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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.

Network128.0.0.0/4
Usable hosts268,435,454
Subnet mask240.0.0.0
Addresses268,435,456
Network address
128.0.0.0
Broadcast address
143.255.255.255
First usable
128.0.0.1
Last usable
143.255.255.254
Usable hosts
268,435,454 (268,435,456 less the network and broadcast addresses)
Subnet mask
240.0.0.0
Wildcard mask
15.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/4
Type
Public public
Old class
B (default /16)
As numbers
Hex 80000000 · Integer 2147483648 to 2415919103
Reverse DNS zones
128.in-addr.arpa
129.in-addr.arpa
130.in-addr.arpa
131.in-addr.arpa
132.in-addr.arpa
133.in-addr.arpa
134.in-addr.arpa
135.in-addr.arpa
136.in-addr.arpa
137.in-addr.arpa
138.in-addr.arpa
139.in-addr.arpa
140.in-addr.arpa
141.in-addr.arpa
142.in-addr.arpa
143.in-addr.arpa
/4 is not on a 8-bit boundary, so it takes 16 /8 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10000000.00000000.00000000.00000000128.0.0.0
Subnet mask11110000.00000000.00000000.00000000240.0.0.0
Network10000000.00000000.00000000.00000000128.0.0.0
Broadcast10001111.11111111.11111111.11111111143.255.255.255
Split into smaller subnets/12
/5 (2)/6 (4)/7 (8)/8 (16)/9 (32)/10 (64)/11 (128)/12 (256)/13 (512)/14 (1,024)/15 (2,048)/16 (4,096)

128.0.0.0/4 makes 256 subnets of /12.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1128.0.0.0/12128.0.0.1 to 128.15.255.254128.15.255.2551,048,574
2128.16.0.0/12128.16.0.1 to 128.31.255.254128.31.255.2551,048,574
3128.32.0.0/12128.32.0.1 to 128.47.255.254128.47.255.2551,048,574
4128.48.0.0/12128.48.0.1 to 128.63.255.254128.63.255.2551,048,574
5128.64.0.0/12128.64.0.1 to 128.79.255.254128.79.255.2551,048,574
6128.80.0.0/12128.80.0.1 to 128.95.255.254128.95.255.2551,048,574
7128.96.0.0/12128.96.0.1 to 128.111.255.254128.111.255.2551,048,574
8128.112.0.0/12128.112.0.1 to 128.127.255.254128.127.255.2551,048,574
9128.128.0.0/12128.128.0.1 to 128.143.255.254128.143.255.2551,048,574
10128.144.0.0/12128.144.0.1 to 128.159.255.254128.159.255.2551,048,574
11128.160.0.0/12128.160.0.1 to 128.175.255.254128.175.255.2551,048,574
12128.176.0.0/12128.176.0.1 to 128.191.255.254128.191.255.2551,048,574
13128.192.0.0/12128.192.0.1 to 128.207.255.254128.207.255.2551,048,574
14128.208.0.0/12128.208.0.1 to 128.223.255.254128.223.255.2551,048,574
15128.224.0.0/12128.224.0.1 to 128.239.255.254128.239.255.2551,048,574
16128.240.0.0/12128.240.0.1 to 128.255.255.254128.255.255.2551,048,574
17129.0.0.0/12129.0.0.1 to 129.15.255.254129.15.255.2551,048,574
18129.16.0.0/12129.16.0.1 to 129.31.255.254129.31.255.2551,048,574
19129.32.0.0/12129.32.0.1 to 129.47.255.254129.47.255.2551,048,574
20129.48.0.0/12129.48.0.1 to 129.63.255.254129.63.255.2551,048,574
21129.64.0.0/12129.64.0.1 to 129.79.255.254129.79.255.2551,048,574
22129.80.0.0/12129.80.0.1 to 129.95.255.254129.95.255.2551,048,574
23129.96.0.0/12129.96.0.1 to 129.111.255.254129.111.255.2551,048,574
24129.112.0.0/12129.112.0.1 to 129.127.255.254129.127.255.2551,048,574
25129.128.0.0/12129.128.0.1 to 129.143.255.254129.143.255.2551,048,574
26129.144.0.0/12129.144.0.1 to 129.159.255.254129.159.255.2551,048,574
27129.160.0.0/12129.160.0.1 to 129.175.255.254129.175.255.2551,048,574
28129.176.0.0/12129.176.0.1 to 129.191.255.254129.191.255.2551,048,574
29129.192.0.0/12129.192.0.1 to 129.207.255.254129.207.255.2551,048,574
30129.208.0.0/12129.208.0.1 to 129.223.255.254129.223.255.2551,048,574
31129.224.0.0/12129.224.0.1 to 129.239.255.254129.239.255.2551,048,574
32129.240.0.0/12129.240.0.1 to 129.255.255.254129.255.255.2551,048,574
33130.0.0.0/12130.0.0.1 to 130.15.255.254130.15.255.2551,048,574
34130.16.0.0/12130.16.0.1 to 130.31.255.254130.31.255.2551,048,574
35130.32.0.0/12130.32.0.1 to 130.47.255.254130.47.255.2551,048,574
36130.48.0.0/12130.48.0.1 to 130.63.255.254130.63.255.2551,048,574
37130.64.0.0/12130.64.0.1 to 130.79.255.254130.79.255.2551,048,574
38130.80.0.0/12130.80.0.1 to 130.95.255.254130.95.255.2551,048,574
39130.96.0.0/12130.96.0.1 to 130.111.255.254130.111.255.2551,048,574
40130.112.0.0/12130.112.0.1 to 130.127.255.254130.127.255.2551,048,574
41130.128.0.0/12130.128.0.1 to 130.143.255.254130.143.255.2551,048,574
42130.144.0.0/12130.144.0.1 to 130.159.255.254130.159.255.2551,048,574
43130.160.0.0/12130.160.0.1 to 130.175.255.254130.175.255.2551,048,574
44130.176.0.0/12130.176.0.1 to 130.191.255.254130.191.255.2551,048,574
45130.192.0.0/12130.192.0.1 to 130.207.255.254130.207.255.2551,048,574
46130.208.0.0/12130.208.0.1 to 130.223.255.254130.223.255.2551,048,574
47130.224.0.0/12130.224.0.1 to 130.239.255.254130.239.255.2551,048,574
48130.240.0.0/12130.240.0.1 to 130.255.255.254130.255.255.2551,048,574
49131.0.0.0/12131.0.0.1 to 131.15.255.254131.15.255.2551,048,574
50131.16.0.0/12131.16.0.1 to 131.31.255.254131.31.255.2551,048,574
51131.32.0.0/12131.32.0.1 to 131.47.255.254131.47.255.2551,048,574
52131.48.0.0/12131.48.0.1 to 131.63.255.254131.63.255.2551,048,574
53131.64.0.0/12131.64.0.1 to 131.79.255.254131.79.255.2551,048,574
54131.80.0.0/12131.80.0.1 to 131.95.255.254131.95.255.2551,048,574
55131.96.0.0/12131.96.0.1 to 131.111.255.254131.111.255.2551,048,574
56131.112.0.0/12131.112.0.1 to 131.127.255.254131.127.255.2551,048,574
57131.128.0.0/12131.128.0.1 to 131.143.255.254131.143.255.2551,048,574
58131.144.0.0/12131.144.0.1 to 131.159.255.254131.159.255.2551,048,574
59131.160.0.0/12131.160.0.1 to 131.175.255.254131.175.255.2551,048,574
60131.176.0.0/12131.176.0.1 to 131.191.255.254131.191.255.2551,048,574
61131.192.0.0/12131.192.0.1 to 131.207.255.254131.207.255.2551,048,574
62131.208.0.0/12131.208.0.1 to 131.223.255.254131.223.255.2551,048,574
63131.224.0.0/12131.224.0.1 to 131.239.255.254131.239.255.2551,048,574
64131.240.0.0/12131.240.0.1 to 131.255.255.254131.255.255.2551,048,574
65132.0.0.0/12132.0.0.1 to 132.15.255.254132.15.255.2551,048,574
66132.16.0.0/12132.16.0.1 to 132.31.255.254132.31.255.2551,048,574
67132.32.0.0/12132.32.0.1 to 132.47.255.254132.47.255.2551,048,574
68132.48.0.0/12132.48.0.1 to 132.63.255.254132.63.255.2551,048,574
69132.64.0.0/12132.64.0.1 to 132.79.255.254132.79.255.2551,048,574
70132.80.0.0/12132.80.0.1 to 132.95.255.254132.95.255.2551,048,574
71132.96.0.0/12132.96.0.1 to 132.111.255.254132.111.255.2551,048,574
72132.112.0.0/12132.112.0.1 to 132.127.255.254132.127.255.2551,048,574
73132.128.0.0/12132.128.0.1 to 132.143.255.254132.143.255.2551,048,574
74132.144.0.0/12132.144.0.1 to 132.159.255.254132.159.255.2551,048,574
75132.160.0.0/12132.160.0.1 to 132.175.255.254132.175.255.2551,048,574
76132.176.0.0/12132.176.0.1 to 132.191.255.254132.191.255.2551,048,574
77132.192.0.0/12132.192.0.1 to 132.207.255.254132.207.255.2551,048,574
78132.208.0.0/12132.208.0.1 to 132.223.255.254132.223.255.2551,048,574
79132.224.0.0/12132.224.0.1 to 132.239.255.254132.239.255.2551,048,574
80132.240.0.0/12132.240.0.1 to 132.255.255.254132.255.255.2551,048,574
81133.0.0.0/12133.0.0.1 to 133.15.255.254133.15.255.2551,048,574
82133.16.0.0/12133.16.0.1 to 133.31.255.254133.31.255.2551,048,574
83133.32.0.0/12133.32.0.1 to 133.47.255.254133.47.255.2551,048,574
84133.48.0.0/12133.48.0.1 to 133.63.255.254133.63.255.2551,048,574
85133.64.0.0/12133.64.0.1 to 133.79.255.254133.79.255.2551,048,574
86133.80.0.0/12133.80.0.1 to 133.95.255.254133.95.255.2551,048,574
87133.96.0.0/12133.96.0.1 to 133.111.255.254133.111.255.2551,048,574
88133.112.0.0/12133.112.0.1 to 133.127.255.254133.127.255.2551,048,574
89133.128.0.0/12133.128.0.1 to 133.143.255.254133.143.255.2551,048,574
90133.144.0.0/12133.144.0.1 to 133.159.255.254133.159.255.2551,048,574
91133.160.0.0/12133.160.0.1 to 133.175.255.254133.175.255.2551,048,574
92133.176.0.0/12133.176.0.1 to 133.191.255.254133.191.255.2551,048,574
93133.192.0.0/12133.192.0.1 to 133.207.255.254133.207.255.2551,048,574
94133.208.0.0/12133.208.0.1 to 133.223.255.254133.223.255.2551,048,574
95133.224.0.0/12133.224.0.1 to 133.239.255.254133.239.255.2551,048,574
96133.240.0.0/12133.240.0.1 to 133.255.255.254133.255.255.2551,048,574
97134.0.0.0/12134.0.0.1 to 134.15.255.254134.15.255.2551,048,574
98134.16.0.0/12134.16.0.1 to 134.31.255.254134.31.255.2551,048,574
99134.32.0.0/12134.32.0.1 to 134.47.255.254134.47.255.2551,048,574
100134.48.0.0/12134.48.0.1 to 134.63.255.254134.63.255.2551,048,574
101134.64.0.0/12134.64.0.1 to 134.79.255.254134.79.255.2551,048,574
102134.80.0.0/12134.80.0.1 to 134.95.255.254134.95.255.2551,048,574
103134.96.0.0/12134.96.0.1 to 134.111.255.254134.111.255.2551,048,574
104134.112.0.0/12134.112.0.1 to 134.127.255.254134.127.255.2551,048,574
105134.128.0.0/12134.128.0.1 to 134.143.255.254134.143.255.2551,048,574
106134.144.0.0/12134.144.0.1 to 134.159.255.254134.159.255.2551,048,574
107134.160.0.0/12134.160.0.1 to 134.175.255.254134.175.255.2551,048,574
108134.176.0.0/12134.176.0.1 to 134.191.255.254134.191.255.2551,048,574
109134.192.0.0/12134.192.0.1 to 134.207.255.254134.207.255.2551,048,574
110134.208.0.0/12134.208.0.1 to 134.223.255.254134.223.255.2551,048,574
111134.224.0.0/12134.224.0.1 to 134.239.255.254134.239.255.2551,048,574
112134.240.0.0/12134.240.0.1 to 134.255.255.254134.255.255.2551,048,574
113135.0.0.0/12135.0.0.1 to 135.15.255.254135.15.255.2551,048,574
114135.16.0.0/12135.16.0.1 to 135.31.255.254135.31.255.2551,048,574
115135.32.0.0/12135.32.0.1 to 135.47.255.254135.47.255.2551,048,574
116135.48.0.0/12135.48.0.1 to 135.63.255.254135.63.255.2551,048,574
117135.64.0.0/12135.64.0.1 to 135.79.255.254135.79.255.2551,048,574
118135.80.0.0/12135.80.0.1 to 135.95.255.254135.95.255.2551,048,574
119135.96.0.0/12135.96.0.1 to 135.111.255.254135.111.255.2551,048,574
120135.112.0.0/12135.112.0.1 to 135.127.255.254135.127.255.2551,048,574
121135.128.0.0/12135.128.0.1 to 135.143.255.254135.143.255.2551,048,574
122135.144.0.0/12135.144.0.1 to 135.159.255.254135.159.255.2551,048,574
123135.160.0.0/12135.160.0.1 to 135.175.255.254135.175.255.2551,048,574
124135.176.0.0/12135.176.0.1 to 135.191.255.254135.191.255.2551,048,574
125135.192.0.0/12135.192.0.1 to 135.207.255.254135.207.255.2551,048,574
126135.208.0.0/12135.208.0.1 to 135.223.255.254135.223.255.2551,048,574
127135.224.0.0/12135.224.0.1 to 135.239.255.254135.239.255.2551,048,574
128135.240.0.0/12135.240.0.1 to 135.255.255.254135.255.255.2551,048,574
129136.0.0.0/12136.0.0.1 to 136.15.255.254136.15.255.2551,048,574
130136.16.0.0/12136.16.0.1 to 136.31.255.254136.31.255.2551,048,574
131136.32.0.0/12136.32.0.1 to 136.47.255.254136.47.255.2551,048,574
132136.48.0.0/12136.48.0.1 to 136.63.255.254136.63.255.2551,048,574
133136.64.0.0/12136.64.0.1 to 136.79.255.254136.79.255.2551,048,574
134136.80.0.0/12136.80.0.1 to 136.95.255.254136.95.255.2551,048,574
135136.96.0.0/12136.96.0.1 to 136.111.255.254136.111.255.2551,048,574
136136.112.0.0/12136.112.0.1 to 136.127.255.254136.127.255.2551,048,574
137136.128.0.0/12136.128.0.1 to 136.143.255.254136.143.255.2551,048,574
138136.144.0.0/12136.144.0.1 to 136.159.255.254136.159.255.2551,048,574
139136.160.0.0/12136.160.0.1 to 136.175.255.254136.175.255.2551,048,574
140136.176.0.0/12136.176.0.1 to 136.191.255.254136.191.255.2551,048,574
141136.192.0.0/12136.192.0.1 to 136.207.255.254136.207.255.2551,048,574
142136.208.0.0/12136.208.0.1 to 136.223.255.254136.223.255.2551,048,574
143136.224.0.0/12136.224.0.1 to 136.239.255.254136.239.255.2551,048,574
144136.240.0.0/12136.240.0.1 to 136.255.255.254136.255.255.2551,048,574
145137.0.0.0/12137.0.0.1 to 137.15.255.254137.15.255.2551,048,574
146137.16.0.0/12137.16.0.1 to 137.31.255.254137.31.255.2551,048,574
147137.32.0.0/12137.32.0.1 to 137.47.255.254137.47.255.2551,048,574
148137.48.0.0/12137.48.0.1 to 137.63.255.254137.63.255.2551,048,574
149137.64.0.0/12137.64.0.1 to 137.79.255.254137.79.255.2551,048,574
150137.80.0.0/12137.80.0.1 to 137.95.255.254137.95.255.2551,048,574
151137.96.0.0/12137.96.0.1 to 137.111.255.254137.111.255.2551,048,574
152137.112.0.0/12137.112.0.1 to 137.127.255.254137.127.255.2551,048,574
153137.128.0.0/12137.128.0.1 to 137.143.255.254137.143.255.2551,048,574
154137.144.0.0/12137.144.0.1 to 137.159.255.254137.159.255.2551,048,574
155137.160.0.0/12137.160.0.1 to 137.175.255.254137.175.255.2551,048,574
156137.176.0.0/12137.176.0.1 to 137.191.255.254137.191.255.2551,048,574
157137.192.0.0/12137.192.0.1 to 137.207.255.254137.207.255.2551,048,574
158137.208.0.0/12137.208.0.1 to 137.223.255.254137.223.255.2551,048,574
159137.224.0.0/12137.224.0.1 to 137.239.255.254137.239.255.2551,048,574
160137.240.0.0/12137.240.0.1 to 137.255.255.254137.255.255.2551,048,574
161138.0.0.0/12138.0.0.1 to 138.15.255.254138.15.255.2551,048,574
162138.16.0.0/12138.16.0.1 to 138.31.255.254138.31.255.2551,048,574
163138.32.0.0/12138.32.0.1 to 138.47.255.254138.47.255.2551,048,574
164138.48.0.0/12138.48.0.1 to 138.63.255.254138.63.255.2551,048,574
165138.64.0.0/12138.64.0.1 to 138.79.255.254138.79.255.2551,048,574
166138.80.0.0/12138.80.0.1 to 138.95.255.254138.95.255.2551,048,574
167138.96.0.0/12138.96.0.1 to 138.111.255.254138.111.255.2551,048,574
168138.112.0.0/12138.112.0.1 to 138.127.255.254138.127.255.2551,048,574
169138.128.0.0/12138.128.0.1 to 138.143.255.254138.143.255.2551,048,574
170138.144.0.0/12138.144.0.1 to 138.159.255.254138.159.255.2551,048,574
171138.160.0.0/12138.160.0.1 to 138.175.255.254138.175.255.2551,048,574
172138.176.0.0/12138.176.0.1 to 138.191.255.254138.191.255.2551,048,574
173138.192.0.0/12138.192.0.1 to 138.207.255.254138.207.255.2551,048,574
174138.208.0.0/12138.208.0.1 to 138.223.255.254138.223.255.2551,048,574
175138.224.0.0/12138.224.0.1 to 138.239.255.254138.239.255.2551,048,574
176138.240.0.0/12138.240.0.1 to 138.255.255.254138.255.255.2551,048,574
177139.0.0.0/12139.0.0.1 to 139.15.255.254139.15.255.2551,048,574
178139.16.0.0/12139.16.0.1 to 139.31.255.254139.31.255.2551,048,574
179139.32.0.0/12139.32.0.1 to 139.47.255.254139.47.255.2551,048,574
180139.48.0.0/12139.48.0.1 to 139.63.255.254139.63.255.2551,048,574
181139.64.0.0/12139.64.0.1 to 139.79.255.254139.79.255.2551,048,574
182139.80.0.0/12139.80.0.1 to 139.95.255.254139.95.255.2551,048,574
183139.96.0.0/12139.96.0.1 to 139.111.255.254139.111.255.2551,048,574
184139.112.0.0/12139.112.0.1 to 139.127.255.254139.127.255.2551,048,574
185139.128.0.0/12139.128.0.1 to 139.143.255.254139.143.255.2551,048,574
186139.144.0.0/12139.144.0.1 to 139.159.255.254139.159.255.2551,048,574
187139.160.0.0/12139.160.0.1 to 139.175.255.254139.175.255.2551,048,574
188139.176.0.0/12139.176.0.1 to 139.191.255.254139.191.255.2551,048,574
189139.192.0.0/12139.192.0.1 to 139.207.255.254139.207.255.2551,048,574
190139.208.0.0/12139.208.0.1 to 139.223.255.254139.223.255.2551,048,574
191139.224.0.0/12139.224.0.1 to 139.239.255.254139.239.255.2551,048,574
192139.240.0.0/12139.240.0.1 to 139.255.255.254139.255.255.2551,048,574
193140.0.0.0/12140.0.0.1 to 140.15.255.254140.15.255.2551,048,574
194140.16.0.0/12140.16.0.1 to 140.31.255.254140.31.255.2551,048,574
195140.32.0.0/12140.32.0.1 to 140.47.255.254140.47.255.2551,048,574
196140.48.0.0/12140.48.0.1 to 140.63.255.254140.63.255.2551,048,574
197140.64.0.0/12140.64.0.1 to 140.79.255.254140.79.255.2551,048,574
198140.80.0.0/12140.80.0.1 to 140.95.255.254140.95.255.2551,048,574
199140.96.0.0/12140.96.0.1 to 140.111.255.254140.111.255.2551,048,574
200140.112.0.0/12140.112.0.1 to 140.127.255.254140.127.255.2551,048,574
201140.128.0.0/12140.128.0.1 to 140.143.255.254140.143.255.2551,048,574
202140.144.0.0/12140.144.0.1 to 140.159.255.254140.159.255.2551,048,574
203140.160.0.0/12140.160.0.1 to 140.175.255.254140.175.255.2551,048,574
204140.176.0.0/12140.176.0.1 to 140.191.255.254140.191.255.2551,048,574
205140.192.0.0/12140.192.0.1 to 140.207.255.254140.207.255.2551,048,574
206140.208.0.0/12140.208.0.1 to 140.223.255.254140.223.255.2551,048,574
207140.224.0.0/12140.224.0.1 to 140.239.255.254140.239.255.2551,048,574
208140.240.0.0/12140.240.0.1 to 140.255.255.254140.255.255.2551,048,574
209141.0.0.0/12141.0.0.1 to 141.15.255.254141.15.255.2551,048,574
210141.16.0.0/12141.16.0.1 to 141.31.255.254141.31.255.2551,048,574
211141.32.0.0/12141.32.0.1 to 141.47.255.254141.47.255.2551,048,574
212141.48.0.0/12141.48.0.1 to 141.63.255.254141.63.255.2551,048,574
213141.64.0.0/12141.64.0.1 to 141.79.255.254141.79.255.2551,048,574
214141.80.0.0/12141.80.0.1 to 141.95.255.254141.95.255.2551,048,574
215141.96.0.0/12141.96.0.1 to 141.111.255.254141.111.255.2551,048,574
216141.112.0.0/12141.112.0.1 to 141.127.255.254141.127.255.2551,048,574
217141.128.0.0/12141.128.0.1 to 141.143.255.254141.143.255.2551,048,574
218141.144.0.0/12141.144.0.1 to 141.159.255.254141.159.255.2551,048,574
219141.160.0.0/12141.160.0.1 to 141.175.255.254141.175.255.2551,048,574
220141.176.0.0/12141.176.0.1 to 141.191.255.254141.191.255.2551,048,574
221141.192.0.0/12141.192.0.1 to 141.207.255.254141.207.255.2551,048,574
222141.208.0.0/12141.208.0.1 to 141.223.255.254141.223.255.2551,048,574
223141.224.0.0/12141.224.0.1 to 141.239.255.254141.239.255.2551,048,574
224141.240.0.0/12141.240.0.1 to 141.255.255.254141.255.255.2551,048,574
225142.0.0.0/12142.0.0.1 to 142.15.255.254142.15.255.2551,048,574
226142.16.0.0/12142.16.0.1 to 142.31.255.254142.31.255.2551,048,574
227142.32.0.0/12142.32.0.1 to 142.47.255.254142.47.255.2551,048,574
228142.48.0.0/12142.48.0.1 to 142.63.255.254142.63.255.2551,048,574
229142.64.0.0/12142.64.0.1 to 142.79.255.254142.79.255.2551,048,574
230142.80.0.0/12142.80.0.1 to 142.95.255.254142.95.255.2551,048,574
231142.96.0.0/12142.96.0.1 to 142.111.255.254142.111.255.2551,048,574
232142.112.0.0/12142.112.0.1 to 142.127.255.254142.127.255.2551,048,574
233142.128.0.0/12142.128.0.1 to 142.143.255.254142.143.255.2551,048,574
234142.144.0.0/12142.144.0.1 to 142.159.255.254142.159.255.2551,048,574
235142.160.0.0/12142.160.0.1 to 142.175.255.254142.175.255.2551,048,574
236142.176.0.0/12142.176.0.1 to 142.191.255.254142.191.255.2551,048,574
237142.192.0.0/12142.192.0.1 to 142.207.255.254142.207.255.2551,048,574
238142.208.0.0/12142.208.0.1 to 142.223.255.254142.223.255.2551,048,574
239142.224.0.0/12142.224.0.1 to 142.239.255.254142.239.255.2551,048,574
240142.240.0.0/12142.240.0.1 to 142.255.255.254142.255.255.2551,048,574
241143.0.0.0/12143.0.0.1 to 143.15.255.254143.15.255.2551,048,574
242143.16.0.0/12143.16.0.1 to 143.31.255.254143.31.255.2551,048,574
243143.32.0.0/12143.32.0.1 to 143.47.255.254143.47.255.2551,048,574
244143.48.0.0/12143.48.0.1 to 143.63.255.254143.63.255.2551,048,574
245143.64.0.0/12143.64.0.1 to 143.79.255.254143.79.255.2551,048,574
246143.80.0.0/12143.80.0.1 to 143.95.255.254143.95.255.2551,048,574
247143.96.0.0/12143.96.0.1 to 143.111.255.254143.111.255.2551,048,574
248143.112.0.0/12143.112.0.1 to 143.127.255.254143.127.255.2551,048,574
249143.128.0.0/12143.128.0.1 to 143.143.255.254143.143.255.2551,048,574
250143.144.0.0/12143.144.0.1 to 143.159.255.254143.159.255.2551,048,574
251143.160.0.0/12143.160.0.1 to 143.175.255.254143.175.255.2551,048,574
252143.176.0.0/12143.176.0.1 to 143.191.255.254143.191.255.2551,048,574
253143.192.0.0/12143.192.0.1 to 143.207.255.254143.207.255.2551,048,574
254143.208.0.0/12143.208.0.1 to 143.223.255.254143.223.255.2551,048,574
255143.224.0.0/12143.224.0.1 to 143.239.255.254143.239.255.2551,048,574
256143.240.0.0/12143.240.0.1 to 143.255.255.254143.255.255.2551,048,574

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.