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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/19
/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 1,024 subnets of /19; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
120.0.0.0/1920.0.0.1 to 20.0.31.25420.0.31.2558,190
220.0.32.0/1920.0.32.1 to 20.0.63.25420.0.63.2558,190
320.0.64.0/1920.0.64.1 to 20.0.95.25420.0.95.2558,190
420.0.96.0/1920.0.96.1 to 20.0.127.25420.0.127.2558,190
520.0.128.0/1920.0.128.1 to 20.0.159.25420.0.159.2558,190
620.0.160.0/1920.0.160.1 to 20.0.191.25420.0.191.2558,190
720.0.192.0/1920.0.192.1 to 20.0.223.25420.0.223.2558,190
820.0.224.0/1920.0.224.1 to 20.0.255.25420.0.255.2558,190
920.1.0.0/1920.1.0.1 to 20.1.31.25420.1.31.2558,190
1020.1.32.0/1920.1.32.1 to 20.1.63.25420.1.63.2558,190
1120.1.64.0/1920.1.64.1 to 20.1.95.25420.1.95.2558,190
1220.1.96.0/1920.1.96.1 to 20.1.127.25420.1.127.2558,190
1320.1.128.0/1920.1.128.1 to 20.1.159.25420.1.159.2558,190
1420.1.160.0/1920.1.160.1 to 20.1.191.25420.1.191.2558,190
1520.1.192.0/1920.1.192.1 to 20.1.223.25420.1.223.2558,190
1620.1.224.0/1920.1.224.1 to 20.1.255.25420.1.255.2558,190
1720.2.0.0/1920.2.0.1 to 20.2.31.25420.2.31.2558,190
1820.2.32.0/1920.2.32.1 to 20.2.63.25420.2.63.2558,190
1920.2.64.0/1920.2.64.1 to 20.2.95.25420.2.95.2558,190
2020.2.96.0/1920.2.96.1 to 20.2.127.25420.2.127.2558,190
2120.2.128.0/1920.2.128.1 to 20.2.159.25420.2.159.2558,190
2220.2.160.0/1920.2.160.1 to 20.2.191.25420.2.191.2558,190
2320.2.192.0/1920.2.192.1 to 20.2.223.25420.2.223.2558,190
2420.2.224.0/1920.2.224.1 to 20.2.255.25420.2.255.2558,190
2520.3.0.0/1920.3.0.1 to 20.3.31.25420.3.31.2558,190
2620.3.32.0/1920.3.32.1 to 20.3.63.25420.3.63.2558,190
2720.3.64.0/1920.3.64.1 to 20.3.95.25420.3.95.2558,190
2820.3.96.0/1920.3.96.1 to 20.3.127.25420.3.127.2558,190
2920.3.128.0/1920.3.128.1 to 20.3.159.25420.3.159.2558,190
3020.3.160.0/1920.3.160.1 to 20.3.191.25420.3.191.2558,190
3120.3.192.0/1920.3.192.1 to 20.3.223.25420.3.223.2558,190
3220.3.224.0/1920.3.224.1 to 20.3.255.25420.3.255.2558,190
3320.4.0.0/1920.4.0.1 to 20.4.31.25420.4.31.2558,190
3420.4.32.0/1920.4.32.1 to 20.4.63.25420.4.63.2558,190
3520.4.64.0/1920.4.64.1 to 20.4.95.25420.4.95.2558,190
3620.4.96.0/1920.4.96.1 to 20.4.127.25420.4.127.2558,190
3720.4.128.0/1920.4.128.1 to 20.4.159.25420.4.159.2558,190
3820.4.160.0/1920.4.160.1 to 20.4.191.25420.4.191.2558,190
3920.4.192.0/1920.4.192.1 to 20.4.223.25420.4.223.2558,190
4020.4.224.0/1920.4.224.1 to 20.4.255.25420.4.255.2558,190
4120.5.0.0/1920.5.0.1 to 20.5.31.25420.5.31.2558,190
4220.5.32.0/1920.5.32.1 to 20.5.63.25420.5.63.2558,190
4320.5.64.0/1920.5.64.1 to 20.5.95.25420.5.95.2558,190
4420.5.96.0/1920.5.96.1 to 20.5.127.25420.5.127.2558,190
4520.5.128.0/1920.5.128.1 to 20.5.159.25420.5.159.2558,190
4620.5.160.0/1920.5.160.1 to 20.5.191.25420.5.191.2558,190
4720.5.192.0/1920.5.192.1 to 20.5.223.25420.5.223.2558,190
4820.5.224.0/1920.5.224.1 to 20.5.255.25420.5.255.2558,190
4920.6.0.0/1920.6.0.1 to 20.6.31.25420.6.31.2558,190
5020.6.32.0/1920.6.32.1 to 20.6.63.25420.6.63.2558,190
5120.6.64.0/1920.6.64.1 to 20.6.95.25420.6.95.2558,190
5220.6.96.0/1920.6.96.1 to 20.6.127.25420.6.127.2558,190
5320.6.128.0/1920.6.128.1 to 20.6.159.25420.6.159.2558,190
5420.6.160.0/1920.6.160.1 to 20.6.191.25420.6.191.2558,190
5520.6.192.0/1920.6.192.1 to 20.6.223.25420.6.223.2558,190
5620.6.224.0/1920.6.224.1 to 20.6.255.25420.6.255.2558,190
5720.7.0.0/1920.7.0.1 to 20.7.31.25420.7.31.2558,190
5820.7.32.0/1920.7.32.1 to 20.7.63.25420.7.63.2558,190
5920.7.64.0/1920.7.64.1 to 20.7.95.25420.7.95.2558,190
6020.7.96.0/1920.7.96.1 to 20.7.127.25420.7.127.2558,190
6120.7.128.0/1920.7.128.1 to 20.7.159.25420.7.159.2558,190
6220.7.160.0/1920.7.160.1 to 20.7.191.25420.7.191.2558,190
6320.7.192.0/1920.7.192.1 to 20.7.223.25420.7.223.2558,190
6420.7.224.0/1920.7.224.1 to 20.7.255.25420.7.255.2558,190
6520.8.0.0/1920.8.0.1 to 20.8.31.25420.8.31.2558,190
6620.8.32.0/1920.8.32.1 to 20.8.63.25420.8.63.2558,190
6720.8.64.0/1920.8.64.1 to 20.8.95.25420.8.95.2558,190
6820.8.96.0/1920.8.96.1 to 20.8.127.25420.8.127.2558,190
6920.8.128.0/1920.8.128.1 to 20.8.159.25420.8.159.2558,190
7020.8.160.0/1920.8.160.1 to 20.8.191.25420.8.191.2558,190
7120.8.192.0/1920.8.192.1 to 20.8.223.25420.8.223.2558,190
7220.8.224.0/1920.8.224.1 to 20.8.255.25420.8.255.2558,190
7320.9.0.0/1920.9.0.1 to 20.9.31.25420.9.31.2558,190
7420.9.32.0/1920.9.32.1 to 20.9.63.25420.9.63.2558,190
7520.9.64.0/1920.9.64.1 to 20.9.95.25420.9.95.2558,190
7620.9.96.0/1920.9.96.1 to 20.9.127.25420.9.127.2558,190
7720.9.128.0/1920.9.128.1 to 20.9.159.25420.9.159.2558,190
7820.9.160.0/1920.9.160.1 to 20.9.191.25420.9.191.2558,190
7920.9.192.0/1920.9.192.1 to 20.9.223.25420.9.223.2558,190
8020.9.224.0/1920.9.224.1 to 20.9.255.25420.9.255.2558,190
8120.10.0.0/1920.10.0.1 to 20.10.31.25420.10.31.2558,190
8220.10.32.0/1920.10.32.1 to 20.10.63.25420.10.63.2558,190
8320.10.64.0/1920.10.64.1 to 20.10.95.25420.10.95.2558,190
8420.10.96.0/1920.10.96.1 to 20.10.127.25420.10.127.2558,190
8520.10.128.0/1920.10.128.1 to 20.10.159.25420.10.159.2558,190
8620.10.160.0/1920.10.160.1 to 20.10.191.25420.10.191.2558,190
8720.10.192.0/1920.10.192.1 to 20.10.223.25420.10.223.2558,190
8820.10.224.0/1920.10.224.1 to 20.10.255.25420.10.255.2558,190
8920.11.0.0/1920.11.0.1 to 20.11.31.25420.11.31.2558,190
9020.11.32.0/1920.11.32.1 to 20.11.63.25420.11.63.2558,190
9120.11.64.0/1920.11.64.1 to 20.11.95.25420.11.95.2558,190
9220.11.96.0/1920.11.96.1 to 20.11.127.25420.11.127.2558,190
9320.11.128.0/1920.11.128.1 to 20.11.159.25420.11.159.2558,190
9420.11.160.0/1920.11.160.1 to 20.11.191.25420.11.191.2558,190
9520.11.192.0/1920.11.192.1 to 20.11.223.25420.11.223.2558,190
9620.11.224.0/1920.11.224.1 to 20.11.255.25420.11.255.2558,190
9720.12.0.0/1920.12.0.1 to 20.12.31.25420.12.31.2558,190
9820.12.32.0/1920.12.32.1 to 20.12.63.25420.12.63.2558,190
9920.12.64.0/1920.12.64.1 to 20.12.95.25420.12.95.2558,190
10020.12.96.0/1920.12.96.1 to 20.12.127.25420.12.127.2558,190
10120.12.128.0/1920.12.128.1 to 20.12.159.25420.12.159.2558,190
10220.12.160.0/1920.12.160.1 to 20.12.191.25420.12.191.2558,190
10320.12.192.0/1920.12.192.1 to 20.12.223.25420.12.223.2558,190
10420.12.224.0/1920.12.224.1 to 20.12.255.25420.12.255.2558,190
10520.13.0.0/1920.13.0.1 to 20.13.31.25420.13.31.2558,190
10620.13.32.0/1920.13.32.1 to 20.13.63.25420.13.63.2558,190
10720.13.64.0/1920.13.64.1 to 20.13.95.25420.13.95.2558,190
10820.13.96.0/1920.13.96.1 to 20.13.127.25420.13.127.2558,190
10920.13.128.0/1920.13.128.1 to 20.13.159.25420.13.159.2558,190
11020.13.160.0/1920.13.160.1 to 20.13.191.25420.13.191.2558,190
11120.13.192.0/1920.13.192.1 to 20.13.223.25420.13.223.2558,190
11220.13.224.0/1920.13.224.1 to 20.13.255.25420.13.255.2558,190
11320.14.0.0/1920.14.0.1 to 20.14.31.25420.14.31.2558,190
11420.14.32.0/1920.14.32.1 to 20.14.63.25420.14.63.2558,190
11520.14.64.0/1920.14.64.1 to 20.14.95.25420.14.95.2558,190
11620.14.96.0/1920.14.96.1 to 20.14.127.25420.14.127.2558,190
11720.14.128.0/1920.14.128.1 to 20.14.159.25420.14.159.2558,190
11820.14.160.0/1920.14.160.1 to 20.14.191.25420.14.191.2558,190
11920.14.192.0/1920.14.192.1 to 20.14.223.25420.14.223.2558,190
12020.14.224.0/1920.14.224.1 to 20.14.255.25420.14.255.2558,190
12120.15.0.0/1920.15.0.1 to 20.15.31.25420.15.31.2558,190
12220.15.32.0/1920.15.32.1 to 20.15.63.25420.15.63.2558,190
12320.15.64.0/1920.15.64.1 to 20.15.95.25420.15.95.2558,190
12420.15.96.0/1920.15.96.1 to 20.15.127.25420.15.127.2558,190
12520.15.128.0/1920.15.128.1 to 20.15.159.25420.15.159.2558,190
12620.15.160.0/1920.15.160.1 to 20.15.191.25420.15.191.2558,190
12720.15.192.0/1920.15.192.1 to 20.15.223.25420.15.223.2558,190
12820.15.224.0/1920.15.224.1 to 20.15.255.25420.15.255.2558,190
12920.16.0.0/1920.16.0.1 to 20.16.31.25420.16.31.2558,190
13020.16.32.0/1920.16.32.1 to 20.16.63.25420.16.63.2558,190
13120.16.64.0/1920.16.64.1 to 20.16.95.25420.16.95.2558,190
13220.16.96.0/1920.16.96.1 to 20.16.127.25420.16.127.2558,190
13320.16.128.0/1920.16.128.1 to 20.16.159.25420.16.159.2558,190
13420.16.160.0/1920.16.160.1 to 20.16.191.25420.16.191.2558,190
13520.16.192.0/1920.16.192.1 to 20.16.223.25420.16.223.2558,190
13620.16.224.0/1920.16.224.1 to 20.16.255.25420.16.255.2558,190
13720.17.0.0/1920.17.0.1 to 20.17.31.25420.17.31.2558,190
13820.17.32.0/1920.17.32.1 to 20.17.63.25420.17.63.2558,190
13920.17.64.0/1920.17.64.1 to 20.17.95.25420.17.95.2558,190
14020.17.96.0/1920.17.96.1 to 20.17.127.25420.17.127.2558,190
14120.17.128.0/1920.17.128.1 to 20.17.159.25420.17.159.2558,190
14220.17.160.0/1920.17.160.1 to 20.17.191.25420.17.191.2558,190
14320.17.192.0/1920.17.192.1 to 20.17.223.25420.17.223.2558,190
14420.17.224.0/1920.17.224.1 to 20.17.255.25420.17.255.2558,190
14520.18.0.0/1920.18.0.1 to 20.18.31.25420.18.31.2558,190
14620.18.32.0/1920.18.32.1 to 20.18.63.25420.18.63.2558,190
14720.18.64.0/1920.18.64.1 to 20.18.95.25420.18.95.2558,190
14820.18.96.0/1920.18.96.1 to 20.18.127.25420.18.127.2558,190
14920.18.128.0/1920.18.128.1 to 20.18.159.25420.18.159.2558,190
15020.18.160.0/1920.18.160.1 to 20.18.191.25420.18.191.2558,190
15120.18.192.0/1920.18.192.1 to 20.18.223.25420.18.223.2558,190
15220.18.224.0/1920.18.224.1 to 20.18.255.25420.18.255.2558,190
15320.19.0.0/1920.19.0.1 to 20.19.31.25420.19.31.2558,190
15420.19.32.0/1920.19.32.1 to 20.19.63.25420.19.63.2558,190
15520.19.64.0/1920.19.64.1 to 20.19.95.25420.19.95.2558,190
15620.19.96.0/1920.19.96.1 to 20.19.127.25420.19.127.2558,190
15720.19.128.0/1920.19.128.1 to 20.19.159.25420.19.159.2558,190
15820.19.160.0/1920.19.160.1 to 20.19.191.25420.19.191.2558,190
15920.19.192.0/1920.19.192.1 to 20.19.223.25420.19.223.2558,190
16020.19.224.0/1920.19.224.1 to 20.19.255.25420.19.255.2558,190
16120.20.0.0/1920.20.0.1 to 20.20.31.25420.20.31.2558,190
16220.20.32.0/1920.20.32.1 to 20.20.63.25420.20.63.2558,190
16320.20.64.0/1920.20.64.1 to 20.20.95.25420.20.95.2558,190
16420.20.96.0/1920.20.96.1 to 20.20.127.25420.20.127.2558,190
16520.20.128.0/1920.20.128.1 to 20.20.159.25420.20.159.2558,190
16620.20.160.0/1920.20.160.1 to 20.20.191.25420.20.191.2558,190
16720.20.192.0/1920.20.192.1 to 20.20.223.25420.20.223.2558,190
16820.20.224.0/1920.20.224.1 to 20.20.255.25420.20.255.2558,190
16920.21.0.0/1920.21.0.1 to 20.21.31.25420.21.31.2558,190
17020.21.32.0/1920.21.32.1 to 20.21.63.25420.21.63.2558,190
17120.21.64.0/1920.21.64.1 to 20.21.95.25420.21.95.2558,190
17220.21.96.0/1920.21.96.1 to 20.21.127.25420.21.127.2558,190
17320.21.128.0/1920.21.128.1 to 20.21.159.25420.21.159.2558,190
17420.21.160.0/1920.21.160.1 to 20.21.191.25420.21.191.2558,190
17520.21.192.0/1920.21.192.1 to 20.21.223.25420.21.223.2558,190
17620.21.224.0/1920.21.224.1 to 20.21.255.25420.21.255.2558,190
17720.22.0.0/1920.22.0.1 to 20.22.31.25420.22.31.2558,190
17820.22.32.0/1920.22.32.1 to 20.22.63.25420.22.63.2558,190
17920.22.64.0/1920.22.64.1 to 20.22.95.25420.22.95.2558,190
18020.22.96.0/1920.22.96.1 to 20.22.127.25420.22.127.2558,190
18120.22.128.0/1920.22.128.1 to 20.22.159.25420.22.159.2558,190
18220.22.160.0/1920.22.160.1 to 20.22.191.25420.22.191.2558,190
18320.22.192.0/1920.22.192.1 to 20.22.223.25420.22.223.2558,190
18420.22.224.0/1920.22.224.1 to 20.22.255.25420.22.255.2558,190
18520.23.0.0/1920.23.0.1 to 20.23.31.25420.23.31.2558,190
18620.23.32.0/1920.23.32.1 to 20.23.63.25420.23.63.2558,190
18720.23.64.0/1920.23.64.1 to 20.23.95.25420.23.95.2558,190
18820.23.96.0/1920.23.96.1 to 20.23.127.25420.23.127.2558,190
18920.23.128.0/1920.23.128.1 to 20.23.159.25420.23.159.2558,190
19020.23.160.0/1920.23.160.1 to 20.23.191.25420.23.191.2558,190
19120.23.192.0/1920.23.192.1 to 20.23.223.25420.23.223.2558,190
19220.23.224.0/1920.23.224.1 to 20.23.255.25420.23.255.2558,190
19320.24.0.0/1920.24.0.1 to 20.24.31.25420.24.31.2558,190
19420.24.32.0/1920.24.32.1 to 20.24.63.25420.24.63.2558,190
19520.24.64.0/1920.24.64.1 to 20.24.95.25420.24.95.2558,190
19620.24.96.0/1920.24.96.1 to 20.24.127.25420.24.127.2558,190
19720.24.128.0/1920.24.128.1 to 20.24.159.25420.24.159.2558,190
19820.24.160.0/1920.24.160.1 to 20.24.191.25420.24.191.2558,190
19920.24.192.0/1920.24.192.1 to 20.24.223.25420.24.223.2558,190
20020.24.224.0/1920.24.224.1 to 20.24.255.25420.24.255.2558,190
20120.25.0.0/1920.25.0.1 to 20.25.31.25420.25.31.2558,190
20220.25.32.0/1920.25.32.1 to 20.25.63.25420.25.63.2558,190
20320.25.64.0/1920.25.64.1 to 20.25.95.25420.25.95.2558,190
20420.25.96.0/1920.25.96.1 to 20.25.127.25420.25.127.2558,190
20520.25.128.0/1920.25.128.1 to 20.25.159.25420.25.159.2558,190
20620.25.160.0/1920.25.160.1 to 20.25.191.25420.25.191.2558,190
20720.25.192.0/1920.25.192.1 to 20.25.223.25420.25.223.2558,190
20820.25.224.0/1920.25.224.1 to 20.25.255.25420.25.255.2558,190
20920.26.0.0/1920.26.0.1 to 20.26.31.25420.26.31.2558,190
21020.26.32.0/1920.26.32.1 to 20.26.63.25420.26.63.2558,190
21120.26.64.0/1920.26.64.1 to 20.26.95.25420.26.95.2558,190
21220.26.96.0/1920.26.96.1 to 20.26.127.25420.26.127.2558,190
21320.26.128.0/1920.26.128.1 to 20.26.159.25420.26.159.2558,190
21420.26.160.0/1920.26.160.1 to 20.26.191.25420.26.191.2558,190
21520.26.192.0/1920.26.192.1 to 20.26.223.25420.26.223.2558,190
21620.26.224.0/1920.26.224.1 to 20.26.255.25420.26.255.2558,190
21720.27.0.0/1920.27.0.1 to 20.27.31.25420.27.31.2558,190
21820.27.32.0/1920.27.32.1 to 20.27.63.25420.27.63.2558,190
21920.27.64.0/1920.27.64.1 to 20.27.95.25420.27.95.2558,190
22020.27.96.0/1920.27.96.1 to 20.27.127.25420.27.127.2558,190
22120.27.128.0/1920.27.128.1 to 20.27.159.25420.27.159.2558,190
22220.27.160.0/1920.27.160.1 to 20.27.191.25420.27.191.2558,190
22320.27.192.0/1920.27.192.1 to 20.27.223.25420.27.223.2558,190
22420.27.224.0/1920.27.224.1 to 20.27.255.25420.27.255.2558,190
22520.28.0.0/1920.28.0.1 to 20.28.31.25420.28.31.2558,190
22620.28.32.0/1920.28.32.1 to 20.28.63.25420.28.63.2558,190
22720.28.64.0/1920.28.64.1 to 20.28.95.25420.28.95.2558,190
22820.28.96.0/1920.28.96.1 to 20.28.127.25420.28.127.2558,190
22920.28.128.0/1920.28.128.1 to 20.28.159.25420.28.159.2558,190
23020.28.160.0/1920.28.160.1 to 20.28.191.25420.28.191.2558,190
23120.28.192.0/1920.28.192.1 to 20.28.223.25420.28.223.2558,190
23220.28.224.0/1920.28.224.1 to 20.28.255.25420.28.255.2558,190
23320.29.0.0/1920.29.0.1 to 20.29.31.25420.29.31.2558,190
23420.29.32.0/1920.29.32.1 to 20.29.63.25420.29.63.2558,190
23520.29.64.0/1920.29.64.1 to 20.29.95.25420.29.95.2558,190
23620.29.96.0/1920.29.96.1 to 20.29.127.25420.29.127.2558,190
23720.29.128.0/1920.29.128.1 to 20.29.159.25420.29.159.2558,190
23820.29.160.0/1920.29.160.1 to 20.29.191.25420.29.191.2558,190
23920.29.192.0/1920.29.192.1 to 20.29.223.25420.29.223.2558,190
24020.29.224.0/1920.29.224.1 to 20.29.255.25420.29.255.2558,190
24120.30.0.0/1920.30.0.1 to 20.30.31.25420.30.31.2558,190
24220.30.32.0/1920.30.32.1 to 20.30.63.25420.30.63.2558,190
24320.30.64.0/1920.30.64.1 to 20.30.95.25420.30.95.2558,190
24420.30.96.0/1920.30.96.1 to 20.30.127.25420.30.127.2558,190
24520.30.128.0/1920.30.128.1 to 20.30.159.25420.30.159.2558,190
24620.30.160.0/1920.30.160.1 to 20.30.191.25420.30.191.2558,190
24720.30.192.0/1920.30.192.1 to 20.30.223.25420.30.223.2558,190
24820.30.224.0/1920.30.224.1 to 20.30.255.25420.30.255.2558,190
24920.31.0.0/1920.31.0.1 to 20.31.31.25420.31.31.2558,190
25020.31.32.0/1920.31.32.1 to 20.31.63.25420.31.63.2558,190
25120.31.64.0/1920.31.64.1 to 20.31.95.25420.31.95.2558,190
25220.31.96.0/1920.31.96.1 to 20.31.127.25420.31.127.2558,190
25320.31.128.0/1920.31.128.1 to 20.31.159.25420.31.159.2558,190
25420.31.160.0/1920.31.160.1 to 20.31.191.25420.31.191.2558,190
25520.31.192.0/1920.31.192.1 to 20.31.223.25420.31.223.2558,190
25620.31.224.0/1920.31.224.1 to 20.31.255.25420.31.255.2558,190

IPv4 CIDR reference (/0 to /32)

IPv4 prefix lengths
PrefixSubnet maskWildcardAddressesUsable hostsSizeTypical use
/00.0.0.0255.255.255.2554,294,967,2964,294,967,29416,777,216 × /24
/1128.0.0.0127.255.255.2552,147,483,6482,147,483,6468,388,608 × /24
/2192.0.0.063.255.255.2551,073,741,8241,073,741,8224,194,304 × /24
/3224.0.0.031.255.255.255536,870,912536,870,9102,097,152 × /24
/4240.0.0.015.255.255.255268,435,456268,435,4541,048,576 × /24
/5248.0.0.07.255.255.255134,217,728134,217,726524,288 × /24
/6252.0.0.03.255.255.25567,108,86467,108,862262,144 × /24
/7254.0.0.01.255.255.25533,554,43233,554,430131,072 × /24
/8255.0.0.00.255.255.25516,777,21616,777,21465,536 × /24Old class A; 10.0.0.0/8
/9255.128.0.00.127.255.2558,388,6088,388,60632,768 × /24
/10255.192.0.00.63.255.2554,194,3044,194,30216,384 × /24
/11255.224.0.00.31.255.2552,097,1522,097,1508,192 × /24
/12255.240.0.00.15.255.2551,048,5761,048,5744,096 × /24172.16.0.0/12
/13255.248.0.00.7.255.255524,288524,2862,048 × /24
/14255.252.0.00.3.255.255262,144262,1421,024 × /24
/15255.254.0.00.1.255.255131,072131,070512 × /24
/16255.255.0.00.0.255.25565,53665,534256 × /24Old class B; 192.168.0.0/16
/17255.255.128.00.0.127.25532,76832,766128 × /24
/18255.255.192.00.0.63.25516,38416,38264 × /24
/19255.255.224.00.0.31.2558,1928,19032 × /24
/20255.255.240.00.0.15.2554,0964,09416 × /24
/21255.255.248.00.0.7.2552,0482,0468 × /24
/22255.255.252.00.0.3.2551,0241,0224 × /24Large office or guest Wi-Fi (1,022 hosts)
/23255.255.254.00.0.1.2555125102 × /24Larger office LAN (510 hosts)
/24255.255.255.00.0.0.2552562541 × /24Typical office LAN (old class C)
/25255.255.255.1280.0.0.1271281261/2 of a /24Smaller LAN or VLAN
/26255.255.255.1920.0.0.6364621/4 of a /24Smaller LAN or VLAN
/27255.255.255.2240.0.0.3132301/8 of a /24Small VLAN, phones, cameras
/28255.255.255.2400.0.0.1516141/16 of a /24Small VLAN, phones, cameras
/29255.255.255.2480.0.0.7861/32 of a /24Small fixed public block (5 usable)
/30255.255.255.2520.0.0.3421/64 of a /24Point-to-point (old style)
/31255.255.255.2540.0.0.1221/128 of a /24Point-to-point link (RFC 3021)
/32255.255.255.2550.0.0.0111/256 of a /24One host

IPv6 prefix reference

IPv6 prefix lengths
PrefixAddresses/64 LANs/48 sitesNibbleTypical use
/342,535,295,865,117,307,932,921,825,928,971,026,432 (2^125)2,305,843,009,213,693,95235,184,372,088,832NoAll global unicast (2000::/3)
/165,192,296,858,534,827,628,530,496,329,220,096 (2^112)281,474,976,710,6564,294,967,296Yes
/20324,518,553,658,426,726,783,156,020,576,256 (2^108)17,592,186,044,416268,435,456YesLarge provider allocation (RIPE minimum for some)
/29633,825,300,114,114,700,748,351,602,688 (2^99)34,359,738,368524,288NoRIPE allocation to a provider (often)
/3279,228,162,514,264,337,593,543,950,336 (2^96)4,294,967,29665,536YesProvider allocation (RIPE default)
/364,951,760,157,141,521,099,596,496,896 (2^92)268,435,4564,096Yes
/40309,485,009,821,345,068,724,781,056 (2^88)16,777,216256Yes
/4419,342,813,113,834,066,795,298,816 (2^84)1,048,57616Yes
/481,208,925,819,614,629,174,706,176 (2^80)65,5361YesOne site or organisation (RIPE PI / assignment)
/5275,557,863,725,914,323,419,136 (2^76)4,096Yes
/564,722,366,482,869,645,213,696 (2^72)256YesSmall site or home (common provider assignment)
/60295,147,905,179,352,825,856 (2^68)16YesSome home broadband (16 LANs)
/6418,446,744,073,709,551,616 (2^64)1YesOne LAN or VLAN (needed for SLAAC)
/7272,057,594,037,927,936 (2^56)1/256 of a /64Yes
/80281,474,976,710,656 (2^48)1/65,536 of a /64Yes
/964,294,967,2961/4,294,967,296 of a /64YesEmbeds an IPv4 address (NAT64)
/11265,5361/281,474,976,710,656 of a /64Yes
/1202561/72,057,594,037,927,936 of a /64Yes
/124161/1,152,921,504,606,846,976 of a /64Yes
/12641/4,611,686,018,427,387,904 of a /64No
/12721/9,223,372,036,854,775,808 of a /64NoPoint-to-point link (RFC 6164)
/12811/18,446,744,073,709,551,616 of a /64YesOne host or loopback

Private and special ranges

IPv4

Special-purpose ranges
RangeNameWhat it is
255.255.255.255/32Limited broadcastEvery host on the local network
0.0.0.0/8This networkNot routed; 0.0.0.0 means "any address" in settings
10.0.0.0/8Private (RFC 1918)Office and home networks; not routed on the internet
100.64.0.0/10Shared address space (CGNAT)Used by providers behind carrier-grade NAT (RFC 6598)
127.0.0.0/8LoopbackThis computer
169.254.0.0/16Link-local (APIPA)Self-assigned when no DHCP server answers
172.16.0.0/12Private (RFC 1918)Office and home networks; not routed on the internet
192.0.0.0/24IETF protocol assignmentsSpecial uses such as DS-Lite
192.0.2.0/24Documentation (TEST-NET-1)For examples; never used on a network
192.88.99.0/246to4 relay (deprecated)Formerly anycast for 6to4
192.168.0.0/16Private (RFC 1918)Office and home networks; not routed on the internet
198.18.0.0/15BenchmarkingNetwork equipment testing (RFC 2544)
198.51.100.0/24Documentation (TEST-NET-2)For examples; never used on a network
203.0.113.0/24Documentation (TEST-NET-3)For examples; never used on a network
224.0.0.0/4MulticastOne-to-many traffic, such as IPTV and routing protocols
240.0.0.0/4ReservedFuture use; not usable on most systems

IPv6

Special-purpose ranges
RangeNameWhat it is
::/128UnspecifiedNo address; :: means "any address" in settings
::1/128LoopbackThis computer
::ffff:0:0/96IPv4-mappedAn IPv4 address written as IPv6
64:ff9b::/96NAT64IPv4 addresses reached through a NAT64 gateway
100::/64Discard onlyTraffic sent here is dropped (RFC 6666)
2001:db8::/32DocumentationFor examples; never used on a network
2001::/32TeredoIPv6 tunnelled over IPv4 UDP
2002::/166to4IPv6 tunnelled over IPv4 (largely retired)
3fff::/20DocumentationFor examples (RFC 9637)
fc00::/7Unique local (ULA)Private IPv6, like RFC 1918; usually fd00::/8
fe80::/10Link-localEvery IPv6 interface has one; not routed
ff00::/8MulticastOne-to-many traffic; replaces broadcast
2000::/3Global unicastPublic internet addresses

About this tool

A network is written as an address and a prefix length, such as 192.168.1.0/24: the first 24 bits name the network and the rest number the devices on it. The calculator works out where the network starts and ends, how many devices it holds, its subnet and wildcard masks, and the reverse DNS zone to ask your provider for.

It also splits a network into equal smaller ones (one per VLAN or site), turns a range of addresses into the fewest CIDR blocks for a firewall rule, and lists every IPv4 prefix length and the common IPv6 ones in reference tables.

Common questions

Why are two addresses lost in every IPv4 subnet?

The first address names the network and the last is the broadcast address, so a /24 has 256 addresses but 254 for devices. A /31 (a link between two routers) and a /32 (one host) are the exceptions.

What size of IPv6 network should a LAN use?

Always /64. Devices pick their own address within it (SLAAC), which needs the full 64 bits. A site usually gets a /48 or /56 from its provider, which holds 65,536 or 256 LANs.

What is a wildcard mask?

The subnet mask turned inside out: 255.255.255.0 becomes 0.0.0.255. Cisco access lists and OSPF use it to say which bits must match.

Which ranges can I use inside an office?

IPv4: 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16. IPv6: unique local addresses from fd00::/8, though most networks use the public prefix from their provider.