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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.

Network172.16.0.0/12
Usable hosts1,048,574
Subnet mask255.240.0.0
Addresses1,048,576
Network address
172.16.0.0
Broadcast address
172.31.255.255
First usable
172.16.0.1
Last usable
172.31.255.254
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
Private (RFC 1918) 172.16.0.0/12
Office and home networks; not routed on the internet
Old class
B (default /16)
As numbers
Hex AC100000 · Integer 2886729728 to 2887778303
Reverse DNS zones
16.172.in-addr.arpa
17.172.in-addr.arpa
18.172.in-addr.arpa
19.172.in-addr.arpa
20.172.in-addr.arpa
21.172.in-addr.arpa
22.172.in-addr.arpa
23.172.in-addr.arpa
24.172.in-addr.arpa
25.172.in-addr.arpa
26.172.in-addr.arpa
27.172.in-addr.arpa
28.172.in-addr.arpa
29.172.in-addr.arpa
30.172.in-addr.arpa
31.172.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
Address10101100.00010000.00000000.00000000172.16.0.0
Subnet mask11111111.11110000.00000000.00000000255.240.0.0
Network10101100.00010000.00000000.00000000172.16.0.0
Broadcast10101100.00011111.11111111.11111111172.31.255.255
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)

172.16.0.0/12 makes 2,048 subnets of /23; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1172.16.0.0/23172.16.0.1 to 172.16.1.254172.16.1.255510
2172.16.2.0/23172.16.2.1 to 172.16.3.254172.16.3.255510
3172.16.4.0/23172.16.4.1 to 172.16.5.254172.16.5.255510
4172.16.6.0/23172.16.6.1 to 172.16.7.254172.16.7.255510
5172.16.8.0/23172.16.8.1 to 172.16.9.254172.16.9.255510
6172.16.10.0/23172.16.10.1 to 172.16.11.254172.16.11.255510
7172.16.12.0/23172.16.12.1 to 172.16.13.254172.16.13.255510
8172.16.14.0/23172.16.14.1 to 172.16.15.254172.16.15.255510
9172.16.16.0/23172.16.16.1 to 172.16.17.254172.16.17.255510
10172.16.18.0/23172.16.18.1 to 172.16.19.254172.16.19.255510
11172.16.20.0/23172.16.20.1 to 172.16.21.254172.16.21.255510
12172.16.22.0/23172.16.22.1 to 172.16.23.254172.16.23.255510
13172.16.24.0/23172.16.24.1 to 172.16.25.254172.16.25.255510
14172.16.26.0/23172.16.26.1 to 172.16.27.254172.16.27.255510
15172.16.28.0/23172.16.28.1 to 172.16.29.254172.16.29.255510
16172.16.30.0/23172.16.30.1 to 172.16.31.254172.16.31.255510
17172.16.32.0/23172.16.32.1 to 172.16.33.254172.16.33.255510
18172.16.34.0/23172.16.34.1 to 172.16.35.254172.16.35.255510
19172.16.36.0/23172.16.36.1 to 172.16.37.254172.16.37.255510
20172.16.38.0/23172.16.38.1 to 172.16.39.254172.16.39.255510
21172.16.40.0/23172.16.40.1 to 172.16.41.254172.16.41.255510
22172.16.42.0/23172.16.42.1 to 172.16.43.254172.16.43.255510
23172.16.44.0/23172.16.44.1 to 172.16.45.254172.16.45.255510
24172.16.46.0/23172.16.46.1 to 172.16.47.254172.16.47.255510
25172.16.48.0/23172.16.48.1 to 172.16.49.254172.16.49.255510
26172.16.50.0/23172.16.50.1 to 172.16.51.254172.16.51.255510
27172.16.52.0/23172.16.52.1 to 172.16.53.254172.16.53.255510
28172.16.54.0/23172.16.54.1 to 172.16.55.254172.16.55.255510
29172.16.56.0/23172.16.56.1 to 172.16.57.254172.16.57.255510
30172.16.58.0/23172.16.58.1 to 172.16.59.254172.16.59.255510
31172.16.60.0/23172.16.60.1 to 172.16.61.254172.16.61.255510
32172.16.62.0/23172.16.62.1 to 172.16.63.254172.16.63.255510
33172.16.64.0/23172.16.64.1 to 172.16.65.254172.16.65.255510
34172.16.66.0/23172.16.66.1 to 172.16.67.254172.16.67.255510
35172.16.68.0/23172.16.68.1 to 172.16.69.254172.16.69.255510
36172.16.70.0/23172.16.70.1 to 172.16.71.254172.16.71.255510
37172.16.72.0/23172.16.72.1 to 172.16.73.254172.16.73.255510
38172.16.74.0/23172.16.74.1 to 172.16.75.254172.16.75.255510
39172.16.76.0/23172.16.76.1 to 172.16.77.254172.16.77.255510
40172.16.78.0/23172.16.78.1 to 172.16.79.254172.16.79.255510
41172.16.80.0/23172.16.80.1 to 172.16.81.254172.16.81.255510
42172.16.82.0/23172.16.82.1 to 172.16.83.254172.16.83.255510
43172.16.84.0/23172.16.84.1 to 172.16.85.254172.16.85.255510
44172.16.86.0/23172.16.86.1 to 172.16.87.254172.16.87.255510
45172.16.88.0/23172.16.88.1 to 172.16.89.254172.16.89.255510
46172.16.90.0/23172.16.90.1 to 172.16.91.254172.16.91.255510
47172.16.92.0/23172.16.92.1 to 172.16.93.254172.16.93.255510
48172.16.94.0/23172.16.94.1 to 172.16.95.254172.16.95.255510
49172.16.96.0/23172.16.96.1 to 172.16.97.254172.16.97.255510
50172.16.98.0/23172.16.98.1 to 172.16.99.254172.16.99.255510
51172.16.100.0/23172.16.100.1 to 172.16.101.254172.16.101.255510
52172.16.102.0/23172.16.102.1 to 172.16.103.254172.16.103.255510
53172.16.104.0/23172.16.104.1 to 172.16.105.254172.16.105.255510
54172.16.106.0/23172.16.106.1 to 172.16.107.254172.16.107.255510
55172.16.108.0/23172.16.108.1 to 172.16.109.254172.16.109.255510
56172.16.110.0/23172.16.110.1 to 172.16.111.254172.16.111.255510
57172.16.112.0/23172.16.112.1 to 172.16.113.254172.16.113.255510
58172.16.114.0/23172.16.114.1 to 172.16.115.254172.16.115.255510
59172.16.116.0/23172.16.116.1 to 172.16.117.254172.16.117.255510
60172.16.118.0/23172.16.118.1 to 172.16.119.254172.16.119.255510
61172.16.120.0/23172.16.120.1 to 172.16.121.254172.16.121.255510
62172.16.122.0/23172.16.122.1 to 172.16.123.254172.16.123.255510
63172.16.124.0/23172.16.124.1 to 172.16.125.254172.16.125.255510
64172.16.126.0/23172.16.126.1 to 172.16.127.254172.16.127.255510
65172.16.128.0/23172.16.128.1 to 172.16.129.254172.16.129.255510
66172.16.130.0/23172.16.130.1 to 172.16.131.254172.16.131.255510
67172.16.132.0/23172.16.132.1 to 172.16.133.254172.16.133.255510
68172.16.134.0/23172.16.134.1 to 172.16.135.254172.16.135.255510
69172.16.136.0/23172.16.136.1 to 172.16.137.254172.16.137.255510
70172.16.138.0/23172.16.138.1 to 172.16.139.254172.16.139.255510
71172.16.140.0/23172.16.140.1 to 172.16.141.254172.16.141.255510
72172.16.142.0/23172.16.142.1 to 172.16.143.254172.16.143.255510
73172.16.144.0/23172.16.144.1 to 172.16.145.254172.16.145.255510
74172.16.146.0/23172.16.146.1 to 172.16.147.254172.16.147.255510
75172.16.148.0/23172.16.148.1 to 172.16.149.254172.16.149.255510
76172.16.150.0/23172.16.150.1 to 172.16.151.254172.16.151.255510
77172.16.152.0/23172.16.152.1 to 172.16.153.254172.16.153.255510
78172.16.154.0/23172.16.154.1 to 172.16.155.254172.16.155.255510
79172.16.156.0/23172.16.156.1 to 172.16.157.254172.16.157.255510
80172.16.158.0/23172.16.158.1 to 172.16.159.254172.16.159.255510
81172.16.160.0/23172.16.160.1 to 172.16.161.254172.16.161.255510
82172.16.162.0/23172.16.162.1 to 172.16.163.254172.16.163.255510
83172.16.164.0/23172.16.164.1 to 172.16.165.254172.16.165.255510
84172.16.166.0/23172.16.166.1 to 172.16.167.254172.16.167.255510
85172.16.168.0/23172.16.168.1 to 172.16.169.254172.16.169.255510
86172.16.170.0/23172.16.170.1 to 172.16.171.254172.16.171.255510
87172.16.172.0/23172.16.172.1 to 172.16.173.254172.16.173.255510
88172.16.174.0/23172.16.174.1 to 172.16.175.254172.16.175.255510
89172.16.176.0/23172.16.176.1 to 172.16.177.254172.16.177.255510
90172.16.178.0/23172.16.178.1 to 172.16.179.254172.16.179.255510
91172.16.180.0/23172.16.180.1 to 172.16.181.254172.16.181.255510
92172.16.182.0/23172.16.182.1 to 172.16.183.254172.16.183.255510
93172.16.184.0/23172.16.184.1 to 172.16.185.254172.16.185.255510
94172.16.186.0/23172.16.186.1 to 172.16.187.254172.16.187.255510
95172.16.188.0/23172.16.188.1 to 172.16.189.254172.16.189.255510
96172.16.190.0/23172.16.190.1 to 172.16.191.254172.16.191.255510
97172.16.192.0/23172.16.192.1 to 172.16.193.254172.16.193.255510
98172.16.194.0/23172.16.194.1 to 172.16.195.254172.16.195.255510
99172.16.196.0/23172.16.196.1 to 172.16.197.254172.16.197.255510
100172.16.198.0/23172.16.198.1 to 172.16.199.254172.16.199.255510
101172.16.200.0/23172.16.200.1 to 172.16.201.254172.16.201.255510
102172.16.202.0/23172.16.202.1 to 172.16.203.254172.16.203.255510
103172.16.204.0/23172.16.204.1 to 172.16.205.254172.16.205.255510
104172.16.206.0/23172.16.206.1 to 172.16.207.254172.16.207.255510
105172.16.208.0/23172.16.208.1 to 172.16.209.254172.16.209.255510
106172.16.210.0/23172.16.210.1 to 172.16.211.254172.16.211.255510
107172.16.212.0/23172.16.212.1 to 172.16.213.254172.16.213.255510
108172.16.214.0/23172.16.214.1 to 172.16.215.254172.16.215.255510
109172.16.216.0/23172.16.216.1 to 172.16.217.254172.16.217.255510
110172.16.218.0/23172.16.218.1 to 172.16.219.254172.16.219.255510
111172.16.220.0/23172.16.220.1 to 172.16.221.254172.16.221.255510
112172.16.222.0/23172.16.222.1 to 172.16.223.254172.16.223.255510
113172.16.224.0/23172.16.224.1 to 172.16.225.254172.16.225.255510
114172.16.226.0/23172.16.226.1 to 172.16.227.254172.16.227.255510
115172.16.228.0/23172.16.228.1 to 172.16.229.254172.16.229.255510
116172.16.230.0/23172.16.230.1 to 172.16.231.254172.16.231.255510
117172.16.232.0/23172.16.232.1 to 172.16.233.254172.16.233.255510
118172.16.234.0/23172.16.234.1 to 172.16.235.254172.16.235.255510
119172.16.236.0/23172.16.236.1 to 172.16.237.254172.16.237.255510
120172.16.238.0/23172.16.238.1 to 172.16.239.254172.16.239.255510
121172.16.240.0/23172.16.240.1 to 172.16.241.254172.16.241.255510
122172.16.242.0/23172.16.242.1 to 172.16.243.254172.16.243.255510
123172.16.244.0/23172.16.244.1 to 172.16.245.254172.16.245.255510
124172.16.246.0/23172.16.246.1 to 172.16.247.254172.16.247.255510
125172.16.248.0/23172.16.248.1 to 172.16.249.254172.16.249.255510
126172.16.250.0/23172.16.250.1 to 172.16.251.254172.16.251.255510
127172.16.252.0/23172.16.252.1 to 172.16.253.254172.16.253.255510
128172.16.254.0/23172.16.254.1 to 172.16.255.254172.16.255.255510
129172.17.0.0/23172.17.0.1 to 172.17.1.254172.17.1.255510
130172.17.2.0/23172.17.2.1 to 172.17.3.254172.17.3.255510
131172.17.4.0/23172.17.4.1 to 172.17.5.254172.17.5.255510
132172.17.6.0/23172.17.6.1 to 172.17.7.254172.17.7.255510
133172.17.8.0/23172.17.8.1 to 172.17.9.254172.17.9.255510
134172.17.10.0/23172.17.10.1 to 172.17.11.254172.17.11.255510
135172.17.12.0/23172.17.12.1 to 172.17.13.254172.17.13.255510
136172.17.14.0/23172.17.14.1 to 172.17.15.254172.17.15.255510
137172.17.16.0/23172.17.16.1 to 172.17.17.254172.17.17.255510
138172.17.18.0/23172.17.18.1 to 172.17.19.254172.17.19.255510
139172.17.20.0/23172.17.20.1 to 172.17.21.254172.17.21.255510
140172.17.22.0/23172.17.22.1 to 172.17.23.254172.17.23.255510
141172.17.24.0/23172.17.24.1 to 172.17.25.254172.17.25.255510
142172.17.26.0/23172.17.26.1 to 172.17.27.254172.17.27.255510
143172.17.28.0/23172.17.28.1 to 172.17.29.254172.17.29.255510
144172.17.30.0/23172.17.30.1 to 172.17.31.254172.17.31.255510
145172.17.32.0/23172.17.32.1 to 172.17.33.254172.17.33.255510
146172.17.34.0/23172.17.34.1 to 172.17.35.254172.17.35.255510
147172.17.36.0/23172.17.36.1 to 172.17.37.254172.17.37.255510
148172.17.38.0/23172.17.38.1 to 172.17.39.254172.17.39.255510
149172.17.40.0/23172.17.40.1 to 172.17.41.254172.17.41.255510
150172.17.42.0/23172.17.42.1 to 172.17.43.254172.17.43.255510
151172.17.44.0/23172.17.44.1 to 172.17.45.254172.17.45.255510
152172.17.46.0/23172.17.46.1 to 172.17.47.254172.17.47.255510
153172.17.48.0/23172.17.48.1 to 172.17.49.254172.17.49.255510
154172.17.50.0/23172.17.50.1 to 172.17.51.254172.17.51.255510
155172.17.52.0/23172.17.52.1 to 172.17.53.254172.17.53.255510
156172.17.54.0/23172.17.54.1 to 172.17.55.254172.17.55.255510
157172.17.56.0/23172.17.56.1 to 172.17.57.254172.17.57.255510
158172.17.58.0/23172.17.58.1 to 172.17.59.254172.17.59.255510
159172.17.60.0/23172.17.60.1 to 172.17.61.254172.17.61.255510
160172.17.62.0/23172.17.62.1 to 172.17.63.254172.17.63.255510
161172.17.64.0/23172.17.64.1 to 172.17.65.254172.17.65.255510
162172.17.66.0/23172.17.66.1 to 172.17.67.254172.17.67.255510
163172.17.68.0/23172.17.68.1 to 172.17.69.254172.17.69.255510
164172.17.70.0/23172.17.70.1 to 172.17.71.254172.17.71.255510
165172.17.72.0/23172.17.72.1 to 172.17.73.254172.17.73.255510
166172.17.74.0/23172.17.74.1 to 172.17.75.254172.17.75.255510
167172.17.76.0/23172.17.76.1 to 172.17.77.254172.17.77.255510
168172.17.78.0/23172.17.78.1 to 172.17.79.254172.17.79.255510
169172.17.80.0/23172.17.80.1 to 172.17.81.254172.17.81.255510
170172.17.82.0/23172.17.82.1 to 172.17.83.254172.17.83.255510
171172.17.84.0/23172.17.84.1 to 172.17.85.254172.17.85.255510
172172.17.86.0/23172.17.86.1 to 172.17.87.254172.17.87.255510
173172.17.88.0/23172.17.88.1 to 172.17.89.254172.17.89.255510
174172.17.90.0/23172.17.90.1 to 172.17.91.254172.17.91.255510
175172.17.92.0/23172.17.92.1 to 172.17.93.254172.17.93.255510
176172.17.94.0/23172.17.94.1 to 172.17.95.254172.17.95.255510
177172.17.96.0/23172.17.96.1 to 172.17.97.254172.17.97.255510
178172.17.98.0/23172.17.98.1 to 172.17.99.254172.17.99.255510
179172.17.100.0/23172.17.100.1 to 172.17.101.254172.17.101.255510
180172.17.102.0/23172.17.102.1 to 172.17.103.254172.17.103.255510
181172.17.104.0/23172.17.104.1 to 172.17.105.254172.17.105.255510
182172.17.106.0/23172.17.106.1 to 172.17.107.254172.17.107.255510
183172.17.108.0/23172.17.108.1 to 172.17.109.254172.17.109.255510
184172.17.110.0/23172.17.110.1 to 172.17.111.254172.17.111.255510
185172.17.112.0/23172.17.112.1 to 172.17.113.254172.17.113.255510
186172.17.114.0/23172.17.114.1 to 172.17.115.254172.17.115.255510
187172.17.116.0/23172.17.116.1 to 172.17.117.254172.17.117.255510
188172.17.118.0/23172.17.118.1 to 172.17.119.254172.17.119.255510
189172.17.120.0/23172.17.120.1 to 172.17.121.254172.17.121.255510
190172.17.122.0/23172.17.122.1 to 172.17.123.254172.17.123.255510
191172.17.124.0/23172.17.124.1 to 172.17.125.254172.17.125.255510
192172.17.126.0/23172.17.126.1 to 172.17.127.254172.17.127.255510
193172.17.128.0/23172.17.128.1 to 172.17.129.254172.17.129.255510
194172.17.130.0/23172.17.130.1 to 172.17.131.254172.17.131.255510
195172.17.132.0/23172.17.132.1 to 172.17.133.254172.17.133.255510
196172.17.134.0/23172.17.134.1 to 172.17.135.254172.17.135.255510
197172.17.136.0/23172.17.136.1 to 172.17.137.254172.17.137.255510
198172.17.138.0/23172.17.138.1 to 172.17.139.254172.17.139.255510
199172.17.140.0/23172.17.140.1 to 172.17.141.254172.17.141.255510
200172.17.142.0/23172.17.142.1 to 172.17.143.254172.17.143.255510
201172.17.144.0/23172.17.144.1 to 172.17.145.254172.17.145.255510
202172.17.146.0/23172.17.146.1 to 172.17.147.254172.17.147.255510
203172.17.148.0/23172.17.148.1 to 172.17.149.254172.17.149.255510
204172.17.150.0/23172.17.150.1 to 172.17.151.254172.17.151.255510
205172.17.152.0/23172.17.152.1 to 172.17.153.254172.17.153.255510
206172.17.154.0/23172.17.154.1 to 172.17.155.254172.17.155.255510
207172.17.156.0/23172.17.156.1 to 172.17.157.254172.17.157.255510
208172.17.158.0/23172.17.158.1 to 172.17.159.254172.17.159.255510
209172.17.160.0/23172.17.160.1 to 172.17.161.254172.17.161.255510
210172.17.162.0/23172.17.162.1 to 172.17.163.254172.17.163.255510
211172.17.164.0/23172.17.164.1 to 172.17.165.254172.17.165.255510
212172.17.166.0/23172.17.166.1 to 172.17.167.254172.17.167.255510
213172.17.168.0/23172.17.168.1 to 172.17.169.254172.17.169.255510
214172.17.170.0/23172.17.170.1 to 172.17.171.254172.17.171.255510
215172.17.172.0/23172.17.172.1 to 172.17.173.254172.17.173.255510
216172.17.174.0/23172.17.174.1 to 172.17.175.254172.17.175.255510
217172.17.176.0/23172.17.176.1 to 172.17.177.254172.17.177.255510
218172.17.178.0/23172.17.178.1 to 172.17.179.254172.17.179.255510
219172.17.180.0/23172.17.180.1 to 172.17.181.254172.17.181.255510
220172.17.182.0/23172.17.182.1 to 172.17.183.254172.17.183.255510
221172.17.184.0/23172.17.184.1 to 172.17.185.254172.17.185.255510
222172.17.186.0/23172.17.186.1 to 172.17.187.254172.17.187.255510
223172.17.188.0/23172.17.188.1 to 172.17.189.254172.17.189.255510
224172.17.190.0/23172.17.190.1 to 172.17.191.254172.17.191.255510
225172.17.192.0/23172.17.192.1 to 172.17.193.254172.17.193.255510
226172.17.194.0/23172.17.194.1 to 172.17.195.254172.17.195.255510
227172.17.196.0/23172.17.196.1 to 172.17.197.254172.17.197.255510
228172.17.198.0/23172.17.198.1 to 172.17.199.254172.17.199.255510
229172.17.200.0/23172.17.200.1 to 172.17.201.254172.17.201.255510
230172.17.202.0/23172.17.202.1 to 172.17.203.254172.17.203.255510
231172.17.204.0/23172.17.204.1 to 172.17.205.254172.17.205.255510
232172.17.206.0/23172.17.206.1 to 172.17.207.254172.17.207.255510
233172.17.208.0/23172.17.208.1 to 172.17.209.254172.17.209.255510
234172.17.210.0/23172.17.210.1 to 172.17.211.254172.17.211.255510
235172.17.212.0/23172.17.212.1 to 172.17.213.254172.17.213.255510
236172.17.214.0/23172.17.214.1 to 172.17.215.254172.17.215.255510
237172.17.216.0/23172.17.216.1 to 172.17.217.254172.17.217.255510
238172.17.218.0/23172.17.218.1 to 172.17.219.254172.17.219.255510
239172.17.220.0/23172.17.220.1 to 172.17.221.254172.17.221.255510
240172.17.222.0/23172.17.222.1 to 172.17.223.254172.17.223.255510
241172.17.224.0/23172.17.224.1 to 172.17.225.254172.17.225.255510
242172.17.226.0/23172.17.226.1 to 172.17.227.254172.17.227.255510
243172.17.228.0/23172.17.228.1 to 172.17.229.254172.17.229.255510
244172.17.230.0/23172.17.230.1 to 172.17.231.254172.17.231.255510
245172.17.232.0/23172.17.232.1 to 172.17.233.254172.17.233.255510
246172.17.234.0/23172.17.234.1 to 172.17.235.254172.17.235.255510
247172.17.236.0/23172.17.236.1 to 172.17.237.254172.17.237.255510
248172.17.238.0/23172.17.238.1 to 172.17.239.254172.17.239.255510
249172.17.240.0/23172.17.240.1 to 172.17.241.254172.17.241.255510
250172.17.242.0/23172.17.242.1 to 172.17.243.254172.17.243.255510
251172.17.244.0/23172.17.244.1 to 172.17.245.254172.17.245.255510
252172.17.246.0/23172.17.246.1 to 172.17.247.254172.17.247.255510
253172.17.248.0/23172.17.248.1 to 172.17.249.254172.17.249.255510
254172.17.250.0/23172.17.250.1 to 172.17.251.254172.17.251.255510
255172.17.252.0/23172.17.252.1 to 172.17.253.254172.17.253.255510
256172.17.254.0/23172.17.254.1 to 172.17.255.254172.17.255.255510

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.