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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.

Network20.0.0.0/9
Usable hosts8,388,606
Subnet mask255.128.0.0
Addresses8,388,608
Network address
20.0.0.0
Broadcast address
20.127.255.255
First usable
20.0.0.1
Last usable
20.127.255.254
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 14000000 · Integer 335544320 to 343932927
Reverse DNS zones
0.20.in-addr.arpa
1.20.in-addr.arpa
2.20.in-addr.arpa
3.20.in-addr.arpa
4.20.in-addr.arpa
5.20.in-addr.arpa
6.20.in-addr.arpa
7.20.in-addr.arpa
8.20.in-addr.arpa
9.20.in-addr.arpa
10.20.in-addr.arpa
11.20.in-addr.arpa
12.20.in-addr.arpa
13.20.in-addr.arpa
14.20.in-addr.arpa
15.20.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
Address00010100.00000000.00000000.0000000020.0.0.0
Subnet mask11111111.10000000.00000000.00000000255.128.0.0
Network00010100.00000000.00000000.0000000020.0.0.0
Broadcast00010100.01111111.11111111.1111111120.127.255.255
Split into smaller subnets/20
/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)

20.0.0.0/9 makes 2,048 subnets of /20; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
120.0.0.0/2020.0.0.1 to 20.0.15.25420.0.15.2554,094
220.0.16.0/2020.0.16.1 to 20.0.31.25420.0.31.2554,094
320.0.32.0/2020.0.32.1 to 20.0.47.25420.0.47.2554,094
420.0.48.0/2020.0.48.1 to 20.0.63.25420.0.63.2554,094
520.0.64.0/2020.0.64.1 to 20.0.79.25420.0.79.2554,094
620.0.80.0/2020.0.80.1 to 20.0.95.25420.0.95.2554,094
720.0.96.0/2020.0.96.1 to 20.0.111.25420.0.111.2554,094
820.0.112.0/2020.0.112.1 to 20.0.127.25420.0.127.2554,094
920.0.128.0/2020.0.128.1 to 20.0.143.25420.0.143.2554,094
1020.0.144.0/2020.0.144.1 to 20.0.159.25420.0.159.2554,094
1120.0.160.0/2020.0.160.1 to 20.0.175.25420.0.175.2554,094
1220.0.176.0/2020.0.176.1 to 20.0.191.25420.0.191.2554,094
1320.0.192.0/2020.0.192.1 to 20.0.207.25420.0.207.2554,094
1420.0.208.0/2020.0.208.1 to 20.0.223.25420.0.223.2554,094
1520.0.224.0/2020.0.224.1 to 20.0.239.25420.0.239.2554,094
1620.0.240.0/2020.0.240.1 to 20.0.255.25420.0.255.2554,094
1720.1.0.0/2020.1.0.1 to 20.1.15.25420.1.15.2554,094
1820.1.16.0/2020.1.16.1 to 20.1.31.25420.1.31.2554,094
1920.1.32.0/2020.1.32.1 to 20.1.47.25420.1.47.2554,094
2020.1.48.0/2020.1.48.1 to 20.1.63.25420.1.63.2554,094
2120.1.64.0/2020.1.64.1 to 20.1.79.25420.1.79.2554,094
2220.1.80.0/2020.1.80.1 to 20.1.95.25420.1.95.2554,094
2320.1.96.0/2020.1.96.1 to 20.1.111.25420.1.111.2554,094
2420.1.112.0/2020.1.112.1 to 20.1.127.25420.1.127.2554,094
2520.1.128.0/2020.1.128.1 to 20.1.143.25420.1.143.2554,094
2620.1.144.0/2020.1.144.1 to 20.1.159.25420.1.159.2554,094
2720.1.160.0/2020.1.160.1 to 20.1.175.25420.1.175.2554,094
2820.1.176.0/2020.1.176.1 to 20.1.191.25420.1.191.2554,094
2920.1.192.0/2020.1.192.1 to 20.1.207.25420.1.207.2554,094
3020.1.208.0/2020.1.208.1 to 20.1.223.25420.1.223.2554,094
3120.1.224.0/2020.1.224.1 to 20.1.239.25420.1.239.2554,094
3220.1.240.0/2020.1.240.1 to 20.1.255.25420.1.255.2554,094
3320.2.0.0/2020.2.0.1 to 20.2.15.25420.2.15.2554,094
3420.2.16.0/2020.2.16.1 to 20.2.31.25420.2.31.2554,094
3520.2.32.0/2020.2.32.1 to 20.2.47.25420.2.47.2554,094
3620.2.48.0/2020.2.48.1 to 20.2.63.25420.2.63.2554,094
3720.2.64.0/2020.2.64.1 to 20.2.79.25420.2.79.2554,094
3820.2.80.0/2020.2.80.1 to 20.2.95.25420.2.95.2554,094
3920.2.96.0/2020.2.96.1 to 20.2.111.25420.2.111.2554,094
4020.2.112.0/2020.2.112.1 to 20.2.127.25420.2.127.2554,094
4120.2.128.0/2020.2.128.1 to 20.2.143.25420.2.143.2554,094
4220.2.144.0/2020.2.144.1 to 20.2.159.25420.2.159.2554,094
4320.2.160.0/2020.2.160.1 to 20.2.175.25420.2.175.2554,094
4420.2.176.0/2020.2.176.1 to 20.2.191.25420.2.191.2554,094
4520.2.192.0/2020.2.192.1 to 20.2.207.25420.2.207.2554,094
4620.2.208.0/2020.2.208.1 to 20.2.223.25420.2.223.2554,094
4720.2.224.0/2020.2.224.1 to 20.2.239.25420.2.239.2554,094
4820.2.240.0/2020.2.240.1 to 20.2.255.25420.2.255.2554,094
4920.3.0.0/2020.3.0.1 to 20.3.15.25420.3.15.2554,094
5020.3.16.0/2020.3.16.1 to 20.3.31.25420.3.31.2554,094
5120.3.32.0/2020.3.32.1 to 20.3.47.25420.3.47.2554,094
5220.3.48.0/2020.3.48.1 to 20.3.63.25420.3.63.2554,094
5320.3.64.0/2020.3.64.1 to 20.3.79.25420.3.79.2554,094
5420.3.80.0/2020.3.80.1 to 20.3.95.25420.3.95.2554,094
5520.3.96.0/2020.3.96.1 to 20.3.111.25420.3.111.2554,094
5620.3.112.0/2020.3.112.1 to 20.3.127.25420.3.127.2554,094
5720.3.128.0/2020.3.128.1 to 20.3.143.25420.3.143.2554,094
5820.3.144.0/2020.3.144.1 to 20.3.159.25420.3.159.2554,094
5920.3.160.0/2020.3.160.1 to 20.3.175.25420.3.175.2554,094
6020.3.176.0/2020.3.176.1 to 20.3.191.25420.3.191.2554,094
6120.3.192.0/2020.3.192.1 to 20.3.207.25420.3.207.2554,094
6220.3.208.0/2020.3.208.1 to 20.3.223.25420.3.223.2554,094
6320.3.224.0/2020.3.224.1 to 20.3.239.25420.3.239.2554,094
6420.3.240.0/2020.3.240.1 to 20.3.255.25420.3.255.2554,094
6520.4.0.0/2020.4.0.1 to 20.4.15.25420.4.15.2554,094
6620.4.16.0/2020.4.16.1 to 20.4.31.25420.4.31.2554,094
6720.4.32.0/2020.4.32.1 to 20.4.47.25420.4.47.2554,094
6820.4.48.0/2020.4.48.1 to 20.4.63.25420.4.63.2554,094
6920.4.64.0/2020.4.64.1 to 20.4.79.25420.4.79.2554,094
7020.4.80.0/2020.4.80.1 to 20.4.95.25420.4.95.2554,094
7120.4.96.0/2020.4.96.1 to 20.4.111.25420.4.111.2554,094
7220.4.112.0/2020.4.112.1 to 20.4.127.25420.4.127.2554,094
7320.4.128.0/2020.4.128.1 to 20.4.143.25420.4.143.2554,094
7420.4.144.0/2020.4.144.1 to 20.4.159.25420.4.159.2554,094
7520.4.160.0/2020.4.160.1 to 20.4.175.25420.4.175.2554,094
7620.4.176.0/2020.4.176.1 to 20.4.191.25420.4.191.2554,094
7720.4.192.0/2020.4.192.1 to 20.4.207.25420.4.207.2554,094
7820.4.208.0/2020.4.208.1 to 20.4.223.25420.4.223.2554,094
7920.4.224.0/2020.4.224.1 to 20.4.239.25420.4.239.2554,094
8020.4.240.0/2020.4.240.1 to 20.4.255.25420.4.255.2554,094
8120.5.0.0/2020.5.0.1 to 20.5.15.25420.5.15.2554,094
8220.5.16.0/2020.5.16.1 to 20.5.31.25420.5.31.2554,094
8320.5.32.0/2020.5.32.1 to 20.5.47.25420.5.47.2554,094
8420.5.48.0/2020.5.48.1 to 20.5.63.25420.5.63.2554,094
8520.5.64.0/2020.5.64.1 to 20.5.79.25420.5.79.2554,094
8620.5.80.0/2020.5.80.1 to 20.5.95.25420.5.95.2554,094
8720.5.96.0/2020.5.96.1 to 20.5.111.25420.5.111.2554,094
8820.5.112.0/2020.5.112.1 to 20.5.127.25420.5.127.2554,094
8920.5.128.0/2020.5.128.1 to 20.5.143.25420.5.143.2554,094
9020.5.144.0/2020.5.144.1 to 20.5.159.25420.5.159.2554,094
9120.5.160.0/2020.5.160.1 to 20.5.175.25420.5.175.2554,094
9220.5.176.0/2020.5.176.1 to 20.5.191.25420.5.191.2554,094
9320.5.192.0/2020.5.192.1 to 20.5.207.25420.5.207.2554,094
9420.5.208.0/2020.5.208.1 to 20.5.223.25420.5.223.2554,094
9520.5.224.0/2020.5.224.1 to 20.5.239.25420.5.239.2554,094
9620.5.240.0/2020.5.240.1 to 20.5.255.25420.5.255.2554,094
9720.6.0.0/2020.6.0.1 to 20.6.15.25420.6.15.2554,094
9820.6.16.0/2020.6.16.1 to 20.6.31.25420.6.31.2554,094
9920.6.32.0/2020.6.32.1 to 20.6.47.25420.6.47.2554,094
10020.6.48.0/2020.6.48.1 to 20.6.63.25420.6.63.2554,094
10120.6.64.0/2020.6.64.1 to 20.6.79.25420.6.79.2554,094
10220.6.80.0/2020.6.80.1 to 20.6.95.25420.6.95.2554,094
10320.6.96.0/2020.6.96.1 to 20.6.111.25420.6.111.2554,094
10420.6.112.0/2020.6.112.1 to 20.6.127.25420.6.127.2554,094
10520.6.128.0/2020.6.128.1 to 20.6.143.25420.6.143.2554,094
10620.6.144.0/2020.6.144.1 to 20.6.159.25420.6.159.2554,094
10720.6.160.0/2020.6.160.1 to 20.6.175.25420.6.175.2554,094
10820.6.176.0/2020.6.176.1 to 20.6.191.25420.6.191.2554,094
10920.6.192.0/2020.6.192.1 to 20.6.207.25420.6.207.2554,094
11020.6.208.0/2020.6.208.1 to 20.6.223.25420.6.223.2554,094
11120.6.224.0/2020.6.224.1 to 20.6.239.25420.6.239.2554,094
11220.6.240.0/2020.6.240.1 to 20.6.255.25420.6.255.2554,094
11320.7.0.0/2020.7.0.1 to 20.7.15.25420.7.15.2554,094
11420.7.16.0/2020.7.16.1 to 20.7.31.25420.7.31.2554,094
11520.7.32.0/2020.7.32.1 to 20.7.47.25420.7.47.2554,094
11620.7.48.0/2020.7.48.1 to 20.7.63.25420.7.63.2554,094
11720.7.64.0/2020.7.64.1 to 20.7.79.25420.7.79.2554,094
11820.7.80.0/2020.7.80.1 to 20.7.95.25420.7.95.2554,094
11920.7.96.0/2020.7.96.1 to 20.7.111.25420.7.111.2554,094
12020.7.112.0/2020.7.112.1 to 20.7.127.25420.7.127.2554,094
12120.7.128.0/2020.7.128.1 to 20.7.143.25420.7.143.2554,094
12220.7.144.0/2020.7.144.1 to 20.7.159.25420.7.159.2554,094
12320.7.160.0/2020.7.160.1 to 20.7.175.25420.7.175.2554,094
12420.7.176.0/2020.7.176.1 to 20.7.191.25420.7.191.2554,094
12520.7.192.0/2020.7.192.1 to 20.7.207.25420.7.207.2554,094
12620.7.208.0/2020.7.208.1 to 20.7.223.25420.7.223.2554,094
12720.7.224.0/2020.7.224.1 to 20.7.239.25420.7.239.2554,094
12820.7.240.0/2020.7.240.1 to 20.7.255.25420.7.255.2554,094
12920.8.0.0/2020.8.0.1 to 20.8.15.25420.8.15.2554,094
13020.8.16.0/2020.8.16.1 to 20.8.31.25420.8.31.2554,094
13120.8.32.0/2020.8.32.1 to 20.8.47.25420.8.47.2554,094
13220.8.48.0/2020.8.48.1 to 20.8.63.25420.8.63.2554,094
13320.8.64.0/2020.8.64.1 to 20.8.79.25420.8.79.2554,094
13420.8.80.0/2020.8.80.1 to 20.8.95.25420.8.95.2554,094
13520.8.96.0/2020.8.96.1 to 20.8.111.25420.8.111.2554,094
13620.8.112.0/2020.8.112.1 to 20.8.127.25420.8.127.2554,094
13720.8.128.0/2020.8.128.1 to 20.8.143.25420.8.143.2554,094
13820.8.144.0/2020.8.144.1 to 20.8.159.25420.8.159.2554,094
13920.8.160.0/2020.8.160.1 to 20.8.175.25420.8.175.2554,094
14020.8.176.0/2020.8.176.1 to 20.8.191.25420.8.191.2554,094
14120.8.192.0/2020.8.192.1 to 20.8.207.25420.8.207.2554,094
14220.8.208.0/2020.8.208.1 to 20.8.223.25420.8.223.2554,094
14320.8.224.0/2020.8.224.1 to 20.8.239.25420.8.239.2554,094
14420.8.240.0/2020.8.240.1 to 20.8.255.25420.8.255.2554,094
14520.9.0.0/2020.9.0.1 to 20.9.15.25420.9.15.2554,094
14620.9.16.0/2020.9.16.1 to 20.9.31.25420.9.31.2554,094
14720.9.32.0/2020.9.32.1 to 20.9.47.25420.9.47.2554,094
14820.9.48.0/2020.9.48.1 to 20.9.63.25420.9.63.2554,094
14920.9.64.0/2020.9.64.1 to 20.9.79.25420.9.79.2554,094
15020.9.80.0/2020.9.80.1 to 20.9.95.25420.9.95.2554,094
15120.9.96.0/2020.9.96.1 to 20.9.111.25420.9.111.2554,094
15220.9.112.0/2020.9.112.1 to 20.9.127.25420.9.127.2554,094
15320.9.128.0/2020.9.128.1 to 20.9.143.25420.9.143.2554,094
15420.9.144.0/2020.9.144.1 to 20.9.159.25420.9.159.2554,094
15520.9.160.0/2020.9.160.1 to 20.9.175.25420.9.175.2554,094
15620.9.176.0/2020.9.176.1 to 20.9.191.25420.9.191.2554,094
15720.9.192.0/2020.9.192.1 to 20.9.207.25420.9.207.2554,094
15820.9.208.0/2020.9.208.1 to 20.9.223.25420.9.223.2554,094
15920.9.224.0/2020.9.224.1 to 20.9.239.25420.9.239.2554,094
16020.9.240.0/2020.9.240.1 to 20.9.255.25420.9.255.2554,094
16120.10.0.0/2020.10.0.1 to 20.10.15.25420.10.15.2554,094
16220.10.16.0/2020.10.16.1 to 20.10.31.25420.10.31.2554,094
16320.10.32.0/2020.10.32.1 to 20.10.47.25420.10.47.2554,094
16420.10.48.0/2020.10.48.1 to 20.10.63.25420.10.63.2554,094
16520.10.64.0/2020.10.64.1 to 20.10.79.25420.10.79.2554,094
16620.10.80.0/2020.10.80.1 to 20.10.95.25420.10.95.2554,094
16720.10.96.0/2020.10.96.1 to 20.10.111.25420.10.111.2554,094
16820.10.112.0/2020.10.112.1 to 20.10.127.25420.10.127.2554,094
16920.10.128.0/2020.10.128.1 to 20.10.143.25420.10.143.2554,094
17020.10.144.0/2020.10.144.1 to 20.10.159.25420.10.159.2554,094
17120.10.160.0/2020.10.160.1 to 20.10.175.25420.10.175.2554,094
17220.10.176.0/2020.10.176.1 to 20.10.191.25420.10.191.2554,094
17320.10.192.0/2020.10.192.1 to 20.10.207.25420.10.207.2554,094
17420.10.208.0/2020.10.208.1 to 20.10.223.25420.10.223.2554,094
17520.10.224.0/2020.10.224.1 to 20.10.239.25420.10.239.2554,094
17620.10.240.0/2020.10.240.1 to 20.10.255.25420.10.255.2554,094
17720.11.0.0/2020.11.0.1 to 20.11.15.25420.11.15.2554,094
17820.11.16.0/2020.11.16.1 to 20.11.31.25420.11.31.2554,094
17920.11.32.0/2020.11.32.1 to 20.11.47.25420.11.47.2554,094
18020.11.48.0/2020.11.48.1 to 20.11.63.25420.11.63.2554,094
18120.11.64.0/2020.11.64.1 to 20.11.79.25420.11.79.2554,094
18220.11.80.0/2020.11.80.1 to 20.11.95.25420.11.95.2554,094
18320.11.96.0/2020.11.96.1 to 20.11.111.25420.11.111.2554,094
18420.11.112.0/2020.11.112.1 to 20.11.127.25420.11.127.2554,094
18520.11.128.0/2020.11.128.1 to 20.11.143.25420.11.143.2554,094
18620.11.144.0/2020.11.144.1 to 20.11.159.25420.11.159.2554,094
18720.11.160.0/2020.11.160.1 to 20.11.175.25420.11.175.2554,094
18820.11.176.0/2020.11.176.1 to 20.11.191.25420.11.191.2554,094
18920.11.192.0/2020.11.192.1 to 20.11.207.25420.11.207.2554,094
19020.11.208.0/2020.11.208.1 to 20.11.223.25420.11.223.2554,094
19120.11.224.0/2020.11.224.1 to 20.11.239.25420.11.239.2554,094
19220.11.240.0/2020.11.240.1 to 20.11.255.25420.11.255.2554,094
19320.12.0.0/2020.12.0.1 to 20.12.15.25420.12.15.2554,094
19420.12.16.0/2020.12.16.1 to 20.12.31.25420.12.31.2554,094
19520.12.32.0/2020.12.32.1 to 20.12.47.25420.12.47.2554,094
19620.12.48.0/2020.12.48.1 to 20.12.63.25420.12.63.2554,094
19720.12.64.0/2020.12.64.1 to 20.12.79.25420.12.79.2554,094
19820.12.80.0/2020.12.80.1 to 20.12.95.25420.12.95.2554,094
19920.12.96.0/2020.12.96.1 to 20.12.111.25420.12.111.2554,094
20020.12.112.0/2020.12.112.1 to 20.12.127.25420.12.127.2554,094
20120.12.128.0/2020.12.128.1 to 20.12.143.25420.12.143.2554,094
20220.12.144.0/2020.12.144.1 to 20.12.159.25420.12.159.2554,094
20320.12.160.0/2020.12.160.1 to 20.12.175.25420.12.175.2554,094
20420.12.176.0/2020.12.176.1 to 20.12.191.25420.12.191.2554,094
20520.12.192.0/2020.12.192.1 to 20.12.207.25420.12.207.2554,094
20620.12.208.0/2020.12.208.1 to 20.12.223.25420.12.223.2554,094
20720.12.224.0/2020.12.224.1 to 20.12.239.25420.12.239.2554,094
20820.12.240.0/2020.12.240.1 to 20.12.255.25420.12.255.2554,094
20920.13.0.0/2020.13.0.1 to 20.13.15.25420.13.15.2554,094
21020.13.16.0/2020.13.16.1 to 20.13.31.25420.13.31.2554,094
21120.13.32.0/2020.13.32.1 to 20.13.47.25420.13.47.2554,094
21220.13.48.0/2020.13.48.1 to 20.13.63.25420.13.63.2554,094
21320.13.64.0/2020.13.64.1 to 20.13.79.25420.13.79.2554,094
21420.13.80.0/2020.13.80.1 to 20.13.95.25420.13.95.2554,094
21520.13.96.0/2020.13.96.1 to 20.13.111.25420.13.111.2554,094
21620.13.112.0/2020.13.112.1 to 20.13.127.25420.13.127.2554,094
21720.13.128.0/2020.13.128.1 to 20.13.143.25420.13.143.2554,094
21820.13.144.0/2020.13.144.1 to 20.13.159.25420.13.159.2554,094
21920.13.160.0/2020.13.160.1 to 20.13.175.25420.13.175.2554,094
22020.13.176.0/2020.13.176.1 to 20.13.191.25420.13.191.2554,094
22120.13.192.0/2020.13.192.1 to 20.13.207.25420.13.207.2554,094
22220.13.208.0/2020.13.208.1 to 20.13.223.25420.13.223.2554,094
22320.13.224.0/2020.13.224.1 to 20.13.239.25420.13.239.2554,094
22420.13.240.0/2020.13.240.1 to 20.13.255.25420.13.255.2554,094
22520.14.0.0/2020.14.0.1 to 20.14.15.25420.14.15.2554,094
22620.14.16.0/2020.14.16.1 to 20.14.31.25420.14.31.2554,094
22720.14.32.0/2020.14.32.1 to 20.14.47.25420.14.47.2554,094
22820.14.48.0/2020.14.48.1 to 20.14.63.25420.14.63.2554,094
22920.14.64.0/2020.14.64.1 to 20.14.79.25420.14.79.2554,094
23020.14.80.0/2020.14.80.1 to 20.14.95.25420.14.95.2554,094
23120.14.96.0/2020.14.96.1 to 20.14.111.25420.14.111.2554,094
23220.14.112.0/2020.14.112.1 to 20.14.127.25420.14.127.2554,094
23320.14.128.0/2020.14.128.1 to 20.14.143.25420.14.143.2554,094
23420.14.144.0/2020.14.144.1 to 20.14.159.25420.14.159.2554,094
23520.14.160.0/2020.14.160.1 to 20.14.175.25420.14.175.2554,094
23620.14.176.0/2020.14.176.1 to 20.14.191.25420.14.191.2554,094
23720.14.192.0/2020.14.192.1 to 20.14.207.25420.14.207.2554,094
23820.14.208.0/2020.14.208.1 to 20.14.223.25420.14.223.2554,094
23920.14.224.0/2020.14.224.1 to 20.14.239.25420.14.239.2554,094
24020.14.240.0/2020.14.240.1 to 20.14.255.25420.14.255.2554,094
24120.15.0.0/2020.15.0.1 to 20.15.15.25420.15.15.2554,094
24220.15.16.0/2020.15.16.1 to 20.15.31.25420.15.31.2554,094
24320.15.32.0/2020.15.32.1 to 20.15.47.25420.15.47.2554,094
24420.15.48.0/2020.15.48.1 to 20.15.63.25420.15.63.2554,094
24520.15.64.0/2020.15.64.1 to 20.15.79.25420.15.79.2554,094
24620.15.80.0/2020.15.80.1 to 20.15.95.25420.15.95.2554,094
24720.15.96.0/2020.15.96.1 to 20.15.111.25420.15.111.2554,094
24820.15.112.0/2020.15.112.1 to 20.15.127.25420.15.127.2554,094
24920.15.128.0/2020.15.128.1 to 20.15.143.25420.15.143.2554,094
25020.15.144.0/2020.15.144.1 to 20.15.159.25420.15.159.2554,094
25120.15.160.0/2020.15.160.1 to 20.15.175.25420.15.175.2554,094
25220.15.176.0/2020.15.176.1 to 20.15.191.25420.15.191.2554,094
25320.15.192.0/2020.15.192.1 to 20.15.207.25420.15.207.2554,094
25420.15.208.0/2020.15.208.1 to 20.15.223.25420.15.223.2554,094
25520.15.224.0/2020.15.224.1 to 20.15.239.25420.15.239.2554,094
25620.15.240.0/2020.15.240.1 to 20.15.255.25420.15.255.2554,094

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.