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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.

Network173.0.0.0/12
Usable hosts1,048,574
Subnet mask255.240.0.0
Addresses1,048,576
Network address
173.0.0.0
Broadcast address
173.15.255.255
First usable
173.0.0.1
Last usable
173.15.255.254
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 AD000000 · Integer 2902458368 to 2903506943
Reverse DNS zones
0.173.in-addr.arpa
1.173.in-addr.arpa
2.173.in-addr.arpa
3.173.in-addr.arpa
4.173.in-addr.arpa
5.173.in-addr.arpa
6.173.in-addr.arpa
7.173.in-addr.arpa
8.173.in-addr.arpa
9.173.in-addr.arpa
10.173.in-addr.arpa
11.173.in-addr.arpa
12.173.in-addr.arpa
13.173.in-addr.arpa
14.173.in-addr.arpa
15.173.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
Address10101101.00000000.00000000.00000000173.0.0.0
Subnet mask11111111.11110000.00000000.00000000255.240.0.0
Network10101101.00000000.00000000.00000000173.0.0.0
Broadcast10101101.00001111.11111111.11111111173.15.255.255
Split into smaller subnets/20
/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)

173.0.0.0/12 makes 256 subnets of /20.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1173.0.0.0/20173.0.0.1 to 173.0.15.254173.0.15.2554,094
2173.0.16.0/20173.0.16.1 to 173.0.31.254173.0.31.2554,094
3173.0.32.0/20173.0.32.1 to 173.0.47.254173.0.47.2554,094
4173.0.48.0/20173.0.48.1 to 173.0.63.254173.0.63.2554,094
5173.0.64.0/20173.0.64.1 to 173.0.79.254173.0.79.2554,094
6173.0.80.0/20173.0.80.1 to 173.0.95.254173.0.95.2554,094
7173.0.96.0/20173.0.96.1 to 173.0.111.254173.0.111.2554,094
8173.0.112.0/20173.0.112.1 to 173.0.127.254173.0.127.2554,094
9173.0.128.0/20173.0.128.1 to 173.0.143.254173.0.143.2554,094
10173.0.144.0/20173.0.144.1 to 173.0.159.254173.0.159.2554,094
11173.0.160.0/20173.0.160.1 to 173.0.175.254173.0.175.2554,094
12173.0.176.0/20173.0.176.1 to 173.0.191.254173.0.191.2554,094
13173.0.192.0/20173.0.192.1 to 173.0.207.254173.0.207.2554,094
14173.0.208.0/20173.0.208.1 to 173.0.223.254173.0.223.2554,094
15173.0.224.0/20173.0.224.1 to 173.0.239.254173.0.239.2554,094
16173.0.240.0/20173.0.240.1 to 173.0.255.254173.0.255.2554,094
17173.1.0.0/20173.1.0.1 to 173.1.15.254173.1.15.2554,094
18173.1.16.0/20173.1.16.1 to 173.1.31.254173.1.31.2554,094
19173.1.32.0/20173.1.32.1 to 173.1.47.254173.1.47.2554,094
20173.1.48.0/20173.1.48.1 to 173.1.63.254173.1.63.2554,094
21173.1.64.0/20173.1.64.1 to 173.1.79.254173.1.79.2554,094
22173.1.80.0/20173.1.80.1 to 173.1.95.254173.1.95.2554,094
23173.1.96.0/20173.1.96.1 to 173.1.111.254173.1.111.2554,094
24173.1.112.0/20173.1.112.1 to 173.1.127.254173.1.127.2554,094
25173.1.128.0/20173.1.128.1 to 173.1.143.254173.1.143.2554,094
26173.1.144.0/20173.1.144.1 to 173.1.159.254173.1.159.2554,094
27173.1.160.0/20173.1.160.1 to 173.1.175.254173.1.175.2554,094
28173.1.176.0/20173.1.176.1 to 173.1.191.254173.1.191.2554,094
29173.1.192.0/20173.1.192.1 to 173.1.207.254173.1.207.2554,094
30173.1.208.0/20173.1.208.1 to 173.1.223.254173.1.223.2554,094
31173.1.224.0/20173.1.224.1 to 173.1.239.254173.1.239.2554,094
32173.1.240.0/20173.1.240.1 to 173.1.255.254173.1.255.2554,094
33173.2.0.0/20173.2.0.1 to 173.2.15.254173.2.15.2554,094
34173.2.16.0/20173.2.16.1 to 173.2.31.254173.2.31.2554,094
35173.2.32.0/20173.2.32.1 to 173.2.47.254173.2.47.2554,094
36173.2.48.0/20173.2.48.1 to 173.2.63.254173.2.63.2554,094
37173.2.64.0/20173.2.64.1 to 173.2.79.254173.2.79.2554,094
38173.2.80.0/20173.2.80.1 to 173.2.95.254173.2.95.2554,094
39173.2.96.0/20173.2.96.1 to 173.2.111.254173.2.111.2554,094
40173.2.112.0/20173.2.112.1 to 173.2.127.254173.2.127.2554,094
41173.2.128.0/20173.2.128.1 to 173.2.143.254173.2.143.2554,094
42173.2.144.0/20173.2.144.1 to 173.2.159.254173.2.159.2554,094
43173.2.160.0/20173.2.160.1 to 173.2.175.254173.2.175.2554,094
44173.2.176.0/20173.2.176.1 to 173.2.191.254173.2.191.2554,094
45173.2.192.0/20173.2.192.1 to 173.2.207.254173.2.207.2554,094
46173.2.208.0/20173.2.208.1 to 173.2.223.254173.2.223.2554,094
47173.2.224.0/20173.2.224.1 to 173.2.239.254173.2.239.2554,094
48173.2.240.0/20173.2.240.1 to 173.2.255.254173.2.255.2554,094
49173.3.0.0/20173.3.0.1 to 173.3.15.254173.3.15.2554,094
50173.3.16.0/20173.3.16.1 to 173.3.31.254173.3.31.2554,094
51173.3.32.0/20173.3.32.1 to 173.3.47.254173.3.47.2554,094
52173.3.48.0/20173.3.48.1 to 173.3.63.254173.3.63.2554,094
53173.3.64.0/20173.3.64.1 to 173.3.79.254173.3.79.2554,094
54173.3.80.0/20173.3.80.1 to 173.3.95.254173.3.95.2554,094
55173.3.96.0/20173.3.96.1 to 173.3.111.254173.3.111.2554,094
56173.3.112.0/20173.3.112.1 to 173.3.127.254173.3.127.2554,094
57173.3.128.0/20173.3.128.1 to 173.3.143.254173.3.143.2554,094
58173.3.144.0/20173.3.144.1 to 173.3.159.254173.3.159.2554,094
59173.3.160.0/20173.3.160.1 to 173.3.175.254173.3.175.2554,094
60173.3.176.0/20173.3.176.1 to 173.3.191.254173.3.191.2554,094
61173.3.192.0/20173.3.192.1 to 173.3.207.254173.3.207.2554,094
62173.3.208.0/20173.3.208.1 to 173.3.223.254173.3.223.2554,094
63173.3.224.0/20173.3.224.1 to 173.3.239.254173.3.239.2554,094
64173.3.240.0/20173.3.240.1 to 173.3.255.254173.3.255.2554,094
65173.4.0.0/20173.4.0.1 to 173.4.15.254173.4.15.2554,094
66173.4.16.0/20173.4.16.1 to 173.4.31.254173.4.31.2554,094
67173.4.32.0/20173.4.32.1 to 173.4.47.254173.4.47.2554,094
68173.4.48.0/20173.4.48.1 to 173.4.63.254173.4.63.2554,094
69173.4.64.0/20173.4.64.1 to 173.4.79.254173.4.79.2554,094
70173.4.80.0/20173.4.80.1 to 173.4.95.254173.4.95.2554,094
71173.4.96.0/20173.4.96.1 to 173.4.111.254173.4.111.2554,094
72173.4.112.0/20173.4.112.1 to 173.4.127.254173.4.127.2554,094
73173.4.128.0/20173.4.128.1 to 173.4.143.254173.4.143.2554,094
74173.4.144.0/20173.4.144.1 to 173.4.159.254173.4.159.2554,094
75173.4.160.0/20173.4.160.1 to 173.4.175.254173.4.175.2554,094
76173.4.176.0/20173.4.176.1 to 173.4.191.254173.4.191.2554,094
77173.4.192.0/20173.4.192.1 to 173.4.207.254173.4.207.2554,094
78173.4.208.0/20173.4.208.1 to 173.4.223.254173.4.223.2554,094
79173.4.224.0/20173.4.224.1 to 173.4.239.254173.4.239.2554,094
80173.4.240.0/20173.4.240.1 to 173.4.255.254173.4.255.2554,094
81173.5.0.0/20173.5.0.1 to 173.5.15.254173.5.15.2554,094
82173.5.16.0/20173.5.16.1 to 173.5.31.254173.5.31.2554,094
83173.5.32.0/20173.5.32.1 to 173.5.47.254173.5.47.2554,094
84173.5.48.0/20173.5.48.1 to 173.5.63.254173.5.63.2554,094
85173.5.64.0/20173.5.64.1 to 173.5.79.254173.5.79.2554,094
86173.5.80.0/20173.5.80.1 to 173.5.95.254173.5.95.2554,094
87173.5.96.0/20173.5.96.1 to 173.5.111.254173.5.111.2554,094
88173.5.112.0/20173.5.112.1 to 173.5.127.254173.5.127.2554,094
89173.5.128.0/20173.5.128.1 to 173.5.143.254173.5.143.2554,094
90173.5.144.0/20173.5.144.1 to 173.5.159.254173.5.159.2554,094
91173.5.160.0/20173.5.160.1 to 173.5.175.254173.5.175.2554,094
92173.5.176.0/20173.5.176.1 to 173.5.191.254173.5.191.2554,094
93173.5.192.0/20173.5.192.1 to 173.5.207.254173.5.207.2554,094
94173.5.208.0/20173.5.208.1 to 173.5.223.254173.5.223.2554,094
95173.5.224.0/20173.5.224.1 to 173.5.239.254173.5.239.2554,094
96173.5.240.0/20173.5.240.1 to 173.5.255.254173.5.255.2554,094
97173.6.0.0/20173.6.0.1 to 173.6.15.254173.6.15.2554,094
98173.6.16.0/20173.6.16.1 to 173.6.31.254173.6.31.2554,094
99173.6.32.0/20173.6.32.1 to 173.6.47.254173.6.47.2554,094
100173.6.48.0/20173.6.48.1 to 173.6.63.254173.6.63.2554,094
101173.6.64.0/20173.6.64.1 to 173.6.79.254173.6.79.2554,094
102173.6.80.0/20173.6.80.1 to 173.6.95.254173.6.95.2554,094
103173.6.96.0/20173.6.96.1 to 173.6.111.254173.6.111.2554,094
104173.6.112.0/20173.6.112.1 to 173.6.127.254173.6.127.2554,094
105173.6.128.0/20173.6.128.1 to 173.6.143.254173.6.143.2554,094
106173.6.144.0/20173.6.144.1 to 173.6.159.254173.6.159.2554,094
107173.6.160.0/20173.6.160.1 to 173.6.175.254173.6.175.2554,094
108173.6.176.0/20173.6.176.1 to 173.6.191.254173.6.191.2554,094
109173.6.192.0/20173.6.192.1 to 173.6.207.254173.6.207.2554,094
110173.6.208.0/20173.6.208.1 to 173.6.223.254173.6.223.2554,094
111173.6.224.0/20173.6.224.1 to 173.6.239.254173.6.239.2554,094
112173.6.240.0/20173.6.240.1 to 173.6.255.254173.6.255.2554,094
113173.7.0.0/20173.7.0.1 to 173.7.15.254173.7.15.2554,094
114173.7.16.0/20173.7.16.1 to 173.7.31.254173.7.31.2554,094
115173.7.32.0/20173.7.32.1 to 173.7.47.254173.7.47.2554,094
116173.7.48.0/20173.7.48.1 to 173.7.63.254173.7.63.2554,094
117173.7.64.0/20173.7.64.1 to 173.7.79.254173.7.79.2554,094
118173.7.80.0/20173.7.80.1 to 173.7.95.254173.7.95.2554,094
119173.7.96.0/20173.7.96.1 to 173.7.111.254173.7.111.2554,094
120173.7.112.0/20173.7.112.1 to 173.7.127.254173.7.127.2554,094
121173.7.128.0/20173.7.128.1 to 173.7.143.254173.7.143.2554,094
122173.7.144.0/20173.7.144.1 to 173.7.159.254173.7.159.2554,094
123173.7.160.0/20173.7.160.1 to 173.7.175.254173.7.175.2554,094
124173.7.176.0/20173.7.176.1 to 173.7.191.254173.7.191.2554,094
125173.7.192.0/20173.7.192.1 to 173.7.207.254173.7.207.2554,094
126173.7.208.0/20173.7.208.1 to 173.7.223.254173.7.223.2554,094
127173.7.224.0/20173.7.224.1 to 173.7.239.254173.7.239.2554,094
128173.7.240.0/20173.7.240.1 to 173.7.255.254173.7.255.2554,094
129173.8.0.0/20173.8.0.1 to 173.8.15.254173.8.15.2554,094
130173.8.16.0/20173.8.16.1 to 173.8.31.254173.8.31.2554,094
131173.8.32.0/20173.8.32.1 to 173.8.47.254173.8.47.2554,094
132173.8.48.0/20173.8.48.1 to 173.8.63.254173.8.63.2554,094
133173.8.64.0/20173.8.64.1 to 173.8.79.254173.8.79.2554,094
134173.8.80.0/20173.8.80.1 to 173.8.95.254173.8.95.2554,094
135173.8.96.0/20173.8.96.1 to 173.8.111.254173.8.111.2554,094
136173.8.112.0/20173.8.112.1 to 173.8.127.254173.8.127.2554,094
137173.8.128.0/20173.8.128.1 to 173.8.143.254173.8.143.2554,094
138173.8.144.0/20173.8.144.1 to 173.8.159.254173.8.159.2554,094
139173.8.160.0/20173.8.160.1 to 173.8.175.254173.8.175.2554,094
140173.8.176.0/20173.8.176.1 to 173.8.191.254173.8.191.2554,094
141173.8.192.0/20173.8.192.1 to 173.8.207.254173.8.207.2554,094
142173.8.208.0/20173.8.208.1 to 173.8.223.254173.8.223.2554,094
143173.8.224.0/20173.8.224.1 to 173.8.239.254173.8.239.2554,094
144173.8.240.0/20173.8.240.1 to 173.8.255.254173.8.255.2554,094
145173.9.0.0/20173.9.0.1 to 173.9.15.254173.9.15.2554,094
146173.9.16.0/20173.9.16.1 to 173.9.31.254173.9.31.2554,094
147173.9.32.0/20173.9.32.1 to 173.9.47.254173.9.47.2554,094
148173.9.48.0/20173.9.48.1 to 173.9.63.254173.9.63.2554,094
149173.9.64.0/20173.9.64.1 to 173.9.79.254173.9.79.2554,094
150173.9.80.0/20173.9.80.1 to 173.9.95.254173.9.95.2554,094
151173.9.96.0/20173.9.96.1 to 173.9.111.254173.9.111.2554,094
152173.9.112.0/20173.9.112.1 to 173.9.127.254173.9.127.2554,094
153173.9.128.0/20173.9.128.1 to 173.9.143.254173.9.143.2554,094
154173.9.144.0/20173.9.144.1 to 173.9.159.254173.9.159.2554,094
155173.9.160.0/20173.9.160.1 to 173.9.175.254173.9.175.2554,094
156173.9.176.0/20173.9.176.1 to 173.9.191.254173.9.191.2554,094
157173.9.192.0/20173.9.192.1 to 173.9.207.254173.9.207.2554,094
158173.9.208.0/20173.9.208.1 to 173.9.223.254173.9.223.2554,094
159173.9.224.0/20173.9.224.1 to 173.9.239.254173.9.239.2554,094
160173.9.240.0/20173.9.240.1 to 173.9.255.254173.9.255.2554,094
161173.10.0.0/20173.10.0.1 to 173.10.15.254173.10.15.2554,094
162173.10.16.0/20173.10.16.1 to 173.10.31.254173.10.31.2554,094
163173.10.32.0/20173.10.32.1 to 173.10.47.254173.10.47.2554,094
164173.10.48.0/20173.10.48.1 to 173.10.63.254173.10.63.2554,094
165173.10.64.0/20173.10.64.1 to 173.10.79.254173.10.79.2554,094
166173.10.80.0/20173.10.80.1 to 173.10.95.254173.10.95.2554,094
167173.10.96.0/20173.10.96.1 to 173.10.111.254173.10.111.2554,094
168173.10.112.0/20173.10.112.1 to 173.10.127.254173.10.127.2554,094
169173.10.128.0/20173.10.128.1 to 173.10.143.254173.10.143.2554,094
170173.10.144.0/20173.10.144.1 to 173.10.159.254173.10.159.2554,094
171173.10.160.0/20173.10.160.1 to 173.10.175.254173.10.175.2554,094
172173.10.176.0/20173.10.176.1 to 173.10.191.254173.10.191.2554,094
173173.10.192.0/20173.10.192.1 to 173.10.207.254173.10.207.2554,094
174173.10.208.0/20173.10.208.1 to 173.10.223.254173.10.223.2554,094
175173.10.224.0/20173.10.224.1 to 173.10.239.254173.10.239.2554,094
176173.10.240.0/20173.10.240.1 to 173.10.255.254173.10.255.2554,094
177173.11.0.0/20173.11.0.1 to 173.11.15.254173.11.15.2554,094
178173.11.16.0/20173.11.16.1 to 173.11.31.254173.11.31.2554,094
179173.11.32.0/20173.11.32.1 to 173.11.47.254173.11.47.2554,094
180173.11.48.0/20173.11.48.1 to 173.11.63.254173.11.63.2554,094
181173.11.64.0/20173.11.64.1 to 173.11.79.254173.11.79.2554,094
182173.11.80.0/20173.11.80.1 to 173.11.95.254173.11.95.2554,094
183173.11.96.0/20173.11.96.1 to 173.11.111.254173.11.111.2554,094
184173.11.112.0/20173.11.112.1 to 173.11.127.254173.11.127.2554,094
185173.11.128.0/20173.11.128.1 to 173.11.143.254173.11.143.2554,094
186173.11.144.0/20173.11.144.1 to 173.11.159.254173.11.159.2554,094
187173.11.160.0/20173.11.160.1 to 173.11.175.254173.11.175.2554,094
188173.11.176.0/20173.11.176.1 to 173.11.191.254173.11.191.2554,094
189173.11.192.0/20173.11.192.1 to 173.11.207.254173.11.207.2554,094
190173.11.208.0/20173.11.208.1 to 173.11.223.254173.11.223.2554,094
191173.11.224.0/20173.11.224.1 to 173.11.239.254173.11.239.2554,094
192173.11.240.0/20173.11.240.1 to 173.11.255.254173.11.255.2554,094
193173.12.0.0/20173.12.0.1 to 173.12.15.254173.12.15.2554,094
194173.12.16.0/20173.12.16.1 to 173.12.31.254173.12.31.2554,094
195173.12.32.0/20173.12.32.1 to 173.12.47.254173.12.47.2554,094
196173.12.48.0/20173.12.48.1 to 173.12.63.254173.12.63.2554,094
197173.12.64.0/20173.12.64.1 to 173.12.79.254173.12.79.2554,094
198173.12.80.0/20173.12.80.1 to 173.12.95.254173.12.95.2554,094
199173.12.96.0/20173.12.96.1 to 173.12.111.254173.12.111.2554,094
200173.12.112.0/20173.12.112.1 to 173.12.127.254173.12.127.2554,094
201173.12.128.0/20173.12.128.1 to 173.12.143.254173.12.143.2554,094
202173.12.144.0/20173.12.144.1 to 173.12.159.254173.12.159.2554,094
203173.12.160.0/20173.12.160.1 to 173.12.175.254173.12.175.2554,094
204173.12.176.0/20173.12.176.1 to 173.12.191.254173.12.191.2554,094
205173.12.192.0/20173.12.192.1 to 173.12.207.254173.12.207.2554,094
206173.12.208.0/20173.12.208.1 to 173.12.223.254173.12.223.2554,094
207173.12.224.0/20173.12.224.1 to 173.12.239.254173.12.239.2554,094
208173.12.240.0/20173.12.240.1 to 173.12.255.254173.12.255.2554,094
209173.13.0.0/20173.13.0.1 to 173.13.15.254173.13.15.2554,094
210173.13.16.0/20173.13.16.1 to 173.13.31.254173.13.31.2554,094
211173.13.32.0/20173.13.32.1 to 173.13.47.254173.13.47.2554,094
212173.13.48.0/20173.13.48.1 to 173.13.63.254173.13.63.2554,094
213173.13.64.0/20173.13.64.1 to 173.13.79.254173.13.79.2554,094
214173.13.80.0/20173.13.80.1 to 173.13.95.254173.13.95.2554,094
215173.13.96.0/20173.13.96.1 to 173.13.111.254173.13.111.2554,094
216173.13.112.0/20173.13.112.1 to 173.13.127.254173.13.127.2554,094
217173.13.128.0/20173.13.128.1 to 173.13.143.254173.13.143.2554,094
218173.13.144.0/20173.13.144.1 to 173.13.159.254173.13.159.2554,094
219173.13.160.0/20173.13.160.1 to 173.13.175.254173.13.175.2554,094
220173.13.176.0/20173.13.176.1 to 173.13.191.254173.13.191.2554,094
221173.13.192.0/20173.13.192.1 to 173.13.207.254173.13.207.2554,094
222173.13.208.0/20173.13.208.1 to 173.13.223.254173.13.223.2554,094
223173.13.224.0/20173.13.224.1 to 173.13.239.254173.13.239.2554,094
224173.13.240.0/20173.13.240.1 to 173.13.255.254173.13.255.2554,094
225173.14.0.0/20173.14.0.1 to 173.14.15.254173.14.15.2554,094
226173.14.16.0/20173.14.16.1 to 173.14.31.254173.14.31.2554,094
227173.14.32.0/20173.14.32.1 to 173.14.47.254173.14.47.2554,094
228173.14.48.0/20173.14.48.1 to 173.14.63.254173.14.63.2554,094
229173.14.64.0/20173.14.64.1 to 173.14.79.254173.14.79.2554,094
230173.14.80.0/20173.14.80.1 to 173.14.95.254173.14.95.2554,094
231173.14.96.0/20173.14.96.1 to 173.14.111.254173.14.111.2554,094
232173.14.112.0/20173.14.112.1 to 173.14.127.254173.14.127.2554,094
233173.14.128.0/20173.14.128.1 to 173.14.143.254173.14.143.2554,094
234173.14.144.0/20173.14.144.1 to 173.14.159.254173.14.159.2554,094
235173.14.160.0/20173.14.160.1 to 173.14.175.254173.14.175.2554,094
236173.14.176.0/20173.14.176.1 to 173.14.191.254173.14.191.2554,094
237173.14.192.0/20173.14.192.1 to 173.14.207.254173.14.207.2554,094
238173.14.208.0/20173.14.208.1 to 173.14.223.254173.14.223.2554,094
239173.14.224.0/20173.14.224.1 to 173.14.239.254173.14.239.2554,094
240173.14.240.0/20173.14.240.1 to 173.14.255.254173.14.255.2554,094
241173.15.0.0/20173.15.0.1 to 173.15.15.254173.15.15.2554,094
242173.15.16.0/20173.15.16.1 to 173.15.31.254173.15.31.2554,094
243173.15.32.0/20173.15.32.1 to 173.15.47.254173.15.47.2554,094
244173.15.48.0/20173.15.48.1 to 173.15.63.254173.15.63.2554,094
245173.15.64.0/20173.15.64.1 to 173.15.79.254173.15.79.2554,094
246173.15.80.0/20173.15.80.1 to 173.15.95.254173.15.95.2554,094
247173.15.96.0/20173.15.96.1 to 173.15.111.254173.15.111.2554,094
248173.15.112.0/20173.15.112.1 to 173.15.127.254173.15.127.2554,094
249173.15.128.0/20173.15.128.1 to 173.15.143.254173.15.143.2554,094
250173.15.144.0/20173.15.144.1 to 173.15.159.254173.15.159.2554,094
251173.15.160.0/20173.15.160.1 to 173.15.175.254173.15.175.2554,094
252173.15.176.0/20173.15.176.1 to 173.15.191.254173.15.191.2554,094
253173.15.192.0/20173.15.192.1 to 173.15.207.254173.15.207.2554,094
254173.15.208.0/20173.15.208.1 to 173.15.223.254173.15.223.2554,094
255173.15.224.0/20173.15.224.1 to 173.15.239.254173.15.239.2554,094
256173.15.240.0/20173.15.240.1 to 173.15.255.254173.15.255.2554,094

IPv4 CIDR reference (/0 to /32)

IPv4 prefix lengths
PrefixSubnet maskWildcardAddressesUsable hostsSizeTypical use
/00.0.0.0255.255.255.2554,294,967,2964,294,967,29416,777,216 × /24
/1128.0.0.0127.255.255.2552,147,483,6482,147,483,6468,388,608 × /24
/2192.0.0.063.255.255.2551,073,741,8241,073,741,8224,194,304 × /24
/3224.0.0.031.255.255.255536,870,912536,870,9102,097,152 × /24
/4240.0.0.015.255.255.255268,435,456268,435,4541,048,576 × /24
/5248.0.0.07.255.255.255134,217,728134,217,726524,288 × /24
/6252.0.0.03.255.255.25567,108,86467,108,862262,144 × /24
/7254.0.0.01.255.255.25533,554,43233,554,430131,072 × /24
/8255.0.0.00.255.255.25516,777,21616,777,21465,536 × /24Old class A; 10.0.0.0/8
/9255.128.0.00.127.255.2558,388,6088,388,60632,768 × /24
/10255.192.0.00.63.255.2554,194,3044,194,30216,384 × /24
/11255.224.0.00.31.255.2552,097,1522,097,1508,192 × /24
/12255.240.0.00.15.255.2551,048,5761,048,5744,096 × /24172.16.0.0/12
/13255.248.0.00.7.255.255524,288524,2862,048 × /24
/14255.252.0.00.3.255.255262,144262,1421,024 × /24
/15255.254.0.00.1.255.255131,072131,070512 × /24
/16255.255.0.00.0.255.25565,53665,534256 × /24Old class B; 192.168.0.0/16
/17255.255.128.00.0.127.25532,76832,766128 × /24
/18255.255.192.00.0.63.25516,38416,38264 × /24
/19255.255.224.00.0.31.2558,1928,19032 × /24
/20255.255.240.00.0.15.2554,0964,09416 × /24
/21255.255.248.00.0.7.2552,0482,0468 × /24
/22255.255.252.00.0.3.2551,0241,0224 × /24Large office or guest Wi-Fi (1,022 hosts)
/23255.255.254.00.0.1.2555125102 × /24Larger office LAN (510 hosts)
/24255.255.255.00.0.0.2552562541 × /24Typical office LAN (old class C)
/25255.255.255.1280.0.0.1271281261/2 of a /24Smaller LAN or VLAN
/26255.255.255.1920.0.0.6364621/4 of a /24Smaller LAN or VLAN
/27255.255.255.2240.0.0.3132301/8 of a /24Small VLAN, phones, cameras
/28255.255.255.2400.0.0.1516141/16 of a /24Small VLAN, phones, cameras
/29255.255.255.2480.0.0.7861/32 of a /24Small fixed public block (5 usable)
/30255.255.255.2520.0.0.3421/64 of a /24Point-to-point (old style)
/31255.255.255.2540.0.0.1221/128 of a /24Point-to-point link (RFC 3021)
/32255.255.255.2550.0.0.0111/256 of a /24One host

IPv6 prefix reference

IPv6 prefix lengths
PrefixAddresses/64 LANs/48 sitesNibbleTypical use
/342,535,295,865,117,307,932,921,825,928,971,026,432 (2^125)2,305,843,009,213,693,95235,184,372,088,832NoAll global unicast (2000::/3)
/165,192,296,858,534,827,628,530,496,329,220,096 (2^112)281,474,976,710,6564,294,967,296Yes
/20324,518,553,658,426,726,783,156,020,576,256 (2^108)17,592,186,044,416268,435,456YesLarge provider allocation (RIPE minimum for some)
/29633,825,300,114,114,700,748,351,602,688 (2^99)34,359,738,368524,288NoRIPE allocation to a provider (often)
/3279,228,162,514,264,337,593,543,950,336 (2^96)4,294,967,29665,536YesProvider allocation (RIPE default)
/364,951,760,157,141,521,099,596,496,896 (2^92)268,435,4564,096Yes
/40309,485,009,821,345,068,724,781,056 (2^88)16,777,216256Yes
/4419,342,813,113,834,066,795,298,816 (2^84)1,048,57616Yes
/481,208,925,819,614,629,174,706,176 (2^80)65,5361YesOne site or organisation (RIPE PI / assignment)
/5275,557,863,725,914,323,419,136 (2^76)4,096Yes
/564,722,366,482,869,645,213,696 (2^72)256YesSmall site or home (common provider assignment)
/60295,147,905,179,352,825,856 (2^68)16YesSome home broadband (16 LANs)
/6418,446,744,073,709,551,616 (2^64)1YesOne LAN or VLAN (needed for SLAAC)
/7272,057,594,037,927,936 (2^56)1/256 of a /64Yes
/80281,474,976,710,656 (2^48)1/65,536 of a /64Yes
/964,294,967,2961/4,294,967,296 of a /64YesEmbeds an IPv4 address (NAT64)
/11265,5361/281,474,976,710,656 of a /64Yes
/1202561/72,057,594,037,927,936 of a /64Yes
/124161/1,152,921,504,606,846,976 of a /64Yes
/12641/4,611,686,018,427,387,904 of a /64No
/12721/9,223,372,036,854,775,808 of a /64NoPoint-to-point link (RFC 6164)
/12811/18,446,744,073,709,551,616 of a /64YesOne host or loopback

Private and special ranges

IPv4

Special-purpose ranges
RangeNameWhat it is
255.255.255.255/32Limited broadcastEvery host on the local network
0.0.0.0/8This networkNot routed; 0.0.0.0 means "any address" in settings
10.0.0.0/8Private (RFC 1918)Office and home networks; not routed on the internet
100.64.0.0/10Shared address space (CGNAT)Used by providers behind carrier-grade NAT (RFC 6598)
127.0.0.0/8LoopbackThis computer
169.254.0.0/16Link-local (APIPA)Self-assigned when no DHCP server answers
172.16.0.0/12Private (RFC 1918)Office and home networks; not routed on the internet
192.0.0.0/24IETF protocol assignmentsSpecial uses such as DS-Lite
192.0.2.0/24Documentation (TEST-NET-1)For examples; never used on a network
192.88.99.0/246to4 relay (deprecated)Formerly anycast for 6to4
192.168.0.0/16Private (RFC 1918)Office and home networks; not routed on the internet
198.18.0.0/15BenchmarkingNetwork equipment testing (RFC 2544)
198.51.100.0/24Documentation (TEST-NET-2)For examples; never used on a network
203.0.113.0/24Documentation (TEST-NET-3)For examples; never used on a network
224.0.0.0/4MulticastOne-to-many traffic, such as IPTV and routing protocols
240.0.0.0/4ReservedFuture use; not usable on most systems

IPv6

Special-purpose ranges
RangeNameWhat it is
::/128UnspecifiedNo address; :: means "any address" in settings
::1/128LoopbackThis computer
::ffff:0:0/96IPv4-mappedAn IPv4 address written as IPv6
64:ff9b::/96NAT64IPv4 addresses reached through a NAT64 gateway
100::/64Discard onlyTraffic sent here is dropped (RFC 6666)
2001:db8::/32DocumentationFor examples; never used on a network
2001::/32TeredoIPv6 tunnelled over IPv4 UDP
2002::/166to4IPv6 tunnelled over IPv4 (largely retired)
3fff::/20DocumentationFor examples (RFC 9637)
fc00::/7Unique local (ULA)Private IPv6, like RFC 1918; usually fd00::/8
fe80::/10Link-localEvery IPv6 interface has one; not routed
ff00::/8MulticastOne-to-many traffic; replaces broadcast
2000::/3Global unicastPublic internet addresses

About this tool

A network is written as an address and a prefix length, such as 192.168.1.0/24: the first 24 bits name the network and the rest number the devices on it. The calculator works out where the network starts and ends, how many devices it holds, its subnet and wildcard masks, and the reverse DNS zone to ask your provider for.

It also splits a network into equal smaller ones (one per VLAN or site), turns a range of addresses into the fewest CIDR blocks for a firewall rule, and lists every IPv4 prefix length and the common IPv6 ones in reference tables.

Common questions

Why are two addresses lost in every IPv4 subnet?

The first address names the network and the last is the broadcast address, so a /24 has 256 addresses but 254 for devices. A /31 (a link between two routers) and a /32 (one host) are the exceptions.

What size of IPv6 network should a LAN use?

Always /64. Devices pick their own address within it (SLAAC), which needs the full 64 bits. A site usually gets a /48 or /56 from its provider, which holds 65,536 or 256 LANs.

What is a wildcard mask?

The subnet mask turned inside out: 255.255.255.0 becomes 0.0.0.255. Cisco access lists and OSPF use it to say which bits must match.

Which ranges can I use inside an office?

IPv4: 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16. IPv6: unique local addresses from fd00::/8, though most networks use the public prefix from their provider.