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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.

Network240.192.0.0/10
Usable hosts4,194,302
Subnet mask255.192.0.0
Addresses4,194,304
Network address
240.192.0.0
Broadcast address
240.255.255.255
First usable
240.192.0.1
Last usable
240.255.255.254
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 F0C00000 · Integer 4039114752 to 4043309055
Reverse DNS zones
192.240.in-addr.arpa
193.240.in-addr.arpa
194.240.in-addr.arpa
195.240.in-addr.arpa
196.240.in-addr.arpa
197.240.in-addr.arpa
198.240.in-addr.arpa
199.240.in-addr.arpa
200.240.in-addr.arpa
201.240.in-addr.arpa
202.240.in-addr.arpa
203.240.in-addr.arpa
204.240.in-addr.arpa
205.240.in-addr.arpa
206.240.in-addr.arpa
207.240.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
Address11110000.11000000.00000000.00000000240.192.0.0
Subnet mask11111111.11000000.00000000.00000000255.192.0.0
Network11110000.11000000.00000000.00000000240.192.0.0
Broadcast11110000.11111111.11111111.11111111240.255.255.255
Split into smaller subnets/20
/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)

240.192.0.0/10 makes 1,024 subnets of /20; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1240.192.0.0/20240.192.0.1 to 240.192.15.254240.192.15.2554,094
2240.192.16.0/20240.192.16.1 to 240.192.31.254240.192.31.2554,094
3240.192.32.0/20240.192.32.1 to 240.192.47.254240.192.47.2554,094
4240.192.48.0/20240.192.48.1 to 240.192.63.254240.192.63.2554,094
5240.192.64.0/20240.192.64.1 to 240.192.79.254240.192.79.2554,094
6240.192.80.0/20240.192.80.1 to 240.192.95.254240.192.95.2554,094
7240.192.96.0/20240.192.96.1 to 240.192.111.254240.192.111.2554,094
8240.192.112.0/20240.192.112.1 to 240.192.127.254240.192.127.2554,094
9240.192.128.0/20240.192.128.1 to 240.192.143.254240.192.143.2554,094
10240.192.144.0/20240.192.144.1 to 240.192.159.254240.192.159.2554,094
11240.192.160.0/20240.192.160.1 to 240.192.175.254240.192.175.2554,094
12240.192.176.0/20240.192.176.1 to 240.192.191.254240.192.191.2554,094
13240.192.192.0/20240.192.192.1 to 240.192.207.254240.192.207.2554,094
14240.192.208.0/20240.192.208.1 to 240.192.223.254240.192.223.2554,094
15240.192.224.0/20240.192.224.1 to 240.192.239.254240.192.239.2554,094
16240.192.240.0/20240.192.240.1 to 240.192.255.254240.192.255.2554,094
17240.193.0.0/20240.193.0.1 to 240.193.15.254240.193.15.2554,094
18240.193.16.0/20240.193.16.1 to 240.193.31.254240.193.31.2554,094
19240.193.32.0/20240.193.32.1 to 240.193.47.254240.193.47.2554,094
20240.193.48.0/20240.193.48.1 to 240.193.63.254240.193.63.2554,094
21240.193.64.0/20240.193.64.1 to 240.193.79.254240.193.79.2554,094
22240.193.80.0/20240.193.80.1 to 240.193.95.254240.193.95.2554,094
23240.193.96.0/20240.193.96.1 to 240.193.111.254240.193.111.2554,094
24240.193.112.0/20240.193.112.1 to 240.193.127.254240.193.127.2554,094
25240.193.128.0/20240.193.128.1 to 240.193.143.254240.193.143.2554,094
26240.193.144.0/20240.193.144.1 to 240.193.159.254240.193.159.2554,094
27240.193.160.0/20240.193.160.1 to 240.193.175.254240.193.175.2554,094
28240.193.176.0/20240.193.176.1 to 240.193.191.254240.193.191.2554,094
29240.193.192.0/20240.193.192.1 to 240.193.207.254240.193.207.2554,094
30240.193.208.0/20240.193.208.1 to 240.193.223.254240.193.223.2554,094
31240.193.224.0/20240.193.224.1 to 240.193.239.254240.193.239.2554,094
32240.193.240.0/20240.193.240.1 to 240.193.255.254240.193.255.2554,094
33240.194.0.0/20240.194.0.1 to 240.194.15.254240.194.15.2554,094
34240.194.16.0/20240.194.16.1 to 240.194.31.254240.194.31.2554,094
35240.194.32.0/20240.194.32.1 to 240.194.47.254240.194.47.2554,094
36240.194.48.0/20240.194.48.1 to 240.194.63.254240.194.63.2554,094
37240.194.64.0/20240.194.64.1 to 240.194.79.254240.194.79.2554,094
38240.194.80.0/20240.194.80.1 to 240.194.95.254240.194.95.2554,094
39240.194.96.0/20240.194.96.1 to 240.194.111.254240.194.111.2554,094
40240.194.112.0/20240.194.112.1 to 240.194.127.254240.194.127.2554,094
41240.194.128.0/20240.194.128.1 to 240.194.143.254240.194.143.2554,094
42240.194.144.0/20240.194.144.1 to 240.194.159.254240.194.159.2554,094
43240.194.160.0/20240.194.160.1 to 240.194.175.254240.194.175.2554,094
44240.194.176.0/20240.194.176.1 to 240.194.191.254240.194.191.2554,094
45240.194.192.0/20240.194.192.1 to 240.194.207.254240.194.207.2554,094
46240.194.208.0/20240.194.208.1 to 240.194.223.254240.194.223.2554,094
47240.194.224.0/20240.194.224.1 to 240.194.239.254240.194.239.2554,094
48240.194.240.0/20240.194.240.1 to 240.194.255.254240.194.255.2554,094
49240.195.0.0/20240.195.0.1 to 240.195.15.254240.195.15.2554,094
50240.195.16.0/20240.195.16.1 to 240.195.31.254240.195.31.2554,094
51240.195.32.0/20240.195.32.1 to 240.195.47.254240.195.47.2554,094
52240.195.48.0/20240.195.48.1 to 240.195.63.254240.195.63.2554,094
53240.195.64.0/20240.195.64.1 to 240.195.79.254240.195.79.2554,094
54240.195.80.0/20240.195.80.1 to 240.195.95.254240.195.95.2554,094
55240.195.96.0/20240.195.96.1 to 240.195.111.254240.195.111.2554,094
56240.195.112.0/20240.195.112.1 to 240.195.127.254240.195.127.2554,094
57240.195.128.0/20240.195.128.1 to 240.195.143.254240.195.143.2554,094
58240.195.144.0/20240.195.144.1 to 240.195.159.254240.195.159.2554,094
59240.195.160.0/20240.195.160.1 to 240.195.175.254240.195.175.2554,094
60240.195.176.0/20240.195.176.1 to 240.195.191.254240.195.191.2554,094
61240.195.192.0/20240.195.192.1 to 240.195.207.254240.195.207.2554,094
62240.195.208.0/20240.195.208.1 to 240.195.223.254240.195.223.2554,094
63240.195.224.0/20240.195.224.1 to 240.195.239.254240.195.239.2554,094
64240.195.240.0/20240.195.240.1 to 240.195.255.254240.195.255.2554,094
65240.196.0.0/20240.196.0.1 to 240.196.15.254240.196.15.2554,094
66240.196.16.0/20240.196.16.1 to 240.196.31.254240.196.31.2554,094
67240.196.32.0/20240.196.32.1 to 240.196.47.254240.196.47.2554,094
68240.196.48.0/20240.196.48.1 to 240.196.63.254240.196.63.2554,094
69240.196.64.0/20240.196.64.1 to 240.196.79.254240.196.79.2554,094
70240.196.80.0/20240.196.80.1 to 240.196.95.254240.196.95.2554,094
71240.196.96.0/20240.196.96.1 to 240.196.111.254240.196.111.2554,094
72240.196.112.0/20240.196.112.1 to 240.196.127.254240.196.127.2554,094
73240.196.128.0/20240.196.128.1 to 240.196.143.254240.196.143.2554,094
74240.196.144.0/20240.196.144.1 to 240.196.159.254240.196.159.2554,094
75240.196.160.0/20240.196.160.1 to 240.196.175.254240.196.175.2554,094
76240.196.176.0/20240.196.176.1 to 240.196.191.254240.196.191.2554,094
77240.196.192.0/20240.196.192.1 to 240.196.207.254240.196.207.2554,094
78240.196.208.0/20240.196.208.1 to 240.196.223.254240.196.223.2554,094
79240.196.224.0/20240.196.224.1 to 240.196.239.254240.196.239.2554,094
80240.196.240.0/20240.196.240.1 to 240.196.255.254240.196.255.2554,094
81240.197.0.0/20240.197.0.1 to 240.197.15.254240.197.15.2554,094
82240.197.16.0/20240.197.16.1 to 240.197.31.254240.197.31.2554,094
83240.197.32.0/20240.197.32.1 to 240.197.47.254240.197.47.2554,094
84240.197.48.0/20240.197.48.1 to 240.197.63.254240.197.63.2554,094
85240.197.64.0/20240.197.64.1 to 240.197.79.254240.197.79.2554,094
86240.197.80.0/20240.197.80.1 to 240.197.95.254240.197.95.2554,094
87240.197.96.0/20240.197.96.1 to 240.197.111.254240.197.111.2554,094
88240.197.112.0/20240.197.112.1 to 240.197.127.254240.197.127.2554,094
89240.197.128.0/20240.197.128.1 to 240.197.143.254240.197.143.2554,094
90240.197.144.0/20240.197.144.1 to 240.197.159.254240.197.159.2554,094
91240.197.160.0/20240.197.160.1 to 240.197.175.254240.197.175.2554,094
92240.197.176.0/20240.197.176.1 to 240.197.191.254240.197.191.2554,094
93240.197.192.0/20240.197.192.1 to 240.197.207.254240.197.207.2554,094
94240.197.208.0/20240.197.208.1 to 240.197.223.254240.197.223.2554,094
95240.197.224.0/20240.197.224.1 to 240.197.239.254240.197.239.2554,094
96240.197.240.0/20240.197.240.1 to 240.197.255.254240.197.255.2554,094
97240.198.0.0/20240.198.0.1 to 240.198.15.254240.198.15.2554,094
98240.198.16.0/20240.198.16.1 to 240.198.31.254240.198.31.2554,094
99240.198.32.0/20240.198.32.1 to 240.198.47.254240.198.47.2554,094
100240.198.48.0/20240.198.48.1 to 240.198.63.254240.198.63.2554,094
101240.198.64.0/20240.198.64.1 to 240.198.79.254240.198.79.2554,094
102240.198.80.0/20240.198.80.1 to 240.198.95.254240.198.95.2554,094
103240.198.96.0/20240.198.96.1 to 240.198.111.254240.198.111.2554,094
104240.198.112.0/20240.198.112.1 to 240.198.127.254240.198.127.2554,094
105240.198.128.0/20240.198.128.1 to 240.198.143.254240.198.143.2554,094
106240.198.144.0/20240.198.144.1 to 240.198.159.254240.198.159.2554,094
107240.198.160.0/20240.198.160.1 to 240.198.175.254240.198.175.2554,094
108240.198.176.0/20240.198.176.1 to 240.198.191.254240.198.191.2554,094
109240.198.192.0/20240.198.192.1 to 240.198.207.254240.198.207.2554,094
110240.198.208.0/20240.198.208.1 to 240.198.223.254240.198.223.2554,094
111240.198.224.0/20240.198.224.1 to 240.198.239.254240.198.239.2554,094
112240.198.240.0/20240.198.240.1 to 240.198.255.254240.198.255.2554,094
113240.199.0.0/20240.199.0.1 to 240.199.15.254240.199.15.2554,094
114240.199.16.0/20240.199.16.1 to 240.199.31.254240.199.31.2554,094
115240.199.32.0/20240.199.32.1 to 240.199.47.254240.199.47.2554,094
116240.199.48.0/20240.199.48.1 to 240.199.63.254240.199.63.2554,094
117240.199.64.0/20240.199.64.1 to 240.199.79.254240.199.79.2554,094
118240.199.80.0/20240.199.80.1 to 240.199.95.254240.199.95.2554,094
119240.199.96.0/20240.199.96.1 to 240.199.111.254240.199.111.2554,094
120240.199.112.0/20240.199.112.1 to 240.199.127.254240.199.127.2554,094
121240.199.128.0/20240.199.128.1 to 240.199.143.254240.199.143.2554,094
122240.199.144.0/20240.199.144.1 to 240.199.159.254240.199.159.2554,094
123240.199.160.0/20240.199.160.1 to 240.199.175.254240.199.175.2554,094
124240.199.176.0/20240.199.176.1 to 240.199.191.254240.199.191.2554,094
125240.199.192.0/20240.199.192.1 to 240.199.207.254240.199.207.2554,094
126240.199.208.0/20240.199.208.1 to 240.199.223.254240.199.223.2554,094
127240.199.224.0/20240.199.224.1 to 240.199.239.254240.199.239.2554,094
128240.199.240.0/20240.199.240.1 to 240.199.255.254240.199.255.2554,094
129240.200.0.0/20240.200.0.1 to 240.200.15.254240.200.15.2554,094
130240.200.16.0/20240.200.16.1 to 240.200.31.254240.200.31.2554,094
131240.200.32.0/20240.200.32.1 to 240.200.47.254240.200.47.2554,094
132240.200.48.0/20240.200.48.1 to 240.200.63.254240.200.63.2554,094
133240.200.64.0/20240.200.64.1 to 240.200.79.254240.200.79.2554,094
134240.200.80.0/20240.200.80.1 to 240.200.95.254240.200.95.2554,094
135240.200.96.0/20240.200.96.1 to 240.200.111.254240.200.111.2554,094
136240.200.112.0/20240.200.112.1 to 240.200.127.254240.200.127.2554,094
137240.200.128.0/20240.200.128.1 to 240.200.143.254240.200.143.2554,094
138240.200.144.0/20240.200.144.1 to 240.200.159.254240.200.159.2554,094
139240.200.160.0/20240.200.160.1 to 240.200.175.254240.200.175.2554,094
140240.200.176.0/20240.200.176.1 to 240.200.191.254240.200.191.2554,094
141240.200.192.0/20240.200.192.1 to 240.200.207.254240.200.207.2554,094
142240.200.208.0/20240.200.208.1 to 240.200.223.254240.200.223.2554,094
143240.200.224.0/20240.200.224.1 to 240.200.239.254240.200.239.2554,094
144240.200.240.0/20240.200.240.1 to 240.200.255.254240.200.255.2554,094
145240.201.0.0/20240.201.0.1 to 240.201.15.254240.201.15.2554,094
146240.201.16.0/20240.201.16.1 to 240.201.31.254240.201.31.2554,094
147240.201.32.0/20240.201.32.1 to 240.201.47.254240.201.47.2554,094
148240.201.48.0/20240.201.48.1 to 240.201.63.254240.201.63.2554,094
149240.201.64.0/20240.201.64.1 to 240.201.79.254240.201.79.2554,094
150240.201.80.0/20240.201.80.1 to 240.201.95.254240.201.95.2554,094
151240.201.96.0/20240.201.96.1 to 240.201.111.254240.201.111.2554,094
152240.201.112.0/20240.201.112.1 to 240.201.127.254240.201.127.2554,094
153240.201.128.0/20240.201.128.1 to 240.201.143.254240.201.143.2554,094
154240.201.144.0/20240.201.144.1 to 240.201.159.254240.201.159.2554,094
155240.201.160.0/20240.201.160.1 to 240.201.175.254240.201.175.2554,094
156240.201.176.0/20240.201.176.1 to 240.201.191.254240.201.191.2554,094
157240.201.192.0/20240.201.192.1 to 240.201.207.254240.201.207.2554,094
158240.201.208.0/20240.201.208.1 to 240.201.223.254240.201.223.2554,094
159240.201.224.0/20240.201.224.1 to 240.201.239.254240.201.239.2554,094
160240.201.240.0/20240.201.240.1 to 240.201.255.254240.201.255.2554,094
161240.202.0.0/20240.202.0.1 to 240.202.15.254240.202.15.2554,094
162240.202.16.0/20240.202.16.1 to 240.202.31.254240.202.31.2554,094
163240.202.32.0/20240.202.32.1 to 240.202.47.254240.202.47.2554,094
164240.202.48.0/20240.202.48.1 to 240.202.63.254240.202.63.2554,094
165240.202.64.0/20240.202.64.1 to 240.202.79.254240.202.79.2554,094
166240.202.80.0/20240.202.80.1 to 240.202.95.254240.202.95.2554,094
167240.202.96.0/20240.202.96.1 to 240.202.111.254240.202.111.2554,094
168240.202.112.0/20240.202.112.1 to 240.202.127.254240.202.127.2554,094
169240.202.128.0/20240.202.128.1 to 240.202.143.254240.202.143.2554,094
170240.202.144.0/20240.202.144.1 to 240.202.159.254240.202.159.2554,094
171240.202.160.0/20240.202.160.1 to 240.202.175.254240.202.175.2554,094
172240.202.176.0/20240.202.176.1 to 240.202.191.254240.202.191.2554,094
173240.202.192.0/20240.202.192.1 to 240.202.207.254240.202.207.2554,094
174240.202.208.0/20240.202.208.1 to 240.202.223.254240.202.223.2554,094
175240.202.224.0/20240.202.224.1 to 240.202.239.254240.202.239.2554,094
176240.202.240.0/20240.202.240.1 to 240.202.255.254240.202.255.2554,094
177240.203.0.0/20240.203.0.1 to 240.203.15.254240.203.15.2554,094
178240.203.16.0/20240.203.16.1 to 240.203.31.254240.203.31.2554,094
179240.203.32.0/20240.203.32.1 to 240.203.47.254240.203.47.2554,094
180240.203.48.0/20240.203.48.1 to 240.203.63.254240.203.63.2554,094
181240.203.64.0/20240.203.64.1 to 240.203.79.254240.203.79.2554,094
182240.203.80.0/20240.203.80.1 to 240.203.95.254240.203.95.2554,094
183240.203.96.0/20240.203.96.1 to 240.203.111.254240.203.111.2554,094
184240.203.112.0/20240.203.112.1 to 240.203.127.254240.203.127.2554,094
185240.203.128.0/20240.203.128.1 to 240.203.143.254240.203.143.2554,094
186240.203.144.0/20240.203.144.1 to 240.203.159.254240.203.159.2554,094
187240.203.160.0/20240.203.160.1 to 240.203.175.254240.203.175.2554,094
188240.203.176.0/20240.203.176.1 to 240.203.191.254240.203.191.2554,094
189240.203.192.0/20240.203.192.1 to 240.203.207.254240.203.207.2554,094
190240.203.208.0/20240.203.208.1 to 240.203.223.254240.203.223.2554,094
191240.203.224.0/20240.203.224.1 to 240.203.239.254240.203.239.2554,094
192240.203.240.0/20240.203.240.1 to 240.203.255.254240.203.255.2554,094
193240.204.0.0/20240.204.0.1 to 240.204.15.254240.204.15.2554,094
194240.204.16.0/20240.204.16.1 to 240.204.31.254240.204.31.2554,094
195240.204.32.0/20240.204.32.1 to 240.204.47.254240.204.47.2554,094
196240.204.48.0/20240.204.48.1 to 240.204.63.254240.204.63.2554,094
197240.204.64.0/20240.204.64.1 to 240.204.79.254240.204.79.2554,094
198240.204.80.0/20240.204.80.1 to 240.204.95.254240.204.95.2554,094
199240.204.96.0/20240.204.96.1 to 240.204.111.254240.204.111.2554,094
200240.204.112.0/20240.204.112.1 to 240.204.127.254240.204.127.2554,094
201240.204.128.0/20240.204.128.1 to 240.204.143.254240.204.143.2554,094
202240.204.144.0/20240.204.144.1 to 240.204.159.254240.204.159.2554,094
203240.204.160.0/20240.204.160.1 to 240.204.175.254240.204.175.2554,094
204240.204.176.0/20240.204.176.1 to 240.204.191.254240.204.191.2554,094
205240.204.192.0/20240.204.192.1 to 240.204.207.254240.204.207.2554,094
206240.204.208.0/20240.204.208.1 to 240.204.223.254240.204.223.2554,094
207240.204.224.0/20240.204.224.1 to 240.204.239.254240.204.239.2554,094
208240.204.240.0/20240.204.240.1 to 240.204.255.254240.204.255.2554,094
209240.205.0.0/20240.205.0.1 to 240.205.15.254240.205.15.2554,094
210240.205.16.0/20240.205.16.1 to 240.205.31.254240.205.31.2554,094
211240.205.32.0/20240.205.32.1 to 240.205.47.254240.205.47.2554,094
212240.205.48.0/20240.205.48.1 to 240.205.63.254240.205.63.2554,094
213240.205.64.0/20240.205.64.1 to 240.205.79.254240.205.79.2554,094
214240.205.80.0/20240.205.80.1 to 240.205.95.254240.205.95.2554,094
215240.205.96.0/20240.205.96.1 to 240.205.111.254240.205.111.2554,094
216240.205.112.0/20240.205.112.1 to 240.205.127.254240.205.127.2554,094
217240.205.128.0/20240.205.128.1 to 240.205.143.254240.205.143.2554,094
218240.205.144.0/20240.205.144.1 to 240.205.159.254240.205.159.2554,094
219240.205.160.0/20240.205.160.1 to 240.205.175.254240.205.175.2554,094
220240.205.176.0/20240.205.176.1 to 240.205.191.254240.205.191.2554,094
221240.205.192.0/20240.205.192.1 to 240.205.207.254240.205.207.2554,094
222240.205.208.0/20240.205.208.1 to 240.205.223.254240.205.223.2554,094
223240.205.224.0/20240.205.224.1 to 240.205.239.254240.205.239.2554,094
224240.205.240.0/20240.205.240.1 to 240.205.255.254240.205.255.2554,094
225240.206.0.0/20240.206.0.1 to 240.206.15.254240.206.15.2554,094
226240.206.16.0/20240.206.16.1 to 240.206.31.254240.206.31.2554,094
227240.206.32.0/20240.206.32.1 to 240.206.47.254240.206.47.2554,094
228240.206.48.0/20240.206.48.1 to 240.206.63.254240.206.63.2554,094
229240.206.64.0/20240.206.64.1 to 240.206.79.254240.206.79.2554,094
230240.206.80.0/20240.206.80.1 to 240.206.95.254240.206.95.2554,094
231240.206.96.0/20240.206.96.1 to 240.206.111.254240.206.111.2554,094
232240.206.112.0/20240.206.112.1 to 240.206.127.254240.206.127.2554,094
233240.206.128.0/20240.206.128.1 to 240.206.143.254240.206.143.2554,094
234240.206.144.0/20240.206.144.1 to 240.206.159.254240.206.159.2554,094
235240.206.160.0/20240.206.160.1 to 240.206.175.254240.206.175.2554,094
236240.206.176.0/20240.206.176.1 to 240.206.191.254240.206.191.2554,094
237240.206.192.0/20240.206.192.1 to 240.206.207.254240.206.207.2554,094
238240.206.208.0/20240.206.208.1 to 240.206.223.254240.206.223.2554,094
239240.206.224.0/20240.206.224.1 to 240.206.239.254240.206.239.2554,094
240240.206.240.0/20240.206.240.1 to 240.206.255.254240.206.255.2554,094
241240.207.0.0/20240.207.0.1 to 240.207.15.254240.207.15.2554,094
242240.207.16.0/20240.207.16.1 to 240.207.31.254240.207.31.2554,094
243240.207.32.0/20240.207.32.1 to 240.207.47.254240.207.47.2554,094
244240.207.48.0/20240.207.48.1 to 240.207.63.254240.207.63.2554,094
245240.207.64.0/20240.207.64.1 to 240.207.79.254240.207.79.2554,094
246240.207.80.0/20240.207.80.1 to 240.207.95.254240.207.95.2554,094
247240.207.96.0/20240.207.96.1 to 240.207.111.254240.207.111.2554,094
248240.207.112.0/20240.207.112.1 to 240.207.127.254240.207.127.2554,094
249240.207.128.0/20240.207.128.1 to 240.207.143.254240.207.143.2554,094
250240.207.144.0/20240.207.144.1 to 240.207.159.254240.207.159.2554,094
251240.207.160.0/20240.207.160.1 to 240.207.175.254240.207.175.2554,094
252240.207.176.0/20240.207.176.1 to 240.207.191.254240.207.191.2554,094
253240.207.192.0/20240.207.192.1 to 240.207.207.254240.207.207.2554,094
254240.207.208.0/20240.207.208.1 to 240.207.223.254240.207.223.2554,094
255240.207.224.0/20240.207.224.1 to 240.207.239.254240.207.239.2554,094
256240.207.240.0/20240.207.240.1 to 240.207.255.254240.207.255.2554,094

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.