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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.

Network217.2.192.0/18
Usable hosts16,382
Subnet mask255.255.192.0
Addresses16,384
Network address
217.2.192.0
Broadcast address
217.2.255.255
First usable
217.2.192.1
Last usable
217.2.255.254
Usable hosts
16,382 (16,384 less the network and broadcast addresses)
Subnet mask
255.255.192.0
Wildcard mask
0.0.63.255 (Cisco ACLs, OSPF)
Prefix length
/18
Type
Public public
Old class
C (default /24)
As numbers
Hex D902C000 · Integer 3640836096 to 3640852479
Reverse DNS zones
192.2.217.in-addr.arpa
193.2.217.in-addr.arpa
194.2.217.in-addr.arpa
195.2.217.in-addr.arpa
196.2.217.in-addr.arpa
197.2.217.in-addr.arpa
198.2.217.in-addr.arpa
199.2.217.in-addr.arpa
200.2.217.in-addr.arpa
201.2.217.in-addr.arpa
202.2.217.in-addr.arpa
203.2.217.in-addr.arpa
204.2.217.in-addr.arpa
205.2.217.in-addr.arpa
206.2.217.in-addr.arpa
207.2.217.in-addr.arpa
and 48 more
/18 is not on a 8-bit boundary, so it takes 64 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11011001.00000010.11000000.00000000217.2.192.0
Subnet mask11111111.11111111.11000000.00000000255.255.192.0
Network11011001.00000010.11000000.00000000217.2.192.0
Broadcast11011001.00000010.11111111.11111111217.2.255.255
Split into smaller subnets/27
/19 (2)/20 (4)/21 (8)/22 (16)/23 (32)/24 (64)/25 (128)/26 (256)/27 (512)/28 (1,024)/29 (2,048)/30 (4,096)

217.2.192.0/18 makes 512 subnets of /27; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1217.2.192.0/27217.2.192.1 to 217.2.192.30217.2.192.3130
2217.2.192.32/27217.2.192.33 to 217.2.192.62217.2.192.6330
3217.2.192.64/27217.2.192.65 to 217.2.192.94217.2.192.9530
4217.2.192.96/27217.2.192.97 to 217.2.192.126217.2.192.12730
5217.2.192.128/27217.2.192.129 to 217.2.192.158217.2.192.15930
6217.2.192.160/27217.2.192.161 to 217.2.192.190217.2.192.19130
7217.2.192.192/27217.2.192.193 to 217.2.192.222217.2.192.22330
8217.2.192.224/27217.2.192.225 to 217.2.192.254217.2.192.25530
9217.2.193.0/27217.2.193.1 to 217.2.193.30217.2.193.3130
10217.2.193.32/27217.2.193.33 to 217.2.193.62217.2.193.6330
11217.2.193.64/27217.2.193.65 to 217.2.193.94217.2.193.9530
12217.2.193.96/27217.2.193.97 to 217.2.193.126217.2.193.12730
13217.2.193.128/27217.2.193.129 to 217.2.193.158217.2.193.15930
14217.2.193.160/27217.2.193.161 to 217.2.193.190217.2.193.19130
15217.2.193.192/27217.2.193.193 to 217.2.193.222217.2.193.22330
16217.2.193.224/27217.2.193.225 to 217.2.193.254217.2.193.25530
17217.2.194.0/27217.2.194.1 to 217.2.194.30217.2.194.3130
18217.2.194.32/27217.2.194.33 to 217.2.194.62217.2.194.6330
19217.2.194.64/27217.2.194.65 to 217.2.194.94217.2.194.9530
20217.2.194.96/27217.2.194.97 to 217.2.194.126217.2.194.12730
21217.2.194.128/27217.2.194.129 to 217.2.194.158217.2.194.15930
22217.2.194.160/27217.2.194.161 to 217.2.194.190217.2.194.19130
23217.2.194.192/27217.2.194.193 to 217.2.194.222217.2.194.22330
24217.2.194.224/27217.2.194.225 to 217.2.194.254217.2.194.25530
25217.2.195.0/27217.2.195.1 to 217.2.195.30217.2.195.3130
26217.2.195.32/27217.2.195.33 to 217.2.195.62217.2.195.6330
27217.2.195.64/27217.2.195.65 to 217.2.195.94217.2.195.9530
28217.2.195.96/27217.2.195.97 to 217.2.195.126217.2.195.12730
29217.2.195.128/27217.2.195.129 to 217.2.195.158217.2.195.15930
30217.2.195.160/27217.2.195.161 to 217.2.195.190217.2.195.19130
31217.2.195.192/27217.2.195.193 to 217.2.195.222217.2.195.22330
32217.2.195.224/27217.2.195.225 to 217.2.195.254217.2.195.25530
33217.2.196.0/27217.2.196.1 to 217.2.196.30217.2.196.3130
34217.2.196.32/27217.2.196.33 to 217.2.196.62217.2.196.6330
35217.2.196.64/27217.2.196.65 to 217.2.196.94217.2.196.9530
36217.2.196.96/27217.2.196.97 to 217.2.196.126217.2.196.12730
37217.2.196.128/27217.2.196.129 to 217.2.196.158217.2.196.15930
38217.2.196.160/27217.2.196.161 to 217.2.196.190217.2.196.19130
39217.2.196.192/27217.2.196.193 to 217.2.196.222217.2.196.22330
40217.2.196.224/27217.2.196.225 to 217.2.196.254217.2.196.25530
41217.2.197.0/27217.2.197.1 to 217.2.197.30217.2.197.3130
42217.2.197.32/27217.2.197.33 to 217.2.197.62217.2.197.6330
43217.2.197.64/27217.2.197.65 to 217.2.197.94217.2.197.9530
44217.2.197.96/27217.2.197.97 to 217.2.197.126217.2.197.12730
45217.2.197.128/27217.2.197.129 to 217.2.197.158217.2.197.15930
46217.2.197.160/27217.2.197.161 to 217.2.197.190217.2.197.19130
47217.2.197.192/27217.2.197.193 to 217.2.197.222217.2.197.22330
48217.2.197.224/27217.2.197.225 to 217.2.197.254217.2.197.25530
49217.2.198.0/27217.2.198.1 to 217.2.198.30217.2.198.3130
50217.2.198.32/27217.2.198.33 to 217.2.198.62217.2.198.6330
51217.2.198.64/27217.2.198.65 to 217.2.198.94217.2.198.9530
52217.2.198.96/27217.2.198.97 to 217.2.198.126217.2.198.12730
53217.2.198.128/27217.2.198.129 to 217.2.198.158217.2.198.15930
54217.2.198.160/27217.2.198.161 to 217.2.198.190217.2.198.19130
55217.2.198.192/27217.2.198.193 to 217.2.198.222217.2.198.22330
56217.2.198.224/27217.2.198.225 to 217.2.198.254217.2.198.25530
57217.2.199.0/27217.2.199.1 to 217.2.199.30217.2.199.3130
58217.2.199.32/27217.2.199.33 to 217.2.199.62217.2.199.6330
59217.2.199.64/27217.2.199.65 to 217.2.199.94217.2.199.9530
60217.2.199.96/27217.2.199.97 to 217.2.199.126217.2.199.12730
61217.2.199.128/27217.2.199.129 to 217.2.199.158217.2.199.15930
62217.2.199.160/27217.2.199.161 to 217.2.199.190217.2.199.19130
63217.2.199.192/27217.2.199.193 to 217.2.199.222217.2.199.22330
64217.2.199.224/27217.2.199.225 to 217.2.199.254217.2.199.25530
65217.2.200.0/27217.2.200.1 to 217.2.200.30217.2.200.3130
66217.2.200.32/27217.2.200.33 to 217.2.200.62217.2.200.6330
67217.2.200.64/27217.2.200.65 to 217.2.200.94217.2.200.9530
68217.2.200.96/27217.2.200.97 to 217.2.200.126217.2.200.12730
69217.2.200.128/27217.2.200.129 to 217.2.200.158217.2.200.15930
70217.2.200.160/27217.2.200.161 to 217.2.200.190217.2.200.19130
71217.2.200.192/27217.2.200.193 to 217.2.200.222217.2.200.22330
72217.2.200.224/27217.2.200.225 to 217.2.200.254217.2.200.25530
73217.2.201.0/27217.2.201.1 to 217.2.201.30217.2.201.3130
74217.2.201.32/27217.2.201.33 to 217.2.201.62217.2.201.6330
75217.2.201.64/27217.2.201.65 to 217.2.201.94217.2.201.9530
76217.2.201.96/27217.2.201.97 to 217.2.201.126217.2.201.12730
77217.2.201.128/27217.2.201.129 to 217.2.201.158217.2.201.15930
78217.2.201.160/27217.2.201.161 to 217.2.201.190217.2.201.19130
79217.2.201.192/27217.2.201.193 to 217.2.201.222217.2.201.22330
80217.2.201.224/27217.2.201.225 to 217.2.201.254217.2.201.25530
81217.2.202.0/27217.2.202.1 to 217.2.202.30217.2.202.3130
82217.2.202.32/27217.2.202.33 to 217.2.202.62217.2.202.6330
83217.2.202.64/27217.2.202.65 to 217.2.202.94217.2.202.9530
84217.2.202.96/27217.2.202.97 to 217.2.202.126217.2.202.12730
85217.2.202.128/27217.2.202.129 to 217.2.202.158217.2.202.15930
86217.2.202.160/27217.2.202.161 to 217.2.202.190217.2.202.19130
87217.2.202.192/27217.2.202.193 to 217.2.202.222217.2.202.22330
88217.2.202.224/27217.2.202.225 to 217.2.202.254217.2.202.25530
89217.2.203.0/27217.2.203.1 to 217.2.203.30217.2.203.3130
90217.2.203.32/27217.2.203.33 to 217.2.203.62217.2.203.6330
91217.2.203.64/27217.2.203.65 to 217.2.203.94217.2.203.9530
92217.2.203.96/27217.2.203.97 to 217.2.203.126217.2.203.12730
93217.2.203.128/27217.2.203.129 to 217.2.203.158217.2.203.15930
94217.2.203.160/27217.2.203.161 to 217.2.203.190217.2.203.19130
95217.2.203.192/27217.2.203.193 to 217.2.203.222217.2.203.22330
96217.2.203.224/27217.2.203.225 to 217.2.203.254217.2.203.25530
97217.2.204.0/27217.2.204.1 to 217.2.204.30217.2.204.3130
98217.2.204.32/27217.2.204.33 to 217.2.204.62217.2.204.6330
99217.2.204.64/27217.2.204.65 to 217.2.204.94217.2.204.9530
100217.2.204.96/27217.2.204.97 to 217.2.204.126217.2.204.12730
101217.2.204.128/27217.2.204.129 to 217.2.204.158217.2.204.15930
102217.2.204.160/27217.2.204.161 to 217.2.204.190217.2.204.19130
103217.2.204.192/27217.2.204.193 to 217.2.204.222217.2.204.22330
104217.2.204.224/27217.2.204.225 to 217.2.204.254217.2.204.25530
105217.2.205.0/27217.2.205.1 to 217.2.205.30217.2.205.3130
106217.2.205.32/27217.2.205.33 to 217.2.205.62217.2.205.6330
107217.2.205.64/27217.2.205.65 to 217.2.205.94217.2.205.9530
108217.2.205.96/27217.2.205.97 to 217.2.205.126217.2.205.12730
109217.2.205.128/27217.2.205.129 to 217.2.205.158217.2.205.15930
110217.2.205.160/27217.2.205.161 to 217.2.205.190217.2.205.19130
111217.2.205.192/27217.2.205.193 to 217.2.205.222217.2.205.22330
112217.2.205.224/27217.2.205.225 to 217.2.205.254217.2.205.25530
113217.2.206.0/27217.2.206.1 to 217.2.206.30217.2.206.3130
114217.2.206.32/27217.2.206.33 to 217.2.206.62217.2.206.6330
115217.2.206.64/27217.2.206.65 to 217.2.206.94217.2.206.9530
116217.2.206.96/27217.2.206.97 to 217.2.206.126217.2.206.12730
117217.2.206.128/27217.2.206.129 to 217.2.206.158217.2.206.15930
118217.2.206.160/27217.2.206.161 to 217.2.206.190217.2.206.19130
119217.2.206.192/27217.2.206.193 to 217.2.206.222217.2.206.22330
120217.2.206.224/27217.2.206.225 to 217.2.206.254217.2.206.25530
121217.2.207.0/27217.2.207.1 to 217.2.207.30217.2.207.3130
122217.2.207.32/27217.2.207.33 to 217.2.207.62217.2.207.6330
123217.2.207.64/27217.2.207.65 to 217.2.207.94217.2.207.9530
124217.2.207.96/27217.2.207.97 to 217.2.207.126217.2.207.12730
125217.2.207.128/27217.2.207.129 to 217.2.207.158217.2.207.15930
126217.2.207.160/27217.2.207.161 to 217.2.207.190217.2.207.19130
127217.2.207.192/27217.2.207.193 to 217.2.207.222217.2.207.22330
128217.2.207.224/27217.2.207.225 to 217.2.207.254217.2.207.25530
129217.2.208.0/27217.2.208.1 to 217.2.208.30217.2.208.3130
130217.2.208.32/27217.2.208.33 to 217.2.208.62217.2.208.6330
131217.2.208.64/27217.2.208.65 to 217.2.208.94217.2.208.9530
132217.2.208.96/27217.2.208.97 to 217.2.208.126217.2.208.12730
133217.2.208.128/27217.2.208.129 to 217.2.208.158217.2.208.15930
134217.2.208.160/27217.2.208.161 to 217.2.208.190217.2.208.19130
135217.2.208.192/27217.2.208.193 to 217.2.208.222217.2.208.22330
136217.2.208.224/27217.2.208.225 to 217.2.208.254217.2.208.25530
137217.2.209.0/27217.2.209.1 to 217.2.209.30217.2.209.3130
138217.2.209.32/27217.2.209.33 to 217.2.209.62217.2.209.6330
139217.2.209.64/27217.2.209.65 to 217.2.209.94217.2.209.9530
140217.2.209.96/27217.2.209.97 to 217.2.209.126217.2.209.12730
141217.2.209.128/27217.2.209.129 to 217.2.209.158217.2.209.15930
142217.2.209.160/27217.2.209.161 to 217.2.209.190217.2.209.19130
143217.2.209.192/27217.2.209.193 to 217.2.209.222217.2.209.22330
144217.2.209.224/27217.2.209.225 to 217.2.209.254217.2.209.25530
145217.2.210.0/27217.2.210.1 to 217.2.210.30217.2.210.3130
146217.2.210.32/27217.2.210.33 to 217.2.210.62217.2.210.6330
147217.2.210.64/27217.2.210.65 to 217.2.210.94217.2.210.9530
148217.2.210.96/27217.2.210.97 to 217.2.210.126217.2.210.12730
149217.2.210.128/27217.2.210.129 to 217.2.210.158217.2.210.15930
150217.2.210.160/27217.2.210.161 to 217.2.210.190217.2.210.19130
151217.2.210.192/27217.2.210.193 to 217.2.210.222217.2.210.22330
152217.2.210.224/27217.2.210.225 to 217.2.210.254217.2.210.25530
153217.2.211.0/27217.2.211.1 to 217.2.211.30217.2.211.3130
154217.2.211.32/27217.2.211.33 to 217.2.211.62217.2.211.6330
155217.2.211.64/27217.2.211.65 to 217.2.211.94217.2.211.9530
156217.2.211.96/27217.2.211.97 to 217.2.211.126217.2.211.12730
157217.2.211.128/27217.2.211.129 to 217.2.211.158217.2.211.15930
158217.2.211.160/27217.2.211.161 to 217.2.211.190217.2.211.19130
159217.2.211.192/27217.2.211.193 to 217.2.211.222217.2.211.22330
160217.2.211.224/27217.2.211.225 to 217.2.211.254217.2.211.25530
161217.2.212.0/27217.2.212.1 to 217.2.212.30217.2.212.3130
162217.2.212.32/27217.2.212.33 to 217.2.212.62217.2.212.6330
163217.2.212.64/27217.2.212.65 to 217.2.212.94217.2.212.9530
164217.2.212.96/27217.2.212.97 to 217.2.212.126217.2.212.12730
165217.2.212.128/27217.2.212.129 to 217.2.212.158217.2.212.15930
166217.2.212.160/27217.2.212.161 to 217.2.212.190217.2.212.19130
167217.2.212.192/27217.2.212.193 to 217.2.212.222217.2.212.22330
168217.2.212.224/27217.2.212.225 to 217.2.212.254217.2.212.25530
169217.2.213.0/27217.2.213.1 to 217.2.213.30217.2.213.3130
170217.2.213.32/27217.2.213.33 to 217.2.213.62217.2.213.6330
171217.2.213.64/27217.2.213.65 to 217.2.213.94217.2.213.9530
172217.2.213.96/27217.2.213.97 to 217.2.213.126217.2.213.12730
173217.2.213.128/27217.2.213.129 to 217.2.213.158217.2.213.15930
174217.2.213.160/27217.2.213.161 to 217.2.213.190217.2.213.19130
175217.2.213.192/27217.2.213.193 to 217.2.213.222217.2.213.22330
176217.2.213.224/27217.2.213.225 to 217.2.213.254217.2.213.25530
177217.2.214.0/27217.2.214.1 to 217.2.214.30217.2.214.3130
178217.2.214.32/27217.2.214.33 to 217.2.214.62217.2.214.6330
179217.2.214.64/27217.2.214.65 to 217.2.214.94217.2.214.9530
180217.2.214.96/27217.2.214.97 to 217.2.214.126217.2.214.12730
181217.2.214.128/27217.2.214.129 to 217.2.214.158217.2.214.15930
182217.2.214.160/27217.2.214.161 to 217.2.214.190217.2.214.19130
183217.2.214.192/27217.2.214.193 to 217.2.214.222217.2.214.22330
184217.2.214.224/27217.2.214.225 to 217.2.214.254217.2.214.25530
185217.2.215.0/27217.2.215.1 to 217.2.215.30217.2.215.3130
186217.2.215.32/27217.2.215.33 to 217.2.215.62217.2.215.6330
187217.2.215.64/27217.2.215.65 to 217.2.215.94217.2.215.9530
188217.2.215.96/27217.2.215.97 to 217.2.215.126217.2.215.12730
189217.2.215.128/27217.2.215.129 to 217.2.215.158217.2.215.15930
190217.2.215.160/27217.2.215.161 to 217.2.215.190217.2.215.19130
191217.2.215.192/27217.2.215.193 to 217.2.215.222217.2.215.22330
192217.2.215.224/27217.2.215.225 to 217.2.215.254217.2.215.25530
193217.2.216.0/27217.2.216.1 to 217.2.216.30217.2.216.3130
194217.2.216.32/27217.2.216.33 to 217.2.216.62217.2.216.6330
195217.2.216.64/27217.2.216.65 to 217.2.216.94217.2.216.9530
196217.2.216.96/27217.2.216.97 to 217.2.216.126217.2.216.12730
197217.2.216.128/27217.2.216.129 to 217.2.216.158217.2.216.15930
198217.2.216.160/27217.2.216.161 to 217.2.216.190217.2.216.19130
199217.2.216.192/27217.2.216.193 to 217.2.216.222217.2.216.22330
200217.2.216.224/27217.2.216.225 to 217.2.216.254217.2.216.25530
201217.2.217.0/27217.2.217.1 to 217.2.217.30217.2.217.3130
202217.2.217.32/27217.2.217.33 to 217.2.217.62217.2.217.6330
203217.2.217.64/27217.2.217.65 to 217.2.217.94217.2.217.9530
204217.2.217.96/27217.2.217.97 to 217.2.217.126217.2.217.12730
205217.2.217.128/27217.2.217.129 to 217.2.217.158217.2.217.15930
206217.2.217.160/27217.2.217.161 to 217.2.217.190217.2.217.19130
207217.2.217.192/27217.2.217.193 to 217.2.217.222217.2.217.22330
208217.2.217.224/27217.2.217.225 to 217.2.217.254217.2.217.25530
209217.2.218.0/27217.2.218.1 to 217.2.218.30217.2.218.3130
210217.2.218.32/27217.2.218.33 to 217.2.218.62217.2.218.6330
211217.2.218.64/27217.2.218.65 to 217.2.218.94217.2.218.9530
212217.2.218.96/27217.2.218.97 to 217.2.218.126217.2.218.12730
213217.2.218.128/27217.2.218.129 to 217.2.218.158217.2.218.15930
214217.2.218.160/27217.2.218.161 to 217.2.218.190217.2.218.19130
215217.2.218.192/27217.2.218.193 to 217.2.218.222217.2.218.22330
216217.2.218.224/27217.2.218.225 to 217.2.218.254217.2.218.25530
217217.2.219.0/27217.2.219.1 to 217.2.219.30217.2.219.3130
218217.2.219.32/27217.2.219.33 to 217.2.219.62217.2.219.6330
219217.2.219.64/27217.2.219.65 to 217.2.219.94217.2.219.9530
220217.2.219.96/27217.2.219.97 to 217.2.219.126217.2.219.12730
221217.2.219.128/27217.2.219.129 to 217.2.219.158217.2.219.15930
222217.2.219.160/27217.2.219.161 to 217.2.219.190217.2.219.19130
223217.2.219.192/27217.2.219.193 to 217.2.219.222217.2.219.22330
224217.2.219.224/27217.2.219.225 to 217.2.219.254217.2.219.25530
225217.2.220.0/27217.2.220.1 to 217.2.220.30217.2.220.3130
226217.2.220.32/27217.2.220.33 to 217.2.220.62217.2.220.6330
227217.2.220.64/27217.2.220.65 to 217.2.220.94217.2.220.9530
228217.2.220.96/27217.2.220.97 to 217.2.220.126217.2.220.12730
229217.2.220.128/27217.2.220.129 to 217.2.220.158217.2.220.15930
230217.2.220.160/27217.2.220.161 to 217.2.220.190217.2.220.19130
231217.2.220.192/27217.2.220.193 to 217.2.220.222217.2.220.22330
232217.2.220.224/27217.2.220.225 to 217.2.220.254217.2.220.25530
233217.2.221.0/27217.2.221.1 to 217.2.221.30217.2.221.3130
234217.2.221.32/27217.2.221.33 to 217.2.221.62217.2.221.6330
235217.2.221.64/27217.2.221.65 to 217.2.221.94217.2.221.9530
236217.2.221.96/27217.2.221.97 to 217.2.221.126217.2.221.12730
237217.2.221.128/27217.2.221.129 to 217.2.221.158217.2.221.15930
238217.2.221.160/27217.2.221.161 to 217.2.221.190217.2.221.19130
239217.2.221.192/27217.2.221.193 to 217.2.221.222217.2.221.22330
240217.2.221.224/27217.2.221.225 to 217.2.221.254217.2.221.25530
241217.2.222.0/27217.2.222.1 to 217.2.222.30217.2.222.3130
242217.2.222.32/27217.2.222.33 to 217.2.222.62217.2.222.6330
243217.2.222.64/27217.2.222.65 to 217.2.222.94217.2.222.9530
244217.2.222.96/27217.2.222.97 to 217.2.222.126217.2.222.12730
245217.2.222.128/27217.2.222.129 to 217.2.222.158217.2.222.15930
246217.2.222.160/27217.2.222.161 to 217.2.222.190217.2.222.19130
247217.2.222.192/27217.2.222.193 to 217.2.222.222217.2.222.22330
248217.2.222.224/27217.2.222.225 to 217.2.222.254217.2.222.25530
249217.2.223.0/27217.2.223.1 to 217.2.223.30217.2.223.3130
250217.2.223.32/27217.2.223.33 to 217.2.223.62217.2.223.6330
251217.2.223.64/27217.2.223.65 to 217.2.223.94217.2.223.9530
252217.2.223.96/27217.2.223.97 to 217.2.223.126217.2.223.12730
253217.2.223.128/27217.2.223.129 to 217.2.223.158217.2.223.15930
254217.2.223.160/27217.2.223.161 to 217.2.223.190217.2.223.19130
255217.2.223.192/27217.2.223.193 to 217.2.223.222217.2.223.22330
256217.2.223.224/27217.2.223.225 to 217.2.223.254217.2.223.25530

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.