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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.

Network18.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
18.0.0.0
Broadcast address
18.255.255.255
First usable
18.0.0.1
Last usable
18.255.255.254
Usable hosts
16,777,214 (16,777,216 less the network and broadcast addresses)
Subnet mask
255.0.0.0
Wildcard mask
0.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/8
Type
Public public
Old class
A (default /8)
As numbers
Hex 12000000 · Integer 301989888 to 318767103
Reverse DNS zone
18.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00010010..00000000.00000000.0000000018.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network00010010..00000000.00000000.0000000018.0.0.0
Broadcast00010010..11111111.11111111.1111111118.255.255.255
Split into smaller subnets/20
/9 (2)/10 (4)/11 (8)/12 (16)/13 (32)/14 (64)/15 (128)/16 (256)/17 (512)/18 (1,024)/19 (2,048)/20 (4,096)

18.0.0.0/8 makes 4,096 subnets of /20; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
118.0.0.0/2018.0.0.1 to 18.0.15.25418.0.15.2554,094
218.0.16.0/2018.0.16.1 to 18.0.31.25418.0.31.2554,094
318.0.32.0/2018.0.32.1 to 18.0.47.25418.0.47.2554,094
418.0.48.0/2018.0.48.1 to 18.0.63.25418.0.63.2554,094
518.0.64.0/2018.0.64.1 to 18.0.79.25418.0.79.2554,094
618.0.80.0/2018.0.80.1 to 18.0.95.25418.0.95.2554,094
718.0.96.0/2018.0.96.1 to 18.0.111.25418.0.111.2554,094
818.0.112.0/2018.0.112.1 to 18.0.127.25418.0.127.2554,094
918.0.128.0/2018.0.128.1 to 18.0.143.25418.0.143.2554,094
1018.0.144.0/2018.0.144.1 to 18.0.159.25418.0.159.2554,094
1118.0.160.0/2018.0.160.1 to 18.0.175.25418.0.175.2554,094
1218.0.176.0/2018.0.176.1 to 18.0.191.25418.0.191.2554,094
1318.0.192.0/2018.0.192.1 to 18.0.207.25418.0.207.2554,094
1418.0.208.0/2018.0.208.1 to 18.0.223.25418.0.223.2554,094
1518.0.224.0/2018.0.224.1 to 18.0.239.25418.0.239.2554,094
1618.0.240.0/2018.0.240.1 to 18.0.255.25418.0.255.2554,094
1718.1.0.0/2018.1.0.1 to 18.1.15.25418.1.15.2554,094
1818.1.16.0/2018.1.16.1 to 18.1.31.25418.1.31.2554,094
1918.1.32.0/2018.1.32.1 to 18.1.47.25418.1.47.2554,094
2018.1.48.0/2018.1.48.1 to 18.1.63.25418.1.63.2554,094
2118.1.64.0/2018.1.64.1 to 18.1.79.25418.1.79.2554,094
2218.1.80.0/2018.1.80.1 to 18.1.95.25418.1.95.2554,094
2318.1.96.0/2018.1.96.1 to 18.1.111.25418.1.111.2554,094
2418.1.112.0/2018.1.112.1 to 18.1.127.25418.1.127.2554,094
2518.1.128.0/2018.1.128.1 to 18.1.143.25418.1.143.2554,094
2618.1.144.0/2018.1.144.1 to 18.1.159.25418.1.159.2554,094
2718.1.160.0/2018.1.160.1 to 18.1.175.25418.1.175.2554,094
2818.1.176.0/2018.1.176.1 to 18.1.191.25418.1.191.2554,094
2918.1.192.0/2018.1.192.1 to 18.1.207.25418.1.207.2554,094
3018.1.208.0/2018.1.208.1 to 18.1.223.25418.1.223.2554,094
3118.1.224.0/2018.1.224.1 to 18.1.239.25418.1.239.2554,094
3218.1.240.0/2018.1.240.1 to 18.1.255.25418.1.255.2554,094
3318.2.0.0/2018.2.0.1 to 18.2.15.25418.2.15.2554,094
3418.2.16.0/2018.2.16.1 to 18.2.31.25418.2.31.2554,094
3518.2.32.0/2018.2.32.1 to 18.2.47.25418.2.47.2554,094
3618.2.48.0/2018.2.48.1 to 18.2.63.25418.2.63.2554,094
3718.2.64.0/2018.2.64.1 to 18.2.79.25418.2.79.2554,094
3818.2.80.0/2018.2.80.1 to 18.2.95.25418.2.95.2554,094
3918.2.96.0/2018.2.96.1 to 18.2.111.25418.2.111.2554,094
4018.2.112.0/2018.2.112.1 to 18.2.127.25418.2.127.2554,094
4118.2.128.0/2018.2.128.1 to 18.2.143.25418.2.143.2554,094
4218.2.144.0/2018.2.144.1 to 18.2.159.25418.2.159.2554,094
4318.2.160.0/2018.2.160.1 to 18.2.175.25418.2.175.2554,094
4418.2.176.0/2018.2.176.1 to 18.2.191.25418.2.191.2554,094
4518.2.192.0/2018.2.192.1 to 18.2.207.25418.2.207.2554,094
4618.2.208.0/2018.2.208.1 to 18.2.223.25418.2.223.2554,094
4718.2.224.0/2018.2.224.1 to 18.2.239.25418.2.239.2554,094
4818.2.240.0/2018.2.240.1 to 18.2.255.25418.2.255.2554,094
4918.3.0.0/2018.3.0.1 to 18.3.15.25418.3.15.2554,094
5018.3.16.0/2018.3.16.1 to 18.3.31.25418.3.31.2554,094
5118.3.32.0/2018.3.32.1 to 18.3.47.25418.3.47.2554,094
5218.3.48.0/2018.3.48.1 to 18.3.63.25418.3.63.2554,094
5318.3.64.0/2018.3.64.1 to 18.3.79.25418.3.79.2554,094
5418.3.80.0/2018.3.80.1 to 18.3.95.25418.3.95.2554,094
5518.3.96.0/2018.3.96.1 to 18.3.111.25418.3.111.2554,094
5618.3.112.0/2018.3.112.1 to 18.3.127.25418.3.127.2554,094
5718.3.128.0/2018.3.128.1 to 18.3.143.25418.3.143.2554,094
5818.3.144.0/2018.3.144.1 to 18.3.159.25418.3.159.2554,094
5918.3.160.0/2018.3.160.1 to 18.3.175.25418.3.175.2554,094
6018.3.176.0/2018.3.176.1 to 18.3.191.25418.3.191.2554,094
6118.3.192.0/2018.3.192.1 to 18.3.207.25418.3.207.2554,094
6218.3.208.0/2018.3.208.1 to 18.3.223.25418.3.223.2554,094
6318.3.224.0/2018.3.224.1 to 18.3.239.25418.3.239.2554,094
6418.3.240.0/2018.3.240.1 to 18.3.255.25418.3.255.2554,094
6518.4.0.0/2018.4.0.1 to 18.4.15.25418.4.15.2554,094
6618.4.16.0/2018.4.16.1 to 18.4.31.25418.4.31.2554,094
6718.4.32.0/2018.4.32.1 to 18.4.47.25418.4.47.2554,094
6818.4.48.0/2018.4.48.1 to 18.4.63.25418.4.63.2554,094
6918.4.64.0/2018.4.64.1 to 18.4.79.25418.4.79.2554,094
7018.4.80.0/2018.4.80.1 to 18.4.95.25418.4.95.2554,094
7118.4.96.0/2018.4.96.1 to 18.4.111.25418.4.111.2554,094
7218.4.112.0/2018.4.112.1 to 18.4.127.25418.4.127.2554,094
7318.4.128.0/2018.4.128.1 to 18.4.143.25418.4.143.2554,094
7418.4.144.0/2018.4.144.1 to 18.4.159.25418.4.159.2554,094
7518.4.160.0/2018.4.160.1 to 18.4.175.25418.4.175.2554,094
7618.4.176.0/2018.4.176.1 to 18.4.191.25418.4.191.2554,094
7718.4.192.0/2018.4.192.1 to 18.4.207.25418.4.207.2554,094
7818.4.208.0/2018.4.208.1 to 18.4.223.25418.4.223.2554,094
7918.4.224.0/2018.4.224.1 to 18.4.239.25418.4.239.2554,094
8018.4.240.0/2018.4.240.1 to 18.4.255.25418.4.255.2554,094
8118.5.0.0/2018.5.0.1 to 18.5.15.25418.5.15.2554,094
8218.5.16.0/2018.5.16.1 to 18.5.31.25418.5.31.2554,094
8318.5.32.0/2018.5.32.1 to 18.5.47.25418.5.47.2554,094
8418.5.48.0/2018.5.48.1 to 18.5.63.25418.5.63.2554,094
8518.5.64.0/2018.5.64.1 to 18.5.79.25418.5.79.2554,094
8618.5.80.0/2018.5.80.1 to 18.5.95.25418.5.95.2554,094
8718.5.96.0/2018.5.96.1 to 18.5.111.25418.5.111.2554,094
8818.5.112.0/2018.5.112.1 to 18.5.127.25418.5.127.2554,094
8918.5.128.0/2018.5.128.1 to 18.5.143.25418.5.143.2554,094
9018.5.144.0/2018.5.144.1 to 18.5.159.25418.5.159.2554,094
9118.5.160.0/2018.5.160.1 to 18.5.175.25418.5.175.2554,094
9218.5.176.0/2018.5.176.1 to 18.5.191.25418.5.191.2554,094
9318.5.192.0/2018.5.192.1 to 18.5.207.25418.5.207.2554,094
9418.5.208.0/2018.5.208.1 to 18.5.223.25418.5.223.2554,094
9518.5.224.0/2018.5.224.1 to 18.5.239.25418.5.239.2554,094
9618.5.240.0/2018.5.240.1 to 18.5.255.25418.5.255.2554,094
9718.6.0.0/2018.6.0.1 to 18.6.15.25418.6.15.2554,094
9818.6.16.0/2018.6.16.1 to 18.6.31.25418.6.31.2554,094
9918.6.32.0/2018.6.32.1 to 18.6.47.25418.6.47.2554,094
10018.6.48.0/2018.6.48.1 to 18.6.63.25418.6.63.2554,094
10118.6.64.0/2018.6.64.1 to 18.6.79.25418.6.79.2554,094
10218.6.80.0/2018.6.80.1 to 18.6.95.25418.6.95.2554,094
10318.6.96.0/2018.6.96.1 to 18.6.111.25418.6.111.2554,094
10418.6.112.0/2018.6.112.1 to 18.6.127.25418.6.127.2554,094
10518.6.128.0/2018.6.128.1 to 18.6.143.25418.6.143.2554,094
10618.6.144.0/2018.6.144.1 to 18.6.159.25418.6.159.2554,094
10718.6.160.0/2018.6.160.1 to 18.6.175.25418.6.175.2554,094
10818.6.176.0/2018.6.176.1 to 18.6.191.25418.6.191.2554,094
10918.6.192.0/2018.6.192.1 to 18.6.207.25418.6.207.2554,094
11018.6.208.0/2018.6.208.1 to 18.6.223.25418.6.223.2554,094
11118.6.224.0/2018.6.224.1 to 18.6.239.25418.6.239.2554,094
11218.6.240.0/2018.6.240.1 to 18.6.255.25418.6.255.2554,094
11318.7.0.0/2018.7.0.1 to 18.7.15.25418.7.15.2554,094
11418.7.16.0/2018.7.16.1 to 18.7.31.25418.7.31.2554,094
11518.7.32.0/2018.7.32.1 to 18.7.47.25418.7.47.2554,094
11618.7.48.0/2018.7.48.1 to 18.7.63.25418.7.63.2554,094
11718.7.64.0/2018.7.64.1 to 18.7.79.25418.7.79.2554,094
11818.7.80.0/2018.7.80.1 to 18.7.95.25418.7.95.2554,094
11918.7.96.0/2018.7.96.1 to 18.7.111.25418.7.111.2554,094
12018.7.112.0/2018.7.112.1 to 18.7.127.25418.7.127.2554,094
12118.7.128.0/2018.7.128.1 to 18.7.143.25418.7.143.2554,094
12218.7.144.0/2018.7.144.1 to 18.7.159.25418.7.159.2554,094
12318.7.160.0/2018.7.160.1 to 18.7.175.25418.7.175.2554,094
12418.7.176.0/2018.7.176.1 to 18.7.191.25418.7.191.2554,094
12518.7.192.0/2018.7.192.1 to 18.7.207.25418.7.207.2554,094
12618.7.208.0/2018.7.208.1 to 18.7.223.25418.7.223.2554,094
12718.7.224.0/2018.7.224.1 to 18.7.239.25418.7.239.2554,094
12818.7.240.0/2018.7.240.1 to 18.7.255.25418.7.255.2554,094
12918.8.0.0/2018.8.0.1 to 18.8.15.25418.8.15.2554,094
13018.8.16.0/2018.8.16.1 to 18.8.31.25418.8.31.2554,094
13118.8.32.0/2018.8.32.1 to 18.8.47.25418.8.47.2554,094
13218.8.48.0/2018.8.48.1 to 18.8.63.25418.8.63.2554,094
13318.8.64.0/2018.8.64.1 to 18.8.79.25418.8.79.2554,094
13418.8.80.0/2018.8.80.1 to 18.8.95.25418.8.95.2554,094
13518.8.96.0/2018.8.96.1 to 18.8.111.25418.8.111.2554,094
13618.8.112.0/2018.8.112.1 to 18.8.127.25418.8.127.2554,094
13718.8.128.0/2018.8.128.1 to 18.8.143.25418.8.143.2554,094
13818.8.144.0/2018.8.144.1 to 18.8.159.25418.8.159.2554,094
13918.8.160.0/2018.8.160.1 to 18.8.175.25418.8.175.2554,094
14018.8.176.0/2018.8.176.1 to 18.8.191.25418.8.191.2554,094
14118.8.192.0/2018.8.192.1 to 18.8.207.25418.8.207.2554,094
14218.8.208.0/2018.8.208.1 to 18.8.223.25418.8.223.2554,094
14318.8.224.0/2018.8.224.1 to 18.8.239.25418.8.239.2554,094
14418.8.240.0/2018.8.240.1 to 18.8.255.25418.8.255.2554,094
14518.9.0.0/2018.9.0.1 to 18.9.15.25418.9.15.2554,094
14618.9.16.0/2018.9.16.1 to 18.9.31.25418.9.31.2554,094
14718.9.32.0/2018.9.32.1 to 18.9.47.25418.9.47.2554,094
14818.9.48.0/2018.9.48.1 to 18.9.63.25418.9.63.2554,094
14918.9.64.0/2018.9.64.1 to 18.9.79.25418.9.79.2554,094
15018.9.80.0/2018.9.80.1 to 18.9.95.25418.9.95.2554,094
15118.9.96.0/2018.9.96.1 to 18.9.111.25418.9.111.2554,094
15218.9.112.0/2018.9.112.1 to 18.9.127.25418.9.127.2554,094
15318.9.128.0/2018.9.128.1 to 18.9.143.25418.9.143.2554,094
15418.9.144.0/2018.9.144.1 to 18.9.159.25418.9.159.2554,094
15518.9.160.0/2018.9.160.1 to 18.9.175.25418.9.175.2554,094
15618.9.176.0/2018.9.176.1 to 18.9.191.25418.9.191.2554,094
15718.9.192.0/2018.9.192.1 to 18.9.207.25418.9.207.2554,094
15818.9.208.0/2018.9.208.1 to 18.9.223.25418.9.223.2554,094
15918.9.224.0/2018.9.224.1 to 18.9.239.25418.9.239.2554,094
16018.9.240.0/2018.9.240.1 to 18.9.255.25418.9.255.2554,094
16118.10.0.0/2018.10.0.1 to 18.10.15.25418.10.15.2554,094
16218.10.16.0/2018.10.16.1 to 18.10.31.25418.10.31.2554,094
16318.10.32.0/2018.10.32.1 to 18.10.47.25418.10.47.2554,094
16418.10.48.0/2018.10.48.1 to 18.10.63.25418.10.63.2554,094
16518.10.64.0/2018.10.64.1 to 18.10.79.25418.10.79.2554,094
16618.10.80.0/2018.10.80.1 to 18.10.95.25418.10.95.2554,094
16718.10.96.0/2018.10.96.1 to 18.10.111.25418.10.111.2554,094
16818.10.112.0/2018.10.112.1 to 18.10.127.25418.10.127.2554,094
16918.10.128.0/2018.10.128.1 to 18.10.143.25418.10.143.2554,094
17018.10.144.0/2018.10.144.1 to 18.10.159.25418.10.159.2554,094
17118.10.160.0/2018.10.160.1 to 18.10.175.25418.10.175.2554,094
17218.10.176.0/2018.10.176.1 to 18.10.191.25418.10.191.2554,094
17318.10.192.0/2018.10.192.1 to 18.10.207.25418.10.207.2554,094
17418.10.208.0/2018.10.208.1 to 18.10.223.25418.10.223.2554,094
17518.10.224.0/2018.10.224.1 to 18.10.239.25418.10.239.2554,094
17618.10.240.0/2018.10.240.1 to 18.10.255.25418.10.255.2554,094
17718.11.0.0/2018.11.0.1 to 18.11.15.25418.11.15.2554,094
17818.11.16.0/2018.11.16.1 to 18.11.31.25418.11.31.2554,094
17918.11.32.0/2018.11.32.1 to 18.11.47.25418.11.47.2554,094
18018.11.48.0/2018.11.48.1 to 18.11.63.25418.11.63.2554,094
18118.11.64.0/2018.11.64.1 to 18.11.79.25418.11.79.2554,094
18218.11.80.0/2018.11.80.1 to 18.11.95.25418.11.95.2554,094
18318.11.96.0/2018.11.96.1 to 18.11.111.25418.11.111.2554,094
18418.11.112.0/2018.11.112.1 to 18.11.127.25418.11.127.2554,094
18518.11.128.0/2018.11.128.1 to 18.11.143.25418.11.143.2554,094
18618.11.144.0/2018.11.144.1 to 18.11.159.25418.11.159.2554,094
18718.11.160.0/2018.11.160.1 to 18.11.175.25418.11.175.2554,094
18818.11.176.0/2018.11.176.1 to 18.11.191.25418.11.191.2554,094
18918.11.192.0/2018.11.192.1 to 18.11.207.25418.11.207.2554,094
19018.11.208.0/2018.11.208.1 to 18.11.223.25418.11.223.2554,094
19118.11.224.0/2018.11.224.1 to 18.11.239.25418.11.239.2554,094
19218.11.240.0/2018.11.240.1 to 18.11.255.25418.11.255.2554,094
19318.12.0.0/2018.12.0.1 to 18.12.15.25418.12.15.2554,094
19418.12.16.0/2018.12.16.1 to 18.12.31.25418.12.31.2554,094
19518.12.32.0/2018.12.32.1 to 18.12.47.25418.12.47.2554,094
19618.12.48.0/2018.12.48.1 to 18.12.63.25418.12.63.2554,094
19718.12.64.0/2018.12.64.1 to 18.12.79.25418.12.79.2554,094
19818.12.80.0/2018.12.80.1 to 18.12.95.25418.12.95.2554,094
19918.12.96.0/2018.12.96.1 to 18.12.111.25418.12.111.2554,094
20018.12.112.0/2018.12.112.1 to 18.12.127.25418.12.127.2554,094
20118.12.128.0/2018.12.128.1 to 18.12.143.25418.12.143.2554,094
20218.12.144.0/2018.12.144.1 to 18.12.159.25418.12.159.2554,094
20318.12.160.0/2018.12.160.1 to 18.12.175.25418.12.175.2554,094
20418.12.176.0/2018.12.176.1 to 18.12.191.25418.12.191.2554,094
20518.12.192.0/2018.12.192.1 to 18.12.207.25418.12.207.2554,094
20618.12.208.0/2018.12.208.1 to 18.12.223.25418.12.223.2554,094
20718.12.224.0/2018.12.224.1 to 18.12.239.25418.12.239.2554,094
20818.12.240.0/2018.12.240.1 to 18.12.255.25418.12.255.2554,094
20918.13.0.0/2018.13.0.1 to 18.13.15.25418.13.15.2554,094
21018.13.16.0/2018.13.16.1 to 18.13.31.25418.13.31.2554,094
21118.13.32.0/2018.13.32.1 to 18.13.47.25418.13.47.2554,094
21218.13.48.0/2018.13.48.1 to 18.13.63.25418.13.63.2554,094
21318.13.64.0/2018.13.64.1 to 18.13.79.25418.13.79.2554,094
21418.13.80.0/2018.13.80.1 to 18.13.95.25418.13.95.2554,094
21518.13.96.0/2018.13.96.1 to 18.13.111.25418.13.111.2554,094
21618.13.112.0/2018.13.112.1 to 18.13.127.25418.13.127.2554,094
21718.13.128.0/2018.13.128.1 to 18.13.143.25418.13.143.2554,094
21818.13.144.0/2018.13.144.1 to 18.13.159.25418.13.159.2554,094
21918.13.160.0/2018.13.160.1 to 18.13.175.25418.13.175.2554,094
22018.13.176.0/2018.13.176.1 to 18.13.191.25418.13.191.2554,094
22118.13.192.0/2018.13.192.1 to 18.13.207.25418.13.207.2554,094
22218.13.208.0/2018.13.208.1 to 18.13.223.25418.13.223.2554,094
22318.13.224.0/2018.13.224.1 to 18.13.239.25418.13.239.2554,094
22418.13.240.0/2018.13.240.1 to 18.13.255.25418.13.255.2554,094
22518.14.0.0/2018.14.0.1 to 18.14.15.25418.14.15.2554,094
22618.14.16.0/2018.14.16.1 to 18.14.31.25418.14.31.2554,094
22718.14.32.0/2018.14.32.1 to 18.14.47.25418.14.47.2554,094
22818.14.48.0/2018.14.48.1 to 18.14.63.25418.14.63.2554,094
22918.14.64.0/2018.14.64.1 to 18.14.79.25418.14.79.2554,094
23018.14.80.0/2018.14.80.1 to 18.14.95.25418.14.95.2554,094
23118.14.96.0/2018.14.96.1 to 18.14.111.25418.14.111.2554,094
23218.14.112.0/2018.14.112.1 to 18.14.127.25418.14.127.2554,094
23318.14.128.0/2018.14.128.1 to 18.14.143.25418.14.143.2554,094
23418.14.144.0/2018.14.144.1 to 18.14.159.25418.14.159.2554,094
23518.14.160.0/2018.14.160.1 to 18.14.175.25418.14.175.2554,094
23618.14.176.0/2018.14.176.1 to 18.14.191.25418.14.191.2554,094
23718.14.192.0/2018.14.192.1 to 18.14.207.25418.14.207.2554,094
23818.14.208.0/2018.14.208.1 to 18.14.223.25418.14.223.2554,094
23918.14.224.0/2018.14.224.1 to 18.14.239.25418.14.239.2554,094
24018.14.240.0/2018.14.240.1 to 18.14.255.25418.14.255.2554,094
24118.15.0.0/2018.15.0.1 to 18.15.15.25418.15.15.2554,094
24218.15.16.0/2018.15.16.1 to 18.15.31.25418.15.31.2554,094
24318.15.32.0/2018.15.32.1 to 18.15.47.25418.15.47.2554,094
24418.15.48.0/2018.15.48.1 to 18.15.63.25418.15.63.2554,094
24518.15.64.0/2018.15.64.1 to 18.15.79.25418.15.79.2554,094
24618.15.80.0/2018.15.80.1 to 18.15.95.25418.15.95.2554,094
24718.15.96.0/2018.15.96.1 to 18.15.111.25418.15.111.2554,094
24818.15.112.0/2018.15.112.1 to 18.15.127.25418.15.127.2554,094
24918.15.128.0/2018.15.128.1 to 18.15.143.25418.15.143.2554,094
25018.15.144.0/2018.15.144.1 to 18.15.159.25418.15.159.2554,094
25118.15.160.0/2018.15.160.1 to 18.15.175.25418.15.175.2554,094
25218.15.176.0/2018.15.176.1 to 18.15.191.25418.15.191.2554,094
25318.15.192.0/2018.15.192.1 to 18.15.207.25418.15.207.2554,094
25418.15.208.0/2018.15.208.1 to 18.15.223.25418.15.223.2554,094
25518.15.224.0/2018.15.224.1 to 18.15.239.25418.15.239.2554,094
25618.15.240.0/2018.15.240.1 to 18.15.255.25418.15.255.2554,094

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.