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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.

Network25.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
25.0.0.0
Broadcast address
25.255.255.255
First usable
25.0.0.1
Last usable
25.255.255.254
Usable hosts
16,777,214 (16,777,216 less the network and broadcast addresses)
Subnet mask
255.0.0.0
Wildcard mask
0.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/8
Type
Public public
Old class
A (default /8)
As numbers
Hex 19000000 · Integer 419430400 to 436207615
Reverse DNS zone
25.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00011001..00000000.00000000.0000000025.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network00011001..00000000.00000000.0000000025.0.0.0
Broadcast00011001..11111111.11111111.1111111125.255.255.255
Split into smaller subnets/20
/9 (2)/10 (4)/11 (8)/12 (16)/13 (32)/14 (64)/15 (128)/16 (256)/17 (512)/18 (1,024)/19 (2,048)/20 (4,096)

25.0.0.0/8 makes 4,096 subnets of /20; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
125.0.0.0/2025.0.0.1 to 25.0.15.25425.0.15.2554,094
225.0.16.0/2025.0.16.1 to 25.0.31.25425.0.31.2554,094
325.0.32.0/2025.0.32.1 to 25.0.47.25425.0.47.2554,094
425.0.48.0/2025.0.48.1 to 25.0.63.25425.0.63.2554,094
525.0.64.0/2025.0.64.1 to 25.0.79.25425.0.79.2554,094
625.0.80.0/2025.0.80.1 to 25.0.95.25425.0.95.2554,094
725.0.96.0/2025.0.96.1 to 25.0.111.25425.0.111.2554,094
825.0.112.0/2025.0.112.1 to 25.0.127.25425.0.127.2554,094
925.0.128.0/2025.0.128.1 to 25.0.143.25425.0.143.2554,094
1025.0.144.0/2025.0.144.1 to 25.0.159.25425.0.159.2554,094
1125.0.160.0/2025.0.160.1 to 25.0.175.25425.0.175.2554,094
1225.0.176.0/2025.0.176.1 to 25.0.191.25425.0.191.2554,094
1325.0.192.0/2025.0.192.1 to 25.0.207.25425.0.207.2554,094
1425.0.208.0/2025.0.208.1 to 25.0.223.25425.0.223.2554,094
1525.0.224.0/2025.0.224.1 to 25.0.239.25425.0.239.2554,094
1625.0.240.0/2025.0.240.1 to 25.0.255.25425.0.255.2554,094
1725.1.0.0/2025.1.0.1 to 25.1.15.25425.1.15.2554,094
1825.1.16.0/2025.1.16.1 to 25.1.31.25425.1.31.2554,094
1925.1.32.0/2025.1.32.1 to 25.1.47.25425.1.47.2554,094
2025.1.48.0/2025.1.48.1 to 25.1.63.25425.1.63.2554,094
2125.1.64.0/2025.1.64.1 to 25.1.79.25425.1.79.2554,094
2225.1.80.0/2025.1.80.1 to 25.1.95.25425.1.95.2554,094
2325.1.96.0/2025.1.96.1 to 25.1.111.25425.1.111.2554,094
2425.1.112.0/2025.1.112.1 to 25.1.127.25425.1.127.2554,094
2525.1.128.0/2025.1.128.1 to 25.1.143.25425.1.143.2554,094
2625.1.144.0/2025.1.144.1 to 25.1.159.25425.1.159.2554,094
2725.1.160.0/2025.1.160.1 to 25.1.175.25425.1.175.2554,094
2825.1.176.0/2025.1.176.1 to 25.1.191.25425.1.191.2554,094
2925.1.192.0/2025.1.192.1 to 25.1.207.25425.1.207.2554,094
3025.1.208.0/2025.1.208.1 to 25.1.223.25425.1.223.2554,094
3125.1.224.0/2025.1.224.1 to 25.1.239.25425.1.239.2554,094
3225.1.240.0/2025.1.240.1 to 25.1.255.25425.1.255.2554,094
3325.2.0.0/2025.2.0.1 to 25.2.15.25425.2.15.2554,094
3425.2.16.0/2025.2.16.1 to 25.2.31.25425.2.31.2554,094
3525.2.32.0/2025.2.32.1 to 25.2.47.25425.2.47.2554,094
3625.2.48.0/2025.2.48.1 to 25.2.63.25425.2.63.2554,094
3725.2.64.0/2025.2.64.1 to 25.2.79.25425.2.79.2554,094
3825.2.80.0/2025.2.80.1 to 25.2.95.25425.2.95.2554,094
3925.2.96.0/2025.2.96.1 to 25.2.111.25425.2.111.2554,094
4025.2.112.0/2025.2.112.1 to 25.2.127.25425.2.127.2554,094
4125.2.128.0/2025.2.128.1 to 25.2.143.25425.2.143.2554,094
4225.2.144.0/2025.2.144.1 to 25.2.159.25425.2.159.2554,094
4325.2.160.0/2025.2.160.1 to 25.2.175.25425.2.175.2554,094
4425.2.176.0/2025.2.176.1 to 25.2.191.25425.2.191.2554,094
4525.2.192.0/2025.2.192.1 to 25.2.207.25425.2.207.2554,094
4625.2.208.0/2025.2.208.1 to 25.2.223.25425.2.223.2554,094
4725.2.224.0/2025.2.224.1 to 25.2.239.25425.2.239.2554,094
4825.2.240.0/2025.2.240.1 to 25.2.255.25425.2.255.2554,094
4925.3.0.0/2025.3.0.1 to 25.3.15.25425.3.15.2554,094
5025.3.16.0/2025.3.16.1 to 25.3.31.25425.3.31.2554,094
5125.3.32.0/2025.3.32.1 to 25.3.47.25425.3.47.2554,094
5225.3.48.0/2025.3.48.1 to 25.3.63.25425.3.63.2554,094
5325.3.64.0/2025.3.64.1 to 25.3.79.25425.3.79.2554,094
5425.3.80.0/2025.3.80.1 to 25.3.95.25425.3.95.2554,094
5525.3.96.0/2025.3.96.1 to 25.3.111.25425.3.111.2554,094
5625.3.112.0/2025.3.112.1 to 25.3.127.25425.3.127.2554,094
5725.3.128.0/2025.3.128.1 to 25.3.143.25425.3.143.2554,094
5825.3.144.0/2025.3.144.1 to 25.3.159.25425.3.159.2554,094
5925.3.160.0/2025.3.160.1 to 25.3.175.25425.3.175.2554,094
6025.3.176.0/2025.3.176.1 to 25.3.191.25425.3.191.2554,094
6125.3.192.0/2025.3.192.1 to 25.3.207.25425.3.207.2554,094
6225.3.208.0/2025.3.208.1 to 25.3.223.25425.3.223.2554,094
6325.3.224.0/2025.3.224.1 to 25.3.239.25425.3.239.2554,094
6425.3.240.0/2025.3.240.1 to 25.3.255.25425.3.255.2554,094
6525.4.0.0/2025.4.0.1 to 25.4.15.25425.4.15.2554,094
6625.4.16.0/2025.4.16.1 to 25.4.31.25425.4.31.2554,094
6725.4.32.0/2025.4.32.1 to 25.4.47.25425.4.47.2554,094
6825.4.48.0/2025.4.48.1 to 25.4.63.25425.4.63.2554,094
6925.4.64.0/2025.4.64.1 to 25.4.79.25425.4.79.2554,094
7025.4.80.0/2025.4.80.1 to 25.4.95.25425.4.95.2554,094
7125.4.96.0/2025.4.96.1 to 25.4.111.25425.4.111.2554,094
7225.4.112.0/2025.4.112.1 to 25.4.127.25425.4.127.2554,094
7325.4.128.0/2025.4.128.1 to 25.4.143.25425.4.143.2554,094
7425.4.144.0/2025.4.144.1 to 25.4.159.25425.4.159.2554,094
7525.4.160.0/2025.4.160.1 to 25.4.175.25425.4.175.2554,094
7625.4.176.0/2025.4.176.1 to 25.4.191.25425.4.191.2554,094
7725.4.192.0/2025.4.192.1 to 25.4.207.25425.4.207.2554,094
7825.4.208.0/2025.4.208.1 to 25.4.223.25425.4.223.2554,094
7925.4.224.0/2025.4.224.1 to 25.4.239.25425.4.239.2554,094
8025.4.240.0/2025.4.240.1 to 25.4.255.25425.4.255.2554,094
8125.5.0.0/2025.5.0.1 to 25.5.15.25425.5.15.2554,094
8225.5.16.0/2025.5.16.1 to 25.5.31.25425.5.31.2554,094
8325.5.32.0/2025.5.32.1 to 25.5.47.25425.5.47.2554,094
8425.5.48.0/2025.5.48.1 to 25.5.63.25425.5.63.2554,094
8525.5.64.0/2025.5.64.1 to 25.5.79.25425.5.79.2554,094
8625.5.80.0/2025.5.80.1 to 25.5.95.25425.5.95.2554,094
8725.5.96.0/2025.5.96.1 to 25.5.111.25425.5.111.2554,094
8825.5.112.0/2025.5.112.1 to 25.5.127.25425.5.127.2554,094
8925.5.128.0/2025.5.128.1 to 25.5.143.25425.5.143.2554,094
9025.5.144.0/2025.5.144.1 to 25.5.159.25425.5.159.2554,094
9125.5.160.0/2025.5.160.1 to 25.5.175.25425.5.175.2554,094
9225.5.176.0/2025.5.176.1 to 25.5.191.25425.5.191.2554,094
9325.5.192.0/2025.5.192.1 to 25.5.207.25425.5.207.2554,094
9425.5.208.0/2025.5.208.1 to 25.5.223.25425.5.223.2554,094
9525.5.224.0/2025.5.224.1 to 25.5.239.25425.5.239.2554,094
9625.5.240.0/2025.5.240.1 to 25.5.255.25425.5.255.2554,094
9725.6.0.0/2025.6.0.1 to 25.6.15.25425.6.15.2554,094
9825.6.16.0/2025.6.16.1 to 25.6.31.25425.6.31.2554,094
9925.6.32.0/2025.6.32.1 to 25.6.47.25425.6.47.2554,094
10025.6.48.0/2025.6.48.1 to 25.6.63.25425.6.63.2554,094
10125.6.64.0/2025.6.64.1 to 25.6.79.25425.6.79.2554,094
10225.6.80.0/2025.6.80.1 to 25.6.95.25425.6.95.2554,094
10325.6.96.0/2025.6.96.1 to 25.6.111.25425.6.111.2554,094
10425.6.112.0/2025.6.112.1 to 25.6.127.25425.6.127.2554,094
10525.6.128.0/2025.6.128.1 to 25.6.143.25425.6.143.2554,094
10625.6.144.0/2025.6.144.1 to 25.6.159.25425.6.159.2554,094
10725.6.160.0/2025.6.160.1 to 25.6.175.25425.6.175.2554,094
10825.6.176.0/2025.6.176.1 to 25.6.191.25425.6.191.2554,094
10925.6.192.0/2025.6.192.1 to 25.6.207.25425.6.207.2554,094
11025.6.208.0/2025.6.208.1 to 25.6.223.25425.6.223.2554,094
11125.6.224.0/2025.6.224.1 to 25.6.239.25425.6.239.2554,094
11225.6.240.0/2025.6.240.1 to 25.6.255.25425.6.255.2554,094
11325.7.0.0/2025.7.0.1 to 25.7.15.25425.7.15.2554,094
11425.7.16.0/2025.7.16.1 to 25.7.31.25425.7.31.2554,094
11525.7.32.0/2025.7.32.1 to 25.7.47.25425.7.47.2554,094
11625.7.48.0/2025.7.48.1 to 25.7.63.25425.7.63.2554,094
11725.7.64.0/2025.7.64.1 to 25.7.79.25425.7.79.2554,094
11825.7.80.0/2025.7.80.1 to 25.7.95.25425.7.95.2554,094
11925.7.96.0/2025.7.96.1 to 25.7.111.25425.7.111.2554,094
12025.7.112.0/2025.7.112.1 to 25.7.127.25425.7.127.2554,094
12125.7.128.0/2025.7.128.1 to 25.7.143.25425.7.143.2554,094
12225.7.144.0/2025.7.144.1 to 25.7.159.25425.7.159.2554,094
12325.7.160.0/2025.7.160.1 to 25.7.175.25425.7.175.2554,094
12425.7.176.0/2025.7.176.1 to 25.7.191.25425.7.191.2554,094
12525.7.192.0/2025.7.192.1 to 25.7.207.25425.7.207.2554,094
12625.7.208.0/2025.7.208.1 to 25.7.223.25425.7.223.2554,094
12725.7.224.0/2025.7.224.1 to 25.7.239.25425.7.239.2554,094
12825.7.240.0/2025.7.240.1 to 25.7.255.25425.7.255.2554,094
12925.8.0.0/2025.8.0.1 to 25.8.15.25425.8.15.2554,094
13025.8.16.0/2025.8.16.1 to 25.8.31.25425.8.31.2554,094
13125.8.32.0/2025.8.32.1 to 25.8.47.25425.8.47.2554,094
13225.8.48.0/2025.8.48.1 to 25.8.63.25425.8.63.2554,094
13325.8.64.0/2025.8.64.1 to 25.8.79.25425.8.79.2554,094
13425.8.80.0/2025.8.80.1 to 25.8.95.25425.8.95.2554,094
13525.8.96.0/2025.8.96.1 to 25.8.111.25425.8.111.2554,094
13625.8.112.0/2025.8.112.1 to 25.8.127.25425.8.127.2554,094
13725.8.128.0/2025.8.128.1 to 25.8.143.25425.8.143.2554,094
13825.8.144.0/2025.8.144.1 to 25.8.159.25425.8.159.2554,094
13925.8.160.0/2025.8.160.1 to 25.8.175.25425.8.175.2554,094
14025.8.176.0/2025.8.176.1 to 25.8.191.25425.8.191.2554,094
14125.8.192.0/2025.8.192.1 to 25.8.207.25425.8.207.2554,094
14225.8.208.0/2025.8.208.1 to 25.8.223.25425.8.223.2554,094
14325.8.224.0/2025.8.224.1 to 25.8.239.25425.8.239.2554,094
14425.8.240.0/2025.8.240.1 to 25.8.255.25425.8.255.2554,094
14525.9.0.0/2025.9.0.1 to 25.9.15.25425.9.15.2554,094
14625.9.16.0/2025.9.16.1 to 25.9.31.25425.9.31.2554,094
14725.9.32.0/2025.9.32.1 to 25.9.47.25425.9.47.2554,094
14825.9.48.0/2025.9.48.1 to 25.9.63.25425.9.63.2554,094
14925.9.64.0/2025.9.64.1 to 25.9.79.25425.9.79.2554,094
15025.9.80.0/2025.9.80.1 to 25.9.95.25425.9.95.2554,094
15125.9.96.0/2025.9.96.1 to 25.9.111.25425.9.111.2554,094
15225.9.112.0/2025.9.112.1 to 25.9.127.25425.9.127.2554,094
15325.9.128.0/2025.9.128.1 to 25.9.143.25425.9.143.2554,094
15425.9.144.0/2025.9.144.1 to 25.9.159.25425.9.159.2554,094
15525.9.160.0/2025.9.160.1 to 25.9.175.25425.9.175.2554,094
15625.9.176.0/2025.9.176.1 to 25.9.191.25425.9.191.2554,094
15725.9.192.0/2025.9.192.1 to 25.9.207.25425.9.207.2554,094
15825.9.208.0/2025.9.208.1 to 25.9.223.25425.9.223.2554,094
15925.9.224.0/2025.9.224.1 to 25.9.239.25425.9.239.2554,094
16025.9.240.0/2025.9.240.1 to 25.9.255.25425.9.255.2554,094
16125.10.0.0/2025.10.0.1 to 25.10.15.25425.10.15.2554,094
16225.10.16.0/2025.10.16.1 to 25.10.31.25425.10.31.2554,094
16325.10.32.0/2025.10.32.1 to 25.10.47.25425.10.47.2554,094
16425.10.48.0/2025.10.48.1 to 25.10.63.25425.10.63.2554,094
16525.10.64.0/2025.10.64.1 to 25.10.79.25425.10.79.2554,094
16625.10.80.0/2025.10.80.1 to 25.10.95.25425.10.95.2554,094
16725.10.96.0/2025.10.96.1 to 25.10.111.25425.10.111.2554,094
16825.10.112.0/2025.10.112.1 to 25.10.127.25425.10.127.2554,094
16925.10.128.0/2025.10.128.1 to 25.10.143.25425.10.143.2554,094
17025.10.144.0/2025.10.144.1 to 25.10.159.25425.10.159.2554,094
17125.10.160.0/2025.10.160.1 to 25.10.175.25425.10.175.2554,094
17225.10.176.0/2025.10.176.1 to 25.10.191.25425.10.191.2554,094
17325.10.192.0/2025.10.192.1 to 25.10.207.25425.10.207.2554,094
17425.10.208.0/2025.10.208.1 to 25.10.223.25425.10.223.2554,094
17525.10.224.0/2025.10.224.1 to 25.10.239.25425.10.239.2554,094
17625.10.240.0/2025.10.240.1 to 25.10.255.25425.10.255.2554,094
17725.11.0.0/2025.11.0.1 to 25.11.15.25425.11.15.2554,094
17825.11.16.0/2025.11.16.1 to 25.11.31.25425.11.31.2554,094
17925.11.32.0/2025.11.32.1 to 25.11.47.25425.11.47.2554,094
18025.11.48.0/2025.11.48.1 to 25.11.63.25425.11.63.2554,094
18125.11.64.0/2025.11.64.1 to 25.11.79.25425.11.79.2554,094
18225.11.80.0/2025.11.80.1 to 25.11.95.25425.11.95.2554,094
18325.11.96.0/2025.11.96.1 to 25.11.111.25425.11.111.2554,094
18425.11.112.0/2025.11.112.1 to 25.11.127.25425.11.127.2554,094
18525.11.128.0/2025.11.128.1 to 25.11.143.25425.11.143.2554,094
18625.11.144.0/2025.11.144.1 to 25.11.159.25425.11.159.2554,094
18725.11.160.0/2025.11.160.1 to 25.11.175.25425.11.175.2554,094
18825.11.176.0/2025.11.176.1 to 25.11.191.25425.11.191.2554,094
18925.11.192.0/2025.11.192.1 to 25.11.207.25425.11.207.2554,094
19025.11.208.0/2025.11.208.1 to 25.11.223.25425.11.223.2554,094
19125.11.224.0/2025.11.224.1 to 25.11.239.25425.11.239.2554,094
19225.11.240.0/2025.11.240.1 to 25.11.255.25425.11.255.2554,094
19325.12.0.0/2025.12.0.1 to 25.12.15.25425.12.15.2554,094
19425.12.16.0/2025.12.16.1 to 25.12.31.25425.12.31.2554,094
19525.12.32.0/2025.12.32.1 to 25.12.47.25425.12.47.2554,094
19625.12.48.0/2025.12.48.1 to 25.12.63.25425.12.63.2554,094
19725.12.64.0/2025.12.64.1 to 25.12.79.25425.12.79.2554,094
19825.12.80.0/2025.12.80.1 to 25.12.95.25425.12.95.2554,094
19925.12.96.0/2025.12.96.1 to 25.12.111.25425.12.111.2554,094
20025.12.112.0/2025.12.112.1 to 25.12.127.25425.12.127.2554,094
20125.12.128.0/2025.12.128.1 to 25.12.143.25425.12.143.2554,094
20225.12.144.0/2025.12.144.1 to 25.12.159.25425.12.159.2554,094
20325.12.160.0/2025.12.160.1 to 25.12.175.25425.12.175.2554,094
20425.12.176.0/2025.12.176.1 to 25.12.191.25425.12.191.2554,094
20525.12.192.0/2025.12.192.1 to 25.12.207.25425.12.207.2554,094
20625.12.208.0/2025.12.208.1 to 25.12.223.25425.12.223.2554,094
20725.12.224.0/2025.12.224.1 to 25.12.239.25425.12.239.2554,094
20825.12.240.0/2025.12.240.1 to 25.12.255.25425.12.255.2554,094
20925.13.0.0/2025.13.0.1 to 25.13.15.25425.13.15.2554,094
21025.13.16.0/2025.13.16.1 to 25.13.31.25425.13.31.2554,094
21125.13.32.0/2025.13.32.1 to 25.13.47.25425.13.47.2554,094
21225.13.48.0/2025.13.48.1 to 25.13.63.25425.13.63.2554,094
21325.13.64.0/2025.13.64.1 to 25.13.79.25425.13.79.2554,094
21425.13.80.0/2025.13.80.1 to 25.13.95.25425.13.95.2554,094
21525.13.96.0/2025.13.96.1 to 25.13.111.25425.13.111.2554,094
21625.13.112.0/2025.13.112.1 to 25.13.127.25425.13.127.2554,094
21725.13.128.0/2025.13.128.1 to 25.13.143.25425.13.143.2554,094
21825.13.144.0/2025.13.144.1 to 25.13.159.25425.13.159.2554,094
21925.13.160.0/2025.13.160.1 to 25.13.175.25425.13.175.2554,094
22025.13.176.0/2025.13.176.1 to 25.13.191.25425.13.191.2554,094
22125.13.192.0/2025.13.192.1 to 25.13.207.25425.13.207.2554,094
22225.13.208.0/2025.13.208.1 to 25.13.223.25425.13.223.2554,094
22325.13.224.0/2025.13.224.1 to 25.13.239.25425.13.239.2554,094
22425.13.240.0/2025.13.240.1 to 25.13.255.25425.13.255.2554,094
22525.14.0.0/2025.14.0.1 to 25.14.15.25425.14.15.2554,094
22625.14.16.0/2025.14.16.1 to 25.14.31.25425.14.31.2554,094
22725.14.32.0/2025.14.32.1 to 25.14.47.25425.14.47.2554,094
22825.14.48.0/2025.14.48.1 to 25.14.63.25425.14.63.2554,094
22925.14.64.0/2025.14.64.1 to 25.14.79.25425.14.79.2554,094
23025.14.80.0/2025.14.80.1 to 25.14.95.25425.14.95.2554,094
23125.14.96.0/2025.14.96.1 to 25.14.111.25425.14.111.2554,094
23225.14.112.0/2025.14.112.1 to 25.14.127.25425.14.127.2554,094
23325.14.128.0/2025.14.128.1 to 25.14.143.25425.14.143.2554,094
23425.14.144.0/2025.14.144.1 to 25.14.159.25425.14.159.2554,094
23525.14.160.0/2025.14.160.1 to 25.14.175.25425.14.175.2554,094
23625.14.176.0/2025.14.176.1 to 25.14.191.25425.14.191.2554,094
23725.14.192.0/2025.14.192.1 to 25.14.207.25425.14.207.2554,094
23825.14.208.0/2025.14.208.1 to 25.14.223.25425.14.223.2554,094
23925.14.224.0/2025.14.224.1 to 25.14.239.25425.14.239.2554,094
24025.14.240.0/2025.14.240.1 to 25.14.255.25425.14.255.2554,094
24125.15.0.0/2025.15.0.1 to 25.15.15.25425.15.15.2554,094
24225.15.16.0/2025.15.16.1 to 25.15.31.25425.15.31.2554,094
24325.15.32.0/2025.15.32.1 to 25.15.47.25425.15.47.2554,094
24425.15.48.0/2025.15.48.1 to 25.15.63.25425.15.63.2554,094
24525.15.64.0/2025.15.64.1 to 25.15.79.25425.15.79.2554,094
24625.15.80.0/2025.15.80.1 to 25.15.95.25425.15.95.2554,094
24725.15.96.0/2025.15.96.1 to 25.15.111.25425.15.111.2554,094
24825.15.112.0/2025.15.112.1 to 25.15.127.25425.15.127.2554,094
24925.15.128.0/2025.15.128.1 to 25.15.143.25425.15.143.2554,094
25025.15.144.0/2025.15.144.1 to 25.15.159.25425.15.159.2554,094
25125.15.160.0/2025.15.160.1 to 25.15.175.25425.15.175.2554,094
25225.15.176.0/2025.15.176.1 to 25.15.191.25425.15.191.2554,094
25325.15.192.0/2025.15.192.1 to 25.15.207.25425.15.207.2554,094
25425.15.208.0/2025.15.208.1 to 25.15.223.25425.15.223.2554,094
25525.15.224.0/2025.15.224.1 to 25.15.239.25425.15.239.2554,094
25625.15.240.0/2025.15.240.1 to 25.15.255.25425.15.255.2554,094

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.