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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.

Network25.128.0.0/9
Usable hosts8,388,606
Subnet mask255.128.0.0
Addresses8,388,608
Network address
25.128.0.0
Broadcast address
25.255.255.255
First usable
25.128.0.1
Last usable
25.255.255.254
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 19800000 · Integer 427819008 to 436207615
Reverse DNS zones
128.25.in-addr.arpa
129.25.in-addr.arpa
130.25.in-addr.arpa
131.25.in-addr.arpa
132.25.in-addr.arpa
133.25.in-addr.arpa
134.25.in-addr.arpa
135.25.in-addr.arpa
136.25.in-addr.arpa
137.25.in-addr.arpa
138.25.in-addr.arpa
139.25.in-addr.arpa
140.25.in-addr.arpa
141.25.in-addr.arpa
142.25.in-addr.arpa
143.25.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
Address00011001.10000000.00000000.0000000025.128.0.0
Subnet mask11111111.10000000.00000000.00000000255.128.0.0
Network00011001.10000000.00000000.0000000025.128.0.0
Broadcast00011001.11111111.11111111.1111111125.255.255.255
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)

25.128.0.0/9 makes 512 subnets of /18; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
125.128.0.0/1825.128.0.1 to 25.128.63.25425.128.63.25516,382
225.128.64.0/1825.128.64.1 to 25.128.127.25425.128.127.25516,382
325.128.128.0/1825.128.128.1 to 25.128.191.25425.128.191.25516,382
425.128.192.0/1825.128.192.1 to 25.128.255.25425.128.255.25516,382
525.129.0.0/1825.129.0.1 to 25.129.63.25425.129.63.25516,382
625.129.64.0/1825.129.64.1 to 25.129.127.25425.129.127.25516,382
725.129.128.0/1825.129.128.1 to 25.129.191.25425.129.191.25516,382
825.129.192.0/1825.129.192.1 to 25.129.255.25425.129.255.25516,382
925.130.0.0/1825.130.0.1 to 25.130.63.25425.130.63.25516,382
1025.130.64.0/1825.130.64.1 to 25.130.127.25425.130.127.25516,382
1125.130.128.0/1825.130.128.1 to 25.130.191.25425.130.191.25516,382
1225.130.192.0/1825.130.192.1 to 25.130.255.25425.130.255.25516,382
1325.131.0.0/1825.131.0.1 to 25.131.63.25425.131.63.25516,382
1425.131.64.0/1825.131.64.1 to 25.131.127.25425.131.127.25516,382
1525.131.128.0/1825.131.128.1 to 25.131.191.25425.131.191.25516,382
1625.131.192.0/1825.131.192.1 to 25.131.255.25425.131.255.25516,382
1725.132.0.0/1825.132.0.1 to 25.132.63.25425.132.63.25516,382
1825.132.64.0/1825.132.64.1 to 25.132.127.25425.132.127.25516,382
1925.132.128.0/1825.132.128.1 to 25.132.191.25425.132.191.25516,382
2025.132.192.0/1825.132.192.1 to 25.132.255.25425.132.255.25516,382
2125.133.0.0/1825.133.0.1 to 25.133.63.25425.133.63.25516,382
2225.133.64.0/1825.133.64.1 to 25.133.127.25425.133.127.25516,382
2325.133.128.0/1825.133.128.1 to 25.133.191.25425.133.191.25516,382
2425.133.192.0/1825.133.192.1 to 25.133.255.25425.133.255.25516,382
2525.134.0.0/1825.134.0.1 to 25.134.63.25425.134.63.25516,382
2625.134.64.0/1825.134.64.1 to 25.134.127.25425.134.127.25516,382
2725.134.128.0/1825.134.128.1 to 25.134.191.25425.134.191.25516,382
2825.134.192.0/1825.134.192.1 to 25.134.255.25425.134.255.25516,382
2925.135.0.0/1825.135.0.1 to 25.135.63.25425.135.63.25516,382
3025.135.64.0/1825.135.64.1 to 25.135.127.25425.135.127.25516,382
3125.135.128.0/1825.135.128.1 to 25.135.191.25425.135.191.25516,382
3225.135.192.0/1825.135.192.1 to 25.135.255.25425.135.255.25516,382
3325.136.0.0/1825.136.0.1 to 25.136.63.25425.136.63.25516,382
3425.136.64.0/1825.136.64.1 to 25.136.127.25425.136.127.25516,382
3525.136.128.0/1825.136.128.1 to 25.136.191.25425.136.191.25516,382
3625.136.192.0/1825.136.192.1 to 25.136.255.25425.136.255.25516,382
3725.137.0.0/1825.137.0.1 to 25.137.63.25425.137.63.25516,382
3825.137.64.0/1825.137.64.1 to 25.137.127.25425.137.127.25516,382
3925.137.128.0/1825.137.128.1 to 25.137.191.25425.137.191.25516,382
4025.137.192.0/1825.137.192.1 to 25.137.255.25425.137.255.25516,382
4125.138.0.0/1825.138.0.1 to 25.138.63.25425.138.63.25516,382
4225.138.64.0/1825.138.64.1 to 25.138.127.25425.138.127.25516,382
4325.138.128.0/1825.138.128.1 to 25.138.191.25425.138.191.25516,382
4425.138.192.0/1825.138.192.1 to 25.138.255.25425.138.255.25516,382
4525.139.0.0/1825.139.0.1 to 25.139.63.25425.139.63.25516,382
4625.139.64.0/1825.139.64.1 to 25.139.127.25425.139.127.25516,382
4725.139.128.0/1825.139.128.1 to 25.139.191.25425.139.191.25516,382
4825.139.192.0/1825.139.192.1 to 25.139.255.25425.139.255.25516,382
4925.140.0.0/1825.140.0.1 to 25.140.63.25425.140.63.25516,382
5025.140.64.0/1825.140.64.1 to 25.140.127.25425.140.127.25516,382
5125.140.128.0/1825.140.128.1 to 25.140.191.25425.140.191.25516,382
5225.140.192.0/1825.140.192.1 to 25.140.255.25425.140.255.25516,382
5325.141.0.0/1825.141.0.1 to 25.141.63.25425.141.63.25516,382
5425.141.64.0/1825.141.64.1 to 25.141.127.25425.141.127.25516,382
5525.141.128.0/1825.141.128.1 to 25.141.191.25425.141.191.25516,382
5625.141.192.0/1825.141.192.1 to 25.141.255.25425.141.255.25516,382
5725.142.0.0/1825.142.0.1 to 25.142.63.25425.142.63.25516,382
5825.142.64.0/1825.142.64.1 to 25.142.127.25425.142.127.25516,382
5925.142.128.0/1825.142.128.1 to 25.142.191.25425.142.191.25516,382
6025.142.192.0/1825.142.192.1 to 25.142.255.25425.142.255.25516,382
6125.143.0.0/1825.143.0.1 to 25.143.63.25425.143.63.25516,382
6225.143.64.0/1825.143.64.1 to 25.143.127.25425.143.127.25516,382
6325.143.128.0/1825.143.128.1 to 25.143.191.25425.143.191.25516,382
6425.143.192.0/1825.143.192.1 to 25.143.255.25425.143.255.25516,382
6525.144.0.0/1825.144.0.1 to 25.144.63.25425.144.63.25516,382
6625.144.64.0/1825.144.64.1 to 25.144.127.25425.144.127.25516,382
6725.144.128.0/1825.144.128.1 to 25.144.191.25425.144.191.25516,382
6825.144.192.0/1825.144.192.1 to 25.144.255.25425.144.255.25516,382
6925.145.0.0/1825.145.0.1 to 25.145.63.25425.145.63.25516,382
7025.145.64.0/1825.145.64.1 to 25.145.127.25425.145.127.25516,382
7125.145.128.0/1825.145.128.1 to 25.145.191.25425.145.191.25516,382
7225.145.192.0/1825.145.192.1 to 25.145.255.25425.145.255.25516,382
7325.146.0.0/1825.146.0.1 to 25.146.63.25425.146.63.25516,382
7425.146.64.0/1825.146.64.1 to 25.146.127.25425.146.127.25516,382
7525.146.128.0/1825.146.128.1 to 25.146.191.25425.146.191.25516,382
7625.146.192.0/1825.146.192.1 to 25.146.255.25425.146.255.25516,382
7725.147.0.0/1825.147.0.1 to 25.147.63.25425.147.63.25516,382
7825.147.64.0/1825.147.64.1 to 25.147.127.25425.147.127.25516,382
7925.147.128.0/1825.147.128.1 to 25.147.191.25425.147.191.25516,382
8025.147.192.0/1825.147.192.1 to 25.147.255.25425.147.255.25516,382
8125.148.0.0/1825.148.0.1 to 25.148.63.25425.148.63.25516,382
8225.148.64.0/1825.148.64.1 to 25.148.127.25425.148.127.25516,382
8325.148.128.0/1825.148.128.1 to 25.148.191.25425.148.191.25516,382
8425.148.192.0/1825.148.192.1 to 25.148.255.25425.148.255.25516,382
8525.149.0.0/1825.149.0.1 to 25.149.63.25425.149.63.25516,382
8625.149.64.0/1825.149.64.1 to 25.149.127.25425.149.127.25516,382
8725.149.128.0/1825.149.128.1 to 25.149.191.25425.149.191.25516,382
8825.149.192.0/1825.149.192.1 to 25.149.255.25425.149.255.25516,382
8925.150.0.0/1825.150.0.1 to 25.150.63.25425.150.63.25516,382
9025.150.64.0/1825.150.64.1 to 25.150.127.25425.150.127.25516,382
9125.150.128.0/1825.150.128.1 to 25.150.191.25425.150.191.25516,382
9225.150.192.0/1825.150.192.1 to 25.150.255.25425.150.255.25516,382
9325.151.0.0/1825.151.0.1 to 25.151.63.25425.151.63.25516,382
9425.151.64.0/1825.151.64.1 to 25.151.127.25425.151.127.25516,382
9525.151.128.0/1825.151.128.1 to 25.151.191.25425.151.191.25516,382
9625.151.192.0/1825.151.192.1 to 25.151.255.25425.151.255.25516,382
9725.152.0.0/1825.152.0.1 to 25.152.63.25425.152.63.25516,382
9825.152.64.0/1825.152.64.1 to 25.152.127.25425.152.127.25516,382
9925.152.128.0/1825.152.128.1 to 25.152.191.25425.152.191.25516,382
10025.152.192.0/1825.152.192.1 to 25.152.255.25425.152.255.25516,382
10125.153.0.0/1825.153.0.1 to 25.153.63.25425.153.63.25516,382
10225.153.64.0/1825.153.64.1 to 25.153.127.25425.153.127.25516,382
10325.153.128.0/1825.153.128.1 to 25.153.191.25425.153.191.25516,382
10425.153.192.0/1825.153.192.1 to 25.153.255.25425.153.255.25516,382
10525.154.0.0/1825.154.0.1 to 25.154.63.25425.154.63.25516,382
10625.154.64.0/1825.154.64.1 to 25.154.127.25425.154.127.25516,382
10725.154.128.0/1825.154.128.1 to 25.154.191.25425.154.191.25516,382
10825.154.192.0/1825.154.192.1 to 25.154.255.25425.154.255.25516,382
10925.155.0.0/1825.155.0.1 to 25.155.63.25425.155.63.25516,382
11025.155.64.0/1825.155.64.1 to 25.155.127.25425.155.127.25516,382
11125.155.128.0/1825.155.128.1 to 25.155.191.25425.155.191.25516,382
11225.155.192.0/1825.155.192.1 to 25.155.255.25425.155.255.25516,382
11325.156.0.0/1825.156.0.1 to 25.156.63.25425.156.63.25516,382
11425.156.64.0/1825.156.64.1 to 25.156.127.25425.156.127.25516,382
11525.156.128.0/1825.156.128.1 to 25.156.191.25425.156.191.25516,382
11625.156.192.0/1825.156.192.1 to 25.156.255.25425.156.255.25516,382
11725.157.0.0/1825.157.0.1 to 25.157.63.25425.157.63.25516,382
11825.157.64.0/1825.157.64.1 to 25.157.127.25425.157.127.25516,382
11925.157.128.0/1825.157.128.1 to 25.157.191.25425.157.191.25516,382
12025.157.192.0/1825.157.192.1 to 25.157.255.25425.157.255.25516,382
12125.158.0.0/1825.158.0.1 to 25.158.63.25425.158.63.25516,382
12225.158.64.0/1825.158.64.1 to 25.158.127.25425.158.127.25516,382
12325.158.128.0/1825.158.128.1 to 25.158.191.25425.158.191.25516,382
12425.158.192.0/1825.158.192.1 to 25.158.255.25425.158.255.25516,382
12525.159.0.0/1825.159.0.1 to 25.159.63.25425.159.63.25516,382
12625.159.64.0/1825.159.64.1 to 25.159.127.25425.159.127.25516,382
12725.159.128.0/1825.159.128.1 to 25.159.191.25425.159.191.25516,382
12825.159.192.0/1825.159.192.1 to 25.159.255.25425.159.255.25516,382
12925.160.0.0/1825.160.0.1 to 25.160.63.25425.160.63.25516,382
13025.160.64.0/1825.160.64.1 to 25.160.127.25425.160.127.25516,382
13125.160.128.0/1825.160.128.1 to 25.160.191.25425.160.191.25516,382
13225.160.192.0/1825.160.192.1 to 25.160.255.25425.160.255.25516,382
13325.161.0.0/1825.161.0.1 to 25.161.63.25425.161.63.25516,382
13425.161.64.0/1825.161.64.1 to 25.161.127.25425.161.127.25516,382
13525.161.128.0/1825.161.128.1 to 25.161.191.25425.161.191.25516,382
13625.161.192.0/1825.161.192.1 to 25.161.255.25425.161.255.25516,382
13725.162.0.0/1825.162.0.1 to 25.162.63.25425.162.63.25516,382
13825.162.64.0/1825.162.64.1 to 25.162.127.25425.162.127.25516,382
13925.162.128.0/1825.162.128.1 to 25.162.191.25425.162.191.25516,382
14025.162.192.0/1825.162.192.1 to 25.162.255.25425.162.255.25516,382
14125.163.0.0/1825.163.0.1 to 25.163.63.25425.163.63.25516,382
14225.163.64.0/1825.163.64.1 to 25.163.127.25425.163.127.25516,382
14325.163.128.0/1825.163.128.1 to 25.163.191.25425.163.191.25516,382
14425.163.192.0/1825.163.192.1 to 25.163.255.25425.163.255.25516,382
14525.164.0.0/1825.164.0.1 to 25.164.63.25425.164.63.25516,382
14625.164.64.0/1825.164.64.1 to 25.164.127.25425.164.127.25516,382
14725.164.128.0/1825.164.128.1 to 25.164.191.25425.164.191.25516,382
14825.164.192.0/1825.164.192.1 to 25.164.255.25425.164.255.25516,382
14925.165.0.0/1825.165.0.1 to 25.165.63.25425.165.63.25516,382
15025.165.64.0/1825.165.64.1 to 25.165.127.25425.165.127.25516,382
15125.165.128.0/1825.165.128.1 to 25.165.191.25425.165.191.25516,382
15225.165.192.0/1825.165.192.1 to 25.165.255.25425.165.255.25516,382
15325.166.0.0/1825.166.0.1 to 25.166.63.25425.166.63.25516,382
15425.166.64.0/1825.166.64.1 to 25.166.127.25425.166.127.25516,382
15525.166.128.0/1825.166.128.1 to 25.166.191.25425.166.191.25516,382
15625.166.192.0/1825.166.192.1 to 25.166.255.25425.166.255.25516,382
15725.167.0.0/1825.167.0.1 to 25.167.63.25425.167.63.25516,382
15825.167.64.0/1825.167.64.1 to 25.167.127.25425.167.127.25516,382
15925.167.128.0/1825.167.128.1 to 25.167.191.25425.167.191.25516,382
16025.167.192.0/1825.167.192.1 to 25.167.255.25425.167.255.25516,382
16125.168.0.0/1825.168.0.1 to 25.168.63.25425.168.63.25516,382
16225.168.64.0/1825.168.64.1 to 25.168.127.25425.168.127.25516,382
16325.168.128.0/1825.168.128.1 to 25.168.191.25425.168.191.25516,382
16425.168.192.0/1825.168.192.1 to 25.168.255.25425.168.255.25516,382
16525.169.0.0/1825.169.0.1 to 25.169.63.25425.169.63.25516,382
16625.169.64.0/1825.169.64.1 to 25.169.127.25425.169.127.25516,382
16725.169.128.0/1825.169.128.1 to 25.169.191.25425.169.191.25516,382
16825.169.192.0/1825.169.192.1 to 25.169.255.25425.169.255.25516,382
16925.170.0.0/1825.170.0.1 to 25.170.63.25425.170.63.25516,382
17025.170.64.0/1825.170.64.1 to 25.170.127.25425.170.127.25516,382
17125.170.128.0/1825.170.128.1 to 25.170.191.25425.170.191.25516,382
17225.170.192.0/1825.170.192.1 to 25.170.255.25425.170.255.25516,382
17325.171.0.0/1825.171.0.1 to 25.171.63.25425.171.63.25516,382
17425.171.64.0/1825.171.64.1 to 25.171.127.25425.171.127.25516,382
17525.171.128.0/1825.171.128.1 to 25.171.191.25425.171.191.25516,382
17625.171.192.0/1825.171.192.1 to 25.171.255.25425.171.255.25516,382
17725.172.0.0/1825.172.0.1 to 25.172.63.25425.172.63.25516,382
17825.172.64.0/1825.172.64.1 to 25.172.127.25425.172.127.25516,382
17925.172.128.0/1825.172.128.1 to 25.172.191.25425.172.191.25516,382
18025.172.192.0/1825.172.192.1 to 25.172.255.25425.172.255.25516,382
18125.173.0.0/1825.173.0.1 to 25.173.63.25425.173.63.25516,382
18225.173.64.0/1825.173.64.1 to 25.173.127.25425.173.127.25516,382
18325.173.128.0/1825.173.128.1 to 25.173.191.25425.173.191.25516,382
18425.173.192.0/1825.173.192.1 to 25.173.255.25425.173.255.25516,382
18525.174.0.0/1825.174.0.1 to 25.174.63.25425.174.63.25516,382
18625.174.64.0/1825.174.64.1 to 25.174.127.25425.174.127.25516,382
18725.174.128.0/1825.174.128.1 to 25.174.191.25425.174.191.25516,382
18825.174.192.0/1825.174.192.1 to 25.174.255.25425.174.255.25516,382
18925.175.0.0/1825.175.0.1 to 25.175.63.25425.175.63.25516,382
19025.175.64.0/1825.175.64.1 to 25.175.127.25425.175.127.25516,382
19125.175.128.0/1825.175.128.1 to 25.175.191.25425.175.191.25516,382
19225.175.192.0/1825.175.192.1 to 25.175.255.25425.175.255.25516,382
19325.176.0.0/1825.176.0.1 to 25.176.63.25425.176.63.25516,382
19425.176.64.0/1825.176.64.1 to 25.176.127.25425.176.127.25516,382
19525.176.128.0/1825.176.128.1 to 25.176.191.25425.176.191.25516,382
19625.176.192.0/1825.176.192.1 to 25.176.255.25425.176.255.25516,382
19725.177.0.0/1825.177.0.1 to 25.177.63.25425.177.63.25516,382
19825.177.64.0/1825.177.64.1 to 25.177.127.25425.177.127.25516,382
19925.177.128.0/1825.177.128.1 to 25.177.191.25425.177.191.25516,382
20025.177.192.0/1825.177.192.1 to 25.177.255.25425.177.255.25516,382
20125.178.0.0/1825.178.0.1 to 25.178.63.25425.178.63.25516,382
20225.178.64.0/1825.178.64.1 to 25.178.127.25425.178.127.25516,382
20325.178.128.0/1825.178.128.1 to 25.178.191.25425.178.191.25516,382
20425.178.192.0/1825.178.192.1 to 25.178.255.25425.178.255.25516,382
20525.179.0.0/1825.179.0.1 to 25.179.63.25425.179.63.25516,382
20625.179.64.0/1825.179.64.1 to 25.179.127.25425.179.127.25516,382
20725.179.128.0/1825.179.128.1 to 25.179.191.25425.179.191.25516,382
20825.179.192.0/1825.179.192.1 to 25.179.255.25425.179.255.25516,382
20925.180.0.0/1825.180.0.1 to 25.180.63.25425.180.63.25516,382
21025.180.64.0/1825.180.64.1 to 25.180.127.25425.180.127.25516,382
21125.180.128.0/1825.180.128.1 to 25.180.191.25425.180.191.25516,382
21225.180.192.0/1825.180.192.1 to 25.180.255.25425.180.255.25516,382
21325.181.0.0/1825.181.0.1 to 25.181.63.25425.181.63.25516,382
21425.181.64.0/1825.181.64.1 to 25.181.127.25425.181.127.25516,382
21525.181.128.0/1825.181.128.1 to 25.181.191.25425.181.191.25516,382
21625.181.192.0/1825.181.192.1 to 25.181.255.25425.181.255.25516,382
21725.182.0.0/1825.182.0.1 to 25.182.63.25425.182.63.25516,382
21825.182.64.0/1825.182.64.1 to 25.182.127.25425.182.127.25516,382
21925.182.128.0/1825.182.128.1 to 25.182.191.25425.182.191.25516,382
22025.182.192.0/1825.182.192.1 to 25.182.255.25425.182.255.25516,382
22125.183.0.0/1825.183.0.1 to 25.183.63.25425.183.63.25516,382
22225.183.64.0/1825.183.64.1 to 25.183.127.25425.183.127.25516,382
22325.183.128.0/1825.183.128.1 to 25.183.191.25425.183.191.25516,382
22425.183.192.0/1825.183.192.1 to 25.183.255.25425.183.255.25516,382
22525.184.0.0/1825.184.0.1 to 25.184.63.25425.184.63.25516,382
22625.184.64.0/1825.184.64.1 to 25.184.127.25425.184.127.25516,382
22725.184.128.0/1825.184.128.1 to 25.184.191.25425.184.191.25516,382
22825.184.192.0/1825.184.192.1 to 25.184.255.25425.184.255.25516,382
22925.185.0.0/1825.185.0.1 to 25.185.63.25425.185.63.25516,382
23025.185.64.0/1825.185.64.1 to 25.185.127.25425.185.127.25516,382
23125.185.128.0/1825.185.128.1 to 25.185.191.25425.185.191.25516,382
23225.185.192.0/1825.185.192.1 to 25.185.255.25425.185.255.25516,382
23325.186.0.0/1825.186.0.1 to 25.186.63.25425.186.63.25516,382
23425.186.64.0/1825.186.64.1 to 25.186.127.25425.186.127.25516,382
23525.186.128.0/1825.186.128.1 to 25.186.191.25425.186.191.25516,382
23625.186.192.0/1825.186.192.1 to 25.186.255.25425.186.255.25516,382
23725.187.0.0/1825.187.0.1 to 25.187.63.25425.187.63.25516,382
23825.187.64.0/1825.187.64.1 to 25.187.127.25425.187.127.25516,382
23925.187.128.0/1825.187.128.1 to 25.187.191.25425.187.191.25516,382
24025.187.192.0/1825.187.192.1 to 25.187.255.25425.187.255.25516,382
24125.188.0.0/1825.188.0.1 to 25.188.63.25425.188.63.25516,382
24225.188.64.0/1825.188.64.1 to 25.188.127.25425.188.127.25516,382
24325.188.128.0/1825.188.128.1 to 25.188.191.25425.188.191.25516,382
24425.188.192.0/1825.188.192.1 to 25.188.255.25425.188.255.25516,382
24525.189.0.0/1825.189.0.1 to 25.189.63.25425.189.63.25516,382
24625.189.64.0/1825.189.64.1 to 25.189.127.25425.189.127.25516,382
24725.189.128.0/1825.189.128.1 to 25.189.191.25425.189.191.25516,382
24825.189.192.0/1825.189.192.1 to 25.189.255.25425.189.255.25516,382
24925.190.0.0/1825.190.0.1 to 25.190.63.25425.190.63.25516,382
25025.190.64.0/1825.190.64.1 to 25.190.127.25425.190.127.25516,382
25125.190.128.0/1825.190.128.1 to 25.190.191.25425.190.191.25516,382
25225.190.192.0/1825.190.192.1 to 25.190.255.25425.190.255.25516,382
25325.191.0.0/1825.191.0.1 to 25.191.63.25425.191.63.25516,382
25425.191.64.0/1825.191.64.1 to 25.191.127.25425.191.127.25516,382
25525.191.128.0/1825.191.128.1 to 25.191.191.25425.191.191.25516,382
25625.191.192.0/1825.191.192.1 to 25.191.255.25425.191.255.25516,382

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.