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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/24
/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 4,096 subnets of /24; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1172.16.0.0/24172.16.0.1 to 172.16.0.254172.16.0.255254
2172.16.1.0/24172.16.1.1 to 172.16.1.254172.16.1.255254
3172.16.2.0/24172.16.2.1 to 172.16.2.254172.16.2.255254
4172.16.3.0/24172.16.3.1 to 172.16.3.254172.16.3.255254
5172.16.4.0/24172.16.4.1 to 172.16.4.254172.16.4.255254
6172.16.5.0/24172.16.5.1 to 172.16.5.254172.16.5.255254
7172.16.6.0/24172.16.6.1 to 172.16.6.254172.16.6.255254
8172.16.7.0/24172.16.7.1 to 172.16.7.254172.16.7.255254
9172.16.8.0/24172.16.8.1 to 172.16.8.254172.16.8.255254
10172.16.9.0/24172.16.9.1 to 172.16.9.254172.16.9.255254
11172.16.10.0/24172.16.10.1 to 172.16.10.254172.16.10.255254
12172.16.11.0/24172.16.11.1 to 172.16.11.254172.16.11.255254
13172.16.12.0/24172.16.12.1 to 172.16.12.254172.16.12.255254
14172.16.13.0/24172.16.13.1 to 172.16.13.254172.16.13.255254
15172.16.14.0/24172.16.14.1 to 172.16.14.254172.16.14.255254
16172.16.15.0/24172.16.15.1 to 172.16.15.254172.16.15.255254
17172.16.16.0/24172.16.16.1 to 172.16.16.254172.16.16.255254
18172.16.17.0/24172.16.17.1 to 172.16.17.254172.16.17.255254
19172.16.18.0/24172.16.18.1 to 172.16.18.254172.16.18.255254
20172.16.19.0/24172.16.19.1 to 172.16.19.254172.16.19.255254
21172.16.20.0/24172.16.20.1 to 172.16.20.254172.16.20.255254
22172.16.21.0/24172.16.21.1 to 172.16.21.254172.16.21.255254
23172.16.22.0/24172.16.22.1 to 172.16.22.254172.16.22.255254
24172.16.23.0/24172.16.23.1 to 172.16.23.254172.16.23.255254
25172.16.24.0/24172.16.24.1 to 172.16.24.254172.16.24.255254
26172.16.25.0/24172.16.25.1 to 172.16.25.254172.16.25.255254
27172.16.26.0/24172.16.26.1 to 172.16.26.254172.16.26.255254
28172.16.27.0/24172.16.27.1 to 172.16.27.254172.16.27.255254
29172.16.28.0/24172.16.28.1 to 172.16.28.254172.16.28.255254
30172.16.29.0/24172.16.29.1 to 172.16.29.254172.16.29.255254
31172.16.30.0/24172.16.30.1 to 172.16.30.254172.16.30.255254
32172.16.31.0/24172.16.31.1 to 172.16.31.254172.16.31.255254
33172.16.32.0/24172.16.32.1 to 172.16.32.254172.16.32.255254
34172.16.33.0/24172.16.33.1 to 172.16.33.254172.16.33.255254
35172.16.34.0/24172.16.34.1 to 172.16.34.254172.16.34.255254
36172.16.35.0/24172.16.35.1 to 172.16.35.254172.16.35.255254
37172.16.36.0/24172.16.36.1 to 172.16.36.254172.16.36.255254
38172.16.37.0/24172.16.37.1 to 172.16.37.254172.16.37.255254
39172.16.38.0/24172.16.38.1 to 172.16.38.254172.16.38.255254
40172.16.39.0/24172.16.39.1 to 172.16.39.254172.16.39.255254
41172.16.40.0/24172.16.40.1 to 172.16.40.254172.16.40.255254
42172.16.41.0/24172.16.41.1 to 172.16.41.254172.16.41.255254
43172.16.42.0/24172.16.42.1 to 172.16.42.254172.16.42.255254
44172.16.43.0/24172.16.43.1 to 172.16.43.254172.16.43.255254
45172.16.44.0/24172.16.44.1 to 172.16.44.254172.16.44.255254
46172.16.45.0/24172.16.45.1 to 172.16.45.254172.16.45.255254
47172.16.46.0/24172.16.46.1 to 172.16.46.254172.16.46.255254
48172.16.47.0/24172.16.47.1 to 172.16.47.254172.16.47.255254
49172.16.48.0/24172.16.48.1 to 172.16.48.254172.16.48.255254
50172.16.49.0/24172.16.49.1 to 172.16.49.254172.16.49.255254
51172.16.50.0/24172.16.50.1 to 172.16.50.254172.16.50.255254
52172.16.51.0/24172.16.51.1 to 172.16.51.254172.16.51.255254
53172.16.52.0/24172.16.52.1 to 172.16.52.254172.16.52.255254
54172.16.53.0/24172.16.53.1 to 172.16.53.254172.16.53.255254
55172.16.54.0/24172.16.54.1 to 172.16.54.254172.16.54.255254
56172.16.55.0/24172.16.55.1 to 172.16.55.254172.16.55.255254
57172.16.56.0/24172.16.56.1 to 172.16.56.254172.16.56.255254
58172.16.57.0/24172.16.57.1 to 172.16.57.254172.16.57.255254
59172.16.58.0/24172.16.58.1 to 172.16.58.254172.16.58.255254
60172.16.59.0/24172.16.59.1 to 172.16.59.254172.16.59.255254
61172.16.60.0/24172.16.60.1 to 172.16.60.254172.16.60.255254
62172.16.61.0/24172.16.61.1 to 172.16.61.254172.16.61.255254
63172.16.62.0/24172.16.62.1 to 172.16.62.254172.16.62.255254
64172.16.63.0/24172.16.63.1 to 172.16.63.254172.16.63.255254
65172.16.64.0/24172.16.64.1 to 172.16.64.254172.16.64.255254
66172.16.65.0/24172.16.65.1 to 172.16.65.254172.16.65.255254
67172.16.66.0/24172.16.66.1 to 172.16.66.254172.16.66.255254
68172.16.67.0/24172.16.67.1 to 172.16.67.254172.16.67.255254
69172.16.68.0/24172.16.68.1 to 172.16.68.254172.16.68.255254
70172.16.69.0/24172.16.69.1 to 172.16.69.254172.16.69.255254
71172.16.70.0/24172.16.70.1 to 172.16.70.254172.16.70.255254
72172.16.71.0/24172.16.71.1 to 172.16.71.254172.16.71.255254
73172.16.72.0/24172.16.72.1 to 172.16.72.254172.16.72.255254
74172.16.73.0/24172.16.73.1 to 172.16.73.254172.16.73.255254
75172.16.74.0/24172.16.74.1 to 172.16.74.254172.16.74.255254
76172.16.75.0/24172.16.75.1 to 172.16.75.254172.16.75.255254
77172.16.76.0/24172.16.76.1 to 172.16.76.254172.16.76.255254
78172.16.77.0/24172.16.77.1 to 172.16.77.254172.16.77.255254
79172.16.78.0/24172.16.78.1 to 172.16.78.254172.16.78.255254
80172.16.79.0/24172.16.79.1 to 172.16.79.254172.16.79.255254
81172.16.80.0/24172.16.80.1 to 172.16.80.254172.16.80.255254
82172.16.81.0/24172.16.81.1 to 172.16.81.254172.16.81.255254
83172.16.82.0/24172.16.82.1 to 172.16.82.254172.16.82.255254
84172.16.83.0/24172.16.83.1 to 172.16.83.254172.16.83.255254
85172.16.84.0/24172.16.84.1 to 172.16.84.254172.16.84.255254
86172.16.85.0/24172.16.85.1 to 172.16.85.254172.16.85.255254
87172.16.86.0/24172.16.86.1 to 172.16.86.254172.16.86.255254
88172.16.87.0/24172.16.87.1 to 172.16.87.254172.16.87.255254
89172.16.88.0/24172.16.88.1 to 172.16.88.254172.16.88.255254
90172.16.89.0/24172.16.89.1 to 172.16.89.254172.16.89.255254
91172.16.90.0/24172.16.90.1 to 172.16.90.254172.16.90.255254
92172.16.91.0/24172.16.91.1 to 172.16.91.254172.16.91.255254
93172.16.92.0/24172.16.92.1 to 172.16.92.254172.16.92.255254
94172.16.93.0/24172.16.93.1 to 172.16.93.254172.16.93.255254
95172.16.94.0/24172.16.94.1 to 172.16.94.254172.16.94.255254
96172.16.95.0/24172.16.95.1 to 172.16.95.254172.16.95.255254
97172.16.96.0/24172.16.96.1 to 172.16.96.254172.16.96.255254
98172.16.97.0/24172.16.97.1 to 172.16.97.254172.16.97.255254
99172.16.98.0/24172.16.98.1 to 172.16.98.254172.16.98.255254
100172.16.99.0/24172.16.99.1 to 172.16.99.254172.16.99.255254
101172.16.100.0/24172.16.100.1 to 172.16.100.254172.16.100.255254
102172.16.101.0/24172.16.101.1 to 172.16.101.254172.16.101.255254
103172.16.102.0/24172.16.102.1 to 172.16.102.254172.16.102.255254
104172.16.103.0/24172.16.103.1 to 172.16.103.254172.16.103.255254
105172.16.104.0/24172.16.104.1 to 172.16.104.254172.16.104.255254
106172.16.105.0/24172.16.105.1 to 172.16.105.254172.16.105.255254
107172.16.106.0/24172.16.106.1 to 172.16.106.254172.16.106.255254
108172.16.107.0/24172.16.107.1 to 172.16.107.254172.16.107.255254
109172.16.108.0/24172.16.108.1 to 172.16.108.254172.16.108.255254
110172.16.109.0/24172.16.109.1 to 172.16.109.254172.16.109.255254
111172.16.110.0/24172.16.110.1 to 172.16.110.254172.16.110.255254
112172.16.111.0/24172.16.111.1 to 172.16.111.254172.16.111.255254
113172.16.112.0/24172.16.112.1 to 172.16.112.254172.16.112.255254
114172.16.113.0/24172.16.113.1 to 172.16.113.254172.16.113.255254
115172.16.114.0/24172.16.114.1 to 172.16.114.254172.16.114.255254
116172.16.115.0/24172.16.115.1 to 172.16.115.254172.16.115.255254
117172.16.116.0/24172.16.116.1 to 172.16.116.254172.16.116.255254
118172.16.117.0/24172.16.117.1 to 172.16.117.254172.16.117.255254
119172.16.118.0/24172.16.118.1 to 172.16.118.254172.16.118.255254
120172.16.119.0/24172.16.119.1 to 172.16.119.254172.16.119.255254
121172.16.120.0/24172.16.120.1 to 172.16.120.254172.16.120.255254
122172.16.121.0/24172.16.121.1 to 172.16.121.254172.16.121.255254
123172.16.122.0/24172.16.122.1 to 172.16.122.254172.16.122.255254
124172.16.123.0/24172.16.123.1 to 172.16.123.254172.16.123.255254
125172.16.124.0/24172.16.124.1 to 172.16.124.254172.16.124.255254
126172.16.125.0/24172.16.125.1 to 172.16.125.254172.16.125.255254
127172.16.126.0/24172.16.126.1 to 172.16.126.254172.16.126.255254
128172.16.127.0/24172.16.127.1 to 172.16.127.254172.16.127.255254
129172.16.128.0/24172.16.128.1 to 172.16.128.254172.16.128.255254
130172.16.129.0/24172.16.129.1 to 172.16.129.254172.16.129.255254
131172.16.130.0/24172.16.130.1 to 172.16.130.254172.16.130.255254
132172.16.131.0/24172.16.131.1 to 172.16.131.254172.16.131.255254
133172.16.132.0/24172.16.132.1 to 172.16.132.254172.16.132.255254
134172.16.133.0/24172.16.133.1 to 172.16.133.254172.16.133.255254
135172.16.134.0/24172.16.134.1 to 172.16.134.254172.16.134.255254
136172.16.135.0/24172.16.135.1 to 172.16.135.254172.16.135.255254
137172.16.136.0/24172.16.136.1 to 172.16.136.254172.16.136.255254
138172.16.137.0/24172.16.137.1 to 172.16.137.254172.16.137.255254
139172.16.138.0/24172.16.138.1 to 172.16.138.254172.16.138.255254
140172.16.139.0/24172.16.139.1 to 172.16.139.254172.16.139.255254
141172.16.140.0/24172.16.140.1 to 172.16.140.254172.16.140.255254
142172.16.141.0/24172.16.141.1 to 172.16.141.254172.16.141.255254
143172.16.142.0/24172.16.142.1 to 172.16.142.254172.16.142.255254
144172.16.143.0/24172.16.143.1 to 172.16.143.254172.16.143.255254
145172.16.144.0/24172.16.144.1 to 172.16.144.254172.16.144.255254
146172.16.145.0/24172.16.145.1 to 172.16.145.254172.16.145.255254
147172.16.146.0/24172.16.146.1 to 172.16.146.254172.16.146.255254
148172.16.147.0/24172.16.147.1 to 172.16.147.254172.16.147.255254
149172.16.148.0/24172.16.148.1 to 172.16.148.254172.16.148.255254
150172.16.149.0/24172.16.149.1 to 172.16.149.254172.16.149.255254
151172.16.150.0/24172.16.150.1 to 172.16.150.254172.16.150.255254
152172.16.151.0/24172.16.151.1 to 172.16.151.254172.16.151.255254
153172.16.152.0/24172.16.152.1 to 172.16.152.254172.16.152.255254
154172.16.153.0/24172.16.153.1 to 172.16.153.254172.16.153.255254
155172.16.154.0/24172.16.154.1 to 172.16.154.254172.16.154.255254
156172.16.155.0/24172.16.155.1 to 172.16.155.254172.16.155.255254
157172.16.156.0/24172.16.156.1 to 172.16.156.254172.16.156.255254
158172.16.157.0/24172.16.157.1 to 172.16.157.254172.16.157.255254
159172.16.158.0/24172.16.158.1 to 172.16.158.254172.16.158.255254
160172.16.159.0/24172.16.159.1 to 172.16.159.254172.16.159.255254
161172.16.160.0/24172.16.160.1 to 172.16.160.254172.16.160.255254
162172.16.161.0/24172.16.161.1 to 172.16.161.254172.16.161.255254
163172.16.162.0/24172.16.162.1 to 172.16.162.254172.16.162.255254
164172.16.163.0/24172.16.163.1 to 172.16.163.254172.16.163.255254
165172.16.164.0/24172.16.164.1 to 172.16.164.254172.16.164.255254
166172.16.165.0/24172.16.165.1 to 172.16.165.254172.16.165.255254
167172.16.166.0/24172.16.166.1 to 172.16.166.254172.16.166.255254
168172.16.167.0/24172.16.167.1 to 172.16.167.254172.16.167.255254
169172.16.168.0/24172.16.168.1 to 172.16.168.254172.16.168.255254
170172.16.169.0/24172.16.169.1 to 172.16.169.254172.16.169.255254
171172.16.170.0/24172.16.170.1 to 172.16.170.254172.16.170.255254
172172.16.171.0/24172.16.171.1 to 172.16.171.254172.16.171.255254
173172.16.172.0/24172.16.172.1 to 172.16.172.254172.16.172.255254
174172.16.173.0/24172.16.173.1 to 172.16.173.254172.16.173.255254
175172.16.174.0/24172.16.174.1 to 172.16.174.254172.16.174.255254
176172.16.175.0/24172.16.175.1 to 172.16.175.254172.16.175.255254
177172.16.176.0/24172.16.176.1 to 172.16.176.254172.16.176.255254
178172.16.177.0/24172.16.177.1 to 172.16.177.254172.16.177.255254
179172.16.178.0/24172.16.178.1 to 172.16.178.254172.16.178.255254
180172.16.179.0/24172.16.179.1 to 172.16.179.254172.16.179.255254
181172.16.180.0/24172.16.180.1 to 172.16.180.254172.16.180.255254
182172.16.181.0/24172.16.181.1 to 172.16.181.254172.16.181.255254
183172.16.182.0/24172.16.182.1 to 172.16.182.254172.16.182.255254
184172.16.183.0/24172.16.183.1 to 172.16.183.254172.16.183.255254
185172.16.184.0/24172.16.184.1 to 172.16.184.254172.16.184.255254
186172.16.185.0/24172.16.185.1 to 172.16.185.254172.16.185.255254
187172.16.186.0/24172.16.186.1 to 172.16.186.254172.16.186.255254
188172.16.187.0/24172.16.187.1 to 172.16.187.254172.16.187.255254
189172.16.188.0/24172.16.188.1 to 172.16.188.254172.16.188.255254
190172.16.189.0/24172.16.189.1 to 172.16.189.254172.16.189.255254
191172.16.190.0/24172.16.190.1 to 172.16.190.254172.16.190.255254
192172.16.191.0/24172.16.191.1 to 172.16.191.254172.16.191.255254
193172.16.192.0/24172.16.192.1 to 172.16.192.254172.16.192.255254
194172.16.193.0/24172.16.193.1 to 172.16.193.254172.16.193.255254
195172.16.194.0/24172.16.194.1 to 172.16.194.254172.16.194.255254
196172.16.195.0/24172.16.195.1 to 172.16.195.254172.16.195.255254
197172.16.196.0/24172.16.196.1 to 172.16.196.254172.16.196.255254
198172.16.197.0/24172.16.197.1 to 172.16.197.254172.16.197.255254
199172.16.198.0/24172.16.198.1 to 172.16.198.254172.16.198.255254
200172.16.199.0/24172.16.199.1 to 172.16.199.254172.16.199.255254
201172.16.200.0/24172.16.200.1 to 172.16.200.254172.16.200.255254
202172.16.201.0/24172.16.201.1 to 172.16.201.254172.16.201.255254
203172.16.202.0/24172.16.202.1 to 172.16.202.254172.16.202.255254
204172.16.203.0/24172.16.203.1 to 172.16.203.254172.16.203.255254
205172.16.204.0/24172.16.204.1 to 172.16.204.254172.16.204.255254
206172.16.205.0/24172.16.205.1 to 172.16.205.254172.16.205.255254
207172.16.206.0/24172.16.206.1 to 172.16.206.254172.16.206.255254
208172.16.207.0/24172.16.207.1 to 172.16.207.254172.16.207.255254
209172.16.208.0/24172.16.208.1 to 172.16.208.254172.16.208.255254
210172.16.209.0/24172.16.209.1 to 172.16.209.254172.16.209.255254
211172.16.210.0/24172.16.210.1 to 172.16.210.254172.16.210.255254
212172.16.211.0/24172.16.211.1 to 172.16.211.254172.16.211.255254
213172.16.212.0/24172.16.212.1 to 172.16.212.254172.16.212.255254
214172.16.213.0/24172.16.213.1 to 172.16.213.254172.16.213.255254
215172.16.214.0/24172.16.214.1 to 172.16.214.254172.16.214.255254
216172.16.215.0/24172.16.215.1 to 172.16.215.254172.16.215.255254
217172.16.216.0/24172.16.216.1 to 172.16.216.254172.16.216.255254
218172.16.217.0/24172.16.217.1 to 172.16.217.254172.16.217.255254
219172.16.218.0/24172.16.218.1 to 172.16.218.254172.16.218.255254
220172.16.219.0/24172.16.219.1 to 172.16.219.254172.16.219.255254
221172.16.220.0/24172.16.220.1 to 172.16.220.254172.16.220.255254
222172.16.221.0/24172.16.221.1 to 172.16.221.254172.16.221.255254
223172.16.222.0/24172.16.222.1 to 172.16.222.254172.16.222.255254
224172.16.223.0/24172.16.223.1 to 172.16.223.254172.16.223.255254
225172.16.224.0/24172.16.224.1 to 172.16.224.254172.16.224.255254
226172.16.225.0/24172.16.225.1 to 172.16.225.254172.16.225.255254
227172.16.226.0/24172.16.226.1 to 172.16.226.254172.16.226.255254
228172.16.227.0/24172.16.227.1 to 172.16.227.254172.16.227.255254
229172.16.228.0/24172.16.228.1 to 172.16.228.254172.16.228.255254
230172.16.229.0/24172.16.229.1 to 172.16.229.254172.16.229.255254
231172.16.230.0/24172.16.230.1 to 172.16.230.254172.16.230.255254
232172.16.231.0/24172.16.231.1 to 172.16.231.254172.16.231.255254
233172.16.232.0/24172.16.232.1 to 172.16.232.254172.16.232.255254
234172.16.233.0/24172.16.233.1 to 172.16.233.254172.16.233.255254
235172.16.234.0/24172.16.234.1 to 172.16.234.254172.16.234.255254
236172.16.235.0/24172.16.235.1 to 172.16.235.254172.16.235.255254
237172.16.236.0/24172.16.236.1 to 172.16.236.254172.16.236.255254
238172.16.237.0/24172.16.237.1 to 172.16.237.254172.16.237.255254
239172.16.238.0/24172.16.238.1 to 172.16.238.254172.16.238.255254
240172.16.239.0/24172.16.239.1 to 172.16.239.254172.16.239.255254
241172.16.240.0/24172.16.240.1 to 172.16.240.254172.16.240.255254
242172.16.241.0/24172.16.241.1 to 172.16.241.254172.16.241.255254
243172.16.242.0/24172.16.242.1 to 172.16.242.254172.16.242.255254
244172.16.243.0/24172.16.243.1 to 172.16.243.254172.16.243.255254
245172.16.244.0/24172.16.244.1 to 172.16.244.254172.16.244.255254
246172.16.245.0/24172.16.245.1 to 172.16.245.254172.16.245.255254
247172.16.246.0/24172.16.246.1 to 172.16.246.254172.16.246.255254
248172.16.247.0/24172.16.247.1 to 172.16.247.254172.16.247.255254
249172.16.248.0/24172.16.248.1 to 172.16.248.254172.16.248.255254
250172.16.249.0/24172.16.249.1 to 172.16.249.254172.16.249.255254
251172.16.250.0/24172.16.250.1 to 172.16.250.254172.16.250.255254
252172.16.251.0/24172.16.251.1 to 172.16.251.254172.16.251.255254
253172.16.252.0/24172.16.252.1 to 172.16.252.254172.16.252.255254
254172.16.253.0/24172.16.253.1 to 172.16.253.254172.16.253.255254
255172.16.254.0/24172.16.254.1 to 172.16.254.254172.16.254.255254
256172.16.255.0/24172.16.255.1 to 172.16.255.254172.16.255.255254

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.