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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.

Network255.0.0.0/11
Usable hosts2,097,150
Subnet mask255.224.0.0
Addresses2,097,152
Network address
255.0.0.0
Broadcast address
255.31.255.255
First usable
255.0.0.1
Last usable
255.31.255.254
Usable hosts
2,097,150 (2,097,152 less the network and broadcast addresses)
Subnet mask
255.224.0.0
Wildcard mask
0.31.255.255 (Cisco ACLs, OSPF)
Prefix length
/11
Type
Reserved 240.0.0.0/4
Future use; not usable on most systems
Old class
E (reserved)
As numbers
Hex FF000000 · Integer 4278190080 to 4280287231
Reverse DNS zones
0.255.in-addr.arpa
1.255.in-addr.arpa
2.255.in-addr.arpa
3.255.in-addr.arpa
4.255.in-addr.arpa
5.255.in-addr.arpa
6.255.in-addr.arpa
7.255.in-addr.arpa
8.255.in-addr.arpa
9.255.in-addr.arpa
10.255.in-addr.arpa
11.255.in-addr.arpa
12.255.in-addr.arpa
13.255.in-addr.arpa
14.255.in-addr.arpa
15.255.in-addr.arpa
and 16 more
/11 is not on a 8-bit boundary, so it takes 32 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11111111.00000000.00000000.00000000255.0.0.0
Subnet mask11111111.11100000.00000000.00000000255.224.0.0
Network11111111.00000000.00000000.00000000255.0.0.0
Broadcast11111111.00011111.11111111.11111111255.31.255.255
Split into smaller subnets/21
/12 (2)/13 (4)/14 (8)/15 (16)/16 (32)/17 (64)/18 (128)/19 (256)/20 (512)/21 (1,024)/22 (2,048)/23 (4,096)

255.0.0.0/11 makes 1,024 subnets of /21; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1255.0.0.0/21255.0.0.1 to 255.0.7.254255.0.7.2552,046
2255.0.8.0/21255.0.8.1 to 255.0.15.254255.0.15.2552,046
3255.0.16.0/21255.0.16.1 to 255.0.23.254255.0.23.2552,046
4255.0.24.0/21255.0.24.1 to 255.0.31.254255.0.31.2552,046
5255.0.32.0/21255.0.32.1 to 255.0.39.254255.0.39.2552,046
6255.0.40.0/21255.0.40.1 to 255.0.47.254255.0.47.2552,046
7255.0.48.0/21255.0.48.1 to 255.0.55.254255.0.55.2552,046
8255.0.56.0/21255.0.56.1 to 255.0.63.254255.0.63.2552,046
9255.0.64.0/21255.0.64.1 to 255.0.71.254255.0.71.2552,046
10255.0.72.0/21255.0.72.1 to 255.0.79.254255.0.79.2552,046
11255.0.80.0/21255.0.80.1 to 255.0.87.254255.0.87.2552,046
12255.0.88.0/21255.0.88.1 to 255.0.95.254255.0.95.2552,046
13255.0.96.0/21255.0.96.1 to 255.0.103.254255.0.103.2552,046
14255.0.104.0/21255.0.104.1 to 255.0.111.254255.0.111.2552,046
15255.0.112.0/21255.0.112.1 to 255.0.119.254255.0.119.2552,046
16255.0.120.0/21255.0.120.1 to 255.0.127.254255.0.127.2552,046
17255.0.128.0/21255.0.128.1 to 255.0.135.254255.0.135.2552,046
18255.0.136.0/21255.0.136.1 to 255.0.143.254255.0.143.2552,046
19255.0.144.0/21255.0.144.1 to 255.0.151.254255.0.151.2552,046
20255.0.152.0/21255.0.152.1 to 255.0.159.254255.0.159.2552,046
21255.0.160.0/21255.0.160.1 to 255.0.167.254255.0.167.2552,046
22255.0.168.0/21255.0.168.1 to 255.0.175.254255.0.175.2552,046
23255.0.176.0/21255.0.176.1 to 255.0.183.254255.0.183.2552,046
24255.0.184.0/21255.0.184.1 to 255.0.191.254255.0.191.2552,046
25255.0.192.0/21255.0.192.1 to 255.0.199.254255.0.199.2552,046
26255.0.200.0/21255.0.200.1 to 255.0.207.254255.0.207.2552,046
27255.0.208.0/21255.0.208.1 to 255.0.215.254255.0.215.2552,046
28255.0.216.0/21255.0.216.1 to 255.0.223.254255.0.223.2552,046
29255.0.224.0/21255.0.224.1 to 255.0.231.254255.0.231.2552,046
30255.0.232.0/21255.0.232.1 to 255.0.239.254255.0.239.2552,046
31255.0.240.0/21255.0.240.1 to 255.0.247.254255.0.247.2552,046
32255.0.248.0/21255.0.248.1 to 255.0.255.254255.0.255.2552,046
33255.1.0.0/21255.1.0.1 to 255.1.7.254255.1.7.2552,046
34255.1.8.0/21255.1.8.1 to 255.1.15.254255.1.15.2552,046
35255.1.16.0/21255.1.16.1 to 255.1.23.254255.1.23.2552,046
36255.1.24.0/21255.1.24.1 to 255.1.31.254255.1.31.2552,046
37255.1.32.0/21255.1.32.1 to 255.1.39.254255.1.39.2552,046
38255.1.40.0/21255.1.40.1 to 255.1.47.254255.1.47.2552,046
39255.1.48.0/21255.1.48.1 to 255.1.55.254255.1.55.2552,046
40255.1.56.0/21255.1.56.1 to 255.1.63.254255.1.63.2552,046
41255.1.64.0/21255.1.64.1 to 255.1.71.254255.1.71.2552,046
42255.1.72.0/21255.1.72.1 to 255.1.79.254255.1.79.2552,046
43255.1.80.0/21255.1.80.1 to 255.1.87.254255.1.87.2552,046
44255.1.88.0/21255.1.88.1 to 255.1.95.254255.1.95.2552,046
45255.1.96.0/21255.1.96.1 to 255.1.103.254255.1.103.2552,046
46255.1.104.0/21255.1.104.1 to 255.1.111.254255.1.111.2552,046
47255.1.112.0/21255.1.112.1 to 255.1.119.254255.1.119.2552,046
48255.1.120.0/21255.1.120.1 to 255.1.127.254255.1.127.2552,046
49255.1.128.0/21255.1.128.1 to 255.1.135.254255.1.135.2552,046
50255.1.136.0/21255.1.136.1 to 255.1.143.254255.1.143.2552,046
51255.1.144.0/21255.1.144.1 to 255.1.151.254255.1.151.2552,046
52255.1.152.0/21255.1.152.1 to 255.1.159.254255.1.159.2552,046
53255.1.160.0/21255.1.160.1 to 255.1.167.254255.1.167.2552,046
54255.1.168.0/21255.1.168.1 to 255.1.175.254255.1.175.2552,046
55255.1.176.0/21255.1.176.1 to 255.1.183.254255.1.183.2552,046
56255.1.184.0/21255.1.184.1 to 255.1.191.254255.1.191.2552,046
57255.1.192.0/21255.1.192.1 to 255.1.199.254255.1.199.2552,046
58255.1.200.0/21255.1.200.1 to 255.1.207.254255.1.207.2552,046
59255.1.208.0/21255.1.208.1 to 255.1.215.254255.1.215.2552,046
60255.1.216.0/21255.1.216.1 to 255.1.223.254255.1.223.2552,046
61255.1.224.0/21255.1.224.1 to 255.1.231.254255.1.231.2552,046
62255.1.232.0/21255.1.232.1 to 255.1.239.254255.1.239.2552,046
63255.1.240.0/21255.1.240.1 to 255.1.247.254255.1.247.2552,046
64255.1.248.0/21255.1.248.1 to 255.1.255.254255.1.255.2552,046
65255.2.0.0/21255.2.0.1 to 255.2.7.254255.2.7.2552,046
66255.2.8.0/21255.2.8.1 to 255.2.15.254255.2.15.2552,046
67255.2.16.0/21255.2.16.1 to 255.2.23.254255.2.23.2552,046
68255.2.24.0/21255.2.24.1 to 255.2.31.254255.2.31.2552,046
69255.2.32.0/21255.2.32.1 to 255.2.39.254255.2.39.2552,046
70255.2.40.0/21255.2.40.1 to 255.2.47.254255.2.47.2552,046
71255.2.48.0/21255.2.48.1 to 255.2.55.254255.2.55.2552,046
72255.2.56.0/21255.2.56.1 to 255.2.63.254255.2.63.2552,046
73255.2.64.0/21255.2.64.1 to 255.2.71.254255.2.71.2552,046
74255.2.72.0/21255.2.72.1 to 255.2.79.254255.2.79.2552,046
75255.2.80.0/21255.2.80.1 to 255.2.87.254255.2.87.2552,046
76255.2.88.0/21255.2.88.1 to 255.2.95.254255.2.95.2552,046
77255.2.96.0/21255.2.96.1 to 255.2.103.254255.2.103.2552,046
78255.2.104.0/21255.2.104.1 to 255.2.111.254255.2.111.2552,046
79255.2.112.0/21255.2.112.1 to 255.2.119.254255.2.119.2552,046
80255.2.120.0/21255.2.120.1 to 255.2.127.254255.2.127.2552,046
81255.2.128.0/21255.2.128.1 to 255.2.135.254255.2.135.2552,046
82255.2.136.0/21255.2.136.1 to 255.2.143.254255.2.143.2552,046
83255.2.144.0/21255.2.144.1 to 255.2.151.254255.2.151.2552,046
84255.2.152.0/21255.2.152.1 to 255.2.159.254255.2.159.2552,046
85255.2.160.0/21255.2.160.1 to 255.2.167.254255.2.167.2552,046
86255.2.168.0/21255.2.168.1 to 255.2.175.254255.2.175.2552,046
87255.2.176.0/21255.2.176.1 to 255.2.183.254255.2.183.2552,046
88255.2.184.0/21255.2.184.1 to 255.2.191.254255.2.191.2552,046
89255.2.192.0/21255.2.192.1 to 255.2.199.254255.2.199.2552,046
90255.2.200.0/21255.2.200.1 to 255.2.207.254255.2.207.2552,046
91255.2.208.0/21255.2.208.1 to 255.2.215.254255.2.215.2552,046
92255.2.216.0/21255.2.216.1 to 255.2.223.254255.2.223.2552,046
93255.2.224.0/21255.2.224.1 to 255.2.231.254255.2.231.2552,046
94255.2.232.0/21255.2.232.1 to 255.2.239.254255.2.239.2552,046
95255.2.240.0/21255.2.240.1 to 255.2.247.254255.2.247.2552,046
96255.2.248.0/21255.2.248.1 to 255.2.255.254255.2.255.2552,046
97255.3.0.0/21255.3.0.1 to 255.3.7.254255.3.7.2552,046
98255.3.8.0/21255.3.8.1 to 255.3.15.254255.3.15.2552,046
99255.3.16.0/21255.3.16.1 to 255.3.23.254255.3.23.2552,046
100255.3.24.0/21255.3.24.1 to 255.3.31.254255.3.31.2552,046
101255.3.32.0/21255.3.32.1 to 255.3.39.254255.3.39.2552,046
102255.3.40.0/21255.3.40.1 to 255.3.47.254255.3.47.2552,046
103255.3.48.0/21255.3.48.1 to 255.3.55.254255.3.55.2552,046
104255.3.56.0/21255.3.56.1 to 255.3.63.254255.3.63.2552,046
105255.3.64.0/21255.3.64.1 to 255.3.71.254255.3.71.2552,046
106255.3.72.0/21255.3.72.1 to 255.3.79.254255.3.79.2552,046
107255.3.80.0/21255.3.80.1 to 255.3.87.254255.3.87.2552,046
108255.3.88.0/21255.3.88.1 to 255.3.95.254255.3.95.2552,046
109255.3.96.0/21255.3.96.1 to 255.3.103.254255.3.103.2552,046
110255.3.104.0/21255.3.104.1 to 255.3.111.254255.3.111.2552,046
111255.3.112.0/21255.3.112.1 to 255.3.119.254255.3.119.2552,046
112255.3.120.0/21255.3.120.1 to 255.3.127.254255.3.127.2552,046
113255.3.128.0/21255.3.128.1 to 255.3.135.254255.3.135.2552,046
114255.3.136.0/21255.3.136.1 to 255.3.143.254255.3.143.2552,046
115255.3.144.0/21255.3.144.1 to 255.3.151.254255.3.151.2552,046
116255.3.152.0/21255.3.152.1 to 255.3.159.254255.3.159.2552,046
117255.3.160.0/21255.3.160.1 to 255.3.167.254255.3.167.2552,046
118255.3.168.0/21255.3.168.1 to 255.3.175.254255.3.175.2552,046
119255.3.176.0/21255.3.176.1 to 255.3.183.254255.3.183.2552,046
120255.3.184.0/21255.3.184.1 to 255.3.191.254255.3.191.2552,046
121255.3.192.0/21255.3.192.1 to 255.3.199.254255.3.199.2552,046
122255.3.200.0/21255.3.200.1 to 255.3.207.254255.3.207.2552,046
123255.3.208.0/21255.3.208.1 to 255.3.215.254255.3.215.2552,046
124255.3.216.0/21255.3.216.1 to 255.3.223.254255.3.223.2552,046
125255.3.224.0/21255.3.224.1 to 255.3.231.254255.3.231.2552,046
126255.3.232.0/21255.3.232.1 to 255.3.239.254255.3.239.2552,046
127255.3.240.0/21255.3.240.1 to 255.3.247.254255.3.247.2552,046
128255.3.248.0/21255.3.248.1 to 255.3.255.254255.3.255.2552,046
129255.4.0.0/21255.4.0.1 to 255.4.7.254255.4.7.2552,046
130255.4.8.0/21255.4.8.1 to 255.4.15.254255.4.15.2552,046
131255.4.16.0/21255.4.16.1 to 255.4.23.254255.4.23.2552,046
132255.4.24.0/21255.4.24.1 to 255.4.31.254255.4.31.2552,046
133255.4.32.0/21255.4.32.1 to 255.4.39.254255.4.39.2552,046
134255.4.40.0/21255.4.40.1 to 255.4.47.254255.4.47.2552,046
135255.4.48.0/21255.4.48.1 to 255.4.55.254255.4.55.2552,046
136255.4.56.0/21255.4.56.1 to 255.4.63.254255.4.63.2552,046
137255.4.64.0/21255.4.64.1 to 255.4.71.254255.4.71.2552,046
138255.4.72.0/21255.4.72.1 to 255.4.79.254255.4.79.2552,046
139255.4.80.0/21255.4.80.1 to 255.4.87.254255.4.87.2552,046
140255.4.88.0/21255.4.88.1 to 255.4.95.254255.4.95.2552,046
141255.4.96.0/21255.4.96.1 to 255.4.103.254255.4.103.2552,046
142255.4.104.0/21255.4.104.1 to 255.4.111.254255.4.111.2552,046
143255.4.112.0/21255.4.112.1 to 255.4.119.254255.4.119.2552,046
144255.4.120.0/21255.4.120.1 to 255.4.127.254255.4.127.2552,046
145255.4.128.0/21255.4.128.1 to 255.4.135.254255.4.135.2552,046
146255.4.136.0/21255.4.136.1 to 255.4.143.254255.4.143.2552,046
147255.4.144.0/21255.4.144.1 to 255.4.151.254255.4.151.2552,046
148255.4.152.0/21255.4.152.1 to 255.4.159.254255.4.159.2552,046
149255.4.160.0/21255.4.160.1 to 255.4.167.254255.4.167.2552,046
150255.4.168.0/21255.4.168.1 to 255.4.175.254255.4.175.2552,046
151255.4.176.0/21255.4.176.1 to 255.4.183.254255.4.183.2552,046
152255.4.184.0/21255.4.184.1 to 255.4.191.254255.4.191.2552,046
153255.4.192.0/21255.4.192.1 to 255.4.199.254255.4.199.2552,046
154255.4.200.0/21255.4.200.1 to 255.4.207.254255.4.207.2552,046
155255.4.208.0/21255.4.208.1 to 255.4.215.254255.4.215.2552,046
156255.4.216.0/21255.4.216.1 to 255.4.223.254255.4.223.2552,046
157255.4.224.0/21255.4.224.1 to 255.4.231.254255.4.231.2552,046
158255.4.232.0/21255.4.232.1 to 255.4.239.254255.4.239.2552,046
159255.4.240.0/21255.4.240.1 to 255.4.247.254255.4.247.2552,046
160255.4.248.0/21255.4.248.1 to 255.4.255.254255.4.255.2552,046
161255.5.0.0/21255.5.0.1 to 255.5.7.254255.5.7.2552,046
162255.5.8.0/21255.5.8.1 to 255.5.15.254255.5.15.2552,046
163255.5.16.0/21255.5.16.1 to 255.5.23.254255.5.23.2552,046
164255.5.24.0/21255.5.24.1 to 255.5.31.254255.5.31.2552,046
165255.5.32.0/21255.5.32.1 to 255.5.39.254255.5.39.2552,046
166255.5.40.0/21255.5.40.1 to 255.5.47.254255.5.47.2552,046
167255.5.48.0/21255.5.48.1 to 255.5.55.254255.5.55.2552,046
168255.5.56.0/21255.5.56.1 to 255.5.63.254255.5.63.2552,046
169255.5.64.0/21255.5.64.1 to 255.5.71.254255.5.71.2552,046
170255.5.72.0/21255.5.72.1 to 255.5.79.254255.5.79.2552,046
171255.5.80.0/21255.5.80.1 to 255.5.87.254255.5.87.2552,046
172255.5.88.0/21255.5.88.1 to 255.5.95.254255.5.95.2552,046
173255.5.96.0/21255.5.96.1 to 255.5.103.254255.5.103.2552,046
174255.5.104.0/21255.5.104.1 to 255.5.111.254255.5.111.2552,046
175255.5.112.0/21255.5.112.1 to 255.5.119.254255.5.119.2552,046
176255.5.120.0/21255.5.120.1 to 255.5.127.254255.5.127.2552,046
177255.5.128.0/21255.5.128.1 to 255.5.135.254255.5.135.2552,046
178255.5.136.0/21255.5.136.1 to 255.5.143.254255.5.143.2552,046
179255.5.144.0/21255.5.144.1 to 255.5.151.254255.5.151.2552,046
180255.5.152.0/21255.5.152.1 to 255.5.159.254255.5.159.2552,046
181255.5.160.0/21255.5.160.1 to 255.5.167.254255.5.167.2552,046
182255.5.168.0/21255.5.168.1 to 255.5.175.254255.5.175.2552,046
183255.5.176.0/21255.5.176.1 to 255.5.183.254255.5.183.2552,046
184255.5.184.0/21255.5.184.1 to 255.5.191.254255.5.191.2552,046
185255.5.192.0/21255.5.192.1 to 255.5.199.254255.5.199.2552,046
186255.5.200.0/21255.5.200.1 to 255.5.207.254255.5.207.2552,046
187255.5.208.0/21255.5.208.1 to 255.5.215.254255.5.215.2552,046
188255.5.216.0/21255.5.216.1 to 255.5.223.254255.5.223.2552,046
189255.5.224.0/21255.5.224.1 to 255.5.231.254255.5.231.2552,046
190255.5.232.0/21255.5.232.1 to 255.5.239.254255.5.239.2552,046
191255.5.240.0/21255.5.240.1 to 255.5.247.254255.5.247.2552,046
192255.5.248.0/21255.5.248.1 to 255.5.255.254255.5.255.2552,046
193255.6.0.0/21255.6.0.1 to 255.6.7.254255.6.7.2552,046
194255.6.8.0/21255.6.8.1 to 255.6.15.254255.6.15.2552,046
195255.6.16.0/21255.6.16.1 to 255.6.23.254255.6.23.2552,046
196255.6.24.0/21255.6.24.1 to 255.6.31.254255.6.31.2552,046
197255.6.32.0/21255.6.32.1 to 255.6.39.254255.6.39.2552,046
198255.6.40.0/21255.6.40.1 to 255.6.47.254255.6.47.2552,046
199255.6.48.0/21255.6.48.1 to 255.6.55.254255.6.55.2552,046
200255.6.56.0/21255.6.56.1 to 255.6.63.254255.6.63.2552,046
201255.6.64.0/21255.6.64.1 to 255.6.71.254255.6.71.2552,046
202255.6.72.0/21255.6.72.1 to 255.6.79.254255.6.79.2552,046
203255.6.80.0/21255.6.80.1 to 255.6.87.254255.6.87.2552,046
204255.6.88.0/21255.6.88.1 to 255.6.95.254255.6.95.2552,046
205255.6.96.0/21255.6.96.1 to 255.6.103.254255.6.103.2552,046
206255.6.104.0/21255.6.104.1 to 255.6.111.254255.6.111.2552,046
207255.6.112.0/21255.6.112.1 to 255.6.119.254255.6.119.2552,046
208255.6.120.0/21255.6.120.1 to 255.6.127.254255.6.127.2552,046
209255.6.128.0/21255.6.128.1 to 255.6.135.254255.6.135.2552,046
210255.6.136.0/21255.6.136.1 to 255.6.143.254255.6.143.2552,046
211255.6.144.0/21255.6.144.1 to 255.6.151.254255.6.151.2552,046
212255.6.152.0/21255.6.152.1 to 255.6.159.254255.6.159.2552,046
213255.6.160.0/21255.6.160.1 to 255.6.167.254255.6.167.2552,046
214255.6.168.0/21255.6.168.1 to 255.6.175.254255.6.175.2552,046
215255.6.176.0/21255.6.176.1 to 255.6.183.254255.6.183.2552,046
216255.6.184.0/21255.6.184.1 to 255.6.191.254255.6.191.2552,046
217255.6.192.0/21255.6.192.1 to 255.6.199.254255.6.199.2552,046
218255.6.200.0/21255.6.200.1 to 255.6.207.254255.6.207.2552,046
219255.6.208.0/21255.6.208.1 to 255.6.215.254255.6.215.2552,046
220255.6.216.0/21255.6.216.1 to 255.6.223.254255.6.223.2552,046
221255.6.224.0/21255.6.224.1 to 255.6.231.254255.6.231.2552,046
222255.6.232.0/21255.6.232.1 to 255.6.239.254255.6.239.2552,046
223255.6.240.0/21255.6.240.1 to 255.6.247.254255.6.247.2552,046
224255.6.248.0/21255.6.248.1 to 255.6.255.254255.6.255.2552,046
225255.7.0.0/21255.7.0.1 to 255.7.7.254255.7.7.2552,046
226255.7.8.0/21255.7.8.1 to 255.7.15.254255.7.15.2552,046
227255.7.16.0/21255.7.16.1 to 255.7.23.254255.7.23.2552,046
228255.7.24.0/21255.7.24.1 to 255.7.31.254255.7.31.2552,046
229255.7.32.0/21255.7.32.1 to 255.7.39.254255.7.39.2552,046
230255.7.40.0/21255.7.40.1 to 255.7.47.254255.7.47.2552,046
231255.7.48.0/21255.7.48.1 to 255.7.55.254255.7.55.2552,046
232255.7.56.0/21255.7.56.1 to 255.7.63.254255.7.63.2552,046
233255.7.64.0/21255.7.64.1 to 255.7.71.254255.7.71.2552,046
234255.7.72.0/21255.7.72.1 to 255.7.79.254255.7.79.2552,046
235255.7.80.0/21255.7.80.1 to 255.7.87.254255.7.87.2552,046
236255.7.88.0/21255.7.88.1 to 255.7.95.254255.7.95.2552,046
237255.7.96.0/21255.7.96.1 to 255.7.103.254255.7.103.2552,046
238255.7.104.0/21255.7.104.1 to 255.7.111.254255.7.111.2552,046
239255.7.112.0/21255.7.112.1 to 255.7.119.254255.7.119.2552,046
240255.7.120.0/21255.7.120.1 to 255.7.127.254255.7.127.2552,046
241255.7.128.0/21255.7.128.1 to 255.7.135.254255.7.135.2552,046
242255.7.136.0/21255.7.136.1 to 255.7.143.254255.7.143.2552,046
243255.7.144.0/21255.7.144.1 to 255.7.151.254255.7.151.2552,046
244255.7.152.0/21255.7.152.1 to 255.7.159.254255.7.159.2552,046
245255.7.160.0/21255.7.160.1 to 255.7.167.254255.7.167.2552,046
246255.7.168.0/21255.7.168.1 to 255.7.175.254255.7.175.2552,046
247255.7.176.0/21255.7.176.1 to 255.7.183.254255.7.183.2552,046
248255.7.184.0/21255.7.184.1 to 255.7.191.254255.7.191.2552,046
249255.7.192.0/21255.7.192.1 to 255.7.199.254255.7.199.2552,046
250255.7.200.0/21255.7.200.1 to 255.7.207.254255.7.207.2552,046
251255.7.208.0/21255.7.208.1 to 255.7.215.254255.7.215.2552,046
252255.7.216.0/21255.7.216.1 to 255.7.223.254255.7.223.2552,046
253255.7.224.0/21255.7.224.1 to 255.7.231.254255.7.231.2552,046
254255.7.232.0/21255.7.232.1 to 255.7.239.254255.7.239.2552,046
255255.7.240.0/21255.7.240.1 to 255.7.247.254255.7.247.2552,046
256255.7.248.0/21255.7.248.1 to 255.7.255.254255.7.255.2552,046

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.