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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.

Network40.128.0.0/9
Usable hosts8,388,606
Subnet mask255.128.0.0
Addresses8,388,608
Network address
40.128.0.0
Broadcast address
40.255.255.255
First usable
40.128.0.1
Last usable
40.255.255.254
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 28800000 · Integer 679477248 to 687865855
Reverse DNS zones
128.40.in-addr.arpa
129.40.in-addr.arpa
130.40.in-addr.arpa
131.40.in-addr.arpa
132.40.in-addr.arpa
133.40.in-addr.arpa
134.40.in-addr.arpa
135.40.in-addr.arpa
136.40.in-addr.arpa
137.40.in-addr.arpa
138.40.in-addr.arpa
139.40.in-addr.arpa
140.40.in-addr.arpa
141.40.in-addr.arpa
142.40.in-addr.arpa
143.40.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
Address00101000.10000000.00000000.0000000040.128.0.0
Subnet mask11111111.10000000.00000000.00000000255.128.0.0
Network00101000.10000000.00000000.0000000040.128.0.0
Broadcast00101000.11111111.11111111.1111111140.255.255.255
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)

40.128.0.0/9 makes 1,024 subnets of /19; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
140.128.0.0/1940.128.0.1 to 40.128.31.25440.128.31.2558,190
240.128.32.0/1940.128.32.1 to 40.128.63.25440.128.63.2558,190
340.128.64.0/1940.128.64.1 to 40.128.95.25440.128.95.2558,190
440.128.96.0/1940.128.96.1 to 40.128.127.25440.128.127.2558,190
540.128.128.0/1940.128.128.1 to 40.128.159.25440.128.159.2558,190
640.128.160.0/1940.128.160.1 to 40.128.191.25440.128.191.2558,190
740.128.192.0/1940.128.192.1 to 40.128.223.25440.128.223.2558,190
840.128.224.0/1940.128.224.1 to 40.128.255.25440.128.255.2558,190
940.129.0.0/1940.129.0.1 to 40.129.31.25440.129.31.2558,190
1040.129.32.0/1940.129.32.1 to 40.129.63.25440.129.63.2558,190
1140.129.64.0/1940.129.64.1 to 40.129.95.25440.129.95.2558,190
1240.129.96.0/1940.129.96.1 to 40.129.127.25440.129.127.2558,190
1340.129.128.0/1940.129.128.1 to 40.129.159.25440.129.159.2558,190
1440.129.160.0/1940.129.160.1 to 40.129.191.25440.129.191.2558,190
1540.129.192.0/1940.129.192.1 to 40.129.223.25440.129.223.2558,190
1640.129.224.0/1940.129.224.1 to 40.129.255.25440.129.255.2558,190
1740.130.0.0/1940.130.0.1 to 40.130.31.25440.130.31.2558,190
1840.130.32.0/1940.130.32.1 to 40.130.63.25440.130.63.2558,190
1940.130.64.0/1940.130.64.1 to 40.130.95.25440.130.95.2558,190
2040.130.96.0/1940.130.96.1 to 40.130.127.25440.130.127.2558,190
2140.130.128.0/1940.130.128.1 to 40.130.159.25440.130.159.2558,190
2240.130.160.0/1940.130.160.1 to 40.130.191.25440.130.191.2558,190
2340.130.192.0/1940.130.192.1 to 40.130.223.25440.130.223.2558,190
2440.130.224.0/1940.130.224.1 to 40.130.255.25440.130.255.2558,190
2540.131.0.0/1940.131.0.1 to 40.131.31.25440.131.31.2558,190
2640.131.32.0/1940.131.32.1 to 40.131.63.25440.131.63.2558,190
2740.131.64.0/1940.131.64.1 to 40.131.95.25440.131.95.2558,190
2840.131.96.0/1940.131.96.1 to 40.131.127.25440.131.127.2558,190
2940.131.128.0/1940.131.128.1 to 40.131.159.25440.131.159.2558,190
3040.131.160.0/1940.131.160.1 to 40.131.191.25440.131.191.2558,190
3140.131.192.0/1940.131.192.1 to 40.131.223.25440.131.223.2558,190
3240.131.224.0/1940.131.224.1 to 40.131.255.25440.131.255.2558,190
3340.132.0.0/1940.132.0.1 to 40.132.31.25440.132.31.2558,190
3440.132.32.0/1940.132.32.1 to 40.132.63.25440.132.63.2558,190
3540.132.64.0/1940.132.64.1 to 40.132.95.25440.132.95.2558,190
3640.132.96.0/1940.132.96.1 to 40.132.127.25440.132.127.2558,190
3740.132.128.0/1940.132.128.1 to 40.132.159.25440.132.159.2558,190
3840.132.160.0/1940.132.160.1 to 40.132.191.25440.132.191.2558,190
3940.132.192.0/1940.132.192.1 to 40.132.223.25440.132.223.2558,190
4040.132.224.0/1940.132.224.1 to 40.132.255.25440.132.255.2558,190
4140.133.0.0/1940.133.0.1 to 40.133.31.25440.133.31.2558,190
4240.133.32.0/1940.133.32.1 to 40.133.63.25440.133.63.2558,190
4340.133.64.0/1940.133.64.1 to 40.133.95.25440.133.95.2558,190
4440.133.96.0/1940.133.96.1 to 40.133.127.25440.133.127.2558,190
4540.133.128.0/1940.133.128.1 to 40.133.159.25440.133.159.2558,190
4640.133.160.0/1940.133.160.1 to 40.133.191.25440.133.191.2558,190
4740.133.192.0/1940.133.192.1 to 40.133.223.25440.133.223.2558,190
4840.133.224.0/1940.133.224.1 to 40.133.255.25440.133.255.2558,190
4940.134.0.0/1940.134.0.1 to 40.134.31.25440.134.31.2558,190
5040.134.32.0/1940.134.32.1 to 40.134.63.25440.134.63.2558,190
5140.134.64.0/1940.134.64.1 to 40.134.95.25440.134.95.2558,190
5240.134.96.0/1940.134.96.1 to 40.134.127.25440.134.127.2558,190
5340.134.128.0/1940.134.128.1 to 40.134.159.25440.134.159.2558,190
5440.134.160.0/1940.134.160.1 to 40.134.191.25440.134.191.2558,190
5540.134.192.0/1940.134.192.1 to 40.134.223.25440.134.223.2558,190
5640.134.224.0/1940.134.224.1 to 40.134.255.25440.134.255.2558,190
5740.135.0.0/1940.135.0.1 to 40.135.31.25440.135.31.2558,190
5840.135.32.0/1940.135.32.1 to 40.135.63.25440.135.63.2558,190
5940.135.64.0/1940.135.64.1 to 40.135.95.25440.135.95.2558,190
6040.135.96.0/1940.135.96.1 to 40.135.127.25440.135.127.2558,190
6140.135.128.0/1940.135.128.1 to 40.135.159.25440.135.159.2558,190
6240.135.160.0/1940.135.160.1 to 40.135.191.25440.135.191.2558,190
6340.135.192.0/1940.135.192.1 to 40.135.223.25440.135.223.2558,190
6440.135.224.0/1940.135.224.1 to 40.135.255.25440.135.255.2558,190
6540.136.0.0/1940.136.0.1 to 40.136.31.25440.136.31.2558,190
6640.136.32.0/1940.136.32.1 to 40.136.63.25440.136.63.2558,190
6740.136.64.0/1940.136.64.1 to 40.136.95.25440.136.95.2558,190
6840.136.96.0/1940.136.96.1 to 40.136.127.25440.136.127.2558,190
6940.136.128.0/1940.136.128.1 to 40.136.159.25440.136.159.2558,190
7040.136.160.0/1940.136.160.1 to 40.136.191.25440.136.191.2558,190
7140.136.192.0/1940.136.192.1 to 40.136.223.25440.136.223.2558,190
7240.136.224.0/1940.136.224.1 to 40.136.255.25440.136.255.2558,190
7340.137.0.0/1940.137.0.1 to 40.137.31.25440.137.31.2558,190
7440.137.32.0/1940.137.32.1 to 40.137.63.25440.137.63.2558,190
7540.137.64.0/1940.137.64.1 to 40.137.95.25440.137.95.2558,190
7640.137.96.0/1940.137.96.1 to 40.137.127.25440.137.127.2558,190
7740.137.128.0/1940.137.128.1 to 40.137.159.25440.137.159.2558,190
7840.137.160.0/1940.137.160.1 to 40.137.191.25440.137.191.2558,190
7940.137.192.0/1940.137.192.1 to 40.137.223.25440.137.223.2558,190
8040.137.224.0/1940.137.224.1 to 40.137.255.25440.137.255.2558,190
8140.138.0.0/1940.138.0.1 to 40.138.31.25440.138.31.2558,190
8240.138.32.0/1940.138.32.1 to 40.138.63.25440.138.63.2558,190
8340.138.64.0/1940.138.64.1 to 40.138.95.25440.138.95.2558,190
8440.138.96.0/1940.138.96.1 to 40.138.127.25440.138.127.2558,190
8540.138.128.0/1940.138.128.1 to 40.138.159.25440.138.159.2558,190
8640.138.160.0/1940.138.160.1 to 40.138.191.25440.138.191.2558,190
8740.138.192.0/1940.138.192.1 to 40.138.223.25440.138.223.2558,190
8840.138.224.0/1940.138.224.1 to 40.138.255.25440.138.255.2558,190
8940.139.0.0/1940.139.0.1 to 40.139.31.25440.139.31.2558,190
9040.139.32.0/1940.139.32.1 to 40.139.63.25440.139.63.2558,190
9140.139.64.0/1940.139.64.1 to 40.139.95.25440.139.95.2558,190
9240.139.96.0/1940.139.96.1 to 40.139.127.25440.139.127.2558,190
9340.139.128.0/1940.139.128.1 to 40.139.159.25440.139.159.2558,190
9440.139.160.0/1940.139.160.1 to 40.139.191.25440.139.191.2558,190
9540.139.192.0/1940.139.192.1 to 40.139.223.25440.139.223.2558,190
9640.139.224.0/1940.139.224.1 to 40.139.255.25440.139.255.2558,190
9740.140.0.0/1940.140.0.1 to 40.140.31.25440.140.31.2558,190
9840.140.32.0/1940.140.32.1 to 40.140.63.25440.140.63.2558,190
9940.140.64.0/1940.140.64.1 to 40.140.95.25440.140.95.2558,190
10040.140.96.0/1940.140.96.1 to 40.140.127.25440.140.127.2558,190
10140.140.128.0/1940.140.128.1 to 40.140.159.25440.140.159.2558,190
10240.140.160.0/1940.140.160.1 to 40.140.191.25440.140.191.2558,190
10340.140.192.0/1940.140.192.1 to 40.140.223.25440.140.223.2558,190
10440.140.224.0/1940.140.224.1 to 40.140.255.25440.140.255.2558,190
10540.141.0.0/1940.141.0.1 to 40.141.31.25440.141.31.2558,190
10640.141.32.0/1940.141.32.1 to 40.141.63.25440.141.63.2558,190
10740.141.64.0/1940.141.64.1 to 40.141.95.25440.141.95.2558,190
10840.141.96.0/1940.141.96.1 to 40.141.127.25440.141.127.2558,190
10940.141.128.0/1940.141.128.1 to 40.141.159.25440.141.159.2558,190
11040.141.160.0/1940.141.160.1 to 40.141.191.25440.141.191.2558,190
11140.141.192.0/1940.141.192.1 to 40.141.223.25440.141.223.2558,190
11240.141.224.0/1940.141.224.1 to 40.141.255.25440.141.255.2558,190
11340.142.0.0/1940.142.0.1 to 40.142.31.25440.142.31.2558,190
11440.142.32.0/1940.142.32.1 to 40.142.63.25440.142.63.2558,190
11540.142.64.0/1940.142.64.1 to 40.142.95.25440.142.95.2558,190
11640.142.96.0/1940.142.96.1 to 40.142.127.25440.142.127.2558,190
11740.142.128.0/1940.142.128.1 to 40.142.159.25440.142.159.2558,190
11840.142.160.0/1940.142.160.1 to 40.142.191.25440.142.191.2558,190
11940.142.192.0/1940.142.192.1 to 40.142.223.25440.142.223.2558,190
12040.142.224.0/1940.142.224.1 to 40.142.255.25440.142.255.2558,190
12140.143.0.0/1940.143.0.1 to 40.143.31.25440.143.31.2558,190
12240.143.32.0/1940.143.32.1 to 40.143.63.25440.143.63.2558,190
12340.143.64.0/1940.143.64.1 to 40.143.95.25440.143.95.2558,190
12440.143.96.0/1940.143.96.1 to 40.143.127.25440.143.127.2558,190
12540.143.128.0/1940.143.128.1 to 40.143.159.25440.143.159.2558,190
12640.143.160.0/1940.143.160.1 to 40.143.191.25440.143.191.2558,190
12740.143.192.0/1940.143.192.1 to 40.143.223.25440.143.223.2558,190
12840.143.224.0/1940.143.224.1 to 40.143.255.25440.143.255.2558,190
12940.144.0.0/1940.144.0.1 to 40.144.31.25440.144.31.2558,190
13040.144.32.0/1940.144.32.1 to 40.144.63.25440.144.63.2558,190
13140.144.64.0/1940.144.64.1 to 40.144.95.25440.144.95.2558,190
13240.144.96.0/1940.144.96.1 to 40.144.127.25440.144.127.2558,190
13340.144.128.0/1940.144.128.1 to 40.144.159.25440.144.159.2558,190
13440.144.160.0/1940.144.160.1 to 40.144.191.25440.144.191.2558,190
13540.144.192.0/1940.144.192.1 to 40.144.223.25440.144.223.2558,190
13640.144.224.0/1940.144.224.1 to 40.144.255.25440.144.255.2558,190
13740.145.0.0/1940.145.0.1 to 40.145.31.25440.145.31.2558,190
13840.145.32.0/1940.145.32.1 to 40.145.63.25440.145.63.2558,190
13940.145.64.0/1940.145.64.1 to 40.145.95.25440.145.95.2558,190
14040.145.96.0/1940.145.96.1 to 40.145.127.25440.145.127.2558,190
14140.145.128.0/1940.145.128.1 to 40.145.159.25440.145.159.2558,190
14240.145.160.0/1940.145.160.1 to 40.145.191.25440.145.191.2558,190
14340.145.192.0/1940.145.192.1 to 40.145.223.25440.145.223.2558,190
14440.145.224.0/1940.145.224.1 to 40.145.255.25440.145.255.2558,190
14540.146.0.0/1940.146.0.1 to 40.146.31.25440.146.31.2558,190
14640.146.32.0/1940.146.32.1 to 40.146.63.25440.146.63.2558,190
14740.146.64.0/1940.146.64.1 to 40.146.95.25440.146.95.2558,190
14840.146.96.0/1940.146.96.1 to 40.146.127.25440.146.127.2558,190
14940.146.128.0/1940.146.128.1 to 40.146.159.25440.146.159.2558,190
15040.146.160.0/1940.146.160.1 to 40.146.191.25440.146.191.2558,190
15140.146.192.0/1940.146.192.1 to 40.146.223.25440.146.223.2558,190
15240.146.224.0/1940.146.224.1 to 40.146.255.25440.146.255.2558,190
15340.147.0.0/1940.147.0.1 to 40.147.31.25440.147.31.2558,190
15440.147.32.0/1940.147.32.1 to 40.147.63.25440.147.63.2558,190
15540.147.64.0/1940.147.64.1 to 40.147.95.25440.147.95.2558,190
15640.147.96.0/1940.147.96.1 to 40.147.127.25440.147.127.2558,190
15740.147.128.0/1940.147.128.1 to 40.147.159.25440.147.159.2558,190
15840.147.160.0/1940.147.160.1 to 40.147.191.25440.147.191.2558,190
15940.147.192.0/1940.147.192.1 to 40.147.223.25440.147.223.2558,190
16040.147.224.0/1940.147.224.1 to 40.147.255.25440.147.255.2558,190
16140.148.0.0/1940.148.0.1 to 40.148.31.25440.148.31.2558,190
16240.148.32.0/1940.148.32.1 to 40.148.63.25440.148.63.2558,190
16340.148.64.0/1940.148.64.1 to 40.148.95.25440.148.95.2558,190
16440.148.96.0/1940.148.96.1 to 40.148.127.25440.148.127.2558,190
16540.148.128.0/1940.148.128.1 to 40.148.159.25440.148.159.2558,190
16640.148.160.0/1940.148.160.1 to 40.148.191.25440.148.191.2558,190
16740.148.192.0/1940.148.192.1 to 40.148.223.25440.148.223.2558,190
16840.148.224.0/1940.148.224.1 to 40.148.255.25440.148.255.2558,190
16940.149.0.0/1940.149.0.1 to 40.149.31.25440.149.31.2558,190
17040.149.32.0/1940.149.32.1 to 40.149.63.25440.149.63.2558,190
17140.149.64.0/1940.149.64.1 to 40.149.95.25440.149.95.2558,190
17240.149.96.0/1940.149.96.1 to 40.149.127.25440.149.127.2558,190
17340.149.128.0/1940.149.128.1 to 40.149.159.25440.149.159.2558,190
17440.149.160.0/1940.149.160.1 to 40.149.191.25440.149.191.2558,190
17540.149.192.0/1940.149.192.1 to 40.149.223.25440.149.223.2558,190
17640.149.224.0/1940.149.224.1 to 40.149.255.25440.149.255.2558,190
17740.150.0.0/1940.150.0.1 to 40.150.31.25440.150.31.2558,190
17840.150.32.0/1940.150.32.1 to 40.150.63.25440.150.63.2558,190
17940.150.64.0/1940.150.64.1 to 40.150.95.25440.150.95.2558,190
18040.150.96.0/1940.150.96.1 to 40.150.127.25440.150.127.2558,190
18140.150.128.0/1940.150.128.1 to 40.150.159.25440.150.159.2558,190
18240.150.160.0/1940.150.160.1 to 40.150.191.25440.150.191.2558,190
18340.150.192.0/1940.150.192.1 to 40.150.223.25440.150.223.2558,190
18440.150.224.0/1940.150.224.1 to 40.150.255.25440.150.255.2558,190
18540.151.0.0/1940.151.0.1 to 40.151.31.25440.151.31.2558,190
18640.151.32.0/1940.151.32.1 to 40.151.63.25440.151.63.2558,190
18740.151.64.0/1940.151.64.1 to 40.151.95.25440.151.95.2558,190
18840.151.96.0/1940.151.96.1 to 40.151.127.25440.151.127.2558,190
18940.151.128.0/1940.151.128.1 to 40.151.159.25440.151.159.2558,190
19040.151.160.0/1940.151.160.1 to 40.151.191.25440.151.191.2558,190
19140.151.192.0/1940.151.192.1 to 40.151.223.25440.151.223.2558,190
19240.151.224.0/1940.151.224.1 to 40.151.255.25440.151.255.2558,190
19340.152.0.0/1940.152.0.1 to 40.152.31.25440.152.31.2558,190
19440.152.32.0/1940.152.32.1 to 40.152.63.25440.152.63.2558,190
19540.152.64.0/1940.152.64.1 to 40.152.95.25440.152.95.2558,190
19640.152.96.0/1940.152.96.1 to 40.152.127.25440.152.127.2558,190
19740.152.128.0/1940.152.128.1 to 40.152.159.25440.152.159.2558,190
19840.152.160.0/1940.152.160.1 to 40.152.191.25440.152.191.2558,190
19940.152.192.0/1940.152.192.1 to 40.152.223.25440.152.223.2558,190
20040.152.224.0/1940.152.224.1 to 40.152.255.25440.152.255.2558,190
20140.153.0.0/1940.153.0.1 to 40.153.31.25440.153.31.2558,190
20240.153.32.0/1940.153.32.1 to 40.153.63.25440.153.63.2558,190
20340.153.64.0/1940.153.64.1 to 40.153.95.25440.153.95.2558,190
20440.153.96.0/1940.153.96.1 to 40.153.127.25440.153.127.2558,190
20540.153.128.0/1940.153.128.1 to 40.153.159.25440.153.159.2558,190
20640.153.160.0/1940.153.160.1 to 40.153.191.25440.153.191.2558,190
20740.153.192.0/1940.153.192.1 to 40.153.223.25440.153.223.2558,190
20840.153.224.0/1940.153.224.1 to 40.153.255.25440.153.255.2558,190
20940.154.0.0/1940.154.0.1 to 40.154.31.25440.154.31.2558,190
21040.154.32.0/1940.154.32.1 to 40.154.63.25440.154.63.2558,190
21140.154.64.0/1940.154.64.1 to 40.154.95.25440.154.95.2558,190
21240.154.96.0/1940.154.96.1 to 40.154.127.25440.154.127.2558,190
21340.154.128.0/1940.154.128.1 to 40.154.159.25440.154.159.2558,190
21440.154.160.0/1940.154.160.1 to 40.154.191.25440.154.191.2558,190
21540.154.192.0/1940.154.192.1 to 40.154.223.25440.154.223.2558,190
21640.154.224.0/1940.154.224.1 to 40.154.255.25440.154.255.2558,190
21740.155.0.0/1940.155.0.1 to 40.155.31.25440.155.31.2558,190
21840.155.32.0/1940.155.32.1 to 40.155.63.25440.155.63.2558,190
21940.155.64.0/1940.155.64.1 to 40.155.95.25440.155.95.2558,190
22040.155.96.0/1940.155.96.1 to 40.155.127.25440.155.127.2558,190
22140.155.128.0/1940.155.128.1 to 40.155.159.25440.155.159.2558,190
22240.155.160.0/1940.155.160.1 to 40.155.191.25440.155.191.2558,190
22340.155.192.0/1940.155.192.1 to 40.155.223.25440.155.223.2558,190
22440.155.224.0/1940.155.224.1 to 40.155.255.25440.155.255.2558,190
22540.156.0.0/1940.156.0.1 to 40.156.31.25440.156.31.2558,190
22640.156.32.0/1940.156.32.1 to 40.156.63.25440.156.63.2558,190
22740.156.64.0/1940.156.64.1 to 40.156.95.25440.156.95.2558,190
22840.156.96.0/1940.156.96.1 to 40.156.127.25440.156.127.2558,190
22940.156.128.0/1940.156.128.1 to 40.156.159.25440.156.159.2558,190
23040.156.160.0/1940.156.160.1 to 40.156.191.25440.156.191.2558,190
23140.156.192.0/1940.156.192.1 to 40.156.223.25440.156.223.2558,190
23240.156.224.0/1940.156.224.1 to 40.156.255.25440.156.255.2558,190
23340.157.0.0/1940.157.0.1 to 40.157.31.25440.157.31.2558,190
23440.157.32.0/1940.157.32.1 to 40.157.63.25440.157.63.2558,190
23540.157.64.0/1940.157.64.1 to 40.157.95.25440.157.95.2558,190
23640.157.96.0/1940.157.96.1 to 40.157.127.25440.157.127.2558,190
23740.157.128.0/1940.157.128.1 to 40.157.159.25440.157.159.2558,190
23840.157.160.0/1940.157.160.1 to 40.157.191.25440.157.191.2558,190
23940.157.192.0/1940.157.192.1 to 40.157.223.25440.157.223.2558,190
24040.157.224.0/1940.157.224.1 to 40.157.255.25440.157.255.2558,190
24140.158.0.0/1940.158.0.1 to 40.158.31.25440.158.31.2558,190
24240.158.32.0/1940.158.32.1 to 40.158.63.25440.158.63.2558,190
24340.158.64.0/1940.158.64.1 to 40.158.95.25440.158.95.2558,190
24440.158.96.0/1940.158.96.1 to 40.158.127.25440.158.127.2558,190
24540.158.128.0/1940.158.128.1 to 40.158.159.25440.158.159.2558,190
24640.158.160.0/1940.158.160.1 to 40.158.191.25440.158.191.2558,190
24740.158.192.0/1940.158.192.1 to 40.158.223.25440.158.223.2558,190
24840.158.224.0/1940.158.224.1 to 40.158.255.25440.158.255.2558,190
24940.159.0.0/1940.159.0.1 to 40.159.31.25440.159.31.2558,190
25040.159.32.0/1940.159.32.1 to 40.159.63.25440.159.63.2558,190
25140.159.64.0/1940.159.64.1 to 40.159.95.25440.159.95.2558,190
25240.159.96.0/1940.159.96.1 to 40.159.127.25440.159.127.2558,190
25340.159.128.0/1940.159.128.1 to 40.159.159.25440.159.159.2558,190
25440.159.160.0/1940.159.160.1 to 40.159.191.25440.159.191.2558,190
25540.159.192.0/1940.159.192.1 to 40.159.223.25440.159.223.2558,190
25640.159.224.0/1940.159.224.1 to 40.159.255.25440.159.255.2558,190

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.