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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/21
/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 512 subnets of /21; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
115.192.0.0/2115.192.0.1 to 15.192.7.25415.192.7.2552,046
215.192.8.0/2115.192.8.1 to 15.192.15.25415.192.15.2552,046
315.192.16.0/2115.192.16.1 to 15.192.23.25415.192.23.2552,046
415.192.24.0/2115.192.24.1 to 15.192.31.25415.192.31.2552,046
515.192.32.0/2115.192.32.1 to 15.192.39.25415.192.39.2552,046
615.192.40.0/2115.192.40.1 to 15.192.47.25415.192.47.2552,046
715.192.48.0/2115.192.48.1 to 15.192.55.25415.192.55.2552,046
815.192.56.0/2115.192.56.1 to 15.192.63.25415.192.63.2552,046
915.192.64.0/2115.192.64.1 to 15.192.71.25415.192.71.2552,046
1015.192.72.0/2115.192.72.1 to 15.192.79.25415.192.79.2552,046
1115.192.80.0/2115.192.80.1 to 15.192.87.25415.192.87.2552,046
1215.192.88.0/2115.192.88.1 to 15.192.95.25415.192.95.2552,046
1315.192.96.0/2115.192.96.1 to 15.192.103.25415.192.103.2552,046
1415.192.104.0/2115.192.104.1 to 15.192.111.25415.192.111.2552,046
1515.192.112.0/2115.192.112.1 to 15.192.119.25415.192.119.2552,046
1615.192.120.0/2115.192.120.1 to 15.192.127.25415.192.127.2552,046
1715.192.128.0/2115.192.128.1 to 15.192.135.25415.192.135.2552,046
1815.192.136.0/2115.192.136.1 to 15.192.143.25415.192.143.2552,046
1915.192.144.0/2115.192.144.1 to 15.192.151.25415.192.151.2552,046
2015.192.152.0/2115.192.152.1 to 15.192.159.25415.192.159.2552,046
2115.192.160.0/2115.192.160.1 to 15.192.167.25415.192.167.2552,046
2215.192.168.0/2115.192.168.1 to 15.192.175.25415.192.175.2552,046
2315.192.176.0/2115.192.176.1 to 15.192.183.25415.192.183.2552,046
2415.192.184.0/2115.192.184.1 to 15.192.191.25415.192.191.2552,046
2515.192.192.0/2115.192.192.1 to 15.192.199.25415.192.199.2552,046
2615.192.200.0/2115.192.200.1 to 15.192.207.25415.192.207.2552,046
2715.192.208.0/2115.192.208.1 to 15.192.215.25415.192.215.2552,046
2815.192.216.0/2115.192.216.1 to 15.192.223.25415.192.223.2552,046
2915.192.224.0/2115.192.224.1 to 15.192.231.25415.192.231.2552,046
3015.192.232.0/2115.192.232.1 to 15.192.239.25415.192.239.2552,046
3115.192.240.0/2115.192.240.1 to 15.192.247.25415.192.247.2552,046
3215.192.248.0/2115.192.248.1 to 15.192.255.25415.192.255.2552,046
3315.193.0.0/2115.193.0.1 to 15.193.7.25415.193.7.2552,046
3415.193.8.0/2115.193.8.1 to 15.193.15.25415.193.15.2552,046
3515.193.16.0/2115.193.16.1 to 15.193.23.25415.193.23.2552,046
3615.193.24.0/2115.193.24.1 to 15.193.31.25415.193.31.2552,046
3715.193.32.0/2115.193.32.1 to 15.193.39.25415.193.39.2552,046
3815.193.40.0/2115.193.40.1 to 15.193.47.25415.193.47.2552,046
3915.193.48.0/2115.193.48.1 to 15.193.55.25415.193.55.2552,046
4015.193.56.0/2115.193.56.1 to 15.193.63.25415.193.63.2552,046
4115.193.64.0/2115.193.64.1 to 15.193.71.25415.193.71.2552,046
4215.193.72.0/2115.193.72.1 to 15.193.79.25415.193.79.2552,046
4315.193.80.0/2115.193.80.1 to 15.193.87.25415.193.87.2552,046
4415.193.88.0/2115.193.88.1 to 15.193.95.25415.193.95.2552,046
4515.193.96.0/2115.193.96.1 to 15.193.103.25415.193.103.2552,046
4615.193.104.0/2115.193.104.1 to 15.193.111.25415.193.111.2552,046
4715.193.112.0/2115.193.112.1 to 15.193.119.25415.193.119.2552,046
4815.193.120.0/2115.193.120.1 to 15.193.127.25415.193.127.2552,046
4915.193.128.0/2115.193.128.1 to 15.193.135.25415.193.135.2552,046
5015.193.136.0/2115.193.136.1 to 15.193.143.25415.193.143.2552,046
5115.193.144.0/2115.193.144.1 to 15.193.151.25415.193.151.2552,046
5215.193.152.0/2115.193.152.1 to 15.193.159.25415.193.159.2552,046
5315.193.160.0/2115.193.160.1 to 15.193.167.25415.193.167.2552,046
5415.193.168.0/2115.193.168.1 to 15.193.175.25415.193.175.2552,046
5515.193.176.0/2115.193.176.1 to 15.193.183.25415.193.183.2552,046
5615.193.184.0/2115.193.184.1 to 15.193.191.25415.193.191.2552,046
5715.193.192.0/2115.193.192.1 to 15.193.199.25415.193.199.2552,046
5815.193.200.0/2115.193.200.1 to 15.193.207.25415.193.207.2552,046
5915.193.208.0/2115.193.208.1 to 15.193.215.25415.193.215.2552,046
6015.193.216.0/2115.193.216.1 to 15.193.223.25415.193.223.2552,046
6115.193.224.0/2115.193.224.1 to 15.193.231.25415.193.231.2552,046
6215.193.232.0/2115.193.232.1 to 15.193.239.25415.193.239.2552,046
6315.193.240.0/2115.193.240.1 to 15.193.247.25415.193.247.2552,046
6415.193.248.0/2115.193.248.1 to 15.193.255.25415.193.255.2552,046
6515.194.0.0/2115.194.0.1 to 15.194.7.25415.194.7.2552,046
6615.194.8.0/2115.194.8.1 to 15.194.15.25415.194.15.2552,046
6715.194.16.0/2115.194.16.1 to 15.194.23.25415.194.23.2552,046
6815.194.24.0/2115.194.24.1 to 15.194.31.25415.194.31.2552,046
6915.194.32.0/2115.194.32.1 to 15.194.39.25415.194.39.2552,046
7015.194.40.0/2115.194.40.1 to 15.194.47.25415.194.47.2552,046
7115.194.48.0/2115.194.48.1 to 15.194.55.25415.194.55.2552,046
7215.194.56.0/2115.194.56.1 to 15.194.63.25415.194.63.2552,046
7315.194.64.0/2115.194.64.1 to 15.194.71.25415.194.71.2552,046
7415.194.72.0/2115.194.72.1 to 15.194.79.25415.194.79.2552,046
7515.194.80.0/2115.194.80.1 to 15.194.87.25415.194.87.2552,046
7615.194.88.0/2115.194.88.1 to 15.194.95.25415.194.95.2552,046
7715.194.96.0/2115.194.96.1 to 15.194.103.25415.194.103.2552,046
7815.194.104.0/2115.194.104.1 to 15.194.111.25415.194.111.2552,046
7915.194.112.0/2115.194.112.1 to 15.194.119.25415.194.119.2552,046
8015.194.120.0/2115.194.120.1 to 15.194.127.25415.194.127.2552,046
8115.194.128.0/2115.194.128.1 to 15.194.135.25415.194.135.2552,046
8215.194.136.0/2115.194.136.1 to 15.194.143.25415.194.143.2552,046
8315.194.144.0/2115.194.144.1 to 15.194.151.25415.194.151.2552,046
8415.194.152.0/2115.194.152.1 to 15.194.159.25415.194.159.2552,046
8515.194.160.0/2115.194.160.1 to 15.194.167.25415.194.167.2552,046
8615.194.168.0/2115.194.168.1 to 15.194.175.25415.194.175.2552,046
8715.194.176.0/2115.194.176.1 to 15.194.183.25415.194.183.2552,046
8815.194.184.0/2115.194.184.1 to 15.194.191.25415.194.191.2552,046
8915.194.192.0/2115.194.192.1 to 15.194.199.25415.194.199.2552,046
9015.194.200.0/2115.194.200.1 to 15.194.207.25415.194.207.2552,046
9115.194.208.0/2115.194.208.1 to 15.194.215.25415.194.215.2552,046
9215.194.216.0/2115.194.216.1 to 15.194.223.25415.194.223.2552,046
9315.194.224.0/2115.194.224.1 to 15.194.231.25415.194.231.2552,046
9415.194.232.0/2115.194.232.1 to 15.194.239.25415.194.239.2552,046
9515.194.240.0/2115.194.240.1 to 15.194.247.25415.194.247.2552,046
9615.194.248.0/2115.194.248.1 to 15.194.255.25415.194.255.2552,046
9715.195.0.0/2115.195.0.1 to 15.195.7.25415.195.7.2552,046
9815.195.8.0/2115.195.8.1 to 15.195.15.25415.195.15.2552,046
9915.195.16.0/2115.195.16.1 to 15.195.23.25415.195.23.2552,046
10015.195.24.0/2115.195.24.1 to 15.195.31.25415.195.31.2552,046
10115.195.32.0/2115.195.32.1 to 15.195.39.25415.195.39.2552,046
10215.195.40.0/2115.195.40.1 to 15.195.47.25415.195.47.2552,046
10315.195.48.0/2115.195.48.1 to 15.195.55.25415.195.55.2552,046
10415.195.56.0/2115.195.56.1 to 15.195.63.25415.195.63.2552,046
10515.195.64.0/2115.195.64.1 to 15.195.71.25415.195.71.2552,046
10615.195.72.0/2115.195.72.1 to 15.195.79.25415.195.79.2552,046
10715.195.80.0/2115.195.80.1 to 15.195.87.25415.195.87.2552,046
10815.195.88.0/2115.195.88.1 to 15.195.95.25415.195.95.2552,046
10915.195.96.0/2115.195.96.1 to 15.195.103.25415.195.103.2552,046
11015.195.104.0/2115.195.104.1 to 15.195.111.25415.195.111.2552,046
11115.195.112.0/2115.195.112.1 to 15.195.119.25415.195.119.2552,046
11215.195.120.0/2115.195.120.1 to 15.195.127.25415.195.127.2552,046
11315.195.128.0/2115.195.128.1 to 15.195.135.25415.195.135.2552,046
11415.195.136.0/2115.195.136.1 to 15.195.143.25415.195.143.2552,046
11515.195.144.0/2115.195.144.1 to 15.195.151.25415.195.151.2552,046
11615.195.152.0/2115.195.152.1 to 15.195.159.25415.195.159.2552,046
11715.195.160.0/2115.195.160.1 to 15.195.167.25415.195.167.2552,046
11815.195.168.0/2115.195.168.1 to 15.195.175.25415.195.175.2552,046
11915.195.176.0/2115.195.176.1 to 15.195.183.25415.195.183.2552,046
12015.195.184.0/2115.195.184.1 to 15.195.191.25415.195.191.2552,046
12115.195.192.0/2115.195.192.1 to 15.195.199.25415.195.199.2552,046
12215.195.200.0/2115.195.200.1 to 15.195.207.25415.195.207.2552,046
12315.195.208.0/2115.195.208.1 to 15.195.215.25415.195.215.2552,046
12415.195.216.0/2115.195.216.1 to 15.195.223.25415.195.223.2552,046
12515.195.224.0/2115.195.224.1 to 15.195.231.25415.195.231.2552,046
12615.195.232.0/2115.195.232.1 to 15.195.239.25415.195.239.2552,046
12715.195.240.0/2115.195.240.1 to 15.195.247.25415.195.247.2552,046
12815.195.248.0/2115.195.248.1 to 15.195.255.25415.195.255.2552,046
12915.196.0.0/2115.196.0.1 to 15.196.7.25415.196.7.2552,046
13015.196.8.0/2115.196.8.1 to 15.196.15.25415.196.15.2552,046
13115.196.16.0/2115.196.16.1 to 15.196.23.25415.196.23.2552,046
13215.196.24.0/2115.196.24.1 to 15.196.31.25415.196.31.2552,046
13315.196.32.0/2115.196.32.1 to 15.196.39.25415.196.39.2552,046
13415.196.40.0/2115.196.40.1 to 15.196.47.25415.196.47.2552,046
13515.196.48.0/2115.196.48.1 to 15.196.55.25415.196.55.2552,046
13615.196.56.0/2115.196.56.1 to 15.196.63.25415.196.63.2552,046
13715.196.64.0/2115.196.64.1 to 15.196.71.25415.196.71.2552,046
13815.196.72.0/2115.196.72.1 to 15.196.79.25415.196.79.2552,046
13915.196.80.0/2115.196.80.1 to 15.196.87.25415.196.87.2552,046
14015.196.88.0/2115.196.88.1 to 15.196.95.25415.196.95.2552,046
14115.196.96.0/2115.196.96.1 to 15.196.103.25415.196.103.2552,046
14215.196.104.0/2115.196.104.1 to 15.196.111.25415.196.111.2552,046
14315.196.112.0/2115.196.112.1 to 15.196.119.25415.196.119.2552,046
14415.196.120.0/2115.196.120.1 to 15.196.127.25415.196.127.2552,046
14515.196.128.0/2115.196.128.1 to 15.196.135.25415.196.135.2552,046
14615.196.136.0/2115.196.136.1 to 15.196.143.25415.196.143.2552,046
14715.196.144.0/2115.196.144.1 to 15.196.151.25415.196.151.2552,046
14815.196.152.0/2115.196.152.1 to 15.196.159.25415.196.159.2552,046
14915.196.160.0/2115.196.160.1 to 15.196.167.25415.196.167.2552,046
15015.196.168.0/2115.196.168.1 to 15.196.175.25415.196.175.2552,046
15115.196.176.0/2115.196.176.1 to 15.196.183.25415.196.183.2552,046
15215.196.184.0/2115.196.184.1 to 15.196.191.25415.196.191.2552,046
15315.196.192.0/2115.196.192.1 to 15.196.199.25415.196.199.2552,046
15415.196.200.0/2115.196.200.1 to 15.196.207.25415.196.207.2552,046
15515.196.208.0/2115.196.208.1 to 15.196.215.25415.196.215.2552,046
15615.196.216.0/2115.196.216.1 to 15.196.223.25415.196.223.2552,046
15715.196.224.0/2115.196.224.1 to 15.196.231.25415.196.231.2552,046
15815.196.232.0/2115.196.232.1 to 15.196.239.25415.196.239.2552,046
15915.196.240.0/2115.196.240.1 to 15.196.247.25415.196.247.2552,046
16015.196.248.0/2115.196.248.1 to 15.196.255.25415.196.255.2552,046
16115.197.0.0/2115.197.0.1 to 15.197.7.25415.197.7.2552,046
16215.197.8.0/2115.197.8.1 to 15.197.15.25415.197.15.2552,046
16315.197.16.0/2115.197.16.1 to 15.197.23.25415.197.23.2552,046
16415.197.24.0/2115.197.24.1 to 15.197.31.25415.197.31.2552,046
16515.197.32.0/2115.197.32.1 to 15.197.39.25415.197.39.2552,046
16615.197.40.0/2115.197.40.1 to 15.197.47.25415.197.47.2552,046
16715.197.48.0/2115.197.48.1 to 15.197.55.25415.197.55.2552,046
16815.197.56.0/2115.197.56.1 to 15.197.63.25415.197.63.2552,046
16915.197.64.0/2115.197.64.1 to 15.197.71.25415.197.71.2552,046
17015.197.72.0/2115.197.72.1 to 15.197.79.25415.197.79.2552,046
17115.197.80.0/2115.197.80.1 to 15.197.87.25415.197.87.2552,046
17215.197.88.0/2115.197.88.1 to 15.197.95.25415.197.95.2552,046
17315.197.96.0/2115.197.96.1 to 15.197.103.25415.197.103.2552,046
17415.197.104.0/2115.197.104.1 to 15.197.111.25415.197.111.2552,046
17515.197.112.0/2115.197.112.1 to 15.197.119.25415.197.119.2552,046
17615.197.120.0/2115.197.120.1 to 15.197.127.25415.197.127.2552,046
17715.197.128.0/2115.197.128.1 to 15.197.135.25415.197.135.2552,046
17815.197.136.0/2115.197.136.1 to 15.197.143.25415.197.143.2552,046
17915.197.144.0/2115.197.144.1 to 15.197.151.25415.197.151.2552,046
18015.197.152.0/2115.197.152.1 to 15.197.159.25415.197.159.2552,046
18115.197.160.0/2115.197.160.1 to 15.197.167.25415.197.167.2552,046
18215.197.168.0/2115.197.168.1 to 15.197.175.25415.197.175.2552,046
18315.197.176.0/2115.197.176.1 to 15.197.183.25415.197.183.2552,046
18415.197.184.0/2115.197.184.1 to 15.197.191.25415.197.191.2552,046
18515.197.192.0/2115.197.192.1 to 15.197.199.25415.197.199.2552,046
18615.197.200.0/2115.197.200.1 to 15.197.207.25415.197.207.2552,046
18715.197.208.0/2115.197.208.1 to 15.197.215.25415.197.215.2552,046
18815.197.216.0/2115.197.216.1 to 15.197.223.25415.197.223.2552,046
18915.197.224.0/2115.197.224.1 to 15.197.231.25415.197.231.2552,046
19015.197.232.0/2115.197.232.1 to 15.197.239.25415.197.239.2552,046
19115.197.240.0/2115.197.240.1 to 15.197.247.25415.197.247.2552,046
19215.197.248.0/2115.197.248.1 to 15.197.255.25415.197.255.2552,046
19315.198.0.0/2115.198.0.1 to 15.198.7.25415.198.7.2552,046
19415.198.8.0/2115.198.8.1 to 15.198.15.25415.198.15.2552,046
19515.198.16.0/2115.198.16.1 to 15.198.23.25415.198.23.2552,046
19615.198.24.0/2115.198.24.1 to 15.198.31.25415.198.31.2552,046
19715.198.32.0/2115.198.32.1 to 15.198.39.25415.198.39.2552,046
19815.198.40.0/2115.198.40.1 to 15.198.47.25415.198.47.2552,046
19915.198.48.0/2115.198.48.1 to 15.198.55.25415.198.55.2552,046
20015.198.56.0/2115.198.56.1 to 15.198.63.25415.198.63.2552,046
20115.198.64.0/2115.198.64.1 to 15.198.71.25415.198.71.2552,046
20215.198.72.0/2115.198.72.1 to 15.198.79.25415.198.79.2552,046
20315.198.80.0/2115.198.80.1 to 15.198.87.25415.198.87.2552,046
20415.198.88.0/2115.198.88.1 to 15.198.95.25415.198.95.2552,046
20515.198.96.0/2115.198.96.1 to 15.198.103.25415.198.103.2552,046
20615.198.104.0/2115.198.104.1 to 15.198.111.25415.198.111.2552,046
20715.198.112.0/2115.198.112.1 to 15.198.119.25415.198.119.2552,046
20815.198.120.0/2115.198.120.1 to 15.198.127.25415.198.127.2552,046
20915.198.128.0/2115.198.128.1 to 15.198.135.25415.198.135.2552,046
21015.198.136.0/2115.198.136.1 to 15.198.143.25415.198.143.2552,046
21115.198.144.0/2115.198.144.1 to 15.198.151.25415.198.151.2552,046
21215.198.152.0/2115.198.152.1 to 15.198.159.25415.198.159.2552,046
21315.198.160.0/2115.198.160.1 to 15.198.167.25415.198.167.2552,046
21415.198.168.0/2115.198.168.1 to 15.198.175.25415.198.175.2552,046
21515.198.176.0/2115.198.176.1 to 15.198.183.25415.198.183.2552,046
21615.198.184.0/2115.198.184.1 to 15.198.191.25415.198.191.2552,046
21715.198.192.0/2115.198.192.1 to 15.198.199.25415.198.199.2552,046
21815.198.200.0/2115.198.200.1 to 15.198.207.25415.198.207.2552,046
21915.198.208.0/2115.198.208.1 to 15.198.215.25415.198.215.2552,046
22015.198.216.0/2115.198.216.1 to 15.198.223.25415.198.223.2552,046
22115.198.224.0/2115.198.224.1 to 15.198.231.25415.198.231.2552,046
22215.198.232.0/2115.198.232.1 to 15.198.239.25415.198.239.2552,046
22315.198.240.0/2115.198.240.1 to 15.198.247.25415.198.247.2552,046
22415.198.248.0/2115.198.248.1 to 15.198.255.25415.198.255.2552,046
22515.199.0.0/2115.199.0.1 to 15.199.7.25415.199.7.2552,046
22615.199.8.0/2115.199.8.1 to 15.199.15.25415.199.15.2552,046
22715.199.16.0/2115.199.16.1 to 15.199.23.25415.199.23.2552,046
22815.199.24.0/2115.199.24.1 to 15.199.31.25415.199.31.2552,046
22915.199.32.0/2115.199.32.1 to 15.199.39.25415.199.39.2552,046
23015.199.40.0/2115.199.40.1 to 15.199.47.25415.199.47.2552,046
23115.199.48.0/2115.199.48.1 to 15.199.55.25415.199.55.2552,046
23215.199.56.0/2115.199.56.1 to 15.199.63.25415.199.63.2552,046
23315.199.64.0/2115.199.64.1 to 15.199.71.25415.199.71.2552,046
23415.199.72.0/2115.199.72.1 to 15.199.79.25415.199.79.2552,046
23515.199.80.0/2115.199.80.1 to 15.199.87.25415.199.87.2552,046
23615.199.88.0/2115.199.88.1 to 15.199.95.25415.199.95.2552,046
23715.199.96.0/2115.199.96.1 to 15.199.103.25415.199.103.2552,046
23815.199.104.0/2115.199.104.1 to 15.199.111.25415.199.111.2552,046
23915.199.112.0/2115.199.112.1 to 15.199.119.25415.199.119.2552,046
24015.199.120.0/2115.199.120.1 to 15.199.127.25415.199.127.2552,046
24115.199.128.0/2115.199.128.1 to 15.199.135.25415.199.135.2552,046
24215.199.136.0/2115.199.136.1 to 15.199.143.25415.199.143.2552,046
24315.199.144.0/2115.199.144.1 to 15.199.151.25415.199.151.2552,046
24415.199.152.0/2115.199.152.1 to 15.199.159.25415.199.159.2552,046
24515.199.160.0/2115.199.160.1 to 15.199.167.25415.199.167.2552,046
24615.199.168.0/2115.199.168.1 to 15.199.175.25415.199.175.2552,046
24715.199.176.0/2115.199.176.1 to 15.199.183.25415.199.183.2552,046
24815.199.184.0/2115.199.184.1 to 15.199.191.25415.199.191.2552,046
24915.199.192.0/2115.199.192.1 to 15.199.199.25415.199.199.2552,046
25015.199.200.0/2115.199.200.1 to 15.199.207.25415.199.207.2552,046
25115.199.208.0/2115.199.208.1 to 15.199.215.25415.199.215.2552,046
25215.199.216.0/2115.199.216.1 to 15.199.223.25415.199.223.2552,046
25315.199.224.0/2115.199.224.1 to 15.199.231.25415.199.231.2552,046
25415.199.232.0/2115.199.232.1 to 15.199.239.25415.199.239.2552,046
25515.199.240.0/2115.199.240.1 to 15.199.247.25415.199.247.2552,046
25615.199.248.0/2115.199.248.1 to 15.199.255.25415.199.255.2552,046

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.