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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.

Network183.0.0.0/12
Usable hosts1,048,574
Subnet mask255.240.0.0
Addresses1,048,576
Network address
183.0.0.0
Broadcast address
183.15.255.255
First usable
183.0.0.1
Last usable
183.15.255.254
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 B7000000 · Integer 3070230528 to 3071279103
Reverse DNS zones
0.183.in-addr.arpa
1.183.in-addr.arpa
2.183.in-addr.arpa
3.183.in-addr.arpa
4.183.in-addr.arpa
5.183.in-addr.arpa
6.183.in-addr.arpa
7.183.in-addr.arpa
8.183.in-addr.arpa
9.183.in-addr.arpa
10.183.in-addr.arpa
11.183.in-addr.arpa
12.183.in-addr.arpa
13.183.in-addr.arpa
14.183.in-addr.arpa
15.183.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
Address10110111.00000000.00000000.00000000183.0.0.0
Subnet mask11111111.11110000.00000000.00000000255.240.0.0
Network10110111.00000000.00000000.00000000183.0.0.0
Broadcast10110111.00001111.11111111.11111111183.15.255.255
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)

183.0.0.0/12 makes 2,048 subnets of /23; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1183.0.0.0/23183.0.0.1 to 183.0.1.254183.0.1.255510
2183.0.2.0/23183.0.2.1 to 183.0.3.254183.0.3.255510
3183.0.4.0/23183.0.4.1 to 183.0.5.254183.0.5.255510
4183.0.6.0/23183.0.6.1 to 183.0.7.254183.0.7.255510
5183.0.8.0/23183.0.8.1 to 183.0.9.254183.0.9.255510
6183.0.10.0/23183.0.10.1 to 183.0.11.254183.0.11.255510
7183.0.12.0/23183.0.12.1 to 183.0.13.254183.0.13.255510
8183.0.14.0/23183.0.14.1 to 183.0.15.254183.0.15.255510
9183.0.16.0/23183.0.16.1 to 183.0.17.254183.0.17.255510
10183.0.18.0/23183.0.18.1 to 183.0.19.254183.0.19.255510
11183.0.20.0/23183.0.20.1 to 183.0.21.254183.0.21.255510
12183.0.22.0/23183.0.22.1 to 183.0.23.254183.0.23.255510
13183.0.24.0/23183.0.24.1 to 183.0.25.254183.0.25.255510
14183.0.26.0/23183.0.26.1 to 183.0.27.254183.0.27.255510
15183.0.28.0/23183.0.28.1 to 183.0.29.254183.0.29.255510
16183.0.30.0/23183.0.30.1 to 183.0.31.254183.0.31.255510
17183.0.32.0/23183.0.32.1 to 183.0.33.254183.0.33.255510
18183.0.34.0/23183.0.34.1 to 183.0.35.254183.0.35.255510
19183.0.36.0/23183.0.36.1 to 183.0.37.254183.0.37.255510
20183.0.38.0/23183.0.38.1 to 183.0.39.254183.0.39.255510
21183.0.40.0/23183.0.40.1 to 183.0.41.254183.0.41.255510
22183.0.42.0/23183.0.42.1 to 183.0.43.254183.0.43.255510
23183.0.44.0/23183.0.44.1 to 183.0.45.254183.0.45.255510
24183.0.46.0/23183.0.46.1 to 183.0.47.254183.0.47.255510
25183.0.48.0/23183.0.48.1 to 183.0.49.254183.0.49.255510
26183.0.50.0/23183.0.50.1 to 183.0.51.254183.0.51.255510
27183.0.52.0/23183.0.52.1 to 183.0.53.254183.0.53.255510
28183.0.54.0/23183.0.54.1 to 183.0.55.254183.0.55.255510
29183.0.56.0/23183.0.56.1 to 183.0.57.254183.0.57.255510
30183.0.58.0/23183.0.58.1 to 183.0.59.254183.0.59.255510
31183.0.60.0/23183.0.60.1 to 183.0.61.254183.0.61.255510
32183.0.62.0/23183.0.62.1 to 183.0.63.254183.0.63.255510
33183.0.64.0/23183.0.64.1 to 183.0.65.254183.0.65.255510
34183.0.66.0/23183.0.66.1 to 183.0.67.254183.0.67.255510
35183.0.68.0/23183.0.68.1 to 183.0.69.254183.0.69.255510
36183.0.70.0/23183.0.70.1 to 183.0.71.254183.0.71.255510
37183.0.72.0/23183.0.72.1 to 183.0.73.254183.0.73.255510
38183.0.74.0/23183.0.74.1 to 183.0.75.254183.0.75.255510
39183.0.76.0/23183.0.76.1 to 183.0.77.254183.0.77.255510
40183.0.78.0/23183.0.78.1 to 183.0.79.254183.0.79.255510
41183.0.80.0/23183.0.80.1 to 183.0.81.254183.0.81.255510
42183.0.82.0/23183.0.82.1 to 183.0.83.254183.0.83.255510
43183.0.84.0/23183.0.84.1 to 183.0.85.254183.0.85.255510
44183.0.86.0/23183.0.86.1 to 183.0.87.254183.0.87.255510
45183.0.88.0/23183.0.88.1 to 183.0.89.254183.0.89.255510
46183.0.90.0/23183.0.90.1 to 183.0.91.254183.0.91.255510
47183.0.92.0/23183.0.92.1 to 183.0.93.254183.0.93.255510
48183.0.94.0/23183.0.94.1 to 183.0.95.254183.0.95.255510
49183.0.96.0/23183.0.96.1 to 183.0.97.254183.0.97.255510
50183.0.98.0/23183.0.98.1 to 183.0.99.254183.0.99.255510
51183.0.100.0/23183.0.100.1 to 183.0.101.254183.0.101.255510
52183.0.102.0/23183.0.102.1 to 183.0.103.254183.0.103.255510
53183.0.104.0/23183.0.104.1 to 183.0.105.254183.0.105.255510
54183.0.106.0/23183.0.106.1 to 183.0.107.254183.0.107.255510
55183.0.108.0/23183.0.108.1 to 183.0.109.254183.0.109.255510
56183.0.110.0/23183.0.110.1 to 183.0.111.254183.0.111.255510
57183.0.112.0/23183.0.112.1 to 183.0.113.254183.0.113.255510
58183.0.114.0/23183.0.114.1 to 183.0.115.254183.0.115.255510
59183.0.116.0/23183.0.116.1 to 183.0.117.254183.0.117.255510
60183.0.118.0/23183.0.118.1 to 183.0.119.254183.0.119.255510
61183.0.120.0/23183.0.120.1 to 183.0.121.254183.0.121.255510
62183.0.122.0/23183.0.122.1 to 183.0.123.254183.0.123.255510
63183.0.124.0/23183.0.124.1 to 183.0.125.254183.0.125.255510
64183.0.126.0/23183.0.126.1 to 183.0.127.254183.0.127.255510
65183.0.128.0/23183.0.128.1 to 183.0.129.254183.0.129.255510
66183.0.130.0/23183.0.130.1 to 183.0.131.254183.0.131.255510
67183.0.132.0/23183.0.132.1 to 183.0.133.254183.0.133.255510
68183.0.134.0/23183.0.134.1 to 183.0.135.254183.0.135.255510
69183.0.136.0/23183.0.136.1 to 183.0.137.254183.0.137.255510
70183.0.138.0/23183.0.138.1 to 183.0.139.254183.0.139.255510
71183.0.140.0/23183.0.140.1 to 183.0.141.254183.0.141.255510
72183.0.142.0/23183.0.142.1 to 183.0.143.254183.0.143.255510
73183.0.144.0/23183.0.144.1 to 183.0.145.254183.0.145.255510
74183.0.146.0/23183.0.146.1 to 183.0.147.254183.0.147.255510
75183.0.148.0/23183.0.148.1 to 183.0.149.254183.0.149.255510
76183.0.150.0/23183.0.150.1 to 183.0.151.254183.0.151.255510
77183.0.152.0/23183.0.152.1 to 183.0.153.254183.0.153.255510
78183.0.154.0/23183.0.154.1 to 183.0.155.254183.0.155.255510
79183.0.156.0/23183.0.156.1 to 183.0.157.254183.0.157.255510
80183.0.158.0/23183.0.158.1 to 183.0.159.254183.0.159.255510
81183.0.160.0/23183.0.160.1 to 183.0.161.254183.0.161.255510
82183.0.162.0/23183.0.162.1 to 183.0.163.254183.0.163.255510
83183.0.164.0/23183.0.164.1 to 183.0.165.254183.0.165.255510
84183.0.166.0/23183.0.166.1 to 183.0.167.254183.0.167.255510
85183.0.168.0/23183.0.168.1 to 183.0.169.254183.0.169.255510
86183.0.170.0/23183.0.170.1 to 183.0.171.254183.0.171.255510
87183.0.172.0/23183.0.172.1 to 183.0.173.254183.0.173.255510
88183.0.174.0/23183.0.174.1 to 183.0.175.254183.0.175.255510
89183.0.176.0/23183.0.176.1 to 183.0.177.254183.0.177.255510
90183.0.178.0/23183.0.178.1 to 183.0.179.254183.0.179.255510
91183.0.180.0/23183.0.180.1 to 183.0.181.254183.0.181.255510
92183.0.182.0/23183.0.182.1 to 183.0.183.254183.0.183.255510
93183.0.184.0/23183.0.184.1 to 183.0.185.254183.0.185.255510
94183.0.186.0/23183.0.186.1 to 183.0.187.254183.0.187.255510
95183.0.188.0/23183.0.188.1 to 183.0.189.254183.0.189.255510
96183.0.190.0/23183.0.190.1 to 183.0.191.254183.0.191.255510
97183.0.192.0/23183.0.192.1 to 183.0.193.254183.0.193.255510
98183.0.194.0/23183.0.194.1 to 183.0.195.254183.0.195.255510
99183.0.196.0/23183.0.196.1 to 183.0.197.254183.0.197.255510
100183.0.198.0/23183.0.198.1 to 183.0.199.254183.0.199.255510
101183.0.200.0/23183.0.200.1 to 183.0.201.254183.0.201.255510
102183.0.202.0/23183.0.202.1 to 183.0.203.254183.0.203.255510
103183.0.204.0/23183.0.204.1 to 183.0.205.254183.0.205.255510
104183.0.206.0/23183.0.206.1 to 183.0.207.254183.0.207.255510
105183.0.208.0/23183.0.208.1 to 183.0.209.254183.0.209.255510
106183.0.210.0/23183.0.210.1 to 183.0.211.254183.0.211.255510
107183.0.212.0/23183.0.212.1 to 183.0.213.254183.0.213.255510
108183.0.214.0/23183.0.214.1 to 183.0.215.254183.0.215.255510
109183.0.216.0/23183.0.216.1 to 183.0.217.254183.0.217.255510
110183.0.218.0/23183.0.218.1 to 183.0.219.254183.0.219.255510
111183.0.220.0/23183.0.220.1 to 183.0.221.254183.0.221.255510
112183.0.222.0/23183.0.222.1 to 183.0.223.254183.0.223.255510
113183.0.224.0/23183.0.224.1 to 183.0.225.254183.0.225.255510
114183.0.226.0/23183.0.226.1 to 183.0.227.254183.0.227.255510
115183.0.228.0/23183.0.228.1 to 183.0.229.254183.0.229.255510
116183.0.230.0/23183.0.230.1 to 183.0.231.254183.0.231.255510
117183.0.232.0/23183.0.232.1 to 183.0.233.254183.0.233.255510
118183.0.234.0/23183.0.234.1 to 183.0.235.254183.0.235.255510
119183.0.236.0/23183.0.236.1 to 183.0.237.254183.0.237.255510
120183.0.238.0/23183.0.238.1 to 183.0.239.254183.0.239.255510
121183.0.240.0/23183.0.240.1 to 183.0.241.254183.0.241.255510
122183.0.242.0/23183.0.242.1 to 183.0.243.254183.0.243.255510
123183.0.244.0/23183.0.244.1 to 183.0.245.254183.0.245.255510
124183.0.246.0/23183.0.246.1 to 183.0.247.254183.0.247.255510
125183.0.248.0/23183.0.248.1 to 183.0.249.254183.0.249.255510
126183.0.250.0/23183.0.250.1 to 183.0.251.254183.0.251.255510
127183.0.252.0/23183.0.252.1 to 183.0.253.254183.0.253.255510
128183.0.254.0/23183.0.254.1 to 183.0.255.254183.0.255.255510
129183.1.0.0/23183.1.0.1 to 183.1.1.254183.1.1.255510
130183.1.2.0/23183.1.2.1 to 183.1.3.254183.1.3.255510
131183.1.4.0/23183.1.4.1 to 183.1.5.254183.1.5.255510
132183.1.6.0/23183.1.6.1 to 183.1.7.254183.1.7.255510
133183.1.8.0/23183.1.8.1 to 183.1.9.254183.1.9.255510
134183.1.10.0/23183.1.10.1 to 183.1.11.254183.1.11.255510
135183.1.12.0/23183.1.12.1 to 183.1.13.254183.1.13.255510
136183.1.14.0/23183.1.14.1 to 183.1.15.254183.1.15.255510
137183.1.16.0/23183.1.16.1 to 183.1.17.254183.1.17.255510
138183.1.18.0/23183.1.18.1 to 183.1.19.254183.1.19.255510
139183.1.20.0/23183.1.20.1 to 183.1.21.254183.1.21.255510
140183.1.22.0/23183.1.22.1 to 183.1.23.254183.1.23.255510
141183.1.24.0/23183.1.24.1 to 183.1.25.254183.1.25.255510
142183.1.26.0/23183.1.26.1 to 183.1.27.254183.1.27.255510
143183.1.28.0/23183.1.28.1 to 183.1.29.254183.1.29.255510
144183.1.30.0/23183.1.30.1 to 183.1.31.254183.1.31.255510
145183.1.32.0/23183.1.32.1 to 183.1.33.254183.1.33.255510
146183.1.34.0/23183.1.34.1 to 183.1.35.254183.1.35.255510
147183.1.36.0/23183.1.36.1 to 183.1.37.254183.1.37.255510
148183.1.38.0/23183.1.38.1 to 183.1.39.254183.1.39.255510
149183.1.40.0/23183.1.40.1 to 183.1.41.254183.1.41.255510
150183.1.42.0/23183.1.42.1 to 183.1.43.254183.1.43.255510
151183.1.44.0/23183.1.44.1 to 183.1.45.254183.1.45.255510
152183.1.46.0/23183.1.46.1 to 183.1.47.254183.1.47.255510
153183.1.48.0/23183.1.48.1 to 183.1.49.254183.1.49.255510
154183.1.50.0/23183.1.50.1 to 183.1.51.254183.1.51.255510
155183.1.52.0/23183.1.52.1 to 183.1.53.254183.1.53.255510
156183.1.54.0/23183.1.54.1 to 183.1.55.254183.1.55.255510
157183.1.56.0/23183.1.56.1 to 183.1.57.254183.1.57.255510
158183.1.58.0/23183.1.58.1 to 183.1.59.254183.1.59.255510
159183.1.60.0/23183.1.60.1 to 183.1.61.254183.1.61.255510
160183.1.62.0/23183.1.62.1 to 183.1.63.254183.1.63.255510
161183.1.64.0/23183.1.64.1 to 183.1.65.254183.1.65.255510
162183.1.66.0/23183.1.66.1 to 183.1.67.254183.1.67.255510
163183.1.68.0/23183.1.68.1 to 183.1.69.254183.1.69.255510
164183.1.70.0/23183.1.70.1 to 183.1.71.254183.1.71.255510
165183.1.72.0/23183.1.72.1 to 183.1.73.254183.1.73.255510
166183.1.74.0/23183.1.74.1 to 183.1.75.254183.1.75.255510
167183.1.76.0/23183.1.76.1 to 183.1.77.254183.1.77.255510
168183.1.78.0/23183.1.78.1 to 183.1.79.254183.1.79.255510
169183.1.80.0/23183.1.80.1 to 183.1.81.254183.1.81.255510
170183.1.82.0/23183.1.82.1 to 183.1.83.254183.1.83.255510
171183.1.84.0/23183.1.84.1 to 183.1.85.254183.1.85.255510
172183.1.86.0/23183.1.86.1 to 183.1.87.254183.1.87.255510
173183.1.88.0/23183.1.88.1 to 183.1.89.254183.1.89.255510
174183.1.90.0/23183.1.90.1 to 183.1.91.254183.1.91.255510
175183.1.92.0/23183.1.92.1 to 183.1.93.254183.1.93.255510
176183.1.94.0/23183.1.94.1 to 183.1.95.254183.1.95.255510
177183.1.96.0/23183.1.96.1 to 183.1.97.254183.1.97.255510
178183.1.98.0/23183.1.98.1 to 183.1.99.254183.1.99.255510
179183.1.100.0/23183.1.100.1 to 183.1.101.254183.1.101.255510
180183.1.102.0/23183.1.102.1 to 183.1.103.254183.1.103.255510
181183.1.104.0/23183.1.104.1 to 183.1.105.254183.1.105.255510
182183.1.106.0/23183.1.106.1 to 183.1.107.254183.1.107.255510
183183.1.108.0/23183.1.108.1 to 183.1.109.254183.1.109.255510
184183.1.110.0/23183.1.110.1 to 183.1.111.254183.1.111.255510
185183.1.112.0/23183.1.112.1 to 183.1.113.254183.1.113.255510
186183.1.114.0/23183.1.114.1 to 183.1.115.254183.1.115.255510
187183.1.116.0/23183.1.116.1 to 183.1.117.254183.1.117.255510
188183.1.118.0/23183.1.118.1 to 183.1.119.254183.1.119.255510
189183.1.120.0/23183.1.120.1 to 183.1.121.254183.1.121.255510
190183.1.122.0/23183.1.122.1 to 183.1.123.254183.1.123.255510
191183.1.124.0/23183.1.124.1 to 183.1.125.254183.1.125.255510
192183.1.126.0/23183.1.126.1 to 183.1.127.254183.1.127.255510
193183.1.128.0/23183.1.128.1 to 183.1.129.254183.1.129.255510
194183.1.130.0/23183.1.130.1 to 183.1.131.254183.1.131.255510
195183.1.132.0/23183.1.132.1 to 183.1.133.254183.1.133.255510
196183.1.134.0/23183.1.134.1 to 183.1.135.254183.1.135.255510
197183.1.136.0/23183.1.136.1 to 183.1.137.254183.1.137.255510
198183.1.138.0/23183.1.138.1 to 183.1.139.254183.1.139.255510
199183.1.140.0/23183.1.140.1 to 183.1.141.254183.1.141.255510
200183.1.142.0/23183.1.142.1 to 183.1.143.254183.1.143.255510
201183.1.144.0/23183.1.144.1 to 183.1.145.254183.1.145.255510
202183.1.146.0/23183.1.146.1 to 183.1.147.254183.1.147.255510
203183.1.148.0/23183.1.148.1 to 183.1.149.254183.1.149.255510
204183.1.150.0/23183.1.150.1 to 183.1.151.254183.1.151.255510
205183.1.152.0/23183.1.152.1 to 183.1.153.254183.1.153.255510
206183.1.154.0/23183.1.154.1 to 183.1.155.254183.1.155.255510
207183.1.156.0/23183.1.156.1 to 183.1.157.254183.1.157.255510
208183.1.158.0/23183.1.158.1 to 183.1.159.254183.1.159.255510
209183.1.160.0/23183.1.160.1 to 183.1.161.254183.1.161.255510
210183.1.162.0/23183.1.162.1 to 183.1.163.254183.1.163.255510
211183.1.164.0/23183.1.164.1 to 183.1.165.254183.1.165.255510
212183.1.166.0/23183.1.166.1 to 183.1.167.254183.1.167.255510
213183.1.168.0/23183.1.168.1 to 183.1.169.254183.1.169.255510
214183.1.170.0/23183.1.170.1 to 183.1.171.254183.1.171.255510
215183.1.172.0/23183.1.172.1 to 183.1.173.254183.1.173.255510
216183.1.174.0/23183.1.174.1 to 183.1.175.254183.1.175.255510
217183.1.176.0/23183.1.176.1 to 183.1.177.254183.1.177.255510
218183.1.178.0/23183.1.178.1 to 183.1.179.254183.1.179.255510
219183.1.180.0/23183.1.180.1 to 183.1.181.254183.1.181.255510
220183.1.182.0/23183.1.182.1 to 183.1.183.254183.1.183.255510
221183.1.184.0/23183.1.184.1 to 183.1.185.254183.1.185.255510
222183.1.186.0/23183.1.186.1 to 183.1.187.254183.1.187.255510
223183.1.188.0/23183.1.188.1 to 183.1.189.254183.1.189.255510
224183.1.190.0/23183.1.190.1 to 183.1.191.254183.1.191.255510
225183.1.192.0/23183.1.192.1 to 183.1.193.254183.1.193.255510
226183.1.194.0/23183.1.194.1 to 183.1.195.254183.1.195.255510
227183.1.196.0/23183.1.196.1 to 183.1.197.254183.1.197.255510
228183.1.198.0/23183.1.198.1 to 183.1.199.254183.1.199.255510
229183.1.200.0/23183.1.200.1 to 183.1.201.254183.1.201.255510
230183.1.202.0/23183.1.202.1 to 183.1.203.254183.1.203.255510
231183.1.204.0/23183.1.204.1 to 183.1.205.254183.1.205.255510
232183.1.206.0/23183.1.206.1 to 183.1.207.254183.1.207.255510
233183.1.208.0/23183.1.208.1 to 183.1.209.254183.1.209.255510
234183.1.210.0/23183.1.210.1 to 183.1.211.254183.1.211.255510
235183.1.212.0/23183.1.212.1 to 183.1.213.254183.1.213.255510
236183.1.214.0/23183.1.214.1 to 183.1.215.254183.1.215.255510
237183.1.216.0/23183.1.216.1 to 183.1.217.254183.1.217.255510
238183.1.218.0/23183.1.218.1 to 183.1.219.254183.1.219.255510
239183.1.220.0/23183.1.220.1 to 183.1.221.254183.1.221.255510
240183.1.222.0/23183.1.222.1 to 183.1.223.254183.1.223.255510
241183.1.224.0/23183.1.224.1 to 183.1.225.254183.1.225.255510
242183.1.226.0/23183.1.226.1 to 183.1.227.254183.1.227.255510
243183.1.228.0/23183.1.228.1 to 183.1.229.254183.1.229.255510
244183.1.230.0/23183.1.230.1 to 183.1.231.254183.1.231.255510
245183.1.232.0/23183.1.232.1 to 183.1.233.254183.1.233.255510
246183.1.234.0/23183.1.234.1 to 183.1.235.254183.1.235.255510
247183.1.236.0/23183.1.236.1 to 183.1.237.254183.1.237.255510
248183.1.238.0/23183.1.238.1 to 183.1.239.254183.1.239.255510
249183.1.240.0/23183.1.240.1 to 183.1.241.254183.1.241.255510
250183.1.242.0/23183.1.242.1 to 183.1.243.254183.1.243.255510
251183.1.244.0/23183.1.244.1 to 183.1.245.254183.1.245.255510
252183.1.246.0/23183.1.246.1 to 183.1.247.254183.1.247.255510
253183.1.248.0/23183.1.248.1 to 183.1.249.254183.1.249.255510
254183.1.250.0/23183.1.250.1 to 183.1.251.254183.1.251.255510
255183.1.252.0/23183.1.252.1 to 183.1.253.254183.1.253.255510
256183.1.254.0/23183.1.254.1 to 183.1.255.254183.1.255.255510

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.