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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/22
/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 1,024 subnets of /22; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1172.16.0.0/22172.16.0.1 to 172.16.3.254172.16.3.2551,022
2172.16.4.0/22172.16.4.1 to 172.16.7.254172.16.7.2551,022
3172.16.8.0/22172.16.8.1 to 172.16.11.254172.16.11.2551,022
4172.16.12.0/22172.16.12.1 to 172.16.15.254172.16.15.2551,022
5172.16.16.0/22172.16.16.1 to 172.16.19.254172.16.19.2551,022
6172.16.20.0/22172.16.20.1 to 172.16.23.254172.16.23.2551,022
7172.16.24.0/22172.16.24.1 to 172.16.27.254172.16.27.2551,022
8172.16.28.0/22172.16.28.1 to 172.16.31.254172.16.31.2551,022
9172.16.32.0/22172.16.32.1 to 172.16.35.254172.16.35.2551,022
10172.16.36.0/22172.16.36.1 to 172.16.39.254172.16.39.2551,022
11172.16.40.0/22172.16.40.1 to 172.16.43.254172.16.43.2551,022
12172.16.44.0/22172.16.44.1 to 172.16.47.254172.16.47.2551,022
13172.16.48.0/22172.16.48.1 to 172.16.51.254172.16.51.2551,022
14172.16.52.0/22172.16.52.1 to 172.16.55.254172.16.55.2551,022
15172.16.56.0/22172.16.56.1 to 172.16.59.254172.16.59.2551,022
16172.16.60.0/22172.16.60.1 to 172.16.63.254172.16.63.2551,022
17172.16.64.0/22172.16.64.1 to 172.16.67.254172.16.67.2551,022
18172.16.68.0/22172.16.68.1 to 172.16.71.254172.16.71.2551,022
19172.16.72.0/22172.16.72.1 to 172.16.75.254172.16.75.2551,022
20172.16.76.0/22172.16.76.1 to 172.16.79.254172.16.79.2551,022
21172.16.80.0/22172.16.80.1 to 172.16.83.254172.16.83.2551,022
22172.16.84.0/22172.16.84.1 to 172.16.87.254172.16.87.2551,022
23172.16.88.0/22172.16.88.1 to 172.16.91.254172.16.91.2551,022
24172.16.92.0/22172.16.92.1 to 172.16.95.254172.16.95.2551,022
25172.16.96.0/22172.16.96.1 to 172.16.99.254172.16.99.2551,022
26172.16.100.0/22172.16.100.1 to 172.16.103.254172.16.103.2551,022
27172.16.104.0/22172.16.104.1 to 172.16.107.254172.16.107.2551,022
28172.16.108.0/22172.16.108.1 to 172.16.111.254172.16.111.2551,022
29172.16.112.0/22172.16.112.1 to 172.16.115.254172.16.115.2551,022
30172.16.116.0/22172.16.116.1 to 172.16.119.254172.16.119.2551,022
31172.16.120.0/22172.16.120.1 to 172.16.123.254172.16.123.2551,022
32172.16.124.0/22172.16.124.1 to 172.16.127.254172.16.127.2551,022
33172.16.128.0/22172.16.128.1 to 172.16.131.254172.16.131.2551,022
34172.16.132.0/22172.16.132.1 to 172.16.135.254172.16.135.2551,022
35172.16.136.0/22172.16.136.1 to 172.16.139.254172.16.139.2551,022
36172.16.140.0/22172.16.140.1 to 172.16.143.254172.16.143.2551,022
37172.16.144.0/22172.16.144.1 to 172.16.147.254172.16.147.2551,022
38172.16.148.0/22172.16.148.1 to 172.16.151.254172.16.151.2551,022
39172.16.152.0/22172.16.152.1 to 172.16.155.254172.16.155.2551,022
40172.16.156.0/22172.16.156.1 to 172.16.159.254172.16.159.2551,022
41172.16.160.0/22172.16.160.1 to 172.16.163.254172.16.163.2551,022
42172.16.164.0/22172.16.164.1 to 172.16.167.254172.16.167.2551,022
43172.16.168.0/22172.16.168.1 to 172.16.171.254172.16.171.2551,022
44172.16.172.0/22172.16.172.1 to 172.16.175.254172.16.175.2551,022
45172.16.176.0/22172.16.176.1 to 172.16.179.254172.16.179.2551,022
46172.16.180.0/22172.16.180.1 to 172.16.183.254172.16.183.2551,022
47172.16.184.0/22172.16.184.1 to 172.16.187.254172.16.187.2551,022
48172.16.188.0/22172.16.188.1 to 172.16.191.254172.16.191.2551,022
49172.16.192.0/22172.16.192.1 to 172.16.195.254172.16.195.2551,022
50172.16.196.0/22172.16.196.1 to 172.16.199.254172.16.199.2551,022
51172.16.200.0/22172.16.200.1 to 172.16.203.254172.16.203.2551,022
52172.16.204.0/22172.16.204.1 to 172.16.207.254172.16.207.2551,022
53172.16.208.0/22172.16.208.1 to 172.16.211.254172.16.211.2551,022
54172.16.212.0/22172.16.212.1 to 172.16.215.254172.16.215.2551,022
55172.16.216.0/22172.16.216.1 to 172.16.219.254172.16.219.2551,022
56172.16.220.0/22172.16.220.1 to 172.16.223.254172.16.223.2551,022
57172.16.224.0/22172.16.224.1 to 172.16.227.254172.16.227.2551,022
58172.16.228.0/22172.16.228.1 to 172.16.231.254172.16.231.2551,022
59172.16.232.0/22172.16.232.1 to 172.16.235.254172.16.235.2551,022
60172.16.236.0/22172.16.236.1 to 172.16.239.254172.16.239.2551,022
61172.16.240.0/22172.16.240.1 to 172.16.243.254172.16.243.2551,022
62172.16.244.0/22172.16.244.1 to 172.16.247.254172.16.247.2551,022
63172.16.248.0/22172.16.248.1 to 172.16.251.254172.16.251.2551,022
64172.16.252.0/22172.16.252.1 to 172.16.255.254172.16.255.2551,022
65172.17.0.0/22172.17.0.1 to 172.17.3.254172.17.3.2551,022
66172.17.4.0/22172.17.4.1 to 172.17.7.254172.17.7.2551,022
67172.17.8.0/22172.17.8.1 to 172.17.11.254172.17.11.2551,022
68172.17.12.0/22172.17.12.1 to 172.17.15.254172.17.15.2551,022
69172.17.16.0/22172.17.16.1 to 172.17.19.254172.17.19.2551,022
70172.17.20.0/22172.17.20.1 to 172.17.23.254172.17.23.2551,022
71172.17.24.0/22172.17.24.1 to 172.17.27.254172.17.27.2551,022
72172.17.28.0/22172.17.28.1 to 172.17.31.254172.17.31.2551,022
73172.17.32.0/22172.17.32.1 to 172.17.35.254172.17.35.2551,022
74172.17.36.0/22172.17.36.1 to 172.17.39.254172.17.39.2551,022
75172.17.40.0/22172.17.40.1 to 172.17.43.254172.17.43.2551,022
76172.17.44.0/22172.17.44.1 to 172.17.47.254172.17.47.2551,022
77172.17.48.0/22172.17.48.1 to 172.17.51.254172.17.51.2551,022
78172.17.52.0/22172.17.52.1 to 172.17.55.254172.17.55.2551,022
79172.17.56.0/22172.17.56.1 to 172.17.59.254172.17.59.2551,022
80172.17.60.0/22172.17.60.1 to 172.17.63.254172.17.63.2551,022
81172.17.64.0/22172.17.64.1 to 172.17.67.254172.17.67.2551,022
82172.17.68.0/22172.17.68.1 to 172.17.71.254172.17.71.2551,022
83172.17.72.0/22172.17.72.1 to 172.17.75.254172.17.75.2551,022
84172.17.76.0/22172.17.76.1 to 172.17.79.254172.17.79.2551,022
85172.17.80.0/22172.17.80.1 to 172.17.83.254172.17.83.2551,022
86172.17.84.0/22172.17.84.1 to 172.17.87.254172.17.87.2551,022
87172.17.88.0/22172.17.88.1 to 172.17.91.254172.17.91.2551,022
88172.17.92.0/22172.17.92.1 to 172.17.95.254172.17.95.2551,022
89172.17.96.0/22172.17.96.1 to 172.17.99.254172.17.99.2551,022
90172.17.100.0/22172.17.100.1 to 172.17.103.254172.17.103.2551,022
91172.17.104.0/22172.17.104.1 to 172.17.107.254172.17.107.2551,022
92172.17.108.0/22172.17.108.1 to 172.17.111.254172.17.111.2551,022
93172.17.112.0/22172.17.112.1 to 172.17.115.254172.17.115.2551,022
94172.17.116.0/22172.17.116.1 to 172.17.119.254172.17.119.2551,022
95172.17.120.0/22172.17.120.1 to 172.17.123.254172.17.123.2551,022
96172.17.124.0/22172.17.124.1 to 172.17.127.254172.17.127.2551,022
97172.17.128.0/22172.17.128.1 to 172.17.131.254172.17.131.2551,022
98172.17.132.0/22172.17.132.1 to 172.17.135.254172.17.135.2551,022
99172.17.136.0/22172.17.136.1 to 172.17.139.254172.17.139.2551,022
100172.17.140.0/22172.17.140.1 to 172.17.143.254172.17.143.2551,022
101172.17.144.0/22172.17.144.1 to 172.17.147.254172.17.147.2551,022
102172.17.148.0/22172.17.148.1 to 172.17.151.254172.17.151.2551,022
103172.17.152.0/22172.17.152.1 to 172.17.155.254172.17.155.2551,022
104172.17.156.0/22172.17.156.1 to 172.17.159.254172.17.159.2551,022
105172.17.160.0/22172.17.160.1 to 172.17.163.254172.17.163.2551,022
106172.17.164.0/22172.17.164.1 to 172.17.167.254172.17.167.2551,022
107172.17.168.0/22172.17.168.1 to 172.17.171.254172.17.171.2551,022
108172.17.172.0/22172.17.172.1 to 172.17.175.254172.17.175.2551,022
109172.17.176.0/22172.17.176.1 to 172.17.179.254172.17.179.2551,022
110172.17.180.0/22172.17.180.1 to 172.17.183.254172.17.183.2551,022
111172.17.184.0/22172.17.184.1 to 172.17.187.254172.17.187.2551,022
112172.17.188.0/22172.17.188.1 to 172.17.191.254172.17.191.2551,022
113172.17.192.0/22172.17.192.1 to 172.17.195.254172.17.195.2551,022
114172.17.196.0/22172.17.196.1 to 172.17.199.254172.17.199.2551,022
115172.17.200.0/22172.17.200.1 to 172.17.203.254172.17.203.2551,022
116172.17.204.0/22172.17.204.1 to 172.17.207.254172.17.207.2551,022
117172.17.208.0/22172.17.208.1 to 172.17.211.254172.17.211.2551,022
118172.17.212.0/22172.17.212.1 to 172.17.215.254172.17.215.2551,022
119172.17.216.0/22172.17.216.1 to 172.17.219.254172.17.219.2551,022
120172.17.220.0/22172.17.220.1 to 172.17.223.254172.17.223.2551,022
121172.17.224.0/22172.17.224.1 to 172.17.227.254172.17.227.2551,022
122172.17.228.0/22172.17.228.1 to 172.17.231.254172.17.231.2551,022
123172.17.232.0/22172.17.232.1 to 172.17.235.254172.17.235.2551,022
124172.17.236.0/22172.17.236.1 to 172.17.239.254172.17.239.2551,022
125172.17.240.0/22172.17.240.1 to 172.17.243.254172.17.243.2551,022
126172.17.244.0/22172.17.244.1 to 172.17.247.254172.17.247.2551,022
127172.17.248.0/22172.17.248.1 to 172.17.251.254172.17.251.2551,022
128172.17.252.0/22172.17.252.1 to 172.17.255.254172.17.255.2551,022
129172.18.0.0/22172.18.0.1 to 172.18.3.254172.18.3.2551,022
130172.18.4.0/22172.18.4.1 to 172.18.7.254172.18.7.2551,022
131172.18.8.0/22172.18.8.1 to 172.18.11.254172.18.11.2551,022
132172.18.12.0/22172.18.12.1 to 172.18.15.254172.18.15.2551,022
133172.18.16.0/22172.18.16.1 to 172.18.19.254172.18.19.2551,022
134172.18.20.0/22172.18.20.1 to 172.18.23.254172.18.23.2551,022
135172.18.24.0/22172.18.24.1 to 172.18.27.254172.18.27.2551,022
136172.18.28.0/22172.18.28.1 to 172.18.31.254172.18.31.2551,022
137172.18.32.0/22172.18.32.1 to 172.18.35.254172.18.35.2551,022
138172.18.36.0/22172.18.36.1 to 172.18.39.254172.18.39.2551,022
139172.18.40.0/22172.18.40.1 to 172.18.43.254172.18.43.2551,022
140172.18.44.0/22172.18.44.1 to 172.18.47.254172.18.47.2551,022
141172.18.48.0/22172.18.48.1 to 172.18.51.254172.18.51.2551,022
142172.18.52.0/22172.18.52.1 to 172.18.55.254172.18.55.2551,022
143172.18.56.0/22172.18.56.1 to 172.18.59.254172.18.59.2551,022
144172.18.60.0/22172.18.60.1 to 172.18.63.254172.18.63.2551,022
145172.18.64.0/22172.18.64.1 to 172.18.67.254172.18.67.2551,022
146172.18.68.0/22172.18.68.1 to 172.18.71.254172.18.71.2551,022
147172.18.72.0/22172.18.72.1 to 172.18.75.254172.18.75.2551,022
148172.18.76.0/22172.18.76.1 to 172.18.79.254172.18.79.2551,022
149172.18.80.0/22172.18.80.1 to 172.18.83.254172.18.83.2551,022
150172.18.84.0/22172.18.84.1 to 172.18.87.254172.18.87.2551,022
151172.18.88.0/22172.18.88.1 to 172.18.91.254172.18.91.2551,022
152172.18.92.0/22172.18.92.1 to 172.18.95.254172.18.95.2551,022
153172.18.96.0/22172.18.96.1 to 172.18.99.254172.18.99.2551,022
154172.18.100.0/22172.18.100.1 to 172.18.103.254172.18.103.2551,022
155172.18.104.0/22172.18.104.1 to 172.18.107.254172.18.107.2551,022
156172.18.108.0/22172.18.108.1 to 172.18.111.254172.18.111.2551,022
157172.18.112.0/22172.18.112.1 to 172.18.115.254172.18.115.2551,022
158172.18.116.0/22172.18.116.1 to 172.18.119.254172.18.119.2551,022
159172.18.120.0/22172.18.120.1 to 172.18.123.254172.18.123.2551,022
160172.18.124.0/22172.18.124.1 to 172.18.127.254172.18.127.2551,022
161172.18.128.0/22172.18.128.1 to 172.18.131.254172.18.131.2551,022
162172.18.132.0/22172.18.132.1 to 172.18.135.254172.18.135.2551,022
163172.18.136.0/22172.18.136.1 to 172.18.139.254172.18.139.2551,022
164172.18.140.0/22172.18.140.1 to 172.18.143.254172.18.143.2551,022
165172.18.144.0/22172.18.144.1 to 172.18.147.254172.18.147.2551,022
166172.18.148.0/22172.18.148.1 to 172.18.151.254172.18.151.2551,022
167172.18.152.0/22172.18.152.1 to 172.18.155.254172.18.155.2551,022
168172.18.156.0/22172.18.156.1 to 172.18.159.254172.18.159.2551,022
169172.18.160.0/22172.18.160.1 to 172.18.163.254172.18.163.2551,022
170172.18.164.0/22172.18.164.1 to 172.18.167.254172.18.167.2551,022
171172.18.168.0/22172.18.168.1 to 172.18.171.254172.18.171.2551,022
172172.18.172.0/22172.18.172.1 to 172.18.175.254172.18.175.2551,022
173172.18.176.0/22172.18.176.1 to 172.18.179.254172.18.179.2551,022
174172.18.180.0/22172.18.180.1 to 172.18.183.254172.18.183.2551,022
175172.18.184.0/22172.18.184.1 to 172.18.187.254172.18.187.2551,022
176172.18.188.0/22172.18.188.1 to 172.18.191.254172.18.191.2551,022
177172.18.192.0/22172.18.192.1 to 172.18.195.254172.18.195.2551,022
178172.18.196.0/22172.18.196.1 to 172.18.199.254172.18.199.2551,022
179172.18.200.0/22172.18.200.1 to 172.18.203.254172.18.203.2551,022
180172.18.204.0/22172.18.204.1 to 172.18.207.254172.18.207.2551,022
181172.18.208.0/22172.18.208.1 to 172.18.211.254172.18.211.2551,022
182172.18.212.0/22172.18.212.1 to 172.18.215.254172.18.215.2551,022
183172.18.216.0/22172.18.216.1 to 172.18.219.254172.18.219.2551,022
184172.18.220.0/22172.18.220.1 to 172.18.223.254172.18.223.2551,022
185172.18.224.0/22172.18.224.1 to 172.18.227.254172.18.227.2551,022
186172.18.228.0/22172.18.228.1 to 172.18.231.254172.18.231.2551,022
187172.18.232.0/22172.18.232.1 to 172.18.235.254172.18.235.2551,022
188172.18.236.0/22172.18.236.1 to 172.18.239.254172.18.239.2551,022
189172.18.240.0/22172.18.240.1 to 172.18.243.254172.18.243.2551,022
190172.18.244.0/22172.18.244.1 to 172.18.247.254172.18.247.2551,022
191172.18.248.0/22172.18.248.1 to 172.18.251.254172.18.251.2551,022
192172.18.252.0/22172.18.252.1 to 172.18.255.254172.18.255.2551,022
193172.19.0.0/22172.19.0.1 to 172.19.3.254172.19.3.2551,022
194172.19.4.0/22172.19.4.1 to 172.19.7.254172.19.7.2551,022
195172.19.8.0/22172.19.8.1 to 172.19.11.254172.19.11.2551,022
196172.19.12.0/22172.19.12.1 to 172.19.15.254172.19.15.2551,022
197172.19.16.0/22172.19.16.1 to 172.19.19.254172.19.19.2551,022
198172.19.20.0/22172.19.20.1 to 172.19.23.254172.19.23.2551,022
199172.19.24.0/22172.19.24.1 to 172.19.27.254172.19.27.2551,022
200172.19.28.0/22172.19.28.1 to 172.19.31.254172.19.31.2551,022
201172.19.32.0/22172.19.32.1 to 172.19.35.254172.19.35.2551,022
202172.19.36.0/22172.19.36.1 to 172.19.39.254172.19.39.2551,022
203172.19.40.0/22172.19.40.1 to 172.19.43.254172.19.43.2551,022
204172.19.44.0/22172.19.44.1 to 172.19.47.254172.19.47.2551,022
205172.19.48.0/22172.19.48.1 to 172.19.51.254172.19.51.2551,022
206172.19.52.0/22172.19.52.1 to 172.19.55.254172.19.55.2551,022
207172.19.56.0/22172.19.56.1 to 172.19.59.254172.19.59.2551,022
208172.19.60.0/22172.19.60.1 to 172.19.63.254172.19.63.2551,022
209172.19.64.0/22172.19.64.1 to 172.19.67.254172.19.67.2551,022
210172.19.68.0/22172.19.68.1 to 172.19.71.254172.19.71.2551,022
211172.19.72.0/22172.19.72.1 to 172.19.75.254172.19.75.2551,022
212172.19.76.0/22172.19.76.1 to 172.19.79.254172.19.79.2551,022
213172.19.80.0/22172.19.80.1 to 172.19.83.254172.19.83.2551,022
214172.19.84.0/22172.19.84.1 to 172.19.87.254172.19.87.2551,022
215172.19.88.0/22172.19.88.1 to 172.19.91.254172.19.91.2551,022
216172.19.92.0/22172.19.92.1 to 172.19.95.254172.19.95.2551,022
217172.19.96.0/22172.19.96.1 to 172.19.99.254172.19.99.2551,022
218172.19.100.0/22172.19.100.1 to 172.19.103.254172.19.103.2551,022
219172.19.104.0/22172.19.104.1 to 172.19.107.254172.19.107.2551,022
220172.19.108.0/22172.19.108.1 to 172.19.111.254172.19.111.2551,022
221172.19.112.0/22172.19.112.1 to 172.19.115.254172.19.115.2551,022
222172.19.116.0/22172.19.116.1 to 172.19.119.254172.19.119.2551,022
223172.19.120.0/22172.19.120.1 to 172.19.123.254172.19.123.2551,022
224172.19.124.0/22172.19.124.1 to 172.19.127.254172.19.127.2551,022
225172.19.128.0/22172.19.128.1 to 172.19.131.254172.19.131.2551,022
226172.19.132.0/22172.19.132.1 to 172.19.135.254172.19.135.2551,022
227172.19.136.0/22172.19.136.1 to 172.19.139.254172.19.139.2551,022
228172.19.140.0/22172.19.140.1 to 172.19.143.254172.19.143.2551,022
229172.19.144.0/22172.19.144.1 to 172.19.147.254172.19.147.2551,022
230172.19.148.0/22172.19.148.1 to 172.19.151.254172.19.151.2551,022
231172.19.152.0/22172.19.152.1 to 172.19.155.254172.19.155.2551,022
232172.19.156.0/22172.19.156.1 to 172.19.159.254172.19.159.2551,022
233172.19.160.0/22172.19.160.1 to 172.19.163.254172.19.163.2551,022
234172.19.164.0/22172.19.164.1 to 172.19.167.254172.19.167.2551,022
235172.19.168.0/22172.19.168.1 to 172.19.171.254172.19.171.2551,022
236172.19.172.0/22172.19.172.1 to 172.19.175.254172.19.175.2551,022
237172.19.176.0/22172.19.176.1 to 172.19.179.254172.19.179.2551,022
238172.19.180.0/22172.19.180.1 to 172.19.183.254172.19.183.2551,022
239172.19.184.0/22172.19.184.1 to 172.19.187.254172.19.187.2551,022
240172.19.188.0/22172.19.188.1 to 172.19.191.254172.19.191.2551,022
241172.19.192.0/22172.19.192.1 to 172.19.195.254172.19.195.2551,022
242172.19.196.0/22172.19.196.1 to 172.19.199.254172.19.199.2551,022
243172.19.200.0/22172.19.200.1 to 172.19.203.254172.19.203.2551,022
244172.19.204.0/22172.19.204.1 to 172.19.207.254172.19.207.2551,022
245172.19.208.0/22172.19.208.1 to 172.19.211.254172.19.211.2551,022
246172.19.212.0/22172.19.212.1 to 172.19.215.254172.19.215.2551,022
247172.19.216.0/22172.19.216.1 to 172.19.219.254172.19.219.2551,022
248172.19.220.0/22172.19.220.1 to 172.19.223.254172.19.223.2551,022
249172.19.224.0/22172.19.224.1 to 172.19.227.254172.19.227.2551,022
250172.19.228.0/22172.19.228.1 to 172.19.231.254172.19.231.2551,022
251172.19.232.0/22172.19.232.1 to 172.19.235.254172.19.235.2551,022
252172.19.236.0/22172.19.236.1 to 172.19.239.254172.19.239.2551,022
253172.19.240.0/22172.19.240.1 to 172.19.243.254172.19.243.2551,022
254172.19.244.0/22172.19.244.1 to 172.19.247.254172.19.247.2551,022
255172.19.248.0/22172.19.248.1 to 172.19.251.254172.19.251.2551,022
256172.19.252.0/22172.19.252.1 to 172.19.255.254172.19.255.2551,022

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.