17.159.254138.17.159.255510
209138.17.160.0/23138.17.160.1 to 138.17.161.254138.17.161.255510
210138.17.162.0/23138.17.162.1 to 138.17.163.254138.17.163.255510
211138.17.164.0/23138.17.164.1 to 138.17.165.254138.17.165.255510
212138.17.166.0/23138.17.166.1 to 138.17.167.254138.17.167.255510
213138.17.168.0/23138.17.168.1 to 138.17.169.254138.17.169.255510
214138.17.170.0/23138.17.170.1 to 138.17.171.254138.17.171.255510
215138.17.172.0/23138.17.172.1 to 138.17.173.254138.17.173.255510
216138.17.174.0/23138.17.174.1 to 138.17.175.254138.17.175.255510
217138.17.176.0/23138.17.176.1 to 138.17.177.254138.17.177.255510
218138.17.178.0/23138.17.178.1 to 138.17.179.254138.17.179.255510
219138.17.180.0/23138.17.180.1 to 138.17.181.254138.17.181.255510
220138.17.182.0/23138.17.182.1 to 138.17.183.254138.17.183.255510
221138.17.184.0/23138.17.184.1 to 138.17.185.254138.17.185.255510
222138.17.186.0/23138.17.186.1 to 138.17.187.254138.17.187.255510
223138.17.188.0/23138.17.188.1 to 138.17.189.254138.17.189.255510
224138.17.190.0/23138.17.190.1 to 138.17.191.254138.17.191.255510
225138.17.192.0/23138.17.192.1 to 138.17.193.254138.17.193.255510
226138.17.194.0/23138.17.194.1 to 138.17.195.254138.17.195.255510
227138.17.196.0/23138.17.196.1 to 138.17.197.254138.17.197.255510
228138.17.198.0/23138.17.198.1 to 138.17.199.254138.17.199.255510
229138.17.200.0/23138.17.200.1 to 138.17.201.254138.17.201.255510
230138.17.202.0/23138.17.202.1 to 138.17.203.254138.17.203.255510
231138.17.204.0/23138.17.204.1 to 138.17.205.254138.17.205.255510
232138.17.206.0/23138.17.206.1 to 138.17.207.254138.17.207.255510
233138.17.208.0/23138.17.208.1 to 138.17.209.254138.17.209.255510
234138.17.210.0/23138.17.210.1 to 138.17.211.254138.17.211.255510
235138.17.212.0/23138.17.212.1 to 138.17.213.254138.17.213.255510
236138.17.214.0/23138.17.214.1 to 138.17.215.254138.17.215.255510
237138.17.216.0/23138.17.216.1 to 138.17.217.254138.17.217.255510
238138.17.218.0/23138.17.218.1 to 138.17.219.254138.17.219.255510
239138.17.220.0/23138.17.220.1 to 138.17.221.254138.17.221.255510
240138.17.222.0/23138.17.222.1 to 138.17.223.254138.17.223.255510
241138.17.224.0/23138.17.224.1 to 138.17.225.254138.17.225.255510
242138.17.226.0/23138.17.226.1 to 138.17.227.254138.17.227.255510
243138.17.228.0/23138.17.228.1 to 138.17.229.254138.17.229.255510
244138.17.230.0/23138.17.230.1 to 138.17.231.254138.17.231.255510
245138.17.232.0/23138.17.232.1 to 138.17.233.254138.17.233.255510
246138.17.234.0/23138.17.234.1 to 138.17.235.254138.17.235.255510
247138.17.236.0/23138.17.236.1 to 138.17.237.254138.17.237.255510
248138.17.238.0/23138.17.238.1 to 138.17.239.254138.17.239.255510
249138.17.240.0/23138.17.240.1 to 138.17.241.254138.17.241.255510
250138.17.242.0/23138.17.242.1 to 138.17.243.254138.17.243.255510
251138.17.244.0/23138.17.244.1 to 138.17.245.254138.17.245.255510
252138.17.246.0/23138.17.246.1 to 138.17.247.254138.17.247.255510
253138.17.248.0/23138.17.248.1 to 138.17.249.254138.17.249.255510
254138.17.250.0/23138.17.250.1 to 138.17.251.254138.17.251.255510
255138.17.252.0/23138.17.252.1 to 138.17.253.254138.17.253.255510
256138.17.254.0/23138.17.254.1 to 138.17.255.254138.17.255.255510

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.