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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.

Network168.96.0.0/12
Usable hosts1,048,574
Subnet mask255.240.0.0
Addresses1,048,576
Network address
168.96.0.0
Broadcast address
168.111.255.255
First usable
168.96.0.1
Last usable
168.111.255.254
Usable hosts
1,048,574 (1,048,576 less the network and broadcast addresses)
Subnet mask
255.240.0.0
Wildcard mask
0.15.255.255 (Cisco ACLs, OSPF)
Prefix length
/12
Type
Public public
Old class
B (default /16)
As numbers
Hex A8600000 · Integer 2824863744 to 2825912319
Reverse DNS zones
96.168.in-addr.arpa
97.168.in-addr.arpa
98.168.in-addr.arpa
99.168.in-addr.arpa
100.168.in-addr.arpa
101.168.in-addr.arpa
102.168.in-addr.arpa
103.168.in-addr.arpa
104.168.in-addr.arpa
105.168.in-addr.arpa
106.168.in-addr.arpa
107.168.in-addr.arpa
108.168.in-addr.arpa
109.168.in-addr.arpa
110.168.in-addr.arpa
111.168.in-addr.arpa
/12 is not on a 8-bit boundary, so it takes 16 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10101000.01100000.00000000.00000000168.96.0.0
Subnet mask11111111.11110000.00000000.00000000255.240.0.0
Network10101000.01100000.00000000.00000000168.96.0.0
Broadcast10101000.01101111.11111111.11111111168.111.255.255
Split into smaller subnets/21
/13 (2)/14 (4)/15 (8)/16 (16)/17 (32)/18 (64)/19 (128)/20 (256)/21 (512)/22 (1,024)/23 (2,048)/24 (4,096)

168.96.0.0/12 makes 512 subnets of /21; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1168.96.0.0/21168.96.0.1 to 168.96.7.254168.96.7.2552,046
2168.96.8.0/21168.96.8.1 to 168.96.15.254168.96.15.2552,046
3168.96.16.0/21168.96.16.1 to 168.96.23.254168.96.23.2552,046
4168.96.24.0/21168.96.24.1 to 168.96.31.254168.96.31.2552,046
5168.96.32.0/21168.96.32.1 to 168.96.39.254168.96.39.2552,046
6168.96.40.0/21168.96.40.1 to 168.96.47.254168.96.47.2552,046
7168.96.48.0/21168.96.48.1 to 168.96.55.254168.96.55.2552,046
8168.96.56.0/21168.96.56.1 to 168.96.63.254168.96.63.2552,046
9168.96.64.0/21168.96.64.1 to 168.96.71.254168.96.71.2552,046
10168.96.72.0/21168.96.72.1 to 168.96.79.254168.96.79.2552,046
11168.96.80.0/21168.96.80.1 to 168.96.87.254168.96.87.2552,046
12168.96.88.0/21168.96.88.1 to 168.96.95.254168.96.95.2552,046
13168.96.96.0/21168.96.96.1 to 168.96.103.254168.96.103.2552,046
14168.96.104.0/21168.96.104.1 to 168.96.111.254168.96.111.2552,046
15168.96.112.0/21168.96.112.1 to 168.96.119.254168.96.119.2552,046
16168.96.120.0/21168.96.120.1 to 168.96.127.254168.96.127.2552,046
17168.96.128.0/21168.96.128.1 to 168.96.135.254168.96.135.2552,046
18168.96.136.0/21168.96.136.1 to 168.96.143.254168.96.143.2552,046
19168.96.144.0/21168.96.144.1 to 168.96.151.254168.96.151.2552,046
20168.96.152.0/21168.96.152.1 to 168.96.159.254168.96.159.2552,046
21168.96.160.0/21168.96.160.1 to 168.96.167.254168.96.167.2552,046
22168.96.168.0/21168.96.168.1 to 168.96.175.254168.96.175.2552,046
23168.96.176.0/21168.96.176.1 to 168.96.183.254168.96.183.2552,046
24168.96.184.0/21168.96.184.1 to 168.96.191.254168.96.191.2552,046
25168.96.192.0/21168.96.192.1 to 168.96.199.254168.96.199.2552,046
26168.96.200.0/21168.96.200.1 to 168.96.207.254168.96.207.2552,046
27168.96.208.0/21168.96.208.1 to 168.96.215.254168.96.215.2552,046
28168.96.216.0/21168.96.216.1 to 168.96.223.254168.96.223.2552,046
29168.96.224.0/21168.96.224.1 to 168.96.231.254168.96.231.2552,046
30168.96.232.0/21168.96.232.1 to 168.96.239.254168.96.239.2552,046
31168.96.240.0/21168.96.240.1 to 168.96.247.254168.96.247.2552,046
32168.96.248.0/21168.96.248.1 to 168.96.255.254168.96.255.2552,046
33168.97.0.0/21168.97.0.1 to 168.97.7.254168.97.7.2552,046
34168.97.8.0/21168.97.8.1 to 168.97.15.254168.97.15.2552,046
35168.97.16.0/21168.97.16.1 to 168.97.23.254168.97.23.2552,046
36168.97.24.0/21168.97.24.1 to 168.97.31.254168.97.31.2552,046
37168.97.32.0/21168.97.32.1 to 168.97.39.254168.97.39.2552,046
38168.97.40.0/21168.97.40.1 to 168.97.47.254168.97.47.2552,046
39168.97.48.0/21168.97.48.1 to 168.97.55.254168.97.55.2552,046
40168.97.56.0/21168.97.56.1 to 168.97.63.254168.97.63.2552,046
41168.97.64.0/21168.97.64.1 to 168.97.71.254168.97.71.2552,046
42168.97.72.0/21168.97.72.1 to 168.97.79.254168.97.79.2552,046
43168.97.80.0/21168.97.80.1 to 168.97.87.254168.97.87.2552,046
44168.97.88.0/21168.97.88.1 to 168.97.95.254168.97.95.2552,046
45168.97.96.0/21168.97.96.1 to 168.97.103.254168.97.103.2552,046
46168.97.104.0/21168.97.104.1 to 168.97.111.254168.97.111.2552,046
47168.97.112.0/21168.97.112.1 to 168.97.119.254168.97.119.2552,046
48168.97.120.0/21168.97.120.1 to 168.97.127.254168.97.127.2552,046
49168.97.128.0/21168.97.128.1 to 168.97.135.254168.97.135.2552,046
50168.97.136.0/21168.97.136.1 to 168.97.143.254168.97.143.2552,046
51168.97.144.0/21168.97.144.1 to 168.97.151.254168.97.151.2552,046
52168.97.152.0/21168.97.152.1 to 168.97.159.254168.97.159.2552,046
53168.97.160.0/21168.97.160.1 to 168.97.167.254168.97.167.2552,046
54168.97.168.0/21168.97.168.1 to 168.97.175.254168.97.175.2552,046
55168.97.176.0/21168.97.176.1 to 168.97.183.254168.97.183.2552,046
56168.97.184.0/21168.97.184.1 to 168.97.191.254168.97.191.2552,046
57168.97.192.0/21168.97.192.1 to 168.97.199.254168.97.199.2552,046
58168.97.200.0/21168.97.200.1 to 168.97.207.254168.97.207.2552,046
59168.97.208.0/21168.97.208.1 to 168.97.215.254168.97.215.2552,046
60168.97.216.0/21168.97.216.1 to 168.97.223.254168.97.223.2552,046
61168.97.224.0/21168.97.224.1 to 168.97.231.254168.97.231.2552,046
62168.97.232.0/21168.97.232.1 to 168.97.239.254168.97.239.2552,046
63168.97.240.0/21168.97.240.1 to 168.97.247.254168.97.247.2552,046
64168.97.248.0/21168.97.248.1 to 168.97.255.254168.97.255.2552,046
65168.98.0.0/21168.98.0.1 to 168.98.7.254168.98.7.2552,046
66168.98.8.0/21168.98.8.1 to 168.98.15.254168.98.15.2552,046
67168.98.16.0/21168.98.16.1 to 168.98.23.254168.98.23.2552,046
68168.98.24.0/21168.98.24.1 to 168.98.31.254168.98.31.2552,046
69168.98.32.0/21168.98.32.1 to 168.98.39.254168.98.39.2552,046
70168.98.40.0/21168.98.40.1 to 168.98.47.254168.98.47.2552,046
71168.98.48.0/21168.98.48.1 to 168.98.55.254168.98.55.2552,046
72168.98.56.0/21168.98.56.1 to 168.98.63.254168.98.63.2552,046
73168.98.64.0/21168.98.64.1 to 168.98.71.254168.98.71.2552,046
74168.98.72.0/21168.98.72.1 to 168.98.79.254168.98.79.2552,046
75168.98.80.0/21168.98.80.1 to 168.98.87.254168.98.87.2552,046
76168.98.88.0/21168.98.88.1 to 168.98.95.254168.98.95.2552,046
77168.98.96.0/21168.98.96.1 to 168.98.103.254168.98.103.2552,046
78168.98.104.0/21168.98.104.1 to 168.98.111.254168.98.111.2552,046
79168.98.112.0/21168.98.112.1 to 168.98.119.254168.98.119.2552,046
80168.98.120.0/21168.98.120.1 to 168.98.127.254168.98.127.2552,046
81168.98.128.0/21168.98.128.1 to 168.98.135.254168.98.135.2552,046
82168.98.136.0/21168.98.136.1 to 168.98.143.254168.98.143.2552,046
83168.98.144.0/21168.98.144.1 to 168.98.151.254168.98.151.2552,046
84168.98.152.0/21168.98.152.1 to 168.98.159.254168.98.159.2552,046
85168.98.160.0/21168.98.160.1 to 168.98.167.254168.98.167.2552,046
86168.98.168.0/21168.98.168.1 to 168.98.175.254168.98.175.2552,046
87168.98.176.0/21168.98.176.1 to 168.98.183.254168.98.183.2552,046
88168.98.184.0/21168.98.184.1 to 168.98.191.254168.98.191.2552,046
89168.98.192.0/21168.98.192.1 to 168.98.199.254168.98.199.2552,046
90168.98.200.0/21168.98.200.1 to 168.98.207.254168.98.207.2552,046
91168.98.208.0/21168.98.208.1 to 168.98.215.254168.98.215.2552,046
92168.98.216.0/21168.98.216.1 to 168.98.223.254168.98.223.2552,046
93168.98.224.0/21168.98.224.1 to 168.98.231.254168.98.231.2552,046
94168.98.232.0/21168.98.232.1 to 168.98.239.254168.98.239.2552,046
95168.98.240.0/21168.98.240.1 to 168.98.247.254168.98.247.2552,046
96168.98.248.0/21168.98.248.1 to 168.98.255.254168.98.255.2552,046
97168.99.0.0/21168.99.0.1 to 168.99.7.254168.99.7.2552,046
98168.99.8.0/21168.99.8.1 to 168.99.15.254168.99.15.2552,046
99168.99.16.0/21168.99.16.1 to 168.99.23.254168.99.23.2552,046
100168.99.24.0/21168.99.24.1 to 168.99.31.254168.99.31.2552,046
101168.99.32.0/21168.99.32.1 to 168.99.39.254168.99.39.2552,046
102168.99.40.0/21168.99.40.1 to 168.99.47.254168.99.47.2552,046
103168.99.48.0/21168.99.48.1 to 168.99.55.254168.99.55.2552,046
104168.99.56.0/21168.99.56.1 to 168.99.63.254168.99.63.2552,046
105168.99.64.0/21168.99.64.1 to 168.99.71.254168.99.71.2552,046
106168.99.72.0/21168.99.72.1 to 168.99.79.254168.99.79.2552,046
107168.99.80.0/21168.99.80.1 to 168.99.87.254168.99.87.2552,046
108168.99.88.0/21168.99.88.1 to 168.99.95.254168.99.95.2552,046
109168.99.96.0/21168.99.96.1 to 168.99.103.254168.99.103.2552,046
110168.99.104.0/21168.99.104.1 to 168.99.111.254168.99.111.2552,046
111168.99.112.0/21168.99.112.1 to 168.99.119.254168.99.119.2552,046
112168.99.120.0/21168.99.120.1 to 168.99.127.254168.99.127.2552,046
113168.99.128.0/21168.99.128.1 to 168.99.135.254168.99.135.2552,046
114168.99.136.0/21168.99.136.1 to 168.99.143.254168.99.143.2552,046
115168.99.144.0/21168.99.144.1 to 168.99.151.254168.99.151.2552,046
116168.99.152.0/21168.99.152.1 to 168.99.159.254168.99.159.2552,046
117168.99.160.0/21168.99.160.1 to 168.99.167.254168.99.167.2552,046
118168.99.168.0/21168.99.168.1 to 168.99.175.254168.99.175.2552,046
119168.99.176.0/21168.99.176.1 to 168.99.183.254168.99.183.2552,046
120168.99.184.0/21168.99.184.1 to 168.99.191.254168.99.191.2552,046
121168.99.192.0/21168.99.192.1 to 168.99.199.254168.99.199.2552,046
122168.99.200.0/21168.99.200.1 to 168.99.207.254168.99.207.2552,046
123168.99.208.0/21168.99.208.1 to 168.99.215.254168.99.215.2552,046
124168.99.216.0/21168.99.216.1 to 168.99.223.254168.99.223.2552,046
125168.99.224.0/21168.99.224.1 to 168.99.231.254168.99.231.2552,046
126168.99.232.0/21168.99.232.1 to 168.99.239.254168.99.239.2552,046
127168.99.240.0/21168.99.240.1 to 168.99.247.254168.99.247.2552,046
128168.99.248.0/21168.99.248.1 to 168.99.255.254168.99.255.2552,046
129168.100.0.0/21168.100.0.1 to 168.100.7.254168.100.7.2552,046
130168.100.8.0/21168.100.8.1 to 168.100.15.254168.100.15.2552,046
131168.100.16.0/21168.100.16.1 to 168.100.23.254168.100.23.2552,046
132168.100.24.0/21168.100.24.1 to 168.100.31.254168.100.31.2552,046
133168.100.32.0/21168.100.32.1 to 168.100.39.254168.100.39.2552,046
134168.100.40.0/21168.100.40.1 to 168.100.47.254168.100.47.2552,046
135168.100.48.0/21168.100.48.1 to 168.100.55.254168.100.55.2552,046
136168.100.56.0/21168.100.56.1 to 168.100.63.254168.100.63.2552,046
137168.100.64.0/21168.100.64.1 to 168.100.71.254168.100.71.2552,046
138168.100.72.0/21168.100.72.1 to 168.100.79.254168.100.79.2552,046
139168.100.80.0/21168.100.80.1 to 168.100.87.254168.100.87.2552,046
140168.100.88.0/21168.100.88.1 to 168.100.95.254168.100.95.2552,046
141168.100.96.0/21168.100.96.1 to 168.100.103.254168.100.103.2552,046
142168.100.104.0/21168.100.104.1 to 168.100.111.254168.100.111.2552,046
143168.100.112.0/21168.100.112.1 to 168.100.119.254168.100.119.2552,046
144168.100.120.0/21168.100.120.1 to 168.100.127.254168.100.127.2552,046
145168.100.128.0/21168.100.128.1 to 168.100.135.254168.100.135.2552,046
146168.100.136.0/21168.100.136.1 to 168.100.143.254168.100.143.2552,046
147168.100.144.0/21168.100.144.1 to 168.100.151.254168.100.151.2552,046
148168.100.152.0/21168.100.152.1 to 168.100.159.254168.100.159.2552,046
149168.100.160.0/21168.100.160.1 to 168.100.167.254168.100.167.2552,046
150168.100.168.0/21168.100.168.1 to 168.100.175.254168.100.175.2552,046
151168.100.176.0/21168.100.176.1 to 168.100.183.254168.100.183.2552,046
152168.100.184.0/21168.100.184.1 to 168.100.191.254168.100.191.2552,046
153168.100.192.0/21168.100.192.1 to 168.100.199.254168.100.199.2552,046
154168.100.200.0/21168.100.200.1 to 168.100.207.254168.100.207.2552,046
155168.100.208.0/21168.100.208.1 to 168.100.215.254168.100.215.2552,046
156168.100.216.0/21168.100.216.1 to 168.100.223.254168.100.223.2552,046
157168.100.224.0/21168.100.224.1 to 168.100.231.254168.100.231.2552,046
158168.100.232.0/21168.100.232.1 to 168.100.239.254168.100.239.2552,046
159168.100.240.0/21168.100.240.1 to 168.100.247.254168.100.247.2552,046
160168.100.248.0/21168.100.248.1 to 168.100.255.254168.100.255.2552,046
161168.101.0.0/21168.101.0.1 to 168.101.7.254168.101.7.2552,046
162168.101.8.0/21168.101.8.1 to 168.101.15.254168.101.15.2552,046
163168.101.16.0/21168.101.16.1 to 168.101.23.254168.101.23.2552,046
164168.101.24.0/21168.101.24.1 to 168.101.31.254168.101.31.2552,046
165168.101.32.0/21168.101.32.1 to 168.101.39.254168.101.39.2552,046
166168.101.40.0/21168.101.40.1 to 168.101.47.254168.101.47.2552,046
167168.101.48.0/21168.101.48.1 to 168.101.55.254168.101.55.2552,046
168168.101.56.0/21168.101.56.1 to 168.101.63.254168.101.63.2552,046
169168.101.64.0/21168.101.64.1 to 168.101.71.254168.101.71.2552,046
170168.101.72.0/21168.101.72.1 to 168.101.79.254168.101.79.2552,046
171168.101.80.0/21168.101.80.1 to 168.101.87.254168.101.87.2552,046
172168.101.88.0/21168.101.88.1 to 168.101.95.254168.101.95.2552,046
173168.101.96.0/21168.101.96.1 to 168.101.103.254168.101.103.2552,046
174168.101.104.0/21168.101.104.1 to 168.101.111.254168.101.111.2552,046
175168.101.112.0/21168.101.112.1 to 168.101.119.254168.101.119.2552,046
176168.101.120.0/21168.101.120.1 to 168.101.127.254168.101.127.2552,046
177168.101.128.0/21168.101.128.1 to 168.101.135.254168.101.135.2552,046
178168.101.136.0/21168.101.136.1 to 168.101.143.254168.101.143.2552,046
179168.101.144.0/21168.101.144.1 to 168.101.151.254168.101.151.2552,046
180168.101.152.0/21168.101.152.1 to 168.101.159.254168.101.159.2552,046
181168.101.160.0/21168.101.160.1 to 168.101.167.254168.101.167.2552,046
182168.101.168.0/21168.101.168.1 to 168.101.175.254168.101.175.2552,046
183168.101.176.0/21168.101.176.1 to 168.101.183.254168.101.183.2552,046
184168.101.184.0/21168.101.184.1 to 168.101.191.254168.101.191.2552,046
185168.101.192.0/21168.101.192.1 to 168.101.199.254168.101.199.2552,046
186168.101.200.0/21168.101.200.1 to 168.101.207.254168.101.207.2552,046
187168.101.208.0/21168.101.208.1 to 168.101.215.254168.101.215.2552,046
188168.101.216.0/21168.101.216.1 to 168.101.223.254168.101.223.2552,046
189168.101.224.0/21168.101.224.1 to 168.101.231.254168.101.231.2552,046
190168.101.232.0/21168.101.232.1 to 168.101.239.254168.101.239.2552,046
191168.101.240.0/21168.101.240.1 to 168.101.247.254168.101.247.2552,046
192168.101.248.0/21168.101.248.1 to 168.101.255.254168.101.255.2552,046
193168.102.0.0/21168.102.0.1 to 168.102.7.254168.102.7.2552,046
194168.102.8.0/21168.102.8.1 to 168.102.15.254168.102.15.2552,046
195168.102.16.0/21168.102.16.1 to 168.102.23.254168.102.23.2552,046
196168.102.24.0/21168.102.24.1 to 168.102.31.254168.102.31.2552,046
197168.102.32.0/21168.102.32.1 to 168.102.39.254168.102.39.2552,046
198168.102.40.0/21168.102.40.1 to 168.102.47.254168.102.47.2552,046
199168.102.48.0/21168.102.48.1 to 168.102.55.254168.102.55.2552,046
200168.102.56.0/21168.102.56.1 to 168.102.63.254168.102.63.2552,046
201168.102.64.0/21168.102.64.1 to 168.102.71.254168.102.71.2552,046
202168.102.72.0/21168.102.72.1 to 168.102.79.254168.102.79.2552,046
203168.102.80.0/21168.102.80.1 to 168.102.87.254168.102.87.2552,046
204168.102.88.0/21168.102.88.1 to 168.102.95.254168.102.95.2552,046
205168.102.96.0/21168.102.96.1 to 168.102.103.254168.102.103.2552,046
206168.102.104.0/21168.102.104.1 to 168.102.111.254168.102.111.2552,046
207168.102.112.0/21168.102.112.1 to 168.102.119.254168.102.119.2552,046
208168.102.120.0/21168.102.120.1 to 168.102.127.254168.102.127.2552,046
209168.102.128.0/21168.102.128.1 to 168.102.135.254168.102.135.2552,046
210168.102.136.0/21168.102.136.1 to 168.102.143.254168.102.143.2552,046
211168.102.144.0/21168.102.144.1 to 168.102.151.254168.102.151.2552,046
212168.102.152.0/21168.102.152.1 to 168.102.159.254168.102.159.2552,046
213168.102.160.0/21168.102.160.1 to 168.102.167.254168.102.167.2552,046
214168.102.168.0/21168.102.168.1 to 168.102.175.254168.102.175.2552,046
215168.102.176.0/21168.102.176.1 to 168.102.183.254168.102.183.2552,046
216168.102.184.0/21168.102.184.1 to 168.102.191.254168.102.191.2552,046
217168.102.192.0/21168.102.192.1 to 168.102.199.254168.102.199.2552,046
218168.102.200.0/21168.102.200.1 to 168.102.207.254168.102.207.2552,046
219168.102.208.0/21168.102.208.1 to 168.102.215.254168.102.215.2552,046
220168.102.216.0/21168.102.216.1 to 168.102.223.254168.102.223.2552,046
221168.102.224.0/21168.102.224.1 to 168.102.231.254168.102.231.2552,046
222168.102.232.0/21168.102.232.1 to 168.102.239.254168.102.239.2552,046
223168.102.240.0/21168.102.240.1 to 168.102.247.254168.102.247.2552,046
224168.102.248.0/21168.102.248.1 to 168.102.255.254168.102.255.2552,046
225168.103.0.0/21168.103.0.1 to 168.103.7.254168.103.7.2552,046
226168.103.8.0/21168.103.8.1 to 168.103.15.254168.103.15.2552,046
227168.103.16.0/21168.103.16.1 to 168.103.23.254168.103.23.2552,046
228168.103.24.0/21168.103.24.1 to 168.103.31.254168.103.31.2552,046
229168.103.32.0/21168.103.32.1 to 168.103.39.254168.103.39.2552,046
230168.103.40.0/21168.103.40.1 to 168.103.47.254168.103.47.2552,046
231168.103.48.0/21168.103.48.1 to 168.103.55.254168.103.55.2552,046
232168.103.56.0/21168.103.56.1 to 168.103.63.254168.103.63.2552,046
233168.103.64.0/21168.103.64.1 to 168.103.71.254168.103.71.2552,046
234168.103.72.0/21168.103.72.1 to 168.103.79.254168.103.79.2552,046
235168.103.80.0/21168.103.80.1 to 168.103.87.254168.103.87.2552,046
236168.103.88.0/21168.103.88.1 to 168.103.95.254168.103.95.2552,046
237168.103.96.0/21168.103.96.1 to 168.103.103.254168.103.103.2552,046
238168.103.104.0/21168.103.104.1 to 168.103.111.254168.103.111.2552,046
239168.103.112.0/21168.103.112.1 to 168.103.119.254168.103.119.2552,046
240168.103.120.0/21168.103.120.1 to 168.103.127.254168.103.127.2552,046
241168.103.128.0/21168.103.128.1 to 168.103.135.254168.103.135.2552,046
242168.103.136.0/21168.103.136.1 to 168.103.143.254168.103.143.2552,046
243168.103.144.0/21168.103.144.1 to 168.103.151.254168.103.151.2552,046
244168.103.152.0/21168.103.152.1 to 168.103.159.254168.103.159.2552,046
245168.103.160.0/21168.103.160.1 to 168.103.167.254168.103.167.2552,046
246168.103.168.0/21168.103.168.1 to 168.103.175.254168.103.175.2552,046
247168.103.176.0/21168.103.176.1 to 168.103.183.254168.103.183.2552,046
248168.103.184.0/21168.103.184.1 to 168.103.191.254168.103.191.2552,046
249168.103.192.0/21168.103.192.1 to 168.103.199.254168.103.199.2552,046
250168.103.200.0/21168.103.200.1 to 168.103.207.254168.103.207.2552,046
251168.103.208.0/21168.103.208.1 to 168.103.215.254168.103.215.2552,046
252168.103.216.0/21168.103.216.1 to 168.103.223.254168.103.223.2552,046
253168.103.224.0/21168.103.224.1 to 168.103.231.254168.103.231.2552,046
254168.103.232.0/21168.103.232.1 to 168.103.239.254168.103.239.2552,046
255168.103.240.0/21168.103.240.1 to 168.103.247.254168.103.247.2552,046
256168.103.248.0/21168.103.248.1 to 168.103.255.254168.103.255.2552,046

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.