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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/19
/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 2,048 subnets of /19; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
118.0.0.0/1918.0.0.1 to 18.0.31.25418.0.31.2558,190
218.0.32.0/1918.0.32.1 to 18.0.63.25418.0.63.2558,190
318.0.64.0/1918.0.64.1 to 18.0.95.25418.0.95.2558,190
418.0.96.0/1918.0.96.1 to 18.0.127.25418.0.127.2558,190
518.0.128.0/1918.0.128.1 to 18.0.159.25418.0.159.2558,190
618.0.160.0/1918.0.160.1 to 18.0.191.25418.0.191.2558,190
718.0.192.0/1918.0.192.1 to 18.0.223.25418.0.223.2558,190
818.0.224.0/1918.0.224.1 to 18.0.255.25418.0.255.2558,190
918.1.0.0/1918.1.0.1 to 18.1.31.25418.1.31.2558,190
1018.1.32.0/1918.1.32.1 to 18.1.63.25418.1.63.2558,190
1118.1.64.0/1918.1.64.1 to 18.1.95.25418.1.95.2558,190
1218.1.96.0/1918.1.96.1 to 18.1.127.25418.1.127.2558,190
1318.1.128.0/1918.1.128.1 to 18.1.159.25418.1.159.2558,190
1418.1.160.0/1918.1.160.1 to 18.1.191.25418.1.191.2558,190
1518.1.192.0/1918.1.192.1 to 18.1.223.25418.1.223.2558,190
1618.1.224.0/1918.1.224.1 to 18.1.255.25418.1.255.2558,190
1718.2.0.0/1918.2.0.1 to 18.2.31.25418.2.31.2558,190
1818.2.32.0/1918.2.32.1 to 18.2.63.25418.2.63.2558,190
1918.2.64.0/1918.2.64.1 to 18.2.95.25418.2.95.2558,190
2018.2.96.0/1918.2.96.1 to 18.2.127.25418.2.127.2558,190
2118.2.128.0/1918.2.128.1 to 18.2.159.25418.2.159.2558,190
2218.2.160.0/1918.2.160.1 to 18.2.191.25418.2.191.2558,190
2318.2.192.0/1918.2.192.1 to 18.2.223.25418.2.223.2558,190
2418.2.224.0/1918.2.224.1 to 18.2.255.25418.2.255.2558,190
2518.3.0.0/1918.3.0.1 to 18.3.31.25418.3.31.2558,190
2618.3.32.0/1918.3.32.1 to 18.3.63.25418.3.63.2558,190
2718.3.64.0/1918.3.64.1 to 18.3.95.25418.3.95.2558,190
2818.3.96.0/1918.3.96.1 to 18.3.127.25418.3.127.2558,190
2918.3.128.0/1918.3.128.1 to 18.3.159.25418.3.159.2558,190
3018.3.160.0/1918.3.160.1 to 18.3.191.25418.3.191.2558,190
3118.3.192.0/1918.3.192.1 to 18.3.223.25418.3.223.2558,190
3218.3.224.0/1918.3.224.1 to 18.3.255.25418.3.255.2558,190
3318.4.0.0/1918.4.0.1 to 18.4.31.25418.4.31.2558,190
3418.4.32.0/1918.4.32.1 to 18.4.63.25418.4.63.2558,190
3518.4.64.0/1918.4.64.1 to 18.4.95.25418.4.95.2558,190
3618.4.96.0/1918.4.96.1 to 18.4.127.25418.4.127.2558,190
3718.4.128.0/1918.4.128.1 to 18.4.159.25418.4.159.2558,190
3818.4.160.0/1918.4.160.1 to 18.4.191.25418.4.191.2558,190
3918.4.192.0/1918.4.192.1 to 18.4.223.25418.4.223.2558,190
4018.4.224.0/1918.4.224.1 to 18.4.255.25418.4.255.2558,190
4118.5.0.0/1918.5.0.1 to 18.5.31.25418.5.31.2558,190
4218.5.32.0/1918.5.32.1 to 18.5.63.25418.5.63.2558,190
4318.5.64.0/1918.5.64.1 to 18.5.95.25418.5.95.2558,190
4418.5.96.0/1918.5.96.1 to 18.5.127.25418.5.127.2558,190
4518.5.128.0/1918.5.128.1 to 18.5.159.25418.5.159.2558,190
4618.5.160.0/1918.5.160.1 to 18.5.191.25418.5.191.2558,190
4718.5.192.0/1918.5.192.1 to 18.5.223.25418.5.223.2558,190
4818.5.224.0/1918.5.224.1 to 18.5.255.25418.5.255.2558,190
4918.6.0.0/1918.6.0.1 to 18.6.31.25418.6.31.2558,190
5018.6.32.0/1918.6.32.1 to 18.6.63.25418.6.63.2558,190
5118.6.64.0/1918.6.64.1 to 18.6.95.25418.6.95.2558,190
5218.6.96.0/1918.6.96.1 to 18.6.127.25418.6.127.2558,190
5318.6.128.0/1918.6.128.1 to 18.6.159.25418.6.159.2558,190
5418.6.160.0/1918.6.160.1 to 18.6.191.25418.6.191.2558,190
5518.6.192.0/1918.6.192.1 to 18.6.223.25418.6.223.2558,190
5618.6.224.0/1918.6.224.1 to 18.6.255.25418.6.255.2558,190
5718.7.0.0/1918.7.0.1 to 18.7.31.25418.7.31.2558,190
5818.7.32.0/1918.7.32.1 to 18.7.63.25418.7.63.2558,190
5918.7.64.0/1918.7.64.1 to 18.7.95.25418.7.95.2558,190
6018.7.96.0/1918.7.96.1 to 18.7.127.25418.7.127.2558,190
6118.7.128.0/1918.7.128.1 to 18.7.159.25418.7.159.2558,190
6218.7.160.0/1918.7.160.1 to 18.7.191.25418.7.191.2558,190
6318.7.192.0/1918.7.192.1 to 18.7.223.25418.7.223.2558,190
6418.7.224.0/1918.7.224.1 to 18.7.255.25418.7.255.2558,190
6518.8.0.0/1918.8.0.1 to 18.8.31.25418.8.31.2558,190
6618.8.32.0/1918.8.32.1 to 18.8.63.25418.8.63.2558,190
6718.8.64.0/1918.8.64.1 to 18.8.95.25418.8.95.2558,190
6818.8.96.0/1918.8.96.1 to 18.8.127.25418.8.127.2558,190
6918.8.128.0/1918.8.128.1 to 18.8.159.25418.8.159.2558,190
7018.8.160.0/1918.8.160.1 to 18.8.191.25418.8.191.2558,190
7118.8.192.0/1918.8.192.1 to 18.8.223.25418.8.223.2558,190
7218.8.224.0/1918.8.224.1 to 18.8.255.25418.8.255.2558,190
7318.9.0.0/1918.9.0.1 to 18.9.31.25418.9.31.2558,190
7418.9.32.0/1918.9.32.1 to 18.9.63.25418.9.63.2558,190
7518.9.64.0/1918.9.64.1 to 18.9.95.25418.9.95.2558,190
7618.9.96.0/1918.9.96.1 to 18.9.127.25418.9.127.2558,190
7718.9.128.0/1918.9.128.1 to 18.9.159.25418.9.159.2558,190
7818.9.160.0/1918.9.160.1 to 18.9.191.25418.9.191.2558,190
7918.9.192.0/1918.9.192.1 to 18.9.223.25418.9.223.2558,190
8018.9.224.0/1918.9.224.1 to 18.9.255.25418.9.255.2558,190
8118.10.0.0/1918.10.0.1 to 18.10.31.25418.10.31.2558,190
8218.10.32.0/1918.10.32.1 to 18.10.63.25418.10.63.2558,190
8318.10.64.0/1918.10.64.1 to 18.10.95.25418.10.95.2558,190
8418.10.96.0/1918.10.96.1 to 18.10.127.25418.10.127.2558,190
8518.10.128.0/1918.10.128.1 to 18.10.159.25418.10.159.2558,190
8618.10.160.0/1918.10.160.1 to 18.10.191.25418.10.191.2558,190
8718.10.192.0/1918.10.192.1 to 18.10.223.25418.10.223.2558,190
8818.10.224.0/1918.10.224.1 to 18.10.255.25418.10.255.2558,190
8918.11.0.0/1918.11.0.1 to 18.11.31.25418.11.31.2558,190
9018.11.32.0/1918.11.32.1 to 18.11.63.25418.11.63.2558,190
9118.11.64.0/1918.11.64.1 to 18.11.95.25418.11.95.2558,190
9218.11.96.0/1918.11.96.1 to 18.11.127.25418.11.127.2558,190
9318.11.128.0/1918.11.128.1 to 18.11.159.25418.11.159.2558,190
9418.11.160.0/1918.11.160.1 to 18.11.191.25418.11.191.2558,190
9518.11.192.0/1918.11.192.1 to 18.11.223.25418.11.223.2558,190
9618.11.224.0/1918.11.224.1 to 18.11.255.25418.11.255.2558,190
9718.12.0.0/1918.12.0.1 to 18.12.31.25418.12.31.2558,190
9818.12.32.0/1918.12.32.1 to 18.12.63.25418.12.63.2558,190
9918.12.64.0/1918.12.64.1 to 18.12.95.25418.12.95.2558,190
10018.12.96.0/1918.12.96.1 to 18.12.127.25418.12.127.2558,190
10118.12.128.0/1918.12.128.1 to 18.12.159.25418.12.159.2558,190
10218.12.160.0/1918.12.160.1 to 18.12.191.25418.12.191.2558,190
10318.12.192.0/1918.12.192.1 to 18.12.223.25418.12.223.2558,190
10418.12.224.0/1918.12.224.1 to 18.12.255.25418.12.255.2558,190
10518.13.0.0/1918.13.0.1 to 18.13.31.25418.13.31.2558,190
10618.13.32.0/1918.13.32.1 to 18.13.63.25418.13.63.2558,190
10718.13.64.0/1918.13.64.1 to 18.13.95.25418.13.95.2558,190
10818.13.96.0/1918.13.96.1 to 18.13.127.25418.13.127.2558,190
10918.13.128.0/1918.13.128.1 to 18.13.159.25418.13.159.2558,190
11018.13.160.0/1918.13.160.1 to 18.13.191.25418.13.191.2558,190
11118.13.192.0/1918.13.192.1 to 18.13.223.25418.13.223.2558,190
11218.13.224.0/1918.13.224.1 to 18.13.255.25418.13.255.2558,190
11318.14.0.0/1918.14.0.1 to 18.14.31.25418.14.31.2558,190
11418.14.32.0/1918.14.32.1 to 18.14.63.25418.14.63.2558,190
11518.14.64.0/1918.14.64.1 to 18.14.95.25418.14.95.2558,190
11618.14.96.0/1918.14.96.1 to 18.14.127.25418.14.127.2558,190
11718.14.128.0/1918.14.128.1 to 18.14.159.25418.14.159.2558,190
11818.14.160.0/1918.14.160.1 to 18.14.191.25418.14.191.2558,190
11918.14.192.0/1918.14.192.1 to 18.14.223.25418.14.223.2558,190
12018.14.224.0/1918.14.224.1 to 18.14.255.25418.14.255.2558,190
12118.15.0.0/1918.15.0.1 to 18.15.31.25418.15.31.2558,190
12218.15.32.0/1918.15.32.1 to 18.15.63.25418.15.63.2558,190
12318.15.64.0/1918.15.64.1 to 18.15.95.25418.15.95.2558,190
12418.15.96.0/1918.15.96.1 to 18.15.127.25418.15.127.2558,190
12518.15.128.0/1918.15.128.1 to 18.15.159.25418.15.159.2558,190
12618.15.160.0/1918.15.160.1 to 18.15.191.25418.15.191.2558,190
12718.15.192.0/1918.15.192.1 to 18.15.223.25418.15.223.2558,190
12818.15.224.0/1918.15.224.1 to 18.15.255.25418.15.255.2558,190
12918.16.0.0/1918.16.0.1 to 18.16.31.25418.16.31.2558,190
13018.16.32.0/1918.16.32.1 to 18.16.63.25418.16.63.2558,190
13118.16.64.0/1918.16.64.1 to 18.16.95.25418.16.95.2558,190
13218.16.96.0/1918.16.96.1 to 18.16.127.25418.16.127.2558,190
13318.16.128.0/1918.16.128.1 to 18.16.159.25418.16.159.2558,190
13418.16.160.0/1918.16.160.1 to 18.16.191.25418.16.191.2558,190
13518.16.192.0/1918.16.192.1 to 18.16.223.25418.16.223.2558,190
13618.16.224.0/1918.16.224.1 to 18.16.255.25418.16.255.2558,190
13718.17.0.0/1918.17.0.1 to 18.17.31.25418.17.31.2558,190
13818.17.32.0/1918.17.32.1 to 18.17.63.25418.17.63.2558,190
13918.17.64.0/1918.17.64.1 to 18.17.95.25418.17.95.2558,190
14018.17.96.0/1918.17.96.1 to 18.17.127.25418.17.127.2558,190
14118.17.128.0/1918.17.128.1 to 18.17.159.25418.17.159.2558,190
14218.17.160.0/1918.17.160.1 to 18.17.191.25418.17.191.2558,190
14318.17.192.0/1918.17.192.1 to 18.17.223.25418.17.223.2558,190
14418.17.224.0/1918.17.224.1 to 18.17.255.25418.17.255.2558,190
14518.18.0.0/1918.18.0.1 to 18.18.31.25418.18.31.2558,190
14618.18.32.0/1918.18.32.1 to 18.18.63.25418.18.63.2558,190
14718.18.64.0/1918.18.64.1 to 18.18.95.25418.18.95.2558,190
14818.18.96.0/1918.18.96.1 to 18.18.127.25418.18.127.2558,190
14918.18.128.0/1918.18.128.1 to 18.18.159.25418.18.159.2558,190
15018.18.160.0/1918.18.160.1 to 18.18.191.25418.18.191.2558,190
15118.18.192.0/1918.18.192.1 to 18.18.223.25418.18.223.2558,190
15218.18.224.0/1918.18.224.1 to 18.18.255.25418.18.255.2558,190
15318.19.0.0/1918.19.0.1 to 18.19.31.25418.19.31.2558,190
15418.19.32.0/1918.19.32.1 to 18.19.63.25418.19.63.2558,190
15518.19.64.0/1918.19.64.1 to 18.19.95.25418.19.95.2558,190
15618.19.96.0/1918.19.96.1 to 18.19.127.25418.19.127.2558,190
15718.19.128.0/1918.19.128.1 to 18.19.159.25418.19.159.2558,190
15818.19.160.0/1918.19.160.1 to 18.19.191.25418.19.191.2558,190
15918.19.192.0/1918.19.192.1 to 18.19.223.25418.19.223.2558,190
16018.19.224.0/1918.19.224.1 to 18.19.255.25418.19.255.2558,190
16118.20.0.0/1918.20.0.1 to 18.20.31.25418.20.31.2558,190
16218.20.32.0/1918.20.32.1 to 18.20.63.25418.20.63.2558,190
16318.20.64.0/1918.20.64.1 to 18.20.95.25418.20.95.2558,190
16418.20.96.0/1918.20.96.1 to 18.20.127.25418.20.127.2558,190
16518.20.128.0/1918.20.128.1 to 18.20.159.25418.20.159.2558,190
16618.20.160.0/1918.20.160.1 to 18.20.191.25418.20.191.2558,190
16718.20.192.0/1918.20.192.1 to 18.20.223.25418.20.223.2558,190
16818.20.224.0/1918.20.224.1 to 18.20.255.25418.20.255.2558,190
16918.21.0.0/1918.21.0.1 to 18.21.31.25418.21.31.2558,190
17018.21.32.0/1918.21.32.1 to 18.21.63.25418.21.63.2558,190
17118.21.64.0/1918.21.64.1 to 18.21.95.25418.21.95.2558,190
17218.21.96.0/1918.21.96.1 to 18.21.127.25418.21.127.2558,190
17318.21.128.0/1918.21.128.1 to 18.21.159.25418.21.159.2558,190
17418.21.160.0/1918.21.160.1 to 18.21.191.25418.21.191.2558,190
17518.21.192.0/1918.21.192.1 to 18.21.223.25418.21.223.2558,190
17618.21.224.0/1918.21.224.1 to 18.21.255.25418.21.255.2558,190
17718.22.0.0/1918.22.0.1 to 18.22.31.25418.22.31.2558,190
17818.22.32.0/1918.22.32.1 to 18.22.63.25418.22.63.2558,190
17918.22.64.0/1918.22.64.1 to 18.22.95.25418.22.95.2558,190
18018.22.96.0/1918.22.96.1 to 18.22.127.25418.22.127.2558,190
18118.22.128.0/1918.22.128.1 to 18.22.159.25418.22.159.2558,190
18218.22.160.0/1918.22.160.1 to 18.22.191.25418.22.191.2558,190
18318.22.192.0/1918.22.192.1 to 18.22.223.25418.22.223.2558,190
18418.22.224.0/1918.22.224.1 to 18.22.255.25418.22.255.2558,190
18518.23.0.0/1918.23.0.1 to 18.23.31.25418.23.31.2558,190
18618.23.32.0/1918.23.32.1 to 18.23.63.25418.23.63.2558,190
18718.23.64.0/1918.23.64.1 to 18.23.95.25418.23.95.2558,190
18818.23.96.0/1918.23.96.1 to 18.23.127.25418.23.127.2558,190
18918.23.128.0/1918.23.128.1 to 18.23.159.25418.23.159.2558,190
19018.23.160.0/1918.23.160.1 to 18.23.191.25418.23.191.2558,190
19118.23.192.0/1918.23.192.1 to 18.23.223.25418.23.223.2558,190
19218.23.224.0/1918.23.224.1 to 18.23.255.25418.23.255.2558,190
19318.24.0.0/1918.24.0.1 to 18.24.31.25418.24.31.2558,190
19418.24.32.0/1918.24.32.1 to 18.24.63.25418.24.63.2558,190
19518.24.64.0/1918.24.64.1 to 18.24.95.25418.24.95.2558,190
19618.24.96.0/1918.24.96.1 to 18.24.127.25418.24.127.2558,190
19718.24.128.0/1918.24.128.1 to 18.24.159.25418.24.159.2558,190
19818.24.160.0/1918.24.160.1 to 18.24.191.25418.24.191.2558,190
19918.24.192.0/1918.24.192.1 to 18.24.223.25418.24.223.2558,190
20018.24.224.0/1918.24.224.1 to 18.24.255.25418.24.255.2558,190
20118.25.0.0/1918.25.0.1 to 18.25.31.25418.25.31.2558,190
20218.25.32.0/1918.25.32.1 to 18.25.63.25418.25.63.2558,190
20318.25.64.0/1918.25.64.1 to 18.25.95.25418.25.95.2558,190
20418.25.96.0/1918.25.96.1 to 18.25.127.25418.25.127.2558,190
20518.25.128.0/1918.25.128.1 to 18.25.159.25418.25.159.2558,190
20618.25.160.0/1918.25.160.1 to 18.25.191.25418.25.191.2558,190
20718.25.192.0/1918.25.192.1 to 18.25.223.25418.25.223.2558,190
20818.25.224.0/1918.25.224.1 to 18.25.255.25418.25.255.2558,190
20918.26.0.0/1918.26.0.1 to 18.26.31.25418.26.31.2558,190
21018.26.32.0/1918.26.32.1 to 18.26.63.25418.26.63.2558,190
21118.26.64.0/1918.26.64.1 to 18.26.95.25418.26.95.2558,190
21218.26.96.0/1918.26.96.1 to 18.26.127.25418.26.127.2558,190
21318.26.128.0/1918.26.128.1 to 18.26.159.25418.26.159.2558,190
21418.26.160.0/1918.26.160.1 to 18.26.191.25418.26.191.2558,190
21518.26.192.0/1918.26.192.1 to 18.26.223.25418.26.223.2558,190
21618.26.224.0/1918.26.224.1 to 18.26.255.25418.26.255.2558,190
21718.27.0.0/1918.27.0.1 to 18.27.31.25418.27.31.2558,190
21818.27.32.0/1918.27.32.1 to 18.27.63.25418.27.63.2558,190
21918.27.64.0/1918.27.64.1 to 18.27.95.25418.27.95.2558,190
22018.27.96.0/1918.27.96.1 to 18.27.127.25418.27.127.2558,190
22118.27.128.0/1918.27.128.1 to 18.27.159.25418.27.159.2558,190
22218.27.160.0/1918.27.160.1 to 18.27.191.25418.27.191.2558,190
22318.27.192.0/1918.27.192.1 to 18.27.223.25418.27.223.2558,190
22418.27.224.0/1918.27.224.1 to 18.27.255.25418.27.255.2558,190
22518.28.0.0/1918.28.0.1 to 18.28.31.25418.28.31.2558,190
22618.28.32.0/1918.28.32.1 to 18.28.63.25418.28.63.2558,190
22718.28.64.0/1918.28.64.1 to 18.28.95.25418.28.95.2558,190
22818.28.96.0/1918.28.96.1 to 18.28.127.25418.28.127.2558,190
22918.28.128.0/1918.28.128.1 to 18.28.159.25418.28.159.2558,190
23018.28.160.0/1918.28.160.1 to 18.28.191.25418.28.191.2558,190
23118.28.192.0/1918.28.192.1 to 18.28.223.25418.28.223.2558,190
23218.28.224.0/1918.28.224.1 to 18.28.255.25418.28.255.2558,190
23318.29.0.0/1918.29.0.1 to 18.29.31.25418.29.31.2558,190
23418.29.32.0/1918.29.32.1 to 18.29.63.25418.29.63.2558,190
23518.29.64.0/1918.29.64.1 to 18.29.95.25418.29.95.2558,190
23618.29.96.0/1918.29.96.1 to 18.29.127.25418.29.127.2558,190
23718.29.128.0/1918.29.128.1 to 18.29.159.25418.29.159.2558,190
23818.29.160.0/1918.29.160.1 to 18.29.191.25418.29.191.2558,190
23918.29.192.0/1918.29.192.1 to 18.29.223.25418.29.223.2558,190
24018.29.224.0/1918.29.224.1 to 18.29.255.25418.29.255.2558,190
24118.30.0.0/1918.30.0.1 to 18.30.31.25418.30.31.2558,190
24218.30.32.0/1918.30.32.1 to 18.30.63.25418.30.63.2558,190
24318.30.64.0/1918.30.64.1 to 18.30.95.25418.30.95.2558,190
24418.30.96.0/1918.30.96.1 to 18.30.127.25418.30.127.2558,190
24518.30.128.0/1918.30.128.1 to 18.30.159.25418.30.159.2558,190
24618.30.160.0/1918.30.160.1 to 18.30.191.25418.30.191.2558,190
24718.30.192.0/1918.30.192.1 to 18.30.223.25418.30.223.2558,190
24818.30.224.0/1918.30.224.1 to 18.30.255.25418.30.255.2558,190
24918.31.0.0/1918.31.0.1 to 18.31.31.25418.31.31.2558,190
25018.31.32.0/1918.31.32.1 to 18.31.63.25418.31.63.2558,190
25118.31.64.0/1918.31.64.1 to 18.31.95.25418.31.95.2558,190
25218.31.96.0/1918.31.96.1 to 18.31.127.25418.31.127.2558,190
25318.31.128.0/1918.31.128.1 to 18.31.159.25418.31.159.2558,190
25418.31.160.0/1918.31.160.1 to 18.31.191.25418.31.191.2558,190
25518.31.192.0/1918.31.192.1 to 18.31.223.25418.31.223.2558,190
25618.31.224.0/1918.31.224.1 to 18.31.255.25418.31.255.2558,190

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.