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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.

Network173.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
173.0.0.0
Broadcast address
173.255.255.255
First usable
173.0.0.1
Last usable
173.255.255.254
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 AD000000 · Integer 2902458368 to 2919235583
Reverse DNS zone
173.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10101101..00000000.00000000.00000000173.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network10101101..00000000.00000000.00000000173.0.0.0
Broadcast10101101..11111111.11111111.11111111173.255.255.255
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)

173.0.0.0/8 makes 2,048 subnets of /19; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1173.0.0.0/19173.0.0.1 to 173.0.31.254173.0.31.2558,190
2173.0.32.0/19173.0.32.1 to 173.0.63.254173.0.63.2558,190
3173.0.64.0/19173.0.64.1 to 173.0.95.254173.0.95.2558,190
4173.0.96.0/19173.0.96.1 to 173.0.127.254173.0.127.2558,190
5173.0.128.0/19173.0.128.1 to 173.0.159.254173.0.159.2558,190
6173.0.160.0/19173.0.160.1 to 173.0.191.254173.0.191.2558,190
7173.0.192.0/19173.0.192.1 to 173.0.223.254173.0.223.2558,190
8173.0.224.0/19173.0.224.1 to 173.0.255.254173.0.255.2558,190
9173.1.0.0/19173.1.0.1 to 173.1.31.254173.1.31.2558,190
10173.1.32.0/19173.1.32.1 to 173.1.63.254173.1.63.2558,190
11173.1.64.0/19173.1.64.1 to 173.1.95.254173.1.95.2558,190
12173.1.96.0/19173.1.96.1 to 173.1.127.254173.1.127.2558,190
13173.1.128.0/19173.1.128.1 to 173.1.159.254173.1.159.2558,190
14173.1.160.0/19173.1.160.1 to 173.1.191.254173.1.191.2558,190
15173.1.192.0/19173.1.192.1 to 173.1.223.254173.1.223.2558,190
16173.1.224.0/19173.1.224.1 to 173.1.255.254173.1.255.2558,190
17173.2.0.0/19173.2.0.1 to 173.2.31.254173.2.31.2558,190
18173.2.32.0/19173.2.32.1 to 173.2.63.254173.2.63.2558,190
19173.2.64.0/19173.2.64.1 to 173.2.95.254173.2.95.2558,190
20173.2.96.0/19173.2.96.1 to 173.2.127.254173.2.127.2558,190
21173.2.128.0/19173.2.128.1 to 173.2.159.254173.2.159.2558,190
22173.2.160.0/19173.2.160.1 to 173.2.191.254173.2.191.2558,190
23173.2.192.0/19173.2.192.1 to 173.2.223.254173.2.223.2558,190
24173.2.224.0/19173.2.224.1 to 173.2.255.254173.2.255.2558,190
25173.3.0.0/19173.3.0.1 to 173.3.31.254173.3.31.2558,190
26173.3.32.0/19173.3.32.1 to 173.3.63.254173.3.63.2558,190
27173.3.64.0/19173.3.64.1 to 173.3.95.254173.3.95.2558,190
28173.3.96.0/19173.3.96.1 to 173.3.127.254173.3.127.2558,190
29173.3.128.0/19173.3.128.1 to 173.3.159.254173.3.159.2558,190
30173.3.160.0/19173.3.160.1 to 173.3.191.254173.3.191.2558,190
31173.3.192.0/19173.3.192.1 to 173.3.223.254173.3.223.2558,190
32173.3.224.0/19173.3.224.1 to 173.3.255.254173.3.255.2558,190
33173.4.0.0/19173.4.0.1 to 173.4.31.254173.4.31.2558,190
34173.4.32.0/19173.4.32.1 to 173.4.63.254173.4.63.2558,190
35173.4.64.0/19173.4.64.1 to 173.4.95.254173.4.95.2558,190
36173.4.96.0/19173.4.96.1 to 173.4.127.254173.4.127.2558,190
37173.4.128.0/19173.4.128.1 to 173.4.159.254173.4.159.2558,190
38173.4.160.0/19173.4.160.1 to 173.4.191.254173.4.191.2558,190
39173.4.192.0/19173.4.192.1 to 173.4.223.254173.4.223.2558,190
40173.4.224.0/19173.4.224.1 to 173.4.255.254173.4.255.2558,190
41173.5.0.0/19173.5.0.1 to 173.5.31.254173.5.31.2558,190
42173.5.32.0/19173.5.32.1 to 173.5.63.254173.5.63.2558,190
43173.5.64.0/19173.5.64.1 to 173.5.95.254173.5.95.2558,190
44173.5.96.0/19173.5.96.1 to 173.5.127.254173.5.127.2558,190
45173.5.128.0/19173.5.128.1 to 173.5.159.254173.5.159.2558,190
46173.5.160.0/19173.5.160.1 to 173.5.191.254173.5.191.2558,190
47173.5.192.0/19173.5.192.1 to 173.5.223.254173.5.223.2558,190
48173.5.224.0/19173.5.224.1 to 173.5.255.254173.5.255.2558,190
49173.6.0.0/19173.6.0.1 to 173.6.31.254173.6.31.2558,190
50173.6.32.0/19173.6.32.1 to 173.6.63.254173.6.63.2558,190
51173.6.64.0/19173.6.64.1 to 173.6.95.254173.6.95.2558,190
52173.6.96.0/19173.6.96.1 to 173.6.127.254173.6.127.2558,190
53173.6.128.0/19173.6.128.1 to 173.6.159.254173.6.159.2558,190
54173.6.160.0/19173.6.160.1 to 173.6.191.254173.6.191.2558,190
55173.6.192.0/19173.6.192.1 to 173.6.223.254173.6.223.2558,190
56173.6.224.0/19173.6.224.1 to 173.6.255.254173.6.255.2558,190
57173.7.0.0/19173.7.0.1 to 173.7.31.254173.7.31.2558,190
58173.7.32.0/19173.7.32.1 to 173.7.63.254173.7.63.2558,190
59173.7.64.0/19173.7.64.1 to 173.7.95.254173.7.95.2558,190
60173.7.96.0/19173.7.96.1 to 173.7.127.254173.7.127.2558,190
61173.7.128.0/19173.7.128.1 to 173.7.159.254173.7.159.2558,190
62173.7.160.0/19173.7.160.1 to 173.7.191.254173.7.191.2558,190
63173.7.192.0/19173.7.192.1 to 173.7.223.254173.7.223.2558,190
64173.7.224.0/19173.7.224.1 to 173.7.255.254173.7.255.2558,190
65173.8.0.0/19173.8.0.1 to 173.8.31.254173.8.31.2558,190
66173.8.32.0/19173.8.32.1 to 173.8.63.254173.8.63.2558,190
67173.8.64.0/19173.8.64.1 to 173.8.95.254173.8.95.2558,190
68173.8.96.0/19173.8.96.1 to 173.8.127.254173.8.127.2558,190
69173.8.128.0/19173.8.128.1 to 173.8.159.254173.8.159.2558,190
70173.8.160.0/19173.8.160.1 to 173.8.191.254173.8.191.2558,190
71173.8.192.0/19173.8.192.1 to 173.8.223.254173.8.223.2558,190
72173.8.224.0/19173.8.224.1 to 173.8.255.254173.8.255.2558,190
73173.9.0.0/19173.9.0.1 to 173.9.31.254173.9.31.2558,190
74173.9.32.0/19173.9.32.1 to 173.9.63.254173.9.63.2558,190
75173.9.64.0/19173.9.64.1 to 173.9.95.254173.9.95.2558,190
76173.9.96.0/19173.9.96.1 to 173.9.127.254173.9.127.2558,190
77173.9.128.0/19173.9.128.1 to 173.9.159.254173.9.159.2558,190
78173.9.160.0/19173.9.160.1 to 173.9.191.254173.9.191.2558,190
79173.9.192.0/19173.9.192.1 to 173.9.223.254173.9.223.2558,190
80173.9.224.0/19173.9.224.1 to 173.9.255.254173.9.255.2558,190
81173.10.0.0/19173.10.0.1 to 173.10.31.254173.10.31.2558,190
82173.10.32.0/19173.10.32.1 to 173.10.63.254173.10.63.2558,190
83173.10.64.0/19173.10.64.1 to 173.10.95.254173.10.95.2558,190
84173.10.96.0/19173.10.96.1 to 173.10.127.254173.10.127.2558,190
85173.10.128.0/19173.10.128.1 to 173.10.159.254173.10.159.2558,190
86173.10.160.0/19173.10.160.1 to 173.10.191.254173.10.191.2558,190
87173.10.192.0/19173.10.192.1 to 173.10.223.254173.10.223.2558,190
88173.10.224.0/19173.10.224.1 to 173.10.255.254173.10.255.2558,190
89173.11.0.0/19173.11.0.1 to 173.11.31.254173.11.31.2558,190
90173.11.32.0/19173.11.32.1 to 173.11.63.254173.11.63.2558,190
91173.11.64.0/19173.11.64.1 to 173.11.95.254173.11.95.2558,190
92173.11.96.0/19173.11.96.1 to 173.11.127.254173.11.127.2558,190
93173.11.128.0/19173.11.128.1 to 173.11.159.254173.11.159.2558,190
94173.11.160.0/19173.11.160.1 to 173.11.191.254173.11.191.2558,190
95173.11.192.0/19173.11.192.1 to 173.11.223.254173.11.223.2558,190
96173.11.224.0/19173.11.224.1 to 173.11.255.254173.11.255.2558,190
97173.12.0.0/19173.12.0.1 to 173.12.31.254173.12.31.2558,190
98173.12.32.0/19173.12.32.1 to 173.12.63.254173.12.63.2558,190
99173.12.64.0/19173.12.64.1 to 173.12.95.254173.12.95.2558,190
100173.12.96.0/19173.12.96.1 to 173.12.127.254173.12.127.2558,190
101173.12.128.0/19173.12.128.1 to 173.12.159.254173.12.159.2558,190
102173.12.160.0/19173.12.160.1 to 173.12.191.254173.12.191.2558,190
103173.12.192.0/19173.12.192.1 to 173.12.223.254173.12.223.2558,190
104173.12.224.0/19173.12.224.1 to 173.12.255.254173.12.255.2558,190
105173.13.0.0/19173.13.0.1 to 173.13.31.254173.13.31.2558,190
106173.13.32.0/19173.13.32.1 to 173.13.63.254173.13.63.2558,190
107173.13.64.0/19173.13.64.1 to 173.13.95.254173.13.95.2558,190
108173.13.96.0/19173.13.96.1 to 173.13.127.254173.13.127.2558,190
109173.13.128.0/19173.13.128.1 to 173.13.159.254173.13.159.2558,190
110173.13.160.0/19173.13.160.1 to 173.13.191.254173.13.191.2558,190
111173.13.192.0/19173.13.192.1 to 173.13.223.254173.13.223.2558,190
112173.13.224.0/19173.13.224.1 to 173.13.255.254173.13.255.2558,190
113173.14.0.0/19173.14.0.1 to 173.14.31.254173.14.31.2558,190
114173.14.32.0/19173.14.32.1 to 173.14.63.254173.14.63.2558,190
115173.14.64.0/19173.14.64.1 to 173.14.95.254173.14.95.2558,190
116173.14.96.0/19173.14.96.1 to 173.14.127.254173.14.127.2558,190
117173.14.128.0/19173.14.128.1 to 173.14.159.254173.14.159.2558,190
118173.14.160.0/19173.14.160.1 to 173.14.191.254173.14.191.2558,190
119173.14.192.0/19173.14.192.1 to 173.14.223.254173.14.223.2558,190
120173.14.224.0/19173.14.224.1 to 173.14.255.254173.14.255.2558,190
121173.15.0.0/19173.15.0.1 to 173.15.31.254173.15.31.2558,190
122173.15.32.0/19173.15.32.1 to 173.15.63.254173.15.63.2558,190
123173.15.64.0/19173.15.64.1 to 173.15.95.254173.15.95.2558,190
124173.15.96.0/19173.15.96.1 to 173.15.127.254173.15.127.2558,190
125173.15.128.0/19173.15.128.1 to 173.15.159.254173.15.159.2558,190
126173.15.160.0/19173.15.160.1 to 173.15.191.254173.15.191.2558,190
127173.15.192.0/19173.15.192.1 to 173.15.223.254173.15.223.2558,190
128173.15.224.0/19173.15.224.1 to 173.15.255.254173.15.255.2558,190
129173.16.0.0/19173.16.0.1 to 173.16.31.254173.16.31.2558,190
130173.16.32.0/19173.16.32.1 to 173.16.63.254173.16.63.2558,190
131173.16.64.0/19173.16.64.1 to 173.16.95.254173.16.95.2558,190
132173.16.96.0/19173.16.96.1 to 173.16.127.254173.16.127.2558,190
133173.16.128.0/19173.16.128.1 to 173.16.159.254173.16.159.2558,190
134173.16.160.0/19173.16.160.1 to 173.16.191.254173.16.191.2558,190
135173.16.192.0/19173.16.192.1 to 173.16.223.254173.16.223.2558,190
136173.16.224.0/19173.16.224.1 to 173.16.255.254173.16.255.2558,190
137173.17.0.0/19173.17.0.1 to 173.17.31.254173.17.31.2558,190
138173.17.32.0/19173.17.32.1 to 173.17.63.254173.17.63.2558,190
139173.17.64.0/19173.17.64.1 to 173.17.95.254173.17.95.2558,190
140173.17.96.0/19173.17.96.1 to 173.17.127.254173.17.127.2558,190
141173.17.128.0/19173.17.128.1 to 173.17.159.254173.17.159.2558,190
142173.17.160.0/19173.17.160.1 to 173.17.191.254173.17.191.2558,190
143173.17.192.0/19173.17.192.1 to 173.17.223.254173.17.223.2558,190
144173.17.224.0/19173.17.224.1 to 173.17.255.254173.17.255.2558,190
145173.18.0.0/19173.18.0.1 to 173.18.31.254173.18.31.2558,190
146173.18.32.0/19173.18.32.1 to 173.18.63.254173.18.63.2558,190
147173.18.64.0/19173.18.64.1 to 173.18.95.254173.18.95.2558,190
148173.18.96.0/19173.18.96.1 to 173.18.127.254173.18.127.2558,190
149173.18.128.0/19173.18.128.1 to 173.18.159.254173.18.159.2558,190
150173.18.160.0/19173.18.160.1 to 173.18.191.254173.18.191.2558,190
151173.18.192.0/19173.18.192.1 to 173.18.223.254173.18.223.2558,190
152173.18.224.0/19173.18.224.1 to 173.18.255.254173.18.255.2558,190
153173.19.0.0/19173.19.0.1 to 173.19.31.254173.19.31.2558,190
154173.19.32.0/19173.19.32.1 to 173.19.63.254173.19.63.2558,190
155173.19.64.0/19173.19.64.1 to 173.19.95.254173.19.95.2558,190
156173.19.96.0/19173.19.96.1 to 173.19.127.254173.19.127.2558,190
157173.19.128.0/19173.19.128.1 to 173.19.159.254173.19.159.2558,190
158173.19.160.0/19173.19.160.1 to 173.19.191.254173.19.191.2558,190
159173.19.192.0/19173.19.192.1 to 173.19.223.254173.19.223.2558,190
160173.19.224.0/19173.19.224.1 to 173.19.255.254173.19.255.2558,190
161173.20.0.0/19173.20.0.1 to 173.20.31.254173.20.31.2558,190
162173.20.32.0/19173.20.32.1 to 173.20.63.254173.20.63.2558,190
163173.20.64.0/19173.20.64.1 to 173.20.95.254173.20.95.2558,190
164173.20.96.0/19173.20.96.1 to 173.20.127.254173.20.127.2558,190
165173.20.128.0/19173.20.128.1 to 173.20.159.254173.20.159.2558,190
166173.20.160.0/19173.20.160.1 to 173.20.191.254173.20.191.2558,190
167173.20.192.0/19173.20.192.1 to 173.20.223.254173.20.223.2558,190
168173.20.224.0/19173.20.224.1 to 173.20.255.254173.20.255.2558,190
169173.21.0.0/19173.21.0.1 to 173.21.31.254173.21.31.2558,190
170173.21.32.0/19173.21.32.1 to 173.21.63.254173.21.63.2558,190
171173.21.64.0/19173.21.64.1 to 173.21.95.254173.21.95.2558,190
172173.21.96.0/19173.21.96.1 to 173.21.127.254173.21.127.2558,190
173173.21.128.0/19173.21.128.1 to 173.21.159.254173.21.159.2558,190
174173.21.160.0/19173.21.160.1 to 173.21.191.254173.21.191.2558,190
175173.21.192.0/19173.21.192.1 to 173.21.223.254173.21.223.2558,190
176173.21.224.0/19173.21.224.1 to 173.21.255.254173.21.255.2558,190
177173.22.0.0/19173.22.0.1 to 173.22.31.254173.22.31.2558,190
178173.22.32.0/19173.22.32.1 to 173.22.63.254173.22.63.2558,190
179173.22.64.0/19173.22.64.1 to 173.22.95.254173.22.95.2558,190
180173.22.96.0/19173.22.96.1 to 173.22.127.254173.22.127.2558,190
181173.22.128.0/19173.22.128.1 to 173.22.159.254173.22.159.2558,190
182173.22.160.0/19173.22.160.1 to 173.22.191.254173.22.191.2558,190
183173.22.192.0/19173.22.192.1 to 173.22.223.254173.22.223.2558,190
184173.22.224.0/19173.22.224.1 to 173.22.255.254173.22.255.2558,190
185173.23.0.0/19173.23.0.1 to 173.23.31.254173.23.31.2558,190
186173.23.32.0/19173.23.32.1 to 173.23.63.254173.23.63.2558,190
187173.23.64.0/19173.23.64.1 to 173.23.95.254173.23.95.2558,190
188173.23.96.0/19173.23.96.1 to 173.23.127.254173.23.127.2558,190
189173.23.128.0/19173.23.128.1 to 173.23.159.254173.23.159.2558,190
190173.23.160.0/19173.23.160.1 to 173.23.191.254173.23.191.2558,190
191173.23.192.0/19173.23.192.1 to 173.23.223.254173.23.223.2558,190
192173.23.224.0/19173.23.224.1 to 173.23.255.254173.23.255.2558,190
193173.24.0.0/19173.24.0.1 to 173.24.31.254173.24.31.2558,190
194173.24.32.0/19173.24.32.1 to 173.24.63.254173.24.63.2558,190
195173.24.64.0/19173.24.64.1 to 173.24.95.254173.24.95.2558,190
196173.24.96.0/19173.24.96.1 to 173.24.127.254173.24.127.2558,190
197173.24.128.0/19173.24.128.1 to 173.24.159.254173.24.159.2558,190
198173.24.160.0/19173.24.160.1 to 173.24.191.254173.24.191.2558,190
199173.24.192.0/19173.24.192.1 to 173.24.223.254173.24.223.2558,190
200173.24.224.0/19173.24.224.1 to 173.24.255.254173.24.255.2558,190
201173.25.0.0/19173.25.0.1 to 173.25.31.254173.25.31.2558,190
202173.25.32.0/19173.25.32.1 to 173.25.63.254173.25.63.2558,190
203173.25.64.0/19173.25.64.1 to 173.25.95.254173.25.95.2558,190
204173.25.96.0/19173.25.96.1 to 173.25.127.254173.25.127.2558,190
205173.25.128.0/19173.25.128.1 to 173.25.159.254173.25.159.2558,190
206173.25.160.0/19173.25.160.1 to 173.25.191.254173.25.191.2558,190
207173.25.192.0/19173.25.192.1 to 173.25.223.254173.25.223.2558,190
208173.25.224.0/19173.25.224.1 to 173.25.255.254173.25.255.2558,190
209173.26.0.0/19173.26.0.1 to 173.26.31.254173.26.31.2558,190
210173.26.32.0/19173.26.32.1 to 173.26.63.254173.26.63.2558,190
211173.26.64.0/19173.26.64.1 to 173.26.95.254173.26.95.2558,190
212173.26.96.0/19173.26.96.1 to 173.26.127.254173.26.127.2558,190
213173.26.128.0/19173.26.128.1 to 173.26.159.254173.26.159.2558,190
214173.26.160.0/19173.26.160.1 to 173.26.191.254173.26.191.2558,190
215173.26.192.0/19173.26.192.1 to 173.26.223.254173.26.223.2558,190
216173.26.224.0/19173.26.224.1 to 173.26.255.254173.26.255.2558,190
217173.27.0.0/19173.27.0.1 to 173.27.31.254173.27.31.2558,190
218173.27.32.0/19173.27.32.1 to 173.27.63.254173.27.63.2558,190
219173.27.64.0/19173.27.64.1 to 173.27.95.254173.27.95.2558,190
220173.27.96.0/19173.27.96.1 to 173.27.127.254173.27.127.2558,190
221173.27.128.0/19173.27.128.1 to 173.27.159.254173.27.159.2558,190
222173.27.160.0/19173.27.160.1 to 173.27.191.254173.27.191.2558,190
223173.27.192.0/19173.27.192.1 to 173.27.223.254173.27.223.2558,190
224173.27.224.0/19173.27.224.1 to 173.27.255.254173.27.255.2558,190
225173.28.0.0/19173.28.0.1 to 173.28.31.254173.28.31.2558,190
226173.28.32.0/19173.28.32.1 to 173.28.63.254173.28.63.2558,190
227173.28.64.0/19173.28.64.1 to 173.28.95.254173.28.95.2558,190
228173.28.96.0/19173.28.96.1 to 173.28.127.254173.28.127.2558,190
229173.28.128.0/19173.28.128.1 to 173.28.159.254173.28.159.2558,190
230173.28.160.0/19173.28.160.1 to 173.28.191.254173.28.191.2558,190
231173.28.192.0/19173.28.192.1 to 173.28.223.254173.28.223.2558,190
232173.28.224.0/19173.28.224.1 to 173.28.255.254173.28.255.2558,190
233173.29.0.0/19173.29.0.1 to 173.29.31.254173.29.31.2558,190
234173.29.32.0/19173.29.32.1 to 173.29.63.254173.29.63.2558,190
235173.29.64.0/19173.29.64.1 to 173.29.95.254173.29.95.2558,190
236173.29.96.0/19173.29.96.1 to 173.29.127.254173.29.127.2558,190
237173.29.128.0/19173.29.128.1 to 173.29.159.254173.29.159.2558,190
238173.29.160.0/19173.29.160.1 to 173.29.191.254173.29.191.2558,190
239173.29.192.0/19173.29.192.1 to 173.29.223.254173.29.223.2558,190
240173.29.224.0/19173.29.224.1 to 173.29.255.254173.29.255.2558,190
241173.30.0.0/19173.30.0.1 to 173.30.31.254173.30.31.2558,190
242173.30.32.0/19173.30.32.1 to 173.30.63.254173.30.63.2558,190
243173.30.64.0/19173.30.64.1 to 173.30.95.254173.30.95.2558,190
244173.30.96.0/19173.30.96.1 to 173.30.127.254173.30.127.2558,190
245173.30.128.0/19173.30.128.1 to 173.30.159.254173.30.159.2558,190
246173.30.160.0/19173.30.160.1 to 173.30.191.254173.30.191.2558,190
247173.30.192.0/19173.30.192.1 to 173.30.223.254173.30.223.2558,190
248173.30.224.0/19173.30.224.1 to 173.30.255.254173.30.255.2558,190
249173.31.0.0/19173.31.0.1 to 173.31.31.254173.31.31.2558,190
250173.31.32.0/19173.31.32.1 to 173.31.63.254173.31.63.2558,190
251173.31.64.0/19173.31.64.1 to 173.31.95.254173.31.95.2558,190
252173.31.96.0/19173.31.96.1 to 173.31.127.254173.31.127.2558,190
253173.31.128.0/19173.31.128.1 to 173.31.159.254173.31.159.2558,190
254173.31.160.0/19173.31.160.1 to 173.31.191.254173.31.191.2558,190
255173.31.192.0/19173.31.192.1 to 173.31.223.254173.31.223.2558,190
256173.31.224.0/19173.31.224.1 to 173.31.255.254173.31.255.2558,190

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.