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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.

Network231.80.0.0/12
Usable hosts1,048,574
Subnet mask255.240.0.0
Addresses1,048,576
Network address
231.80.0.0
Broadcast address
231.95.255.255
First usable
231.80.0.1
Last usable
231.95.255.254
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 E7500000 · Integer 3880779776 to 3881828351
Reverse DNS zones
80.231.in-addr.arpa
81.231.in-addr.arpa
82.231.in-addr.arpa
83.231.in-addr.arpa
84.231.in-addr.arpa
85.231.in-addr.arpa
86.231.in-addr.arpa
87.231.in-addr.arpa
88.231.in-addr.arpa
89.231.in-addr.arpa
90.231.in-addr.arpa
91.231.in-addr.arpa
92.231.in-addr.arpa
93.231.in-addr.arpa
94.231.in-addr.arpa
95.231.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
Address11100111.01010000.00000000.00000000231.80.0.0
Subnet mask11111111.11110000.00000000.00000000255.240.0.0
Network11100111.01010000.00000000.00000000231.80.0.0
Broadcast11100111.01011111.11111111.11111111231.95.255.255
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)

231.80.0.0/12 makes 512 subnets of /21; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1231.80.0.0/21231.80.0.1 to 231.80.7.254231.80.7.2552,046
2231.80.8.0/21231.80.8.1 to 231.80.15.254231.80.15.2552,046
3231.80.16.0/21231.80.16.1 to 231.80.23.254231.80.23.2552,046
4231.80.24.0/21231.80.24.1 to 231.80.31.254231.80.31.2552,046
5231.80.32.0/21231.80.32.1 to 231.80.39.254231.80.39.2552,046
6231.80.40.0/21231.80.40.1 to 231.80.47.254231.80.47.2552,046
7231.80.48.0/21231.80.48.1 to 231.80.55.254231.80.55.2552,046
8231.80.56.0/21231.80.56.1 to 231.80.63.254231.80.63.2552,046
9231.80.64.0/21231.80.64.1 to 231.80.71.254231.80.71.2552,046
10231.80.72.0/21231.80.72.1 to 231.80.79.254231.80.79.2552,046
11231.80.80.0/21231.80.80.1 to 231.80.87.254231.80.87.2552,046
12231.80.88.0/21231.80.88.1 to 231.80.95.254231.80.95.2552,046
13231.80.96.0/21231.80.96.1 to 231.80.103.254231.80.103.2552,046
14231.80.104.0/21231.80.104.1 to 231.80.111.254231.80.111.2552,046
15231.80.112.0/21231.80.112.1 to 231.80.119.254231.80.119.2552,046
16231.80.120.0/21231.80.120.1 to 231.80.127.254231.80.127.2552,046
17231.80.128.0/21231.80.128.1 to 231.80.135.254231.80.135.2552,046
18231.80.136.0/21231.80.136.1 to 231.80.143.254231.80.143.2552,046
19231.80.144.0/21231.80.144.1 to 231.80.151.254231.80.151.2552,046
20231.80.152.0/21231.80.152.1 to 231.80.159.254231.80.159.2552,046
21231.80.160.0/21231.80.160.1 to 231.80.167.254231.80.167.2552,046
22231.80.168.0/21231.80.168.1 to 231.80.175.254231.80.175.2552,046
23231.80.176.0/21231.80.176.1 to 231.80.183.254231.80.183.2552,046
24231.80.184.0/21231.80.184.1 to 231.80.191.254231.80.191.2552,046
25231.80.192.0/21231.80.192.1 to 231.80.199.254231.80.199.2552,046
26231.80.200.0/21231.80.200.1 to 231.80.207.254231.80.207.2552,046
27231.80.208.0/21231.80.208.1 to 231.80.215.254231.80.215.2552,046
28231.80.216.0/21231.80.216.1 to 231.80.223.254231.80.223.2552,046
29231.80.224.0/21231.80.224.1 to 231.80.231.254231.80.231.2552,046
30231.80.232.0/21231.80.232.1 to 231.80.239.254231.80.239.2552,046
31231.80.240.0/21231.80.240.1 to 231.80.247.254231.80.247.2552,046
32231.80.248.0/21231.80.248.1 to 231.80.255.254231.80.255.2552,046
33231.81.0.0/21231.81.0.1 to 231.81.7.254231.81.7.2552,046
34231.81.8.0/21231.81.8.1 to 231.81.15.254231.81.15.2552,046
35231.81.16.0/21231.81.16.1 to 231.81.23.254231.81.23.2552,046
36231.81.24.0/21231.81.24.1 to 231.81.31.254231.81.31.2552,046
37231.81.32.0/21231.81.32.1 to 231.81.39.254231.81.39.2552,046
38231.81.40.0/21231.81.40.1 to 231.81.47.254231.81.47.2552,046
39231.81.48.0/21231.81.48.1 to 231.81.55.254231.81.55.2552,046
40231.81.56.0/21231.81.56.1 to 231.81.63.254231.81.63.2552,046
41231.81.64.0/21231.81.64.1 to 231.81.71.254231.81.71.2552,046
42231.81.72.0/21231.81.72.1 to 231.81.79.254231.81.79.2552,046
43231.81.80.0/21231.81.80.1 to 231.81.87.254231.81.87.2552,046
44231.81.88.0/21231.81.88.1 to 231.81.95.254231.81.95.2552,046
45231.81.96.0/21231.81.96.1 to 231.81.103.254231.81.103.2552,046
46231.81.104.0/21231.81.104.1 to 231.81.111.254231.81.111.2552,046
47231.81.112.0/21231.81.112.1 to 231.81.119.254231.81.119.2552,046
48231.81.120.0/21231.81.120.1 to 231.81.127.254231.81.127.2552,046
49231.81.128.0/21231.81.128.1 to 231.81.135.254231.81.135.2552,046
50231.81.136.0/21231.81.136.1 to 231.81.143.254231.81.143.2552,046
51231.81.144.0/21231.81.144.1 to 231.81.151.254231.81.151.2552,046
52231.81.152.0/21231.81.152.1 to 231.81.159.254231.81.159.2552,046
53231.81.160.0/21231.81.160.1 to 231.81.167.254231.81.167.2552,046
54231.81.168.0/21231.81.168.1 to 231.81.175.254231.81.175.2552,046
55231.81.176.0/21231.81.176.1 to 231.81.183.254231.81.183.2552,046
56231.81.184.0/21231.81.184.1 to 231.81.191.254231.81.191.2552,046
57231.81.192.0/21231.81.192.1 to 231.81.199.254231.81.199.2552,046
58231.81.200.0/21231.81.200.1 to 231.81.207.254231.81.207.2552,046
59231.81.208.0/21231.81.208.1 to 231.81.215.254231.81.215.2552,046
60231.81.216.0/21231.81.216.1 to 231.81.223.254231.81.223.2552,046
61231.81.224.0/21231.81.224.1 to 231.81.231.254231.81.231.2552,046
62231.81.232.0/21231.81.232.1 to 231.81.239.254231.81.239.2552,046
63231.81.240.0/21231.81.240.1 to 231.81.247.254231.81.247.2552,046
64231.81.248.0/21231.81.248.1 to 231.81.255.254231.81.255.2552,046
65231.82.0.0/21231.82.0.1 to 231.82.7.254231.82.7.2552,046
66231.82.8.0/21231.82.8.1 to 231.82.15.254231.82.15.2552,046
67231.82.16.0/21231.82.16.1 to 231.82.23.254231.82.23.2552,046
68231.82.24.0/21231.82.24.1 to 231.82.31.254231.82.31.2552,046
69231.82.32.0/21231.82.32.1 to 231.82.39.254231.82.39.2552,046
70231.82.40.0/21231.82.40.1 to 231.82.47.254231.82.47.2552,046
71231.82.48.0/21231.82.48.1 to 231.82.55.254231.82.55.2552,046
72231.82.56.0/21231.82.56.1 to 231.82.63.254231.82.63.2552,046
73231.82.64.0/21231.82.64.1 to 231.82.71.254231.82.71.2552,046
74231.82.72.0/21231.82.72.1 to 231.82.79.254231.82.79.2552,046
75231.82.80.0/21231.82.80.1 to 231.82.87.254231.82.87.2552,046
76231.82.88.0/21231.82.88.1 to 231.82.95.254231.82.95.2552,046
77231.82.96.0/21231.82.96.1 to 231.82.103.254231.82.103.2552,046
78231.82.104.0/21231.82.104.1 to 231.82.111.254231.82.111.2552,046
79231.82.112.0/21231.82.112.1 to 231.82.119.254231.82.119.2552,046
80231.82.120.0/21231.82.120.1 to 231.82.127.254231.82.127.2552,046
81231.82.128.0/21231.82.128.1 to 231.82.135.254231.82.135.2552,046
82231.82.136.0/21231.82.136.1 to 231.82.143.254231.82.143.2552,046
83231.82.144.0/21231.82.144.1 to 231.82.151.254231.82.151.2552,046
84231.82.152.0/21231.82.152.1 to 231.82.159.254231.82.159.2552,046
85231.82.160.0/21231.82.160.1 to 231.82.167.254231.82.167.2552,046
86231.82.168.0/21231.82.168.1 to 231.82.175.254231.82.175.2552,046
87231.82.176.0/21231.82.176.1 to 231.82.183.254231.82.183.2552,046
88231.82.184.0/21231.82.184.1 to 231.82.191.254231.82.191.2552,046
89231.82.192.0/21231.82.192.1 to 231.82.199.254231.82.199.2552,046
90231.82.200.0/21231.82.200.1 to 231.82.207.254231.82.207.2552,046
91231.82.208.0/21231.82.208.1 to 231.82.215.254231.82.215.2552,046
92231.82.216.0/21231.82.216.1 to 231.82.223.254231.82.223.2552,046
93231.82.224.0/21231.82.224.1 to 231.82.231.254231.82.231.2552,046
94231.82.232.0/21231.82.232.1 to 231.82.239.254231.82.239.2552,046
95231.82.240.0/21231.82.240.1 to 231.82.247.254231.82.247.2552,046
96231.82.248.0/21231.82.248.1 to 231.82.255.254231.82.255.2552,046
97231.83.0.0/21231.83.0.1 to 231.83.7.254231.83.7.2552,046
98231.83.8.0/21231.83.8.1 to 231.83.15.254231.83.15.2552,046
99231.83.16.0/21231.83.16.1 to 231.83.23.254231.83.23.2552,046
100231.83.24.0/21231.83.24.1 to 231.83.31.254231.83.31.2552,046
101231.83.32.0/21231.83.32.1 to 231.83.39.254231.83.39.2552,046
102231.83.40.0/21231.83.40.1 to 231.83.47.254231.83.47.2552,046
103231.83.48.0/21231.83.48.1 to 231.83.55.254231.83.55.2552,046
104231.83.56.0/21231.83.56.1 to 231.83.63.254231.83.63.2552,046
105231.83.64.0/21231.83.64.1 to 231.83.71.254231.83.71.2552,046
106231.83.72.0/21231.83.72.1 to 231.83.79.254231.83.79.2552,046
107231.83.80.0/21231.83.80.1 to 231.83.87.254231.83.87.2552,046
108231.83.88.0/21231.83.88.1 to 231.83.95.254231.83.95.2552,046
109231.83.96.0/21231.83.96.1 to 231.83.103.254231.83.103.2552,046
110231.83.104.0/21231.83.104.1 to 231.83.111.254231.83.111.2552,046
111231.83.112.0/21231.83.112.1 to 231.83.119.254231.83.119.2552,046
112231.83.120.0/21231.83.120.1 to 231.83.127.254231.83.127.2552,046
113231.83.128.0/21231.83.128.1 to 231.83.135.254231.83.135.2552,046
114231.83.136.0/21231.83.136.1 to 231.83.143.254231.83.143.2552,046
115231.83.144.0/21231.83.144.1 to 231.83.151.254231.83.151.2552,046
116231.83.152.0/21231.83.152.1 to 231.83.159.254231.83.159.2552,046
117231.83.160.0/21231.83.160.1 to 231.83.167.254231.83.167.2552,046
118231.83.168.0/21231.83.168.1 to 231.83.175.254231.83.175.2552,046
119231.83.176.0/21231.83.176.1 to 231.83.183.254231.83.183.2552,046
120231.83.184.0/21231.83.184.1 to 231.83.191.254231.83.191.2552,046
121231.83.192.0/21231.83.192.1 to 231.83.199.254231.83.199.2552,046
122231.83.200.0/21231.83.200.1 to 231.83.207.254231.83.207.2552,046
123231.83.208.0/21231.83.208.1 to 231.83.215.254231.83.215.2552,046
124231.83.216.0/21231.83.216.1 to 231.83.223.254231.83.223.2552,046
125231.83.224.0/21231.83.224.1 to 231.83.231.254231.83.231.2552,046
126231.83.232.0/21231.83.232.1 to 231.83.239.254231.83.239.2552,046
127231.83.240.0/21231.83.240.1 to 231.83.247.254231.83.247.2552,046
128231.83.248.0/21231.83.248.1 to 231.83.255.254231.83.255.2552,046
129231.84.0.0/21231.84.0.1 to 231.84.7.254231.84.7.2552,046
130231.84.8.0/21231.84.8.1 to 231.84.15.254231.84.15.2552,046
131231.84.16.0/21231.84.16.1 to 231.84.23.254231.84.23.2552,046
132231.84.24.0/21231.84.24.1 to 231.84.31.254231.84.31.2552,046
133231.84.32.0/21231.84.32.1 to 231.84.39.254231.84.39.2552,046
134231.84.40.0/21231.84.40.1 to 231.84.47.254231.84.47.2552,046
135231.84.48.0/21231.84.48.1 to 231.84.55.254231.84.55.2552,046
136231.84.56.0/21231.84.56.1 to 231.84.63.254231.84.63.2552,046
137231.84.64.0/21231.84.64.1 to 231.84.71.254231.84.71.2552,046
138231.84.72.0/21231.84.72.1 to 231.84.79.254231.84.79.2552,046
139231.84.80.0/21231.84.80.1 to 231.84.87.254231.84.87.2552,046
140231.84.88.0/21231.84.88.1 to 231.84.95.254231.84.95.2552,046
141231.84.96.0/21231.84.96.1 to 231.84.103.254231.84.103.2552,046
142231.84.104.0/21231.84.104.1 to 231.84.111.254231.84.111.2552,046
143231.84.112.0/21231.84.112.1 to 231.84.119.254231.84.119.2552,046
144231.84.120.0/21231.84.120.1 to 231.84.127.254231.84.127.2552,046
145231.84.128.0/21231.84.128.1 to 231.84.135.254231.84.135.2552,046
146231.84.136.0/21231.84.136.1 to 231.84.143.254231.84.143.2552,046
147231.84.144.0/21231.84.144.1 to 231.84.151.254231.84.151.2552,046
148231.84.152.0/21231.84.152.1 to 231.84.159.254231.84.159.2552,046
149231.84.160.0/21231.84.160.1 to 231.84.167.254231.84.167.2552,046
150231.84.168.0/21231.84.168.1 to 231.84.175.254231.84.175.2552,046
151231.84.176.0/21231.84.176.1 to 231.84.183.254231.84.183.2552,046
152231.84.184.0/21231.84.184.1 to 231.84.191.254231.84.191.2552,046
153231.84.192.0/21231.84.192.1 to 231.84.199.254231.84.199.2552,046
154231.84.200.0/21231.84.200.1 to 231.84.207.254231.84.207.2552,046
155231.84.208.0/21231.84.208.1 to 231.84.215.254231.84.215.2552,046
156231.84.216.0/21231.84.216.1 to 231.84.223.254231.84.223.2552,046
157231.84.224.0/21231.84.224.1 to 231.84.231.254231.84.231.2552,046
158231.84.232.0/21231.84.232.1 to 231.84.239.254231.84.239.2552,046
159231.84.240.0/21231.84.240.1 to 231.84.247.254231.84.247.2552,046
160231.84.248.0/21231.84.248.1 to 231.84.255.254231.84.255.2552,046
161231.85.0.0/21231.85.0.1 to 231.85.7.254231.85.7.2552,046
162231.85.8.0/21231.85.8.1 to 231.85.15.254231.85.15.2552,046
163231.85.16.0/21231.85.16.1 to 231.85.23.254231.85.23.2552,046
164231.85.24.0/21231.85.24.1 to 231.85.31.254231.85.31.2552,046
165231.85.32.0/21231.85.32.1 to 231.85.39.254231.85.39.2552,046
166231.85.40.0/21231.85.40.1 to 231.85.47.254231.85.47.2552,046
167231.85.48.0/21231.85.48.1 to 231.85.55.254231.85.55.2552,046
168231.85.56.0/21231.85.56.1 to 231.85.63.254231.85.63.2552,046
169231.85.64.0/21231.85.64.1 to 231.85.71.254231.85.71.2552,046
170231.85.72.0/21231.85.72.1 to 231.85.79.254231.85.79.2552,046
171231.85.80.0/21231.85.80.1 to 231.85.87.254231.85.87.2552,046
172231.85.88.0/21231.85.88.1 to 231.85.95.254231.85.95.2552,046
173231.85.96.0/21231.85.96.1 to 231.85.103.254231.85.103.2552,046
174231.85.104.0/21231.85.104.1 to 231.85.111.254231.85.111.2552,046
175231.85.112.0/21231.85.112.1 to 231.85.119.254231.85.119.2552,046
176231.85.120.0/21231.85.120.1 to 231.85.127.254231.85.127.2552,046
177231.85.128.0/21231.85.128.1 to 231.85.135.254231.85.135.2552,046
178231.85.136.0/21231.85.136.1 to 231.85.143.254231.85.143.2552,046
179231.85.144.0/21231.85.144.1 to 231.85.151.254231.85.151.2552,046
180231.85.152.0/21231.85.152.1 to 231.85.159.254231.85.159.2552,046
181231.85.160.0/21231.85.160.1 to 231.85.167.254231.85.167.2552,046
182231.85.168.0/21231.85.168.1 to 231.85.175.254231.85.175.2552,046
183231.85.176.0/21231.85.176.1 to 231.85.183.254231.85.183.2552,046
184231.85.184.0/21231.85.184.1 to 231.85.191.254231.85.191.2552,046
185231.85.192.0/21231.85.192.1 to 231.85.199.254231.85.199.2552,046
186231.85.200.0/21231.85.200.1 to 231.85.207.254231.85.207.2552,046
187231.85.208.0/21231.85.208.1 to 231.85.215.254231.85.215.2552,046
188231.85.216.0/21231.85.216.1 to 231.85.223.254231.85.223.2552,046
189231.85.224.0/21231.85.224.1 to 231.85.231.254231.85.231.2552,046
190231.85.232.0/21231.85.232.1 to 231.85.239.254231.85.239.2552,046
191231.85.240.0/21231.85.240.1 to 231.85.247.254231.85.247.2552,046
192231.85.248.0/21231.85.248.1 to 231.85.255.254231.85.255.2552,046
193231.86.0.0/21231.86.0.1 to 231.86.7.254231.86.7.2552,046
194231.86.8.0/21231.86.8.1 to 231.86.15.254231.86.15.2552,046
195231.86.16.0/21231.86.16.1 to 231.86.23.254231.86.23.2552,046
196231.86.24.0/21231.86.24.1 to 231.86.31.254231.86.31.2552,046
197231.86.32.0/21231.86.32.1 to 231.86.39.254231.86.39.2552,046
198231.86.40.0/21231.86.40.1 to 231.86.47.254231.86.47.2552,046
199231.86.48.0/21231.86.48.1 to 231.86.55.254231.86.55.2552,046
200231.86.56.0/21231.86.56.1 to 231.86.63.254231.86.63.2552,046
201231.86.64.0/21231.86.64.1 to 231.86.71.254231.86.71.2552,046
202231.86.72.0/21231.86.72.1 to 231.86.79.254231.86.79.2552,046
203231.86.80.0/21231.86.80.1 to 231.86.87.254231.86.87.2552,046
204231.86.88.0/21231.86.88.1 to 231.86.95.254231.86.95.2552,046
205231.86.96.0/21231.86.96.1 to 231.86.103.254231.86.103.2552,046
206231.86.104.0/21231.86.104.1 to 231.86.111.254231.86.111.2552,046
207231.86.112.0/21231.86.112.1 to 231.86.119.254231.86.119.2552,046
208231.86.120.0/21231.86.120.1 to 231.86.127.254231.86.127.2552,046
209231.86.128.0/21231.86.128.1 to 231.86.135.254231.86.135.2552,046
210231.86.136.0/21231.86.136.1 to 231.86.143.254231.86.143.2552,046
211231.86.144.0/21231.86.144.1 to 231.86.151.254231.86.151.2552,046
212231.86.152.0/21231.86.152.1 to 231.86.159.254231.86.159.2552,046
213231.86.160.0/21231.86.160.1 to 231.86.167.254231.86.167.2552,046
214231.86.168.0/21231.86.168.1 to 231.86.175.254231.86.175.2552,046
215231.86.176.0/21231.86.176.1 to 231.86.183.254231.86.183.2552,046
216231.86.184.0/21231.86.184.1 to 231.86.191.254231.86.191.2552,046
217231.86.192.0/21231.86.192.1 to 231.86.199.254231.86.199.2552,046
218231.86.200.0/21231.86.200.1 to 231.86.207.254231.86.207.2552,046
219231.86.208.0/21231.86.208.1 to 231.86.215.254231.86.215.2552,046
220231.86.216.0/21231.86.216.1 to 231.86.223.254231.86.223.2552,046
221231.86.224.0/21231.86.224.1 to 231.86.231.254231.86.231.2552,046
222231.86.232.0/21231.86.232.1 to 231.86.239.254231.86.239.2552,046
223231.86.240.0/21231.86.240.1 to 231.86.247.254231.86.247.2552,046
224231.86.248.0/21231.86.248.1 to 231.86.255.254231.86.255.2552,046
225231.87.0.0/21231.87.0.1 to 231.87.7.254231.87.7.2552,046
226231.87.8.0/21231.87.8.1 to 231.87.15.254231.87.15.2552,046
227231.87.16.0/21231.87.16.1 to 231.87.23.254231.87.23.2552,046
228231.87.24.0/21231.87.24.1 to 231.87.31.254231.87.31.2552,046
229231.87.32.0/21231.87.32.1 to 231.87.39.254231.87.39.2552,046
230231.87.40.0/21231.87.40.1 to 231.87.47.254231.87.47.2552,046
231231.87.48.0/21231.87.48.1 to 231.87.55.254231.87.55.2552,046
232231.87.56.0/21231.87.56.1 to 231.87.63.254231.87.63.2552,046
233231.87.64.0/21231.87.64.1 to 231.87.71.254231.87.71.2552,046
234231.87.72.0/21231.87.72.1 to 231.87.79.254231.87.79.2552,046
235231.87.80.0/21231.87.80.1 to 231.87.87.254231.87.87.2552,046
236231.87.88.0/21231.87.88.1 to 231.87.95.254231.87.95.2552,046
237231.87.96.0/21231.87.96.1 to 231.87.103.254231.87.103.2552,046
238231.87.104.0/21231.87.104.1 to 231.87.111.254231.87.111.2552,046
239231.87.112.0/21231.87.112.1 to 231.87.119.254231.87.119.2552,046
240231.87.120.0/21231.87.120.1 to 231.87.127.254231.87.127.2552,046
241231.87.128.0/21231.87.128.1 to 231.87.135.254231.87.135.2552,046
242231.87.136.0/21231.87.136.1 to 231.87.143.254231.87.143.2552,046
243231.87.144.0/21231.87.144.1 to 231.87.151.254231.87.151.2552,046
244231.87.152.0/21231.87.152.1 to 231.87.159.254231.87.159.2552,046
245231.87.160.0/21231.87.160.1 to 231.87.167.254231.87.167.2552,046
246231.87.168.0/21231.87.168.1 to 231.87.175.254231.87.175.2552,046
247231.87.176.0/21231.87.176.1 to 231.87.183.254231.87.183.2552,046
248231.87.184.0/21231.87.184.1 to 231.87.191.254231.87.191.2552,046
249231.87.192.0/21231.87.192.1 to 231.87.199.254231.87.199.2552,046
250231.87.200.0/21231.87.200.1 to 231.87.207.254231.87.207.2552,046
251231.87.208.0/21231.87.208.1 to 231.87.215.254231.87.215.2552,046
252231.87.216.0/21231.87.216.1 to 231.87.223.254231.87.223.2552,046
253231.87.224.0/21231.87.224.1 to 231.87.231.254231.87.231.2552,046
254231.87.232.0/21231.87.232.1 to 231.87.239.254231.87.239.2552,046
255231.87.240.0/21231.87.240.1 to 231.87.247.254231.87.247.2552,046
256231.87.248.0/21231.87.248.1 to 231.87.255.254231.87.255.2552,046

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.