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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.

Network15.192.0.0/12
Usable hosts1,048,574
Subnet mask255.240.0.0
Addresses1,048,576
Network address
15.192.0.0
Broadcast address
15.207.255.255
First usable
15.192.0.1
Last usable
15.207.255.254
Usable hosts
1,048,574 (1,048,576 less the network and broadcast addresses)
Subnet mask
255.240.0.0
Wildcard mask
0.15.255.255 (Cisco ACLs, OSPF)
Prefix length
/12
Type
Public public
Old class
A (default /8)
As numbers
Hex 0FC00000 · Integer 264241152 to 265289727
Reverse DNS zones
192.15.in-addr.arpa
193.15.in-addr.arpa
194.15.in-addr.arpa
195.15.in-addr.arpa
196.15.in-addr.arpa
197.15.in-addr.arpa
198.15.in-addr.arpa
199.15.in-addr.arpa
200.15.in-addr.arpa
201.15.in-addr.arpa
202.15.in-addr.arpa
203.15.in-addr.arpa
204.15.in-addr.arpa
205.15.in-addr.arpa
206.15.in-addr.arpa
207.15.in-addr.arpa
/12 is not on a 8-bit boundary, so it takes 16 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00001111.11000000.00000000.0000000015.192.0.0
Subnet mask11111111.11110000.00000000.00000000255.240.0.0
Network00001111.11000000.00000000.0000000015.192.0.0
Broadcast00001111.11001111.11111111.1111111115.207.255.255
Split into smaller subnets/20
/13 (2)/14 (4)/15 (8)/16 (16)/17 (32)/18 (64)/19 (128)/20 (256)/21 (512)/22 (1,024)/23 (2,048)/24 (4,096)

15.192.0.0/12 makes 256 subnets of /20.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
115.192.0.0/2015.192.0.1 to 15.192.15.25415.192.15.2554,094
215.192.16.0/2015.192.16.1 to 15.192.31.25415.192.31.2554,094
315.192.32.0/2015.192.32.1 to 15.192.47.25415.192.47.2554,094
415.192.48.0/2015.192.48.1 to 15.192.63.25415.192.63.2554,094
515.192.64.0/2015.192.64.1 to 15.192.79.25415.192.79.2554,094
615.192.80.0/2015.192.80.1 to 15.192.95.25415.192.95.2554,094
715.192.96.0/2015.192.96.1 to 15.192.111.25415.192.111.2554,094
815.192.112.0/2015.192.112.1 to 15.192.127.25415.192.127.2554,094
915.192.128.0/2015.192.128.1 to 15.192.143.25415.192.143.2554,094
1015.192.144.0/2015.192.144.1 to 15.192.159.25415.192.159.2554,094
1115.192.160.0/2015.192.160.1 to 15.192.175.25415.192.175.2554,094
1215.192.176.0/2015.192.176.1 to 15.192.191.25415.192.191.2554,094
1315.192.192.0/2015.192.192.1 to 15.192.207.25415.192.207.2554,094
1415.192.208.0/2015.192.208.1 to 15.192.223.25415.192.223.2554,094
1515.192.224.0/2015.192.224.1 to 15.192.239.25415.192.239.2554,094
1615.192.240.0/2015.192.240.1 to 15.192.255.25415.192.255.2554,094
1715.193.0.0/2015.193.0.1 to 15.193.15.25415.193.15.2554,094
1815.193.16.0/2015.193.16.1 to 15.193.31.25415.193.31.2554,094
1915.193.32.0/2015.193.32.1 to 15.193.47.25415.193.47.2554,094
2015.193.48.0/2015.193.48.1 to 15.193.63.25415.193.63.2554,094
2115.193.64.0/2015.193.64.1 to 15.193.79.25415.193.79.2554,094
2215.193.80.0/2015.193.80.1 to 15.193.95.25415.193.95.2554,094
2315.193.96.0/2015.193.96.1 to 15.193.111.25415.193.111.2554,094
2415.193.112.0/2015.193.112.1 to 15.193.127.25415.193.127.2554,094
2515.193.128.0/2015.193.128.1 to 15.193.143.25415.193.143.2554,094
2615.193.144.0/2015.193.144.1 to 15.193.159.25415.193.159.2554,094
2715.193.160.0/2015.193.160.1 to 15.193.175.25415.193.175.2554,094
2815.193.176.0/2015.193.176.1 to 15.193.191.25415.193.191.2554,094
2915.193.192.0/2015.193.192.1 to 15.193.207.25415.193.207.2554,094
3015.193.208.0/2015.193.208.1 to 15.193.223.25415.193.223.2554,094
3115.193.224.0/2015.193.224.1 to 15.193.239.25415.193.239.2554,094
3215.193.240.0/2015.193.240.1 to 15.193.255.25415.193.255.2554,094
3315.194.0.0/2015.194.0.1 to 15.194.15.25415.194.15.2554,094
3415.194.16.0/2015.194.16.1 to 15.194.31.25415.194.31.2554,094
3515.194.32.0/2015.194.32.1 to 15.194.47.25415.194.47.2554,094
3615.194.48.0/2015.194.48.1 to 15.194.63.25415.194.63.2554,094
3715.194.64.0/2015.194.64.1 to 15.194.79.25415.194.79.2554,094
3815.194.80.0/2015.194.80.1 to 15.194.95.25415.194.95.2554,094
3915.194.96.0/2015.194.96.1 to 15.194.111.25415.194.111.2554,094
4015.194.112.0/2015.194.112.1 to 15.194.127.25415.194.127.2554,094
4115.194.128.0/2015.194.128.1 to 15.194.143.25415.194.143.2554,094
4215.194.144.0/2015.194.144.1 to 15.194.159.25415.194.159.2554,094
4315.194.160.0/2015.194.160.1 to 15.194.175.25415.194.175.2554,094
4415.194.176.0/2015.194.176.1 to 15.194.191.25415.194.191.2554,094
4515.194.192.0/2015.194.192.1 to 15.194.207.25415.194.207.2554,094
4615.194.208.0/2015.194.208.1 to 15.194.223.25415.194.223.2554,094
4715.194.224.0/2015.194.224.1 to 15.194.239.25415.194.239.2554,094
4815.194.240.0/2015.194.240.1 to 15.194.255.25415.194.255.2554,094
4915.195.0.0/2015.195.0.1 to 15.195.15.25415.195.15.2554,094
5015.195.16.0/2015.195.16.1 to 15.195.31.25415.195.31.2554,094
5115.195.32.0/2015.195.32.1 to 15.195.47.25415.195.47.2554,094
5215.195.48.0/2015.195.48.1 to 15.195.63.25415.195.63.2554,094
5315.195.64.0/2015.195.64.1 to 15.195.79.25415.195.79.2554,094
5415.195.80.0/2015.195.80.1 to 15.195.95.25415.195.95.2554,094
5515.195.96.0/2015.195.96.1 to 15.195.111.25415.195.111.2554,094
5615.195.112.0/2015.195.112.1 to 15.195.127.25415.195.127.2554,094
5715.195.128.0/2015.195.128.1 to 15.195.143.25415.195.143.2554,094
5815.195.144.0/2015.195.144.1 to 15.195.159.25415.195.159.2554,094
5915.195.160.0/2015.195.160.1 to 15.195.175.25415.195.175.2554,094
6015.195.176.0/2015.195.176.1 to 15.195.191.25415.195.191.2554,094
6115.195.192.0/2015.195.192.1 to 15.195.207.25415.195.207.2554,094
6215.195.208.0/2015.195.208.1 to 15.195.223.25415.195.223.2554,094
6315.195.224.0/2015.195.224.1 to 15.195.239.25415.195.239.2554,094
6415.195.240.0/2015.195.240.1 to 15.195.255.25415.195.255.2554,094
6515.196.0.0/2015.196.0.1 to 15.196.15.25415.196.15.2554,094
6615.196.16.0/2015.196.16.1 to 15.196.31.25415.196.31.2554,094
6715.196.32.0/2015.196.32.1 to 15.196.47.25415.196.47.2554,094
6815.196.48.0/2015.196.48.1 to 15.196.63.25415.196.63.2554,094
6915.196.64.0/2015.196.64.1 to 15.196.79.25415.196.79.2554,094
7015.196.80.0/2015.196.80.1 to 15.196.95.25415.196.95.2554,094
7115.196.96.0/2015.196.96.1 to 15.196.111.25415.196.111.2554,094
7215.196.112.0/2015.196.112.1 to 15.196.127.25415.196.127.2554,094
7315.196.128.0/2015.196.128.1 to 15.196.143.25415.196.143.2554,094
7415.196.144.0/2015.196.144.1 to 15.196.159.25415.196.159.2554,094
7515.196.160.0/2015.196.160.1 to 15.196.175.25415.196.175.2554,094
7615.196.176.0/2015.196.176.1 to 15.196.191.25415.196.191.2554,094
7715.196.192.0/2015.196.192.1 to 15.196.207.25415.196.207.2554,094
7815.196.208.0/2015.196.208.1 to 15.196.223.25415.196.223.2554,094
7915.196.224.0/2015.196.224.1 to 15.196.239.25415.196.239.2554,094
8015.196.240.0/2015.196.240.1 to 15.196.255.25415.196.255.2554,094
8115.197.0.0/2015.197.0.1 to 15.197.15.25415.197.15.2554,094
8215.197.16.0/2015.197.16.1 to 15.197.31.25415.197.31.2554,094
8315.197.32.0/2015.197.32.1 to 15.197.47.25415.197.47.2554,094
8415.197.48.0/2015.197.48.1 to 15.197.63.25415.197.63.2554,094
8515.197.64.0/2015.197.64.1 to 15.197.79.25415.197.79.2554,094
8615.197.80.0/2015.197.80.1 to 15.197.95.25415.197.95.2554,094
8715.197.96.0/2015.197.96.1 to 15.197.111.25415.197.111.2554,094
8815.197.112.0/2015.197.112.1 to 15.197.127.25415.197.127.2554,094
8915.197.128.0/2015.197.128.1 to 15.197.143.25415.197.143.2554,094
9015.197.144.0/2015.197.144.1 to 15.197.159.25415.197.159.2554,094
9115.197.160.0/2015.197.160.1 to 15.197.175.25415.197.175.2554,094
9215.197.176.0/2015.197.176.1 to 15.197.191.25415.197.191.2554,094
9315.197.192.0/2015.197.192.1 to 15.197.207.25415.197.207.2554,094
9415.197.208.0/2015.197.208.1 to 15.197.223.25415.197.223.2554,094
9515.197.224.0/2015.197.224.1 to 15.197.239.25415.197.239.2554,094
9615.197.240.0/2015.197.240.1 to 15.197.255.25415.197.255.2554,094
9715.198.0.0/2015.198.0.1 to 15.198.15.25415.198.15.2554,094
9815.198.16.0/2015.198.16.1 to 15.198.31.25415.198.31.2554,094
9915.198.32.0/2015.198.32.1 to 15.198.47.25415.198.47.2554,094
10015.198.48.0/2015.198.48.1 to 15.198.63.25415.198.63.2554,094
10115.198.64.0/2015.198.64.1 to 15.198.79.25415.198.79.2554,094
10215.198.80.0/2015.198.80.1 to 15.198.95.25415.198.95.2554,094
10315.198.96.0/2015.198.96.1 to 15.198.111.25415.198.111.2554,094
10415.198.112.0/2015.198.112.1 to 15.198.127.25415.198.127.2554,094
10515.198.128.0/2015.198.128.1 to 15.198.143.25415.198.143.2554,094
10615.198.144.0/2015.198.144.1 to 15.198.159.25415.198.159.2554,094
10715.198.160.0/2015.198.160.1 to 15.198.175.25415.198.175.2554,094
10815.198.176.0/2015.198.176.1 to 15.198.191.25415.198.191.2554,094
10915.198.192.0/2015.198.192.1 to 15.198.207.25415.198.207.2554,094
11015.198.208.0/2015.198.208.1 to 15.198.223.25415.198.223.2554,094
11115.198.224.0/2015.198.224.1 to 15.198.239.25415.198.239.2554,094
11215.198.240.0/2015.198.240.1 to 15.198.255.25415.198.255.2554,094
11315.199.0.0/2015.199.0.1 to 15.199.15.25415.199.15.2554,094
11415.199.16.0/2015.199.16.1 to 15.199.31.25415.199.31.2554,094
11515.199.32.0/2015.199.32.1 to 15.199.47.25415.199.47.2554,094
11615.199.48.0/2015.199.48.1 to 15.199.63.25415.199.63.2554,094
11715.199.64.0/2015.199.64.1 to 15.199.79.25415.199.79.2554,094
11815.199.80.0/2015.199.80.1 to 15.199.95.25415.199.95.2554,094
11915.199.96.0/2015.199.96.1 to 15.199.111.25415.199.111.2554,094
12015.199.112.0/2015.199.112.1 to 15.199.127.25415.199.127.2554,094
12115.199.128.0/2015.199.128.1 to 15.199.143.25415.199.143.2554,094
12215.199.144.0/2015.199.144.1 to 15.199.159.25415.199.159.2554,094
12315.199.160.0/2015.199.160.1 to 15.199.175.25415.199.175.2554,094
12415.199.176.0/2015.199.176.1 to 15.199.191.25415.199.191.2554,094
12515.199.192.0/2015.199.192.1 to 15.199.207.25415.199.207.2554,094
12615.199.208.0/2015.199.208.1 to 15.199.223.25415.199.223.2554,094
12715.199.224.0/2015.199.224.1 to 15.199.239.25415.199.239.2554,094
12815.199.240.0/2015.199.240.1 to 15.199.255.25415.199.255.2554,094
12915.200.0.0/2015.200.0.1 to 15.200.15.25415.200.15.2554,094
13015.200.16.0/2015.200.16.1 to 15.200.31.25415.200.31.2554,094
13115.200.32.0/2015.200.32.1 to 15.200.47.25415.200.47.2554,094
13215.200.48.0/2015.200.48.1 to 15.200.63.25415.200.63.2554,094
13315.200.64.0/2015.200.64.1 to 15.200.79.25415.200.79.2554,094
13415.200.80.0/2015.200.80.1 to 15.200.95.25415.200.95.2554,094
13515.200.96.0/2015.200.96.1 to 15.200.111.25415.200.111.2554,094
13615.200.112.0/2015.200.112.1 to 15.200.127.25415.200.127.2554,094
13715.200.128.0/2015.200.128.1 to 15.200.143.25415.200.143.2554,094
13815.200.144.0/2015.200.144.1 to 15.200.159.25415.200.159.2554,094
13915.200.160.0/2015.200.160.1 to 15.200.175.25415.200.175.2554,094
14015.200.176.0/2015.200.176.1 to 15.200.191.25415.200.191.2554,094
14115.200.192.0/2015.200.192.1 to 15.200.207.25415.200.207.2554,094
14215.200.208.0/2015.200.208.1 to 15.200.223.25415.200.223.2554,094
14315.200.224.0/2015.200.224.1 to 15.200.239.25415.200.239.2554,094
14415.200.240.0/2015.200.240.1 to 15.200.255.25415.200.255.2554,094
14515.201.0.0/2015.201.0.1 to 15.201.15.25415.201.15.2554,094
14615.201.16.0/2015.201.16.1 to 15.201.31.25415.201.31.2554,094
14715.201.32.0/2015.201.32.1 to 15.201.47.25415.201.47.2554,094
14815.201.48.0/2015.201.48.1 to 15.201.63.25415.201.63.2554,094
14915.201.64.0/2015.201.64.1 to 15.201.79.25415.201.79.2554,094
15015.201.80.0/2015.201.80.1 to 15.201.95.25415.201.95.2554,094
15115.201.96.0/2015.201.96.1 to 15.201.111.25415.201.111.2554,094
15215.201.112.0/2015.201.112.1 to 15.201.127.25415.201.127.2554,094
15315.201.128.0/2015.201.128.1 to 15.201.143.25415.201.143.2554,094
15415.201.144.0/2015.201.144.1 to 15.201.159.25415.201.159.2554,094
15515.201.160.0/2015.201.160.1 to 15.201.175.25415.201.175.2554,094
15615.201.176.0/2015.201.176.1 to 15.201.191.25415.201.191.2554,094
15715.201.192.0/2015.201.192.1 to 15.201.207.25415.201.207.2554,094
15815.201.208.0/2015.201.208.1 to 15.201.223.25415.201.223.2554,094
15915.201.224.0/2015.201.224.1 to 15.201.239.25415.201.239.2554,094
16015.201.240.0/2015.201.240.1 to 15.201.255.25415.201.255.2554,094
16115.202.0.0/2015.202.0.1 to 15.202.15.25415.202.15.2554,094
16215.202.16.0/2015.202.16.1 to 15.202.31.25415.202.31.2554,094
16315.202.32.0/2015.202.32.1 to 15.202.47.25415.202.47.2554,094
16415.202.48.0/2015.202.48.1 to 15.202.63.25415.202.63.2554,094
16515.202.64.0/2015.202.64.1 to 15.202.79.25415.202.79.2554,094
16615.202.80.0/2015.202.80.1 to 15.202.95.25415.202.95.2554,094
16715.202.96.0/2015.202.96.1 to 15.202.111.25415.202.111.2554,094
16815.202.112.0/2015.202.112.1 to 15.202.127.25415.202.127.2554,094
16915.202.128.0/2015.202.128.1 to 15.202.143.25415.202.143.2554,094
17015.202.144.0/2015.202.144.1 to 15.202.159.25415.202.159.2554,094
17115.202.160.0/2015.202.160.1 to 15.202.175.25415.202.175.2554,094
17215.202.176.0/2015.202.176.1 to 15.202.191.25415.202.191.2554,094
17315.202.192.0/2015.202.192.1 to 15.202.207.25415.202.207.2554,094
17415.202.208.0/2015.202.208.1 to 15.202.223.25415.202.223.2554,094
17515.202.224.0/2015.202.224.1 to 15.202.239.25415.202.239.2554,094
17615.202.240.0/2015.202.240.1 to 15.202.255.25415.202.255.2554,094
17715.203.0.0/2015.203.0.1 to 15.203.15.25415.203.15.2554,094
17815.203.16.0/2015.203.16.1 to 15.203.31.25415.203.31.2554,094
17915.203.32.0/2015.203.32.1 to 15.203.47.25415.203.47.2554,094
18015.203.48.0/2015.203.48.1 to 15.203.63.25415.203.63.2554,094
18115.203.64.0/2015.203.64.1 to 15.203.79.25415.203.79.2554,094
18215.203.80.0/2015.203.80.1 to 15.203.95.25415.203.95.2554,094
18315.203.96.0/2015.203.96.1 to 15.203.111.25415.203.111.2554,094
18415.203.112.0/2015.203.112.1 to 15.203.127.25415.203.127.2554,094
18515.203.128.0/2015.203.128.1 to 15.203.143.25415.203.143.2554,094
18615.203.144.0/2015.203.144.1 to 15.203.159.25415.203.159.2554,094
18715.203.160.0/2015.203.160.1 to 15.203.175.25415.203.175.2554,094
18815.203.176.0/2015.203.176.1 to 15.203.191.25415.203.191.2554,094
18915.203.192.0/2015.203.192.1 to 15.203.207.25415.203.207.2554,094
19015.203.208.0/2015.203.208.1 to 15.203.223.25415.203.223.2554,094
19115.203.224.0/2015.203.224.1 to 15.203.239.25415.203.239.2554,094
19215.203.240.0/2015.203.240.1 to 15.203.255.25415.203.255.2554,094
19315.204.0.0/2015.204.0.1 to 15.204.15.25415.204.15.2554,094
19415.204.16.0/2015.204.16.1 to 15.204.31.25415.204.31.2554,094
19515.204.32.0/2015.204.32.1 to 15.204.47.25415.204.47.2554,094
19615.204.48.0/2015.204.48.1 to 15.204.63.25415.204.63.2554,094
19715.204.64.0/2015.204.64.1 to 15.204.79.25415.204.79.2554,094
19815.204.80.0/2015.204.80.1 to 15.204.95.25415.204.95.2554,094
19915.204.96.0/2015.204.96.1 to 15.204.111.25415.204.111.2554,094
20015.204.112.0/2015.204.112.1 to 15.204.127.25415.204.127.2554,094
20115.204.128.0/2015.204.128.1 to 15.204.143.25415.204.143.2554,094
20215.204.144.0/2015.204.144.1 to 15.204.159.25415.204.159.2554,094
20315.204.160.0/2015.204.160.1 to 15.204.175.25415.204.175.2554,094
20415.204.176.0/2015.204.176.1 to 15.204.191.25415.204.191.2554,094
20515.204.192.0/2015.204.192.1 to 15.204.207.25415.204.207.2554,094
20615.204.208.0/2015.204.208.1 to 15.204.223.25415.204.223.2554,094
20715.204.224.0/2015.204.224.1 to 15.204.239.25415.204.239.2554,094
20815.204.240.0/2015.204.240.1 to 15.204.255.25415.204.255.2554,094
20915.205.0.0/2015.205.0.1 to 15.205.15.25415.205.15.2554,094
21015.205.16.0/2015.205.16.1 to 15.205.31.25415.205.31.2554,094
21115.205.32.0/2015.205.32.1 to 15.205.47.25415.205.47.2554,094
21215.205.48.0/2015.205.48.1 to 15.205.63.25415.205.63.2554,094
21315.205.64.0/2015.205.64.1 to 15.205.79.25415.205.79.2554,094
21415.205.80.0/2015.205.80.1 to 15.205.95.25415.205.95.2554,094
21515.205.96.0/2015.205.96.1 to 15.205.111.25415.205.111.2554,094
21615.205.112.0/2015.205.112.1 to 15.205.127.25415.205.127.2554,094
21715.205.128.0/2015.205.128.1 to 15.205.143.25415.205.143.2554,094
21815.205.144.0/2015.205.144.1 to 15.205.159.25415.205.159.2554,094
21915.205.160.0/2015.205.160.1 to 15.205.175.25415.205.175.2554,094
22015.205.176.0/2015.205.176.1 to 15.205.191.25415.205.191.2554,094
22115.205.192.0/2015.205.192.1 to 15.205.207.25415.205.207.2554,094
22215.205.208.0/2015.205.208.1 to 15.205.223.25415.205.223.2554,094
22315.205.224.0/2015.205.224.1 to 15.205.239.25415.205.239.2554,094
22415.205.240.0/2015.205.240.1 to 15.205.255.25415.205.255.2554,094
22515.206.0.0/2015.206.0.1 to 15.206.15.25415.206.15.2554,094
22615.206.16.0/2015.206.16.1 to 15.206.31.25415.206.31.2554,094
22715.206.32.0/2015.206.32.1 to 15.206.47.25415.206.47.2554,094
22815.206.48.0/2015.206.48.1 to 15.206.63.25415.206.63.2554,094
22915.206.64.0/2015.206.64.1 to 15.206.79.25415.206.79.2554,094
23015.206.80.0/2015.206.80.1 to 15.206.95.25415.206.95.2554,094
23115.206.96.0/2015.206.96.1 to 15.206.111.25415.206.111.2554,094
23215.206.112.0/2015.206.112.1 to 15.206.127.25415.206.127.2554,094
23315.206.128.0/2015.206.128.1 to 15.206.143.25415.206.143.2554,094
23415.206.144.0/2015.206.144.1 to 15.206.159.25415.206.159.2554,094
23515.206.160.0/2015.206.160.1 to 15.206.175.25415.206.175.2554,094
23615.206.176.0/2015.206.176.1 to 15.206.191.25415.206.191.2554,094
23715.206.192.0/2015.206.192.1 to 15.206.207.25415.206.207.2554,094
23815.206.208.0/2015.206.208.1 to 15.206.223.25415.206.223.2554,094
23915.206.224.0/2015.206.224.1 to 15.206.239.25415.206.239.2554,094
24015.206.240.0/2015.206.240.1 to 15.206.255.25415.206.255.2554,094
24115.207.0.0/2015.207.0.1 to 15.207.15.25415.207.15.2554,094
24215.207.16.0/2015.207.16.1 to 15.207.31.25415.207.31.2554,094
24315.207.32.0/2015.207.32.1 to 15.207.47.25415.207.47.2554,094
24415.207.48.0/2015.207.48.1 to 15.207.63.25415.207.63.2554,094
24515.207.64.0/2015.207.64.1 to 15.207.79.25415.207.79.2554,094
24615.207.80.0/2015.207.80.1 to 15.207.95.25415.207.95.2554,094
24715.207.96.0/2015.207.96.1 to 15.207.111.25415.207.111.2554,094
24815.207.112.0/2015.207.112.1 to 15.207.127.25415.207.127.2554,094
24915.207.128.0/2015.207.128.1 to 15.207.143.25415.207.143.2554,094
25015.207.144.0/2015.207.144.1 to 15.207.159.25415.207.159.2554,094
25115.207.160.0/2015.207.160.1 to 15.207.175.25415.207.175.2554,094
25215.207.176.0/2015.207.176.1 to 15.207.191.25415.207.191.2554,094
25315.207.192.0/2015.207.192.1 to 15.207.207.25415.207.207.2554,094
25415.207.208.0/2015.207.208.1 to 15.207.223.25415.207.223.2554,094
25515.207.224.0/2015.207.224.1 to 15.207.239.25415.207.239.2554,094
25615.207.240.0/2015.207.240.1 to 15.207.255.25415.207.255.2554,094

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.