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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.

Network66.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
66.0.0.0
Broadcast address
66.255.255.255
First usable
66.0.0.1
Last usable
66.255.255.254
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 42000000 · Integer 1107296256 to 1124073471
Reverse DNS zone
66.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01000010..00000000.00000000.0000000066.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network01000010..00000000.00000000.0000000066.0.0.0
Broadcast01000010..11111111.11111111.1111111166.255.255.255
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)

66.0.0.0/8 makes 4,096 subnets of /20; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
166.0.0.0/2066.0.0.1 to 66.0.15.25466.0.15.2554,094
266.0.16.0/2066.0.16.1 to 66.0.31.25466.0.31.2554,094
366.0.32.0/2066.0.32.1 to 66.0.47.25466.0.47.2554,094
466.0.48.0/2066.0.48.1 to 66.0.63.25466.0.63.2554,094
566.0.64.0/2066.0.64.1 to 66.0.79.25466.0.79.2554,094
666.0.80.0/2066.0.80.1 to 66.0.95.25466.0.95.2554,094
766.0.96.0/2066.0.96.1 to 66.0.111.25466.0.111.2554,094
866.0.112.0/2066.0.112.1 to 66.0.127.25466.0.127.2554,094
966.0.128.0/2066.0.128.1 to 66.0.143.25466.0.143.2554,094
1066.0.144.0/2066.0.144.1 to 66.0.159.25466.0.159.2554,094
1166.0.160.0/2066.0.160.1 to 66.0.175.25466.0.175.2554,094
1266.0.176.0/2066.0.176.1 to 66.0.191.25466.0.191.2554,094
1366.0.192.0/2066.0.192.1 to 66.0.207.25466.0.207.2554,094
1466.0.208.0/2066.0.208.1 to 66.0.223.25466.0.223.2554,094
1566.0.224.0/2066.0.224.1 to 66.0.239.25466.0.239.2554,094
1666.0.240.0/2066.0.240.1 to 66.0.255.25466.0.255.2554,094
1766.1.0.0/2066.1.0.1 to 66.1.15.25466.1.15.2554,094
1866.1.16.0/2066.1.16.1 to 66.1.31.25466.1.31.2554,094
1966.1.32.0/2066.1.32.1 to 66.1.47.25466.1.47.2554,094
2066.1.48.0/2066.1.48.1 to 66.1.63.25466.1.63.2554,094
2166.1.64.0/2066.1.64.1 to 66.1.79.25466.1.79.2554,094
2266.1.80.0/2066.1.80.1 to 66.1.95.25466.1.95.2554,094
2366.1.96.0/2066.1.96.1 to 66.1.111.25466.1.111.2554,094
2466.1.112.0/2066.1.112.1 to 66.1.127.25466.1.127.2554,094
2566.1.128.0/2066.1.128.1 to 66.1.143.25466.1.143.2554,094
2666.1.144.0/2066.1.144.1 to 66.1.159.25466.1.159.2554,094
2766.1.160.0/2066.1.160.1 to 66.1.175.25466.1.175.2554,094
2866.1.176.0/2066.1.176.1 to 66.1.191.25466.1.191.2554,094
2966.1.192.0/2066.1.192.1 to 66.1.207.25466.1.207.2554,094
3066.1.208.0/2066.1.208.1 to 66.1.223.25466.1.223.2554,094
3166.1.224.0/2066.1.224.1 to 66.1.239.25466.1.239.2554,094
3266.1.240.0/2066.1.240.1 to 66.1.255.25466.1.255.2554,094
3366.2.0.0/2066.2.0.1 to 66.2.15.25466.2.15.2554,094
3466.2.16.0/2066.2.16.1 to 66.2.31.25466.2.31.2554,094
3566.2.32.0/2066.2.32.1 to 66.2.47.25466.2.47.2554,094
3666.2.48.0/2066.2.48.1 to 66.2.63.25466.2.63.2554,094
3766.2.64.0/2066.2.64.1 to 66.2.79.25466.2.79.2554,094
3866.2.80.0/2066.2.80.1 to 66.2.95.25466.2.95.2554,094
3966.2.96.0/2066.2.96.1 to 66.2.111.25466.2.111.2554,094
4066.2.112.0/2066.2.112.1 to 66.2.127.25466.2.127.2554,094
4166.2.128.0/2066.2.128.1 to 66.2.143.25466.2.143.2554,094
4266.2.144.0/2066.2.144.1 to 66.2.159.25466.2.159.2554,094
4366.2.160.0/2066.2.160.1 to 66.2.175.25466.2.175.2554,094
4466.2.176.0/2066.2.176.1 to 66.2.191.25466.2.191.2554,094
4566.2.192.0/2066.2.192.1 to 66.2.207.25466.2.207.2554,094
4666.2.208.0/2066.2.208.1 to 66.2.223.25466.2.223.2554,094
4766.2.224.0/2066.2.224.1 to 66.2.239.25466.2.239.2554,094
4866.2.240.0/2066.2.240.1 to 66.2.255.25466.2.255.2554,094
4966.3.0.0/2066.3.0.1 to 66.3.15.25466.3.15.2554,094
5066.3.16.0/2066.3.16.1 to 66.3.31.25466.3.31.2554,094
5166.3.32.0/2066.3.32.1 to 66.3.47.25466.3.47.2554,094
5266.3.48.0/2066.3.48.1 to 66.3.63.25466.3.63.2554,094
5366.3.64.0/2066.3.64.1 to 66.3.79.25466.3.79.2554,094
5466.3.80.0/2066.3.80.1 to 66.3.95.25466.3.95.2554,094
5566.3.96.0/2066.3.96.1 to 66.3.111.25466.3.111.2554,094
5666.3.112.0/2066.3.112.1 to 66.3.127.25466.3.127.2554,094
5766.3.128.0/2066.3.128.1 to 66.3.143.25466.3.143.2554,094
5866.3.144.0/2066.3.144.1 to 66.3.159.25466.3.159.2554,094
5966.3.160.0/2066.3.160.1 to 66.3.175.25466.3.175.2554,094
6066.3.176.0/2066.3.176.1 to 66.3.191.25466.3.191.2554,094
6166.3.192.0/2066.3.192.1 to 66.3.207.25466.3.207.2554,094
6266.3.208.0/2066.3.208.1 to 66.3.223.25466.3.223.2554,094
6366.3.224.0/2066.3.224.1 to 66.3.239.25466.3.239.2554,094
6466.3.240.0/2066.3.240.1 to 66.3.255.25466.3.255.2554,094
6566.4.0.0/2066.4.0.1 to 66.4.15.25466.4.15.2554,094
6666.4.16.0/2066.4.16.1 to 66.4.31.25466.4.31.2554,094
6766.4.32.0/2066.4.32.1 to 66.4.47.25466.4.47.2554,094
6866.4.48.0/2066.4.48.1 to 66.4.63.25466.4.63.2554,094
6966.4.64.0/2066.4.64.1 to 66.4.79.25466.4.79.2554,094
7066.4.80.0/2066.4.80.1 to 66.4.95.25466.4.95.2554,094
7166.4.96.0/2066.4.96.1 to 66.4.111.25466.4.111.2554,094
7266.4.112.0/2066.4.112.1 to 66.4.127.25466.4.127.2554,094
7366.4.128.0/2066.4.128.1 to 66.4.143.25466.4.143.2554,094
7466.4.144.0/2066.4.144.1 to 66.4.159.25466.4.159.2554,094
7566.4.160.0/2066.4.160.1 to 66.4.175.25466.4.175.2554,094
7666.4.176.0/2066.4.176.1 to 66.4.191.25466.4.191.2554,094
7766.4.192.0/2066.4.192.1 to 66.4.207.25466.4.207.2554,094
7866.4.208.0/2066.4.208.1 to 66.4.223.25466.4.223.2554,094
7966.4.224.0/2066.4.224.1 to 66.4.239.25466.4.239.2554,094
8066.4.240.0/2066.4.240.1 to 66.4.255.25466.4.255.2554,094
8166.5.0.0/2066.5.0.1 to 66.5.15.25466.5.15.2554,094
8266.5.16.0/2066.5.16.1 to 66.5.31.25466.5.31.2554,094
8366.5.32.0/2066.5.32.1 to 66.5.47.25466.5.47.2554,094
8466.5.48.0/2066.5.48.1 to 66.5.63.25466.5.63.2554,094
8566.5.64.0/2066.5.64.1 to 66.5.79.25466.5.79.2554,094
8666.5.80.0/2066.5.80.1 to 66.5.95.25466.5.95.2554,094
8766.5.96.0/2066.5.96.1 to 66.5.111.25466.5.111.2554,094
8866.5.112.0/2066.5.112.1 to 66.5.127.25466.5.127.2554,094
8966.5.128.0/2066.5.128.1 to 66.5.143.25466.5.143.2554,094
9066.5.144.0/2066.5.144.1 to 66.5.159.25466.5.159.2554,094
9166.5.160.0/2066.5.160.1 to 66.5.175.25466.5.175.2554,094
9266.5.176.0/2066.5.176.1 to 66.5.191.25466.5.191.2554,094
9366.5.192.0/2066.5.192.1 to 66.5.207.25466.5.207.2554,094
9466.5.208.0/2066.5.208.1 to 66.5.223.25466.5.223.2554,094
9566.5.224.0/2066.5.224.1 to 66.5.239.25466.5.239.2554,094
9666.5.240.0/2066.5.240.1 to 66.5.255.25466.5.255.2554,094
9766.6.0.0/2066.6.0.1 to 66.6.15.25466.6.15.2554,094
9866.6.16.0/2066.6.16.1 to 66.6.31.25466.6.31.2554,094
9966.6.32.0/2066.6.32.1 to 66.6.47.25466.6.47.2554,094
10066.6.48.0/2066.6.48.1 to 66.6.63.25466.6.63.2554,094
10166.6.64.0/2066.6.64.1 to 66.6.79.25466.6.79.2554,094
10266.6.80.0/2066.6.80.1 to 66.6.95.25466.6.95.2554,094
10366.6.96.0/2066.6.96.1 to 66.6.111.25466.6.111.2554,094
10466.6.112.0/2066.6.112.1 to 66.6.127.25466.6.127.2554,094
10566.6.128.0/2066.6.128.1 to 66.6.143.25466.6.143.2554,094
10666.6.144.0/2066.6.144.1 to 66.6.159.25466.6.159.2554,094
10766.6.160.0/2066.6.160.1 to 66.6.175.25466.6.175.2554,094
10866.6.176.0/2066.6.176.1 to 66.6.191.25466.6.191.2554,094
10966.6.192.0/2066.6.192.1 to 66.6.207.25466.6.207.2554,094
11066.6.208.0/2066.6.208.1 to 66.6.223.25466.6.223.2554,094
11166.6.224.0/2066.6.224.1 to 66.6.239.25466.6.239.2554,094
11266.6.240.0/2066.6.240.1 to 66.6.255.25466.6.255.2554,094
11366.7.0.0/2066.7.0.1 to 66.7.15.25466.7.15.2554,094
11466.7.16.0/2066.7.16.1 to 66.7.31.25466.7.31.2554,094
11566.7.32.0/2066.7.32.1 to 66.7.47.25466.7.47.2554,094
11666.7.48.0/2066.7.48.1 to 66.7.63.25466.7.63.2554,094
11766.7.64.0/2066.7.64.1 to 66.7.79.25466.7.79.2554,094
11866.7.80.0/2066.7.80.1 to 66.7.95.25466.7.95.2554,094
11966.7.96.0/2066.7.96.1 to 66.7.111.25466.7.111.2554,094
12066.7.112.0/2066.7.112.1 to 66.7.127.25466.7.127.2554,094
12166.7.128.0/2066.7.128.1 to 66.7.143.25466.7.143.2554,094
12266.7.144.0/2066.7.144.1 to 66.7.159.25466.7.159.2554,094
12366.7.160.0/2066.7.160.1 to 66.7.175.25466.7.175.2554,094
12466.7.176.0/2066.7.176.1 to 66.7.191.25466.7.191.2554,094
12566.7.192.0/2066.7.192.1 to 66.7.207.25466.7.207.2554,094
12666.7.208.0/2066.7.208.1 to 66.7.223.25466.7.223.2554,094
12766.7.224.0/2066.7.224.1 to 66.7.239.25466.7.239.2554,094
12866.7.240.0/2066.7.240.1 to 66.7.255.25466.7.255.2554,094
12966.8.0.0/2066.8.0.1 to 66.8.15.25466.8.15.2554,094
13066.8.16.0/2066.8.16.1 to 66.8.31.25466.8.31.2554,094
13166.8.32.0/2066.8.32.1 to 66.8.47.25466.8.47.2554,094
13266.8.48.0/2066.8.48.1 to 66.8.63.25466.8.63.2554,094
13366.8.64.0/2066.8.64.1 to 66.8.79.25466.8.79.2554,094
13466.8.80.0/2066.8.80.1 to 66.8.95.25466.8.95.2554,094
13566.8.96.0/2066.8.96.1 to 66.8.111.25466.8.111.2554,094
13666.8.112.0/2066.8.112.1 to 66.8.127.25466.8.127.2554,094
13766.8.128.0/2066.8.128.1 to 66.8.143.25466.8.143.2554,094
13866.8.144.0/2066.8.144.1 to 66.8.159.25466.8.159.2554,094
13966.8.160.0/2066.8.160.1 to 66.8.175.25466.8.175.2554,094
14066.8.176.0/2066.8.176.1 to 66.8.191.25466.8.191.2554,094
14166.8.192.0/2066.8.192.1 to 66.8.207.25466.8.207.2554,094
14266.8.208.0/2066.8.208.1 to 66.8.223.25466.8.223.2554,094
14366.8.224.0/2066.8.224.1 to 66.8.239.25466.8.239.2554,094
14466.8.240.0/2066.8.240.1 to 66.8.255.25466.8.255.2554,094
14566.9.0.0/2066.9.0.1 to 66.9.15.25466.9.15.2554,094
14666.9.16.0/2066.9.16.1 to 66.9.31.25466.9.31.2554,094
14766.9.32.0/2066.9.32.1 to 66.9.47.25466.9.47.2554,094
14866.9.48.0/2066.9.48.1 to 66.9.63.25466.9.63.2554,094
14966.9.64.0/2066.9.64.1 to 66.9.79.25466.9.79.2554,094
15066.9.80.0/2066.9.80.1 to 66.9.95.25466.9.95.2554,094
15166.9.96.0/2066.9.96.1 to 66.9.111.25466.9.111.2554,094
15266.9.112.0/2066.9.112.1 to 66.9.127.25466.9.127.2554,094
15366.9.128.0/2066.9.128.1 to 66.9.143.25466.9.143.2554,094
15466.9.144.0/2066.9.144.1 to 66.9.159.25466.9.159.2554,094
15566.9.160.0/2066.9.160.1 to 66.9.175.25466.9.175.2554,094
15666.9.176.0/2066.9.176.1 to 66.9.191.25466.9.191.2554,094
15766.9.192.0/2066.9.192.1 to 66.9.207.25466.9.207.2554,094
15866.9.208.0/2066.9.208.1 to 66.9.223.25466.9.223.2554,094
15966.9.224.0/2066.9.224.1 to 66.9.239.25466.9.239.2554,094
16066.9.240.0/2066.9.240.1 to 66.9.255.25466.9.255.2554,094
16166.10.0.0/2066.10.0.1 to 66.10.15.25466.10.15.2554,094
16266.10.16.0/2066.10.16.1 to 66.10.31.25466.10.31.2554,094
16366.10.32.0/2066.10.32.1 to 66.10.47.25466.10.47.2554,094
16466.10.48.0/2066.10.48.1 to 66.10.63.25466.10.63.2554,094
16566.10.64.0/2066.10.64.1 to 66.10.79.25466.10.79.2554,094
16666.10.80.0/2066.10.80.1 to 66.10.95.25466.10.95.2554,094
16766.10.96.0/2066.10.96.1 to 66.10.111.25466.10.111.2554,094
16866.10.112.0/2066.10.112.1 to 66.10.127.25466.10.127.2554,094
16966.10.128.0/2066.10.128.1 to 66.10.143.25466.10.143.2554,094
17066.10.144.0/2066.10.144.1 to 66.10.159.25466.10.159.2554,094
17166.10.160.0/2066.10.160.1 to 66.10.175.25466.10.175.2554,094
17266.10.176.0/2066.10.176.1 to 66.10.191.25466.10.191.2554,094
17366.10.192.0/2066.10.192.1 to 66.10.207.25466.10.207.2554,094
17466.10.208.0/2066.10.208.1 to 66.10.223.25466.10.223.2554,094
17566.10.224.0/2066.10.224.1 to 66.10.239.25466.10.239.2554,094
17666.10.240.0/2066.10.240.1 to 66.10.255.25466.10.255.2554,094
17766.11.0.0/2066.11.0.1 to 66.11.15.25466.11.15.2554,094
17866.11.16.0/2066.11.16.1 to 66.11.31.25466.11.31.2554,094
17966.11.32.0/2066.11.32.1 to 66.11.47.25466.11.47.2554,094
18066.11.48.0/2066.11.48.1 to 66.11.63.25466.11.63.2554,094
18166.11.64.0/2066.11.64.1 to 66.11.79.25466.11.79.2554,094
18266.11.80.0/2066.11.80.1 to 66.11.95.25466.11.95.2554,094
18366.11.96.0/2066.11.96.1 to 66.11.111.25466.11.111.2554,094
18466.11.112.0/2066.11.112.1 to 66.11.127.25466.11.127.2554,094
18566.11.128.0/2066.11.128.1 to 66.11.143.25466.11.143.2554,094
18666.11.144.0/2066.11.144.1 to 66.11.159.25466.11.159.2554,094
18766.11.160.0/2066.11.160.1 to 66.11.175.25466.11.175.2554,094
18866.11.176.0/2066.11.176.1 to 66.11.191.25466.11.191.2554,094
18966.11.192.0/2066.11.192.1 to 66.11.207.25466.11.207.2554,094
19066.11.208.0/2066.11.208.1 to 66.11.223.25466.11.223.2554,094
19166.11.224.0/2066.11.224.1 to 66.11.239.25466.11.239.2554,094
19266.11.240.0/2066.11.240.1 to 66.11.255.25466.11.255.2554,094
19366.12.0.0/2066.12.0.1 to 66.12.15.25466.12.15.2554,094
19466.12.16.0/2066.12.16.1 to 66.12.31.25466.12.31.2554,094
19566.12.32.0/2066.12.32.1 to 66.12.47.25466.12.47.2554,094
19666.12.48.0/2066.12.48.1 to 66.12.63.25466.12.63.2554,094
19766.12.64.0/2066.12.64.1 to 66.12.79.25466.12.79.2554,094
19866.12.80.0/2066.12.80.1 to 66.12.95.25466.12.95.2554,094
19966.12.96.0/2066.12.96.1 to 66.12.111.25466.12.111.2554,094
20066.12.112.0/2066.12.112.1 to 66.12.127.25466.12.127.2554,094
20166.12.128.0/2066.12.128.1 to 66.12.143.25466.12.143.2554,094
20266.12.144.0/2066.12.144.1 to 66.12.159.25466.12.159.2554,094
20366.12.160.0/2066.12.160.1 to 66.12.175.25466.12.175.2554,094
20466.12.176.0/2066.12.176.1 to 66.12.191.25466.12.191.2554,094
20566.12.192.0/2066.12.192.1 to 66.12.207.25466.12.207.2554,094
20666.12.208.0/2066.12.208.1 to 66.12.223.25466.12.223.2554,094
20766.12.224.0/2066.12.224.1 to 66.12.239.25466.12.239.2554,094
20866.12.240.0/2066.12.240.1 to 66.12.255.25466.12.255.2554,094
20966.13.0.0/2066.13.0.1 to 66.13.15.25466.13.15.2554,094
21066.13.16.0/2066.13.16.1 to 66.13.31.25466.13.31.2554,094
21166.13.32.0/2066.13.32.1 to 66.13.47.25466.13.47.2554,094
21266.13.48.0/2066.13.48.1 to 66.13.63.25466.13.63.2554,094
21366.13.64.0/2066.13.64.1 to 66.13.79.25466.13.79.2554,094
21466.13.80.0/2066.13.80.1 to 66.13.95.25466.13.95.2554,094
21566.13.96.0/2066.13.96.1 to 66.13.111.25466.13.111.2554,094
21666.13.112.0/2066.13.112.1 to 66.13.127.25466.13.127.2554,094
21766.13.128.0/2066.13.128.1 to 66.13.143.25466.13.143.2554,094
21866.13.144.0/2066.13.144.1 to 66.13.159.25466.13.159.2554,094
21966.13.160.0/2066.13.160.1 to 66.13.175.25466.13.175.2554,094
22066.13.176.0/2066.13.176.1 to 66.13.191.25466.13.191.2554,094
22166.13.192.0/2066.13.192.1 to 66.13.207.25466.13.207.2554,094
22266.13.208.0/2066.13.208.1 to 66.13.223.25466.13.223.2554,094
22366.13.224.0/2066.13.224.1 to 66.13.239.25466.13.239.2554,094
22466.13.240.0/2066.13.240.1 to 66.13.255.25466.13.255.2554,094
22566.14.0.0/2066.14.0.1 to 66.14.15.25466.14.15.2554,094
22666.14.16.0/2066.14.16.1 to 66.14.31.25466.14.31.2554,094
22766.14.32.0/2066.14.32.1 to 66.14.47.25466.14.47.2554,094
22866.14.48.0/2066.14.48.1 to 66.14.63.25466.14.63.2554,094
22966.14.64.0/2066.14.64.1 to 66.14.79.25466.14.79.2554,094
23066.14.80.0/2066.14.80.1 to 66.14.95.25466.14.95.2554,094
23166.14.96.0/2066.14.96.1 to 66.14.111.25466.14.111.2554,094
23266.14.112.0/2066.14.112.1 to 66.14.127.25466.14.127.2554,094
23366.14.128.0/2066.14.128.1 to 66.14.143.25466.14.143.2554,094
23466.14.144.0/2066.14.144.1 to 66.14.159.25466.14.159.2554,094
23566.14.160.0/2066.14.160.1 to 66.14.175.25466.14.175.2554,094
23666.14.176.0/2066.14.176.1 to 66.14.191.25466.14.191.2554,094
23766.14.192.0/2066.14.192.1 to 66.14.207.25466.14.207.2554,094
23866.14.208.0/2066.14.208.1 to 66.14.223.25466.14.223.2554,094
23966.14.224.0/2066.14.224.1 to 66.14.239.25466.14.239.2554,094
24066.14.240.0/2066.14.240.1 to 66.14.255.25466.14.255.2554,094
24166.15.0.0/2066.15.0.1 to 66.15.15.25466.15.15.2554,094
24266.15.16.0/2066.15.16.1 to 66.15.31.25466.15.31.2554,094
24366.15.32.0/2066.15.32.1 to 66.15.47.25466.15.47.2554,094
24466.15.48.0/2066.15.48.1 to 66.15.63.25466.15.63.2554,094
24566.15.64.0/2066.15.64.1 to 66.15.79.25466.15.79.2554,094
24666.15.80.0/2066.15.80.1 to 66.15.95.25466.15.95.2554,094
24766.15.96.0/2066.15.96.1 to 66.15.111.25466.15.111.2554,094
24866.15.112.0/2066.15.112.1 to 66.15.127.25466.15.127.2554,094
24966.15.128.0/2066.15.128.1 to 66.15.143.25466.15.143.2554,094
25066.15.144.0/2066.15.144.1 to 66.15.159.25466.15.159.2554,094
25166.15.160.0/2066.15.160.1 to 66.15.175.25466.15.175.2554,094
25266.15.176.0/2066.15.176.1 to 66.15.191.25466.15.191.2554,094
25366.15.192.0/2066.15.192.1 to 66.15.207.25466.15.207.2554,094
25466.15.208.0/2066.15.208.1 to 66.15.223.25466.15.223.2554,094
25566.15.224.0/2066.15.224.1 to 66.15.239.25466.15.239.2554,094
25666.15.240.0/2066.15.240.1 to 66.15.255.25466.15.255.2554,094

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.