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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.

Network66.0.0.0/7
Usable hosts33,554,430
Subnet mask254.0.0.0
Addresses33,554,432
Network address
66.0.0.0
Broadcast address
67.255.255.255
First usable
66.0.0.1
Last usable
67.255.255.254
Usable hosts
33,554,430 (33,554,432 less the network and broadcast addresses)
Subnet mask
254.0.0.0
Wildcard mask
1.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/7
Type
Public public
Old class
A (default /8)
As numbers
Hex 42000000 · Integer 1107296256 to 1140850687
Reverse DNS zones
66.in-addr.arpa
67.in-addr.arpa
/7 is not on a 8-bit boundary, so it takes 2 /8 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01000010.00000000.00000000.0000000066.0.0.0
Subnet mask11111110.00000000.00000000.00000000254.0.0.0
Network01000010.00000000.00000000.0000000066.0.0.0
Broadcast01000011.11111111.11111111.1111111167.255.255.255
Split into smaller subnets/19
/8 (2)/9 (4)/10 (8)/11 (16)/12 (32)/13 (64)/14 (128)/15 (256)/16 (512)/17 (1,024)/18 (2,048)/19 (4,096)

66.0.0.0/7 makes 4,096 subnets of /19; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
166.0.0.0/1966.0.0.1 to 66.0.31.25466.0.31.2558,190
266.0.32.0/1966.0.32.1 to 66.0.63.25466.0.63.2558,190
366.0.64.0/1966.0.64.1 to 66.0.95.25466.0.95.2558,190
466.0.96.0/1966.0.96.1 to 66.0.127.25466.0.127.2558,190
566.0.128.0/1966.0.128.1 to 66.0.159.25466.0.159.2558,190
666.0.160.0/1966.0.160.1 to 66.0.191.25466.0.191.2558,190
766.0.192.0/1966.0.192.1 to 66.0.223.25466.0.223.2558,190
866.0.224.0/1966.0.224.1 to 66.0.255.25466.0.255.2558,190
966.1.0.0/1966.1.0.1 to 66.1.31.25466.1.31.2558,190
1066.1.32.0/1966.1.32.1 to 66.1.63.25466.1.63.2558,190
1166.1.64.0/1966.1.64.1 to 66.1.95.25466.1.95.2558,190
1266.1.96.0/1966.1.96.1 to 66.1.127.25466.1.127.2558,190
1366.1.128.0/1966.1.128.1 to 66.1.159.25466.1.159.2558,190
1466.1.160.0/1966.1.160.1 to 66.1.191.25466.1.191.2558,190
1566.1.192.0/1966.1.192.1 to 66.1.223.25466.1.223.2558,190
1666.1.224.0/1966.1.224.1 to 66.1.255.25466.1.255.2558,190
1766.2.0.0/1966.2.0.1 to 66.2.31.25466.2.31.2558,190
1866.2.32.0/1966.2.32.1 to 66.2.63.25466.2.63.2558,190
1966.2.64.0/1966.2.64.1 to 66.2.95.25466.2.95.2558,190
2066.2.96.0/1966.2.96.1 to 66.2.127.25466.2.127.2558,190
2166.2.128.0/1966.2.128.1 to 66.2.159.25466.2.159.2558,190
2266.2.160.0/1966.2.160.1 to 66.2.191.25466.2.191.2558,190
2366.2.192.0/1966.2.192.1 to 66.2.223.25466.2.223.2558,190
2466.2.224.0/1966.2.224.1 to 66.2.255.25466.2.255.2558,190
2566.3.0.0/1966.3.0.1 to 66.3.31.25466.3.31.2558,190
2666.3.32.0/1966.3.32.1 to 66.3.63.25466.3.63.2558,190
2766.3.64.0/1966.3.64.1 to 66.3.95.25466.3.95.2558,190
2866.3.96.0/1966.3.96.1 to 66.3.127.25466.3.127.2558,190
2966.3.128.0/1966.3.128.1 to 66.3.159.25466.3.159.2558,190
3066.3.160.0/1966.3.160.1 to 66.3.191.25466.3.191.2558,190
3166.3.192.0/1966.3.192.1 to 66.3.223.25466.3.223.2558,190
3266.3.224.0/1966.3.224.1 to 66.3.255.25466.3.255.2558,190
3366.4.0.0/1966.4.0.1 to 66.4.31.25466.4.31.2558,190
3466.4.32.0/1966.4.32.1 to 66.4.63.25466.4.63.2558,190
3566.4.64.0/1966.4.64.1 to 66.4.95.25466.4.95.2558,190
3666.4.96.0/1966.4.96.1 to 66.4.127.25466.4.127.2558,190
3766.4.128.0/1966.4.128.1 to 66.4.159.25466.4.159.2558,190
3866.4.160.0/1966.4.160.1 to 66.4.191.25466.4.191.2558,190
3966.4.192.0/1966.4.192.1 to 66.4.223.25466.4.223.2558,190
4066.4.224.0/1966.4.224.1 to 66.4.255.25466.4.255.2558,190
4166.5.0.0/1966.5.0.1 to 66.5.31.25466.5.31.2558,190
4266.5.32.0/1966.5.32.1 to 66.5.63.25466.5.63.2558,190
4366.5.64.0/1966.5.64.1 to 66.5.95.25466.5.95.2558,190
4466.5.96.0/1966.5.96.1 to 66.5.127.25466.5.127.2558,190
4566.5.128.0/1966.5.128.1 to 66.5.159.25466.5.159.2558,190
4666.5.160.0/1966.5.160.1 to 66.5.191.25466.5.191.2558,190
4766.5.192.0/1966.5.192.1 to 66.5.223.25466.5.223.2558,190
4866.5.224.0/1966.5.224.1 to 66.5.255.25466.5.255.2558,190
4966.6.0.0/1966.6.0.1 to 66.6.31.25466.6.31.2558,190
5066.6.32.0/1966.6.32.1 to 66.6.63.25466.6.63.2558,190
5166.6.64.0/1966.6.64.1 to 66.6.95.25466.6.95.2558,190
5266.6.96.0/1966.6.96.1 to 66.6.127.25466.6.127.2558,190
5366.6.128.0/1966.6.128.1 to 66.6.159.25466.6.159.2558,190
5466.6.160.0/1966.6.160.1 to 66.6.191.25466.6.191.2558,190
5566.6.192.0/1966.6.192.1 to 66.6.223.25466.6.223.2558,190
5666.6.224.0/1966.6.224.1 to 66.6.255.25466.6.255.2558,190
5766.7.0.0/1966.7.0.1 to 66.7.31.25466.7.31.2558,190
5866.7.32.0/1966.7.32.1 to 66.7.63.25466.7.63.2558,190
5966.7.64.0/1966.7.64.1 to 66.7.95.25466.7.95.2558,190
6066.7.96.0/1966.7.96.1 to 66.7.127.25466.7.127.2558,190
6166.7.128.0/1966.7.128.1 to 66.7.159.25466.7.159.2558,190
6266.7.160.0/1966.7.160.1 to 66.7.191.25466.7.191.2558,190
6366.7.192.0/1966.7.192.1 to 66.7.223.25466.7.223.2558,190
6466.7.224.0/1966.7.224.1 to 66.7.255.25466.7.255.2558,190
6566.8.0.0/1966.8.0.1 to 66.8.31.25466.8.31.2558,190
6666.8.32.0/1966.8.32.1 to 66.8.63.25466.8.63.2558,190
6766.8.64.0/1966.8.64.1 to 66.8.95.25466.8.95.2558,190
6866.8.96.0/1966.8.96.1 to 66.8.127.25466.8.127.2558,190
6966.8.128.0/1966.8.128.1 to 66.8.159.25466.8.159.2558,190
7066.8.160.0/1966.8.160.1 to 66.8.191.25466.8.191.2558,190
7166.8.192.0/1966.8.192.1 to 66.8.223.25466.8.223.2558,190
7266.8.224.0/1966.8.224.1 to 66.8.255.25466.8.255.2558,190
7366.9.0.0/1966.9.0.1 to 66.9.31.25466.9.31.2558,190
7466.9.32.0/1966.9.32.1 to 66.9.63.25466.9.63.2558,190
7566.9.64.0/1966.9.64.1 to 66.9.95.25466.9.95.2558,190
7666.9.96.0/1966.9.96.1 to 66.9.127.25466.9.127.2558,190
7766.9.128.0/1966.9.128.1 to 66.9.159.25466.9.159.2558,190
7866.9.160.0/1966.9.160.1 to 66.9.191.25466.9.191.2558,190
7966.9.192.0/1966.9.192.1 to 66.9.223.25466.9.223.2558,190
8066.9.224.0/1966.9.224.1 to 66.9.255.25466.9.255.2558,190
8166.10.0.0/1966.10.0.1 to 66.10.31.25466.10.31.2558,190
8266.10.32.0/1966.10.32.1 to 66.10.63.25466.10.63.2558,190
8366.10.64.0/1966.10.64.1 to 66.10.95.25466.10.95.2558,190
8466.10.96.0/1966.10.96.1 to 66.10.127.25466.10.127.2558,190
8566.10.128.0/1966.10.128.1 to 66.10.159.25466.10.159.2558,190
8666.10.160.0/1966.10.160.1 to 66.10.191.25466.10.191.2558,190
8766.10.192.0/1966.10.192.1 to 66.10.223.25466.10.223.2558,190
8866.10.224.0/1966.10.224.1 to 66.10.255.25466.10.255.2558,190
8966.11.0.0/1966.11.0.1 to 66.11.31.25466.11.31.2558,190
9066.11.32.0/1966.11.32.1 to 66.11.63.25466.11.63.2558,190
9166.11.64.0/1966.11.64.1 to 66.11.95.25466.11.95.2558,190
9266.11.96.0/1966.11.96.1 to 66.11.127.25466.11.127.2558,190
9366.11.128.0/1966.11.128.1 to 66.11.159.25466.11.159.2558,190
9466.11.160.0/1966.11.160.1 to 66.11.191.25466.11.191.2558,190
9566.11.192.0/1966.11.192.1 to 66.11.223.25466.11.223.2558,190
9666.11.224.0/1966.11.224.1 to 66.11.255.25466.11.255.2558,190
9766.12.0.0/1966.12.0.1 to 66.12.31.25466.12.31.2558,190
9866.12.32.0/1966.12.32.1 to 66.12.63.25466.12.63.2558,190
9966.12.64.0/1966.12.64.1 to 66.12.95.25466.12.95.2558,190
10066.12.96.0/1966.12.96.1 to 66.12.127.25466.12.127.2558,190
10166.12.128.0/1966.12.128.1 to 66.12.159.25466.12.159.2558,190
10266.12.160.0/1966.12.160.1 to 66.12.191.25466.12.191.2558,190
10366.12.192.0/1966.12.192.1 to 66.12.223.25466.12.223.2558,190
10466.12.224.0/1966.12.224.1 to 66.12.255.25466.12.255.2558,190
10566.13.0.0/1966.13.0.1 to 66.13.31.25466.13.31.2558,190
10666.13.32.0/1966.13.32.1 to 66.13.63.25466.13.63.2558,190
10766.13.64.0/1966.13.64.1 to 66.13.95.25466.13.95.2558,190
10866.13.96.0/1966.13.96.1 to 66.13.127.25466.13.127.2558,190
10966.13.128.0/1966.13.128.1 to 66.13.159.25466.13.159.2558,190
11066.13.160.0/1966.13.160.1 to 66.13.191.25466.13.191.2558,190
11166.13.192.0/1966.13.192.1 to 66.13.223.25466.13.223.2558,190
11266.13.224.0/1966.13.224.1 to 66.13.255.25466.13.255.2558,190
11366.14.0.0/1966.14.0.1 to 66.14.31.25466.14.31.2558,190
11466.14.32.0/1966.14.32.1 to 66.14.63.25466.14.63.2558,190
11566.14.64.0/1966.14.64.1 to 66.14.95.25466.14.95.2558,190
11666.14.96.0/1966.14.96.1 to 66.14.127.25466.14.127.2558,190
11766.14.128.0/1966.14.128.1 to 66.14.159.25466.14.159.2558,190
11866.14.160.0/1966.14.160.1 to 66.14.191.25466.14.191.2558,190
11966.14.192.0/1966.14.192.1 to 66.14.223.25466.14.223.2558,190
12066.14.224.0/1966.14.224.1 to 66.14.255.25466.14.255.2558,190
12166.15.0.0/1966.15.0.1 to 66.15.31.25466.15.31.2558,190
12266.15.32.0/1966.15.32.1 to 66.15.63.25466.15.63.2558,190
12366.15.64.0/1966.15.64.1 to 66.15.95.25466.15.95.2558,190
12466.15.96.0/1966.15.96.1 to 66.15.127.25466.15.127.2558,190
12566.15.128.0/1966.15.128.1 to 66.15.159.25466.15.159.2558,190
12666.15.160.0/1966.15.160.1 to 66.15.191.25466.15.191.2558,190
12766.15.192.0/1966.15.192.1 to 66.15.223.25466.15.223.2558,190
12866.15.224.0/1966.15.224.1 to 66.15.255.25466.15.255.2558,190
12966.16.0.0/1966.16.0.1 to 66.16.31.25466.16.31.2558,190
13066.16.32.0/1966.16.32.1 to 66.16.63.25466.16.63.2558,190
13166.16.64.0/1966.16.64.1 to 66.16.95.25466.16.95.2558,190
13266.16.96.0/1966.16.96.1 to 66.16.127.25466.16.127.2558,190
13366.16.128.0/1966.16.128.1 to 66.16.159.25466.16.159.2558,190
13466.16.160.0/1966.16.160.1 to 66.16.191.25466.16.191.2558,190
13566.16.192.0/1966.16.192.1 to 66.16.223.25466.16.223.2558,190
13666.16.224.0/1966.16.224.1 to 66.16.255.25466.16.255.2558,190
13766.17.0.0/1966.17.0.1 to 66.17.31.25466.17.31.2558,190
13866.17.32.0/1966.17.32.1 to 66.17.63.25466.17.63.2558,190
13966.17.64.0/1966.17.64.1 to 66.17.95.25466.17.95.2558,190
14066.17.96.0/1966.17.96.1 to 66.17.127.25466.17.127.2558,190
14166.17.128.0/1966.17.128.1 to 66.17.159.25466.17.159.2558,190
14266.17.160.0/1966.17.160.1 to 66.17.191.25466.17.191.2558,190
14366.17.192.0/1966.17.192.1 to 66.17.223.25466.17.223.2558,190
14466.17.224.0/1966.17.224.1 to 66.17.255.25466.17.255.2558,190
14566.18.0.0/1966.18.0.1 to 66.18.31.25466.18.31.2558,190
14666.18.32.0/1966.18.32.1 to 66.18.63.25466.18.63.2558,190
14766.18.64.0/1966.18.64.1 to 66.18.95.25466.18.95.2558,190
14866.18.96.0/1966.18.96.1 to 66.18.127.25466.18.127.2558,190
14966.18.128.0/1966.18.128.1 to 66.18.159.25466.18.159.2558,190
15066.18.160.0/1966.18.160.1 to 66.18.191.25466.18.191.2558,190
15166.18.192.0/1966.18.192.1 to 66.18.223.25466.18.223.2558,190
15266.18.224.0/1966.18.224.1 to 66.18.255.25466.18.255.2558,190
15366.19.0.0/1966.19.0.1 to 66.19.31.25466.19.31.2558,190
15466.19.32.0/1966.19.32.1 to 66.19.63.25466.19.63.2558,190
15566.19.64.0/1966.19.64.1 to 66.19.95.25466.19.95.2558,190
15666.19.96.0/1966.19.96.1 to 66.19.127.25466.19.127.2558,190
15766.19.128.0/1966.19.128.1 to 66.19.159.25466.19.159.2558,190
15866.19.160.0/1966.19.160.1 to 66.19.191.25466.19.191.2558,190
15966.19.192.0/1966.19.192.1 to 66.19.223.25466.19.223.2558,190
16066.19.224.0/1966.19.224.1 to 66.19.255.25466.19.255.2558,190
16166.20.0.0/1966.20.0.1 to 66.20.31.25466.20.31.2558,190
16266.20.32.0/1966.20.32.1 to 66.20.63.25466.20.63.2558,190
16366.20.64.0/1966.20.64.1 to 66.20.95.25466.20.95.2558,190
16466.20.96.0/1966.20.96.1 to 66.20.127.25466.20.127.2558,190
16566.20.128.0/1966.20.128.1 to 66.20.159.25466.20.159.2558,190
16666.20.160.0/1966.20.160.1 to 66.20.191.25466.20.191.2558,190
16766.20.192.0/1966.20.192.1 to 66.20.223.25466.20.223.2558,190
16866.20.224.0/1966.20.224.1 to 66.20.255.25466.20.255.2558,190
16966.21.0.0/1966.21.0.1 to 66.21.31.25466.21.31.2558,190
17066.21.32.0/1966.21.32.1 to 66.21.63.25466.21.63.2558,190
17166.21.64.0/1966.21.64.1 to 66.21.95.25466.21.95.2558,190
17266.21.96.0/1966.21.96.1 to 66.21.127.25466.21.127.2558,190
17366.21.128.0/1966.21.128.1 to 66.21.159.25466.21.159.2558,190
17466.21.160.0/1966.21.160.1 to 66.21.191.25466.21.191.2558,190
17566.21.192.0/1966.21.192.1 to 66.21.223.25466.21.223.2558,190
17666.21.224.0/1966.21.224.1 to 66.21.255.25466.21.255.2558,190
17766.22.0.0/1966.22.0.1 to 66.22.31.25466.22.31.2558,190
17866.22.32.0/1966.22.32.1 to 66.22.63.25466.22.63.2558,190
17966.22.64.0/1966.22.64.1 to 66.22.95.25466.22.95.2558,190
18066.22.96.0/1966.22.96.1 to 66.22.127.25466.22.127.2558,190
18166.22.128.0/1966.22.128.1 to 66.22.159.25466.22.159.2558,190
18266.22.160.0/1966.22.160.1 to 66.22.191.25466.22.191.2558,190
18366.22.192.0/1966.22.192.1 to 66.22.223.25466.22.223.2558,190
18466.22.224.0/1966.22.224.1 to 66.22.255.25466.22.255.2558,190
18566.23.0.0/1966.23.0.1 to 66.23.31.25466.23.31.2558,190
18666.23.32.0/1966.23.32.1 to 66.23.63.25466.23.63.2558,190
18766.23.64.0/1966.23.64.1 to 66.23.95.25466.23.95.2558,190
18866.23.96.0/1966.23.96.1 to 66.23.127.25466.23.127.2558,190
18966.23.128.0/1966.23.128.1 to 66.23.159.25466.23.159.2558,190
19066.23.160.0/1966.23.160.1 to 66.23.191.25466.23.191.2558,190
19166.23.192.0/1966.23.192.1 to 66.23.223.25466.23.223.2558,190
19266.23.224.0/1966.23.224.1 to 66.23.255.25466.23.255.2558,190
19366.24.0.0/1966.24.0.1 to 66.24.31.25466.24.31.2558,190
19466.24.32.0/1966.24.32.1 to 66.24.63.25466.24.63.2558,190
19566.24.64.0/1966.24.64.1 to 66.24.95.25466.24.95.2558,190
19666.24.96.0/1966.24.96.1 to 66.24.127.25466.24.127.2558,190
19766.24.128.0/1966.24.128.1 to 66.24.159.25466.24.159.2558,190
19866.24.160.0/1966.24.160.1 to 66.24.191.25466.24.191.2558,190
19966.24.192.0/1966.24.192.1 to 66.24.223.25466.24.223.2558,190
20066.24.224.0/1966.24.224.1 to 66.24.255.25466.24.255.2558,190
20166.25.0.0/1966.25.0.1 to 66.25.31.25466.25.31.2558,190
20266.25.32.0/1966.25.32.1 to 66.25.63.25466.25.63.2558,190
20366.25.64.0/1966.25.64.1 to 66.25.95.25466.25.95.2558,190
20466.25.96.0/1966.25.96.1 to 66.25.127.25466.25.127.2558,190
20566.25.128.0/1966.25.128.1 to 66.25.159.25466.25.159.2558,190
20666.25.160.0/1966.25.160.1 to 66.25.191.25466.25.191.2558,190
20766.25.192.0/1966.25.192.1 to 66.25.223.25466.25.223.2558,190
20866.25.224.0/1966.25.224.1 to 66.25.255.25466.25.255.2558,190
20966.26.0.0/1966.26.0.1 to 66.26.31.25466.26.31.2558,190
21066.26.32.0/1966.26.32.1 to 66.26.63.25466.26.63.2558,190
21166.26.64.0/1966.26.64.1 to 66.26.95.25466.26.95.2558,190
21266.26.96.0/1966.26.96.1 to 66.26.127.25466.26.127.2558,190
21366.26.128.0/1966.26.128.1 to 66.26.159.25466.26.159.2558,190
21466.26.160.0/1966.26.160.1 to 66.26.191.25466.26.191.2558,190
21566.26.192.0/1966.26.192.1 to 66.26.223.25466.26.223.2558,190
21666.26.224.0/1966.26.224.1 to 66.26.255.25466.26.255.2558,190
21766.27.0.0/1966.27.0.1 to 66.27.31.25466.27.31.2558,190
21866.27.32.0/1966.27.32.1 to 66.27.63.25466.27.63.2558,190
21966.27.64.0/1966.27.64.1 to 66.27.95.25466.27.95.2558,190
22066.27.96.0/1966.27.96.1 to 66.27.127.25466.27.127.2558,190
22166.27.128.0/1966.27.128.1 to 66.27.159.25466.27.159.2558,190
22266.27.160.0/1966.27.160.1 to 66.27.191.25466.27.191.2558,190
22366.27.192.0/1966.27.192.1 to 66.27.223.25466.27.223.2558,190
22466.27.224.0/1966.27.224.1 to 66.27.255.25466.27.255.2558,190
22566.28.0.0/1966.28.0.1 to 66.28.31.25466.28.31.2558,190
22666.28.32.0/1966.28.32.1 to 66.28.63.25466.28.63.2558,190
22766.28.64.0/1966.28.64.1 to 66.28.95.25466.28.95.2558,190
22866.28.96.0/1966.28.96.1 to 66.28.127.25466.28.127.2558,190
22966.28.128.0/1966.28.128.1 to 66.28.159.25466.28.159.2558,190
23066.28.160.0/1966.28.160.1 to 66.28.191.25466.28.191.2558,190
23166.28.192.0/1966.28.192.1 to 66.28.223.25466.28.223.2558,190
23266.28.224.0/1966.28.224.1 to 66.28.255.25466.28.255.2558,190
23366.29.0.0/1966.29.0.1 to 66.29.31.25466.29.31.2558,190
23466.29.32.0/1966.29.32.1 to 66.29.63.25466.29.63.2558,190
23566.29.64.0/1966.29.64.1 to 66.29.95.25466.29.95.2558,190
23666.29.96.0/1966.29.96.1 to 66.29.127.25466.29.127.2558,190
23766.29.128.0/1966.29.128.1 to 66.29.159.25466.29.159.2558,190
23866.29.160.0/1966.29.160.1 to 66.29.191.25466.29.191.2558,190
23966.29.192.0/1966.29.192.1 to 66.29.223.25466.29.223.2558,190
24066.29.224.0/1966.29.224.1 to 66.29.255.25466.29.255.2558,190
24166.30.0.0/1966.30.0.1 to 66.30.31.25466.30.31.2558,190
24266.30.32.0/1966.30.32.1 to 66.30.63.25466.30.63.2558,190
24366.30.64.0/1966.30.64.1 to 66.30.95.25466.30.95.2558,190
24466.30.96.0/1966.30.96.1 to 66.30.127.25466.30.127.2558,190
24566.30.128.0/1966.30.128.1 to 66.30.159.25466.30.159.2558,190
24666.30.160.0/1966.30.160.1 to 66.30.191.25466.30.191.2558,190
24766.30.192.0/1966.30.192.1 to 66.30.223.25466.30.223.2558,190
24866.30.224.0/1966.30.224.1 to 66.30.255.25466.30.255.2558,190
24966.31.0.0/1966.31.0.1 to 66.31.31.25466.31.31.2558,190
25066.31.32.0/1966.31.32.1 to 66.31.63.25466.31.63.2558,190
25166.31.64.0/1966.31.64.1 to 66.31.95.25466.31.95.2558,190
25266.31.96.0/1966.31.96.1 to 66.31.127.25466.31.127.2558,190
25366.31.128.0/1966.31.128.1 to 66.31.159.25466.31.159.2558,190
25466.31.160.0/1966.31.160.1 to 66.31.191.25466.31.191.2558,190
25566.31.192.0/1966.31.192.1 to 66.31.223.25466.31.223.2558,190
25666.31.224.0/1966.31.224.1 to 66.31.255.25466.31.255.2558,190

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.