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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.

Network207.0.0.0/9
Usable hosts8,388,606
Subnet mask255.128.0.0
Addresses8,388,608
Network address
207.0.0.0
Broadcast address
207.127.255.255
First usable
207.0.0.1
Last usable
207.127.255.254
Usable hosts
8,388,606 (8,388,608 less the network and broadcast addresses)
Subnet mask
255.128.0.0
Wildcard mask
0.127.255.255 (Cisco ACLs, OSPF)
Prefix length
/9
Type
Public public
Old class
C (default /24)
As numbers
Hex CF000000 · Integer 3472883712 to 3481272319
Reverse DNS zones
0.207.in-addr.arpa
1.207.in-addr.arpa
2.207.in-addr.arpa
3.207.in-addr.arpa
4.207.in-addr.arpa
5.207.in-addr.arpa
6.207.in-addr.arpa
7.207.in-addr.arpa
8.207.in-addr.arpa
9.207.in-addr.arpa
10.207.in-addr.arpa
11.207.in-addr.arpa
12.207.in-addr.arpa
13.207.in-addr.arpa
14.207.in-addr.arpa
15.207.in-addr.arpa
and 112 more
/9 is not on a 8-bit boundary, so it takes 128 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11001111.00000000.00000000.00000000207.0.0.0
Subnet mask11111111.10000000.00000000.00000000255.128.0.0
Network11001111.00000000.00000000.00000000207.0.0.0
Broadcast11001111.01111111.11111111.11111111207.127.255.255
Split into smaller subnets/19
/10 (2)/11 (4)/12 (8)/13 (16)/14 (32)/15 (64)/16 (128)/17 (256)/18 (512)/19 (1,024)/20 (2,048)/21 (4,096)

207.0.0.0/9 makes 1,024 subnets of /19; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1207.0.0.0/19207.0.0.1 to 207.0.31.254207.0.31.2558,190
2207.0.32.0/19207.0.32.1 to 207.0.63.254207.0.63.2558,190
3207.0.64.0/19207.0.64.1 to 207.0.95.254207.0.95.2558,190
4207.0.96.0/19207.0.96.1 to 207.0.127.254207.0.127.2558,190
5207.0.128.0/19207.0.128.1 to 207.0.159.254207.0.159.2558,190
6207.0.160.0/19207.0.160.1 to 207.0.191.254207.0.191.2558,190
7207.0.192.0/19207.0.192.1 to 207.0.223.254207.0.223.2558,190
8207.0.224.0/19207.0.224.1 to 207.0.255.254207.0.255.2558,190
9207.1.0.0/19207.1.0.1 to 207.1.31.254207.1.31.2558,190
10207.1.32.0/19207.1.32.1 to 207.1.63.254207.1.63.2558,190
11207.1.64.0/19207.1.64.1 to 207.1.95.254207.1.95.2558,190
12207.1.96.0/19207.1.96.1 to 207.1.127.254207.1.127.2558,190
13207.1.128.0/19207.1.128.1 to 207.1.159.254207.1.159.2558,190
14207.1.160.0/19207.1.160.1 to 207.1.191.254207.1.191.2558,190
15207.1.192.0/19207.1.192.1 to 207.1.223.254207.1.223.2558,190
16207.1.224.0/19207.1.224.1 to 207.1.255.254207.1.255.2558,190
17207.2.0.0/19207.2.0.1 to 207.2.31.254207.2.31.2558,190
18207.2.32.0/19207.2.32.1 to 207.2.63.254207.2.63.2558,190
19207.2.64.0/19207.2.64.1 to 207.2.95.254207.2.95.2558,190
20207.2.96.0/19207.2.96.1 to 207.2.127.254207.2.127.2558,190
21207.2.128.0/19207.2.128.1 to 207.2.159.254207.2.159.2558,190
22207.2.160.0/19207.2.160.1 to 207.2.191.254207.2.191.2558,190
23207.2.192.0/19207.2.192.1 to 207.2.223.254207.2.223.2558,190
24207.2.224.0/19207.2.224.1 to 207.2.255.254207.2.255.2558,190
25207.3.0.0/19207.3.0.1 to 207.3.31.254207.3.31.2558,190
26207.3.32.0/19207.3.32.1 to 207.3.63.254207.3.63.2558,190
27207.3.64.0/19207.3.64.1 to 207.3.95.254207.3.95.2558,190
28207.3.96.0/19207.3.96.1 to 207.3.127.254207.3.127.2558,190
29207.3.128.0/19207.3.128.1 to 207.3.159.254207.3.159.2558,190
30207.3.160.0/19207.3.160.1 to 207.3.191.254207.3.191.2558,190
31207.3.192.0/19207.3.192.1 to 207.3.223.254207.3.223.2558,190
32207.3.224.0/19207.3.224.1 to 207.3.255.254207.3.255.2558,190
33207.4.0.0/19207.4.0.1 to 207.4.31.254207.4.31.2558,190
34207.4.32.0/19207.4.32.1 to 207.4.63.254207.4.63.2558,190
35207.4.64.0/19207.4.64.1 to 207.4.95.254207.4.95.2558,190
36207.4.96.0/19207.4.96.1 to 207.4.127.254207.4.127.2558,190
37207.4.128.0/19207.4.128.1 to 207.4.159.254207.4.159.2558,190
38207.4.160.0/19207.4.160.1 to 207.4.191.254207.4.191.2558,190
39207.4.192.0/19207.4.192.1 to 207.4.223.254207.4.223.2558,190
40207.4.224.0/19207.4.224.1 to 207.4.255.254207.4.255.2558,190
41207.5.0.0/19207.5.0.1 to 207.5.31.254207.5.31.2558,190
42207.5.32.0/19207.5.32.1 to 207.5.63.254207.5.63.2558,190
43207.5.64.0/19207.5.64.1 to 207.5.95.254207.5.95.2558,190
44207.5.96.0/19207.5.96.1 to 207.5.127.254207.5.127.2558,190
45207.5.128.0/19207.5.128.1 to 207.5.159.254207.5.159.2558,190
46207.5.160.0/19207.5.160.1 to 207.5.191.254207.5.191.2558,190
47207.5.192.0/19207.5.192.1 to 207.5.223.254207.5.223.2558,190
48207.5.224.0/19207.5.224.1 to 207.5.255.254207.5.255.2558,190
49207.6.0.0/19207.6.0.1 to 207.6.31.254207.6.31.2558,190
50207.6.32.0/19207.6.32.1 to 207.6.63.254207.6.63.2558,190
51207.6.64.0/19207.6.64.1 to 207.6.95.254207.6.95.2558,190
52207.6.96.0/19207.6.96.1 to 207.6.127.254207.6.127.2558,190
53207.6.128.0/19207.6.128.1 to 207.6.159.254207.6.159.2558,190
54207.6.160.0/19207.6.160.1 to 207.6.191.254207.6.191.2558,190
55207.6.192.0/19207.6.192.1 to 207.6.223.254207.6.223.2558,190
56207.6.224.0/19207.6.224.1 to 207.6.255.254207.6.255.2558,190
57207.7.0.0/19207.7.0.1 to 207.7.31.254207.7.31.2558,190
58207.7.32.0/19207.7.32.1 to 207.7.63.254207.7.63.2558,190
59207.7.64.0/19207.7.64.1 to 207.7.95.254207.7.95.2558,190
60207.7.96.0/19207.7.96.1 to 207.7.127.254207.7.127.2558,190
61207.7.128.0/19207.7.128.1 to 207.7.159.254207.7.159.2558,190
62207.7.160.0/19207.7.160.1 to 207.7.191.254207.7.191.2558,190
63207.7.192.0/19207.7.192.1 to 207.7.223.254207.7.223.2558,190
64207.7.224.0/19207.7.224.1 to 207.7.255.254207.7.255.2558,190
65207.8.0.0/19207.8.0.1 to 207.8.31.254207.8.31.2558,190
66207.8.32.0/19207.8.32.1 to 207.8.63.254207.8.63.2558,190
67207.8.64.0/19207.8.64.1 to 207.8.95.254207.8.95.2558,190
68207.8.96.0/19207.8.96.1 to 207.8.127.254207.8.127.2558,190
69207.8.128.0/19207.8.128.1 to 207.8.159.254207.8.159.2558,190
70207.8.160.0/19207.8.160.1 to 207.8.191.254207.8.191.2558,190
71207.8.192.0/19207.8.192.1 to 207.8.223.254207.8.223.2558,190
72207.8.224.0/19207.8.224.1 to 207.8.255.254207.8.255.2558,190
73207.9.0.0/19207.9.0.1 to 207.9.31.254207.9.31.2558,190
74207.9.32.0/19207.9.32.1 to 207.9.63.254207.9.63.2558,190
75207.9.64.0/19207.9.64.1 to 207.9.95.254207.9.95.2558,190
76207.9.96.0/19207.9.96.1 to 207.9.127.254207.9.127.2558,190
77207.9.128.0/19207.9.128.1 to 207.9.159.254207.9.159.2558,190
78207.9.160.0/19207.9.160.1 to 207.9.191.254207.9.191.2558,190
79207.9.192.0/19207.9.192.1 to 207.9.223.254207.9.223.2558,190
80207.9.224.0/19207.9.224.1 to 207.9.255.254207.9.255.2558,190
81207.10.0.0/19207.10.0.1 to 207.10.31.254207.10.31.2558,190
82207.10.32.0/19207.10.32.1 to 207.10.63.254207.10.63.2558,190
83207.10.64.0/19207.10.64.1 to 207.10.95.254207.10.95.2558,190
84207.10.96.0/19207.10.96.1 to 207.10.127.254207.10.127.2558,190
85207.10.128.0/19207.10.128.1 to 207.10.159.254207.10.159.2558,190
86207.10.160.0/19207.10.160.1 to 207.10.191.254207.10.191.2558,190
87207.10.192.0/19207.10.192.1 to 207.10.223.254207.10.223.2558,190
88207.10.224.0/19207.10.224.1 to 207.10.255.254207.10.255.2558,190
89207.11.0.0/19207.11.0.1 to 207.11.31.254207.11.31.2558,190
90207.11.32.0/19207.11.32.1 to 207.11.63.254207.11.63.2558,190
91207.11.64.0/19207.11.64.1 to 207.11.95.254207.11.95.2558,190
92207.11.96.0/19207.11.96.1 to 207.11.127.254207.11.127.2558,190
93207.11.128.0/19207.11.128.1 to 207.11.159.254207.11.159.2558,190
94207.11.160.0/19207.11.160.1 to 207.11.191.254207.11.191.2558,190
95207.11.192.0/19207.11.192.1 to 207.11.223.254207.11.223.2558,190
96207.11.224.0/19207.11.224.1 to 207.11.255.254207.11.255.2558,190
97207.12.0.0/19207.12.0.1 to 207.12.31.254207.12.31.2558,190
98207.12.32.0/19207.12.32.1 to 207.12.63.254207.12.63.2558,190
99207.12.64.0/19207.12.64.1 to 207.12.95.254207.12.95.2558,190
100207.12.96.0/19207.12.96.1 to 207.12.127.254207.12.127.2558,190
101207.12.128.0/19207.12.128.1 to 207.12.159.254207.12.159.2558,190
102207.12.160.0/19207.12.160.1 to 207.12.191.254207.12.191.2558,190
103207.12.192.0/19207.12.192.1 to 207.12.223.254207.12.223.2558,190
104207.12.224.0/19207.12.224.1 to 207.12.255.254207.12.255.2558,190
105207.13.0.0/19207.13.0.1 to 207.13.31.254207.13.31.2558,190
106207.13.32.0/19207.13.32.1 to 207.13.63.254207.13.63.2558,190
107207.13.64.0/19207.13.64.1 to 207.13.95.254207.13.95.2558,190
108207.13.96.0/19207.13.96.1 to 207.13.127.254207.13.127.2558,190
109207.13.128.0/19207.13.128.1 to 207.13.159.254207.13.159.2558,190
110207.13.160.0/19207.13.160.1 to 207.13.191.254207.13.191.2558,190
111207.13.192.0/19207.13.192.1 to 207.13.223.254207.13.223.2558,190
112207.13.224.0/19207.13.224.1 to 207.13.255.254207.13.255.2558,190
113207.14.0.0/19207.14.0.1 to 207.14.31.254207.14.31.2558,190
114207.14.32.0/19207.14.32.1 to 207.14.63.254207.14.63.2558,190
115207.14.64.0/19207.14.64.1 to 207.14.95.254207.14.95.2558,190
116207.14.96.0/19207.14.96.1 to 207.14.127.254207.14.127.2558,190
117207.14.128.0/19207.14.128.1 to 207.14.159.254207.14.159.2558,190
118207.14.160.0/19207.14.160.1 to 207.14.191.254207.14.191.2558,190
119207.14.192.0/19207.14.192.1 to 207.14.223.254207.14.223.2558,190
120207.14.224.0/19207.14.224.1 to 207.14.255.254207.14.255.2558,190
121207.15.0.0/19207.15.0.1 to 207.15.31.254207.15.31.2558,190
122207.15.32.0/19207.15.32.1 to 207.15.63.254207.15.63.2558,190
123207.15.64.0/19207.15.64.1 to 207.15.95.254207.15.95.2558,190
124207.15.96.0/19207.15.96.1 to 207.15.127.254207.15.127.2558,190
125207.15.128.0/19207.15.128.1 to 207.15.159.254207.15.159.2558,190
126207.15.160.0/19207.15.160.1 to 207.15.191.254207.15.191.2558,190
127207.15.192.0/19207.15.192.1 to 207.15.223.254207.15.223.2558,190
128207.15.224.0/19207.15.224.1 to 207.15.255.254207.15.255.2558,190
129207.16.0.0/19207.16.0.1 to 207.16.31.254207.16.31.2558,190
130207.16.32.0/19207.16.32.1 to 207.16.63.254207.16.63.2558,190
131207.16.64.0/19207.16.64.1 to 207.16.95.254207.16.95.2558,190
132207.16.96.0/19207.16.96.1 to 207.16.127.254207.16.127.2558,190
133207.16.128.0/19207.16.128.1 to 207.16.159.254207.16.159.2558,190
134207.16.160.0/19207.16.160.1 to 207.16.191.254207.16.191.2558,190
135207.16.192.0/19207.16.192.1 to 207.16.223.254207.16.223.2558,190
136207.16.224.0/19207.16.224.1 to 207.16.255.254207.16.255.2558,190
137207.17.0.0/19207.17.0.1 to 207.17.31.254207.17.31.2558,190
138207.17.32.0/19207.17.32.1 to 207.17.63.254207.17.63.2558,190
139207.17.64.0/19207.17.64.1 to 207.17.95.254207.17.95.2558,190
140207.17.96.0/19207.17.96.1 to 207.17.127.254207.17.127.2558,190
141207.17.128.0/19207.17.128.1 to 207.17.159.254207.17.159.2558,190
142207.17.160.0/19207.17.160.1 to 207.17.191.254207.17.191.2558,190
143207.17.192.0/19207.17.192.1 to 207.17.223.254207.17.223.2558,190
144207.17.224.0/19207.17.224.1 to 207.17.255.254207.17.255.2558,190
145207.18.0.0/19207.18.0.1 to 207.18.31.254207.18.31.2558,190
146207.18.32.0/19207.18.32.1 to 207.18.63.254207.18.63.2558,190
147207.18.64.0/19207.18.64.1 to 207.18.95.254207.18.95.2558,190
148207.18.96.0/19207.18.96.1 to 207.18.127.254207.18.127.2558,190
149207.18.128.0/19207.18.128.1 to 207.18.159.254207.18.159.2558,190
150207.18.160.0/19207.18.160.1 to 207.18.191.254207.18.191.2558,190
151207.18.192.0/19207.18.192.1 to 207.18.223.254207.18.223.2558,190
152207.18.224.0/19207.18.224.1 to 207.18.255.254207.18.255.2558,190
153207.19.0.0/19207.19.0.1 to 207.19.31.254207.19.31.2558,190
154207.19.32.0/19207.19.32.1 to 207.19.63.254207.19.63.2558,190
155207.19.64.0/19207.19.64.1 to 207.19.95.254207.19.95.2558,190
156207.19.96.0/19207.19.96.1 to 207.19.127.254207.19.127.2558,190
157207.19.128.0/19207.19.128.1 to 207.19.159.254207.19.159.2558,190
158207.19.160.0/19207.19.160.1 to 207.19.191.254207.19.191.2558,190
159207.19.192.0/19207.19.192.1 to 207.19.223.254207.19.223.2558,190
160207.19.224.0/19207.19.224.1 to 207.19.255.254207.19.255.2558,190
161207.20.0.0/19207.20.0.1 to 207.20.31.254207.20.31.2558,190
162207.20.32.0/19207.20.32.1 to 207.20.63.254207.20.63.2558,190
163207.20.64.0/19207.20.64.1 to 207.20.95.254207.20.95.2558,190
164207.20.96.0/19207.20.96.1 to 207.20.127.254207.20.127.2558,190
165207.20.128.0/19207.20.128.1 to 207.20.159.254207.20.159.2558,190
166207.20.160.0/19207.20.160.1 to 207.20.191.254207.20.191.2558,190
167207.20.192.0/19207.20.192.1 to 207.20.223.254207.20.223.2558,190
168207.20.224.0/19207.20.224.1 to 207.20.255.254207.20.255.2558,190
169207.21.0.0/19207.21.0.1 to 207.21.31.254207.21.31.2558,190
170207.21.32.0/19207.21.32.1 to 207.21.63.254207.21.63.2558,190
171207.21.64.0/19207.21.64.1 to 207.21.95.254207.21.95.2558,190
172207.21.96.0/19207.21.96.1 to 207.21.127.254207.21.127.2558,190
173207.21.128.0/19207.21.128.1 to 207.21.159.254207.21.159.2558,190
174207.21.160.0/19207.21.160.1 to 207.21.191.254207.21.191.2558,190
175207.21.192.0/19207.21.192.1 to 207.21.223.254207.21.223.2558,190
176207.21.224.0/19207.21.224.1 to 207.21.255.254207.21.255.2558,190
177207.22.0.0/19207.22.0.1 to 207.22.31.254207.22.31.2558,190
178207.22.32.0/19207.22.32.1 to 207.22.63.254207.22.63.2558,190
179207.22.64.0/19207.22.64.1 to 207.22.95.254207.22.95.2558,190
180207.22.96.0/19207.22.96.1 to 207.22.127.254207.22.127.2558,190
181207.22.128.0/19207.22.128.1 to 207.22.159.254207.22.159.2558,190
182207.22.160.0/19207.22.160.1 to 207.22.191.254207.22.191.2558,190
183207.22.192.0/19207.22.192.1 to 207.22.223.254207.22.223.2558,190
184207.22.224.0/19207.22.224.1 to 207.22.255.254207.22.255.2558,190
185207.23.0.0/19207.23.0.1 to 207.23.31.254207.23.31.2558,190
186207.23.32.0/19207.23.32.1 to 207.23.63.254207.23.63.2558,190
187207.23.64.0/19207.23.64.1 to 207.23.95.254207.23.95.2558,190
188207.23.96.0/19207.23.96.1 to 207.23.127.254207.23.127.2558,190
189207.23.128.0/19207.23.128.1 to 207.23.159.254207.23.159.2558,190
190207.23.160.0/19207.23.160.1 to 207.23.191.254207.23.191.2558,190
191207.23.192.0/19207.23.192.1 to 207.23.223.254207.23.223.2558,190
192207.23.224.0/19207.23.224.1 to 207.23.255.254207.23.255.2558,190
193207.24.0.0/19207.24.0.1 to 207.24.31.254207.24.31.2558,190
194207.24.32.0/19207.24.32.1 to 207.24.63.254207.24.63.2558,190
195207.24.64.0/19207.24.64.1 to 207.24.95.254207.24.95.2558,190
196207.24.96.0/19207.24.96.1 to 207.24.127.254207.24.127.2558,190
197207.24.128.0/19207.24.128.1 to 207.24.159.254207.24.159.2558,190
198207.24.160.0/19207.24.160.1 to 207.24.191.254207.24.191.2558,190
199207.24.192.0/19207.24.192.1 to 207.24.223.254207.24.223.2558,190
200207.24.224.0/19207.24.224.1 to 207.24.255.254207.24.255.2558,190
201207.25.0.0/19207.25.0.1 to 207.25.31.254207.25.31.2558,190
202207.25.32.0/19207.25.32.1 to 207.25.63.254207.25.63.2558,190
203207.25.64.0/19207.25.64.1 to 207.25.95.254207.25.95.2558,190
204207.25.96.0/19207.25.96.1 to 207.25.127.254207.25.127.2558,190
205207.25.128.0/19207.25.128.1 to 207.25.159.254207.25.159.2558,190
206207.25.160.0/19207.25.160.1 to 207.25.191.254207.25.191.2558,190
207207.25.192.0/19207.25.192.1 to 207.25.223.254207.25.223.2558,190
208207.25.224.0/19207.25.224.1 to 207.25.255.254207.25.255.2558,190
209207.26.0.0/19207.26.0.1 to 207.26.31.254207.26.31.2558,190
210207.26.32.0/19207.26.32.1 to 207.26.63.254207.26.63.2558,190
211207.26.64.0/19207.26.64.1 to 207.26.95.254207.26.95.2558,190
212207.26.96.0/19207.26.96.1 to 207.26.127.254207.26.127.2558,190
213207.26.128.0/19207.26.128.1 to 207.26.159.254207.26.159.2558,190
214207.26.160.0/19207.26.160.1 to 207.26.191.254207.26.191.2558,190
215207.26.192.0/19207.26.192.1 to 207.26.223.254207.26.223.2558,190
216207.26.224.0/19207.26.224.1 to 207.26.255.254207.26.255.2558,190
217207.27.0.0/19207.27.0.1 to 207.27.31.254207.27.31.2558,190
218207.27.32.0/19207.27.32.1 to 207.27.63.254207.27.63.2558,190
219207.27.64.0/19207.27.64.1 to 207.27.95.254207.27.95.2558,190
220207.27.96.0/19207.27.96.1 to 207.27.127.254207.27.127.2558,190
221207.27.128.0/19207.27.128.1 to 207.27.159.254207.27.159.2558,190
222207.27.160.0/19207.27.160.1 to 207.27.191.254207.27.191.2558,190
223207.27.192.0/19207.27.192.1 to 207.27.223.254207.27.223.2558,190
224207.27.224.0/19207.27.224.1 to 207.27.255.254207.27.255.2558,190
225207.28.0.0/19207.28.0.1 to 207.28.31.254207.28.31.2558,190
226207.28.32.0/19207.28.32.1 to 207.28.63.254207.28.63.2558,190
227207.28.64.0/19207.28.64.1 to 207.28.95.254207.28.95.2558,190
228207.28.96.0/19207.28.96.1 to 207.28.127.254207.28.127.2558,190
229207.28.128.0/19207.28.128.1 to 207.28.159.254207.28.159.2558,190
230207.28.160.0/19207.28.160.1 to 207.28.191.254207.28.191.2558,190
231207.28.192.0/19207.28.192.1 to 207.28.223.254207.28.223.2558,190
232207.28.224.0/19207.28.224.1 to 207.28.255.254207.28.255.2558,190
233207.29.0.0/19207.29.0.1 to 207.29.31.254207.29.31.2558,190
234207.29.32.0/19207.29.32.1 to 207.29.63.254207.29.63.2558,190
235207.29.64.0/19207.29.64.1 to 207.29.95.254207.29.95.2558,190
236207.29.96.0/19207.29.96.1 to 207.29.127.254207.29.127.2558,190
237207.29.128.0/19207.29.128.1 to 207.29.159.254207.29.159.2558,190
238207.29.160.0/19207.29.160.1 to 207.29.191.254207.29.191.2558,190
239207.29.192.0/19207.29.192.1 to 207.29.223.254207.29.223.2558,190
240207.29.224.0/19207.29.224.1 to 207.29.255.254207.29.255.2558,190
241207.30.0.0/19207.30.0.1 to 207.30.31.254207.30.31.2558,190
242207.30.32.0/19207.30.32.1 to 207.30.63.254207.30.63.2558,190
243207.30.64.0/19207.30.64.1 to 207.30.95.254207.30.95.2558,190
244207.30.96.0/19207.30.96.1 to 207.30.127.254207.30.127.2558,190
245207.30.128.0/19207.30.128.1 to 207.30.159.254207.30.159.2558,190
246207.30.160.0/19207.30.160.1 to 207.30.191.254207.30.191.2558,190
247207.30.192.0/19207.30.192.1 to 207.30.223.254207.30.223.2558,190
248207.30.224.0/19207.30.224.1 to 207.30.255.254207.30.255.2558,190
249207.31.0.0/19207.31.0.1 to 207.31.31.254207.31.31.2558,190
250207.31.32.0/19207.31.32.1 to 207.31.63.254207.31.63.2558,190
251207.31.64.0/19207.31.64.1 to 207.31.95.254207.31.95.2558,190
252207.31.96.0/19207.31.96.1 to 207.31.127.254207.31.127.2558,190
253207.31.128.0/19207.31.128.1 to 207.31.159.254207.31.159.2558,190
254207.31.160.0/19207.31.160.1 to 207.31.191.254207.31.191.2558,190
255207.31.192.0/19207.31.192.1 to 207.31.223.254207.31.223.2558,190
256207.31.224.0/19207.31.224.1 to 207.31.255.254207.31.255.2558,190

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.