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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.

Network87.0.0.0/9
Usable hosts8,388,606
Subnet mask255.128.0.0
Addresses8,388,608
Network address
87.0.0.0
Broadcast address
87.127.255.255
First usable
87.0.0.1
Last usable
87.127.255.254
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 57000000 · Integer 1459617792 to 1468006399
Reverse DNS zones
0.87.in-addr.arpa
1.87.in-addr.arpa
2.87.in-addr.arpa
3.87.in-addr.arpa
4.87.in-addr.arpa
5.87.in-addr.arpa
6.87.in-addr.arpa
7.87.in-addr.arpa
8.87.in-addr.arpa
9.87.in-addr.arpa
10.87.in-addr.arpa
11.87.in-addr.arpa
12.87.in-addr.arpa
13.87.in-addr.arpa
14.87.in-addr.arpa
15.87.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
Address01010111.00000000.00000000.0000000087.0.0.0
Subnet mask11111111.10000000.00000000.00000000255.128.0.0
Network01010111.00000000.00000000.0000000087.0.0.0
Broadcast01010111.01111111.11111111.1111111187.127.255.255
Split into smaller subnets/21
/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)

87.0.0.0/9 makes 4,096 subnets of /21; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
187.0.0.0/2187.0.0.1 to 87.0.7.25487.0.7.2552,046
287.0.8.0/2187.0.8.1 to 87.0.15.25487.0.15.2552,046
387.0.16.0/2187.0.16.1 to 87.0.23.25487.0.23.2552,046
487.0.24.0/2187.0.24.1 to 87.0.31.25487.0.31.2552,046
587.0.32.0/2187.0.32.1 to 87.0.39.25487.0.39.2552,046
687.0.40.0/2187.0.40.1 to 87.0.47.25487.0.47.2552,046
787.0.48.0/2187.0.48.1 to 87.0.55.25487.0.55.2552,046
887.0.56.0/2187.0.56.1 to 87.0.63.25487.0.63.2552,046
987.0.64.0/2187.0.64.1 to 87.0.71.25487.0.71.2552,046
1087.0.72.0/2187.0.72.1 to 87.0.79.25487.0.79.2552,046
1187.0.80.0/2187.0.80.1 to 87.0.87.25487.0.87.2552,046
1287.0.88.0/2187.0.88.1 to 87.0.95.25487.0.95.2552,046
1387.0.96.0/2187.0.96.1 to 87.0.103.25487.0.103.2552,046
1487.0.104.0/2187.0.104.1 to 87.0.111.25487.0.111.2552,046
1587.0.112.0/2187.0.112.1 to 87.0.119.25487.0.119.2552,046
1687.0.120.0/2187.0.120.1 to 87.0.127.25487.0.127.2552,046
1787.0.128.0/2187.0.128.1 to 87.0.135.25487.0.135.2552,046
1887.0.136.0/2187.0.136.1 to 87.0.143.25487.0.143.2552,046
1987.0.144.0/2187.0.144.1 to 87.0.151.25487.0.151.2552,046
2087.0.152.0/2187.0.152.1 to 87.0.159.25487.0.159.2552,046
2187.0.160.0/2187.0.160.1 to 87.0.167.25487.0.167.2552,046
2287.0.168.0/2187.0.168.1 to 87.0.175.25487.0.175.2552,046
2387.0.176.0/2187.0.176.1 to 87.0.183.25487.0.183.2552,046
2487.0.184.0/2187.0.184.1 to 87.0.191.25487.0.191.2552,046
2587.0.192.0/2187.0.192.1 to 87.0.199.25487.0.199.2552,046
2687.0.200.0/2187.0.200.1 to 87.0.207.25487.0.207.2552,046
2787.0.208.0/2187.0.208.1 to 87.0.215.25487.0.215.2552,046
2887.0.216.0/2187.0.216.1 to 87.0.223.25487.0.223.2552,046
2987.0.224.0/2187.0.224.1 to 87.0.231.25487.0.231.2552,046
3087.0.232.0/2187.0.232.1 to 87.0.239.25487.0.239.2552,046
3187.0.240.0/2187.0.240.1 to 87.0.247.25487.0.247.2552,046
3287.0.248.0/2187.0.248.1 to 87.0.255.25487.0.255.2552,046
3387.1.0.0/2187.1.0.1 to 87.1.7.25487.1.7.2552,046
3487.1.8.0/2187.1.8.1 to 87.1.15.25487.1.15.2552,046
3587.1.16.0/2187.1.16.1 to 87.1.23.25487.1.23.2552,046
3687.1.24.0/2187.1.24.1 to 87.1.31.25487.1.31.2552,046
3787.1.32.0/2187.1.32.1 to 87.1.39.25487.1.39.2552,046
3887.1.40.0/2187.1.40.1 to 87.1.47.25487.1.47.2552,046
3987.1.48.0/2187.1.48.1 to 87.1.55.25487.1.55.2552,046
4087.1.56.0/2187.1.56.1 to 87.1.63.25487.1.63.2552,046
4187.1.64.0/2187.1.64.1 to 87.1.71.25487.1.71.2552,046
4287.1.72.0/2187.1.72.1 to 87.1.79.25487.1.79.2552,046
4387.1.80.0/2187.1.80.1 to 87.1.87.25487.1.87.2552,046
4487.1.88.0/2187.1.88.1 to 87.1.95.25487.1.95.2552,046
4587.1.96.0/2187.1.96.1 to 87.1.103.25487.1.103.2552,046
4687.1.104.0/2187.1.104.1 to 87.1.111.25487.1.111.2552,046
4787.1.112.0/2187.1.112.1 to 87.1.119.25487.1.119.2552,046
4887.1.120.0/2187.1.120.1 to 87.1.127.25487.1.127.2552,046
4987.1.128.0/2187.1.128.1 to 87.1.135.25487.1.135.2552,046
5087.1.136.0/2187.1.136.1 to 87.1.143.25487.1.143.2552,046
5187.1.144.0/2187.1.144.1 to 87.1.151.25487.1.151.2552,046
5287.1.152.0/2187.1.152.1 to 87.1.159.25487.1.159.2552,046
5387.1.160.0/2187.1.160.1 to 87.1.167.25487.1.167.2552,046
5487.1.168.0/2187.1.168.1 to 87.1.175.25487.1.175.2552,046
5587.1.176.0/2187.1.176.1 to 87.1.183.25487.1.183.2552,046
5687.1.184.0/2187.1.184.1 to 87.1.191.25487.1.191.2552,046
5787.1.192.0/2187.1.192.1 to 87.1.199.25487.1.199.2552,046
5887.1.200.0/2187.1.200.1 to 87.1.207.25487.1.207.2552,046
5987.1.208.0/2187.1.208.1 to 87.1.215.25487.1.215.2552,046
6087.1.216.0/2187.1.216.1 to 87.1.223.25487.1.223.2552,046
6187.1.224.0/2187.1.224.1 to 87.1.231.25487.1.231.2552,046
6287.1.232.0/2187.1.232.1 to 87.1.239.25487.1.239.2552,046
6387.1.240.0/2187.1.240.1 to 87.1.247.25487.1.247.2552,046
6487.1.248.0/2187.1.248.1 to 87.1.255.25487.1.255.2552,046
6587.2.0.0/2187.2.0.1 to 87.2.7.25487.2.7.2552,046
6687.2.8.0/2187.2.8.1 to 87.2.15.25487.2.15.2552,046
6787.2.16.0/2187.2.16.1 to 87.2.23.25487.2.23.2552,046
6887.2.24.0/2187.2.24.1 to 87.2.31.25487.2.31.2552,046
6987.2.32.0/2187.2.32.1 to 87.2.39.25487.2.39.2552,046
7087.2.40.0/2187.2.40.1 to 87.2.47.25487.2.47.2552,046
7187.2.48.0/2187.2.48.1 to 87.2.55.25487.2.55.2552,046
7287.2.56.0/2187.2.56.1 to 87.2.63.25487.2.63.2552,046
7387.2.64.0/2187.2.64.1 to 87.2.71.25487.2.71.2552,046
7487.2.72.0/2187.2.72.1 to 87.2.79.25487.2.79.2552,046
7587.2.80.0/2187.2.80.1 to 87.2.87.25487.2.87.2552,046
7687.2.88.0/2187.2.88.1 to 87.2.95.25487.2.95.2552,046
7787.2.96.0/2187.2.96.1 to 87.2.103.25487.2.103.2552,046
7887.2.104.0/2187.2.104.1 to 87.2.111.25487.2.111.2552,046
7987.2.112.0/2187.2.112.1 to 87.2.119.25487.2.119.2552,046
8087.2.120.0/2187.2.120.1 to 87.2.127.25487.2.127.2552,046
8187.2.128.0/2187.2.128.1 to 87.2.135.25487.2.135.2552,046
8287.2.136.0/2187.2.136.1 to 87.2.143.25487.2.143.2552,046
8387.2.144.0/2187.2.144.1 to 87.2.151.25487.2.151.2552,046
8487.2.152.0/2187.2.152.1 to 87.2.159.25487.2.159.2552,046
8587.2.160.0/2187.2.160.1 to 87.2.167.25487.2.167.2552,046
8687.2.168.0/2187.2.168.1 to 87.2.175.25487.2.175.2552,046
8787.2.176.0/2187.2.176.1 to 87.2.183.25487.2.183.2552,046
8887.2.184.0/2187.2.184.1 to 87.2.191.25487.2.191.2552,046
8987.2.192.0/2187.2.192.1 to 87.2.199.25487.2.199.2552,046
9087.2.200.0/2187.2.200.1 to 87.2.207.25487.2.207.2552,046
9187.2.208.0/2187.2.208.1 to 87.2.215.25487.2.215.2552,046
9287.2.216.0/2187.2.216.1 to 87.2.223.25487.2.223.2552,046
9387.2.224.0/2187.2.224.1 to 87.2.231.25487.2.231.2552,046
9487.2.232.0/2187.2.232.1 to 87.2.239.25487.2.239.2552,046
9587.2.240.0/2187.2.240.1 to 87.2.247.25487.2.247.2552,046
9687.2.248.0/2187.2.248.1 to 87.2.255.25487.2.255.2552,046
9787.3.0.0/2187.3.0.1 to 87.3.7.25487.3.7.2552,046
9887.3.8.0/2187.3.8.1 to 87.3.15.25487.3.15.2552,046
9987.3.16.0/2187.3.16.1 to 87.3.23.25487.3.23.2552,046
10087.3.24.0/2187.3.24.1 to 87.3.31.25487.3.31.2552,046
10187.3.32.0/2187.3.32.1 to 87.3.39.25487.3.39.2552,046
10287.3.40.0/2187.3.40.1 to 87.3.47.25487.3.47.2552,046
10387.3.48.0/2187.3.48.1 to 87.3.55.25487.3.55.2552,046
10487.3.56.0/2187.3.56.1 to 87.3.63.25487.3.63.2552,046
10587.3.64.0/2187.3.64.1 to 87.3.71.25487.3.71.2552,046
10687.3.72.0/2187.3.72.1 to 87.3.79.25487.3.79.2552,046
10787.3.80.0/2187.3.80.1 to 87.3.87.25487.3.87.2552,046
10887.3.88.0/2187.3.88.1 to 87.3.95.25487.3.95.2552,046
10987.3.96.0/2187.3.96.1 to 87.3.103.25487.3.103.2552,046
11087.3.104.0/2187.3.104.1 to 87.3.111.25487.3.111.2552,046
11187.3.112.0/2187.3.112.1 to 87.3.119.25487.3.119.2552,046
11287.3.120.0/2187.3.120.1 to 87.3.127.25487.3.127.2552,046
11387.3.128.0/2187.3.128.1 to 87.3.135.25487.3.135.2552,046
11487.3.136.0/2187.3.136.1 to 87.3.143.25487.3.143.2552,046
11587.3.144.0/2187.3.144.1 to 87.3.151.25487.3.151.2552,046
11687.3.152.0/2187.3.152.1 to 87.3.159.25487.3.159.2552,046
11787.3.160.0/2187.3.160.1 to 87.3.167.25487.3.167.2552,046
11887.3.168.0/2187.3.168.1 to 87.3.175.25487.3.175.2552,046
11987.3.176.0/2187.3.176.1 to 87.3.183.25487.3.183.2552,046
12087.3.184.0/2187.3.184.1 to 87.3.191.25487.3.191.2552,046
12187.3.192.0/2187.3.192.1 to 87.3.199.25487.3.199.2552,046
12287.3.200.0/2187.3.200.1 to 87.3.207.25487.3.207.2552,046
12387.3.208.0/2187.3.208.1 to 87.3.215.25487.3.215.2552,046
12487.3.216.0/2187.3.216.1 to 87.3.223.25487.3.223.2552,046
12587.3.224.0/2187.3.224.1 to 87.3.231.25487.3.231.2552,046
12687.3.232.0/2187.3.232.1 to 87.3.239.25487.3.239.2552,046
12787.3.240.0/2187.3.240.1 to 87.3.247.25487.3.247.2552,046
12887.3.248.0/2187.3.248.1 to 87.3.255.25487.3.255.2552,046
12987.4.0.0/2187.4.0.1 to 87.4.7.25487.4.7.2552,046
13087.4.8.0/2187.4.8.1 to 87.4.15.25487.4.15.2552,046
13187.4.16.0/2187.4.16.1 to 87.4.23.25487.4.23.2552,046
13287.4.24.0/2187.4.24.1 to 87.4.31.25487.4.31.2552,046
13387.4.32.0/2187.4.32.1 to 87.4.39.25487.4.39.2552,046
13487.4.40.0/2187.4.40.1 to 87.4.47.25487.4.47.2552,046
13587.4.48.0/2187.4.48.1 to 87.4.55.25487.4.55.2552,046
13687.4.56.0/2187.4.56.1 to 87.4.63.25487.4.63.2552,046
13787.4.64.0/2187.4.64.1 to 87.4.71.25487.4.71.2552,046
13887.4.72.0/2187.4.72.1 to 87.4.79.25487.4.79.2552,046
13987.4.80.0/2187.4.80.1 to 87.4.87.25487.4.87.2552,046
14087.4.88.0/2187.4.88.1 to 87.4.95.25487.4.95.2552,046
14187.4.96.0/2187.4.96.1 to 87.4.103.25487.4.103.2552,046
14287.4.104.0/2187.4.104.1 to 87.4.111.25487.4.111.2552,046
14387.4.112.0/2187.4.112.1 to 87.4.119.25487.4.119.2552,046
14487.4.120.0/2187.4.120.1 to 87.4.127.25487.4.127.2552,046
14587.4.128.0/2187.4.128.1 to 87.4.135.25487.4.135.2552,046
14687.4.136.0/2187.4.136.1 to 87.4.143.25487.4.143.2552,046
14787.4.144.0/2187.4.144.1 to 87.4.151.25487.4.151.2552,046
14887.4.152.0/2187.4.152.1 to 87.4.159.25487.4.159.2552,046
14987.4.160.0/2187.4.160.1 to 87.4.167.25487.4.167.2552,046
15087.4.168.0/2187.4.168.1 to 87.4.175.25487.4.175.2552,046
15187.4.176.0/2187.4.176.1 to 87.4.183.25487.4.183.2552,046
15287.4.184.0/2187.4.184.1 to 87.4.191.25487.4.191.2552,046
15387.4.192.0/2187.4.192.1 to 87.4.199.25487.4.199.2552,046
15487.4.200.0/2187.4.200.1 to 87.4.207.25487.4.207.2552,046
15587.4.208.0/2187.4.208.1 to 87.4.215.25487.4.215.2552,046
15687.4.216.0/2187.4.216.1 to 87.4.223.25487.4.223.2552,046
15787.4.224.0/2187.4.224.1 to 87.4.231.25487.4.231.2552,046
15887.4.232.0/2187.4.232.1 to 87.4.239.25487.4.239.2552,046
15987.4.240.0/2187.4.240.1 to 87.4.247.25487.4.247.2552,046
16087.4.248.0/2187.4.248.1 to 87.4.255.25487.4.255.2552,046
16187.5.0.0/2187.5.0.1 to 87.5.7.25487.5.7.2552,046
16287.5.8.0/2187.5.8.1 to 87.5.15.25487.5.15.2552,046
16387.5.16.0/2187.5.16.1 to 87.5.23.25487.5.23.2552,046
16487.5.24.0/2187.5.24.1 to 87.5.31.25487.5.31.2552,046
16587.5.32.0/2187.5.32.1 to 87.5.39.25487.5.39.2552,046
16687.5.40.0/2187.5.40.1 to 87.5.47.25487.5.47.2552,046
16787.5.48.0/2187.5.48.1 to 87.5.55.25487.5.55.2552,046
16887.5.56.0/2187.5.56.1 to 87.5.63.25487.5.63.2552,046
16987.5.64.0/2187.5.64.1 to 87.5.71.25487.5.71.2552,046
17087.5.72.0/2187.5.72.1 to 87.5.79.25487.5.79.2552,046
17187.5.80.0/2187.5.80.1 to 87.5.87.25487.5.87.2552,046
17287.5.88.0/2187.5.88.1 to 87.5.95.25487.5.95.2552,046
17387.5.96.0/2187.5.96.1 to 87.5.103.25487.5.103.2552,046
17487.5.104.0/2187.5.104.1 to 87.5.111.25487.5.111.2552,046
17587.5.112.0/2187.5.112.1 to 87.5.119.25487.5.119.2552,046
17687.5.120.0/2187.5.120.1 to 87.5.127.25487.5.127.2552,046
17787.5.128.0/2187.5.128.1 to 87.5.135.25487.5.135.2552,046
17887.5.136.0/2187.5.136.1 to 87.5.143.25487.5.143.2552,046
17987.5.144.0/2187.5.144.1 to 87.5.151.25487.5.151.2552,046
18087.5.152.0/2187.5.152.1 to 87.5.159.25487.5.159.2552,046
18187.5.160.0/2187.5.160.1 to 87.5.167.25487.5.167.2552,046
18287.5.168.0/2187.5.168.1 to 87.5.175.25487.5.175.2552,046
18387.5.176.0/2187.5.176.1 to 87.5.183.25487.5.183.2552,046
18487.5.184.0/2187.5.184.1 to 87.5.191.25487.5.191.2552,046
18587.5.192.0/2187.5.192.1 to 87.5.199.25487.5.199.2552,046
18687.5.200.0/2187.5.200.1 to 87.5.207.25487.5.207.2552,046
18787.5.208.0/2187.5.208.1 to 87.5.215.25487.5.215.2552,046
18887.5.216.0/2187.5.216.1 to 87.5.223.25487.5.223.2552,046
18987.5.224.0/2187.5.224.1 to 87.5.231.25487.5.231.2552,046
19087.5.232.0/2187.5.232.1 to 87.5.239.25487.5.239.2552,046
19187.5.240.0/2187.5.240.1 to 87.5.247.25487.5.247.2552,046
19287.5.248.0/2187.5.248.1 to 87.5.255.25487.5.255.2552,046
19387.6.0.0/2187.6.0.1 to 87.6.7.25487.6.7.2552,046
19487.6.8.0/2187.6.8.1 to 87.6.15.25487.6.15.2552,046
19587.6.16.0/2187.6.16.1 to 87.6.23.25487.6.23.2552,046
19687.6.24.0/2187.6.24.1 to 87.6.31.25487.6.31.2552,046
19787.6.32.0/2187.6.32.1 to 87.6.39.25487.6.39.2552,046
19887.6.40.0/2187.6.40.1 to 87.6.47.25487.6.47.2552,046
19987.6.48.0/2187.6.48.1 to 87.6.55.25487.6.55.2552,046
20087.6.56.0/2187.6.56.1 to 87.6.63.25487.6.63.2552,046
20187.6.64.0/2187.6.64.1 to 87.6.71.25487.6.71.2552,046
20287.6.72.0/2187.6.72.1 to 87.6.79.25487.6.79.2552,046
20387.6.80.0/2187.6.80.1 to 87.6.87.25487.6.87.2552,046
20487.6.88.0/2187.6.88.1 to 87.6.95.25487.6.95.2552,046
20587.6.96.0/2187.6.96.1 to 87.6.103.25487.6.103.2552,046
20687.6.104.0/2187.6.104.1 to 87.6.111.25487.6.111.2552,046
20787.6.112.0/2187.6.112.1 to 87.6.119.25487.6.119.2552,046
20887.6.120.0/2187.6.120.1 to 87.6.127.25487.6.127.2552,046
20987.6.128.0/2187.6.128.1 to 87.6.135.25487.6.135.2552,046
21087.6.136.0/2187.6.136.1 to 87.6.143.25487.6.143.2552,046
21187.6.144.0/2187.6.144.1 to 87.6.151.25487.6.151.2552,046
21287.6.152.0/2187.6.152.1 to 87.6.159.25487.6.159.2552,046
21387.6.160.0/2187.6.160.1 to 87.6.167.25487.6.167.2552,046
21487.6.168.0/2187.6.168.1 to 87.6.175.25487.6.175.2552,046
21587.6.176.0/2187.6.176.1 to 87.6.183.25487.6.183.2552,046
21687.6.184.0/2187.6.184.1 to 87.6.191.25487.6.191.2552,046
21787.6.192.0/2187.6.192.1 to 87.6.199.25487.6.199.2552,046
21887.6.200.0/2187.6.200.1 to 87.6.207.25487.6.207.2552,046
21987.6.208.0/2187.6.208.1 to 87.6.215.25487.6.215.2552,046
22087.6.216.0/2187.6.216.1 to 87.6.223.25487.6.223.2552,046
22187.6.224.0/2187.6.224.1 to 87.6.231.25487.6.231.2552,046
22287.6.232.0/2187.6.232.1 to 87.6.239.25487.6.239.2552,046
22387.6.240.0/2187.6.240.1 to 87.6.247.25487.6.247.2552,046
22487.6.248.0/2187.6.248.1 to 87.6.255.25487.6.255.2552,046
22587.7.0.0/2187.7.0.1 to 87.7.7.25487.7.7.2552,046
22687.7.8.0/2187.7.8.1 to 87.7.15.25487.7.15.2552,046
22787.7.16.0/2187.7.16.1 to 87.7.23.25487.7.23.2552,046
22887.7.24.0/2187.7.24.1 to 87.7.31.25487.7.31.2552,046
22987.7.32.0/2187.7.32.1 to 87.7.39.25487.7.39.2552,046
23087.7.40.0/2187.7.40.1 to 87.7.47.25487.7.47.2552,046
23187.7.48.0/2187.7.48.1 to 87.7.55.25487.7.55.2552,046
23287.7.56.0/2187.7.56.1 to 87.7.63.25487.7.63.2552,046
23387.7.64.0/2187.7.64.1 to 87.7.71.25487.7.71.2552,046
23487.7.72.0/2187.7.72.1 to 87.7.79.25487.7.79.2552,046
23587.7.80.0/2187.7.80.1 to 87.7.87.25487.7.87.2552,046
23687.7.88.0/2187.7.88.1 to 87.7.95.25487.7.95.2552,046
23787.7.96.0/2187.7.96.1 to 87.7.103.25487.7.103.2552,046
23887.7.104.0/2187.7.104.1 to 87.7.111.25487.7.111.2552,046
23987.7.112.0/2187.7.112.1 to 87.7.119.25487.7.119.2552,046
24087.7.120.0/2187.7.120.1 to 87.7.127.25487.7.127.2552,046
24187.7.128.0/2187.7.128.1 to 87.7.135.25487.7.135.2552,046
24287.7.136.0/2187.7.136.1 to 87.7.143.25487.7.143.2552,046
24387.7.144.0/2187.7.144.1 to 87.7.151.25487.7.151.2552,046
24487.7.152.0/2187.7.152.1 to 87.7.159.25487.7.159.2552,046
24587.7.160.0/2187.7.160.1 to 87.7.167.25487.7.167.2552,046
24687.7.168.0/2187.7.168.1 to 87.7.175.25487.7.175.2552,046
24787.7.176.0/2187.7.176.1 to 87.7.183.25487.7.183.2552,046
24887.7.184.0/2187.7.184.1 to 87.7.191.25487.7.191.2552,046
24987.7.192.0/2187.7.192.1 to 87.7.199.25487.7.199.2552,046
25087.7.200.0/2187.7.200.1 to 87.7.207.25487.7.207.2552,046
25187.7.208.0/2187.7.208.1 to 87.7.215.25487.7.215.2552,046
25287.7.216.0/2187.7.216.1 to 87.7.223.25487.7.223.2552,046
25387.7.224.0/2187.7.224.1 to 87.7.231.25487.7.231.2552,046
25487.7.232.0/2187.7.232.1 to 87.7.239.25487.7.239.2552,046
25587.7.240.0/2187.7.240.1 to 87.7.247.25487.7.247.2552,046
25687.7.248.0/2187.7.248.1 to 87.7.255.25487.7.255.2552,046

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.