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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.

Network45.0.0.0/9
Usable hosts8,388,606
Subnet mask255.128.0.0
Addresses8,388,608
Network address
45.0.0.0
Broadcast address
45.127.255.255
First usable
45.0.0.1
Last usable
45.127.255.254
Usable hosts
8,388,606 (8,388,608 less the network and broadcast addresses)
Subnet mask
255.128.0.0
Wildcard mask
0.127.255.255 (Cisco ACLs, OSPF)
Prefix length
/9
Type
Public public
Old class
A (default /8)
As numbers
Hex 2D000000 · Integer 754974720 to 763363327
Reverse DNS zones
0.45.in-addr.arpa
1.45.in-addr.arpa
2.45.in-addr.arpa
3.45.in-addr.arpa
4.45.in-addr.arpa
5.45.in-addr.arpa
6.45.in-addr.arpa
7.45.in-addr.arpa
8.45.in-addr.arpa
9.45.in-addr.arpa
10.45.in-addr.arpa
11.45.in-addr.arpa
12.45.in-addr.arpa
13.45.in-addr.arpa
14.45.in-addr.arpa
15.45.in-addr.arpa
and 112 more
/9 is not on a 8-bit boundary, so it takes 128 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00101101.00000000.00000000.0000000045.0.0.0
Subnet mask11111111.10000000.00000000.00000000255.128.0.0
Network00101101.00000000.00000000.0000000045.0.0.0
Broadcast00101101.01111111.11111111.1111111145.127.255.255
Split into smaller subnets/21
/10 (2)/11 (4)/12 (8)/13 (16)/14 (32)/15 (64)/16 (128)/17 (256)/18 (512)/19 (1,024)/20 (2,048)/21 (4,096)

45.0.0.0/9 makes 4,096 subnets of /21; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
145.0.0.0/2145.0.0.1 to 45.0.7.25445.0.7.2552,046
245.0.8.0/2145.0.8.1 to 45.0.15.25445.0.15.2552,046
345.0.16.0/2145.0.16.1 to 45.0.23.25445.0.23.2552,046
445.0.24.0/2145.0.24.1 to 45.0.31.25445.0.31.2552,046
545.0.32.0/2145.0.32.1 to 45.0.39.25445.0.39.2552,046
645.0.40.0/2145.0.40.1 to 45.0.47.25445.0.47.2552,046
745.0.48.0/2145.0.48.1 to 45.0.55.25445.0.55.2552,046
845.0.56.0/2145.0.56.1 to 45.0.63.25445.0.63.2552,046
945.0.64.0/2145.0.64.1 to 45.0.71.25445.0.71.2552,046
1045.0.72.0/2145.0.72.1 to 45.0.79.25445.0.79.2552,046
1145.0.80.0/2145.0.80.1 to 45.0.87.25445.0.87.2552,046
1245.0.88.0/2145.0.88.1 to 45.0.95.25445.0.95.2552,046
1345.0.96.0/2145.0.96.1 to 45.0.103.25445.0.103.2552,046
1445.0.104.0/2145.0.104.1 to 45.0.111.25445.0.111.2552,046
1545.0.112.0/2145.0.112.1 to 45.0.119.25445.0.119.2552,046
1645.0.120.0/2145.0.120.1 to 45.0.127.25445.0.127.2552,046
1745.0.128.0/2145.0.128.1 to 45.0.135.25445.0.135.2552,046
1845.0.136.0/2145.0.136.1 to 45.0.143.25445.0.143.2552,046
1945.0.144.0/2145.0.144.1 to 45.0.151.25445.0.151.2552,046
2045.0.152.0/2145.0.152.1 to 45.0.159.25445.0.159.2552,046
2145.0.160.0/2145.0.160.1 to 45.0.167.25445.0.167.2552,046
2245.0.168.0/2145.0.168.1 to 45.0.175.25445.0.175.2552,046
2345.0.176.0/2145.0.176.1 to 45.0.183.25445.0.183.2552,046
2445.0.184.0/2145.0.184.1 to 45.0.191.25445.0.191.2552,046
2545.0.192.0/2145.0.192.1 to 45.0.199.25445.0.199.2552,046
2645.0.200.0/2145.0.200.1 to 45.0.207.25445.0.207.2552,046
2745.0.208.0/2145.0.208.1 to 45.0.215.25445.0.215.2552,046
2845.0.216.0/2145.0.216.1 to 45.0.223.25445.0.223.2552,046
2945.0.224.0/2145.0.224.1 to 45.0.231.25445.0.231.2552,046
3045.0.232.0/2145.0.232.1 to 45.0.239.25445.0.239.2552,046
3145.0.240.0/2145.0.240.1 to 45.0.247.25445.0.247.2552,046
3245.0.248.0/2145.0.248.1 to 45.0.255.25445.0.255.2552,046
3345.1.0.0/2145.1.0.1 to 45.1.7.25445.1.7.2552,046
3445.1.8.0/2145.1.8.1 to 45.1.15.25445.1.15.2552,046
3545.1.16.0/2145.1.16.1 to 45.1.23.25445.1.23.2552,046
3645.1.24.0/2145.1.24.1 to 45.1.31.25445.1.31.2552,046
3745.1.32.0/2145.1.32.1 to 45.1.39.25445.1.39.2552,046
3845.1.40.0/2145.1.40.1 to 45.1.47.25445.1.47.2552,046
3945.1.48.0/2145.1.48.1 to 45.1.55.25445.1.55.2552,046
4045.1.56.0/2145.1.56.1 to 45.1.63.25445.1.63.2552,046
4145.1.64.0/2145.1.64.1 to 45.1.71.25445.1.71.2552,046
4245.1.72.0/2145.1.72.1 to 45.1.79.25445.1.79.2552,046
4345.1.80.0/2145.1.80.1 to 45.1.87.25445.1.87.2552,046
4445.1.88.0/2145.1.88.1 to 45.1.95.25445.1.95.2552,046
4545.1.96.0/2145.1.96.1 to 45.1.103.25445.1.103.2552,046
4645.1.104.0/2145.1.104.1 to 45.1.111.25445.1.111.2552,046
4745.1.112.0/2145.1.112.1 to 45.1.119.25445.1.119.2552,046
4845.1.120.0/2145.1.120.1 to 45.1.127.25445.1.127.2552,046
4945.1.128.0/2145.1.128.1 to 45.1.135.25445.1.135.2552,046
5045.1.136.0/2145.1.136.1 to 45.1.143.25445.1.143.2552,046
5145.1.144.0/2145.1.144.1 to 45.1.151.25445.1.151.2552,046
5245.1.152.0/2145.1.152.1 to 45.1.159.25445.1.159.2552,046
5345.1.160.0/2145.1.160.1 to 45.1.167.25445.1.167.2552,046
5445.1.168.0/2145.1.168.1 to 45.1.175.25445.1.175.2552,046
5545.1.176.0/2145.1.176.1 to 45.1.183.25445.1.183.2552,046
5645.1.184.0/2145.1.184.1 to 45.1.191.25445.1.191.2552,046
5745.1.192.0/2145.1.192.1 to 45.1.199.25445.1.199.2552,046
5845.1.200.0/2145.1.200.1 to 45.1.207.25445.1.207.2552,046
5945.1.208.0/2145.1.208.1 to 45.1.215.25445.1.215.2552,046
6045.1.216.0/2145.1.216.1 to 45.1.223.25445.1.223.2552,046
6145.1.224.0/2145.1.224.1 to 45.1.231.25445.1.231.2552,046
6245.1.232.0/2145.1.232.1 to 45.1.239.25445.1.239.2552,046
6345.1.240.0/2145.1.240.1 to 45.1.247.25445.1.247.2552,046
6445.1.248.0/2145.1.248.1 to 45.1.255.25445.1.255.2552,046
6545.2.0.0/2145.2.0.1 to 45.2.7.25445.2.7.2552,046
6645.2.8.0/2145.2.8.1 to 45.2.15.25445.2.15.2552,046
6745.2.16.0/2145.2.16.1 to 45.2.23.25445.2.23.2552,046
6845.2.24.0/2145.2.24.1 to 45.2.31.25445.2.31.2552,046
6945.2.32.0/2145.2.32.1 to 45.2.39.25445.2.39.2552,046
7045.2.40.0/2145.2.40.1 to 45.2.47.25445.2.47.2552,046
7145.2.48.0/2145.2.48.1 to 45.2.55.25445.2.55.2552,046
7245.2.56.0/2145.2.56.1 to 45.2.63.25445.2.63.2552,046
7345.2.64.0/2145.2.64.1 to 45.2.71.25445.2.71.2552,046
7445.2.72.0/2145.2.72.1 to 45.2.79.25445.2.79.2552,046
7545.2.80.0/2145.2.80.1 to 45.2.87.25445.2.87.2552,046
7645.2.88.0/2145.2.88.1 to 45.2.95.25445.2.95.2552,046
7745.2.96.0/2145.2.96.1 to 45.2.103.25445.2.103.2552,046
7845.2.104.0/2145.2.104.1 to 45.2.111.25445.2.111.2552,046
7945.2.112.0/2145.2.112.1 to 45.2.119.25445.2.119.2552,046
8045.2.120.0/2145.2.120.1 to 45.2.127.25445.2.127.2552,046
8145.2.128.0/2145.2.128.1 to 45.2.135.25445.2.135.2552,046
8245.2.136.0/2145.2.136.1 to 45.2.143.25445.2.143.2552,046
8345.2.144.0/2145.2.144.1 to 45.2.151.25445.2.151.2552,046
8445.2.152.0/2145.2.152.1 to 45.2.159.25445.2.159.2552,046
8545.2.160.0/2145.2.160.1 to 45.2.167.25445.2.167.2552,046
8645.2.168.0/2145.2.168.1 to 45.2.175.25445.2.175.2552,046
8745.2.176.0/2145.2.176.1 to 45.2.183.25445.2.183.2552,046
8845.2.184.0/2145.2.184.1 to 45.2.191.25445.2.191.2552,046
8945.2.192.0/2145.2.192.1 to 45.2.199.25445.2.199.2552,046
9045.2.200.0/2145.2.200.1 to 45.2.207.25445.2.207.2552,046
9145.2.208.0/2145.2.208.1 to 45.2.215.25445.2.215.2552,046
9245.2.216.0/2145.2.216.1 to 45.2.223.25445.2.223.2552,046
9345.2.224.0/2145.2.224.1 to 45.2.231.25445.2.231.2552,046
9445.2.232.0/2145.2.232.1 to 45.2.239.25445.2.239.2552,046
9545.2.240.0/2145.2.240.1 to 45.2.247.25445.2.247.2552,046
9645.2.248.0/2145.2.248.1 to 45.2.255.25445.2.255.2552,046
9745.3.0.0/2145.3.0.1 to 45.3.7.25445.3.7.2552,046
9845.3.8.0/2145.3.8.1 to 45.3.15.25445.3.15.2552,046
9945.3.16.0/2145.3.16.1 to 45.3.23.25445.3.23.2552,046
10045.3.24.0/2145.3.24.1 to 45.3.31.25445.3.31.2552,046
10145.3.32.0/2145.3.32.1 to 45.3.39.25445.3.39.2552,046
10245.3.40.0/2145.3.40.1 to 45.3.47.25445.3.47.2552,046
10345.3.48.0/2145.3.48.1 to 45.3.55.25445.3.55.2552,046
10445.3.56.0/2145.3.56.1 to 45.3.63.25445.3.63.2552,046
10545.3.64.0/2145.3.64.1 to 45.3.71.25445.3.71.2552,046
10645.3.72.0/2145.3.72.1 to 45.3.79.25445.3.79.2552,046
10745.3.80.0/2145.3.80.1 to 45.3.87.25445.3.87.2552,046
10845.3.88.0/2145.3.88.1 to 45.3.95.25445.3.95.2552,046
10945.3.96.0/2145.3.96.1 to 45.3.103.25445.3.103.2552,046
11045.3.104.0/2145.3.104.1 to 45.3.111.25445.3.111.2552,046
11145.3.112.0/2145.3.112.1 to 45.3.119.25445.3.119.2552,046
11245.3.120.0/2145.3.120.1 to 45.3.127.25445.3.127.2552,046
11345.3.128.0/2145.3.128.1 to 45.3.135.25445.3.135.2552,046
11445.3.136.0/2145.3.136.1 to 45.3.143.25445.3.143.2552,046
11545.3.144.0/2145.3.144.1 to 45.3.151.25445.3.151.2552,046
11645.3.152.0/2145.3.152.1 to 45.3.159.25445.3.159.2552,046
11745.3.160.0/2145.3.160.1 to 45.3.167.25445.3.167.2552,046
11845.3.168.0/2145.3.168.1 to 45.3.175.25445.3.175.2552,046
11945.3.176.0/2145.3.176.1 to 45.3.183.25445.3.183.2552,046
12045.3.184.0/2145.3.184.1 to 45.3.191.25445.3.191.2552,046
12145.3.192.0/2145.3.192.1 to 45.3.199.25445.3.199.2552,046
12245.3.200.0/2145.3.200.1 to 45.3.207.25445.3.207.2552,046
12345.3.208.0/2145.3.208.1 to 45.3.215.25445.3.215.2552,046
12445.3.216.0/2145.3.216.1 to 45.3.223.25445.3.223.2552,046
12545.3.224.0/2145.3.224.1 to 45.3.231.25445.3.231.2552,046
12645.3.232.0/2145.3.232.1 to 45.3.239.25445.3.239.2552,046
12745.3.240.0/2145.3.240.1 to 45.3.247.25445.3.247.2552,046
12845.3.248.0/2145.3.248.1 to 45.3.255.25445.3.255.2552,046
12945.4.0.0/2145.4.0.1 to 45.4.7.25445.4.7.2552,046
13045.4.8.0/2145.4.8.1 to 45.4.15.25445.4.15.2552,046
13145.4.16.0/2145.4.16.1 to 45.4.23.25445.4.23.2552,046
13245.4.24.0/2145.4.24.1 to 45.4.31.25445.4.31.2552,046
13345.4.32.0/2145.4.32.1 to 45.4.39.25445.4.39.2552,046
13445.4.40.0/2145.4.40.1 to 45.4.47.25445.4.47.2552,046
13545.4.48.0/2145.4.48.1 to 45.4.55.25445.4.55.2552,046
13645.4.56.0/2145.4.56.1 to 45.4.63.25445.4.63.2552,046
13745.4.64.0/2145.4.64.1 to 45.4.71.25445.4.71.2552,046
13845.4.72.0/2145.4.72.1 to 45.4.79.25445.4.79.2552,046
13945.4.80.0/2145.4.80.1 to 45.4.87.25445.4.87.2552,046
14045.4.88.0/2145.4.88.1 to 45.4.95.25445.4.95.2552,046
14145.4.96.0/2145.4.96.1 to 45.4.103.25445.4.103.2552,046
14245.4.104.0/2145.4.104.1 to 45.4.111.25445.4.111.2552,046
14345.4.112.0/2145.4.112.1 to 45.4.119.25445.4.119.2552,046
14445.4.120.0/2145.4.120.1 to 45.4.127.25445.4.127.2552,046
14545.4.128.0/2145.4.128.1 to 45.4.135.25445.4.135.2552,046
14645.4.136.0/2145.4.136.1 to 45.4.143.25445.4.143.2552,046
14745.4.144.0/2145.4.144.1 to 45.4.151.25445.4.151.2552,046
14845.4.152.0/2145.4.152.1 to 45.4.159.25445.4.159.2552,046
14945.4.160.0/2145.4.160.1 to 45.4.167.25445.4.167.2552,046
15045.4.168.0/2145.4.168.1 to 45.4.175.25445.4.175.2552,046
15145.4.176.0/2145.4.176.1 to 45.4.183.25445.4.183.2552,046
15245.4.184.0/2145.4.184.1 to 45.4.191.25445.4.191.2552,046
15345.4.192.0/2145.4.192.1 to 45.4.199.25445.4.199.2552,046
15445.4.200.0/2145.4.200.1 to 45.4.207.25445.4.207.2552,046
15545.4.208.0/2145.4.208.1 to 45.4.215.25445.4.215.2552,046
15645.4.216.0/2145.4.216.1 to 45.4.223.25445.4.223.2552,046
15745.4.224.0/2145.4.224.1 to 45.4.231.25445.4.231.2552,046
15845.4.232.0/2145.4.232.1 to 45.4.239.25445.4.239.2552,046
15945.4.240.0/2145.4.240.1 to 45.4.247.25445.4.247.2552,046
16045.4.248.0/2145.4.248.1 to 45.4.255.25445.4.255.2552,046
16145.5.0.0/2145.5.0.1 to 45.5.7.25445.5.7.2552,046
16245.5.8.0/2145.5.8.1 to 45.5.15.25445.5.15.2552,046
16345.5.16.0/2145.5.16.1 to 45.5.23.25445.5.23.2552,046
16445.5.24.0/2145.5.24.1 to 45.5.31.25445.5.31.2552,046
16545.5.32.0/2145.5.32.1 to 45.5.39.25445.5.39.2552,046
16645.5.40.0/2145.5.40.1 to 45.5.47.25445.5.47.2552,046
16745.5.48.0/2145.5.48.1 to 45.5.55.25445.5.55.2552,046
16845.5.56.0/2145.5.56.1 to 45.5.63.25445.5.63.2552,046
16945.5.64.0/2145.5.64.1 to 45.5.71.25445.5.71.2552,046
17045.5.72.0/2145.5.72.1 to 45.5.79.25445.5.79.2552,046
17145.5.80.0/2145.5.80.1 to 45.5.87.25445.5.87.2552,046
17245.5.88.0/2145.5.88.1 to 45.5.95.25445.5.95.2552,046
17345.5.96.0/2145.5.96.1 to 45.5.103.25445.5.103.2552,046
17445.5.104.0/2145.5.104.1 to 45.5.111.25445.5.111.2552,046
17545.5.112.0/2145.5.112.1 to 45.5.119.25445.5.119.2552,046
17645.5.120.0/2145.5.120.1 to 45.5.127.25445.5.127.2552,046
17745.5.128.0/2145.5.128.1 to 45.5.135.25445.5.135.2552,046
17845.5.136.0/2145.5.136.1 to 45.5.143.25445.5.143.2552,046
17945.5.144.0/2145.5.144.1 to 45.5.151.25445.5.151.2552,046
18045.5.152.0/2145.5.152.1 to 45.5.159.25445.5.159.2552,046
18145.5.160.0/2145.5.160.1 to 45.5.167.25445.5.167.2552,046
18245.5.168.0/2145.5.168.1 to 45.5.175.25445.5.175.2552,046
18345.5.176.0/2145.5.176.1 to 45.5.183.25445.5.183.2552,046
18445.5.184.0/2145.5.184.1 to 45.5.191.25445.5.191.2552,046
18545.5.192.0/2145.5.192.1 to 45.5.199.25445.5.199.2552,046
18645.5.200.0/2145.5.200.1 to 45.5.207.25445.5.207.2552,046
18745.5.208.0/2145.5.208.1 to 45.5.215.25445.5.215.2552,046
18845.5.216.0/2145.5.216.1 to 45.5.223.25445.5.223.2552,046
18945.5.224.0/2145.5.224.1 to 45.5.231.25445.5.231.2552,046
19045.5.232.0/2145.5.232.1 to 45.5.239.25445.5.239.2552,046
19145.5.240.0/2145.5.240.1 to 45.5.247.25445.5.247.2552,046
19245.5.248.0/2145.5.248.1 to 45.5.255.25445.5.255.2552,046
19345.6.0.0/2145.6.0.1 to 45.6.7.25445.6.7.2552,046
19445.6.8.0/2145.6.8.1 to 45.6.15.25445.6.15.2552,046
19545.6.16.0/2145.6.16.1 to 45.6.23.25445.6.23.2552,046
19645.6.24.0/2145.6.24.1 to 45.6.31.25445.6.31.2552,046
19745.6.32.0/2145.6.32.1 to 45.6.39.25445.6.39.2552,046
19845.6.40.0/2145.6.40.1 to 45.6.47.25445.6.47.2552,046
19945.6.48.0/2145.6.48.1 to 45.6.55.25445.6.55.2552,046
20045.6.56.0/2145.6.56.1 to 45.6.63.25445.6.63.2552,046
20145.6.64.0/2145.6.64.1 to 45.6.71.25445.6.71.2552,046
20245.6.72.0/2145.6.72.1 to 45.6.79.25445.6.79.2552,046
20345.6.80.0/2145.6.80.1 to 45.6.87.25445.6.87.2552,046
20445.6.88.0/2145.6.88.1 to 45.6.95.25445.6.95.2552,046
20545.6.96.0/2145.6.96.1 to 45.6.103.25445.6.103.2552,046
20645.6.104.0/2145.6.104.1 to 45.6.111.25445.6.111.2552,046
20745.6.112.0/2145.6.112.1 to 45.6.119.25445.6.119.2552,046
20845.6.120.0/2145.6.120.1 to 45.6.127.25445.6.127.2552,046
20945.6.128.0/2145.6.128.1 to 45.6.135.25445.6.135.2552,046
21045.6.136.0/2145.6.136.1 to 45.6.143.25445.6.143.2552,046
21145.6.144.0/2145.6.144.1 to 45.6.151.25445.6.151.2552,046
21245.6.152.0/2145.6.152.1 to 45.6.159.25445.6.159.2552,046
21345.6.160.0/2145.6.160.1 to 45.6.167.25445.6.167.2552,046
21445.6.168.0/2145.6.168.1 to 45.6.175.25445.6.175.2552,046
21545.6.176.0/2145.6.176.1 to 45.6.183.25445.6.183.2552,046
21645.6.184.0/2145.6.184.1 to 45.6.191.25445.6.191.2552,046
21745.6.192.0/2145.6.192.1 to 45.6.199.25445.6.199.2552,046
21845.6.200.0/2145.6.200.1 to 45.6.207.25445.6.207.2552,046
21945.6.208.0/2145.6.208.1 to 45.6.215.25445.6.215.2552,046
22045.6.216.0/2145.6.216.1 to 45.6.223.25445.6.223.2552,046
22145.6.224.0/2145.6.224.1 to 45.6.231.25445.6.231.2552,046
22245.6.232.0/2145.6.232.1 to 45.6.239.25445.6.239.2552,046
22345.6.240.0/2145.6.240.1 to 45.6.247.25445.6.247.2552,046
22445.6.248.0/2145.6.248.1 to 45.6.255.25445.6.255.2552,046
22545.7.0.0/2145.7.0.1 to 45.7.7.25445.7.7.2552,046
22645.7.8.0/2145.7.8.1 to 45.7.15.25445.7.15.2552,046
22745.7.16.0/2145.7.16.1 to 45.7.23.25445.7.23.2552,046
22845.7.24.0/2145.7.24.1 to 45.7.31.25445.7.31.2552,046
22945.7.32.0/2145.7.32.1 to 45.7.39.25445.7.39.2552,046
23045.7.40.0/2145.7.40.1 to 45.7.47.25445.7.47.2552,046
23145.7.48.0/2145.7.48.1 to 45.7.55.25445.7.55.2552,046
23245.7.56.0/2145.7.56.1 to 45.7.63.25445.7.63.2552,046
23345.7.64.0/2145.7.64.1 to 45.7.71.25445.7.71.2552,046
23445.7.72.0/2145.7.72.1 to 45.7.79.25445.7.79.2552,046
23545.7.80.0/2145.7.80.1 to 45.7.87.25445.7.87.2552,046
23645.7.88.0/2145.7.88.1 to 45.7.95.25445.7.95.2552,046
23745.7.96.0/2145.7.96.1 to 45.7.103.25445.7.103.2552,046
23845.7.104.0/2145.7.104.1 to 45.7.111.25445.7.111.2552,046
23945.7.112.0/2145.7.112.1 to 45.7.119.25445.7.119.2552,046
24045.7.120.0/2145.7.120.1 to 45.7.127.25445.7.127.2552,046
24145.7.128.0/2145.7.128.1 to 45.7.135.25445.7.135.2552,046
24245.7.136.0/2145.7.136.1 to 45.7.143.25445.7.143.2552,046
24345.7.144.0/2145.7.144.1 to 45.7.151.25445.7.151.2552,046
24445.7.152.0/2145.7.152.1 to 45.7.159.25445.7.159.2552,046
24545.7.160.0/2145.7.160.1 to 45.7.167.25445.7.167.2552,046
24645.7.168.0/2145.7.168.1 to 45.7.175.25445.7.175.2552,046
24745.7.176.0/2145.7.176.1 to 45.7.183.25445.7.183.2552,046
24845.7.184.0/2145.7.184.1 to 45.7.191.25445.7.191.2552,046
24945.7.192.0/2145.7.192.1 to 45.7.199.25445.7.199.2552,046
25045.7.200.0/2145.7.200.1 to 45.7.207.25445.7.207.2552,046
25145.7.208.0/2145.7.208.1 to 45.7.215.25445.7.215.2552,046
25245.7.216.0/2145.7.216.1 to 45.7.223.25445.7.223.2552,046
25345.7.224.0/2145.7.224.1 to 45.7.231.25445.7.231.2552,046
25445.7.232.0/2145.7.232.1 to 45.7.239.25445.7.239.2552,046
25545.7.240.0/2145.7.240.1 to 45.7.247.25445.7.247.2552,046
25645.7.248.0/2145.7.248.1 to 45.7.255.25445.7.255.2552,046

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.