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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.

Network127.128.0.0/10
Usable hosts4,194,302
Subnet mask255.192.0.0
Addresses4,194,304
Network address
127.128.0.0
Broadcast address
127.191.255.255
First usable
127.128.0.1
Last usable
127.191.255.254
Usable hosts
4,194,302 (4,194,304 less the network and broadcast addresses)
Subnet mask
255.192.0.0
Wildcard mask
0.63.255.255 (Cisco ACLs, OSPF)
Prefix length
/10
Type
Loopback 127.0.0.0/8
This computer
Old class
A (default /8)
As numbers
Hex 7F800000 · Integer 2139095040 to 2143289343
Reverse DNS zones
128.127.in-addr.arpa
129.127.in-addr.arpa
130.127.in-addr.arpa
131.127.in-addr.arpa
132.127.in-addr.arpa
133.127.in-addr.arpa
134.127.in-addr.arpa
135.127.in-addr.arpa
136.127.in-addr.arpa
137.127.in-addr.arpa
138.127.in-addr.arpa
139.127.in-addr.arpa
140.127.in-addr.arpa
141.127.in-addr.arpa
142.127.in-addr.arpa
143.127.in-addr.arpa
and 48 more
/10 is not on a 8-bit boundary, so it takes 64 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01111111.10000000.00000000.00000000127.128.0.0
Subnet mask11111111.11000000.00000000.00000000255.192.0.0
Network01111111.10000000.00000000.00000000127.128.0.0
Broadcast01111111.10111111.11111111.11111111127.191.255.255
Split into smaller subnets/19
/11 (2)/12 (4)/13 (8)/14 (16)/15 (32)/16 (64)/17 (128)/18 (256)/19 (512)/20 (1,024)/21 (2,048)/22 (4,096)

127.128.0.0/10 makes 512 subnets of /19; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1127.128.0.0/19127.128.0.1 to 127.128.31.254127.128.31.2558,190
2127.128.32.0/19127.128.32.1 to 127.128.63.254127.128.63.2558,190
3127.128.64.0/19127.128.64.1 to 127.128.95.254127.128.95.2558,190
4127.128.96.0/19127.128.96.1 to 127.128.127.254127.128.127.2558,190
5127.128.128.0/19127.128.128.1 to 127.128.159.254127.128.159.2558,190
6127.128.160.0/19127.128.160.1 to 127.128.191.254127.128.191.2558,190
7127.128.192.0/19127.128.192.1 to 127.128.223.254127.128.223.2558,190
8127.128.224.0/19127.128.224.1 to 127.128.255.254127.128.255.2558,190
9127.129.0.0/19127.129.0.1 to 127.129.31.254127.129.31.2558,190
10127.129.32.0/19127.129.32.1 to 127.129.63.254127.129.63.2558,190
11127.129.64.0/19127.129.64.1 to 127.129.95.254127.129.95.2558,190
12127.129.96.0/19127.129.96.1 to 127.129.127.254127.129.127.2558,190
13127.129.128.0/19127.129.128.1 to 127.129.159.254127.129.159.2558,190
14127.129.160.0/19127.129.160.1 to 127.129.191.254127.129.191.2558,190
15127.129.192.0/19127.129.192.1 to 127.129.223.254127.129.223.2558,190
16127.129.224.0/19127.129.224.1 to 127.129.255.254127.129.255.2558,190
17127.130.0.0/19127.130.0.1 to 127.130.31.254127.130.31.2558,190
18127.130.32.0/19127.130.32.1 to 127.130.63.254127.130.63.2558,190
19127.130.64.0/19127.130.64.1 to 127.130.95.254127.130.95.2558,190
20127.130.96.0/19127.130.96.1 to 127.130.127.254127.130.127.2558,190
21127.130.128.0/19127.130.128.1 to 127.130.159.254127.130.159.2558,190
22127.130.160.0/19127.130.160.1 to 127.130.191.254127.130.191.2558,190
23127.130.192.0/19127.130.192.1 to 127.130.223.254127.130.223.2558,190
24127.130.224.0/19127.130.224.1 to 127.130.255.254127.130.255.2558,190
25127.131.0.0/19127.131.0.1 to 127.131.31.254127.131.31.2558,190
26127.131.32.0/19127.131.32.1 to 127.131.63.254127.131.63.2558,190
27127.131.64.0/19127.131.64.1 to 127.131.95.254127.131.95.2558,190
28127.131.96.0/19127.131.96.1 to 127.131.127.254127.131.127.2558,190
29127.131.128.0/19127.131.128.1 to 127.131.159.254127.131.159.2558,190
30127.131.160.0/19127.131.160.1 to 127.131.191.254127.131.191.2558,190
31127.131.192.0/19127.131.192.1 to 127.131.223.254127.131.223.2558,190
32127.131.224.0/19127.131.224.1 to 127.131.255.254127.131.255.2558,190
33127.132.0.0/19127.132.0.1 to 127.132.31.254127.132.31.2558,190
34127.132.32.0/19127.132.32.1 to 127.132.63.254127.132.63.2558,190
35127.132.64.0/19127.132.64.1 to 127.132.95.254127.132.95.2558,190
36127.132.96.0/19127.132.96.1 to 127.132.127.254127.132.127.2558,190
37127.132.128.0/19127.132.128.1 to 127.132.159.254127.132.159.2558,190
38127.132.160.0/19127.132.160.1 to 127.132.191.254127.132.191.2558,190
39127.132.192.0/19127.132.192.1 to 127.132.223.254127.132.223.2558,190
40127.132.224.0/19127.132.224.1 to 127.132.255.254127.132.255.2558,190
41127.133.0.0/19127.133.0.1 to 127.133.31.254127.133.31.2558,190
42127.133.32.0/19127.133.32.1 to 127.133.63.254127.133.63.2558,190
43127.133.64.0/19127.133.64.1 to 127.133.95.254127.133.95.2558,190
44127.133.96.0/19127.133.96.1 to 127.133.127.254127.133.127.2558,190
45127.133.128.0/19127.133.128.1 to 127.133.159.254127.133.159.2558,190
46127.133.160.0/19127.133.160.1 to 127.133.191.254127.133.191.2558,190
47127.133.192.0/19127.133.192.1 to 127.133.223.254127.133.223.2558,190
48127.133.224.0/19127.133.224.1 to 127.133.255.254127.133.255.2558,190
49127.134.0.0/19127.134.0.1 to 127.134.31.254127.134.31.2558,190
50127.134.32.0/19127.134.32.1 to 127.134.63.254127.134.63.2558,190
51127.134.64.0/19127.134.64.1 to 127.134.95.254127.134.95.2558,190
52127.134.96.0/19127.134.96.1 to 127.134.127.254127.134.127.2558,190
53127.134.128.0/19127.134.128.1 to 127.134.159.254127.134.159.2558,190
54127.134.160.0/19127.134.160.1 to 127.134.191.254127.134.191.2558,190
55127.134.192.0/19127.134.192.1 to 127.134.223.254127.134.223.2558,190
56127.134.224.0/19127.134.224.1 to 127.134.255.254127.134.255.2558,190
57127.135.0.0/19127.135.0.1 to 127.135.31.254127.135.31.2558,190
58127.135.32.0/19127.135.32.1 to 127.135.63.254127.135.63.2558,190
59127.135.64.0/19127.135.64.1 to 127.135.95.254127.135.95.2558,190
60127.135.96.0/19127.135.96.1 to 127.135.127.254127.135.127.2558,190
61127.135.128.0/19127.135.128.1 to 127.135.159.254127.135.159.2558,190
62127.135.160.0/19127.135.160.1 to 127.135.191.254127.135.191.2558,190
63127.135.192.0/19127.135.192.1 to 127.135.223.254127.135.223.2558,190
64127.135.224.0/19127.135.224.1 to 127.135.255.254127.135.255.2558,190
65127.136.0.0/19127.136.0.1 to 127.136.31.254127.136.31.2558,190
66127.136.32.0/19127.136.32.1 to 127.136.63.254127.136.63.2558,190
67127.136.64.0/19127.136.64.1 to 127.136.95.254127.136.95.2558,190
68127.136.96.0/19127.136.96.1 to 127.136.127.254127.136.127.2558,190
69127.136.128.0/19127.136.128.1 to 127.136.159.254127.136.159.2558,190
70127.136.160.0/19127.136.160.1 to 127.136.191.254127.136.191.2558,190
71127.136.192.0/19127.136.192.1 to 127.136.223.254127.136.223.2558,190
72127.136.224.0/19127.136.224.1 to 127.136.255.254127.136.255.2558,190
73127.137.0.0/19127.137.0.1 to 127.137.31.254127.137.31.2558,190
74127.137.32.0/19127.137.32.1 to 127.137.63.254127.137.63.2558,190
75127.137.64.0/19127.137.64.1 to 127.137.95.254127.137.95.2558,190
76127.137.96.0/19127.137.96.1 to 127.137.127.254127.137.127.2558,190
77127.137.128.0/19127.137.128.1 to 127.137.159.254127.137.159.2558,190
78127.137.160.0/19127.137.160.1 to 127.137.191.254127.137.191.2558,190
79127.137.192.0/19127.137.192.1 to 127.137.223.254127.137.223.2558,190
80127.137.224.0/19127.137.224.1 to 127.137.255.254127.137.255.2558,190
81127.138.0.0/19127.138.0.1 to 127.138.31.254127.138.31.2558,190
82127.138.32.0/19127.138.32.1 to 127.138.63.254127.138.63.2558,190
83127.138.64.0/19127.138.64.1 to 127.138.95.254127.138.95.2558,190
84127.138.96.0/19127.138.96.1 to 127.138.127.254127.138.127.2558,190
85127.138.128.0/19127.138.128.1 to 127.138.159.254127.138.159.2558,190
86127.138.160.0/19127.138.160.1 to 127.138.191.254127.138.191.2558,190
87127.138.192.0/19127.138.192.1 to 127.138.223.254127.138.223.2558,190
88127.138.224.0/19127.138.224.1 to 127.138.255.254127.138.255.2558,190
89127.139.0.0/19127.139.0.1 to 127.139.31.254127.139.31.2558,190
90127.139.32.0/19127.139.32.1 to 127.139.63.254127.139.63.2558,190
91127.139.64.0/19127.139.64.1 to 127.139.95.254127.139.95.2558,190
92127.139.96.0/19127.139.96.1 to 127.139.127.254127.139.127.2558,190
93127.139.128.0/19127.139.128.1 to 127.139.159.254127.139.159.2558,190
94127.139.160.0/19127.139.160.1 to 127.139.191.254127.139.191.2558,190
95127.139.192.0/19127.139.192.1 to 127.139.223.254127.139.223.2558,190
96127.139.224.0/19127.139.224.1 to 127.139.255.254127.139.255.2558,190
97127.140.0.0/19127.140.0.1 to 127.140.31.254127.140.31.2558,190
98127.140.32.0/19127.140.32.1 to 127.140.63.254127.140.63.2558,190
99127.140.64.0/19127.140.64.1 to 127.140.95.254127.140.95.2558,190
100127.140.96.0/19127.140.96.1 to 127.140.127.254127.140.127.2558,190
101127.140.128.0/19127.140.128.1 to 127.140.159.254127.140.159.2558,190
102127.140.160.0/19127.140.160.1 to 127.140.191.254127.140.191.2558,190
103127.140.192.0/19127.140.192.1 to 127.140.223.254127.140.223.2558,190
104127.140.224.0/19127.140.224.1 to 127.140.255.254127.140.255.2558,190
105127.141.0.0/19127.141.0.1 to 127.141.31.254127.141.31.2558,190
106127.141.32.0/19127.141.32.1 to 127.141.63.254127.141.63.2558,190
107127.141.64.0/19127.141.64.1 to 127.141.95.254127.141.95.2558,190
108127.141.96.0/19127.141.96.1 to 127.141.127.254127.141.127.2558,190
109127.141.128.0/19127.141.128.1 to 127.141.159.254127.141.159.2558,190
110127.141.160.0/19127.141.160.1 to 127.141.191.254127.141.191.2558,190
111127.141.192.0/19127.141.192.1 to 127.141.223.254127.141.223.2558,190
112127.141.224.0/19127.141.224.1 to 127.141.255.254127.141.255.2558,190
113127.142.0.0/19127.142.0.1 to 127.142.31.254127.142.31.2558,190
114127.142.32.0/19127.142.32.1 to 127.142.63.254127.142.63.2558,190
115127.142.64.0/19127.142.64.1 to 127.142.95.254127.142.95.2558,190
116127.142.96.0/19127.142.96.1 to 127.142.127.254127.142.127.2558,190
117127.142.128.0/19127.142.128.1 to 127.142.159.254127.142.159.2558,190
118127.142.160.0/19127.142.160.1 to 127.142.191.254127.142.191.2558,190
119127.142.192.0/19127.142.192.1 to 127.142.223.254127.142.223.2558,190
120127.142.224.0/19127.142.224.1 to 127.142.255.254127.142.255.2558,190
121127.143.0.0/19127.143.0.1 to 127.143.31.254127.143.31.2558,190
122127.143.32.0/19127.143.32.1 to 127.143.63.254127.143.63.2558,190
123127.143.64.0/19127.143.64.1 to 127.143.95.254127.143.95.2558,190
124127.143.96.0/19127.143.96.1 to 127.143.127.254127.143.127.2558,190
125127.143.128.0/19127.143.128.1 to 127.143.159.254127.143.159.2558,190
126127.143.160.0/19127.143.160.1 to 127.143.191.254127.143.191.2558,190
127127.143.192.0/19127.143.192.1 to 127.143.223.254127.143.223.2558,190
128127.143.224.0/19127.143.224.1 to 127.143.255.254127.143.255.2558,190
129127.144.0.0/19127.144.0.1 to 127.144.31.254127.144.31.2558,190
130127.144.32.0/19127.144.32.1 to 127.144.63.254127.144.63.2558,190
131127.144.64.0/19127.144.64.1 to 127.144.95.254127.144.95.2558,190
132127.144.96.0/19127.144.96.1 to 127.144.127.254127.144.127.2558,190
133127.144.128.0/19127.144.128.1 to 127.144.159.254127.144.159.2558,190
134127.144.160.0/19127.144.160.1 to 127.144.191.254127.144.191.2558,190
135127.144.192.0/19127.144.192.1 to 127.144.223.254127.144.223.2558,190
136127.144.224.0/19127.144.224.1 to 127.144.255.254127.144.255.2558,190
137127.145.0.0/19127.145.0.1 to 127.145.31.254127.145.31.2558,190
138127.145.32.0/19127.145.32.1 to 127.145.63.254127.145.63.2558,190
139127.145.64.0/19127.145.64.1 to 127.145.95.254127.145.95.2558,190
140127.145.96.0/19127.145.96.1 to 127.145.127.254127.145.127.2558,190
141127.145.128.0/19127.145.128.1 to 127.145.159.254127.145.159.2558,190
142127.145.160.0/19127.145.160.1 to 127.145.191.254127.145.191.2558,190
143127.145.192.0/19127.145.192.1 to 127.145.223.254127.145.223.2558,190
144127.145.224.0/19127.145.224.1 to 127.145.255.254127.145.255.2558,190
145127.146.0.0/19127.146.0.1 to 127.146.31.254127.146.31.2558,190
146127.146.32.0/19127.146.32.1 to 127.146.63.254127.146.63.2558,190
147127.146.64.0/19127.146.64.1 to 127.146.95.254127.146.95.2558,190
148127.146.96.0/19127.146.96.1 to 127.146.127.254127.146.127.2558,190
149127.146.128.0/19127.146.128.1 to 127.146.159.254127.146.159.2558,190
150127.146.160.0/19127.146.160.1 to 127.146.191.254127.146.191.2558,190
151127.146.192.0/19127.146.192.1 to 127.146.223.254127.146.223.2558,190
152127.146.224.0/19127.146.224.1 to 127.146.255.254127.146.255.2558,190
153127.147.0.0/19127.147.0.1 to 127.147.31.254127.147.31.2558,190
154127.147.32.0/19127.147.32.1 to 127.147.63.254127.147.63.2558,190
155127.147.64.0/19127.147.64.1 to 127.147.95.254127.147.95.2558,190
156127.147.96.0/19127.147.96.1 to 127.147.127.254127.147.127.2558,190
157127.147.128.0/19127.147.128.1 to 127.147.159.254127.147.159.2558,190
158127.147.160.0/19127.147.160.1 to 127.147.191.254127.147.191.2558,190
159127.147.192.0/19127.147.192.1 to 127.147.223.254127.147.223.2558,190
160127.147.224.0/19127.147.224.1 to 127.147.255.254127.147.255.2558,190
161127.148.0.0/19127.148.0.1 to 127.148.31.254127.148.31.2558,190
162127.148.32.0/19127.148.32.1 to 127.148.63.254127.148.63.2558,190
163127.148.64.0/19127.148.64.1 to 127.148.95.254127.148.95.2558,190
164127.148.96.0/19127.148.96.1 to 127.148.127.254127.148.127.2558,190
165127.148.128.0/19127.148.128.1 to 127.148.159.254127.148.159.2558,190
166127.148.160.0/19127.148.160.1 to 127.148.191.254127.148.191.2558,190
167127.148.192.0/19127.148.192.1 to 127.148.223.254127.148.223.2558,190
168127.148.224.0/19127.148.224.1 to 127.148.255.254127.148.255.2558,190
169127.149.0.0/19127.149.0.1 to 127.149.31.254127.149.31.2558,190
170127.149.32.0/19127.149.32.1 to 127.149.63.254127.149.63.2558,190
171127.149.64.0/19127.149.64.1 to 127.149.95.254127.149.95.2558,190
172127.149.96.0/19127.149.96.1 to 127.149.127.254127.149.127.2558,190
173127.149.128.0/19127.149.128.1 to 127.149.159.254127.149.159.2558,190
174127.149.160.0/19127.149.160.1 to 127.149.191.254127.149.191.2558,190
175127.149.192.0/19127.149.192.1 to 127.149.223.254127.149.223.2558,190
176127.149.224.0/19127.149.224.1 to 127.149.255.254127.149.255.2558,190
177127.150.0.0/19127.150.0.1 to 127.150.31.254127.150.31.2558,190
178127.150.32.0/19127.150.32.1 to 127.150.63.254127.150.63.2558,190
179127.150.64.0/19127.150.64.1 to 127.150.95.254127.150.95.2558,190
180127.150.96.0/19127.150.96.1 to 127.150.127.254127.150.127.2558,190
181127.150.128.0/19127.150.128.1 to 127.150.159.254127.150.159.2558,190
182127.150.160.0/19127.150.160.1 to 127.150.191.254127.150.191.2558,190
183127.150.192.0/19127.150.192.1 to 127.150.223.254127.150.223.2558,190
184127.150.224.0/19127.150.224.1 to 127.150.255.254127.150.255.2558,190
185127.151.0.0/19127.151.0.1 to 127.151.31.254127.151.31.2558,190
186127.151.32.0/19127.151.32.1 to 127.151.63.254127.151.63.2558,190
187127.151.64.0/19127.151.64.1 to 127.151.95.254127.151.95.2558,190
188127.151.96.0/19127.151.96.1 to 127.151.127.254127.151.127.2558,190
189127.151.128.0/19127.151.128.1 to 127.151.159.254127.151.159.2558,190
190127.151.160.0/19127.151.160.1 to 127.151.191.254127.151.191.2558,190
191127.151.192.0/19127.151.192.1 to 127.151.223.254127.151.223.2558,190
192127.151.224.0/19127.151.224.1 to 127.151.255.254127.151.255.2558,190
193127.152.0.0/19127.152.0.1 to 127.152.31.254127.152.31.2558,190
194127.152.32.0/19127.152.32.1 to 127.152.63.254127.152.63.2558,190
195127.152.64.0/19127.152.64.1 to 127.152.95.254127.152.95.2558,190
196127.152.96.0/19127.152.96.1 to 127.152.127.254127.152.127.2558,190
197127.152.128.0/19127.152.128.1 to 127.152.159.254127.152.159.2558,190
198127.152.160.0/19127.152.160.1 to 127.152.191.254127.152.191.2558,190
199127.152.192.0/19127.152.192.1 to 127.152.223.254127.152.223.2558,190
200127.152.224.0/19127.152.224.1 to 127.152.255.254127.152.255.2558,190
201127.153.0.0/19127.153.0.1 to 127.153.31.254127.153.31.2558,190
202127.153.32.0/19127.153.32.1 to 127.153.63.254127.153.63.2558,190
203127.153.64.0/19127.153.64.1 to 127.153.95.254127.153.95.2558,190
204127.153.96.0/19127.153.96.1 to 127.153.127.254127.153.127.2558,190
205127.153.128.0/19127.153.128.1 to 127.153.159.254127.153.159.2558,190
206127.153.160.0/19127.153.160.1 to 127.153.191.254127.153.191.2558,190
207127.153.192.0/19127.153.192.1 to 127.153.223.254127.153.223.2558,190
208127.153.224.0/19127.153.224.1 to 127.153.255.254127.153.255.2558,190
209127.154.0.0/19127.154.0.1 to 127.154.31.254127.154.31.2558,190
210127.154.32.0/19127.154.32.1 to 127.154.63.254127.154.63.2558,190
211127.154.64.0/19127.154.64.1 to 127.154.95.254127.154.95.2558,190
212127.154.96.0/19127.154.96.1 to 127.154.127.254127.154.127.2558,190
213127.154.128.0/19127.154.128.1 to 127.154.159.254127.154.159.2558,190
214127.154.160.0/19127.154.160.1 to 127.154.191.254127.154.191.2558,190
215127.154.192.0/19127.154.192.1 to 127.154.223.254127.154.223.2558,190
216127.154.224.0/19127.154.224.1 to 127.154.255.254127.154.255.2558,190
217127.155.0.0/19127.155.0.1 to 127.155.31.254127.155.31.2558,190
218127.155.32.0/19127.155.32.1 to 127.155.63.254127.155.63.2558,190
219127.155.64.0/19127.155.64.1 to 127.155.95.254127.155.95.2558,190
220127.155.96.0/19127.155.96.1 to 127.155.127.254127.155.127.2558,190
221127.155.128.0/19127.155.128.1 to 127.155.159.254127.155.159.2558,190
222127.155.160.0/19127.155.160.1 to 127.155.191.254127.155.191.2558,190
223127.155.192.0/19127.155.192.1 to 127.155.223.254127.155.223.2558,190
224127.155.224.0/19127.155.224.1 to 127.155.255.254127.155.255.2558,190
225127.156.0.0/19127.156.0.1 to 127.156.31.254127.156.31.2558,190
226127.156.32.0/19127.156.32.1 to 127.156.63.254127.156.63.2558,190
227127.156.64.0/19127.156.64.1 to 127.156.95.254127.156.95.2558,190
228127.156.96.0/19127.156.96.1 to 127.156.127.254127.156.127.2558,190
229127.156.128.0/19127.156.128.1 to 127.156.159.254127.156.159.2558,190
230127.156.160.0/19127.156.160.1 to 127.156.191.254127.156.191.2558,190
231127.156.192.0/19127.156.192.1 to 127.156.223.254127.156.223.2558,190
232127.156.224.0/19127.156.224.1 to 127.156.255.254127.156.255.2558,190
233127.157.0.0/19127.157.0.1 to 127.157.31.254127.157.31.2558,190
234127.157.32.0/19127.157.32.1 to 127.157.63.254127.157.63.2558,190
235127.157.64.0/19127.157.64.1 to 127.157.95.254127.157.95.2558,190
236127.157.96.0/19127.157.96.1 to 127.157.127.254127.157.127.2558,190
237127.157.128.0/19127.157.128.1 to 127.157.159.254127.157.159.2558,190
238127.157.160.0/19127.157.160.1 to 127.157.191.254127.157.191.2558,190
239127.157.192.0/19127.157.192.1 to 127.157.223.254127.157.223.2558,190
240127.157.224.0/19127.157.224.1 to 127.157.255.254127.157.255.2558,190
241127.158.0.0/19127.158.0.1 to 127.158.31.254127.158.31.2558,190
242127.158.32.0/19127.158.32.1 to 127.158.63.254127.158.63.2558,190
243127.158.64.0/19127.158.64.1 to 127.158.95.254127.158.95.2558,190
244127.158.96.0/19127.158.96.1 to 127.158.127.254127.158.127.2558,190
245127.158.128.0/19127.158.128.1 to 127.158.159.254127.158.159.2558,190
246127.158.160.0/19127.158.160.1 to 127.158.191.254127.158.191.2558,190
247127.158.192.0/19127.158.192.1 to 127.158.223.254127.158.223.2558,190
248127.158.224.0/19127.158.224.1 to 127.158.255.254127.158.255.2558,190
249127.159.0.0/19127.159.0.1 to 127.159.31.254127.159.31.2558,190
250127.159.32.0/19127.159.32.1 to 127.159.63.254127.159.63.2558,190
251127.159.64.0/19127.159.64.1 to 127.159.95.254127.159.95.2558,190
252127.159.96.0/19127.159.96.1 to 127.159.127.254127.159.127.2558,190
253127.159.128.0/19127.159.128.1 to 127.159.159.254127.159.159.2558,190
254127.159.160.0/19127.159.160.1 to 127.159.191.254127.159.191.2558,190
255127.159.192.0/19127.159.192.1 to 127.159.223.254127.159.223.2558,190
256127.159.224.0/19127.159.224.1 to 127.159.255.254127.159.255.2558,190

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.