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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.

Network127.208.0.0/12
Usable hosts1,048,574
Subnet mask255.240.0.0
Addresses1,048,576
Network address
127.208.0.0
Broadcast address
127.223.255.255
First usable
127.208.0.1
Last usable
127.223.255.254
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
Loopback 127.0.0.0/8
This computer
Old class
A (default /8)
As numbers
Hex 7FD00000 · Integer 2144337920 to 2145386495
Reverse DNS zones
208.127.in-addr.arpa
209.127.in-addr.arpa
210.127.in-addr.arpa
211.127.in-addr.arpa
212.127.in-addr.arpa
213.127.in-addr.arpa
214.127.in-addr.arpa
215.127.in-addr.arpa
216.127.in-addr.arpa
217.127.in-addr.arpa
218.127.in-addr.arpa
219.127.in-addr.arpa
220.127.in-addr.arpa
221.127.in-addr.arpa
222.127.in-addr.arpa
223.127.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
Address01111111.11010000.00000000.00000000127.208.0.0
Subnet mask11111111.11110000.00000000.00000000255.240.0.0
Network01111111.11010000.00000000.00000000127.208.0.0
Broadcast01111111.11011111.11111111.11111111127.223.255.255
Split into smaller subnets/20
/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)

127.208.0.0/12 makes 256 subnets of /20.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1127.208.0.0/20127.208.0.1 to 127.208.15.254127.208.15.2554,094
2127.208.16.0/20127.208.16.1 to 127.208.31.254127.208.31.2554,094
3127.208.32.0/20127.208.32.1 to 127.208.47.254127.208.47.2554,094
4127.208.48.0/20127.208.48.1 to 127.208.63.254127.208.63.2554,094
5127.208.64.0/20127.208.64.1 to 127.208.79.254127.208.79.2554,094
6127.208.80.0/20127.208.80.1 to 127.208.95.254127.208.95.2554,094
7127.208.96.0/20127.208.96.1 to 127.208.111.254127.208.111.2554,094
8127.208.112.0/20127.208.112.1 to 127.208.127.254127.208.127.2554,094
9127.208.128.0/20127.208.128.1 to 127.208.143.254127.208.143.2554,094
10127.208.144.0/20127.208.144.1 to 127.208.159.254127.208.159.2554,094
11127.208.160.0/20127.208.160.1 to 127.208.175.254127.208.175.2554,094
12127.208.176.0/20127.208.176.1 to 127.208.191.254127.208.191.2554,094
13127.208.192.0/20127.208.192.1 to 127.208.207.254127.208.207.2554,094
14127.208.208.0/20127.208.208.1 to 127.208.223.254127.208.223.2554,094
15127.208.224.0/20127.208.224.1 to 127.208.239.254127.208.239.2554,094
16127.208.240.0/20127.208.240.1 to 127.208.255.254127.208.255.2554,094
17127.209.0.0/20127.209.0.1 to 127.209.15.254127.209.15.2554,094
18127.209.16.0/20127.209.16.1 to 127.209.31.254127.209.31.2554,094
19127.209.32.0/20127.209.32.1 to 127.209.47.254127.209.47.2554,094
20127.209.48.0/20127.209.48.1 to 127.209.63.254127.209.63.2554,094
21127.209.64.0/20127.209.64.1 to 127.209.79.254127.209.79.2554,094
22127.209.80.0/20127.209.80.1 to 127.209.95.254127.209.95.2554,094
23127.209.96.0/20127.209.96.1 to 127.209.111.254127.209.111.2554,094
24127.209.112.0/20127.209.112.1 to 127.209.127.254127.209.127.2554,094
25127.209.128.0/20127.209.128.1 to 127.209.143.254127.209.143.2554,094
26127.209.144.0/20127.209.144.1 to 127.209.159.254127.209.159.2554,094
27127.209.160.0/20127.209.160.1 to 127.209.175.254127.209.175.2554,094
28127.209.176.0/20127.209.176.1 to 127.209.191.254127.209.191.2554,094
29127.209.192.0/20127.209.192.1 to 127.209.207.254127.209.207.2554,094
30127.209.208.0/20127.209.208.1 to 127.209.223.254127.209.223.2554,094
31127.209.224.0/20127.209.224.1 to 127.209.239.254127.209.239.2554,094
32127.209.240.0/20127.209.240.1 to 127.209.255.254127.209.255.2554,094
33127.210.0.0/20127.210.0.1 to 127.210.15.254127.210.15.2554,094
34127.210.16.0/20127.210.16.1 to 127.210.31.254127.210.31.2554,094
35127.210.32.0/20127.210.32.1 to 127.210.47.254127.210.47.2554,094
36127.210.48.0/20127.210.48.1 to 127.210.63.254127.210.63.2554,094
37127.210.64.0/20127.210.64.1 to 127.210.79.254127.210.79.2554,094
38127.210.80.0/20127.210.80.1 to 127.210.95.254127.210.95.2554,094
39127.210.96.0/20127.210.96.1 to 127.210.111.254127.210.111.2554,094
40127.210.112.0/20127.210.112.1 to 127.210.127.254127.210.127.2554,094
41127.210.128.0/20127.210.128.1 to 127.210.143.254127.210.143.2554,094
42127.210.144.0/20127.210.144.1 to 127.210.159.254127.210.159.2554,094
43127.210.160.0/20127.210.160.1 to 127.210.175.254127.210.175.2554,094
44127.210.176.0/20127.210.176.1 to 127.210.191.254127.210.191.2554,094
45127.210.192.0/20127.210.192.1 to 127.210.207.254127.210.207.2554,094
46127.210.208.0/20127.210.208.1 to 127.210.223.254127.210.223.2554,094
47127.210.224.0/20127.210.224.1 to 127.210.239.254127.210.239.2554,094
48127.210.240.0/20127.210.240.1 to 127.210.255.254127.210.255.2554,094
49127.211.0.0/20127.211.0.1 to 127.211.15.254127.211.15.2554,094
50127.211.16.0/20127.211.16.1 to 127.211.31.254127.211.31.2554,094
51127.211.32.0/20127.211.32.1 to 127.211.47.254127.211.47.2554,094
52127.211.48.0/20127.211.48.1 to 127.211.63.254127.211.63.2554,094
53127.211.64.0/20127.211.64.1 to 127.211.79.254127.211.79.2554,094
54127.211.80.0/20127.211.80.1 to 127.211.95.254127.211.95.2554,094
55127.211.96.0/20127.211.96.1 to 127.211.111.254127.211.111.2554,094
56127.211.112.0/20127.211.112.1 to 127.211.127.254127.211.127.2554,094
57127.211.128.0/20127.211.128.1 to 127.211.143.254127.211.143.2554,094
58127.211.144.0/20127.211.144.1 to 127.211.159.254127.211.159.2554,094
59127.211.160.0/20127.211.160.1 to 127.211.175.254127.211.175.2554,094
60127.211.176.0/20127.211.176.1 to 127.211.191.254127.211.191.2554,094
61127.211.192.0/20127.211.192.1 to 127.211.207.254127.211.207.2554,094
62127.211.208.0/20127.211.208.1 to 127.211.223.254127.211.223.2554,094
63127.211.224.0/20127.211.224.1 to 127.211.239.254127.211.239.2554,094
64127.211.240.0/20127.211.240.1 to 127.211.255.254127.211.255.2554,094
65127.212.0.0/20127.212.0.1 to 127.212.15.254127.212.15.2554,094
66127.212.16.0/20127.212.16.1 to 127.212.31.254127.212.31.2554,094
67127.212.32.0/20127.212.32.1 to 127.212.47.254127.212.47.2554,094
68127.212.48.0/20127.212.48.1 to 127.212.63.254127.212.63.2554,094
69127.212.64.0/20127.212.64.1 to 127.212.79.254127.212.79.2554,094
70127.212.80.0/20127.212.80.1 to 127.212.95.254127.212.95.2554,094
71127.212.96.0/20127.212.96.1 to 127.212.111.254127.212.111.2554,094
72127.212.112.0/20127.212.112.1 to 127.212.127.254127.212.127.2554,094
73127.212.128.0/20127.212.128.1 to 127.212.143.254127.212.143.2554,094
74127.212.144.0/20127.212.144.1 to 127.212.159.254127.212.159.2554,094
75127.212.160.0/20127.212.160.1 to 127.212.175.254127.212.175.2554,094
76127.212.176.0/20127.212.176.1 to 127.212.191.254127.212.191.2554,094
77127.212.192.0/20127.212.192.1 to 127.212.207.254127.212.207.2554,094
78127.212.208.0/20127.212.208.1 to 127.212.223.254127.212.223.2554,094
79127.212.224.0/20127.212.224.1 to 127.212.239.254127.212.239.2554,094
80127.212.240.0/20127.212.240.1 to 127.212.255.254127.212.255.2554,094
81127.213.0.0/20127.213.0.1 to 127.213.15.254127.213.15.2554,094
82127.213.16.0/20127.213.16.1 to 127.213.31.254127.213.31.2554,094
83127.213.32.0/20127.213.32.1 to 127.213.47.254127.213.47.2554,094
84127.213.48.0/20127.213.48.1 to 127.213.63.254127.213.63.2554,094
85127.213.64.0/20127.213.64.1 to 127.213.79.254127.213.79.2554,094
86127.213.80.0/20127.213.80.1 to 127.213.95.254127.213.95.2554,094
87127.213.96.0/20127.213.96.1 to 127.213.111.254127.213.111.2554,094
88127.213.112.0/20127.213.112.1 to 127.213.127.254127.213.127.2554,094
89127.213.128.0/20127.213.128.1 to 127.213.143.254127.213.143.2554,094
90127.213.144.0/20127.213.144.1 to 127.213.159.254127.213.159.2554,094
91127.213.160.0/20127.213.160.1 to 127.213.175.254127.213.175.2554,094
92127.213.176.0/20127.213.176.1 to 127.213.191.254127.213.191.2554,094
93127.213.192.0/20127.213.192.1 to 127.213.207.254127.213.207.2554,094
94127.213.208.0/20127.213.208.1 to 127.213.223.254127.213.223.2554,094
95127.213.224.0/20127.213.224.1 to 127.213.239.254127.213.239.2554,094
96127.213.240.0/20127.213.240.1 to 127.213.255.254127.213.255.2554,094
97127.214.0.0/20127.214.0.1 to 127.214.15.254127.214.15.2554,094
98127.214.16.0/20127.214.16.1 to 127.214.31.254127.214.31.2554,094
99127.214.32.0/20127.214.32.1 to 127.214.47.254127.214.47.2554,094
100127.214.48.0/20127.214.48.1 to 127.214.63.254127.214.63.2554,094
101127.214.64.0/20127.214.64.1 to 127.214.79.254127.214.79.2554,094
102127.214.80.0/20127.214.80.1 to 127.214.95.254127.214.95.2554,094
103127.214.96.0/20127.214.96.1 to 127.214.111.254127.214.111.2554,094
104127.214.112.0/20127.214.112.1 to 127.214.127.254127.214.127.2554,094
105127.214.128.0/20127.214.128.1 to 127.214.143.254127.214.143.2554,094
106127.214.144.0/20127.214.144.1 to 127.214.159.254127.214.159.2554,094
107127.214.160.0/20127.214.160.1 to 127.214.175.254127.214.175.2554,094
108127.214.176.0/20127.214.176.1 to 127.214.191.254127.214.191.2554,094
109127.214.192.0/20127.214.192.1 to 127.214.207.254127.214.207.2554,094
110127.214.208.0/20127.214.208.1 to 127.214.223.254127.214.223.2554,094
111127.214.224.0/20127.214.224.1 to 127.214.239.254127.214.239.2554,094
112127.214.240.0/20127.214.240.1 to 127.214.255.254127.214.255.2554,094
113127.215.0.0/20127.215.0.1 to 127.215.15.254127.215.15.2554,094
114127.215.16.0/20127.215.16.1 to 127.215.31.254127.215.31.2554,094
115127.215.32.0/20127.215.32.1 to 127.215.47.254127.215.47.2554,094
116127.215.48.0/20127.215.48.1 to 127.215.63.254127.215.63.2554,094
117127.215.64.0/20127.215.64.1 to 127.215.79.254127.215.79.2554,094
118127.215.80.0/20127.215.80.1 to 127.215.95.254127.215.95.2554,094
119127.215.96.0/20127.215.96.1 to 127.215.111.254127.215.111.2554,094
120127.215.112.0/20127.215.112.1 to 127.215.127.254127.215.127.2554,094
121127.215.128.0/20127.215.128.1 to 127.215.143.254127.215.143.2554,094
122127.215.144.0/20127.215.144.1 to 127.215.159.254127.215.159.2554,094
123127.215.160.0/20127.215.160.1 to 127.215.175.254127.215.175.2554,094
124127.215.176.0/20127.215.176.1 to 127.215.191.254127.215.191.2554,094
125127.215.192.0/20127.215.192.1 to 127.215.207.254127.215.207.2554,094
126127.215.208.0/20127.215.208.1 to 127.215.223.254127.215.223.2554,094
127127.215.224.0/20127.215.224.1 to 127.215.239.254127.215.239.2554,094
128127.215.240.0/20127.215.240.1 to 127.215.255.254127.215.255.2554,094
129127.216.0.0/20127.216.0.1 to 127.216.15.254127.216.15.2554,094
130127.216.16.0/20127.216.16.1 to 127.216.31.254127.216.31.2554,094
131127.216.32.0/20127.216.32.1 to 127.216.47.254127.216.47.2554,094
132127.216.48.0/20127.216.48.1 to 127.216.63.254127.216.63.2554,094
133127.216.64.0/20127.216.64.1 to 127.216.79.254127.216.79.2554,094
134127.216.80.0/20127.216.80.1 to 127.216.95.254127.216.95.2554,094
135127.216.96.0/20127.216.96.1 to 127.216.111.254127.216.111.2554,094
136127.216.112.0/20127.216.112.1 to 127.216.127.254127.216.127.2554,094
137127.216.128.0/20127.216.128.1 to 127.216.143.254127.216.143.2554,094
138127.216.144.0/20127.216.144.1 to 127.216.159.254127.216.159.2554,094
139127.216.160.0/20127.216.160.1 to 127.216.175.254127.216.175.2554,094
140127.216.176.0/20127.216.176.1 to 127.216.191.254127.216.191.2554,094
141127.216.192.0/20127.216.192.1 to 127.216.207.254127.216.207.2554,094
142127.216.208.0/20127.216.208.1 to 127.216.223.254127.216.223.2554,094
143127.216.224.0/20127.216.224.1 to 127.216.239.254127.216.239.2554,094
144127.216.240.0/20127.216.240.1 to 127.216.255.254127.216.255.2554,094
145127.217.0.0/20127.217.0.1 to 127.217.15.254127.217.15.2554,094
146127.217.16.0/20127.217.16.1 to 127.217.31.254127.217.31.2554,094
147127.217.32.0/20127.217.32.1 to 127.217.47.254127.217.47.2554,094
148127.217.48.0/20127.217.48.1 to 127.217.63.254127.217.63.2554,094
149127.217.64.0/20127.217.64.1 to 127.217.79.254127.217.79.2554,094
150127.217.80.0/20127.217.80.1 to 127.217.95.254127.217.95.2554,094
151127.217.96.0/20127.217.96.1 to 127.217.111.254127.217.111.2554,094
152127.217.112.0/20127.217.112.1 to 127.217.127.254127.217.127.2554,094
153127.217.128.0/20127.217.128.1 to 127.217.143.254127.217.143.2554,094
154127.217.144.0/20127.217.144.1 to 127.217.159.254127.217.159.2554,094
155127.217.160.0/20127.217.160.1 to 127.217.175.254127.217.175.2554,094
156127.217.176.0/20127.217.176.1 to 127.217.191.254127.217.191.2554,094
157127.217.192.0/20127.217.192.1 to 127.217.207.254127.217.207.2554,094
158127.217.208.0/20127.217.208.1 to 127.217.223.254127.217.223.2554,094
159127.217.224.0/20127.217.224.1 to 127.217.239.254127.217.239.2554,094
160127.217.240.0/20127.217.240.1 to 127.217.255.254127.217.255.2554,094
161127.218.0.0/20127.218.0.1 to 127.218.15.254127.218.15.2554,094
162127.218.16.0/20127.218.16.1 to 127.218.31.254127.218.31.2554,094
163127.218.32.0/20127.218.32.1 to 127.218.47.254127.218.47.2554,094
164127.218.48.0/20127.218.48.1 to 127.218.63.254127.218.63.2554,094
165127.218.64.0/20127.218.64.1 to 127.218.79.254127.218.79.2554,094
166127.218.80.0/20127.218.80.1 to 127.218.95.254127.218.95.2554,094
167127.218.96.0/20127.218.96.1 to 127.218.111.254127.218.111.2554,094
168127.218.112.0/20127.218.112.1 to 127.218.127.254127.218.127.2554,094
169127.218.128.0/20127.218.128.1 to 127.218.143.254127.218.143.2554,094
170127.218.144.0/20127.218.144.1 to 127.218.159.254127.218.159.2554,094
171127.218.160.0/20127.218.160.1 to 127.218.175.254127.218.175.2554,094
172127.218.176.0/20127.218.176.1 to 127.218.191.254127.218.191.2554,094
173127.218.192.0/20127.218.192.1 to 127.218.207.254127.218.207.2554,094
174127.218.208.0/20127.218.208.1 to 127.218.223.254127.218.223.2554,094
175127.218.224.0/20127.218.224.1 to 127.218.239.254127.218.239.2554,094
176127.218.240.0/20127.218.240.1 to 127.218.255.254127.218.255.2554,094
177127.219.0.0/20127.219.0.1 to 127.219.15.254127.219.15.2554,094
178127.219.16.0/20127.219.16.1 to 127.219.31.254127.219.31.2554,094
179127.219.32.0/20127.219.32.1 to 127.219.47.254127.219.47.2554,094
180127.219.48.0/20127.219.48.1 to 127.219.63.254127.219.63.2554,094
181127.219.64.0/20127.219.64.1 to 127.219.79.254127.219.79.2554,094
182127.219.80.0/20127.219.80.1 to 127.219.95.254127.219.95.2554,094
183127.219.96.0/20127.219.96.1 to 127.219.111.254127.219.111.2554,094
184127.219.112.0/20127.219.112.1 to 127.219.127.254127.219.127.2554,094
185127.219.128.0/20127.219.128.1 to 127.219.143.254127.219.143.2554,094
186127.219.144.0/20127.219.144.1 to 127.219.159.254127.219.159.2554,094
187127.219.160.0/20127.219.160.1 to 127.219.175.254127.219.175.2554,094
188127.219.176.0/20127.219.176.1 to 127.219.191.254127.219.191.2554,094
189127.219.192.0/20127.219.192.1 to 127.219.207.254127.219.207.2554,094
190127.219.208.0/20127.219.208.1 to 127.219.223.254127.219.223.2554,094
191127.219.224.0/20127.219.224.1 to 127.219.239.254127.219.239.2554,094
192127.219.240.0/20127.219.240.1 to 127.219.255.254127.219.255.2554,094
193127.220.0.0/20127.220.0.1 to 127.220.15.254127.220.15.2554,094
194127.220.16.0/20127.220.16.1 to 127.220.31.254127.220.31.2554,094
195127.220.32.0/20127.220.32.1 to 127.220.47.254127.220.47.2554,094
196127.220.48.0/20127.220.48.1 to 127.220.63.254127.220.63.2554,094
197127.220.64.0/20127.220.64.1 to 127.220.79.254127.220.79.2554,094
198127.220.80.0/20127.220.80.1 to 127.220.95.254127.220.95.2554,094
199127.220.96.0/20127.220.96.1 to 127.220.111.254127.220.111.2554,094
200127.220.112.0/20127.220.112.1 to 127.220.127.254127.220.127.2554,094
201127.220.128.0/20127.220.128.1 to 127.220.143.254127.220.143.2554,094
202127.220.144.0/20127.220.144.1 to 127.220.159.254127.220.159.2554,094
203127.220.160.0/20127.220.160.1 to 127.220.175.254127.220.175.2554,094
204127.220.176.0/20127.220.176.1 to 127.220.191.254127.220.191.2554,094
205127.220.192.0/20127.220.192.1 to 127.220.207.254127.220.207.2554,094
206127.220.208.0/20127.220.208.1 to 127.220.223.254127.220.223.2554,094
207127.220.224.0/20127.220.224.1 to 127.220.239.254127.220.239.2554,094
208127.220.240.0/20127.220.240.1 to 127.220.255.254127.220.255.2554,094
209127.221.0.0/20127.221.0.1 to 127.221.15.254127.221.15.2554,094
210127.221.16.0/20127.221.16.1 to 127.221.31.254127.221.31.2554,094
211127.221.32.0/20127.221.32.1 to 127.221.47.254127.221.47.2554,094
212127.221.48.0/20127.221.48.1 to 127.221.63.254127.221.63.2554,094
213127.221.64.0/20127.221.64.1 to 127.221.79.254127.221.79.2554,094
214127.221.80.0/20127.221.80.1 to 127.221.95.254127.221.95.2554,094
215127.221.96.0/20127.221.96.1 to 127.221.111.254127.221.111.2554,094
216127.221.112.0/20127.221.112.1 to 127.221.127.254127.221.127.2554,094
217127.221.128.0/20127.221.128.1 to 127.221.143.254127.221.143.2554,094
218127.221.144.0/20127.221.144.1 to 127.221.159.254127.221.159.2554,094
219127.221.160.0/20127.221.160.1 to 127.221.175.254127.221.175.2554,094
220127.221.176.0/20127.221.176.1 to 127.221.191.254127.221.191.2554,094
221127.221.192.0/20127.221.192.1 to 127.221.207.254127.221.207.2554,094
222127.221.208.0/20127.221.208.1 to 127.221.223.254127.221.223.2554,094
223127.221.224.0/20127.221.224.1 to 127.221.239.254127.221.239.2554,094
224127.221.240.0/20127.221.240.1 to 127.221.255.254127.221.255.2554,094
225127.222.0.0/20127.222.0.1 to 127.222.15.254127.222.15.2554,094
226127.222.16.0/20127.222.16.1 to 127.222.31.254127.222.31.2554,094
227127.222.32.0/20127.222.32.1 to 127.222.47.254127.222.47.2554,094
228127.222.48.0/20127.222.48.1 to 127.222.63.254127.222.63.2554,094
229127.222.64.0/20127.222.64.1 to 127.222.79.254127.222.79.2554,094
230127.222.80.0/20127.222.80.1 to 127.222.95.254127.222.95.2554,094
231127.222.96.0/20127.222.96.1 to 127.222.111.254127.222.111.2554,094
232127.222.112.0/20127.222.112.1 to 127.222.127.254127.222.127.2554,094
233127.222.128.0/20127.222.128.1 to 127.222.143.254127.222.143.2554,094
234127.222.144.0/20127.222.144.1 to 127.222.159.254127.222.159.2554,094
235127.222.160.0/20127.222.160.1 to 127.222.175.254127.222.175.2554,094
236127.222.176.0/20127.222.176.1 to 127.222.191.254127.222.191.2554,094
237127.222.192.0/20127.222.192.1 to 127.222.207.254127.222.207.2554,094
238127.222.208.0/20127.222.208.1 to 127.222.223.254127.222.223.2554,094
239127.222.224.0/20127.222.224.1 to 127.222.239.254127.222.239.2554,094
240127.222.240.0/20127.222.240.1 to 127.222.255.254127.222.255.2554,094
241127.223.0.0/20127.223.0.1 to 127.223.15.254127.223.15.2554,094
242127.223.16.0/20127.223.16.1 to 127.223.31.254127.223.31.2554,094
243127.223.32.0/20127.223.32.1 to 127.223.47.254127.223.47.2554,094
244127.223.48.0/20127.223.48.1 to 127.223.63.254127.223.63.2554,094
245127.223.64.0/20127.223.64.1 to 127.223.79.254127.223.79.2554,094
246127.223.80.0/20127.223.80.1 to 127.223.95.254127.223.95.2554,094
247127.223.96.0/20127.223.96.1 to 127.223.111.254127.223.111.2554,094
248127.223.112.0/20127.223.112.1 to 127.223.127.254127.223.127.2554,094
249127.223.128.0/20127.223.128.1 to 127.223.143.254127.223.143.2554,094
250127.223.144.0/20127.223.144.1 to 127.223.159.254127.223.159.2554,094
251127.223.160.0/20127.223.160.1 to 127.223.175.254127.223.175.2554,094
252127.223.176.0/20127.223.176.1 to 127.223.191.254127.223.191.2554,094
253127.223.192.0/20127.223.192.1 to 127.223.207.254127.223.207.2554,094
254127.223.208.0/20127.223.208.1 to 127.223.223.254127.223.223.2554,094
255127.223.224.0/20127.223.224.1 to 127.223.239.254127.223.239.2554,094
256127.223.240.0/20127.223.240.1 to 127.223.255.254127.223.255.2554,094

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.