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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.

Network127.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
127.0.0.0
Broadcast address
127.255.255.255
First usable
127.0.0.1
Last usable
127.255.255.254
Usable hosts
16,777,214 (16,777,216 less the network and broadcast addresses)
Subnet mask
255.0.0.0
Wildcard mask
0.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/8
Type
Loopback 127.0.0.0/8
This computer
Old class
A (default /8)
As numbers
Hex 7F000000 · Integer 2130706432 to 2147483647
Reverse DNS zone
127.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01111111..00000000.00000000.00000000127.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network01111111..00000000.00000000.00000000127.0.0.0
Broadcast01111111..11111111.11111111.11111111127.255.255.255
Split into smaller subnets/18
/9 (2)/10 (4)/11 (8)/12 (16)/13 (32)/14 (64)/15 (128)/16 (256)/17 (512)/18 (1,024)/19 (2,048)/20 (4,096)

127.0.0.0/8 makes 1,024 subnets of /18; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1127.0.0.0/18127.0.0.1 to 127.0.63.254127.0.63.25516,382
2127.0.64.0/18127.0.64.1 to 127.0.127.254127.0.127.25516,382
3127.0.128.0/18127.0.128.1 to 127.0.191.254127.0.191.25516,382
4127.0.192.0/18127.0.192.1 to 127.0.255.254127.0.255.25516,382
5127.1.0.0/18127.1.0.1 to 127.1.63.254127.1.63.25516,382
6127.1.64.0/18127.1.64.1 to 127.1.127.254127.1.127.25516,382
7127.1.128.0/18127.1.128.1 to 127.1.191.254127.1.191.25516,382
8127.1.192.0/18127.1.192.1 to 127.1.255.254127.1.255.25516,382
9127.2.0.0/18127.2.0.1 to 127.2.63.254127.2.63.25516,382
10127.2.64.0/18127.2.64.1 to 127.2.127.254127.2.127.25516,382
11127.2.128.0/18127.2.128.1 to 127.2.191.254127.2.191.25516,382
12127.2.192.0/18127.2.192.1 to 127.2.255.254127.2.255.25516,382
13127.3.0.0/18127.3.0.1 to 127.3.63.254127.3.63.25516,382
14127.3.64.0/18127.3.64.1 to 127.3.127.254127.3.127.25516,382
15127.3.128.0/18127.3.128.1 to 127.3.191.254127.3.191.25516,382
16127.3.192.0/18127.3.192.1 to 127.3.255.254127.3.255.25516,382
17127.4.0.0/18127.4.0.1 to 127.4.63.254127.4.63.25516,382
18127.4.64.0/18127.4.64.1 to 127.4.127.254127.4.127.25516,382
19127.4.128.0/18127.4.128.1 to 127.4.191.254127.4.191.25516,382
20127.4.192.0/18127.4.192.1 to 127.4.255.254127.4.255.25516,382
21127.5.0.0/18127.5.0.1 to 127.5.63.254127.5.63.25516,382
22127.5.64.0/18127.5.64.1 to 127.5.127.254127.5.127.25516,382
23127.5.128.0/18127.5.128.1 to 127.5.191.254127.5.191.25516,382
24127.5.192.0/18127.5.192.1 to 127.5.255.254127.5.255.25516,382
25127.6.0.0/18127.6.0.1 to 127.6.63.254127.6.63.25516,382
26127.6.64.0/18127.6.64.1 to 127.6.127.254127.6.127.25516,382
27127.6.128.0/18127.6.128.1 to 127.6.191.254127.6.191.25516,382
28127.6.192.0/18127.6.192.1 to 127.6.255.254127.6.255.25516,382
29127.7.0.0/18127.7.0.1 to 127.7.63.254127.7.63.25516,382
30127.7.64.0/18127.7.64.1 to 127.7.127.254127.7.127.25516,382
31127.7.128.0/18127.7.128.1 to 127.7.191.254127.7.191.25516,382
32127.7.192.0/18127.7.192.1 to 127.7.255.254127.7.255.25516,382
33127.8.0.0/18127.8.0.1 to 127.8.63.254127.8.63.25516,382
34127.8.64.0/18127.8.64.1 to 127.8.127.254127.8.127.25516,382
35127.8.128.0/18127.8.128.1 to 127.8.191.254127.8.191.25516,382
36127.8.192.0/18127.8.192.1 to 127.8.255.254127.8.255.25516,382
37127.9.0.0/18127.9.0.1 to 127.9.63.254127.9.63.25516,382
38127.9.64.0/18127.9.64.1 to 127.9.127.254127.9.127.25516,382
39127.9.128.0/18127.9.128.1 to 127.9.191.254127.9.191.25516,382
40127.9.192.0/18127.9.192.1 to 127.9.255.254127.9.255.25516,382
41127.10.0.0/18127.10.0.1 to 127.10.63.254127.10.63.25516,382
42127.10.64.0/18127.10.64.1 to 127.10.127.254127.10.127.25516,382
43127.10.128.0/18127.10.128.1 to 127.10.191.254127.10.191.25516,382
44127.10.192.0/18127.10.192.1 to 127.10.255.254127.10.255.25516,382
45127.11.0.0/18127.11.0.1 to 127.11.63.254127.11.63.25516,382
46127.11.64.0/18127.11.64.1 to 127.11.127.254127.11.127.25516,382
47127.11.128.0/18127.11.128.1 to 127.11.191.254127.11.191.25516,382
48127.11.192.0/18127.11.192.1 to 127.11.255.254127.11.255.25516,382
49127.12.0.0/18127.12.0.1 to 127.12.63.254127.12.63.25516,382
50127.12.64.0/18127.12.64.1 to 127.12.127.254127.12.127.25516,382
51127.12.128.0/18127.12.128.1 to 127.12.191.254127.12.191.25516,382
52127.12.192.0/18127.12.192.1 to 127.12.255.254127.12.255.25516,382
53127.13.0.0/18127.13.0.1 to 127.13.63.254127.13.63.25516,382
54127.13.64.0/18127.13.64.1 to 127.13.127.254127.13.127.25516,382
55127.13.128.0/18127.13.128.1 to 127.13.191.254127.13.191.25516,382
56127.13.192.0/18127.13.192.1 to 127.13.255.254127.13.255.25516,382
57127.14.0.0/18127.14.0.1 to 127.14.63.254127.14.63.25516,382
58127.14.64.0/18127.14.64.1 to 127.14.127.254127.14.127.25516,382
59127.14.128.0/18127.14.128.1 to 127.14.191.254127.14.191.25516,382
60127.14.192.0/18127.14.192.1 to 127.14.255.254127.14.255.25516,382
61127.15.0.0/18127.15.0.1 to 127.15.63.254127.15.63.25516,382
62127.15.64.0/18127.15.64.1 to 127.15.127.254127.15.127.25516,382
63127.15.128.0/18127.15.128.1 to 127.15.191.254127.15.191.25516,382
64127.15.192.0/18127.15.192.1 to 127.15.255.254127.15.255.25516,382
65127.16.0.0/18127.16.0.1 to 127.16.63.254127.16.63.25516,382
66127.16.64.0/18127.16.64.1 to 127.16.127.254127.16.127.25516,382
67127.16.128.0/18127.16.128.1 to 127.16.191.254127.16.191.25516,382
68127.16.192.0/18127.16.192.1 to 127.16.255.254127.16.255.25516,382
69127.17.0.0/18127.17.0.1 to 127.17.63.254127.17.63.25516,382
70127.17.64.0/18127.17.64.1 to 127.17.127.254127.17.127.25516,382
71127.17.128.0/18127.17.128.1 to 127.17.191.254127.17.191.25516,382
72127.17.192.0/18127.17.192.1 to 127.17.255.254127.17.255.25516,382
73127.18.0.0/18127.18.0.1 to 127.18.63.254127.18.63.25516,382
74127.18.64.0/18127.18.64.1 to 127.18.127.254127.18.127.25516,382
75127.18.128.0/18127.18.128.1 to 127.18.191.254127.18.191.25516,382
76127.18.192.0/18127.18.192.1 to 127.18.255.254127.18.255.25516,382
77127.19.0.0/18127.19.0.1 to 127.19.63.254127.19.63.25516,382
78127.19.64.0/18127.19.64.1 to 127.19.127.254127.19.127.25516,382
79127.19.128.0/18127.19.128.1 to 127.19.191.254127.19.191.25516,382
80127.19.192.0/18127.19.192.1 to 127.19.255.254127.19.255.25516,382
81127.20.0.0/18127.20.0.1 to 127.20.63.254127.20.63.25516,382
82127.20.64.0/18127.20.64.1 to 127.20.127.254127.20.127.25516,382
83127.20.128.0/18127.20.128.1 to 127.20.191.254127.20.191.25516,382
84127.20.192.0/18127.20.192.1 to 127.20.255.254127.20.255.25516,382
85127.21.0.0/18127.21.0.1 to 127.21.63.254127.21.63.25516,382
86127.21.64.0/18127.21.64.1 to 127.21.127.254127.21.127.25516,382
87127.21.128.0/18127.21.128.1 to 127.21.191.254127.21.191.25516,382
88127.21.192.0/18127.21.192.1 to 127.21.255.254127.21.255.25516,382
89127.22.0.0/18127.22.0.1 to 127.22.63.254127.22.63.25516,382
90127.22.64.0/18127.22.64.1 to 127.22.127.254127.22.127.25516,382
91127.22.128.0/18127.22.128.1 to 127.22.191.254127.22.191.25516,382
92127.22.192.0/18127.22.192.1 to 127.22.255.254127.22.255.25516,382
93127.23.0.0/18127.23.0.1 to 127.23.63.254127.23.63.25516,382
94127.23.64.0/18127.23.64.1 to 127.23.127.254127.23.127.25516,382
95127.23.128.0/18127.23.128.1 to 127.23.191.254127.23.191.25516,382
96127.23.192.0/18127.23.192.1 to 127.23.255.254127.23.255.25516,382
97127.24.0.0/18127.24.0.1 to 127.24.63.254127.24.63.25516,382
98127.24.64.0/18127.24.64.1 to 127.24.127.254127.24.127.25516,382
99127.24.128.0/18127.24.128.1 to 127.24.191.254127.24.191.25516,382
100127.24.192.0/18127.24.192.1 to 127.24.255.254127.24.255.25516,382
101127.25.0.0/18127.25.0.1 to 127.25.63.254127.25.63.25516,382
102127.25.64.0/18127.25.64.1 to 127.25.127.254127.25.127.25516,382
103127.25.128.0/18127.25.128.1 to 127.25.191.254127.25.191.25516,382
104127.25.192.0/18127.25.192.1 to 127.25.255.254127.25.255.25516,382
105127.26.0.0/18127.26.0.1 to 127.26.63.254127.26.63.25516,382
106127.26.64.0/18127.26.64.1 to 127.26.127.254127.26.127.25516,382
107127.26.128.0/18127.26.128.1 to 127.26.191.254127.26.191.25516,382
108127.26.192.0/18127.26.192.1 to 127.26.255.254127.26.255.25516,382
109127.27.0.0/18127.27.0.1 to 127.27.63.254127.27.63.25516,382
110127.27.64.0/18127.27.64.1 to 127.27.127.254127.27.127.25516,382
111127.27.128.0/18127.27.128.1 to 127.27.191.254127.27.191.25516,382
112127.27.192.0/18127.27.192.1 to 127.27.255.254127.27.255.25516,382
113127.28.0.0/18127.28.0.1 to 127.28.63.254127.28.63.25516,382
114127.28.64.0/18127.28.64.1 to 127.28.127.254127.28.127.25516,382
115127.28.128.0/18127.28.128.1 to 127.28.191.254127.28.191.25516,382
116127.28.192.0/18127.28.192.1 to 127.28.255.254127.28.255.25516,382
117127.29.0.0/18127.29.0.1 to 127.29.63.254127.29.63.25516,382
118127.29.64.0/18127.29.64.1 to 127.29.127.254127.29.127.25516,382
119127.29.128.0/18127.29.128.1 to 127.29.191.254127.29.191.25516,382
120127.29.192.0/18127.29.192.1 to 127.29.255.254127.29.255.25516,382
121127.30.0.0/18127.30.0.1 to 127.30.63.254127.30.63.25516,382
122127.30.64.0/18127.30.64.1 to 127.30.127.254127.30.127.25516,382
123127.30.128.0/18127.30.128.1 to 127.30.191.254127.30.191.25516,382
124127.30.192.0/18127.30.192.1 to 127.30.255.254127.30.255.25516,382
125127.31.0.0/18127.31.0.1 to 127.31.63.254127.31.63.25516,382
126127.31.64.0/18127.31.64.1 to 127.31.127.254127.31.127.25516,382
127127.31.128.0/18127.31.128.1 to 127.31.191.254127.31.191.25516,382
128127.31.192.0/18127.31.192.1 to 127.31.255.254127.31.255.25516,382
129127.32.0.0/18127.32.0.1 to 127.32.63.254127.32.63.25516,382
130127.32.64.0/18127.32.64.1 to 127.32.127.254127.32.127.25516,382
131127.32.128.0/18127.32.128.1 to 127.32.191.254127.32.191.25516,382
132127.32.192.0/18127.32.192.1 to 127.32.255.254127.32.255.25516,382
133127.33.0.0/18127.33.0.1 to 127.33.63.254127.33.63.25516,382
134127.33.64.0/18127.33.64.1 to 127.33.127.254127.33.127.25516,382
135127.33.128.0/18127.33.128.1 to 127.33.191.254127.33.191.25516,382
136127.33.192.0/18127.33.192.1 to 127.33.255.254127.33.255.25516,382
137127.34.0.0/18127.34.0.1 to 127.34.63.254127.34.63.25516,382
138127.34.64.0/18127.34.64.1 to 127.34.127.254127.34.127.25516,382
139127.34.128.0/18127.34.128.1 to 127.34.191.254127.34.191.25516,382
140127.34.192.0/18127.34.192.1 to 127.34.255.254127.34.255.25516,382
141127.35.0.0/18127.35.0.1 to 127.35.63.254127.35.63.25516,382
142127.35.64.0/18127.35.64.1 to 127.35.127.254127.35.127.25516,382
143127.35.128.0/18127.35.128.1 to 127.35.191.254127.35.191.25516,382
144127.35.192.0/18127.35.192.1 to 127.35.255.254127.35.255.25516,382
145127.36.0.0/18127.36.0.1 to 127.36.63.254127.36.63.25516,382
146127.36.64.0/18127.36.64.1 to 127.36.127.254127.36.127.25516,382
147127.36.128.0/18127.36.128.1 to 127.36.191.254127.36.191.25516,382
148127.36.192.0/18127.36.192.1 to 127.36.255.254127.36.255.25516,382
149127.37.0.0/18127.37.0.1 to 127.37.63.254127.37.63.25516,382
150127.37.64.0/18127.37.64.1 to 127.37.127.254127.37.127.25516,382
151127.37.128.0/18127.37.128.1 to 127.37.191.254127.37.191.25516,382
152127.37.192.0/18127.37.192.1 to 127.37.255.254127.37.255.25516,382
153127.38.0.0/18127.38.0.1 to 127.38.63.254127.38.63.25516,382
154127.38.64.0/18127.38.64.1 to 127.38.127.254127.38.127.25516,382
155127.38.128.0/18127.38.128.1 to 127.38.191.254127.38.191.25516,382
156127.38.192.0/18127.38.192.1 to 127.38.255.254127.38.255.25516,382
157127.39.0.0/18127.39.0.1 to 127.39.63.254127.39.63.25516,382
158127.39.64.0/18127.39.64.1 to 127.39.127.254127.39.127.25516,382
159127.39.128.0/18127.39.128.1 to 127.39.191.254127.39.191.25516,382
160127.39.192.0/18127.39.192.1 to 127.39.255.254127.39.255.25516,382
161127.40.0.0/18127.40.0.1 to 127.40.63.254127.40.63.25516,382
162127.40.64.0/18127.40.64.1 to 127.40.127.254127.40.127.25516,382
163127.40.128.0/18127.40.128.1 to 127.40.191.254127.40.191.25516,382
164127.40.192.0/18127.40.192.1 to 127.40.255.254127.40.255.25516,382
165127.41.0.0/18127.41.0.1 to 127.41.63.254127.41.63.25516,382
166127.41.64.0/18127.41.64.1 to 127.41.127.254127.41.127.25516,382
167127.41.128.0/18127.41.128.1 to 127.41.191.254127.41.191.25516,382
168127.41.192.0/18127.41.192.1 to 127.41.255.254127.41.255.25516,382
169127.42.0.0/18127.42.0.1 to 127.42.63.254127.42.63.25516,382
170127.42.64.0/18127.42.64.1 to 127.42.127.254127.42.127.25516,382
171127.42.128.0/18127.42.128.1 to 127.42.191.254127.42.191.25516,382
172127.42.192.0/18127.42.192.1 to 127.42.255.254127.42.255.25516,382
173127.43.0.0/18127.43.0.1 to 127.43.63.254127.43.63.25516,382
174127.43.64.0/18127.43.64.1 to 127.43.127.254127.43.127.25516,382
175127.43.128.0/18127.43.128.1 to 127.43.191.254127.43.191.25516,382
176127.43.192.0/18127.43.192.1 to 127.43.255.254127.43.255.25516,382
177127.44.0.0/18127.44.0.1 to 127.44.63.254127.44.63.25516,382
178127.44.64.0/18127.44.64.1 to 127.44.127.254127.44.127.25516,382
179127.44.128.0/18127.44.128.1 to 127.44.191.254127.44.191.25516,382
180127.44.192.0/18127.44.192.1 to 127.44.255.254127.44.255.25516,382
181127.45.0.0/18127.45.0.1 to 127.45.63.254127.45.63.25516,382
182127.45.64.0/18127.45.64.1 to 127.45.127.254127.45.127.25516,382
183127.45.128.0/18127.45.128.1 to 127.45.191.254127.45.191.25516,382
184127.45.192.0/18127.45.192.1 to 127.45.255.254127.45.255.25516,382
185127.46.0.0/18127.46.0.1 to 127.46.63.254127.46.63.25516,382
186127.46.64.0/18127.46.64.1 to 127.46.127.254127.46.127.25516,382
187127.46.128.0/18127.46.128.1 to 127.46.191.254127.46.191.25516,382
188127.46.192.0/18127.46.192.1 to 127.46.255.254127.46.255.25516,382
189127.47.0.0/18127.47.0.1 to 127.47.63.254127.47.63.25516,382
190127.47.64.0/18127.47.64.1 to 127.47.127.254127.47.127.25516,382
191127.47.128.0/18127.47.128.1 to 127.47.191.254127.47.191.25516,382
192127.47.192.0/18127.47.192.1 to 127.47.255.254127.47.255.25516,382
193127.48.0.0/18127.48.0.1 to 127.48.63.254127.48.63.25516,382
194127.48.64.0/18127.48.64.1 to 127.48.127.254127.48.127.25516,382
195127.48.128.0/18127.48.128.1 to 127.48.191.254127.48.191.25516,382
196127.48.192.0/18127.48.192.1 to 127.48.255.254127.48.255.25516,382
197127.49.0.0/18127.49.0.1 to 127.49.63.254127.49.63.25516,382
198127.49.64.0/18127.49.64.1 to 127.49.127.254127.49.127.25516,382
199127.49.128.0/18127.49.128.1 to 127.49.191.254127.49.191.25516,382
200127.49.192.0/18127.49.192.1 to 127.49.255.254127.49.255.25516,382
201127.50.0.0/18127.50.0.1 to 127.50.63.254127.50.63.25516,382
202127.50.64.0/18127.50.64.1 to 127.50.127.254127.50.127.25516,382
203127.50.128.0/18127.50.128.1 to 127.50.191.254127.50.191.25516,382
204127.50.192.0/18127.50.192.1 to 127.50.255.254127.50.255.25516,382
205127.51.0.0/18127.51.0.1 to 127.51.63.254127.51.63.25516,382
206127.51.64.0/18127.51.64.1 to 127.51.127.254127.51.127.25516,382
207127.51.128.0/18127.51.128.1 to 127.51.191.254127.51.191.25516,382
208127.51.192.0/18127.51.192.1 to 127.51.255.254127.51.255.25516,382
209127.52.0.0/18127.52.0.1 to 127.52.63.254127.52.63.25516,382
210127.52.64.0/18127.52.64.1 to 127.52.127.254127.52.127.25516,382
211127.52.128.0/18127.52.128.1 to 127.52.191.254127.52.191.25516,382
212127.52.192.0/18127.52.192.1 to 127.52.255.254127.52.255.25516,382
213127.53.0.0/18127.53.0.1 to 127.53.63.254127.53.63.25516,382
214127.53.64.0/18127.53.64.1 to 127.53.127.254127.53.127.25516,382
215127.53.128.0/18127.53.128.1 to 127.53.191.254127.53.191.25516,382
216127.53.192.0/18127.53.192.1 to 127.53.255.254127.53.255.25516,382
217127.54.0.0/18127.54.0.1 to 127.54.63.254127.54.63.25516,382
218127.54.64.0/18127.54.64.1 to 127.54.127.254127.54.127.25516,382
219127.54.128.0/18127.54.128.1 to 127.54.191.254127.54.191.25516,382
220127.54.192.0/18127.54.192.1 to 127.54.255.254127.54.255.25516,382
221127.55.0.0/18127.55.0.1 to 127.55.63.254127.55.63.25516,382
222127.55.64.0/18127.55.64.1 to 127.55.127.254127.55.127.25516,382
223127.55.128.0/18127.55.128.1 to 127.55.191.254127.55.191.25516,382
224127.55.192.0/18127.55.192.1 to 127.55.255.254127.55.255.25516,382
225127.56.0.0/18127.56.0.1 to 127.56.63.254127.56.63.25516,382
226127.56.64.0/18127.56.64.1 to 127.56.127.254127.56.127.25516,382
227127.56.128.0/18127.56.128.1 to 127.56.191.254127.56.191.25516,382
228127.56.192.0/18127.56.192.1 to 127.56.255.254127.56.255.25516,382
229127.57.0.0/18127.57.0.1 to 127.57.63.254127.57.63.25516,382
230127.57.64.0/18127.57.64.1 to 127.57.127.254127.57.127.25516,382
231127.57.128.0/18127.57.128.1 to 127.57.191.254127.57.191.25516,382
232127.57.192.0/18127.57.192.1 to 127.57.255.254127.57.255.25516,382
233127.58.0.0/18127.58.0.1 to 127.58.63.254127.58.63.25516,382
234127.58.64.0/18127.58.64.1 to 127.58.127.254127.58.127.25516,382
235127.58.128.0/18127.58.128.1 to 127.58.191.254127.58.191.25516,382
236127.58.192.0/18127.58.192.1 to 127.58.255.254127.58.255.25516,382
237127.59.0.0/18127.59.0.1 to 127.59.63.254127.59.63.25516,382
238127.59.64.0/18127.59.64.1 to 127.59.127.254127.59.127.25516,382
239127.59.128.0/18127.59.128.1 to 127.59.191.254127.59.191.25516,382
240127.59.192.0/18127.59.192.1 to 127.59.255.254127.59.255.25516,382
241127.60.0.0/18127.60.0.1 to 127.60.63.254127.60.63.25516,382
242127.60.64.0/18127.60.64.1 to 127.60.127.254127.60.127.25516,382
243127.60.128.0/18127.60.128.1 to 127.60.191.254127.60.191.25516,382
244127.60.192.0/18127.60.192.1 to 127.60.255.254127.60.255.25516,382
245127.61.0.0/18127.61.0.1 to 127.61.63.254127.61.63.25516,382
246127.61.64.0/18127.61.64.1 to 127.61.127.254127.61.127.25516,382
247127.61.128.0/18127.61.128.1 to 127.61.191.254127.61.191.25516,382
248127.61.192.0/18127.61.192.1 to 127.61.255.254127.61.255.25516,382
249127.62.0.0/18127.62.0.1 to 127.62.63.254127.62.63.25516,382
250127.62.64.0/18127.62.64.1 to 127.62.127.254127.62.127.25516,382
251127.62.128.0/18127.62.128.1 to 127.62.191.254127.62.191.25516,382
252127.62.192.0/18127.62.192.1 to 127.62.255.254127.62.255.25516,382
253127.63.0.0/18127.63.0.1 to 127.63.63.254127.63.63.25516,382
254127.63.64.0/18127.63.64.1 to 127.63.127.254127.63.127.25516,382
255127.63.128.0/18127.63.128.1 to 127.63.191.254127.63.191.25516,382
256127.63.192.0/18127.63.192.1 to 127.63.255.254127.63.255.25516,382

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.