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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/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)

25.128.0.0/9 makes 4,096 subnets of /21; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
125.128.0.0/2125.128.0.1 to 25.128.7.25425.128.7.2552,046
225.128.8.0/2125.128.8.1 to 25.128.15.25425.128.15.2552,046
325.128.16.0/2125.128.16.1 to 25.128.23.25425.128.23.2552,046
425.128.24.0/2125.128.24.1 to 25.128.31.25425.128.31.2552,046
525.128.32.0/2125.128.32.1 to 25.128.39.25425.128.39.2552,046
625.128.40.0/2125.128.40.1 to 25.128.47.25425.128.47.2552,046
725.128.48.0/2125.128.48.1 to 25.128.55.25425.128.55.2552,046
825.128.56.0/2125.128.56.1 to 25.128.63.25425.128.63.2552,046
925.128.64.0/2125.128.64.1 to 25.128.71.25425.128.71.2552,046
1025.128.72.0/2125.128.72.1 to 25.128.79.25425.128.79.2552,046
1125.128.80.0/2125.128.80.1 to 25.128.87.25425.128.87.2552,046
1225.128.88.0/2125.128.88.1 to 25.128.95.25425.128.95.2552,046
1325.128.96.0/2125.128.96.1 to 25.128.103.25425.128.103.2552,046
1425.128.104.0/2125.128.104.1 to 25.128.111.25425.128.111.2552,046
1525.128.112.0/2125.128.112.1 to 25.128.119.25425.128.119.2552,046
1625.128.120.0/2125.128.120.1 to 25.128.127.25425.128.127.2552,046
1725.128.128.0/2125.128.128.1 to 25.128.135.25425.128.135.2552,046
1825.128.136.0/2125.128.136.1 to 25.128.143.25425.128.143.2552,046
1925.128.144.0/2125.128.144.1 to 25.128.151.25425.128.151.2552,046
2025.128.152.0/2125.128.152.1 to 25.128.159.25425.128.159.2552,046
2125.128.160.0/2125.128.160.1 to 25.128.167.25425.128.167.2552,046
2225.128.168.0/2125.128.168.1 to 25.128.175.25425.128.175.2552,046
2325.128.176.0/2125.128.176.1 to 25.128.183.25425.128.183.2552,046
2425.128.184.0/2125.128.184.1 to 25.128.191.25425.128.191.2552,046
2525.128.192.0/2125.128.192.1 to 25.128.199.25425.128.199.2552,046
2625.128.200.0/2125.128.200.1 to 25.128.207.25425.128.207.2552,046
2725.128.208.0/2125.128.208.1 to 25.128.215.25425.128.215.2552,046
2825.128.216.0/2125.128.216.1 to 25.128.223.25425.128.223.2552,046
2925.128.224.0/2125.128.224.1 to 25.128.231.25425.128.231.2552,046
3025.128.232.0/2125.128.232.1 to 25.128.239.25425.128.239.2552,046
3125.128.240.0/2125.128.240.1 to 25.128.247.25425.128.247.2552,046
3225.128.248.0/2125.128.248.1 to 25.128.255.25425.128.255.2552,046
3325.129.0.0/2125.129.0.1 to 25.129.7.25425.129.7.2552,046
3425.129.8.0/2125.129.8.1 to 25.129.15.25425.129.15.2552,046
3525.129.16.0/2125.129.16.1 to 25.129.23.25425.129.23.2552,046
3625.129.24.0/2125.129.24.1 to 25.129.31.25425.129.31.2552,046
3725.129.32.0/2125.129.32.1 to 25.129.39.25425.129.39.2552,046
3825.129.40.0/2125.129.40.1 to 25.129.47.25425.129.47.2552,046
3925.129.48.0/2125.129.48.1 to 25.129.55.25425.129.55.2552,046
4025.129.56.0/2125.129.56.1 to 25.129.63.25425.129.63.2552,046
4125.129.64.0/2125.129.64.1 to 25.129.71.25425.129.71.2552,046
4225.129.72.0/2125.129.72.1 to 25.129.79.25425.129.79.2552,046
4325.129.80.0/2125.129.80.1 to 25.129.87.25425.129.87.2552,046
4425.129.88.0/2125.129.88.1 to 25.129.95.25425.129.95.2552,046
4525.129.96.0/2125.129.96.1 to 25.129.103.25425.129.103.2552,046
4625.129.104.0/2125.129.104.1 to 25.129.111.25425.129.111.2552,046
4725.129.112.0/2125.129.112.1 to 25.129.119.25425.129.119.2552,046
4825.129.120.0/2125.129.120.1 to 25.129.127.25425.129.127.2552,046
4925.129.128.0/2125.129.128.1 to 25.129.135.25425.129.135.2552,046
5025.129.136.0/2125.129.136.1 to 25.129.143.25425.129.143.2552,046
5125.129.144.0/2125.129.144.1 to 25.129.151.25425.129.151.2552,046
5225.129.152.0/2125.129.152.1 to 25.129.159.25425.129.159.2552,046
5325.129.160.0/2125.129.160.1 to 25.129.167.25425.129.167.2552,046
5425.129.168.0/2125.129.168.1 to 25.129.175.25425.129.175.2552,046
5525.129.176.0/2125.129.176.1 to 25.129.183.25425.129.183.2552,046
5625.129.184.0/2125.129.184.1 to 25.129.191.25425.129.191.2552,046
5725.129.192.0/2125.129.192.1 to 25.129.199.25425.129.199.2552,046
5825.129.200.0/2125.129.200.1 to 25.129.207.25425.129.207.2552,046
5925.129.208.0/2125.129.208.1 to 25.129.215.25425.129.215.2552,046
6025.129.216.0/2125.129.216.1 to 25.129.223.25425.129.223.2552,046
6125.129.224.0/2125.129.224.1 to 25.129.231.25425.129.231.2552,046
6225.129.232.0/2125.129.232.1 to 25.129.239.25425.129.239.2552,046
6325.129.240.0/2125.129.240.1 to 25.129.247.25425.129.247.2552,046
6425.129.248.0/2125.129.248.1 to 25.129.255.25425.129.255.2552,046
6525.130.0.0/2125.130.0.1 to 25.130.7.25425.130.7.2552,046
6625.130.8.0/2125.130.8.1 to 25.130.15.25425.130.15.2552,046
6725.130.16.0/2125.130.16.1 to 25.130.23.25425.130.23.2552,046
6825.130.24.0/2125.130.24.1 to 25.130.31.25425.130.31.2552,046
6925.130.32.0/2125.130.32.1 to 25.130.39.25425.130.39.2552,046
7025.130.40.0/2125.130.40.1 to 25.130.47.25425.130.47.2552,046
7125.130.48.0/2125.130.48.1 to 25.130.55.25425.130.55.2552,046
7225.130.56.0/2125.130.56.1 to 25.130.63.25425.130.63.2552,046
7325.130.64.0/2125.130.64.1 to 25.130.71.25425.130.71.2552,046
7425.130.72.0/2125.130.72.1 to 25.130.79.25425.130.79.2552,046
7525.130.80.0/2125.130.80.1 to 25.130.87.25425.130.87.2552,046
7625.130.88.0/2125.130.88.1 to 25.130.95.25425.130.95.2552,046
7725.130.96.0/2125.130.96.1 to 25.130.103.25425.130.103.2552,046
7825.130.104.0/2125.130.104.1 to 25.130.111.25425.130.111.2552,046
7925.130.112.0/2125.130.112.1 to 25.130.119.25425.130.119.2552,046
8025.130.120.0/2125.130.120.1 to 25.130.127.25425.130.127.2552,046
8125.130.128.0/2125.130.128.1 to 25.130.135.25425.130.135.2552,046
8225.130.136.0/2125.130.136.1 to 25.130.143.25425.130.143.2552,046
8325.130.144.0/2125.130.144.1 to 25.130.151.25425.130.151.2552,046
8425.130.152.0/2125.130.152.1 to 25.130.159.25425.130.159.2552,046
8525.130.160.0/2125.130.160.1 to 25.130.167.25425.130.167.2552,046
8625.130.168.0/2125.130.168.1 to 25.130.175.25425.130.175.2552,046
8725.130.176.0/2125.130.176.1 to 25.130.183.25425.130.183.2552,046
8825.130.184.0/2125.130.184.1 to 25.130.191.25425.130.191.2552,046
8925.130.192.0/2125.130.192.1 to 25.130.199.25425.130.199.2552,046
9025.130.200.0/2125.130.200.1 to 25.130.207.25425.130.207.2552,046
9125.130.208.0/2125.130.208.1 to 25.130.215.25425.130.215.2552,046
9225.130.216.0/2125.130.216.1 to 25.130.223.25425.130.223.2552,046
9325.130.224.0/2125.130.224.1 to 25.130.231.25425.130.231.2552,046
9425.130.232.0/2125.130.232.1 to 25.130.239.25425.130.239.2552,046
9525.130.240.0/2125.130.240.1 to 25.130.247.25425.130.247.2552,046
9625.130.248.0/2125.130.248.1 to 25.130.255.25425.130.255.2552,046
9725.131.0.0/2125.131.0.1 to 25.131.7.25425.131.7.2552,046
9825.131.8.0/2125.131.8.1 to 25.131.15.25425.131.15.2552,046
9925.131.16.0/2125.131.16.1 to 25.131.23.25425.131.23.2552,046
10025.131.24.0/2125.131.24.1 to 25.131.31.25425.131.31.2552,046
10125.131.32.0/2125.131.32.1 to 25.131.39.25425.131.39.2552,046
10225.131.40.0/2125.131.40.1 to 25.131.47.25425.131.47.2552,046
10325.131.48.0/2125.131.48.1 to 25.131.55.25425.131.55.2552,046
10425.131.56.0/2125.131.56.1 to 25.131.63.25425.131.63.2552,046
10525.131.64.0/2125.131.64.1 to 25.131.71.25425.131.71.2552,046
10625.131.72.0/2125.131.72.1 to 25.131.79.25425.131.79.2552,046
10725.131.80.0/2125.131.80.1 to 25.131.87.25425.131.87.2552,046
10825.131.88.0/2125.131.88.1 to 25.131.95.25425.131.95.2552,046
10925.131.96.0/2125.131.96.1 to 25.131.103.25425.131.103.2552,046
11025.131.104.0/2125.131.104.1 to 25.131.111.25425.131.111.2552,046
11125.131.112.0/2125.131.112.1 to 25.131.119.25425.131.119.2552,046
11225.131.120.0/2125.131.120.1 to 25.131.127.25425.131.127.2552,046
11325.131.128.0/2125.131.128.1 to 25.131.135.25425.131.135.2552,046
11425.131.136.0/2125.131.136.1 to 25.131.143.25425.131.143.2552,046
11525.131.144.0/2125.131.144.1 to 25.131.151.25425.131.151.2552,046
11625.131.152.0/2125.131.152.1 to 25.131.159.25425.131.159.2552,046
11725.131.160.0/2125.131.160.1 to 25.131.167.25425.131.167.2552,046
11825.131.168.0/2125.131.168.1 to 25.131.175.25425.131.175.2552,046
11925.131.176.0/2125.131.176.1 to 25.131.183.25425.131.183.2552,046
12025.131.184.0/2125.131.184.1 to 25.131.191.25425.131.191.2552,046
12125.131.192.0/2125.131.192.1 to 25.131.199.25425.131.199.2552,046
12225.131.200.0/2125.131.200.1 to 25.131.207.25425.131.207.2552,046
12325.131.208.0/2125.131.208.1 to 25.131.215.25425.131.215.2552,046
12425.131.216.0/2125.131.216.1 to 25.131.223.25425.131.223.2552,046
12525.131.224.0/2125.131.224.1 to 25.131.231.25425.131.231.2552,046
12625.131.232.0/2125.131.232.1 to 25.131.239.25425.131.239.2552,046
12725.131.240.0/2125.131.240.1 to 25.131.247.25425.131.247.2552,046
12825.131.248.0/2125.131.248.1 to 25.131.255.25425.131.255.2552,046
12925.132.0.0/2125.132.0.1 to 25.132.7.25425.132.7.2552,046
13025.132.8.0/2125.132.8.1 to 25.132.15.25425.132.15.2552,046
13125.132.16.0/2125.132.16.1 to 25.132.23.25425.132.23.2552,046
13225.132.24.0/2125.132.24.1 to 25.132.31.25425.132.31.2552,046
13325.132.32.0/2125.132.32.1 to 25.132.39.25425.132.39.2552,046
13425.132.40.0/2125.132.40.1 to 25.132.47.25425.132.47.2552,046
13525.132.48.0/2125.132.48.1 to 25.132.55.25425.132.55.2552,046
13625.132.56.0/2125.132.56.1 to 25.132.63.25425.132.63.2552,046
13725.132.64.0/2125.132.64.1 to 25.132.71.25425.132.71.2552,046
13825.132.72.0/2125.132.72.1 to 25.132.79.25425.132.79.2552,046
13925.132.80.0/2125.132.80.1 to 25.132.87.25425.132.87.2552,046
14025.132.88.0/2125.132.88.1 to 25.132.95.25425.132.95.2552,046
14125.132.96.0/2125.132.96.1 to 25.132.103.25425.132.103.2552,046
14225.132.104.0/2125.132.104.1 to 25.132.111.25425.132.111.2552,046
14325.132.112.0/2125.132.112.1 to 25.132.119.25425.132.119.2552,046
14425.132.120.0/2125.132.120.1 to 25.132.127.25425.132.127.2552,046
14525.132.128.0/2125.132.128.1 to 25.132.135.25425.132.135.2552,046
14625.132.136.0/2125.132.136.1 to 25.132.143.25425.132.143.2552,046
14725.132.144.0/2125.132.144.1 to 25.132.151.25425.132.151.2552,046
14825.132.152.0/2125.132.152.1 to 25.132.159.25425.132.159.2552,046
14925.132.160.0/2125.132.160.1 to 25.132.167.25425.132.167.2552,046
15025.132.168.0/2125.132.168.1 to 25.132.175.25425.132.175.2552,046
15125.132.176.0/2125.132.176.1 to 25.132.183.25425.132.183.2552,046
15225.132.184.0/2125.132.184.1 to 25.132.191.25425.132.191.2552,046
15325.132.192.0/2125.132.192.1 to 25.132.199.25425.132.199.2552,046
15425.132.200.0/2125.132.200.1 to 25.132.207.25425.132.207.2552,046
15525.132.208.0/2125.132.208.1 to 25.132.215.25425.132.215.2552,046
15625.132.216.0/2125.132.216.1 to 25.132.223.25425.132.223.2552,046
15725.132.224.0/2125.132.224.1 to 25.132.231.25425.132.231.2552,046
15825.132.232.0/2125.132.232.1 to 25.132.239.25425.132.239.2552,046
15925.132.240.0/2125.132.240.1 to 25.132.247.25425.132.247.2552,046
16025.132.248.0/2125.132.248.1 to 25.132.255.25425.132.255.2552,046
16125.133.0.0/2125.133.0.1 to 25.133.7.25425.133.7.2552,046
16225.133.8.0/2125.133.8.1 to 25.133.15.25425.133.15.2552,046
16325.133.16.0/2125.133.16.1 to 25.133.23.25425.133.23.2552,046
16425.133.24.0/2125.133.24.1 to 25.133.31.25425.133.31.2552,046
16525.133.32.0/2125.133.32.1 to 25.133.39.25425.133.39.2552,046
16625.133.40.0/2125.133.40.1 to 25.133.47.25425.133.47.2552,046
16725.133.48.0/2125.133.48.1 to 25.133.55.25425.133.55.2552,046
16825.133.56.0/2125.133.56.1 to 25.133.63.25425.133.63.2552,046
16925.133.64.0/2125.133.64.1 to 25.133.71.25425.133.71.2552,046
17025.133.72.0/2125.133.72.1 to 25.133.79.25425.133.79.2552,046
17125.133.80.0/2125.133.80.1 to 25.133.87.25425.133.87.2552,046
17225.133.88.0/2125.133.88.1 to 25.133.95.25425.133.95.2552,046
17325.133.96.0/2125.133.96.1 to 25.133.103.25425.133.103.2552,046
17425.133.104.0/2125.133.104.1 to 25.133.111.25425.133.111.2552,046
17525.133.112.0/2125.133.112.1 to 25.133.119.25425.133.119.2552,046
17625.133.120.0/2125.133.120.1 to 25.133.127.25425.133.127.2552,046
17725.133.128.0/2125.133.128.1 to 25.133.135.25425.133.135.2552,046
17825.133.136.0/2125.133.136.1 to 25.133.143.25425.133.143.2552,046
17925.133.144.0/2125.133.144.1 to 25.133.151.25425.133.151.2552,046
18025.133.152.0/2125.133.152.1 to 25.133.159.25425.133.159.2552,046
18125.133.160.0/2125.133.160.1 to 25.133.167.25425.133.167.2552,046
18225.133.168.0/2125.133.168.1 to 25.133.175.25425.133.175.2552,046
18325.133.176.0/2125.133.176.1 to 25.133.183.25425.133.183.2552,046
18425.133.184.0/2125.133.184.1 to 25.133.191.25425.133.191.2552,046
18525.133.192.0/2125.133.192.1 to 25.133.199.25425.133.199.2552,046
18625.133.200.0/2125.133.200.1 to 25.133.207.25425.133.207.2552,046
18725.133.208.0/2125.133.208.1 to 25.133.215.25425.133.215.2552,046
18825.133.216.0/2125.133.216.1 to 25.133.223.25425.133.223.2552,046
18925.133.224.0/2125.133.224.1 to 25.133.231.25425.133.231.2552,046
19025.133.232.0/2125.133.232.1 to 25.133.239.25425.133.239.2552,046
19125.133.240.0/2125.133.240.1 to 25.133.247.25425.133.247.2552,046
19225.133.248.0/2125.133.248.1 to 25.133.255.25425.133.255.2552,046
19325.134.0.0/2125.134.0.1 to 25.134.7.25425.134.7.2552,046
19425.134.8.0/2125.134.8.1 to 25.134.15.25425.134.15.2552,046
19525.134.16.0/2125.134.16.1 to 25.134.23.25425.134.23.2552,046
19625.134.24.0/2125.134.24.1 to 25.134.31.25425.134.31.2552,046
19725.134.32.0/2125.134.32.1 to 25.134.39.25425.134.39.2552,046
19825.134.40.0/2125.134.40.1 to 25.134.47.25425.134.47.2552,046
19925.134.48.0/2125.134.48.1 to 25.134.55.25425.134.55.2552,046
20025.134.56.0/2125.134.56.1 to 25.134.63.25425.134.63.2552,046
20125.134.64.0/2125.134.64.1 to 25.134.71.25425.134.71.2552,046
20225.134.72.0/2125.134.72.1 to 25.134.79.25425.134.79.2552,046
20325.134.80.0/2125.134.80.1 to 25.134.87.25425.134.87.2552,046
20425.134.88.0/2125.134.88.1 to 25.134.95.25425.134.95.2552,046
20525.134.96.0/2125.134.96.1 to 25.134.103.25425.134.103.2552,046
20625.134.104.0/2125.134.104.1 to 25.134.111.25425.134.111.2552,046
20725.134.112.0/2125.134.112.1 to 25.134.119.25425.134.119.2552,046
20825.134.120.0/2125.134.120.1 to 25.134.127.25425.134.127.2552,046
20925.134.128.0/2125.134.128.1 to 25.134.135.25425.134.135.2552,046
21025.134.136.0/2125.134.136.1 to 25.134.143.25425.134.143.2552,046
21125.134.144.0/2125.134.144.1 to 25.134.151.25425.134.151.2552,046
21225.134.152.0/2125.134.152.1 to 25.134.159.25425.134.159.2552,046
21325.134.160.0/2125.134.160.1 to 25.134.167.25425.134.167.2552,046
21425.134.168.0/2125.134.168.1 to 25.134.175.25425.134.175.2552,046
21525.134.176.0/2125.134.176.1 to 25.134.183.25425.134.183.2552,046
21625.134.184.0/2125.134.184.1 to 25.134.191.25425.134.191.2552,046
21725.134.192.0/2125.134.192.1 to 25.134.199.25425.134.199.2552,046
21825.134.200.0/2125.134.200.1 to 25.134.207.25425.134.207.2552,046
21925.134.208.0/2125.134.208.1 to 25.134.215.25425.134.215.2552,046
22025.134.216.0/2125.134.216.1 to 25.134.223.25425.134.223.2552,046
22125.134.224.0/2125.134.224.1 to 25.134.231.25425.134.231.2552,046
22225.134.232.0/2125.134.232.1 to 25.134.239.25425.134.239.2552,046
22325.134.240.0/2125.134.240.1 to 25.134.247.25425.134.247.2552,046
22425.134.248.0/2125.134.248.1 to 25.134.255.25425.134.255.2552,046
22525.135.0.0/2125.135.0.1 to 25.135.7.25425.135.7.2552,046
22625.135.8.0/2125.135.8.1 to 25.135.15.25425.135.15.2552,046
22725.135.16.0/2125.135.16.1 to 25.135.23.25425.135.23.2552,046
22825.135.24.0/2125.135.24.1 to 25.135.31.25425.135.31.2552,046
22925.135.32.0/2125.135.32.1 to 25.135.39.25425.135.39.2552,046
23025.135.40.0/2125.135.40.1 to 25.135.47.25425.135.47.2552,046
23125.135.48.0/2125.135.48.1 to 25.135.55.25425.135.55.2552,046
23225.135.56.0/2125.135.56.1 to 25.135.63.25425.135.63.2552,046
23325.135.64.0/2125.135.64.1 to 25.135.71.25425.135.71.2552,046
23425.135.72.0/2125.135.72.1 to 25.135.79.25425.135.79.2552,046
23525.135.80.0/2125.135.80.1 to 25.135.87.25425.135.87.2552,046
23625.135.88.0/2125.135.88.1 to 25.135.95.25425.135.95.2552,046
23725.135.96.0/2125.135.96.1 to 25.135.103.25425.135.103.2552,046
23825.135.104.0/2125.135.104.1 to 25.135.111.25425.135.111.2552,046
23925.135.112.0/2125.135.112.1 to 25.135.119.25425.135.119.2552,046
24025.135.120.0/2125.135.120.1 to 25.135.127.25425.135.127.2552,046
24125.135.128.0/2125.135.128.1 to 25.135.135.25425.135.135.2552,046
24225.135.136.0/2125.135.136.1 to 25.135.143.25425.135.143.2552,046
24325.135.144.0/2125.135.144.1 to 25.135.151.25425.135.151.2552,046
24425.135.152.0/2125.135.152.1 to 25.135.159.25425.135.159.2552,046
24525.135.160.0/2125.135.160.1 to 25.135.167.25425.135.167.2552,046
24625.135.168.0/2125.135.168.1 to 25.135.175.25425.135.175.2552,046
24725.135.176.0/2125.135.176.1 to 25.135.183.25425.135.183.2552,046
24825.135.184.0/2125.135.184.1 to 25.135.191.25425.135.191.2552,046
24925.135.192.0/2125.135.192.1 to 25.135.199.25425.135.199.2552,046
25025.135.200.0/2125.135.200.1 to 25.135.207.25425.135.207.2552,046
25125.135.208.0/2125.135.208.1 to 25.135.215.25425.135.215.2552,046
25225.135.216.0/2125.135.216.1 to 25.135.223.25425.135.223.2552,046
25325.135.224.0/2125.135.224.1 to 25.135.231.25425.135.231.2552,046
25425.135.232.0/2125.135.232.1 to 25.135.239.25425.135.239.2552,046
25525.135.240.0/2125.135.240.1 to 25.135.247.25425.135.247.2552,046
25625.135.248.0/2125.135.248.1 to 25.135.255.25425.135.255.2552,046

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.