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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.

Network21.192.0.0/11
Usable hosts2,097,150
Subnet mask255.224.0.0
Addresses2,097,152
Network address
21.192.0.0
Broadcast address
21.223.255.255
First usable
21.192.0.1
Last usable
21.223.255.254
Usable hosts
2,097,150 (2,097,152 less the network and broadcast addresses)
Subnet mask
255.224.0.0
Wildcard mask
0.31.255.255 (Cisco ACLs, OSPF)
Prefix length
/11
Type
Public public
Old class
A (default /8)
As numbers
Hex 15C00000 · Integer 364904448 to 367001599
Reverse DNS zones
192.21.in-addr.arpa
193.21.in-addr.arpa
194.21.in-addr.arpa
195.21.in-addr.arpa
196.21.in-addr.arpa
197.21.in-addr.arpa
198.21.in-addr.arpa
199.21.in-addr.arpa
200.21.in-addr.arpa
201.21.in-addr.arpa
202.21.in-addr.arpa
203.21.in-addr.arpa
204.21.in-addr.arpa
205.21.in-addr.arpa
206.21.in-addr.arpa
207.21.in-addr.arpa
and 16 more
/11 is not on a 8-bit boundary, so it takes 32 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00010101.11000000.00000000.0000000021.192.0.0
Subnet mask11111111.11100000.00000000.00000000255.224.0.0
Network00010101.11000000.00000000.0000000021.192.0.0
Broadcast00010101.11011111.11111111.1111111121.223.255.255
Split into smaller subnets/19
/12 (2)/13 (4)/14 (8)/15 (16)/16 (32)/17 (64)/18 (128)/19 (256)/20 (512)/21 (1,024)/22 (2,048)/23 (4,096)

21.192.0.0/11 makes 256 subnets of /19.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
121.192.0.0/1921.192.0.1 to 21.192.31.25421.192.31.2558,190
221.192.32.0/1921.192.32.1 to 21.192.63.25421.192.63.2558,190
321.192.64.0/1921.192.64.1 to 21.192.95.25421.192.95.2558,190
421.192.96.0/1921.192.96.1 to 21.192.127.25421.192.127.2558,190
521.192.128.0/1921.192.128.1 to 21.192.159.25421.192.159.2558,190
621.192.160.0/1921.192.160.1 to 21.192.191.25421.192.191.2558,190
721.192.192.0/1921.192.192.1 to 21.192.223.25421.192.223.2558,190
821.192.224.0/1921.192.224.1 to 21.192.255.25421.192.255.2558,190
921.193.0.0/1921.193.0.1 to 21.193.31.25421.193.31.2558,190
1021.193.32.0/1921.193.32.1 to 21.193.63.25421.193.63.2558,190
1121.193.64.0/1921.193.64.1 to 21.193.95.25421.193.95.2558,190
1221.193.96.0/1921.193.96.1 to 21.193.127.25421.193.127.2558,190
1321.193.128.0/1921.193.128.1 to 21.193.159.25421.193.159.2558,190
1421.193.160.0/1921.193.160.1 to 21.193.191.25421.193.191.2558,190
1521.193.192.0/1921.193.192.1 to 21.193.223.25421.193.223.2558,190
1621.193.224.0/1921.193.224.1 to 21.193.255.25421.193.255.2558,190
1721.194.0.0/1921.194.0.1 to 21.194.31.25421.194.31.2558,190
1821.194.32.0/1921.194.32.1 to 21.194.63.25421.194.63.2558,190
1921.194.64.0/1921.194.64.1 to 21.194.95.25421.194.95.2558,190
2021.194.96.0/1921.194.96.1 to 21.194.127.25421.194.127.2558,190
2121.194.128.0/1921.194.128.1 to 21.194.159.25421.194.159.2558,190
2221.194.160.0/1921.194.160.1 to 21.194.191.25421.194.191.2558,190
2321.194.192.0/1921.194.192.1 to 21.194.223.25421.194.223.2558,190
2421.194.224.0/1921.194.224.1 to 21.194.255.25421.194.255.2558,190
2521.195.0.0/1921.195.0.1 to 21.195.31.25421.195.31.2558,190
2621.195.32.0/1921.195.32.1 to 21.195.63.25421.195.63.2558,190
2721.195.64.0/1921.195.64.1 to 21.195.95.25421.195.95.2558,190
2821.195.96.0/1921.195.96.1 to 21.195.127.25421.195.127.2558,190
2921.195.128.0/1921.195.128.1 to 21.195.159.25421.195.159.2558,190
3021.195.160.0/1921.195.160.1 to 21.195.191.25421.195.191.2558,190
3121.195.192.0/1921.195.192.1 to 21.195.223.25421.195.223.2558,190
3221.195.224.0/1921.195.224.1 to 21.195.255.25421.195.255.2558,190
3321.196.0.0/1921.196.0.1 to 21.196.31.25421.196.31.2558,190
3421.196.32.0/1921.196.32.1 to 21.196.63.25421.196.63.2558,190
3521.196.64.0/1921.196.64.1 to 21.196.95.25421.196.95.2558,190
3621.196.96.0/1921.196.96.1 to 21.196.127.25421.196.127.2558,190
3721.196.128.0/1921.196.128.1 to 21.196.159.25421.196.159.2558,190
3821.196.160.0/1921.196.160.1 to 21.196.191.25421.196.191.2558,190
3921.196.192.0/1921.196.192.1 to 21.196.223.25421.196.223.2558,190
4021.196.224.0/1921.196.224.1 to 21.196.255.25421.196.255.2558,190
4121.197.0.0/1921.197.0.1 to 21.197.31.25421.197.31.2558,190
4221.197.32.0/1921.197.32.1 to 21.197.63.25421.197.63.2558,190
4321.197.64.0/1921.197.64.1 to 21.197.95.25421.197.95.2558,190
4421.197.96.0/1921.197.96.1 to 21.197.127.25421.197.127.2558,190
4521.197.128.0/1921.197.128.1 to 21.197.159.25421.197.159.2558,190
4621.197.160.0/1921.197.160.1 to 21.197.191.25421.197.191.2558,190
4721.197.192.0/1921.197.192.1 to 21.197.223.25421.197.223.2558,190
4821.197.224.0/1921.197.224.1 to 21.197.255.25421.197.255.2558,190
4921.198.0.0/1921.198.0.1 to 21.198.31.25421.198.31.2558,190
5021.198.32.0/1921.198.32.1 to 21.198.63.25421.198.63.2558,190
5121.198.64.0/1921.198.64.1 to 21.198.95.25421.198.95.2558,190
5221.198.96.0/1921.198.96.1 to 21.198.127.25421.198.127.2558,190
5321.198.128.0/1921.198.128.1 to 21.198.159.25421.198.159.2558,190
5421.198.160.0/1921.198.160.1 to 21.198.191.25421.198.191.2558,190
5521.198.192.0/1921.198.192.1 to 21.198.223.25421.198.223.2558,190
5621.198.224.0/1921.198.224.1 to 21.198.255.25421.198.255.2558,190
5721.199.0.0/1921.199.0.1 to 21.199.31.25421.199.31.2558,190
5821.199.32.0/1921.199.32.1 to 21.199.63.25421.199.63.2558,190
5921.199.64.0/1921.199.64.1 to 21.199.95.25421.199.95.2558,190
6021.199.96.0/1921.199.96.1 to 21.199.127.25421.199.127.2558,190
6121.199.128.0/1921.199.128.1 to 21.199.159.25421.199.159.2558,190
6221.199.160.0/1921.199.160.1 to 21.199.191.25421.199.191.2558,190
6321.199.192.0/1921.199.192.1 to 21.199.223.25421.199.223.2558,190
6421.199.224.0/1921.199.224.1 to 21.199.255.25421.199.255.2558,190
6521.200.0.0/1921.200.0.1 to 21.200.31.25421.200.31.2558,190
6621.200.32.0/1921.200.32.1 to 21.200.63.25421.200.63.2558,190
6721.200.64.0/1921.200.64.1 to 21.200.95.25421.200.95.2558,190
6821.200.96.0/1921.200.96.1 to 21.200.127.25421.200.127.2558,190
6921.200.128.0/1921.200.128.1 to 21.200.159.25421.200.159.2558,190
7021.200.160.0/1921.200.160.1 to 21.200.191.25421.200.191.2558,190
7121.200.192.0/1921.200.192.1 to 21.200.223.25421.200.223.2558,190
7221.200.224.0/1921.200.224.1 to 21.200.255.25421.200.255.2558,190
7321.201.0.0/1921.201.0.1 to 21.201.31.25421.201.31.2558,190
7421.201.32.0/1921.201.32.1 to 21.201.63.25421.201.63.2558,190
7521.201.64.0/1921.201.64.1 to 21.201.95.25421.201.95.2558,190
7621.201.96.0/1921.201.96.1 to 21.201.127.25421.201.127.2558,190
7721.201.128.0/1921.201.128.1 to 21.201.159.25421.201.159.2558,190
7821.201.160.0/1921.201.160.1 to 21.201.191.25421.201.191.2558,190
7921.201.192.0/1921.201.192.1 to 21.201.223.25421.201.223.2558,190
8021.201.224.0/1921.201.224.1 to 21.201.255.25421.201.255.2558,190
8121.202.0.0/1921.202.0.1 to 21.202.31.25421.202.31.2558,190
8221.202.32.0/1921.202.32.1 to 21.202.63.25421.202.63.2558,190
8321.202.64.0/1921.202.64.1 to 21.202.95.25421.202.95.2558,190
8421.202.96.0/1921.202.96.1 to 21.202.127.25421.202.127.2558,190
8521.202.128.0/1921.202.128.1 to 21.202.159.25421.202.159.2558,190
8621.202.160.0/1921.202.160.1 to 21.202.191.25421.202.191.2558,190
8721.202.192.0/1921.202.192.1 to 21.202.223.25421.202.223.2558,190
8821.202.224.0/1921.202.224.1 to 21.202.255.25421.202.255.2558,190
8921.203.0.0/1921.203.0.1 to 21.203.31.25421.203.31.2558,190
9021.203.32.0/1921.203.32.1 to 21.203.63.25421.203.63.2558,190
9121.203.64.0/1921.203.64.1 to 21.203.95.25421.203.95.2558,190
9221.203.96.0/1921.203.96.1 to 21.203.127.25421.203.127.2558,190
9321.203.128.0/1921.203.128.1 to 21.203.159.25421.203.159.2558,190
9421.203.160.0/1921.203.160.1 to 21.203.191.25421.203.191.2558,190
9521.203.192.0/1921.203.192.1 to 21.203.223.25421.203.223.2558,190
9621.203.224.0/1921.203.224.1 to 21.203.255.25421.203.255.2558,190
9721.204.0.0/1921.204.0.1 to 21.204.31.25421.204.31.2558,190
9821.204.32.0/1921.204.32.1 to 21.204.63.25421.204.63.2558,190
9921.204.64.0/1921.204.64.1 to 21.204.95.25421.204.95.2558,190
10021.204.96.0/1921.204.96.1 to 21.204.127.25421.204.127.2558,190
10121.204.128.0/1921.204.128.1 to 21.204.159.25421.204.159.2558,190
10221.204.160.0/1921.204.160.1 to 21.204.191.25421.204.191.2558,190
10321.204.192.0/1921.204.192.1 to 21.204.223.25421.204.223.2558,190
10421.204.224.0/1921.204.224.1 to 21.204.255.25421.204.255.2558,190
10521.205.0.0/1921.205.0.1 to 21.205.31.25421.205.31.2558,190
10621.205.32.0/1921.205.32.1 to 21.205.63.25421.205.63.2558,190
10721.205.64.0/1921.205.64.1 to 21.205.95.25421.205.95.2558,190
10821.205.96.0/1921.205.96.1 to 21.205.127.25421.205.127.2558,190
10921.205.128.0/1921.205.128.1 to 21.205.159.25421.205.159.2558,190
11021.205.160.0/1921.205.160.1 to 21.205.191.25421.205.191.2558,190
11121.205.192.0/1921.205.192.1 to 21.205.223.25421.205.223.2558,190
11221.205.224.0/1921.205.224.1 to 21.205.255.25421.205.255.2558,190
11321.206.0.0/1921.206.0.1 to 21.206.31.25421.206.31.2558,190
11421.206.32.0/1921.206.32.1 to 21.206.63.25421.206.63.2558,190
11521.206.64.0/1921.206.64.1 to 21.206.95.25421.206.95.2558,190
11621.206.96.0/1921.206.96.1 to 21.206.127.25421.206.127.2558,190
11721.206.128.0/1921.206.128.1 to 21.206.159.25421.206.159.2558,190
11821.206.160.0/1921.206.160.1 to 21.206.191.25421.206.191.2558,190
11921.206.192.0/1921.206.192.1 to 21.206.223.25421.206.223.2558,190
12021.206.224.0/1921.206.224.1 to 21.206.255.25421.206.255.2558,190
12121.207.0.0/1921.207.0.1 to 21.207.31.25421.207.31.2558,190
12221.207.32.0/1921.207.32.1 to 21.207.63.25421.207.63.2558,190
12321.207.64.0/1921.207.64.1 to 21.207.95.25421.207.95.2558,190
12421.207.96.0/1921.207.96.1 to 21.207.127.25421.207.127.2558,190
12521.207.128.0/1921.207.128.1 to 21.207.159.25421.207.159.2558,190
12621.207.160.0/1921.207.160.1 to 21.207.191.25421.207.191.2558,190
12721.207.192.0/1921.207.192.1 to 21.207.223.25421.207.223.2558,190
12821.207.224.0/1921.207.224.1 to 21.207.255.25421.207.255.2558,190
12921.208.0.0/1921.208.0.1 to 21.208.31.25421.208.31.2558,190
13021.208.32.0/1921.208.32.1 to 21.208.63.25421.208.63.2558,190
13121.208.64.0/1921.208.64.1 to 21.208.95.25421.208.95.2558,190
13221.208.96.0/1921.208.96.1 to 21.208.127.25421.208.127.2558,190
13321.208.128.0/1921.208.128.1 to 21.208.159.25421.208.159.2558,190
13421.208.160.0/1921.208.160.1 to 21.208.191.25421.208.191.2558,190
13521.208.192.0/1921.208.192.1 to 21.208.223.25421.208.223.2558,190
13621.208.224.0/1921.208.224.1 to 21.208.255.25421.208.255.2558,190
13721.209.0.0/1921.209.0.1 to 21.209.31.25421.209.31.2558,190
13821.209.32.0/1921.209.32.1 to 21.209.63.25421.209.63.2558,190
13921.209.64.0/1921.209.64.1 to 21.209.95.25421.209.95.2558,190
14021.209.96.0/1921.209.96.1 to 21.209.127.25421.209.127.2558,190
14121.209.128.0/1921.209.128.1 to 21.209.159.25421.209.159.2558,190
14221.209.160.0/1921.209.160.1 to 21.209.191.25421.209.191.2558,190
14321.209.192.0/1921.209.192.1 to 21.209.223.25421.209.223.2558,190
14421.209.224.0/1921.209.224.1 to 21.209.255.25421.209.255.2558,190
14521.210.0.0/1921.210.0.1 to 21.210.31.25421.210.31.2558,190
14621.210.32.0/1921.210.32.1 to 21.210.63.25421.210.63.2558,190
14721.210.64.0/1921.210.64.1 to 21.210.95.25421.210.95.2558,190
14821.210.96.0/1921.210.96.1 to 21.210.127.25421.210.127.2558,190
14921.210.128.0/1921.210.128.1 to 21.210.159.25421.210.159.2558,190
15021.210.160.0/1921.210.160.1 to 21.210.191.25421.210.191.2558,190
15121.210.192.0/1921.210.192.1 to 21.210.223.25421.210.223.2558,190
15221.210.224.0/1921.210.224.1 to 21.210.255.25421.210.255.2558,190
15321.211.0.0/1921.211.0.1 to 21.211.31.25421.211.31.2558,190
15421.211.32.0/1921.211.32.1 to 21.211.63.25421.211.63.2558,190
15521.211.64.0/1921.211.64.1 to 21.211.95.25421.211.95.2558,190
15621.211.96.0/1921.211.96.1 to 21.211.127.25421.211.127.2558,190
15721.211.128.0/1921.211.128.1 to 21.211.159.25421.211.159.2558,190
15821.211.160.0/1921.211.160.1 to 21.211.191.25421.211.191.2558,190
15921.211.192.0/1921.211.192.1 to 21.211.223.25421.211.223.2558,190
16021.211.224.0/1921.211.224.1 to 21.211.255.25421.211.255.2558,190
16121.212.0.0/1921.212.0.1 to 21.212.31.25421.212.31.2558,190
16221.212.32.0/1921.212.32.1 to 21.212.63.25421.212.63.2558,190
16321.212.64.0/1921.212.64.1 to 21.212.95.25421.212.95.2558,190
16421.212.96.0/1921.212.96.1 to 21.212.127.25421.212.127.2558,190
16521.212.128.0/1921.212.128.1 to 21.212.159.25421.212.159.2558,190
16621.212.160.0/1921.212.160.1 to 21.212.191.25421.212.191.2558,190
16721.212.192.0/1921.212.192.1 to 21.212.223.25421.212.223.2558,190
16821.212.224.0/1921.212.224.1 to 21.212.255.25421.212.255.2558,190
16921.213.0.0/1921.213.0.1 to 21.213.31.25421.213.31.2558,190
17021.213.32.0/1921.213.32.1 to 21.213.63.25421.213.63.2558,190
17121.213.64.0/1921.213.64.1 to 21.213.95.25421.213.95.2558,190
17221.213.96.0/1921.213.96.1 to 21.213.127.25421.213.127.2558,190
17321.213.128.0/1921.213.128.1 to 21.213.159.25421.213.159.2558,190
17421.213.160.0/1921.213.160.1 to 21.213.191.25421.213.191.2558,190
17521.213.192.0/1921.213.192.1 to 21.213.223.25421.213.223.2558,190
17621.213.224.0/1921.213.224.1 to 21.213.255.25421.213.255.2558,190
17721.214.0.0/1921.214.0.1 to 21.214.31.25421.214.31.2558,190
17821.214.32.0/1921.214.32.1 to 21.214.63.25421.214.63.2558,190
17921.214.64.0/1921.214.64.1 to 21.214.95.25421.214.95.2558,190
18021.214.96.0/1921.214.96.1 to 21.214.127.25421.214.127.2558,190
18121.214.128.0/1921.214.128.1 to 21.214.159.25421.214.159.2558,190
18221.214.160.0/1921.214.160.1 to 21.214.191.25421.214.191.2558,190
18321.214.192.0/1921.214.192.1 to 21.214.223.25421.214.223.2558,190
18421.214.224.0/1921.214.224.1 to 21.214.255.25421.214.255.2558,190
18521.215.0.0/1921.215.0.1 to 21.215.31.25421.215.31.2558,190
18621.215.32.0/1921.215.32.1 to 21.215.63.25421.215.63.2558,190
18721.215.64.0/1921.215.64.1 to 21.215.95.25421.215.95.2558,190
18821.215.96.0/1921.215.96.1 to 21.215.127.25421.215.127.2558,190
18921.215.128.0/1921.215.128.1 to 21.215.159.25421.215.159.2558,190
19021.215.160.0/1921.215.160.1 to 21.215.191.25421.215.191.2558,190
19121.215.192.0/1921.215.192.1 to 21.215.223.25421.215.223.2558,190
19221.215.224.0/1921.215.224.1 to 21.215.255.25421.215.255.2558,190
19321.216.0.0/1921.216.0.1 to 21.216.31.25421.216.31.2558,190
19421.216.32.0/1921.216.32.1 to 21.216.63.25421.216.63.2558,190
19521.216.64.0/1921.216.64.1 to 21.216.95.25421.216.95.2558,190
19621.216.96.0/1921.216.96.1 to 21.216.127.25421.216.127.2558,190
19721.216.128.0/1921.216.128.1 to 21.216.159.25421.216.159.2558,190
19821.216.160.0/1921.216.160.1 to 21.216.191.25421.216.191.2558,190
19921.216.192.0/1921.216.192.1 to 21.216.223.25421.216.223.2558,190
20021.216.224.0/1921.216.224.1 to 21.216.255.25421.216.255.2558,190
20121.217.0.0/1921.217.0.1 to 21.217.31.25421.217.31.2558,190
20221.217.32.0/1921.217.32.1 to 21.217.63.25421.217.63.2558,190
20321.217.64.0/1921.217.64.1 to 21.217.95.25421.217.95.2558,190
20421.217.96.0/1921.217.96.1 to 21.217.127.25421.217.127.2558,190
20521.217.128.0/1921.217.128.1 to 21.217.159.25421.217.159.2558,190
20621.217.160.0/1921.217.160.1 to 21.217.191.25421.217.191.2558,190
20721.217.192.0/1921.217.192.1 to 21.217.223.25421.217.223.2558,190
20821.217.224.0/1921.217.224.1 to 21.217.255.25421.217.255.2558,190
20921.218.0.0/1921.218.0.1 to 21.218.31.25421.218.31.2558,190
21021.218.32.0/1921.218.32.1 to 21.218.63.25421.218.63.2558,190
21121.218.64.0/1921.218.64.1 to 21.218.95.25421.218.95.2558,190
21221.218.96.0/1921.218.96.1 to 21.218.127.25421.218.127.2558,190
21321.218.128.0/1921.218.128.1 to 21.218.159.25421.218.159.2558,190
21421.218.160.0/1921.218.160.1 to 21.218.191.25421.218.191.2558,190
21521.218.192.0/1921.218.192.1 to 21.218.223.25421.218.223.2558,190
21621.218.224.0/1921.218.224.1 to 21.218.255.25421.218.255.2558,190
21721.219.0.0/1921.219.0.1 to 21.219.31.25421.219.31.2558,190
21821.219.32.0/1921.219.32.1 to 21.219.63.25421.219.63.2558,190
21921.219.64.0/1921.219.64.1 to 21.219.95.25421.219.95.2558,190
22021.219.96.0/1921.219.96.1 to 21.219.127.25421.219.127.2558,190
22121.219.128.0/1921.219.128.1 to 21.219.159.25421.219.159.2558,190
22221.219.160.0/1921.219.160.1 to 21.219.191.25421.219.191.2558,190
22321.219.192.0/1921.219.192.1 to 21.219.223.25421.219.223.2558,190
22421.219.224.0/1921.219.224.1 to 21.219.255.25421.219.255.2558,190
22521.220.0.0/1921.220.0.1 to 21.220.31.25421.220.31.2558,190
22621.220.32.0/1921.220.32.1 to 21.220.63.25421.220.63.2558,190
22721.220.64.0/1921.220.64.1 to 21.220.95.25421.220.95.2558,190
22821.220.96.0/1921.220.96.1 to 21.220.127.25421.220.127.2558,190
22921.220.128.0/1921.220.128.1 to 21.220.159.25421.220.159.2558,190
23021.220.160.0/1921.220.160.1 to 21.220.191.25421.220.191.2558,190
23121.220.192.0/1921.220.192.1 to 21.220.223.25421.220.223.2558,190
23221.220.224.0/1921.220.224.1 to 21.220.255.25421.220.255.2558,190
23321.221.0.0/1921.221.0.1 to 21.221.31.25421.221.31.2558,190
23421.221.32.0/1921.221.32.1 to 21.221.63.25421.221.63.2558,190
23521.221.64.0/1921.221.64.1 to 21.221.95.25421.221.95.2558,190
23621.221.96.0/1921.221.96.1 to 21.221.127.25421.221.127.2558,190
23721.221.128.0/1921.221.128.1 to 21.221.159.25421.221.159.2558,190
23821.221.160.0/1921.221.160.1 to 21.221.191.25421.221.191.2558,190
23921.221.192.0/1921.221.192.1 to 21.221.223.25421.221.223.2558,190
24021.221.224.0/1921.221.224.1 to 21.221.255.25421.221.255.2558,190
24121.222.0.0/1921.222.0.1 to 21.222.31.25421.222.31.2558,190
24221.222.32.0/1921.222.32.1 to 21.222.63.25421.222.63.2558,190
24321.222.64.0/1921.222.64.1 to 21.222.95.25421.222.95.2558,190
24421.222.96.0/1921.222.96.1 to 21.222.127.25421.222.127.2558,190
24521.222.128.0/1921.222.128.1 to 21.222.159.25421.222.159.2558,190
24621.222.160.0/1921.222.160.1 to 21.222.191.25421.222.191.2558,190
24721.222.192.0/1921.222.192.1 to 21.222.223.25421.222.223.2558,190
24821.222.224.0/1921.222.224.1 to 21.222.255.25421.222.255.2558,190
24921.223.0.0/1921.223.0.1 to 21.223.31.25421.223.31.2558,190
25021.223.32.0/1921.223.32.1 to 21.223.63.25421.223.63.2558,190
25121.223.64.0/1921.223.64.1 to 21.223.95.25421.223.95.2558,190
25221.223.96.0/1921.223.96.1 to 21.223.127.25421.223.127.2558,190
25321.223.128.0/1921.223.128.1 to 21.223.159.25421.223.159.2558,190
25421.223.160.0/1921.223.160.1 to 21.223.191.25421.223.191.2558,190
25521.223.192.0/1921.223.192.1 to 21.223.223.25421.223.223.2558,190
25621.223.224.0/1921.223.224.1 to 21.223.255.25421.223.255.2558,190

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.