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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.

Network233.80.0.0/12
Usable hosts1,048,574
Subnet mask255.240.0.0
Addresses1,048,576
Network address
233.80.0.0
Broadcast address
233.95.255.255
First usable
233.80.0.1
Last usable
233.95.255.254
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
Multicast 224.0.0.0/4
One-to-many traffic, such as IPTV and routing protocols
Old class
D (multicast)
As numbers
Hex E9500000 · Integer 3914334208 to 3915382783
Reverse DNS zones
80.233.in-addr.arpa
81.233.in-addr.arpa
82.233.in-addr.arpa
83.233.in-addr.arpa
84.233.in-addr.arpa
85.233.in-addr.arpa
86.233.in-addr.arpa
87.233.in-addr.arpa
88.233.in-addr.arpa
89.233.in-addr.arpa
90.233.in-addr.arpa
91.233.in-addr.arpa
92.233.in-addr.arpa
93.233.in-addr.arpa
94.233.in-addr.arpa
95.233.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
Address11101001.01010000.00000000.00000000233.80.0.0
Subnet mask11111111.11110000.00000000.00000000255.240.0.0
Network11101001.01010000.00000000.00000000233.80.0.0
Broadcast11101001.01011111.11111111.11111111233.95.255.255
Split into smaller subnets/21
/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)

233.80.0.0/12 makes 512 subnets of /21; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1233.80.0.0/21233.80.0.1 to 233.80.7.254233.80.7.2552,046
2233.80.8.0/21233.80.8.1 to 233.80.15.254233.80.15.2552,046
3233.80.16.0/21233.80.16.1 to 233.80.23.254233.80.23.2552,046
4233.80.24.0/21233.80.24.1 to 233.80.31.254233.80.31.2552,046
5233.80.32.0/21233.80.32.1 to 233.80.39.254233.80.39.2552,046
6233.80.40.0/21233.80.40.1 to 233.80.47.254233.80.47.2552,046
7233.80.48.0/21233.80.48.1 to 233.80.55.254233.80.55.2552,046
8233.80.56.0/21233.80.56.1 to 233.80.63.254233.80.63.2552,046
9233.80.64.0/21233.80.64.1 to 233.80.71.254233.80.71.2552,046
10233.80.72.0/21233.80.72.1 to 233.80.79.254233.80.79.2552,046
11233.80.80.0/21233.80.80.1 to 233.80.87.254233.80.87.2552,046
12233.80.88.0/21233.80.88.1 to 233.80.95.254233.80.95.2552,046
13233.80.96.0/21233.80.96.1 to 233.80.103.254233.80.103.2552,046
14233.80.104.0/21233.80.104.1 to 233.80.111.254233.80.111.2552,046
15233.80.112.0/21233.80.112.1 to 233.80.119.254233.80.119.2552,046
16233.80.120.0/21233.80.120.1 to 233.80.127.254233.80.127.2552,046
17233.80.128.0/21233.80.128.1 to 233.80.135.254233.80.135.2552,046
18233.80.136.0/21233.80.136.1 to 233.80.143.254233.80.143.2552,046
19233.80.144.0/21233.80.144.1 to 233.80.151.254233.80.151.2552,046
20233.80.152.0/21233.80.152.1 to 233.80.159.254233.80.159.2552,046
21233.80.160.0/21233.80.160.1 to 233.80.167.254233.80.167.2552,046
22233.80.168.0/21233.80.168.1 to 233.80.175.254233.80.175.2552,046
23233.80.176.0/21233.80.176.1 to 233.80.183.254233.80.183.2552,046
24233.80.184.0/21233.80.184.1 to 233.80.191.254233.80.191.2552,046
25233.80.192.0/21233.80.192.1 to 233.80.199.254233.80.199.2552,046
26233.80.200.0/21233.80.200.1 to 233.80.207.254233.80.207.2552,046
27233.80.208.0/21233.80.208.1 to 233.80.215.254233.80.215.2552,046
28233.80.216.0/21233.80.216.1 to 233.80.223.254233.80.223.2552,046
29233.80.224.0/21233.80.224.1 to 233.80.231.254233.80.231.2552,046
30233.80.232.0/21233.80.232.1 to 233.80.239.254233.80.239.2552,046
31233.80.240.0/21233.80.240.1 to 233.80.247.254233.80.247.2552,046
32233.80.248.0/21233.80.248.1 to 233.80.255.254233.80.255.2552,046
33233.81.0.0/21233.81.0.1 to 233.81.7.254233.81.7.2552,046
34233.81.8.0/21233.81.8.1 to 233.81.15.254233.81.15.2552,046
35233.81.16.0/21233.81.16.1 to 233.81.23.254233.81.23.2552,046
36233.81.24.0/21233.81.24.1 to 233.81.31.254233.81.31.2552,046
37233.81.32.0/21233.81.32.1 to 233.81.39.254233.81.39.2552,046
38233.81.40.0/21233.81.40.1 to 233.81.47.254233.81.47.2552,046
39233.81.48.0/21233.81.48.1 to 233.81.55.254233.81.55.2552,046
40233.81.56.0/21233.81.56.1 to 233.81.63.254233.81.63.2552,046
41233.81.64.0/21233.81.64.1 to 233.81.71.254233.81.71.2552,046
42233.81.72.0/21233.81.72.1 to 233.81.79.254233.81.79.2552,046
43233.81.80.0/21233.81.80.1 to 233.81.87.254233.81.87.2552,046
44233.81.88.0/21233.81.88.1 to 233.81.95.254233.81.95.2552,046
45233.81.96.0/21233.81.96.1 to 233.81.103.254233.81.103.2552,046
46233.81.104.0/21233.81.104.1 to 233.81.111.254233.81.111.2552,046
47233.81.112.0/21233.81.112.1 to 233.81.119.254233.81.119.2552,046
48233.81.120.0/21233.81.120.1 to 233.81.127.254233.81.127.2552,046
49233.81.128.0/21233.81.128.1 to 233.81.135.254233.81.135.2552,046
50233.81.136.0/21233.81.136.1 to 233.81.143.254233.81.143.2552,046
51233.81.144.0/21233.81.144.1 to 233.81.151.254233.81.151.2552,046
52233.81.152.0/21233.81.152.1 to 233.81.159.254233.81.159.2552,046
53233.81.160.0/21233.81.160.1 to 233.81.167.254233.81.167.2552,046
54233.81.168.0/21233.81.168.1 to 233.81.175.254233.81.175.2552,046
55233.81.176.0/21233.81.176.1 to 233.81.183.254233.81.183.2552,046
56233.81.184.0/21233.81.184.1 to 233.81.191.254233.81.191.2552,046
57233.81.192.0/21233.81.192.1 to 233.81.199.254233.81.199.2552,046
58233.81.200.0/21233.81.200.1 to 233.81.207.254233.81.207.2552,046
59233.81.208.0/21233.81.208.1 to 233.81.215.254233.81.215.2552,046
60233.81.216.0/21233.81.216.1 to 233.81.223.254233.81.223.2552,046
61233.81.224.0/21233.81.224.1 to 233.81.231.254233.81.231.2552,046
62233.81.232.0/21233.81.232.1 to 233.81.239.254233.81.239.2552,046
63233.81.240.0/21233.81.240.1 to 233.81.247.254233.81.247.2552,046
64233.81.248.0/21233.81.248.1 to 233.81.255.254233.81.255.2552,046
65233.82.0.0/21233.82.0.1 to 233.82.7.254233.82.7.2552,046
66233.82.8.0/21233.82.8.1 to 233.82.15.254233.82.15.2552,046
67233.82.16.0/21233.82.16.1 to 233.82.23.254233.82.23.2552,046
68233.82.24.0/21233.82.24.1 to 233.82.31.254233.82.31.2552,046
69233.82.32.0/21233.82.32.1 to 233.82.39.254233.82.39.2552,046
70233.82.40.0/21233.82.40.1 to 233.82.47.254233.82.47.2552,046
71233.82.48.0/21233.82.48.1 to 233.82.55.254233.82.55.2552,046
72233.82.56.0/21233.82.56.1 to 233.82.63.254233.82.63.2552,046
73233.82.64.0/21233.82.64.1 to 233.82.71.254233.82.71.2552,046
74233.82.72.0/21233.82.72.1 to 233.82.79.254233.82.79.2552,046
75233.82.80.0/21233.82.80.1 to 233.82.87.254233.82.87.2552,046
76233.82.88.0/21233.82.88.1 to 233.82.95.254233.82.95.2552,046
77233.82.96.0/21233.82.96.1 to 233.82.103.254233.82.103.2552,046
78233.82.104.0/21233.82.104.1 to 233.82.111.254233.82.111.2552,046
79233.82.112.0/21233.82.112.1 to 233.82.119.254233.82.119.2552,046
80233.82.120.0/21233.82.120.1 to 233.82.127.254233.82.127.2552,046
81233.82.128.0/21233.82.128.1 to 233.82.135.254233.82.135.2552,046
82233.82.136.0/21233.82.136.1 to 233.82.143.254233.82.143.2552,046
83233.82.144.0/21233.82.144.1 to 233.82.151.254233.82.151.2552,046
84233.82.152.0/21233.82.152.1 to 233.82.159.254233.82.159.2552,046
85233.82.160.0/21233.82.160.1 to 233.82.167.254233.82.167.2552,046
86233.82.168.0/21233.82.168.1 to 233.82.175.254233.82.175.2552,046
87233.82.176.0/21233.82.176.1 to 233.82.183.254233.82.183.2552,046
88233.82.184.0/21233.82.184.1 to 233.82.191.254233.82.191.2552,046
89233.82.192.0/21233.82.192.1 to 233.82.199.254233.82.199.2552,046
90233.82.200.0/21233.82.200.1 to 233.82.207.254233.82.207.2552,046
91233.82.208.0/21233.82.208.1 to 233.82.215.254233.82.215.2552,046
92233.82.216.0/21233.82.216.1 to 233.82.223.254233.82.223.2552,046
93233.82.224.0/21233.82.224.1 to 233.82.231.254233.82.231.2552,046
94233.82.232.0/21233.82.232.1 to 233.82.239.254233.82.239.2552,046
95233.82.240.0/21233.82.240.1 to 233.82.247.254233.82.247.2552,046
96233.82.248.0/21233.82.248.1 to 233.82.255.254233.82.255.2552,046
97233.83.0.0/21233.83.0.1 to 233.83.7.254233.83.7.2552,046
98233.83.8.0/21233.83.8.1 to 233.83.15.254233.83.15.2552,046
99233.83.16.0/21233.83.16.1 to 233.83.23.254233.83.23.2552,046
100233.83.24.0/21233.83.24.1 to 233.83.31.254233.83.31.2552,046
101233.83.32.0/21233.83.32.1 to 233.83.39.254233.83.39.2552,046
102233.83.40.0/21233.83.40.1 to 233.83.47.254233.83.47.2552,046
103233.83.48.0/21233.83.48.1 to 233.83.55.254233.83.55.2552,046
104233.83.56.0/21233.83.56.1 to 233.83.63.254233.83.63.2552,046
105233.83.64.0/21233.83.64.1 to 233.83.71.254233.83.71.2552,046
106233.83.72.0/21233.83.72.1 to 233.83.79.254233.83.79.2552,046
107233.83.80.0/21233.83.80.1 to 233.83.87.254233.83.87.2552,046
108233.83.88.0/21233.83.88.1 to 233.83.95.254233.83.95.2552,046
109233.83.96.0/21233.83.96.1 to 233.83.103.254233.83.103.2552,046
110233.83.104.0/21233.83.104.1 to 233.83.111.254233.83.111.2552,046
111233.83.112.0/21233.83.112.1 to 233.83.119.254233.83.119.2552,046
112233.83.120.0/21233.83.120.1 to 233.83.127.254233.83.127.2552,046
113233.83.128.0/21233.83.128.1 to 233.83.135.254233.83.135.2552,046
114233.83.136.0/21233.83.136.1 to 233.83.143.254233.83.143.2552,046
115233.83.144.0/21233.83.144.1 to 233.83.151.254233.83.151.2552,046
116233.83.152.0/21233.83.152.1 to 233.83.159.254233.83.159.2552,046
117233.83.160.0/21233.83.160.1 to 233.83.167.254233.83.167.2552,046
118233.83.168.0/21233.83.168.1 to 233.83.175.254233.83.175.2552,046
119233.83.176.0/21233.83.176.1 to 233.83.183.254233.83.183.2552,046
120233.83.184.0/21233.83.184.1 to 233.83.191.254233.83.191.2552,046
121233.83.192.0/21233.83.192.1 to 233.83.199.254233.83.199.2552,046
122233.83.200.0/21233.83.200.1 to 233.83.207.254233.83.207.2552,046
123233.83.208.0/21233.83.208.1 to 233.83.215.254233.83.215.2552,046
124233.83.216.0/21233.83.216.1 to 233.83.223.254233.83.223.2552,046
125233.83.224.0/21233.83.224.1 to 233.83.231.254233.83.231.2552,046
126233.83.232.0/21233.83.232.1 to 233.83.239.254233.83.239.2552,046
127233.83.240.0/21233.83.240.1 to 233.83.247.254233.83.247.2552,046
128233.83.248.0/21233.83.248.1 to 233.83.255.254233.83.255.2552,046
129233.84.0.0/21233.84.0.1 to 233.84.7.254233.84.7.2552,046
130233.84.8.0/21233.84.8.1 to 233.84.15.254233.84.15.2552,046
131233.84.16.0/21233.84.16.1 to 233.84.23.254233.84.23.2552,046
132233.84.24.0/21233.84.24.1 to 233.84.31.254233.84.31.2552,046
133233.84.32.0/21233.84.32.1 to 233.84.39.254233.84.39.2552,046
134233.84.40.0/21233.84.40.1 to 233.84.47.254233.84.47.2552,046
135233.84.48.0/21233.84.48.1 to 233.84.55.254233.84.55.2552,046
136233.84.56.0/21233.84.56.1 to 233.84.63.254233.84.63.2552,046
137233.84.64.0/21233.84.64.1 to 233.84.71.254233.84.71.2552,046
138233.84.72.0/21233.84.72.1 to 233.84.79.254233.84.79.2552,046
139233.84.80.0/21233.84.80.1 to 233.84.87.254233.84.87.2552,046
140233.84.88.0/21233.84.88.1 to 233.84.95.254233.84.95.2552,046
141233.84.96.0/21233.84.96.1 to 233.84.103.254233.84.103.2552,046
142233.84.104.0/21233.84.104.1 to 233.84.111.254233.84.111.2552,046
143233.84.112.0/21233.84.112.1 to 233.84.119.254233.84.119.2552,046
144233.84.120.0/21233.84.120.1 to 233.84.127.254233.84.127.2552,046
145233.84.128.0/21233.84.128.1 to 233.84.135.254233.84.135.2552,046
146233.84.136.0/21233.84.136.1 to 233.84.143.254233.84.143.2552,046
147233.84.144.0/21233.84.144.1 to 233.84.151.254233.84.151.2552,046
148233.84.152.0/21233.84.152.1 to 233.84.159.254233.84.159.2552,046
149233.84.160.0/21233.84.160.1 to 233.84.167.254233.84.167.2552,046
150233.84.168.0/21233.84.168.1 to 233.84.175.254233.84.175.2552,046
151233.84.176.0/21233.84.176.1 to 233.84.183.254233.84.183.2552,046
152233.84.184.0/21233.84.184.1 to 233.84.191.254233.84.191.2552,046
153233.84.192.0/21233.84.192.1 to 233.84.199.254233.84.199.2552,046
154233.84.200.0/21233.84.200.1 to 233.84.207.254233.84.207.2552,046
155233.84.208.0/21233.84.208.1 to 233.84.215.254233.84.215.2552,046
156233.84.216.0/21233.84.216.1 to 233.84.223.254233.84.223.2552,046
157233.84.224.0/21233.84.224.1 to 233.84.231.254233.84.231.2552,046
158233.84.232.0/21233.84.232.1 to 233.84.239.254233.84.239.2552,046
159233.84.240.0/21233.84.240.1 to 233.84.247.254233.84.247.2552,046
160233.84.248.0/21233.84.248.1 to 233.84.255.254233.84.255.2552,046
161233.85.0.0/21233.85.0.1 to 233.85.7.254233.85.7.2552,046
162233.85.8.0/21233.85.8.1 to 233.85.15.254233.85.15.2552,046
163233.85.16.0/21233.85.16.1 to 233.85.23.254233.85.23.2552,046
164233.85.24.0/21233.85.24.1 to 233.85.31.254233.85.31.2552,046
165233.85.32.0/21233.85.32.1 to 233.85.39.254233.85.39.2552,046
166233.85.40.0/21233.85.40.1 to 233.85.47.254233.85.47.2552,046
167233.85.48.0/21233.85.48.1 to 233.85.55.254233.85.55.2552,046
168233.85.56.0/21233.85.56.1 to 233.85.63.254233.85.63.2552,046
169233.85.64.0/21233.85.64.1 to 233.85.71.254233.85.71.2552,046
170233.85.72.0/21233.85.72.1 to 233.85.79.254233.85.79.2552,046
171233.85.80.0/21233.85.80.1 to 233.85.87.254233.85.87.2552,046
172233.85.88.0/21233.85.88.1 to 233.85.95.254233.85.95.2552,046
173233.85.96.0/21233.85.96.1 to 233.85.103.254233.85.103.2552,046
174233.85.104.0/21233.85.104.1 to 233.85.111.254233.85.111.2552,046
175233.85.112.0/21233.85.112.1 to 233.85.119.254233.85.119.2552,046
176233.85.120.0/21233.85.120.1 to 233.85.127.254233.85.127.2552,046
177233.85.128.0/21233.85.128.1 to 233.85.135.254233.85.135.2552,046
178233.85.136.0/21233.85.136.1 to 233.85.143.254233.85.143.2552,046
179233.85.144.0/21233.85.144.1 to 233.85.151.254233.85.151.2552,046
180233.85.152.0/21233.85.152.1 to 233.85.159.254233.85.159.2552,046
181233.85.160.0/21233.85.160.1 to 233.85.167.254233.85.167.2552,046
182233.85.168.0/21233.85.168.1 to 233.85.175.254233.85.175.2552,046
183233.85.176.0/21233.85.176.1 to 233.85.183.254233.85.183.2552,046
184233.85.184.0/21233.85.184.1 to 233.85.191.254233.85.191.2552,046
185233.85.192.0/21233.85.192.1 to 233.85.199.254233.85.199.2552,046
186233.85.200.0/21233.85.200.1 to 233.85.207.254233.85.207.2552,046
187233.85.208.0/21233.85.208.1 to 233.85.215.254233.85.215.2552,046
188233.85.216.0/21233.85.216.1 to 233.85.223.254233.85.223.2552,046
189233.85.224.0/21233.85.224.1 to 233.85.231.254233.85.231.2552,046
190233.85.232.0/21233.85.232.1 to 233.85.239.254233.85.239.2552,046
191233.85.240.0/21233.85.240.1 to 233.85.247.254233.85.247.2552,046
192233.85.248.0/21233.85.248.1 to 233.85.255.254233.85.255.2552,046
193233.86.0.0/21233.86.0.1 to 233.86.7.254233.86.7.2552,046
194233.86.8.0/21233.86.8.1 to 233.86.15.254233.86.15.2552,046
195233.86.16.0/21233.86.16.1 to 233.86.23.254233.86.23.2552,046
196233.86.24.0/21233.86.24.1 to 233.86.31.254233.86.31.2552,046
197233.86.32.0/21233.86.32.1 to 233.86.39.254233.86.39.2552,046
198233.86.40.0/21233.86.40.1 to 233.86.47.254233.86.47.2552,046
199233.86.48.0/21233.86.48.1 to 233.86.55.254233.86.55.2552,046
200233.86.56.0/21233.86.56.1 to 233.86.63.254233.86.63.2552,046
201233.86.64.0/21233.86.64.1 to 233.86.71.254233.86.71.2552,046
202233.86.72.0/21233.86.72.1 to 233.86.79.254233.86.79.2552,046
203233.86.80.0/21233.86.80.1 to 233.86.87.254233.86.87.2552,046
204233.86.88.0/21233.86.88.1 to 233.86.95.254233.86.95.2552,046
205233.86.96.0/21233.86.96.1 to 233.86.103.254233.86.103.2552,046
206233.86.104.0/21233.86.104.1 to 233.86.111.254233.86.111.2552,046
207233.86.112.0/21233.86.112.1 to 233.86.119.254233.86.119.2552,046
208233.86.120.0/21233.86.120.1 to 233.86.127.254233.86.127.2552,046
209233.86.128.0/21233.86.128.1 to 233.86.135.254233.86.135.2552,046
210233.86.136.0/21233.86.136.1 to 233.86.143.254233.86.143.2552,046
211233.86.144.0/21233.86.144.1 to 233.86.151.254233.86.151.2552,046
212233.86.152.0/21233.86.152.1 to 233.86.159.254233.86.159.2552,046
213233.86.160.0/21233.86.160.1 to 233.86.167.254233.86.167.2552,046
214233.86.168.0/21233.86.168.1 to 233.86.175.254233.86.175.2552,046
215233.86.176.0/21233.86.176.1 to 233.86.183.254233.86.183.2552,046
216233.86.184.0/21233.86.184.1 to 233.86.191.254233.86.191.2552,046
217233.86.192.0/21233.86.192.1 to 233.86.199.254233.86.199.2552,046
218233.86.200.0/21233.86.200.1 to 233.86.207.254233.86.207.2552,046
219233.86.208.0/21233.86.208.1 to 233.86.215.254233.86.215.2552,046
220233.86.216.0/21233.86.216.1 to 233.86.223.254233.86.223.2552,046
221233.86.224.0/21233.86.224.1 to 233.86.231.254233.86.231.2552,046
222233.86.232.0/21233.86.232.1 to 233.86.239.254233.86.239.2552,046
223233.86.240.0/21233.86.240.1 to 233.86.247.254233.86.247.2552,046
224233.86.248.0/21233.86.248.1 to 233.86.255.254233.86.255.2552,046
225233.87.0.0/21233.87.0.1 to 233.87.7.254233.87.7.2552,046
226233.87.8.0/21233.87.8.1 to 233.87.15.254233.87.15.2552,046
227233.87.16.0/21233.87.16.1 to 233.87.23.254233.87.23.2552,046
228233.87.24.0/21233.87.24.1 to 233.87.31.254233.87.31.2552,046
229233.87.32.0/21233.87.32.1 to 233.87.39.254233.87.39.2552,046
230233.87.40.0/21233.87.40.1 to 233.87.47.254233.87.47.2552,046
231233.87.48.0/21233.87.48.1 to 233.87.55.254233.87.55.2552,046
232233.87.56.0/21233.87.56.1 to 233.87.63.254233.87.63.2552,046
233233.87.64.0/21233.87.64.1 to 233.87.71.254233.87.71.2552,046
234233.87.72.0/21233.87.72.1 to 233.87.79.254233.87.79.2552,046
235233.87.80.0/21233.87.80.1 to 233.87.87.254233.87.87.2552,046
236233.87.88.0/21233.87.88.1 to 233.87.95.254233.87.95.2552,046
237233.87.96.0/21233.87.96.1 to 233.87.103.254233.87.103.2552,046
238233.87.104.0/21233.87.104.1 to 233.87.111.254233.87.111.2552,046
239233.87.112.0/21233.87.112.1 to 233.87.119.254233.87.119.2552,046
240233.87.120.0/21233.87.120.1 to 233.87.127.254233.87.127.2552,046
241233.87.128.0/21233.87.128.1 to 233.87.135.254233.87.135.2552,046
242233.87.136.0/21233.87.136.1 to 233.87.143.254233.87.143.2552,046
243233.87.144.0/21233.87.144.1 to 233.87.151.254233.87.151.2552,046
244233.87.152.0/21233.87.152.1 to 233.87.159.254233.87.159.2552,046
245233.87.160.0/21233.87.160.1 to 233.87.167.254233.87.167.2552,046
246233.87.168.0/21233.87.168.1 to 233.87.175.254233.87.175.2552,046
247233.87.176.0/21233.87.176.1 to 233.87.183.254233.87.183.2552,046
248233.87.184.0/21233.87.184.1 to 233.87.191.254233.87.191.2552,046
249233.87.192.0/21233.87.192.1 to 233.87.199.254233.87.199.2552,046
250233.87.200.0/21233.87.200.1 to 233.87.207.254233.87.207.2552,046
251233.87.208.0/21233.87.208.1 to 233.87.215.254233.87.215.2552,046
252233.87.216.0/21233.87.216.1 to 233.87.223.254233.87.223.2552,046
253233.87.224.0/21233.87.224.1 to 233.87.231.254233.87.231.2552,046
254233.87.232.0/21233.87.232.1 to 233.87.239.254233.87.239.2552,046
255233.87.240.0/21233.87.240.1 to 233.87.247.254233.87.247.2552,046
256233.87.248.0/21233.87.248.1 to 233.87.255.254233.87.255.2552,046

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.