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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.

Network210.128.0.0/9
Usable hosts8,388,606
Subnet mask255.128.0.0
Addresses8,388,608
Network address
210.128.0.0
Broadcast address
210.255.255.255
First usable
210.128.0.1
Last usable
210.255.255.254
Usable hosts
8,388,606 (8,388,608 less the network and broadcast addresses)
Subnet mask
255.128.0.0
Wildcard mask
0.127.255.255 (Cisco ACLs, OSPF)
Prefix length
/9
Type
Public public
Old class
C (default /24)
As numbers
Hex D2800000 · Integer 3531603968 to 3539992575
Reverse DNS zones
128.210.in-addr.arpa
129.210.in-addr.arpa
130.210.in-addr.arpa
131.210.in-addr.arpa
132.210.in-addr.arpa
133.210.in-addr.arpa
134.210.in-addr.arpa
135.210.in-addr.arpa
136.210.in-addr.arpa
137.210.in-addr.arpa
138.210.in-addr.arpa
139.210.in-addr.arpa
140.210.in-addr.arpa
141.210.in-addr.arpa
142.210.in-addr.arpa
143.210.in-addr.arpa
and 112 more
/9 is not on a 8-bit boundary, so it takes 128 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11010010.10000000.00000000.00000000210.128.0.0
Subnet mask11111111.10000000.00000000.00000000255.128.0.0
Network11010010.10000000.00000000.00000000210.128.0.0
Broadcast11010010.11111111.11111111.11111111210.255.255.255
Split into smaller subnets/18
/10 (2)/11 (4)/12 (8)/13 (16)/14 (32)/15 (64)/16 (128)/17 (256)/18 (512)/19 (1,024)/20 (2,048)/21 (4,096)

210.128.0.0/9 makes 512 subnets of /18; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1210.128.0.0/18210.128.0.1 to 210.128.63.254210.128.63.25516,382
2210.128.64.0/18210.128.64.1 to 210.128.127.254210.128.127.25516,382
3210.128.128.0/18210.128.128.1 to 210.128.191.254210.128.191.25516,382
4210.128.192.0/18210.128.192.1 to 210.128.255.254210.128.255.25516,382
5210.129.0.0/18210.129.0.1 to 210.129.63.254210.129.63.25516,382
6210.129.64.0/18210.129.64.1 to 210.129.127.254210.129.127.25516,382
7210.129.128.0/18210.129.128.1 to 210.129.191.254210.129.191.25516,382
8210.129.192.0/18210.129.192.1 to 210.129.255.254210.129.255.25516,382
9210.130.0.0/18210.130.0.1 to 210.130.63.254210.130.63.25516,382
10210.130.64.0/18210.130.64.1 to 210.130.127.254210.130.127.25516,382
11210.130.128.0/18210.130.128.1 to 210.130.191.254210.130.191.25516,382
12210.130.192.0/18210.130.192.1 to 210.130.255.254210.130.255.25516,382
13210.131.0.0/18210.131.0.1 to 210.131.63.254210.131.63.25516,382
14210.131.64.0/18210.131.64.1 to 210.131.127.254210.131.127.25516,382
15210.131.128.0/18210.131.128.1 to 210.131.191.254210.131.191.25516,382
16210.131.192.0/18210.131.192.1 to 210.131.255.254210.131.255.25516,382
17210.132.0.0/18210.132.0.1 to 210.132.63.254210.132.63.25516,382
18210.132.64.0/18210.132.64.1 to 210.132.127.254210.132.127.25516,382
19210.132.128.0/18210.132.128.1 to 210.132.191.254210.132.191.25516,382
20210.132.192.0/18210.132.192.1 to 210.132.255.254210.132.255.25516,382
21210.133.0.0/18210.133.0.1 to 210.133.63.254210.133.63.25516,382
22210.133.64.0/18210.133.64.1 to 210.133.127.254210.133.127.25516,382
23210.133.128.0/18210.133.128.1 to 210.133.191.254210.133.191.25516,382
24210.133.192.0/18210.133.192.1 to 210.133.255.254210.133.255.25516,382
25210.134.0.0/18210.134.0.1 to 210.134.63.254210.134.63.25516,382
26210.134.64.0/18210.134.64.1 to 210.134.127.254210.134.127.25516,382
27210.134.128.0/18210.134.128.1 to 210.134.191.254210.134.191.25516,382
28210.134.192.0/18210.134.192.1 to 210.134.255.254210.134.255.25516,382
29210.135.0.0/18210.135.0.1 to 210.135.63.254210.135.63.25516,382
30210.135.64.0/18210.135.64.1 to 210.135.127.254210.135.127.25516,382
31210.135.128.0/18210.135.128.1 to 210.135.191.254210.135.191.25516,382
32210.135.192.0/18210.135.192.1 to 210.135.255.254210.135.255.25516,382
33210.136.0.0/18210.136.0.1 to 210.136.63.254210.136.63.25516,382
34210.136.64.0/18210.136.64.1 to 210.136.127.254210.136.127.25516,382
35210.136.128.0/18210.136.128.1 to 210.136.191.254210.136.191.25516,382
36210.136.192.0/18210.136.192.1 to 210.136.255.254210.136.255.25516,382
37210.137.0.0/18210.137.0.1 to 210.137.63.254210.137.63.25516,382
38210.137.64.0/18210.137.64.1 to 210.137.127.254210.137.127.25516,382
39210.137.128.0/18210.137.128.1 to 210.137.191.254210.137.191.25516,382
40210.137.192.0/18210.137.192.1 to 210.137.255.254210.137.255.25516,382
41210.138.0.0/18210.138.0.1 to 210.138.63.254210.138.63.25516,382
42210.138.64.0/18210.138.64.1 to 210.138.127.254210.138.127.25516,382
43210.138.128.0/18210.138.128.1 to 210.138.191.254210.138.191.25516,382
44210.138.192.0/18210.138.192.1 to 210.138.255.254210.138.255.25516,382
45210.139.0.0/18210.139.0.1 to 210.139.63.254210.139.63.25516,382
46210.139.64.0/18210.139.64.1 to 210.139.127.254210.139.127.25516,382
47210.139.128.0/18210.139.128.1 to 210.139.191.254210.139.191.25516,382
48210.139.192.0/18210.139.192.1 to 210.139.255.254210.139.255.25516,382
49210.140.0.0/18210.140.0.1 to 210.140.63.254210.140.63.25516,382
50210.140.64.0/18210.140.64.1 to 210.140.127.254210.140.127.25516,382
51210.140.128.0/18210.140.128.1 to 210.140.191.254210.140.191.25516,382
52210.140.192.0/18210.140.192.1 to 210.140.255.254210.140.255.25516,382
53210.141.0.0/18210.141.0.1 to 210.141.63.254210.141.63.25516,382
54210.141.64.0/18210.141.64.1 to 210.141.127.254210.141.127.25516,382
55210.141.128.0/18210.141.128.1 to 210.141.191.254210.141.191.25516,382
56210.141.192.0/18210.141.192.1 to 210.141.255.254210.141.255.25516,382
57210.142.0.0/18210.142.0.1 to 210.142.63.254210.142.63.25516,382
58210.142.64.0/18210.142.64.1 to 210.142.127.254210.142.127.25516,382
59210.142.128.0/18210.142.128.1 to 210.142.191.254210.142.191.25516,382
60210.142.192.0/18210.142.192.1 to 210.142.255.254210.142.255.25516,382
61210.143.0.0/18210.143.0.1 to 210.143.63.254210.143.63.25516,382
62210.143.64.0/18210.143.64.1 to 210.143.127.254210.143.127.25516,382
63210.143.128.0/18210.143.128.1 to 210.143.191.254210.143.191.25516,382
64210.143.192.0/18210.143.192.1 to 210.143.255.254210.143.255.25516,382
65210.144.0.0/18210.144.0.1 to 210.144.63.254210.144.63.25516,382
66210.144.64.0/18210.144.64.1 to 210.144.127.254210.144.127.25516,382
67210.144.128.0/18210.144.128.1 to 210.144.191.254210.144.191.25516,382
68210.144.192.0/18210.144.192.1 to 210.144.255.254210.144.255.25516,382
69210.145.0.0/18210.145.0.1 to 210.145.63.254210.145.63.25516,382
70210.145.64.0/18210.145.64.1 to 210.145.127.254210.145.127.25516,382
71210.145.128.0/18210.145.128.1 to 210.145.191.254210.145.191.25516,382
72210.145.192.0/18210.145.192.1 to 210.145.255.254210.145.255.25516,382
73210.146.0.0/18210.146.0.1 to 210.146.63.254210.146.63.25516,382
74210.146.64.0/18210.146.64.1 to 210.146.127.254210.146.127.25516,382
75210.146.128.0/18210.146.128.1 to 210.146.191.254210.146.191.25516,382
76210.146.192.0/18210.146.192.1 to 210.146.255.254210.146.255.25516,382
77210.147.0.0/18210.147.0.1 to 210.147.63.254210.147.63.25516,382
78210.147.64.0/18210.147.64.1 to 210.147.127.254210.147.127.25516,382
79210.147.128.0/18210.147.128.1 to 210.147.191.254210.147.191.25516,382
80210.147.192.0/18210.147.192.1 to 210.147.255.254210.147.255.25516,382
81210.148.0.0/18210.148.0.1 to 210.148.63.254210.148.63.25516,382
82210.148.64.0/18210.148.64.1 to 210.148.127.254210.148.127.25516,382
83210.148.128.0/18210.148.128.1 to 210.148.191.254210.148.191.25516,382
84210.148.192.0/18210.148.192.1 to 210.148.255.254210.148.255.25516,382
85210.149.0.0/18210.149.0.1 to 210.149.63.254210.149.63.25516,382
86210.149.64.0/18210.149.64.1 to 210.149.127.254210.149.127.25516,382
87210.149.128.0/18210.149.128.1 to 210.149.191.254210.149.191.25516,382
88210.149.192.0/18210.149.192.1 to 210.149.255.254210.149.255.25516,382
89210.150.0.0/18210.150.0.1 to 210.150.63.254210.150.63.25516,382
90210.150.64.0/18210.150.64.1 to 210.150.127.254210.150.127.25516,382
91210.150.128.0/18210.150.128.1 to 210.150.191.254210.150.191.25516,382
92210.150.192.0/18210.150.192.1 to 210.150.255.254210.150.255.25516,382
93210.151.0.0/18210.151.0.1 to 210.151.63.254210.151.63.25516,382
94210.151.64.0/18210.151.64.1 to 210.151.127.254210.151.127.25516,382
95210.151.128.0/18210.151.128.1 to 210.151.191.254210.151.191.25516,382
96210.151.192.0/18210.151.192.1 to 210.151.255.254210.151.255.25516,382
97210.152.0.0/18210.152.0.1 to 210.152.63.254210.152.63.25516,382
98210.152.64.0/18210.152.64.1 to 210.152.127.254210.152.127.25516,382
99210.152.128.0/18210.152.128.1 to 210.152.191.254210.152.191.25516,382
100210.152.192.0/18210.152.192.1 to 210.152.255.254210.152.255.25516,382
101210.153.0.0/18210.153.0.1 to 210.153.63.254210.153.63.25516,382
102210.153.64.0/18210.153.64.1 to 210.153.127.254210.153.127.25516,382
103210.153.128.0/18210.153.128.1 to 210.153.191.254210.153.191.25516,382
104210.153.192.0/18210.153.192.1 to 210.153.255.254210.153.255.25516,382
105210.154.0.0/18210.154.0.1 to 210.154.63.254210.154.63.25516,382
106210.154.64.0/18210.154.64.1 to 210.154.127.254210.154.127.25516,382
107210.154.128.0/18210.154.128.1 to 210.154.191.254210.154.191.25516,382
108210.154.192.0/18210.154.192.1 to 210.154.255.254210.154.255.25516,382
109210.155.0.0/18210.155.0.1 to 210.155.63.254210.155.63.25516,382
110210.155.64.0/18210.155.64.1 to 210.155.127.254210.155.127.25516,382
111210.155.128.0/18210.155.128.1 to 210.155.191.254210.155.191.25516,382
112210.155.192.0/18210.155.192.1 to 210.155.255.254210.155.255.25516,382
113210.156.0.0/18210.156.0.1 to 210.156.63.254210.156.63.25516,382
114210.156.64.0/18210.156.64.1 to 210.156.127.254210.156.127.25516,382
115210.156.128.0/18210.156.128.1 to 210.156.191.254210.156.191.25516,382
116210.156.192.0/18210.156.192.1 to 210.156.255.254210.156.255.25516,382
117210.157.0.0/18210.157.0.1 to 210.157.63.254210.157.63.25516,382
118210.157.64.0/18210.157.64.1 to 210.157.127.254210.157.127.25516,382
119210.157.128.0/18210.157.128.1 to 210.157.191.254210.157.191.25516,382
120210.157.192.0/18210.157.192.1 to 210.157.255.254210.157.255.25516,382
121210.158.0.0/18210.158.0.1 to 210.158.63.254210.158.63.25516,382
122210.158.64.0/18210.158.64.1 to 210.158.127.254210.158.127.25516,382
123210.158.128.0/18210.158.128.1 to 210.158.191.254210.158.191.25516,382
124210.158.192.0/18210.158.192.1 to 210.158.255.254210.158.255.25516,382
125210.159.0.0/18210.159.0.1 to 210.159.63.254210.159.63.25516,382
126210.159.64.0/18210.159.64.1 to 210.159.127.254210.159.127.25516,382
127210.159.128.0/18210.159.128.1 to 210.159.191.254210.159.191.25516,382
128210.159.192.0/18210.159.192.1 to 210.159.255.254210.159.255.25516,382
129210.160.0.0/18210.160.0.1 to 210.160.63.254210.160.63.25516,382
130210.160.64.0/18210.160.64.1 to 210.160.127.254210.160.127.25516,382
131210.160.128.0/18210.160.128.1 to 210.160.191.254210.160.191.25516,382
132210.160.192.0/18210.160.192.1 to 210.160.255.254210.160.255.25516,382
133210.161.0.0/18210.161.0.1 to 210.161.63.254210.161.63.25516,382
134210.161.64.0/18210.161.64.1 to 210.161.127.254210.161.127.25516,382
135210.161.128.0/18210.161.128.1 to 210.161.191.254210.161.191.25516,382
136210.161.192.0/18210.161.192.1 to 210.161.255.254210.161.255.25516,382
137210.162.0.0/18210.162.0.1 to 210.162.63.254210.162.63.25516,382
138210.162.64.0/18210.162.64.1 to 210.162.127.254210.162.127.25516,382
139210.162.128.0/18210.162.128.1 to 210.162.191.254210.162.191.25516,382
140210.162.192.0/18210.162.192.1 to 210.162.255.254210.162.255.25516,382
141210.163.0.0/18210.163.0.1 to 210.163.63.254210.163.63.25516,382
142210.163.64.0/18210.163.64.1 to 210.163.127.254210.163.127.25516,382
143210.163.128.0/18210.163.128.1 to 210.163.191.254210.163.191.25516,382
144210.163.192.0/18210.163.192.1 to 210.163.255.254210.163.255.25516,382
145210.164.0.0/18210.164.0.1 to 210.164.63.254210.164.63.25516,382
146210.164.64.0/18210.164.64.1 to 210.164.127.254210.164.127.25516,382
147210.164.128.0/18210.164.128.1 to 210.164.191.254210.164.191.25516,382
148210.164.192.0/18210.164.192.1 to 210.164.255.254210.164.255.25516,382
149210.165.0.0/18210.165.0.1 to 210.165.63.254210.165.63.25516,382
150210.165.64.0/18210.165.64.1 to 210.165.127.254210.165.127.25516,382
151210.165.128.0/18210.165.128.1 to 210.165.191.254210.165.191.25516,382
152210.165.192.0/18210.165.192.1 to 210.165.255.254210.165.255.25516,382
153210.166.0.0/18210.166.0.1 to 210.166.63.254210.166.63.25516,382
154210.166.64.0/18210.166.64.1 to 210.166.127.254210.166.127.25516,382
155210.166.128.0/18210.166.128.1 to 210.166.191.254210.166.191.25516,382
156210.166.192.0/18210.166.192.1 to 210.166.255.254210.166.255.25516,382
157210.167.0.0/18210.167.0.1 to 210.167.63.254210.167.63.25516,382
158210.167.64.0/18210.167.64.1 to 210.167.127.254210.167.127.25516,382
159210.167.128.0/18210.167.128.1 to 210.167.191.254210.167.191.25516,382
160210.167.192.0/18210.167.192.1 to 210.167.255.254210.167.255.25516,382
161210.168.0.0/18210.168.0.1 to 210.168.63.254210.168.63.25516,382
162210.168.64.0/18210.168.64.1 to 210.168.127.254210.168.127.25516,382
163210.168.128.0/18210.168.128.1 to 210.168.191.254210.168.191.25516,382
164210.168.192.0/18210.168.192.1 to 210.168.255.254210.168.255.25516,382
165210.169.0.0/18210.169.0.1 to 210.169.63.254210.169.63.25516,382
166210.169.64.0/18210.169.64.1 to 210.169.127.254210.169.127.25516,382
167210.169.128.0/18210.169.128.1 to 210.169.191.254210.169.191.25516,382
168210.169.192.0/18210.169.192.1 to 210.169.255.254210.169.255.25516,382
169210.170.0.0/18210.170.0.1 to 210.170.63.254210.170.63.25516,382
170210.170.64.0/18210.170.64.1 to 210.170.127.254210.170.127.25516,382
171210.170.128.0/18210.170.128.1 to 210.170.191.254210.170.191.25516,382
172210.170.192.0/18210.170.192.1 to 210.170.255.254210.170.255.25516,382
173210.171.0.0/18210.171.0.1 to 210.171.63.254210.171.63.25516,382
174210.171.64.0/18210.171.64.1 to 210.171.127.254210.171.127.25516,382
175210.171.128.0/18210.171.128.1 to 210.171.191.254210.171.191.25516,382
176210.171.192.0/18210.171.192.1 to 210.171.255.254210.171.255.25516,382
177210.172.0.0/18210.172.0.1 to 210.172.63.254210.172.63.25516,382
178210.172.64.0/18210.172.64.1 to 210.172.127.254210.172.127.25516,382
179210.172.128.0/18210.172.128.1 to 210.172.191.254210.172.191.25516,382
180210.172.192.0/18210.172.192.1 to 210.172.255.254210.172.255.25516,382
181210.173.0.0/18210.173.0.1 to 210.173.63.254210.173.63.25516,382
182210.173.64.0/18210.173.64.1 to 210.173.127.254210.173.127.25516,382
183210.173.128.0/18210.173.128.1 to 210.173.191.254210.173.191.25516,382
184210.173.192.0/18210.173.192.1 to 210.173.255.254210.173.255.25516,382
185210.174.0.0/18210.174.0.1 to 210.174.63.254210.174.63.25516,382
186210.174.64.0/18210.174.64.1 to 210.174.127.254210.174.127.25516,382
187210.174.128.0/18210.174.128.1 to 210.174.191.254210.174.191.25516,382
188210.174.192.0/18210.174.192.1 to 210.174.255.254210.174.255.25516,382
189210.175.0.0/18210.175.0.1 to 210.175.63.254210.175.63.25516,382
190210.175.64.0/18210.175.64.1 to 210.175.127.254210.175.127.25516,382
191210.175.128.0/18210.175.128.1 to 210.175.191.254210.175.191.25516,382
192210.175.192.0/18210.175.192.1 to 210.175.255.254210.175.255.25516,382
193210.176.0.0/18210.176.0.1 to 210.176.63.254210.176.63.25516,382
194210.176.64.0/18210.176.64.1 to 210.176.127.254210.176.127.25516,382
195210.176.128.0/18210.176.128.1 to 210.176.191.254210.176.191.25516,382
196210.176.192.0/18210.176.192.1 to 210.176.255.254210.176.255.25516,382
197210.177.0.0/18210.177.0.1 to 210.177.63.254210.177.63.25516,382
198210.177.64.0/18210.177.64.1 to 210.177.127.254210.177.127.25516,382
199210.177.128.0/18210.177.128.1 to 210.177.191.254210.177.191.25516,382
200210.177.192.0/18210.177.192.1 to 210.177.255.254210.177.255.25516,382
201210.178.0.0/18210.178.0.1 to 210.178.63.254210.178.63.25516,382
202210.178.64.0/18210.178.64.1 to 210.178.127.254210.178.127.25516,382
203210.178.128.0/18210.178.128.1 to 210.178.191.254210.178.191.25516,382
204210.178.192.0/18210.178.192.1 to 210.178.255.254210.178.255.25516,382
205210.179.0.0/18210.179.0.1 to 210.179.63.254210.179.63.25516,382
206210.179.64.0/18210.179.64.1 to 210.179.127.254210.179.127.25516,382
207210.179.128.0/18210.179.128.1 to 210.179.191.254210.179.191.25516,382
208210.179.192.0/18210.179.192.1 to 210.179.255.254210.179.255.25516,382
209210.180.0.0/18210.180.0.1 to 210.180.63.254210.180.63.25516,382
210210.180.64.0/18210.180.64.1 to 210.180.127.254210.180.127.25516,382
211210.180.128.0/18210.180.128.1 to 210.180.191.254210.180.191.25516,382
212210.180.192.0/18210.180.192.1 to 210.180.255.254210.180.255.25516,382
213210.181.0.0/18210.181.0.1 to 210.181.63.254210.181.63.25516,382
214210.181.64.0/18210.181.64.1 to 210.181.127.254210.181.127.25516,382
215210.181.128.0/18210.181.128.1 to 210.181.191.254210.181.191.25516,382
216210.181.192.0/18210.181.192.1 to 210.181.255.254210.181.255.25516,382
217210.182.0.0/18210.182.0.1 to 210.182.63.254210.182.63.25516,382
218210.182.64.0/18210.182.64.1 to 210.182.127.254210.182.127.25516,382
219210.182.128.0/18210.182.128.1 to 210.182.191.254210.182.191.25516,382
220210.182.192.0/18210.182.192.1 to 210.182.255.254210.182.255.25516,382
221210.183.0.0/18210.183.0.1 to 210.183.63.254210.183.63.25516,382
222210.183.64.0/18210.183.64.1 to 210.183.127.254210.183.127.25516,382
223210.183.128.0/18210.183.128.1 to 210.183.191.254210.183.191.25516,382
224210.183.192.0/18210.183.192.1 to 210.183.255.254210.183.255.25516,382
225210.184.0.0/18210.184.0.1 to 210.184.63.254210.184.63.25516,382
226210.184.64.0/18210.184.64.1 to 210.184.127.254210.184.127.25516,382
227210.184.128.0/18210.184.128.1 to 210.184.191.254210.184.191.25516,382
228210.184.192.0/18210.184.192.1 to 210.184.255.254210.184.255.25516,382
229210.185.0.0/18210.185.0.1 to 210.185.63.254210.185.63.25516,382
230210.185.64.0/18210.185.64.1 to 210.185.127.254210.185.127.25516,382
231210.185.128.0/18210.185.128.1 to 210.185.191.254210.185.191.25516,382
232210.185.192.0/18210.185.192.1 to 210.185.255.254210.185.255.25516,382
233210.186.0.0/18210.186.0.1 to 210.186.63.254210.186.63.25516,382
234210.186.64.0/18210.186.64.1 to 210.186.127.254210.186.127.25516,382
235210.186.128.0/18210.186.128.1 to 210.186.191.254210.186.191.25516,382
236210.186.192.0/18210.186.192.1 to 210.186.255.254210.186.255.25516,382
237210.187.0.0/18210.187.0.1 to 210.187.63.254210.187.63.25516,382
238210.187.64.0/18210.187.64.1 to 210.187.127.254210.187.127.25516,382
239210.187.128.0/18210.187.128.1 to 210.187.191.254210.187.191.25516,382
240210.187.192.0/18210.187.192.1 to 210.187.255.254210.187.255.25516,382
241210.188.0.0/18210.188.0.1 to 210.188.63.254210.188.63.25516,382
242210.188.64.0/18210.188.64.1 to 210.188.127.254210.188.127.25516,382
243210.188.128.0/18210.188.128.1 to 210.188.191.254210.188.191.25516,382
244210.188.192.0/18210.188.192.1 to 210.188.255.254210.188.255.25516,382
245210.189.0.0/18210.189.0.1 to 210.189.63.254210.189.63.25516,382
246210.189.64.0/18210.189.64.1 to 210.189.127.254210.189.127.25516,382
247210.189.128.0/18210.189.128.1 to 210.189.191.254210.189.191.25516,382
248210.189.192.0/18210.189.192.1 to 210.189.255.254210.189.255.25516,382
249210.190.0.0/18210.190.0.1 to 210.190.63.254210.190.63.25516,382
250210.190.64.0/18210.190.64.1 to 210.190.127.254210.190.127.25516,382
251210.190.128.0/18210.190.128.1 to 210.190.191.254210.190.191.25516,382
252210.190.192.0/18210.190.192.1 to 210.190.255.254210.190.255.25516,382
253210.191.0.0/18210.191.0.1 to 210.191.63.254210.191.63.25516,382
254210.191.64.0/18210.191.64.1 to 210.191.127.254210.191.127.25516,382
255210.191.128.0/18210.191.128.1 to 210.191.191.254210.191.191.25516,382
256210.191.192.0/18210.191.192.1 to 210.191.255.254210.191.255.25516,382

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.