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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.

Network168.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
168.0.0.0
Broadcast address
168.255.255.255
First usable
168.0.0.1
Last usable
168.255.255.254
Usable hosts
16,777,214 (16,777,216 less the network and broadcast addresses)
Subnet mask
255.0.0.0
Wildcard mask
0.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/8
Type
Public public
Old class
B (default /16)
As numbers
Hex A8000000 · Integer 2818572288 to 2835349503
Reverse DNS zone
168.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10101000..00000000.00000000.00000000168.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network10101000..00000000.00000000.00000000168.0.0.0
Broadcast10101000..11111111.11111111.11111111168.255.255.255
Split into smaller subnets/19
/9 (2)/10 (4)/11 (8)/12 (16)/13 (32)/14 (64)/15 (128)/16 (256)/17 (512)/18 (1,024)/19 (2,048)/20 (4,096)

168.0.0.0/8 makes 2,048 subnets of /19; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1168.0.0.0/19168.0.0.1 to 168.0.31.254168.0.31.2558,190
2168.0.32.0/19168.0.32.1 to 168.0.63.254168.0.63.2558,190
3168.0.64.0/19168.0.64.1 to 168.0.95.254168.0.95.2558,190
4168.0.96.0/19168.0.96.1 to 168.0.127.254168.0.127.2558,190
5168.0.128.0/19168.0.128.1 to 168.0.159.254168.0.159.2558,190
6168.0.160.0/19168.0.160.1 to 168.0.191.254168.0.191.2558,190
7168.0.192.0/19168.0.192.1 to 168.0.223.254168.0.223.2558,190
8168.0.224.0/19168.0.224.1 to 168.0.255.254168.0.255.2558,190
9168.1.0.0/19168.1.0.1 to 168.1.31.254168.1.31.2558,190
10168.1.32.0/19168.1.32.1 to 168.1.63.254168.1.63.2558,190
11168.1.64.0/19168.1.64.1 to 168.1.95.254168.1.95.2558,190
12168.1.96.0/19168.1.96.1 to 168.1.127.254168.1.127.2558,190
13168.1.128.0/19168.1.128.1 to 168.1.159.254168.1.159.2558,190
14168.1.160.0/19168.1.160.1 to 168.1.191.254168.1.191.2558,190
15168.1.192.0/19168.1.192.1 to 168.1.223.254168.1.223.2558,190
16168.1.224.0/19168.1.224.1 to 168.1.255.254168.1.255.2558,190
17168.2.0.0/19168.2.0.1 to 168.2.31.254168.2.31.2558,190
18168.2.32.0/19168.2.32.1 to 168.2.63.254168.2.63.2558,190
19168.2.64.0/19168.2.64.1 to 168.2.95.254168.2.95.2558,190
20168.2.96.0/19168.2.96.1 to 168.2.127.254168.2.127.2558,190
21168.2.128.0/19168.2.128.1 to 168.2.159.254168.2.159.2558,190
22168.2.160.0/19168.2.160.1 to 168.2.191.254168.2.191.2558,190
23168.2.192.0/19168.2.192.1 to 168.2.223.254168.2.223.2558,190
24168.2.224.0/19168.2.224.1 to 168.2.255.254168.2.255.2558,190
25168.3.0.0/19168.3.0.1 to 168.3.31.254168.3.31.2558,190
26168.3.32.0/19168.3.32.1 to 168.3.63.254168.3.63.2558,190
27168.3.64.0/19168.3.64.1 to 168.3.95.254168.3.95.2558,190
28168.3.96.0/19168.3.96.1 to 168.3.127.254168.3.127.2558,190
29168.3.128.0/19168.3.128.1 to 168.3.159.254168.3.159.2558,190
30168.3.160.0/19168.3.160.1 to 168.3.191.254168.3.191.2558,190
31168.3.192.0/19168.3.192.1 to 168.3.223.254168.3.223.2558,190
32168.3.224.0/19168.3.224.1 to 168.3.255.254168.3.255.2558,190
33168.4.0.0/19168.4.0.1 to 168.4.31.254168.4.31.2558,190
34168.4.32.0/19168.4.32.1 to 168.4.63.254168.4.63.2558,190
35168.4.64.0/19168.4.64.1 to 168.4.95.254168.4.95.2558,190
36168.4.96.0/19168.4.96.1 to 168.4.127.254168.4.127.2558,190
37168.4.128.0/19168.4.128.1 to 168.4.159.254168.4.159.2558,190
38168.4.160.0/19168.4.160.1 to 168.4.191.254168.4.191.2558,190
39168.4.192.0/19168.4.192.1 to 168.4.223.254168.4.223.2558,190
40168.4.224.0/19168.4.224.1 to 168.4.255.254168.4.255.2558,190
41168.5.0.0/19168.5.0.1 to 168.5.31.254168.5.31.2558,190
42168.5.32.0/19168.5.32.1 to 168.5.63.254168.5.63.2558,190
43168.5.64.0/19168.5.64.1 to 168.5.95.254168.5.95.2558,190
44168.5.96.0/19168.5.96.1 to 168.5.127.254168.5.127.2558,190
45168.5.128.0/19168.5.128.1 to 168.5.159.254168.5.159.2558,190
46168.5.160.0/19168.5.160.1 to 168.5.191.254168.5.191.2558,190
47168.5.192.0/19168.5.192.1 to 168.5.223.254168.5.223.2558,190
48168.5.224.0/19168.5.224.1 to 168.5.255.254168.5.255.2558,190
49168.6.0.0/19168.6.0.1 to 168.6.31.254168.6.31.2558,190
50168.6.32.0/19168.6.32.1 to 168.6.63.254168.6.63.2558,190
51168.6.64.0/19168.6.64.1 to 168.6.95.254168.6.95.2558,190
52168.6.96.0/19168.6.96.1 to 168.6.127.254168.6.127.2558,190
53168.6.128.0/19168.6.128.1 to 168.6.159.254168.6.159.2558,190
54168.6.160.0/19168.6.160.1 to 168.6.191.254168.6.191.2558,190
55168.6.192.0/19168.6.192.1 to 168.6.223.254168.6.223.2558,190
56168.6.224.0/19168.6.224.1 to 168.6.255.254168.6.255.2558,190
57168.7.0.0/19168.7.0.1 to 168.7.31.254168.7.31.2558,190
58168.7.32.0/19168.7.32.1 to 168.7.63.254168.7.63.2558,190
59168.7.64.0/19168.7.64.1 to 168.7.95.254168.7.95.2558,190
60168.7.96.0/19168.7.96.1 to 168.7.127.254168.7.127.2558,190
61168.7.128.0/19168.7.128.1 to 168.7.159.254168.7.159.2558,190
62168.7.160.0/19168.7.160.1 to 168.7.191.254168.7.191.2558,190
63168.7.192.0/19168.7.192.1 to 168.7.223.254168.7.223.2558,190
64168.7.224.0/19168.7.224.1 to 168.7.255.254168.7.255.2558,190
65168.8.0.0/19168.8.0.1 to 168.8.31.254168.8.31.2558,190
66168.8.32.0/19168.8.32.1 to 168.8.63.254168.8.63.2558,190
67168.8.64.0/19168.8.64.1 to 168.8.95.254168.8.95.2558,190
68168.8.96.0/19168.8.96.1 to 168.8.127.254168.8.127.2558,190
69168.8.128.0/19168.8.128.1 to 168.8.159.254168.8.159.2558,190
70168.8.160.0/19168.8.160.1 to 168.8.191.254168.8.191.2558,190
71168.8.192.0/19168.8.192.1 to 168.8.223.254168.8.223.2558,190
72168.8.224.0/19168.8.224.1 to 168.8.255.254168.8.255.2558,190
73168.9.0.0/19168.9.0.1 to 168.9.31.254168.9.31.2558,190
74168.9.32.0/19168.9.32.1 to 168.9.63.254168.9.63.2558,190
75168.9.64.0/19168.9.64.1 to 168.9.95.254168.9.95.2558,190
76168.9.96.0/19168.9.96.1 to 168.9.127.254168.9.127.2558,190
77168.9.128.0/19168.9.128.1 to 168.9.159.254168.9.159.2558,190
78168.9.160.0/19168.9.160.1 to 168.9.191.254168.9.191.2558,190
79168.9.192.0/19168.9.192.1 to 168.9.223.254168.9.223.2558,190
80168.9.224.0/19168.9.224.1 to 168.9.255.254168.9.255.2558,190
81168.10.0.0/19168.10.0.1 to 168.10.31.254168.10.31.2558,190
82168.10.32.0/19168.10.32.1 to 168.10.63.254168.10.63.2558,190
83168.10.64.0/19168.10.64.1 to 168.10.95.254168.10.95.2558,190
84168.10.96.0/19168.10.96.1 to 168.10.127.254168.10.127.2558,190
85168.10.128.0/19168.10.128.1 to 168.10.159.254168.10.159.2558,190
86168.10.160.0/19168.10.160.1 to 168.10.191.254168.10.191.2558,190
87168.10.192.0/19168.10.192.1 to 168.10.223.254168.10.223.2558,190
88168.10.224.0/19168.10.224.1 to 168.10.255.254168.10.255.2558,190
89168.11.0.0/19168.11.0.1 to 168.11.31.254168.11.31.2558,190
90168.11.32.0/19168.11.32.1 to 168.11.63.254168.11.63.2558,190
91168.11.64.0/19168.11.64.1 to 168.11.95.254168.11.95.2558,190
92168.11.96.0/19168.11.96.1 to 168.11.127.254168.11.127.2558,190
93168.11.128.0/19168.11.128.1 to 168.11.159.254168.11.159.2558,190
94168.11.160.0/19168.11.160.1 to 168.11.191.254168.11.191.2558,190
95168.11.192.0/19168.11.192.1 to 168.11.223.254168.11.223.2558,190
96168.11.224.0/19168.11.224.1 to 168.11.255.254168.11.255.2558,190
97168.12.0.0/19168.12.0.1 to 168.12.31.254168.12.31.2558,190
98168.12.32.0/19168.12.32.1 to 168.12.63.254168.12.63.2558,190
99168.12.64.0/19168.12.64.1 to 168.12.95.254168.12.95.2558,190
100168.12.96.0/19168.12.96.1 to 168.12.127.254168.12.127.2558,190
101168.12.128.0/19168.12.128.1 to 168.12.159.254168.12.159.2558,190
102168.12.160.0/19168.12.160.1 to 168.12.191.254168.12.191.2558,190
103168.12.192.0/19168.12.192.1 to 168.12.223.254168.12.223.2558,190
104168.12.224.0/19168.12.224.1 to 168.12.255.254168.12.255.2558,190
105168.13.0.0/19168.13.0.1 to 168.13.31.254168.13.31.2558,190
106168.13.32.0/19168.13.32.1 to 168.13.63.254168.13.63.2558,190
107168.13.64.0/19168.13.64.1 to 168.13.95.254168.13.95.2558,190
108168.13.96.0/19168.13.96.1 to 168.13.127.254168.13.127.2558,190
109168.13.128.0/19168.13.128.1 to 168.13.159.254168.13.159.2558,190
110168.13.160.0/19168.13.160.1 to 168.13.191.254168.13.191.2558,190
111168.13.192.0/19168.13.192.1 to 168.13.223.254168.13.223.2558,190
112168.13.224.0/19168.13.224.1 to 168.13.255.254168.13.255.2558,190
113168.14.0.0/19168.14.0.1 to 168.14.31.254168.14.31.2558,190
114168.14.32.0/19168.14.32.1 to 168.14.63.254168.14.63.2558,190
115168.14.64.0/19168.14.64.1 to 168.14.95.254168.14.95.2558,190
116168.14.96.0/19168.14.96.1 to 168.14.127.254168.14.127.2558,190
117168.14.128.0/19168.14.128.1 to 168.14.159.254168.14.159.2558,190
118168.14.160.0/19168.14.160.1 to 168.14.191.254168.14.191.2558,190
119168.14.192.0/19168.14.192.1 to 168.14.223.254168.14.223.2558,190
120168.14.224.0/19168.14.224.1 to 168.14.255.254168.14.255.2558,190
121168.15.0.0/19168.15.0.1 to 168.15.31.254168.15.31.2558,190
122168.15.32.0/19168.15.32.1 to 168.15.63.254168.15.63.2558,190
123168.15.64.0/19168.15.64.1 to 168.15.95.254168.15.95.2558,190
124168.15.96.0/19168.15.96.1 to 168.15.127.254168.15.127.2558,190
125168.15.128.0/19168.15.128.1 to 168.15.159.254168.15.159.2558,190
126168.15.160.0/19168.15.160.1 to 168.15.191.254168.15.191.2558,190
127168.15.192.0/19168.15.192.1 to 168.15.223.254168.15.223.2558,190
128168.15.224.0/19168.15.224.1 to 168.15.255.254168.15.255.2558,190
129168.16.0.0/19168.16.0.1 to 168.16.31.254168.16.31.2558,190
130168.16.32.0/19168.16.32.1 to 168.16.63.254168.16.63.2558,190
131168.16.64.0/19168.16.64.1 to 168.16.95.254168.16.95.2558,190
132168.16.96.0/19168.16.96.1 to 168.16.127.254168.16.127.2558,190
133168.16.128.0/19168.16.128.1 to 168.16.159.254168.16.159.2558,190
134168.16.160.0/19168.16.160.1 to 168.16.191.254168.16.191.2558,190
135168.16.192.0/19168.16.192.1 to 168.16.223.254168.16.223.2558,190
136168.16.224.0/19168.16.224.1 to 168.16.255.254168.16.255.2558,190
137168.17.0.0/19168.17.0.1 to 168.17.31.254168.17.31.2558,190
138168.17.32.0/19168.17.32.1 to 168.17.63.254168.17.63.2558,190
139168.17.64.0/19168.17.64.1 to 168.17.95.254168.17.95.2558,190
140168.17.96.0/19168.17.96.1 to 168.17.127.254168.17.127.2558,190
141168.17.128.0/19168.17.128.1 to 168.17.159.254168.17.159.2558,190
142168.17.160.0/19168.17.160.1 to 168.17.191.254168.17.191.2558,190
143168.17.192.0/19168.17.192.1 to 168.17.223.254168.17.223.2558,190
144168.17.224.0/19168.17.224.1 to 168.17.255.254168.17.255.2558,190
145168.18.0.0/19168.18.0.1 to 168.18.31.254168.18.31.2558,190
146168.18.32.0/19168.18.32.1 to 168.18.63.254168.18.63.2558,190
147168.18.64.0/19168.18.64.1 to 168.18.95.254168.18.95.2558,190
148168.18.96.0/19168.18.96.1 to 168.18.127.254168.18.127.2558,190
149168.18.128.0/19168.18.128.1 to 168.18.159.254168.18.159.2558,190
150168.18.160.0/19168.18.160.1 to 168.18.191.254168.18.191.2558,190
151168.18.192.0/19168.18.192.1 to 168.18.223.254168.18.223.2558,190
152168.18.224.0/19168.18.224.1 to 168.18.255.254168.18.255.2558,190
153168.19.0.0/19168.19.0.1 to 168.19.31.254168.19.31.2558,190
154168.19.32.0/19168.19.32.1 to 168.19.63.254168.19.63.2558,190
155168.19.64.0/19168.19.64.1 to 168.19.95.254168.19.95.2558,190
156168.19.96.0/19168.19.96.1 to 168.19.127.254168.19.127.2558,190
157168.19.128.0/19168.19.128.1 to 168.19.159.254168.19.159.2558,190
158168.19.160.0/19168.19.160.1 to 168.19.191.254168.19.191.2558,190
159168.19.192.0/19168.19.192.1 to 168.19.223.254168.19.223.2558,190
160168.19.224.0/19168.19.224.1 to 168.19.255.254168.19.255.2558,190
161168.20.0.0/19168.20.0.1 to 168.20.31.254168.20.31.2558,190
162168.20.32.0/19168.20.32.1 to 168.20.63.254168.20.63.2558,190
163168.20.64.0/19168.20.64.1 to 168.20.95.254168.20.95.2558,190
164168.20.96.0/19168.20.96.1 to 168.20.127.254168.20.127.2558,190
165168.20.128.0/19168.20.128.1 to 168.20.159.254168.20.159.2558,190
166168.20.160.0/19168.20.160.1 to 168.20.191.254168.20.191.2558,190
167168.20.192.0/19168.20.192.1 to 168.20.223.254168.20.223.2558,190
168168.20.224.0/19168.20.224.1 to 168.20.255.254168.20.255.2558,190
169168.21.0.0/19168.21.0.1 to 168.21.31.254168.21.31.2558,190
170168.21.32.0/19168.21.32.1 to 168.21.63.254168.21.63.2558,190
171168.21.64.0/19168.21.64.1 to 168.21.95.254168.21.95.2558,190
172168.21.96.0/19168.21.96.1 to 168.21.127.254168.21.127.2558,190
173168.21.128.0/19168.21.128.1 to 168.21.159.254168.21.159.2558,190
174168.21.160.0/19168.21.160.1 to 168.21.191.254168.21.191.2558,190
175168.21.192.0/19168.21.192.1 to 168.21.223.254168.21.223.2558,190
176168.21.224.0/19168.21.224.1 to 168.21.255.254168.21.255.2558,190
177168.22.0.0/19168.22.0.1 to 168.22.31.254168.22.31.2558,190
178168.22.32.0/19168.22.32.1 to 168.22.63.254168.22.63.2558,190
179168.22.64.0/19168.22.64.1 to 168.22.95.254168.22.95.2558,190
180168.22.96.0/19168.22.96.1 to 168.22.127.254168.22.127.2558,190
181168.22.128.0/19168.22.128.1 to 168.22.159.254168.22.159.2558,190
182168.22.160.0/19168.22.160.1 to 168.22.191.254168.22.191.2558,190
183168.22.192.0/19168.22.192.1 to 168.22.223.254168.22.223.2558,190
184168.22.224.0/19168.22.224.1 to 168.22.255.254168.22.255.2558,190
185168.23.0.0/19168.23.0.1 to 168.23.31.254168.23.31.2558,190
186168.23.32.0/19168.23.32.1 to 168.23.63.254168.23.63.2558,190
187168.23.64.0/19168.23.64.1 to 168.23.95.254168.23.95.2558,190
188168.23.96.0/19168.23.96.1 to 168.23.127.254168.23.127.2558,190
189168.23.128.0/19168.23.128.1 to 168.23.159.254168.23.159.2558,190
190168.23.160.0/19168.23.160.1 to 168.23.191.254168.23.191.2558,190
191168.23.192.0/19168.23.192.1 to 168.23.223.254168.23.223.2558,190
192168.23.224.0/19168.23.224.1 to 168.23.255.254168.23.255.2558,190
193168.24.0.0/19168.24.0.1 to 168.24.31.254168.24.31.2558,190
194168.24.32.0/19168.24.32.1 to 168.24.63.254168.24.63.2558,190
195168.24.64.0/19168.24.64.1 to 168.24.95.254168.24.95.2558,190
196168.24.96.0/19168.24.96.1 to 168.24.127.254168.24.127.2558,190
197168.24.128.0/19168.24.128.1 to 168.24.159.254168.24.159.2558,190
198168.24.160.0/19168.24.160.1 to 168.24.191.254168.24.191.2558,190
199168.24.192.0/19168.24.192.1 to 168.24.223.254168.24.223.2558,190
200168.24.224.0/19168.24.224.1 to 168.24.255.254168.24.255.2558,190
201168.25.0.0/19168.25.0.1 to 168.25.31.254168.25.31.2558,190
202168.25.32.0/19168.25.32.1 to 168.25.63.254168.25.63.2558,190
203168.25.64.0/19168.25.64.1 to 168.25.95.254168.25.95.2558,190
204168.25.96.0/19168.25.96.1 to 168.25.127.254168.25.127.2558,190
205168.25.128.0/19168.25.128.1 to 168.25.159.254168.25.159.2558,190
206168.25.160.0/19168.25.160.1 to 168.25.191.254168.25.191.2558,190
207168.25.192.0/19168.25.192.1 to 168.25.223.254168.25.223.2558,190
208168.25.224.0/19168.25.224.1 to 168.25.255.254168.25.255.2558,190
209168.26.0.0/19168.26.0.1 to 168.26.31.254168.26.31.2558,190
210168.26.32.0/19168.26.32.1 to 168.26.63.254168.26.63.2558,190
211168.26.64.0/19168.26.64.1 to 168.26.95.254168.26.95.2558,190
212168.26.96.0/19168.26.96.1 to 168.26.127.254168.26.127.2558,190
213168.26.128.0/19168.26.128.1 to 168.26.159.254168.26.159.2558,190
214168.26.160.0/19168.26.160.1 to 168.26.191.254168.26.191.2558,190
215168.26.192.0/19168.26.192.1 to 168.26.223.254168.26.223.2558,190
216168.26.224.0/19168.26.224.1 to 168.26.255.254168.26.255.2558,190
217168.27.0.0/19168.27.0.1 to 168.27.31.254168.27.31.2558,190
218168.27.32.0/19168.27.32.1 to 168.27.63.254168.27.63.2558,190
219168.27.64.0/19168.27.64.1 to 168.27.95.254168.27.95.2558,190
220168.27.96.0/19168.27.96.1 to 168.27.127.254168.27.127.2558,190
221168.27.128.0/19168.27.128.1 to 168.27.159.254168.27.159.2558,190
222168.27.160.0/19168.27.160.1 to 168.27.191.254168.27.191.2558,190
223168.27.192.0/19168.27.192.1 to 168.27.223.254168.27.223.2558,190
224168.27.224.0/19168.27.224.1 to 168.27.255.254168.27.255.2558,190
225168.28.0.0/19168.28.0.1 to 168.28.31.254168.28.31.2558,190
226168.28.32.0/19168.28.32.1 to 168.28.63.254168.28.63.2558,190
227168.28.64.0/19168.28.64.1 to 168.28.95.254168.28.95.2558,190
228168.28.96.0/19168.28.96.1 to 168.28.127.254168.28.127.2558,190
229168.28.128.0/19168.28.128.1 to 168.28.159.254168.28.159.2558,190
230168.28.160.0/19168.28.160.1 to 168.28.191.254168.28.191.2558,190
231168.28.192.0/19168.28.192.1 to 168.28.223.254168.28.223.2558,190
232168.28.224.0/19168.28.224.1 to 168.28.255.254168.28.255.2558,190
233168.29.0.0/19168.29.0.1 to 168.29.31.254168.29.31.2558,190
234168.29.32.0/19168.29.32.1 to 168.29.63.254168.29.63.2558,190
235168.29.64.0/19168.29.64.1 to 168.29.95.254168.29.95.2558,190
236168.29.96.0/19168.29.96.1 to 168.29.127.254168.29.127.2558,190
237168.29.128.0/19168.29.128.1 to 168.29.159.254168.29.159.2558,190
238168.29.160.0/19168.29.160.1 to 168.29.191.254168.29.191.2558,190
239168.29.192.0/19168.29.192.1 to 168.29.223.254168.29.223.2558,190
240168.29.224.0/19168.29.224.1 to 168.29.255.254168.29.255.2558,190
241168.30.0.0/19168.30.0.1 to 168.30.31.254168.30.31.2558,190
242168.30.32.0/19168.30.32.1 to 168.30.63.254168.30.63.2558,190
243168.30.64.0/19168.30.64.1 to 168.30.95.254168.30.95.2558,190
244168.30.96.0/19168.30.96.1 to 168.30.127.254168.30.127.2558,190
245168.30.128.0/19168.30.128.1 to 168.30.159.254168.30.159.2558,190
246168.30.160.0/19168.30.160.1 to 168.30.191.254168.30.191.2558,190
247168.30.192.0/19168.30.192.1 to 168.30.223.254168.30.223.2558,190
248168.30.224.0/19168.30.224.1 to 168.30.255.254168.30.255.2558,190
249168.31.0.0/19168.31.0.1 to 168.31.31.254168.31.31.2558,190
250168.31.32.0/19168.31.32.1 to 168.31.63.254168.31.63.2558,190
251168.31.64.0/19168.31.64.1 to 168.31.95.254168.31.95.2558,190
252168.31.96.0/19168.31.96.1 to 168.31.127.254168.31.127.2558,190
253168.31.128.0/19168.31.128.1 to 168.31.159.254168.31.159.2558,190
254168.31.160.0/19168.31.160.1 to 168.31.191.254168.31.191.2558,190
255168.31.192.0/19168.31.192.1 to 168.31.223.254168.31.223.2558,190
256168.31.224.0/19168.31.224.1 to 168.31.255.254168.31.255.2558,190

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.