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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.

Network73.128.0.0/9
Usable hosts8,388,606
Subnet mask255.128.0.0
Addresses8,388,608
Network address
73.128.0.0
Broadcast address
73.255.255.255
First usable
73.128.0.1
Last usable
73.255.255.254
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 49800000 · Integer 1233125376 to 1241513983
Reverse DNS zones
128.73.in-addr.arpa
129.73.in-addr.arpa
130.73.in-addr.arpa
131.73.in-addr.arpa
132.73.in-addr.arpa
133.73.in-addr.arpa
134.73.in-addr.arpa
135.73.in-addr.arpa
136.73.in-addr.arpa
137.73.in-addr.arpa
138.73.in-addr.arpa
139.73.in-addr.arpa
140.73.in-addr.arpa
141.73.in-addr.arpa
142.73.in-addr.arpa
143.73.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
Address01001001.10000000.00000000.0000000073.128.0.0
Subnet mask11111111.10000000.00000000.00000000255.128.0.0
Network01001001.10000000.00000000.0000000073.128.0.0
Broadcast01001001.11111111.11111111.1111111173.255.255.255
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)

73.128.0.0/9 makes 512 subnets of /18; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
173.128.0.0/1873.128.0.1 to 73.128.63.25473.128.63.25516,382
273.128.64.0/1873.128.64.1 to 73.128.127.25473.128.127.25516,382
373.128.128.0/1873.128.128.1 to 73.128.191.25473.128.191.25516,382
473.128.192.0/1873.128.192.1 to 73.128.255.25473.128.255.25516,382
573.129.0.0/1873.129.0.1 to 73.129.63.25473.129.63.25516,382
673.129.64.0/1873.129.64.1 to 73.129.127.25473.129.127.25516,382
773.129.128.0/1873.129.128.1 to 73.129.191.25473.129.191.25516,382
873.129.192.0/1873.129.192.1 to 73.129.255.25473.129.255.25516,382
973.130.0.0/1873.130.0.1 to 73.130.63.25473.130.63.25516,382
1073.130.64.0/1873.130.64.1 to 73.130.127.25473.130.127.25516,382
1173.130.128.0/1873.130.128.1 to 73.130.191.25473.130.191.25516,382
1273.130.192.0/1873.130.192.1 to 73.130.255.25473.130.255.25516,382
1373.131.0.0/1873.131.0.1 to 73.131.63.25473.131.63.25516,382
1473.131.64.0/1873.131.64.1 to 73.131.127.25473.131.127.25516,382
1573.131.128.0/1873.131.128.1 to 73.131.191.25473.131.191.25516,382
1673.131.192.0/1873.131.192.1 to 73.131.255.25473.131.255.25516,382
1773.132.0.0/1873.132.0.1 to 73.132.63.25473.132.63.25516,382
1873.132.64.0/1873.132.64.1 to 73.132.127.25473.132.127.25516,382
1973.132.128.0/1873.132.128.1 to 73.132.191.25473.132.191.25516,382
2073.132.192.0/1873.132.192.1 to 73.132.255.25473.132.255.25516,382
2173.133.0.0/1873.133.0.1 to 73.133.63.25473.133.63.25516,382
2273.133.64.0/1873.133.64.1 to 73.133.127.25473.133.127.25516,382
2373.133.128.0/1873.133.128.1 to 73.133.191.25473.133.191.25516,382
2473.133.192.0/1873.133.192.1 to 73.133.255.25473.133.255.25516,382
2573.134.0.0/1873.134.0.1 to 73.134.63.25473.134.63.25516,382
2673.134.64.0/1873.134.64.1 to 73.134.127.25473.134.127.25516,382
2773.134.128.0/1873.134.128.1 to 73.134.191.25473.134.191.25516,382
2873.134.192.0/1873.134.192.1 to 73.134.255.25473.134.255.25516,382
2973.135.0.0/1873.135.0.1 to 73.135.63.25473.135.63.25516,382
3073.135.64.0/1873.135.64.1 to 73.135.127.25473.135.127.25516,382
3173.135.128.0/1873.135.128.1 to 73.135.191.25473.135.191.25516,382
3273.135.192.0/1873.135.192.1 to 73.135.255.25473.135.255.25516,382
3373.136.0.0/1873.136.0.1 to 73.136.63.25473.136.63.25516,382
3473.136.64.0/1873.136.64.1 to 73.136.127.25473.136.127.25516,382
3573.136.128.0/1873.136.128.1 to 73.136.191.25473.136.191.25516,382
3673.136.192.0/1873.136.192.1 to 73.136.255.25473.136.255.25516,382
3773.137.0.0/1873.137.0.1 to 73.137.63.25473.137.63.25516,382
3873.137.64.0/1873.137.64.1 to 73.137.127.25473.137.127.25516,382
3973.137.128.0/1873.137.128.1 to 73.137.191.25473.137.191.25516,382
4073.137.192.0/1873.137.192.1 to 73.137.255.25473.137.255.25516,382
4173.138.0.0/1873.138.0.1 to 73.138.63.25473.138.63.25516,382
4273.138.64.0/1873.138.64.1 to 73.138.127.25473.138.127.25516,382
4373.138.128.0/1873.138.128.1 to 73.138.191.25473.138.191.25516,382
4473.138.192.0/1873.138.192.1 to 73.138.255.25473.138.255.25516,382
4573.139.0.0/1873.139.0.1 to 73.139.63.25473.139.63.25516,382
4673.139.64.0/1873.139.64.1 to 73.139.127.25473.139.127.25516,382
4773.139.128.0/1873.139.128.1 to 73.139.191.25473.139.191.25516,382
4873.139.192.0/1873.139.192.1 to 73.139.255.25473.139.255.25516,382
4973.140.0.0/1873.140.0.1 to 73.140.63.25473.140.63.25516,382
5073.140.64.0/1873.140.64.1 to 73.140.127.25473.140.127.25516,382
5173.140.128.0/1873.140.128.1 to 73.140.191.25473.140.191.25516,382
5273.140.192.0/1873.140.192.1 to 73.140.255.25473.140.255.25516,382
5373.141.0.0/1873.141.0.1 to 73.141.63.25473.141.63.25516,382
5473.141.64.0/1873.141.64.1 to 73.141.127.25473.141.127.25516,382
5573.141.128.0/1873.141.128.1 to 73.141.191.25473.141.191.25516,382
5673.141.192.0/1873.141.192.1 to 73.141.255.25473.141.255.25516,382
5773.142.0.0/1873.142.0.1 to 73.142.63.25473.142.63.25516,382
5873.142.64.0/1873.142.64.1 to 73.142.127.25473.142.127.25516,382
5973.142.128.0/1873.142.128.1 to 73.142.191.25473.142.191.25516,382
6073.142.192.0/1873.142.192.1 to 73.142.255.25473.142.255.25516,382
6173.143.0.0/1873.143.0.1 to 73.143.63.25473.143.63.25516,382
6273.143.64.0/1873.143.64.1 to 73.143.127.25473.143.127.25516,382
6373.143.128.0/1873.143.128.1 to 73.143.191.25473.143.191.25516,382
6473.143.192.0/1873.143.192.1 to 73.143.255.25473.143.255.25516,382
6573.144.0.0/1873.144.0.1 to 73.144.63.25473.144.63.25516,382
6673.144.64.0/1873.144.64.1 to 73.144.127.25473.144.127.25516,382
6773.144.128.0/1873.144.128.1 to 73.144.191.25473.144.191.25516,382
6873.144.192.0/1873.144.192.1 to 73.144.255.25473.144.255.25516,382
6973.145.0.0/1873.145.0.1 to 73.145.63.25473.145.63.25516,382
7073.145.64.0/1873.145.64.1 to 73.145.127.25473.145.127.25516,382
7173.145.128.0/1873.145.128.1 to 73.145.191.25473.145.191.25516,382
7273.145.192.0/1873.145.192.1 to 73.145.255.25473.145.255.25516,382
7373.146.0.0/1873.146.0.1 to 73.146.63.25473.146.63.25516,382
7473.146.64.0/1873.146.64.1 to 73.146.127.25473.146.127.25516,382
7573.146.128.0/1873.146.128.1 to 73.146.191.25473.146.191.25516,382
7673.146.192.0/1873.146.192.1 to 73.146.255.25473.146.255.25516,382
7773.147.0.0/1873.147.0.1 to 73.147.63.25473.147.63.25516,382
7873.147.64.0/1873.147.64.1 to 73.147.127.25473.147.127.25516,382
7973.147.128.0/1873.147.128.1 to 73.147.191.25473.147.191.25516,382
8073.147.192.0/1873.147.192.1 to 73.147.255.25473.147.255.25516,382
8173.148.0.0/1873.148.0.1 to 73.148.63.25473.148.63.25516,382
8273.148.64.0/1873.148.64.1 to 73.148.127.25473.148.127.25516,382
8373.148.128.0/1873.148.128.1 to 73.148.191.25473.148.191.25516,382
8473.148.192.0/1873.148.192.1 to 73.148.255.25473.148.255.25516,382
8573.149.0.0/1873.149.0.1 to 73.149.63.25473.149.63.25516,382
8673.149.64.0/1873.149.64.1 to 73.149.127.25473.149.127.25516,382
8773.149.128.0/1873.149.128.1 to 73.149.191.25473.149.191.25516,382
8873.149.192.0/1873.149.192.1 to 73.149.255.25473.149.255.25516,382
8973.150.0.0/1873.150.0.1 to 73.150.63.25473.150.63.25516,382
9073.150.64.0/1873.150.64.1 to 73.150.127.25473.150.127.25516,382
9173.150.128.0/1873.150.128.1 to 73.150.191.25473.150.191.25516,382
9273.150.192.0/1873.150.192.1 to 73.150.255.25473.150.255.25516,382
9373.151.0.0/1873.151.0.1 to 73.151.63.25473.151.63.25516,382
9473.151.64.0/1873.151.64.1 to 73.151.127.25473.151.127.25516,382
9573.151.128.0/1873.151.128.1 to 73.151.191.25473.151.191.25516,382
9673.151.192.0/1873.151.192.1 to 73.151.255.25473.151.255.25516,382
9773.152.0.0/1873.152.0.1 to 73.152.63.25473.152.63.25516,382
9873.152.64.0/1873.152.64.1 to 73.152.127.25473.152.127.25516,382
9973.152.128.0/1873.152.128.1 to 73.152.191.25473.152.191.25516,382
10073.152.192.0/1873.152.192.1 to 73.152.255.25473.152.255.25516,382
10173.153.0.0/1873.153.0.1 to 73.153.63.25473.153.63.25516,382
10273.153.64.0/1873.153.64.1 to 73.153.127.25473.153.127.25516,382
10373.153.128.0/1873.153.128.1 to 73.153.191.25473.153.191.25516,382
10473.153.192.0/1873.153.192.1 to 73.153.255.25473.153.255.25516,382
10573.154.0.0/1873.154.0.1 to 73.154.63.25473.154.63.25516,382
10673.154.64.0/1873.154.64.1 to 73.154.127.25473.154.127.25516,382
10773.154.128.0/1873.154.128.1 to 73.154.191.25473.154.191.25516,382
10873.154.192.0/1873.154.192.1 to 73.154.255.25473.154.255.25516,382
10973.155.0.0/1873.155.0.1 to 73.155.63.25473.155.63.25516,382
11073.155.64.0/1873.155.64.1 to 73.155.127.25473.155.127.25516,382
11173.155.128.0/1873.155.128.1 to 73.155.191.25473.155.191.25516,382
11273.155.192.0/1873.155.192.1 to 73.155.255.25473.155.255.25516,382
11373.156.0.0/1873.156.0.1 to 73.156.63.25473.156.63.25516,382
11473.156.64.0/1873.156.64.1 to 73.156.127.25473.156.127.25516,382
11573.156.128.0/1873.156.128.1 to 73.156.191.25473.156.191.25516,382
11673.156.192.0/1873.156.192.1 to 73.156.255.25473.156.255.25516,382
11773.157.0.0/1873.157.0.1 to 73.157.63.25473.157.63.25516,382
11873.157.64.0/1873.157.64.1 to 73.157.127.25473.157.127.25516,382
11973.157.128.0/1873.157.128.1 to 73.157.191.25473.157.191.25516,382
12073.157.192.0/1873.157.192.1 to 73.157.255.25473.157.255.25516,382
12173.158.0.0/1873.158.0.1 to 73.158.63.25473.158.63.25516,382
12273.158.64.0/1873.158.64.1 to 73.158.127.25473.158.127.25516,382
12373.158.128.0/1873.158.128.1 to 73.158.191.25473.158.191.25516,382
12473.158.192.0/1873.158.192.1 to 73.158.255.25473.158.255.25516,382
12573.159.0.0/1873.159.0.1 to 73.159.63.25473.159.63.25516,382
12673.159.64.0/1873.159.64.1 to 73.159.127.25473.159.127.25516,382
12773.159.128.0/1873.159.128.1 to 73.159.191.25473.159.191.25516,382
12873.159.192.0/1873.159.192.1 to 73.159.255.25473.159.255.25516,382
12973.160.0.0/1873.160.0.1 to 73.160.63.25473.160.63.25516,382
13073.160.64.0/1873.160.64.1 to 73.160.127.25473.160.127.25516,382
13173.160.128.0/1873.160.128.1 to 73.160.191.25473.160.191.25516,382
13273.160.192.0/1873.160.192.1 to 73.160.255.25473.160.255.25516,382
13373.161.0.0/1873.161.0.1 to 73.161.63.25473.161.63.25516,382
13473.161.64.0/1873.161.64.1 to 73.161.127.25473.161.127.25516,382
13573.161.128.0/1873.161.128.1 to 73.161.191.25473.161.191.25516,382
13673.161.192.0/1873.161.192.1 to 73.161.255.25473.161.255.25516,382
13773.162.0.0/1873.162.0.1 to 73.162.63.25473.162.63.25516,382
13873.162.64.0/1873.162.64.1 to 73.162.127.25473.162.127.25516,382
13973.162.128.0/1873.162.128.1 to 73.162.191.25473.162.191.25516,382
14073.162.192.0/1873.162.192.1 to 73.162.255.25473.162.255.25516,382
14173.163.0.0/1873.163.0.1 to 73.163.63.25473.163.63.25516,382
14273.163.64.0/1873.163.64.1 to 73.163.127.25473.163.127.25516,382
14373.163.128.0/1873.163.128.1 to 73.163.191.25473.163.191.25516,382
14473.163.192.0/1873.163.192.1 to 73.163.255.25473.163.255.25516,382
14573.164.0.0/1873.164.0.1 to 73.164.63.25473.164.63.25516,382
14673.164.64.0/1873.164.64.1 to 73.164.127.25473.164.127.25516,382
14773.164.128.0/1873.164.128.1 to 73.164.191.25473.164.191.25516,382
14873.164.192.0/1873.164.192.1 to 73.164.255.25473.164.255.25516,382
14973.165.0.0/1873.165.0.1 to 73.165.63.25473.165.63.25516,382
15073.165.64.0/1873.165.64.1 to 73.165.127.25473.165.127.25516,382
15173.165.128.0/1873.165.128.1 to 73.165.191.25473.165.191.25516,382
15273.165.192.0/1873.165.192.1 to 73.165.255.25473.165.255.25516,382
15373.166.0.0/1873.166.0.1 to 73.166.63.25473.166.63.25516,382
15473.166.64.0/1873.166.64.1 to 73.166.127.25473.166.127.25516,382
15573.166.128.0/1873.166.128.1 to 73.166.191.25473.166.191.25516,382
15673.166.192.0/1873.166.192.1 to 73.166.255.25473.166.255.25516,382
15773.167.0.0/1873.167.0.1 to 73.167.63.25473.167.63.25516,382
15873.167.64.0/1873.167.64.1 to 73.167.127.25473.167.127.25516,382
15973.167.128.0/1873.167.128.1 to 73.167.191.25473.167.191.25516,382
16073.167.192.0/1873.167.192.1 to 73.167.255.25473.167.255.25516,382
16173.168.0.0/1873.168.0.1 to 73.168.63.25473.168.63.25516,382
16273.168.64.0/1873.168.64.1 to 73.168.127.25473.168.127.25516,382
16373.168.128.0/1873.168.128.1 to 73.168.191.25473.168.191.25516,382
16473.168.192.0/1873.168.192.1 to 73.168.255.25473.168.255.25516,382
16573.169.0.0/1873.169.0.1 to 73.169.63.25473.169.63.25516,382
16673.169.64.0/1873.169.64.1 to 73.169.127.25473.169.127.25516,382
16773.169.128.0/1873.169.128.1 to 73.169.191.25473.169.191.25516,382
16873.169.192.0/1873.169.192.1 to 73.169.255.25473.169.255.25516,382
16973.170.0.0/1873.170.0.1 to 73.170.63.25473.170.63.25516,382
17073.170.64.0/1873.170.64.1 to 73.170.127.25473.170.127.25516,382
17173.170.128.0/1873.170.128.1 to 73.170.191.25473.170.191.25516,382
17273.170.192.0/1873.170.192.1 to 73.170.255.25473.170.255.25516,382
17373.171.0.0/1873.171.0.1 to 73.171.63.25473.171.63.25516,382
17473.171.64.0/1873.171.64.1 to 73.171.127.25473.171.127.25516,382
17573.171.128.0/1873.171.128.1 to 73.171.191.25473.171.191.25516,382
17673.171.192.0/1873.171.192.1 to 73.171.255.25473.171.255.25516,382
17773.172.0.0/1873.172.0.1 to 73.172.63.25473.172.63.25516,382
17873.172.64.0/1873.172.64.1 to 73.172.127.25473.172.127.25516,382
17973.172.128.0/1873.172.128.1 to 73.172.191.25473.172.191.25516,382
18073.172.192.0/1873.172.192.1 to 73.172.255.25473.172.255.25516,382
18173.173.0.0/1873.173.0.1 to 73.173.63.25473.173.63.25516,382
18273.173.64.0/1873.173.64.1 to 73.173.127.25473.173.127.25516,382
18373.173.128.0/1873.173.128.1 to 73.173.191.25473.173.191.25516,382
18473.173.192.0/1873.173.192.1 to 73.173.255.25473.173.255.25516,382
18573.174.0.0/1873.174.0.1 to 73.174.63.25473.174.63.25516,382
18673.174.64.0/1873.174.64.1 to 73.174.127.25473.174.127.25516,382
18773.174.128.0/1873.174.128.1 to 73.174.191.25473.174.191.25516,382
18873.174.192.0/1873.174.192.1 to 73.174.255.25473.174.255.25516,382
18973.175.0.0/1873.175.0.1 to 73.175.63.25473.175.63.25516,382
19073.175.64.0/1873.175.64.1 to 73.175.127.25473.175.127.25516,382
19173.175.128.0/1873.175.128.1 to 73.175.191.25473.175.191.25516,382
19273.175.192.0/1873.175.192.1 to 73.175.255.25473.175.255.25516,382
19373.176.0.0/1873.176.0.1 to 73.176.63.25473.176.63.25516,382
19473.176.64.0/1873.176.64.1 to 73.176.127.25473.176.127.25516,382
19573.176.128.0/1873.176.128.1 to 73.176.191.25473.176.191.25516,382
19673.176.192.0/1873.176.192.1 to 73.176.255.25473.176.255.25516,382
19773.177.0.0/1873.177.0.1 to 73.177.63.25473.177.63.25516,382
19873.177.64.0/1873.177.64.1 to 73.177.127.25473.177.127.25516,382
19973.177.128.0/1873.177.128.1 to 73.177.191.25473.177.191.25516,382
20073.177.192.0/1873.177.192.1 to 73.177.255.25473.177.255.25516,382
20173.178.0.0/1873.178.0.1 to 73.178.63.25473.178.63.25516,382
20273.178.64.0/1873.178.64.1 to 73.178.127.25473.178.127.25516,382
20373.178.128.0/1873.178.128.1 to 73.178.191.25473.178.191.25516,382
20473.178.192.0/1873.178.192.1 to 73.178.255.25473.178.255.25516,382
20573.179.0.0/1873.179.0.1 to 73.179.63.25473.179.63.25516,382
20673.179.64.0/1873.179.64.1 to 73.179.127.25473.179.127.25516,382
20773.179.128.0/1873.179.128.1 to 73.179.191.25473.179.191.25516,382
20873.179.192.0/1873.179.192.1 to 73.179.255.25473.179.255.25516,382
20973.180.0.0/1873.180.0.1 to 73.180.63.25473.180.63.25516,382
21073.180.64.0/1873.180.64.1 to 73.180.127.25473.180.127.25516,382
21173.180.128.0/1873.180.128.1 to 73.180.191.25473.180.191.25516,382
21273.180.192.0/1873.180.192.1 to 73.180.255.25473.180.255.25516,382
21373.181.0.0/1873.181.0.1 to 73.181.63.25473.181.63.25516,382
21473.181.64.0/1873.181.64.1 to 73.181.127.25473.181.127.25516,382
21573.181.128.0/1873.181.128.1 to 73.181.191.25473.181.191.25516,382
21673.181.192.0/1873.181.192.1 to 73.181.255.25473.181.255.25516,382
21773.182.0.0/1873.182.0.1 to 73.182.63.25473.182.63.25516,382
21873.182.64.0/1873.182.64.1 to 73.182.127.25473.182.127.25516,382
21973.182.128.0/1873.182.128.1 to 73.182.191.25473.182.191.25516,382
22073.182.192.0/1873.182.192.1 to 73.182.255.25473.182.255.25516,382
22173.183.0.0/1873.183.0.1 to 73.183.63.25473.183.63.25516,382
22273.183.64.0/1873.183.64.1 to 73.183.127.25473.183.127.25516,382
22373.183.128.0/1873.183.128.1 to 73.183.191.25473.183.191.25516,382
22473.183.192.0/1873.183.192.1 to 73.183.255.25473.183.255.25516,382
22573.184.0.0/1873.184.0.1 to 73.184.63.25473.184.63.25516,382
22673.184.64.0/1873.184.64.1 to 73.184.127.25473.184.127.25516,382
22773.184.128.0/1873.184.128.1 to 73.184.191.25473.184.191.25516,382
22873.184.192.0/1873.184.192.1 to 73.184.255.25473.184.255.25516,382
22973.185.0.0/1873.185.0.1 to 73.185.63.25473.185.63.25516,382
23073.185.64.0/1873.185.64.1 to 73.185.127.25473.185.127.25516,382
23173.185.128.0/1873.185.128.1 to 73.185.191.25473.185.191.25516,382
23273.185.192.0/1873.185.192.1 to 73.185.255.25473.185.255.25516,382
23373.186.0.0/1873.186.0.1 to 73.186.63.25473.186.63.25516,382
23473.186.64.0/1873.186.64.1 to 73.186.127.25473.186.127.25516,382
23573.186.128.0/1873.186.128.1 to 73.186.191.25473.186.191.25516,382
23673.186.192.0/1873.186.192.1 to 73.186.255.25473.186.255.25516,382
23773.187.0.0/1873.187.0.1 to 73.187.63.25473.187.63.25516,382
23873.187.64.0/1873.187.64.1 to 73.187.127.25473.187.127.25516,382
23973.187.128.0/1873.187.128.1 to 73.187.191.25473.187.191.25516,382
24073.187.192.0/1873.187.192.1 to 73.187.255.25473.187.255.25516,382
24173.188.0.0/1873.188.0.1 to 73.188.63.25473.188.63.25516,382
24273.188.64.0/1873.188.64.1 to 73.188.127.25473.188.127.25516,382
24373.188.128.0/1873.188.128.1 to 73.188.191.25473.188.191.25516,382
24473.188.192.0/1873.188.192.1 to 73.188.255.25473.188.255.25516,382
24573.189.0.0/1873.189.0.1 to 73.189.63.25473.189.63.25516,382
24673.189.64.0/1873.189.64.1 to 73.189.127.25473.189.127.25516,382
24773.189.128.0/1873.189.128.1 to 73.189.191.25473.189.191.25516,382
24873.189.192.0/1873.189.192.1 to 73.189.255.25473.189.255.25516,382
24973.190.0.0/1873.190.0.1 to 73.190.63.25473.190.63.25516,382
25073.190.64.0/1873.190.64.1 to 73.190.127.25473.190.127.25516,382
25173.190.128.0/1873.190.128.1 to 73.190.191.25473.190.191.25516,382
25273.190.192.0/1873.190.192.1 to 73.190.255.25473.190.255.25516,382
25373.191.0.0/1873.191.0.1 to 73.191.63.25473.191.63.25516,382
25473.191.64.0/1873.191.64.1 to 73.191.127.25473.191.127.25516,382
25573.191.128.0/1873.191.128.1 to 73.191.191.25473.191.191.25516,382
25673.191.192.0/1873.191.192.1 to 73.191.255.25473.191.255.25516,382

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.