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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.

Network247.0.0.0/10
Usable hosts4,194,302
Subnet mask255.192.0.0
Addresses4,194,304
Network address
247.0.0.0
Broadcast address
247.63.255.255
First usable
247.0.0.1
Last usable
247.63.255.254
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
Reserved 240.0.0.0/4
Future use; not usable on most systems
Old class
E (reserved)
As numbers
Hex F7000000 · Integer 4143972352 to 4148166655
Reverse DNS zones
0.247.in-addr.arpa
1.247.in-addr.arpa
2.247.in-addr.arpa
3.247.in-addr.arpa
4.247.in-addr.arpa
5.247.in-addr.arpa
6.247.in-addr.arpa
7.247.in-addr.arpa
8.247.in-addr.arpa
9.247.in-addr.arpa
10.247.in-addr.arpa
11.247.in-addr.arpa
12.247.in-addr.arpa
13.247.in-addr.arpa
14.247.in-addr.arpa
15.247.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
Address11110111.00000000.00000000.00000000247.0.0.0
Subnet mask11111111.11000000.00000000.00000000255.192.0.0
Network11110111.00000000.00000000.00000000247.0.0.0
Broadcast11110111.00111111.11111111.11111111247.63.255.255
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)

247.0.0.0/10 makes 512 subnets of /19; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1247.0.0.0/19247.0.0.1 to 247.0.31.254247.0.31.2558,190
2247.0.32.0/19247.0.32.1 to 247.0.63.254247.0.63.2558,190
3247.0.64.0/19247.0.64.1 to 247.0.95.254247.0.95.2558,190
4247.0.96.0/19247.0.96.1 to 247.0.127.254247.0.127.2558,190
5247.0.128.0/19247.0.128.1 to 247.0.159.254247.0.159.2558,190
6247.0.160.0/19247.0.160.1 to 247.0.191.254247.0.191.2558,190
7247.0.192.0/19247.0.192.1 to 247.0.223.254247.0.223.2558,190
8247.0.224.0/19247.0.224.1 to 247.0.255.254247.0.255.2558,190
9247.1.0.0/19247.1.0.1 to 247.1.31.254247.1.31.2558,190
10247.1.32.0/19247.1.32.1 to 247.1.63.254247.1.63.2558,190
11247.1.64.0/19247.1.64.1 to 247.1.95.254247.1.95.2558,190
12247.1.96.0/19247.1.96.1 to 247.1.127.254247.1.127.2558,190
13247.1.128.0/19247.1.128.1 to 247.1.159.254247.1.159.2558,190
14247.1.160.0/19247.1.160.1 to 247.1.191.254247.1.191.2558,190
15247.1.192.0/19247.1.192.1 to 247.1.223.254247.1.223.2558,190
16247.1.224.0/19247.1.224.1 to 247.1.255.254247.1.255.2558,190
17247.2.0.0/19247.2.0.1 to 247.2.31.254247.2.31.2558,190
18247.2.32.0/19247.2.32.1 to 247.2.63.254247.2.63.2558,190
19247.2.64.0/19247.2.64.1 to 247.2.95.254247.2.95.2558,190
20247.2.96.0/19247.2.96.1 to 247.2.127.254247.2.127.2558,190
21247.2.128.0/19247.2.128.1 to 247.2.159.254247.2.159.2558,190
22247.2.160.0/19247.2.160.1 to 247.2.191.254247.2.191.2558,190
23247.2.192.0/19247.2.192.1 to 247.2.223.254247.2.223.2558,190
24247.2.224.0/19247.2.224.1 to 247.2.255.254247.2.255.2558,190
25247.3.0.0/19247.3.0.1 to 247.3.31.254247.3.31.2558,190
26247.3.32.0/19247.3.32.1 to 247.3.63.254247.3.63.2558,190
27247.3.64.0/19247.3.64.1 to 247.3.95.254247.3.95.2558,190
28247.3.96.0/19247.3.96.1 to 247.3.127.254247.3.127.2558,190
29247.3.128.0/19247.3.128.1 to 247.3.159.254247.3.159.2558,190
30247.3.160.0/19247.3.160.1 to 247.3.191.254247.3.191.2558,190
31247.3.192.0/19247.3.192.1 to 247.3.223.254247.3.223.2558,190
32247.3.224.0/19247.3.224.1 to 247.3.255.254247.3.255.2558,190
33247.4.0.0/19247.4.0.1 to 247.4.31.254247.4.31.2558,190
34247.4.32.0/19247.4.32.1 to 247.4.63.254247.4.63.2558,190
35247.4.64.0/19247.4.64.1 to 247.4.95.254247.4.95.2558,190
36247.4.96.0/19247.4.96.1 to 247.4.127.254247.4.127.2558,190
37247.4.128.0/19247.4.128.1 to 247.4.159.254247.4.159.2558,190
38247.4.160.0/19247.4.160.1 to 247.4.191.254247.4.191.2558,190
39247.4.192.0/19247.4.192.1 to 247.4.223.254247.4.223.2558,190
40247.4.224.0/19247.4.224.1 to 247.4.255.254247.4.255.2558,190
41247.5.0.0/19247.5.0.1 to 247.5.31.254247.5.31.2558,190
42247.5.32.0/19247.5.32.1 to 247.5.63.254247.5.63.2558,190
43247.5.64.0/19247.5.64.1 to 247.5.95.254247.5.95.2558,190
44247.5.96.0/19247.5.96.1 to 247.5.127.254247.5.127.2558,190
45247.5.128.0/19247.5.128.1 to 247.5.159.254247.5.159.2558,190
46247.5.160.0/19247.5.160.1 to 247.5.191.254247.5.191.2558,190
47247.5.192.0/19247.5.192.1 to 247.5.223.254247.5.223.2558,190
48247.5.224.0/19247.5.224.1 to 247.5.255.254247.5.255.2558,190
49247.6.0.0/19247.6.0.1 to 247.6.31.254247.6.31.2558,190
50247.6.32.0/19247.6.32.1 to 247.6.63.254247.6.63.2558,190
51247.6.64.0/19247.6.64.1 to 247.6.95.254247.6.95.2558,190
52247.6.96.0/19247.6.96.1 to 247.6.127.254247.6.127.2558,190
53247.6.128.0/19247.6.128.1 to 247.6.159.254247.6.159.2558,190
54247.6.160.0/19247.6.160.1 to 247.6.191.254247.6.191.2558,190
55247.6.192.0/19247.6.192.1 to 247.6.223.254247.6.223.2558,190
56247.6.224.0/19247.6.224.1 to 247.6.255.254247.6.255.2558,190
57247.7.0.0/19247.7.0.1 to 247.7.31.254247.7.31.2558,190
58247.7.32.0/19247.7.32.1 to 247.7.63.254247.7.63.2558,190
59247.7.64.0/19247.7.64.1 to 247.7.95.254247.7.95.2558,190
60247.7.96.0/19247.7.96.1 to 247.7.127.254247.7.127.2558,190
61247.7.128.0/19247.7.128.1 to 247.7.159.254247.7.159.2558,190
62247.7.160.0/19247.7.160.1 to 247.7.191.254247.7.191.2558,190
63247.7.192.0/19247.7.192.1 to 247.7.223.254247.7.223.2558,190
64247.7.224.0/19247.7.224.1 to 247.7.255.254247.7.255.2558,190
65247.8.0.0/19247.8.0.1 to 247.8.31.254247.8.31.2558,190
66247.8.32.0/19247.8.32.1 to 247.8.63.254247.8.63.2558,190
67247.8.64.0/19247.8.64.1 to 247.8.95.254247.8.95.2558,190
68247.8.96.0/19247.8.96.1 to 247.8.127.254247.8.127.2558,190
69247.8.128.0/19247.8.128.1 to 247.8.159.254247.8.159.2558,190
70247.8.160.0/19247.8.160.1 to 247.8.191.254247.8.191.2558,190
71247.8.192.0/19247.8.192.1 to 247.8.223.254247.8.223.2558,190
72247.8.224.0/19247.8.224.1 to 247.8.255.254247.8.255.2558,190
73247.9.0.0/19247.9.0.1 to 247.9.31.254247.9.31.2558,190
74247.9.32.0/19247.9.32.1 to 247.9.63.254247.9.63.2558,190
75247.9.64.0/19247.9.64.1 to 247.9.95.254247.9.95.2558,190
76247.9.96.0/19247.9.96.1 to 247.9.127.254247.9.127.2558,190
77247.9.128.0/19247.9.128.1 to 247.9.159.254247.9.159.2558,190
78247.9.160.0/19247.9.160.1 to 247.9.191.254247.9.191.2558,190
79247.9.192.0/19247.9.192.1 to 247.9.223.254247.9.223.2558,190
80247.9.224.0/19247.9.224.1 to 247.9.255.254247.9.255.2558,190
81247.10.0.0/19247.10.0.1 to 247.10.31.254247.10.31.2558,190
82247.10.32.0/19247.10.32.1 to 247.10.63.254247.10.63.2558,190
83247.10.64.0/19247.10.64.1 to 247.10.95.254247.10.95.2558,190
84247.10.96.0/19247.10.96.1 to 247.10.127.254247.10.127.2558,190
85247.10.128.0/19247.10.128.1 to 247.10.159.254247.10.159.2558,190
86247.10.160.0/19247.10.160.1 to 247.10.191.254247.10.191.2558,190
87247.10.192.0/19247.10.192.1 to 247.10.223.254247.10.223.2558,190
88247.10.224.0/19247.10.224.1 to 247.10.255.254247.10.255.2558,190
89247.11.0.0/19247.11.0.1 to 247.11.31.254247.11.31.2558,190
90247.11.32.0/19247.11.32.1 to 247.11.63.254247.11.63.2558,190
91247.11.64.0/19247.11.64.1 to 247.11.95.254247.11.95.2558,190
92247.11.96.0/19247.11.96.1 to 247.11.127.254247.11.127.2558,190
93247.11.128.0/19247.11.128.1 to 247.11.159.254247.11.159.2558,190
94247.11.160.0/19247.11.160.1 to 247.11.191.254247.11.191.2558,190
95247.11.192.0/19247.11.192.1 to 247.11.223.254247.11.223.2558,190
96247.11.224.0/19247.11.224.1 to 247.11.255.254247.11.255.2558,190
97247.12.0.0/19247.12.0.1 to 247.12.31.254247.12.31.2558,190
98247.12.32.0/19247.12.32.1 to 247.12.63.254247.12.63.2558,190
99247.12.64.0/19247.12.64.1 to 247.12.95.254247.12.95.2558,190
100247.12.96.0/19247.12.96.1 to 247.12.127.254247.12.127.2558,190
101247.12.128.0/19247.12.128.1 to 247.12.159.254247.12.159.2558,190
102247.12.160.0/19247.12.160.1 to 247.12.191.254247.12.191.2558,190
103247.12.192.0/19247.12.192.1 to 247.12.223.254247.12.223.2558,190
104247.12.224.0/19247.12.224.1 to 247.12.255.254247.12.255.2558,190
105247.13.0.0/19247.13.0.1 to 247.13.31.254247.13.31.2558,190
106247.13.32.0/19247.13.32.1 to 247.13.63.254247.13.63.2558,190
107247.13.64.0/19247.13.64.1 to 247.13.95.254247.13.95.2558,190
108247.13.96.0/19247.13.96.1 to 247.13.127.254247.13.127.2558,190
109247.13.128.0/19247.13.128.1 to 247.13.159.254247.13.159.2558,190
110247.13.160.0/19247.13.160.1 to 247.13.191.254247.13.191.2558,190
111247.13.192.0/19247.13.192.1 to 247.13.223.254247.13.223.2558,190
112247.13.224.0/19247.13.224.1 to 247.13.255.254247.13.255.2558,190
113247.14.0.0/19247.14.0.1 to 247.14.31.254247.14.31.2558,190
114247.14.32.0/19247.14.32.1 to 247.14.63.254247.14.63.2558,190
115247.14.64.0/19247.14.64.1 to 247.14.95.254247.14.95.2558,190
116247.14.96.0/19247.14.96.1 to 247.14.127.254247.14.127.2558,190
117247.14.128.0/19247.14.128.1 to 247.14.159.254247.14.159.2558,190
118247.14.160.0/19247.14.160.1 to 247.14.191.254247.14.191.2558,190
119247.14.192.0/19247.14.192.1 to 247.14.223.254247.14.223.2558,190
120247.14.224.0/19247.14.224.1 to 247.14.255.254247.14.255.2558,190
121247.15.0.0/19247.15.0.1 to 247.15.31.254247.15.31.2558,190
122247.15.32.0/19247.15.32.1 to 247.15.63.254247.15.63.2558,190
123247.15.64.0/19247.15.64.1 to 247.15.95.254247.15.95.2558,190
124247.15.96.0/19247.15.96.1 to 247.15.127.254247.15.127.2558,190
125247.15.128.0/19247.15.128.1 to 247.15.159.254247.15.159.2558,190
126247.15.160.0/19247.15.160.1 to 247.15.191.254247.15.191.2558,190
127247.15.192.0/19247.15.192.1 to 247.15.223.254247.15.223.2558,190
128247.15.224.0/19247.15.224.1 to 247.15.255.254247.15.255.2558,190
129247.16.0.0/19247.16.0.1 to 247.16.31.254247.16.31.2558,190
130247.16.32.0/19247.16.32.1 to 247.16.63.254247.16.63.2558,190
131247.16.64.0/19247.16.64.1 to 247.16.95.254247.16.95.2558,190
132247.16.96.0/19247.16.96.1 to 247.16.127.254247.16.127.2558,190
133247.16.128.0/19247.16.128.1 to 247.16.159.254247.16.159.2558,190
134247.16.160.0/19247.16.160.1 to 247.16.191.254247.16.191.2558,190
135247.16.192.0/19247.16.192.1 to 247.16.223.254247.16.223.2558,190
136247.16.224.0/19247.16.224.1 to 247.16.255.254247.16.255.2558,190
137247.17.0.0/19247.17.0.1 to 247.17.31.254247.17.31.2558,190
138247.17.32.0/19247.17.32.1 to 247.17.63.254247.17.63.2558,190
139247.17.64.0/19247.17.64.1 to 247.17.95.254247.17.95.2558,190
140247.17.96.0/19247.17.96.1 to 247.17.127.254247.17.127.2558,190
141247.17.128.0/19247.17.128.1 to 247.17.159.254247.17.159.2558,190
142247.17.160.0/19247.17.160.1 to 247.17.191.254247.17.191.2558,190
143247.17.192.0/19247.17.192.1 to 247.17.223.254247.17.223.2558,190
144247.17.224.0/19247.17.224.1 to 247.17.255.254247.17.255.2558,190
145247.18.0.0/19247.18.0.1 to 247.18.31.254247.18.31.2558,190
146247.18.32.0/19247.18.32.1 to 247.18.63.254247.18.63.2558,190
147247.18.64.0/19247.18.64.1 to 247.18.95.254247.18.95.2558,190
148247.18.96.0/19247.18.96.1 to 247.18.127.254247.18.127.2558,190
149247.18.128.0/19247.18.128.1 to 247.18.159.254247.18.159.2558,190
150247.18.160.0/19247.18.160.1 to 247.18.191.254247.18.191.2558,190
151247.18.192.0/19247.18.192.1 to 247.18.223.254247.18.223.2558,190
152247.18.224.0/19247.18.224.1 to 247.18.255.254247.18.255.2558,190
153247.19.0.0/19247.19.0.1 to 247.19.31.254247.19.31.2558,190
154247.19.32.0/19247.19.32.1 to 247.19.63.254247.19.63.2558,190
155247.19.64.0/19247.19.64.1 to 247.19.95.254247.19.95.2558,190
156247.19.96.0/19247.19.96.1 to 247.19.127.254247.19.127.2558,190
157247.19.128.0/19247.19.128.1 to 247.19.159.254247.19.159.2558,190
158247.19.160.0/19247.19.160.1 to 247.19.191.254247.19.191.2558,190
159247.19.192.0/19247.19.192.1 to 247.19.223.254247.19.223.2558,190
160247.19.224.0/19247.19.224.1 to 247.19.255.254247.19.255.2558,190
161247.20.0.0/19247.20.0.1 to 247.20.31.254247.20.31.2558,190
162247.20.32.0/19247.20.32.1 to 247.20.63.254247.20.63.2558,190
163247.20.64.0/19247.20.64.1 to 247.20.95.254247.20.95.2558,190
164247.20.96.0/19247.20.96.1 to 247.20.127.254247.20.127.2558,190
165247.20.128.0/19247.20.128.1 to 247.20.159.254247.20.159.2558,190
166247.20.160.0/19247.20.160.1 to 247.20.191.254247.20.191.2558,190
167247.20.192.0/19247.20.192.1 to 247.20.223.254247.20.223.2558,190
168247.20.224.0/19247.20.224.1 to 247.20.255.254247.20.255.2558,190
169247.21.0.0/19247.21.0.1 to 247.21.31.254247.21.31.2558,190
170247.21.32.0/19247.21.32.1 to 247.21.63.254247.21.63.2558,190
171247.21.64.0/19247.21.64.1 to 247.21.95.254247.21.95.2558,190
172247.21.96.0/19247.21.96.1 to 247.21.127.254247.21.127.2558,190
173247.21.128.0/19247.21.128.1 to 247.21.159.254247.21.159.2558,190
174247.21.160.0/19247.21.160.1 to 247.21.191.254247.21.191.2558,190
175247.21.192.0/19247.21.192.1 to 247.21.223.254247.21.223.2558,190
176247.21.224.0/19247.21.224.1 to 247.21.255.254247.21.255.2558,190
177247.22.0.0/19247.22.0.1 to 247.22.31.254247.22.31.2558,190
178247.22.32.0/19247.22.32.1 to 247.22.63.254247.22.63.2558,190
179247.22.64.0/19247.22.64.1 to 247.22.95.254247.22.95.2558,190
180247.22.96.0/19247.22.96.1 to 247.22.127.254247.22.127.2558,190
181247.22.128.0/19247.22.128.1 to 247.22.159.254247.22.159.2558,190
182247.22.160.0/19247.22.160.1 to 247.22.191.254247.22.191.2558,190
183247.22.192.0/19247.22.192.1 to 247.22.223.254247.22.223.2558,190
184247.22.224.0/19247.22.224.1 to 247.22.255.254247.22.255.2558,190
185247.23.0.0/19247.23.0.1 to 247.23.31.254247.23.31.2558,190
186247.23.32.0/19247.23.32.1 to 247.23.63.254247.23.63.2558,190
187247.23.64.0/19247.23.64.1 to 247.23.95.254247.23.95.2558,190
188247.23.96.0/19247.23.96.1 to 247.23.127.254247.23.127.2558,190
189247.23.128.0/19247.23.128.1 to 247.23.159.254247.23.159.2558,190
190247.23.160.0/19247.23.160.1 to 247.23.191.254247.23.191.2558,190
191247.23.192.0/19247.23.192.1 to 247.23.223.254247.23.223.2558,190
192247.23.224.0/19247.23.224.1 to 247.23.255.254247.23.255.2558,190
193247.24.0.0/19247.24.0.1 to 247.24.31.254247.24.31.2558,190
194247.24.32.0/19247.24.32.1 to 247.24.63.254247.24.63.2558,190
195247.24.64.0/19247.24.64.1 to 247.24.95.254247.24.95.2558,190
196247.24.96.0/19247.24.96.1 to 247.24.127.254247.24.127.2558,190
197247.24.128.0/19247.24.128.1 to 247.24.159.254247.24.159.2558,190
198247.24.160.0/19247.24.160.1 to 247.24.191.254247.24.191.2558,190
199247.24.192.0/19247.24.192.1 to 247.24.223.254247.24.223.2558,190
200247.24.224.0/19247.24.224.1 to 247.24.255.254247.24.255.2558,190
201247.25.0.0/19247.25.0.1 to 247.25.31.254247.25.31.2558,190
202247.25.32.0/19247.25.32.1 to 247.25.63.254247.25.63.2558,190
203247.25.64.0/19247.25.64.1 to 247.25.95.254247.25.95.2558,190
204247.25.96.0/19247.25.96.1 to 247.25.127.254247.25.127.2558,190
205247.25.128.0/19247.25.128.1 to 247.25.159.254247.25.159.2558,190
206247.25.160.0/19247.25.160.1 to 247.25.191.254247.25.191.2558,190
207247.25.192.0/19247.25.192.1 to 247.25.223.254247.25.223.2558,190
208247.25.224.0/19247.25.224.1 to 247.25.255.254247.25.255.2558,190
209247.26.0.0/19247.26.0.1 to 247.26.31.254247.26.31.2558,190
210247.26.32.0/19247.26.32.1 to 247.26.63.254247.26.63.2558,190
211247.26.64.0/19247.26.64.1 to 247.26.95.254247.26.95.2558,190
212247.26.96.0/19247.26.96.1 to 247.26.127.254247.26.127.2558,190
213247.26.128.0/19247.26.128.1 to 247.26.159.254247.26.159.2558,190
214247.26.160.0/19247.26.160.1 to 247.26.191.254247.26.191.2558,190
215247.26.192.0/19247.26.192.1 to 247.26.223.254247.26.223.2558,190
216247.26.224.0/19247.26.224.1 to 247.26.255.254247.26.255.2558,190
217247.27.0.0/19247.27.0.1 to 247.27.31.254247.27.31.2558,190
218247.27.32.0/19247.27.32.1 to 247.27.63.254247.27.63.2558,190
219247.27.64.0/19247.27.64.1 to 247.27.95.254247.27.95.2558,190
220247.27.96.0/19247.27.96.1 to 247.27.127.254247.27.127.2558,190
221247.27.128.0/19247.27.128.1 to 247.27.159.254247.27.159.2558,190
222247.27.160.0/19247.27.160.1 to 247.27.191.254247.27.191.2558,190
223247.27.192.0/19247.27.192.1 to 247.27.223.254247.27.223.2558,190
224247.27.224.0/19247.27.224.1 to 247.27.255.254247.27.255.2558,190
225247.28.0.0/19247.28.0.1 to 247.28.31.254247.28.31.2558,190
226247.28.32.0/19247.28.32.1 to 247.28.63.254247.28.63.2558,190
227247.28.64.0/19247.28.64.1 to 247.28.95.254247.28.95.2558,190
228247.28.96.0/19247.28.96.1 to 247.28.127.254247.28.127.2558,190
229247.28.128.0/19247.28.128.1 to 247.28.159.254247.28.159.2558,190
230247.28.160.0/19247.28.160.1 to 247.28.191.254247.28.191.2558,190
231247.28.192.0/19247.28.192.1 to 247.28.223.254247.28.223.2558,190
232247.28.224.0/19247.28.224.1 to 247.28.255.254247.28.255.2558,190
233247.29.0.0/19247.29.0.1 to 247.29.31.254247.29.31.2558,190
234247.29.32.0/19247.29.32.1 to 247.29.63.254247.29.63.2558,190
235247.29.64.0/19247.29.64.1 to 247.29.95.254247.29.95.2558,190
236247.29.96.0/19247.29.96.1 to 247.29.127.254247.29.127.2558,190
237247.29.128.0/19247.29.128.1 to 247.29.159.254247.29.159.2558,190
238247.29.160.0/19247.29.160.1 to 247.29.191.254247.29.191.2558,190
239247.29.192.0/19247.29.192.1 to 247.29.223.254247.29.223.2558,190
240247.29.224.0/19247.29.224.1 to 247.29.255.254247.29.255.2558,190
241247.30.0.0/19247.30.0.1 to 247.30.31.254247.30.31.2558,190
242247.30.32.0/19247.30.32.1 to 247.30.63.254247.30.63.2558,190
243247.30.64.0/19247.30.64.1 to 247.30.95.254247.30.95.2558,190
244247.30.96.0/19247.30.96.1 to 247.30.127.254247.30.127.2558,190
245247.30.128.0/19247.30.128.1 to 247.30.159.254247.30.159.2558,190
246247.30.160.0/19247.30.160.1 to 247.30.191.254247.30.191.2558,190
247247.30.192.0/19247.30.192.1 to 247.30.223.254247.30.223.2558,190
248247.30.224.0/19247.30.224.1 to 247.30.255.254247.30.255.2558,190
249247.31.0.0/19247.31.0.1 to 247.31.31.254247.31.31.2558,190
250247.31.32.0/19247.31.32.1 to 247.31.63.254247.31.63.2558,190
251247.31.64.0/19247.31.64.1 to 247.31.95.254247.31.95.2558,190
252247.31.96.0/19247.31.96.1 to 247.31.127.254247.31.127.2558,190
253247.31.128.0/19247.31.128.1 to 247.31.159.254247.31.159.2558,190
254247.31.160.0/19247.31.160.1 to 247.31.191.254247.31.191.2558,190
255247.31.192.0/19247.31.192.1 to 247.31.223.254247.31.223.2558,190
256247.31.224.0/19247.31.224.1 to 247.31.255.254247.31.255.2558,190

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.