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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.

Network17.0.0.0/10
Usable hosts4,194,302
Subnet mask255.192.0.0
Addresses4,194,304
Network address
17.0.0.0
Broadcast address
17.63.255.255
First usable
17.0.0.1
Last usable
17.63.255.254
Usable hosts
4,194,302 (4,194,304 less the network and broadcast addresses)
Subnet mask
255.192.0.0
Wildcard mask
0.63.255.255 (Cisco ACLs, OSPF)
Prefix length
/10
Type
Public public
Old class
A (default /8)
As numbers
Hex 11000000 · Integer 285212672 to 289406975
Reverse DNS zones
0.17.in-addr.arpa
1.17.in-addr.arpa
2.17.in-addr.arpa
3.17.in-addr.arpa
4.17.in-addr.arpa
5.17.in-addr.arpa
6.17.in-addr.arpa
7.17.in-addr.arpa
8.17.in-addr.arpa
9.17.in-addr.arpa
10.17.in-addr.arpa
11.17.in-addr.arpa
12.17.in-addr.arpa
13.17.in-addr.arpa
14.17.in-addr.arpa
15.17.in-addr.arpa
and 48 more
/10 is not on a 8-bit boundary, so it takes 64 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00010001.00000000.00000000.0000000017.0.0.0
Subnet mask11111111.11000000.00000000.00000000255.192.0.0
Network00010001.00000000.00000000.0000000017.0.0.0
Broadcast00010001.00111111.11111111.1111111117.63.255.255
Split into smaller subnets/21
/11 (2)/12 (4)/13 (8)/14 (16)/15 (32)/16 (64)/17 (128)/18 (256)/19 (512)/20 (1,024)/21 (2,048)/22 (4,096)

17.0.0.0/10 makes 2,048 subnets of /21; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
117.0.0.0/2117.0.0.1 to 17.0.7.25417.0.7.2552,046
217.0.8.0/2117.0.8.1 to 17.0.15.25417.0.15.2552,046
317.0.16.0/2117.0.16.1 to 17.0.23.25417.0.23.2552,046
417.0.24.0/2117.0.24.1 to 17.0.31.25417.0.31.2552,046
517.0.32.0/2117.0.32.1 to 17.0.39.25417.0.39.2552,046
617.0.40.0/2117.0.40.1 to 17.0.47.25417.0.47.2552,046
717.0.48.0/2117.0.48.1 to 17.0.55.25417.0.55.2552,046
817.0.56.0/2117.0.56.1 to 17.0.63.25417.0.63.2552,046
917.0.64.0/2117.0.64.1 to 17.0.71.25417.0.71.2552,046
1017.0.72.0/2117.0.72.1 to 17.0.79.25417.0.79.2552,046
1117.0.80.0/2117.0.80.1 to 17.0.87.25417.0.87.2552,046
1217.0.88.0/2117.0.88.1 to 17.0.95.25417.0.95.2552,046
1317.0.96.0/2117.0.96.1 to 17.0.103.25417.0.103.2552,046
1417.0.104.0/2117.0.104.1 to 17.0.111.25417.0.111.2552,046
1517.0.112.0/2117.0.112.1 to 17.0.119.25417.0.119.2552,046
1617.0.120.0/2117.0.120.1 to 17.0.127.25417.0.127.2552,046
1717.0.128.0/2117.0.128.1 to 17.0.135.25417.0.135.2552,046
1817.0.136.0/2117.0.136.1 to 17.0.143.25417.0.143.2552,046
1917.0.144.0/2117.0.144.1 to 17.0.151.25417.0.151.2552,046
2017.0.152.0/2117.0.152.1 to 17.0.159.25417.0.159.2552,046
2117.0.160.0/2117.0.160.1 to 17.0.167.25417.0.167.2552,046
2217.0.168.0/2117.0.168.1 to 17.0.175.25417.0.175.2552,046
2317.0.176.0/2117.0.176.1 to 17.0.183.25417.0.183.2552,046
2417.0.184.0/2117.0.184.1 to 17.0.191.25417.0.191.2552,046
2517.0.192.0/2117.0.192.1 to 17.0.199.25417.0.199.2552,046
2617.0.200.0/2117.0.200.1 to 17.0.207.25417.0.207.2552,046
2717.0.208.0/2117.0.208.1 to 17.0.215.25417.0.215.2552,046
2817.0.216.0/2117.0.216.1 to 17.0.223.25417.0.223.2552,046
2917.0.224.0/2117.0.224.1 to 17.0.231.25417.0.231.2552,046
3017.0.232.0/2117.0.232.1 to 17.0.239.25417.0.239.2552,046
3117.0.240.0/2117.0.240.1 to 17.0.247.25417.0.247.2552,046
3217.0.248.0/2117.0.248.1 to 17.0.255.25417.0.255.2552,046
3317.1.0.0/2117.1.0.1 to 17.1.7.25417.1.7.2552,046
3417.1.8.0/2117.1.8.1 to 17.1.15.25417.1.15.2552,046
3517.1.16.0/2117.1.16.1 to 17.1.23.25417.1.23.2552,046
3617.1.24.0/2117.1.24.1 to 17.1.31.25417.1.31.2552,046
3717.1.32.0/2117.1.32.1 to 17.1.39.25417.1.39.2552,046
3817.1.40.0/2117.1.40.1 to 17.1.47.25417.1.47.2552,046
3917.1.48.0/2117.1.48.1 to 17.1.55.25417.1.55.2552,046
4017.1.56.0/2117.1.56.1 to 17.1.63.25417.1.63.2552,046
4117.1.64.0/2117.1.64.1 to 17.1.71.25417.1.71.2552,046
4217.1.72.0/2117.1.72.1 to 17.1.79.25417.1.79.2552,046
4317.1.80.0/2117.1.80.1 to 17.1.87.25417.1.87.2552,046
4417.1.88.0/2117.1.88.1 to 17.1.95.25417.1.95.2552,046
4517.1.96.0/2117.1.96.1 to 17.1.103.25417.1.103.2552,046
4617.1.104.0/2117.1.104.1 to 17.1.111.25417.1.111.2552,046
4717.1.112.0/2117.1.112.1 to 17.1.119.25417.1.119.2552,046
4817.1.120.0/2117.1.120.1 to 17.1.127.25417.1.127.2552,046
4917.1.128.0/2117.1.128.1 to 17.1.135.25417.1.135.2552,046
5017.1.136.0/2117.1.136.1 to 17.1.143.25417.1.143.2552,046
5117.1.144.0/2117.1.144.1 to 17.1.151.25417.1.151.2552,046
5217.1.152.0/2117.1.152.1 to 17.1.159.25417.1.159.2552,046
5317.1.160.0/2117.1.160.1 to 17.1.167.25417.1.167.2552,046
5417.1.168.0/2117.1.168.1 to 17.1.175.25417.1.175.2552,046
5517.1.176.0/2117.1.176.1 to 17.1.183.25417.1.183.2552,046
5617.1.184.0/2117.1.184.1 to 17.1.191.25417.1.191.2552,046
5717.1.192.0/2117.1.192.1 to 17.1.199.25417.1.199.2552,046
5817.1.200.0/2117.1.200.1 to 17.1.207.25417.1.207.2552,046
5917.1.208.0/2117.1.208.1 to 17.1.215.25417.1.215.2552,046
6017.1.216.0/2117.1.216.1 to 17.1.223.25417.1.223.2552,046
6117.1.224.0/2117.1.224.1 to 17.1.231.25417.1.231.2552,046
6217.1.232.0/2117.1.232.1 to 17.1.239.25417.1.239.2552,046
6317.1.240.0/2117.1.240.1 to 17.1.247.25417.1.247.2552,046
6417.1.248.0/2117.1.248.1 to 17.1.255.25417.1.255.2552,046
6517.2.0.0/2117.2.0.1 to 17.2.7.25417.2.7.2552,046
6617.2.8.0/2117.2.8.1 to 17.2.15.25417.2.15.2552,046
6717.2.16.0/2117.2.16.1 to 17.2.23.25417.2.23.2552,046
6817.2.24.0/2117.2.24.1 to 17.2.31.25417.2.31.2552,046
6917.2.32.0/2117.2.32.1 to 17.2.39.25417.2.39.2552,046
7017.2.40.0/2117.2.40.1 to 17.2.47.25417.2.47.2552,046
7117.2.48.0/2117.2.48.1 to 17.2.55.25417.2.55.2552,046
7217.2.56.0/2117.2.56.1 to 17.2.63.25417.2.63.2552,046
7317.2.64.0/2117.2.64.1 to 17.2.71.25417.2.71.2552,046
7417.2.72.0/2117.2.72.1 to 17.2.79.25417.2.79.2552,046
7517.2.80.0/2117.2.80.1 to 17.2.87.25417.2.87.2552,046
7617.2.88.0/2117.2.88.1 to 17.2.95.25417.2.95.2552,046
7717.2.96.0/2117.2.96.1 to 17.2.103.25417.2.103.2552,046
7817.2.104.0/2117.2.104.1 to 17.2.111.25417.2.111.2552,046
7917.2.112.0/2117.2.112.1 to 17.2.119.25417.2.119.2552,046
8017.2.120.0/2117.2.120.1 to 17.2.127.25417.2.127.2552,046
8117.2.128.0/2117.2.128.1 to 17.2.135.25417.2.135.2552,046
8217.2.136.0/2117.2.136.1 to 17.2.143.25417.2.143.2552,046
8317.2.144.0/2117.2.144.1 to 17.2.151.25417.2.151.2552,046
8417.2.152.0/2117.2.152.1 to 17.2.159.25417.2.159.2552,046
8517.2.160.0/2117.2.160.1 to 17.2.167.25417.2.167.2552,046
8617.2.168.0/2117.2.168.1 to 17.2.175.25417.2.175.2552,046
8717.2.176.0/2117.2.176.1 to 17.2.183.25417.2.183.2552,046
8817.2.184.0/2117.2.184.1 to 17.2.191.25417.2.191.2552,046
8917.2.192.0/2117.2.192.1 to 17.2.199.25417.2.199.2552,046
9017.2.200.0/2117.2.200.1 to 17.2.207.25417.2.207.2552,046
9117.2.208.0/2117.2.208.1 to 17.2.215.25417.2.215.2552,046
9217.2.216.0/2117.2.216.1 to 17.2.223.25417.2.223.2552,046
9317.2.224.0/2117.2.224.1 to 17.2.231.25417.2.231.2552,046
9417.2.232.0/2117.2.232.1 to 17.2.239.25417.2.239.2552,046
9517.2.240.0/2117.2.240.1 to 17.2.247.25417.2.247.2552,046
9617.2.248.0/2117.2.248.1 to 17.2.255.25417.2.255.2552,046
9717.3.0.0/2117.3.0.1 to 17.3.7.25417.3.7.2552,046
9817.3.8.0/2117.3.8.1 to 17.3.15.25417.3.15.2552,046
9917.3.16.0/2117.3.16.1 to 17.3.23.25417.3.23.2552,046
10017.3.24.0/2117.3.24.1 to 17.3.31.25417.3.31.2552,046
10117.3.32.0/2117.3.32.1 to 17.3.39.25417.3.39.2552,046
10217.3.40.0/2117.3.40.1 to 17.3.47.25417.3.47.2552,046
10317.3.48.0/2117.3.48.1 to 17.3.55.25417.3.55.2552,046
10417.3.56.0/2117.3.56.1 to 17.3.63.25417.3.63.2552,046
10517.3.64.0/2117.3.64.1 to 17.3.71.25417.3.71.2552,046
10617.3.72.0/2117.3.72.1 to 17.3.79.25417.3.79.2552,046
10717.3.80.0/2117.3.80.1 to 17.3.87.25417.3.87.2552,046
10817.3.88.0/2117.3.88.1 to 17.3.95.25417.3.95.2552,046
10917.3.96.0/2117.3.96.1 to 17.3.103.25417.3.103.2552,046
11017.3.104.0/2117.3.104.1 to 17.3.111.25417.3.111.2552,046
11117.3.112.0/2117.3.112.1 to 17.3.119.25417.3.119.2552,046
11217.3.120.0/2117.3.120.1 to 17.3.127.25417.3.127.2552,046
11317.3.128.0/2117.3.128.1 to 17.3.135.25417.3.135.2552,046
11417.3.136.0/2117.3.136.1 to 17.3.143.25417.3.143.2552,046
11517.3.144.0/2117.3.144.1 to 17.3.151.25417.3.151.2552,046
11617.3.152.0/2117.3.152.1 to 17.3.159.25417.3.159.2552,046
11717.3.160.0/2117.3.160.1 to 17.3.167.25417.3.167.2552,046
11817.3.168.0/2117.3.168.1 to 17.3.175.25417.3.175.2552,046
11917.3.176.0/2117.3.176.1 to 17.3.183.25417.3.183.2552,046
12017.3.184.0/2117.3.184.1 to 17.3.191.25417.3.191.2552,046
12117.3.192.0/2117.3.192.1 to 17.3.199.25417.3.199.2552,046
12217.3.200.0/2117.3.200.1 to 17.3.207.25417.3.207.2552,046
12317.3.208.0/2117.3.208.1 to 17.3.215.25417.3.215.2552,046
12417.3.216.0/2117.3.216.1 to 17.3.223.25417.3.223.2552,046
12517.3.224.0/2117.3.224.1 to 17.3.231.25417.3.231.2552,046
12617.3.232.0/2117.3.232.1 to 17.3.239.25417.3.239.2552,046
12717.3.240.0/2117.3.240.1 to 17.3.247.25417.3.247.2552,046
12817.3.248.0/2117.3.248.1 to 17.3.255.25417.3.255.2552,046
12917.4.0.0/2117.4.0.1 to 17.4.7.25417.4.7.2552,046
13017.4.8.0/2117.4.8.1 to 17.4.15.25417.4.15.2552,046
13117.4.16.0/2117.4.16.1 to 17.4.23.25417.4.23.2552,046
13217.4.24.0/2117.4.24.1 to 17.4.31.25417.4.31.2552,046
13317.4.32.0/2117.4.32.1 to 17.4.39.25417.4.39.2552,046
13417.4.40.0/2117.4.40.1 to 17.4.47.25417.4.47.2552,046
13517.4.48.0/2117.4.48.1 to 17.4.55.25417.4.55.2552,046
13617.4.56.0/2117.4.56.1 to 17.4.63.25417.4.63.2552,046
13717.4.64.0/2117.4.64.1 to 17.4.71.25417.4.71.2552,046
13817.4.72.0/2117.4.72.1 to 17.4.79.25417.4.79.2552,046
13917.4.80.0/2117.4.80.1 to 17.4.87.25417.4.87.2552,046
14017.4.88.0/2117.4.88.1 to 17.4.95.25417.4.95.2552,046
14117.4.96.0/2117.4.96.1 to 17.4.103.25417.4.103.2552,046
14217.4.104.0/2117.4.104.1 to 17.4.111.25417.4.111.2552,046
14317.4.112.0/2117.4.112.1 to 17.4.119.25417.4.119.2552,046
14417.4.120.0/2117.4.120.1 to 17.4.127.25417.4.127.2552,046
14517.4.128.0/2117.4.128.1 to 17.4.135.25417.4.135.2552,046
14617.4.136.0/2117.4.136.1 to 17.4.143.25417.4.143.2552,046
14717.4.144.0/2117.4.144.1 to 17.4.151.25417.4.151.2552,046
14817.4.152.0/2117.4.152.1 to 17.4.159.25417.4.159.2552,046
14917.4.160.0/2117.4.160.1 to 17.4.167.25417.4.167.2552,046
15017.4.168.0/2117.4.168.1 to 17.4.175.25417.4.175.2552,046
15117.4.176.0/2117.4.176.1 to 17.4.183.25417.4.183.2552,046
15217.4.184.0/2117.4.184.1 to 17.4.191.25417.4.191.2552,046
15317.4.192.0/2117.4.192.1 to 17.4.199.25417.4.199.2552,046
15417.4.200.0/2117.4.200.1 to 17.4.207.25417.4.207.2552,046
15517.4.208.0/2117.4.208.1 to 17.4.215.25417.4.215.2552,046
15617.4.216.0/2117.4.216.1 to 17.4.223.25417.4.223.2552,046
15717.4.224.0/2117.4.224.1 to 17.4.231.25417.4.231.2552,046
15817.4.232.0/2117.4.232.1 to 17.4.239.25417.4.239.2552,046
15917.4.240.0/2117.4.240.1 to 17.4.247.25417.4.247.2552,046
16017.4.248.0/2117.4.248.1 to 17.4.255.25417.4.255.2552,046
16117.5.0.0/2117.5.0.1 to 17.5.7.25417.5.7.2552,046
16217.5.8.0/2117.5.8.1 to 17.5.15.25417.5.15.2552,046
16317.5.16.0/2117.5.16.1 to 17.5.23.25417.5.23.2552,046
16417.5.24.0/2117.5.24.1 to 17.5.31.25417.5.31.2552,046
16517.5.32.0/2117.5.32.1 to 17.5.39.25417.5.39.2552,046
16617.5.40.0/2117.5.40.1 to 17.5.47.25417.5.47.2552,046
16717.5.48.0/2117.5.48.1 to 17.5.55.25417.5.55.2552,046
16817.5.56.0/2117.5.56.1 to 17.5.63.25417.5.63.2552,046
16917.5.64.0/2117.5.64.1 to 17.5.71.25417.5.71.2552,046
17017.5.72.0/2117.5.72.1 to 17.5.79.25417.5.79.2552,046
17117.5.80.0/2117.5.80.1 to 17.5.87.25417.5.87.2552,046
17217.5.88.0/2117.5.88.1 to 17.5.95.25417.5.95.2552,046
17317.5.96.0/2117.5.96.1 to 17.5.103.25417.5.103.2552,046
17417.5.104.0/2117.5.104.1 to 17.5.111.25417.5.111.2552,046
17517.5.112.0/2117.5.112.1 to 17.5.119.25417.5.119.2552,046
17617.5.120.0/2117.5.120.1 to 17.5.127.25417.5.127.2552,046
17717.5.128.0/2117.5.128.1 to 17.5.135.25417.5.135.2552,046
17817.5.136.0/2117.5.136.1 to 17.5.143.25417.5.143.2552,046
17917.5.144.0/2117.5.144.1 to 17.5.151.25417.5.151.2552,046
18017.5.152.0/2117.5.152.1 to 17.5.159.25417.5.159.2552,046
18117.5.160.0/2117.5.160.1 to 17.5.167.25417.5.167.2552,046
18217.5.168.0/2117.5.168.1 to 17.5.175.25417.5.175.2552,046
18317.5.176.0/2117.5.176.1 to 17.5.183.25417.5.183.2552,046
18417.5.184.0/2117.5.184.1 to 17.5.191.25417.5.191.2552,046
18517.5.192.0/2117.5.192.1 to 17.5.199.25417.5.199.2552,046
18617.5.200.0/2117.5.200.1 to 17.5.207.25417.5.207.2552,046
18717.5.208.0/2117.5.208.1 to 17.5.215.25417.5.215.2552,046
18817.5.216.0/2117.5.216.1 to 17.5.223.25417.5.223.2552,046
18917.5.224.0/2117.5.224.1 to 17.5.231.25417.5.231.2552,046
19017.5.232.0/2117.5.232.1 to 17.5.239.25417.5.239.2552,046
19117.5.240.0/2117.5.240.1 to 17.5.247.25417.5.247.2552,046
19217.5.248.0/2117.5.248.1 to 17.5.255.25417.5.255.2552,046
19317.6.0.0/2117.6.0.1 to 17.6.7.25417.6.7.2552,046
19417.6.8.0/2117.6.8.1 to 17.6.15.25417.6.15.2552,046
19517.6.16.0/2117.6.16.1 to 17.6.23.25417.6.23.2552,046
19617.6.24.0/2117.6.24.1 to 17.6.31.25417.6.31.2552,046
19717.6.32.0/2117.6.32.1 to 17.6.39.25417.6.39.2552,046
19817.6.40.0/2117.6.40.1 to 17.6.47.25417.6.47.2552,046
19917.6.48.0/2117.6.48.1 to 17.6.55.25417.6.55.2552,046
20017.6.56.0/2117.6.56.1 to 17.6.63.25417.6.63.2552,046
20117.6.64.0/2117.6.64.1 to 17.6.71.25417.6.71.2552,046
20217.6.72.0/2117.6.72.1 to 17.6.79.25417.6.79.2552,046
20317.6.80.0/2117.6.80.1 to 17.6.87.25417.6.87.2552,046
20417.6.88.0/2117.6.88.1 to 17.6.95.25417.6.95.2552,046
20517.6.96.0/2117.6.96.1 to 17.6.103.25417.6.103.2552,046
20617.6.104.0/2117.6.104.1 to 17.6.111.25417.6.111.2552,046
20717.6.112.0/2117.6.112.1 to 17.6.119.25417.6.119.2552,046
20817.6.120.0/2117.6.120.1 to 17.6.127.25417.6.127.2552,046
20917.6.128.0/2117.6.128.1 to 17.6.135.25417.6.135.2552,046
21017.6.136.0/2117.6.136.1 to 17.6.143.25417.6.143.2552,046
21117.6.144.0/2117.6.144.1 to 17.6.151.25417.6.151.2552,046
21217.6.152.0/2117.6.152.1 to 17.6.159.25417.6.159.2552,046
21317.6.160.0/2117.6.160.1 to 17.6.167.25417.6.167.2552,046
21417.6.168.0/2117.6.168.1 to 17.6.175.25417.6.175.2552,046
21517.6.176.0/2117.6.176.1 to 17.6.183.25417.6.183.2552,046
21617.6.184.0/2117.6.184.1 to 17.6.191.25417.6.191.2552,046
21717.6.192.0/2117.6.192.1 to 17.6.199.25417.6.199.2552,046
21817.6.200.0/2117.6.200.1 to 17.6.207.25417.6.207.2552,046
21917.6.208.0/2117.6.208.1 to 17.6.215.25417.6.215.2552,046
22017.6.216.0/2117.6.216.1 to 17.6.223.25417.6.223.2552,046
22117.6.224.0/2117.6.224.1 to 17.6.231.25417.6.231.2552,046
22217.6.232.0/2117.6.232.1 to 17.6.239.25417.6.239.2552,046
22317.6.240.0/2117.6.240.1 to 17.6.247.25417.6.247.2552,046
22417.6.248.0/2117.6.248.1 to 17.6.255.25417.6.255.2552,046
22517.7.0.0/2117.7.0.1 to 17.7.7.25417.7.7.2552,046
22617.7.8.0/2117.7.8.1 to 17.7.15.25417.7.15.2552,046
22717.7.16.0/2117.7.16.1 to 17.7.23.25417.7.23.2552,046
22817.7.24.0/2117.7.24.1 to 17.7.31.25417.7.31.2552,046
22917.7.32.0/2117.7.32.1 to 17.7.39.25417.7.39.2552,046
23017.7.40.0/2117.7.40.1 to 17.7.47.25417.7.47.2552,046
23117.7.48.0/2117.7.48.1 to 17.7.55.25417.7.55.2552,046
23217.7.56.0/2117.7.56.1 to 17.7.63.25417.7.63.2552,046
23317.7.64.0/2117.7.64.1 to 17.7.71.25417.7.71.2552,046
23417.7.72.0/2117.7.72.1 to 17.7.79.25417.7.79.2552,046
23517.7.80.0/2117.7.80.1 to 17.7.87.25417.7.87.2552,046
23617.7.88.0/2117.7.88.1 to 17.7.95.25417.7.95.2552,046
23717.7.96.0/2117.7.96.1 to 17.7.103.25417.7.103.2552,046
23817.7.104.0/2117.7.104.1 to 17.7.111.25417.7.111.2552,046
23917.7.112.0/2117.7.112.1 to 17.7.119.25417.7.119.2552,046
24017.7.120.0/2117.7.120.1 to 17.7.127.25417.7.127.2552,046
24117.7.128.0/2117.7.128.1 to 17.7.135.25417.7.135.2552,046
24217.7.136.0/2117.7.136.1 to 17.7.143.25417.7.143.2552,046
24317.7.144.0/2117.7.144.1 to 17.7.151.25417.7.151.2552,046
24417.7.152.0/2117.7.152.1 to 17.7.159.25417.7.159.2552,046
24517.7.160.0/2117.7.160.1 to 17.7.167.25417.7.167.2552,046
24617.7.168.0/2117.7.168.1 to 17.7.175.25417.7.175.2552,046
24717.7.176.0/2117.7.176.1 to 17.7.183.25417.7.183.2552,046
24817.7.184.0/2117.7.184.1 to 17.7.191.25417.7.191.2552,046
24917.7.192.0/2117.7.192.1 to 17.7.199.25417.7.199.2552,046
25017.7.200.0/2117.7.200.1 to 17.7.207.25417.7.207.2552,046
25117.7.208.0/2117.7.208.1 to 17.7.215.25417.7.215.2552,046
25217.7.216.0/2117.7.216.1 to 17.7.223.25417.7.223.2552,046
25317.7.224.0/2117.7.224.1 to 17.7.231.25417.7.231.2552,046
25417.7.232.0/2117.7.232.1 to 17.7.239.25417.7.239.2552,046
25517.7.240.0/2117.7.240.1 to 17.7.247.25417.7.247.2552,046
25617.7.248.0/2117.7.248.1 to 17.7.255.25417.7.255.2552,046

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.