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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.

Network101.128.0.0/9
Usable hosts8,388,606
Subnet mask255.128.0.0
Addresses8,388,608
Network address
101.128.0.0
Broadcast address
101.255.255.255
First usable
101.128.0.1
Last usable
101.255.255.254
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
A (default /8)
As numbers
Hex 65800000 · Integer 1702887424 to 1711276031
Reverse DNS zones
128.101.in-addr.arpa
129.101.in-addr.arpa
130.101.in-addr.arpa
131.101.in-addr.arpa
132.101.in-addr.arpa
133.101.in-addr.arpa
134.101.in-addr.arpa
135.101.in-addr.arpa
136.101.in-addr.arpa
137.101.in-addr.arpa
138.101.in-addr.arpa
139.101.in-addr.arpa
140.101.in-addr.arpa
141.101.in-addr.arpa
142.101.in-addr.arpa
143.101.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
Address01100101.10000000.00000000.00000000101.128.0.0
Subnet mask11111111.10000000.00000000.00000000255.128.0.0
Network01100101.10000000.00000000.00000000101.128.0.0
Broadcast01100101.11111111.11111111.11111111101.255.255.255
Split into smaller subnets/17
/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)

101.128.0.0/9 makes 256 subnets of /17.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1101.128.0.0/17101.128.0.1 to 101.128.127.254101.128.127.25532,766
2101.128.128.0/17101.128.128.1 to 101.128.255.254101.128.255.25532,766
3101.129.0.0/17101.129.0.1 to 101.129.127.254101.129.127.25532,766
4101.129.128.0/17101.129.128.1 to 101.129.255.254101.129.255.25532,766
5101.130.0.0/17101.130.0.1 to 101.130.127.254101.130.127.25532,766
6101.130.128.0/17101.130.128.1 to 101.130.255.254101.130.255.25532,766
7101.131.0.0/17101.131.0.1 to 101.131.127.254101.131.127.25532,766
8101.131.128.0/17101.131.128.1 to 101.131.255.254101.131.255.25532,766
9101.132.0.0/17101.132.0.1 to 101.132.127.254101.132.127.25532,766
10101.132.128.0/17101.132.128.1 to 101.132.255.254101.132.255.25532,766
11101.133.0.0/17101.133.0.1 to 101.133.127.254101.133.127.25532,766
12101.133.128.0/17101.133.128.1 to 101.133.255.254101.133.255.25532,766
13101.134.0.0/17101.134.0.1 to 101.134.127.254101.134.127.25532,766
14101.134.128.0/17101.134.128.1 to 101.134.255.254101.134.255.25532,766
15101.135.0.0/17101.135.0.1 to 101.135.127.254101.135.127.25532,766
16101.135.128.0/17101.135.128.1 to 101.135.255.254101.135.255.25532,766
17101.136.0.0/17101.136.0.1 to 101.136.127.254101.136.127.25532,766
18101.136.128.0/17101.136.128.1 to 101.136.255.254101.136.255.25532,766
19101.137.0.0/17101.137.0.1 to 101.137.127.254101.137.127.25532,766
20101.137.128.0/17101.137.128.1 to 101.137.255.254101.137.255.25532,766
21101.138.0.0/17101.138.0.1 to 101.138.127.254101.138.127.25532,766
22101.138.128.0/17101.138.128.1 to 101.138.255.254101.138.255.25532,766
23101.139.0.0/17101.139.0.1 to 101.139.127.254101.139.127.25532,766
24101.139.128.0/17101.139.128.1 to 101.139.255.254101.139.255.25532,766
25101.140.0.0/17101.140.0.1 to 101.140.127.254101.140.127.25532,766
26101.140.128.0/17101.140.128.1 to 101.140.255.254101.140.255.25532,766
27101.141.0.0/17101.141.0.1 to 101.141.127.254101.141.127.25532,766
28101.141.128.0/17101.141.128.1 to 101.141.255.254101.141.255.25532,766
29101.142.0.0/17101.142.0.1 to 101.142.127.254101.142.127.25532,766
30101.142.128.0/17101.142.128.1 to 101.142.255.254101.142.255.25532,766
31101.143.0.0/17101.143.0.1 to 101.143.127.254101.143.127.25532,766
32101.143.128.0/17101.143.128.1 to 101.143.255.254101.143.255.25532,766
33101.144.0.0/17101.144.0.1 to 101.144.127.254101.144.127.25532,766
34101.144.128.0/17101.144.128.1 to 101.144.255.254101.144.255.25532,766
35101.145.0.0/17101.145.0.1 to 101.145.127.254101.145.127.25532,766
36101.145.128.0/17101.145.128.1 to 101.145.255.254101.145.255.25532,766
37101.146.0.0/17101.146.0.1 to 101.146.127.254101.146.127.25532,766
38101.146.128.0/17101.146.128.1 to 101.146.255.254101.146.255.25532,766
39101.147.0.0/17101.147.0.1 to 101.147.127.254101.147.127.25532,766
40101.147.128.0/17101.147.128.1 to 101.147.255.254101.147.255.25532,766
41101.148.0.0/17101.148.0.1 to 101.148.127.254101.148.127.25532,766
42101.148.128.0/17101.148.128.1 to 101.148.255.254101.148.255.25532,766
43101.149.0.0/17101.149.0.1 to 101.149.127.254101.149.127.25532,766
44101.149.128.0/17101.149.128.1 to 101.149.255.254101.149.255.25532,766
45101.150.0.0/17101.150.0.1 to 101.150.127.254101.150.127.25532,766
46101.150.128.0/17101.150.128.1 to 101.150.255.254101.150.255.25532,766
47101.151.0.0/17101.151.0.1 to 101.151.127.254101.151.127.25532,766
48101.151.128.0/17101.151.128.1 to 101.151.255.254101.151.255.25532,766
49101.152.0.0/17101.152.0.1 to 101.152.127.254101.152.127.25532,766
50101.152.128.0/17101.152.128.1 to 101.152.255.254101.152.255.25532,766
51101.153.0.0/17101.153.0.1 to 101.153.127.254101.153.127.25532,766
52101.153.128.0/17101.153.128.1 to 101.153.255.254101.153.255.25532,766
53101.154.0.0/17101.154.0.1 to 101.154.127.254101.154.127.25532,766
54101.154.128.0/17101.154.128.1 to 101.154.255.254101.154.255.25532,766
55101.155.0.0/17101.155.0.1 to 101.155.127.254101.155.127.25532,766
56101.155.128.0/17101.155.128.1 to 101.155.255.254101.155.255.25532,766
57101.156.0.0/17101.156.0.1 to 101.156.127.254101.156.127.25532,766
58101.156.128.0/17101.156.128.1 to 101.156.255.254101.156.255.25532,766
59101.157.0.0/17101.157.0.1 to 101.157.127.254101.157.127.25532,766
60101.157.128.0/17101.157.128.1 to 101.157.255.254101.157.255.25532,766
61101.158.0.0/17101.158.0.1 to 101.158.127.254101.158.127.25532,766
62101.158.128.0/17101.158.128.1 to 101.158.255.254101.158.255.25532,766
63101.159.0.0/17101.159.0.1 to 101.159.127.254101.159.127.25532,766
64101.159.128.0/17101.159.128.1 to 101.159.255.254101.159.255.25532,766
65101.160.0.0/17101.160.0.1 to 101.160.127.254101.160.127.25532,766
66101.160.128.0/17101.160.128.1 to 101.160.255.254101.160.255.25532,766
67101.161.0.0/17101.161.0.1 to 101.161.127.254101.161.127.25532,766
68101.161.128.0/17101.161.128.1 to 101.161.255.254101.161.255.25532,766
69101.162.0.0/17101.162.0.1 to 101.162.127.254101.162.127.25532,766
70101.162.128.0/17101.162.128.1 to 101.162.255.254101.162.255.25532,766
71101.163.0.0/17101.163.0.1 to 101.163.127.254101.163.127.25532,766
72101.163.128.0/17101.163.128.1 to 101.163.255.254101.163.255.25532,766
73101.164.0.0/17101.164.0.1 to 101.164.127.254101.164.127.25532,766
74101.164.128.0/17101.164.128.1 to 101.164.255.254101.164.255.25532,766
75101.165.0.0/17101.165.0.1 to 101.165.127.254101.165.127.25532,766
76101.165.128.0/17101.165.128.1 to 101.165.255.254101.165.255.25532,766
77101.166.0.0/17101.166.0.1 to 101.166.127.254101.166.127.25532,766
78101.166.128.0/17101.166.128.1 to 101.166.255.254101.166.255.25532,766
79101.167.0.0/17101.167.0.1 to 101.167.127.254101.167.127.25532,766
80101.167.128.0/17101.167.128.1 to 101.167.255.254101.167.255.25532,766
81101.168.0.0/17101.168.0.1 to 101.168.127.254101.168.127.25532,766
82101.168.128.0/17101.168.128.1 to 101.168.255.254101.168.255.25532,766
83101.169.0.0/17101.169.0.1 to 101.169.127.254101.169.127.25532,766
84101.169.128.0/17101.169.128.1 to 101.169.255.254101.169.255.25532,766
85101.170.0.0/17101.170.0.1 to 101.170.127.254101.170.127.25532,766
86101.170.128.0/17101.170.128.1 to 101.170.255.254101.170.255.25532,766
87101.171.0.0/17101.171.0.1 to 101.171.127.254101.171.127.25532,766
88101.171.128.0/17101.171.128.1 to 101.171.255.254101.171.255.25532,766
89101.172.0.0/17101.172.0.1 to 101.172.127.254101.172.127.25532,766
90101.172.128.0/17101.172.128.1 to 101.172.255.254101.172.255.25532,766
91101.173.0.0/17101.173.0.1 to 101.173.127.254101.173.127.25532,766
92101.173.128.0/17101.173.128.1 to 101.173.255.254101.173.255.25532,766
93101.174.0.0/17101.174.0.1 to 101.174.127.254101.174.127.25532,766
94101.174.128.0/17101.174.128.1 to 101.174.255.254101.174.255.25532,766
95101.175.0.0/17101.175.0.1 to 101.175.127.254101.175.127.25532,766
96101.175.128.0/17101.175.128.1 to 101.175.255.254101.175.255.25532,766
97101.176.0.0/17101.176.0.1 to 101.176.127.254101.176.127.25532,766
98101.176.128.0/17101.176.128.1 to 101.176.255.254101.176.255.25532,766
99101.177.0.0/17101.177.0.1 to 101.177.127.254101.177.127.25532,766
100101.177.128.0/17101.177.128.1 to 101.177.255.254101.177.255.25532,766
101101.178.0.0/17101.178.0.1 to 101.178.127.254101.178.127.25532,766
102101.178.128.0/17101.178.128.1 to 101.178.255.254101.178.255.25532,766
103101.179.0.0/17101.179.0.1 to 101.179.127.254101.179.127.25532,766
104101.179.128.0/17101.179.128.1 to 101.179.255.254101.179.255.25532,766
105101.180.0.0/17101.180.0.1 to 101.180.127.254101.180.127.25532,766
106101.180.128.0/17101.180.128.1 to 101.180.255.254101.180.255.25532,766
107101.181.0.0/17101.181.0.1 to 101.181.127.254101.181.127.25532,766
108101.181.128.0/17101.181.128.1 to 101.181.255.254101.181.255.25532,766
109101.182.0.0/17101.182.0.1 to 101.182.127.254101.182.127.25532,766
110101.182.128.0/17101.182.128.1 to 101.182.255.254101.182.255.25532,766
111101.183.0.0/17101.183.0.1 to 101.183.127.254101.183.127.25532,766
112101.183.128.0/17101.183.128.1 to 101.183.255.254101.183.255.25532,766
113101.184.0.0/17101.184.0.1 to 101.184.127.254101.184.127.25532,766
114101.184.128.0/17101.184.128.1 to 101.184.255.254101.184.255.25532,766
115101.185.0.0/17101.185.0.1 to 101.185.127.254101.185.127.25532,766
116101.185.128.0/17101.185.128.1 to 101.185.255.254101.185.255.25532,766
117101.186.0.0/17101.186.0.1 to 101.186.127.254101.186.127.25532,766
118101.186.128.0/17101.186.128.1 to 101.186.255.254101.186.255.25532,766
119101.187.0.0/17101.187.0.1 to 101.187.127.254101.187.127.25532,766
120101.187.128.0/17101.187.128.1 to 101.187.255.254101.187.255.25532,766
121101.188.0.0/17101.188.0.1 to 101.188.127.254101.188.127.25532,766
122101.188.128.0/17101.188.128.1 to 101.188.255.254101.188.255.25532,766
123101.189.0.0/17101.189.0.1 to 101.189.127.254101.189.127.25532,766
124101.189.128.0/17101.189.128.1 to 101.189.255.254101.189.255.25532,766
125101.190.0.0/17101.190.0.1 to 101.190.127.254101.190.127.25532,766
126101.190.128.0/17101.190.128.1 to 101.190.255.254101.190.255.25532,766
127101.191.0.0/17101.191.0.1 to 101.191.127.254101.191.127.25532,766
128101.191.128.0/17101.191.128.1 to 101.191.255.254101.191.255.25532,766
129101.192.0.0/17101.192.0.1 to 101.192.127.254101.192.127.25532,766
130101.192.128.0/17101.192.128.1 to 101.192.255.254101.192.255.25532,766
131101.193.0.0/17101.193.0.1 to 101.193.127.254101.193.127.25532,766
132101.193.128.0/17101.193.128.1 to 101.193.255.254101.193.255.25532,766
133101.194.0.0/17101.194.0.1 to 101.194.127.254101.194.127.25532,766
134101.194.128.0/17101.194.128.1 to 101.194.255.254101.194.255.25532,766
135101.195.0.0/17101.195.0.1 to 101.195.127.254101.195.127.25532,766
136101.195.128.0/17101.195.128.1 to 101.195.255.254101.195.255.25532,766
137101.196.0.0/17101.196.0.1 to 101.196.127.254101.196.127.25532,766
138101.196.128.0/17101.196.128.1 to 101.196.255.254101.196.255.25532,766
139101.197.0.0/17101.197.0.1 to 101.197.127.254101.197.127.25532,766
140101.197.128.0/17101.197.128.1 to 101.197.255.254101.197.255.25532,766
141101.198.0.0/17101.198.0.1 to 101.198.127.254101.198.127.25532,766
142101.198.128.0/17101.198.128.1 to 101.198.255.254101.198.255.25532,766
143101.199.0.0/17101.199.0.1 to 101.199.127.254101.199.127.25532,766
144101.199.128.0/17101.199.128.1 to 101.199.255.254101.199.255.25532,766
145101.200.0.0/17101.200.0.1 to 101.200.127.254101.200.127.25532,766
146101.200.128.0/17101.200.128.1 to 101.200.255.254101.200.255.25532,766
147101.201.0.0/17101.201.0.1 to 101.201.127.254101.201.127.25532,766
148101.201.128.0/17101.201.128.1 to 101.201.255.254101.201.255.25532,766
149101.202.0.0/17101.202.0.1 to 101.202.127.254101.202.127.25532,766
150101.202.128.0/17101.202.128.1 to 101.202.255.254101.202.255.25532,766
151101.203.0.0/17101.203.0.1 to 101.203.127.254101.203.127.25532,766
152101.203.128.0/17101.203.128.1 to 101.203.255.254101.203.255.25532,766
153101.204.0.0/17101.204.0.1 to 101.204.127.254101.204.127.25532,766
154101.204.128.0/17101.204.128.1 to 101.204.255.254101.204.255.25532,766
155101.205.0.0/17101.205.0.1 to 101.205.127.254101.205.127.25532,766
156101.205.128.0/17101.205.128.1 to 101.205.255.254101.205.255.25532,766
157101.206.0.0/17101.206.0.1 to 101.206.127.254101.206.127.25532,766
158101.206.128.0/17101.206.128.1 to 101.206.255.254101.206.255.25532,766
159101.207.0.0/17101.207.0.1 to 101.207.127.254101.207.127.25532,766
160101.207.128.0/17101.207.128.1 to 101.207.255.254101.207.255.25532,766
161101.208.0.0/17101.208.0.1 to 101.208.127.254101.208.127.25532,766
162101.208.128.0/17101.208.128.1 to 101.208.255.254101.208.255.25532,766
163101.209.0.0/17101.209.0.1 to 101.209.127.254101.209.127.25532,766
164101.209.128.0/17101.209.128.1 to 101.209.255.254101.209.255.25532,766
165101.210.0.0/17101.210.0.1 to 101.210.127.254101.210.127.25532,766
166101.210.128.0/17101.210.128.1 to 101.210.255.254101.210.255.25532,766
167101.211.0.0/17101.211.0.1 to 101.211.127.254101.211.127.25532,766
168101.211.128.0/17101.211.128.1 to 101.211.255.254101.211.255.25532,766
169101.212.0.0/17101.212.0.1 to 101.212.127.254101.212.127.25532,766
170101.212.128.0/17101.212.128.1 to 101.212.255.254101.212.255.25532,766
171101.213.0.0/17101.213.0.1 to 101.213.127.254101.213.127.25532,766
172101.213.128.0/17101.213.128.1 to 101.213.255.254101.213.255.25532,766
173101.214.0.0/17101.214.0.1 to 101.214.127.254101.214.127.25532,766
174101.214.128.0/17101.214.128.1 to 101.214.255.254101.214.255.25532,766
175101.215.0.0/17101.215.0.1 to 101.215.127.254101.215.127.25532,766
176101.215.128.0/17101.215.128.1 to 101.215.255.254101.215.255.25532,766
177101.216.0.0/17101.216.0.1 to 101.216.127.254101.216.127.25532,766
178101.216.128.0/17101.216.128.1 to 101.216.255.254101.216.255.25532,766
179101.217.0.0/17101.217.0.1 to 101.217.127.254101.217.127.25532,766
180101.217.128.0/17101.217.128.1 to 101.217.255.254101.217.255.25532,766
181101.218.0.0/17101.218.0.1 to 101.218.127.254101.218.127.25532,766
182101.218.128.0/17101.218.128.1 to 101.218.255.254101.218.255.25532,766
183101.219.0.0/17101.219.0.1 to 101.219.127.254101.219.127.25532,766
184101.219.128.0/17101.219.128.1 to 101.219.255.254101.219.255.25532,766
185101.220.0.0/17101.220.0.1 to 101.220.127.254101.220.127.25532,766
186101.220.128.0/17101.220.128.1 to 101.220.255.254101.220.255.25532,766
187101.221.0.0/17101.221.0.1 to 101.221.127.254101.221.127.25532,766
188101.221.128.0/17101.221.128.1 to 101.221.255.254101.221.255.25532,766
189101.222.0.0/17101.222.0.1 to 101.222.127.254101.222.127.25532,766
190101.222.128.0/17101.222.128.1 to 101.222.255.254101.222.255.25532,766
191101.223.0.0/17101.223.0.1 to 101.223.127.254101.223.127.25532,766
192101.223.128.0/17101.223.128.1 to 101.223.255.254101.223.255.25532,766
193101.224.0.0/17101.224.0.1 to 101.224.127.254101.224.127.25532,766
194101.224.128.0/17101.224.128.1 to 101.224.255.254101.224.255.25532,766
195101.225.0.0/17101.225.0.1 to 101.225.127.254101.225.127.25532,766
196101.225.128.0/17101.225.128.1 to 101.225.255.254101.225.255.25532,766
197101.226.0.0/17101.226.0.1 to 101.226.127.254101.226.127.25532,766
198101.226.128.0/17101.226.128.1 to 101.226.255.254101.226.255.25532,766
199101.227.0.0/17101.227.0.1 to 101.227.127.254101.227.127.25532,766
200101.227.128.0/17101.227.128.1 to 101.227.255.254101.227.255.25532,766
201101.228.0.0/17101.228.0.1 to 101.228.127.254101.228.127.25532,766
202101.228.128.0/17101.228.128.1 to 101.228.255.254101.228.255.25532,766
203101.229.0.0/17101.229.0.1 to 101.229.127.254101.229.127.25532,766
204101.229.128.0/17101.229.128.1 to 101.229.255.254101.229.255.25532,766
205101.230.0.0/17101.230.0.1 to 101.230.127.254101.230.127.25532,766
206101.230.128.0/17101.230.128.1 to 101.230.255.254101.230.255.25532,766
207101.231.0.0/17101.231.0.1 to 101.231.127.254101.231.127.25532,766
208101.231.128.0/17101.231.128.1 to 101.231.255.254101.231.255.25532,766
209101.232.0.0/17101.232.0.1 to 101.232.127.254101.232.127.25532,766
210101.232.128.0/17101.232.128.1 to 101.232.255.254101.232.255.25532,766
211101.233.0.0/17101.233.0.1 to 101.233.127.254101.233.127.25532,766
212101.233.128.0/17101.233.128.1 to 101.233.255.254101.233.255.25532,766
213101.234.0.0/17101.234.0.1 to 101.234.127.254101.234.127.25532,766
214101.234.128.0/17101.234.128.1 to 101.234.255.254101.234.255.25532,766
215101.235.0.0/17101.235.0.1 to 101.235.127.254101.235.127.25532,766
216101.235.128.0/17101.235.128.1 to 101.235.255.254101.235.255.25532,766
217101.236.0.0/17101.236.0.1 to 101.236.127.254101.236.127.25532,766
218101.236.128.0/17101.236.128.1 to 101.236.255.254101.236.255.25532,766
219101.237.0.0/17101.237.0.1 to 101.237.127.254101.237.127.25532,766
220101.237.128.0/17101.237.128.1 to 101.237.255.254101.237.255.25532,766
221101.238.0.0/17101.238.0.1 to 101.238.127.254101.238.127.25532,766
222101.238.128.0/17101.238.128.1 to 101.238.255.254101.238.255.25532,766
223101.239.0.0/17101.239.0.1 to 101.239.127.254101.239.127.25532,766
224101.239.128.0/17101.239.128.1 to 101.239.255.254101.239.255.25532,766
225101.240.0.0/17101.240.0.1 to 101.240.127.254101.240.127.25532,766
226101.240.128.0/17101.240.128.1 to 101.240.255.254101.240.255.25532,766
227101.241.0.0/17101.241.0.1 to 101.241.127.254101.241.127.25532,766
228101.241.128.0/17101.241.128.1 to 101.241.255.254101.241.255.25532,766
229101.242.0.0/17101.242.0.1 to 101.242.127.254101.242.127.25532,766
230101.242.128.0/17101.242.128.1 to 101.242.255.254101.242.255.25532,766
231101.243.0.0/17101.243.0.1 to 101.243.127.254101.243.127.25532,766
232101.243.128.0/17101.243.128.1 to 101.243.255.254101.243.255.25532,766
233101.244.0.0/17101.244.0.1 to 101.244.127.254101.244.127.25532,766
234101.244.128.0/17101.244.128.1 to 101.244.255.254101.244.255.25532,766
235101.245.0.0/17101.245.0.1 to 101.245.127.254101.245.127.25532,766
236101.245.128.0/17101.245.128.1 to 101.245.255.254101.245.255.25532,766
237101.246.0.0/17101.246.0.1 to 101.246.127.254101.246.127.25532,766
238101.246.128.0/17101.246.128.1 to 101.246.255.254101.246.255.25532,766
239101.247.0.0/17101.247.0.1 to 101.247.127.254101.247.127.25532,766
240101.247.128.0/17101.247.128.1 to 101.247.255.254101.247.255.25532,766
241101.248.0.0/17101.248.0.1 to 101.248.127.254101.248.127.25532,766
242101.248.128.0/17101.248.128.1 to 101.248.255.254101.248.255.25532,766
243101.249.0.0/17101.249.0.1 to 101.249.127.254101.249.127.25532,766
244101.249.128.0/17101.249.128.1 to 101.249.255.254101.249.255.25532,766
245101.250.0.0/17101.250.0.1 to 101.250.127.254101.250.127.25532,766
246101.250.128.0/17101.250.128.1 to 101.250.255.254101.250.255.25532,766
247101.251.0.0/17101.251.0.1 to 101.251.127.254101.251.127.25532,766
248101.251.128.0/17101.251.128.1 to 101.251.255.254101.251.255.25532,766
249101.252.0.0/17101.252.0.1 to 101.252.127.254101.252.127.25532,766
250101.252.128.0/17101.252.128.1 to 101.252.255.254101.252.255.25532,766
251101.253.0.0/17101.253.0.1 to 101.253.127.254101.253.127.25532,766
252101.253.128.0/17101.253.128.1 to 101.253.255.254101.253.255.25532,766
253101.254.0.0/17101.254.0.1 to 101.254.127.254101.254.127.25532,766
254101.254.128.0/17101.254.128.1 to 101.254.255.254101.254.255.25532,766
255101.255.0.0/17101.255.0.1 to 101.255.127.254101.255.127.25532,766
256101.255.128.0/17101.255.128.1 to 101.255.255.254101.255.255.25532,766

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.