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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.

Network16.0.0.0/4
Usable hosts268,435,454
Subnet mask240.0.0.0
Addresses268,435,456
Network address
16.0.0.0
Broadcast address
31.255.255.255
First usable
16.0.0.1
Last usable
31.255.255.254
Usable hosts
268,435,454 (268,435,456 less the network and broadcast addresses)
Subnet mask
240.0.0.0
Wildcard mask
15.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/4
Type
Public public
Old class
A (default /8)
As numbers
Hex 10000000 · Integer 268435456 to 536870911
Reverse DNS zones
16.in-addr.arpa
17.in-addr.arpa
18.in-addr.arpa
19.in-addr.arpa
20.in-addr.arpa
21.in-addr.arpa
22.in-addr.arpa
23.in-addr.arpa
24.in-addr.arpa
25.in-addr.arpa
26.in-addr.arpa
27.in-addr.arpa
28.in-addr.arpa
29.in-addr.arpa
30.in-addr.arpa
31.in-addr.arpa
/4 is not on a 8-bit boundary, so it takes 16 /8 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00010000.00000000.00000000.0000000016.0.0.0
Subnet mask11110000.00000000.00000000.00000000240.0.0.0
Network00010000.00000000.00000000.0000000016.0.0.0
Broadcast00011111.11111111.11111111.1111111131.255.255.255
Split into smaller subnets/12
/5 (2)/6 (4)/7 (8)/8 (16)/9 (32)/10 (64)/11 (128)/12 (256)/13 (512)/14 (1,024)/15 (2,048)/16 (4,096)

16.0.0.0/4 makes 256 subnets of /12.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
116.0.0.0/1216.0.0.1 to 16.15.255.25416.15.255.2551,048,574
216.16.0.0/1216.16.0.1 to 16.31.255.25416.31.255.2551,048,574
316.32.0.0/1216.32.0.1 to 16.47.255.25416.47.255.2551,048,574
416.48.0.0/1216.48.0.1 to 16.63.255.25416.63.255.2551,048,574
516.64.0.0/1216.64.0.1 to 16.79.255.25416.79.255.2551,048,574
616.80.0.0/1216.80.0.1 to 16.95.255.25416.95.255.2551,048,574
716.96.0.0/1216.96.0.1 to 16.111.255.25416.111.255.2551,048,574
816.112.0.0/1216.112.0.1 to 16.127.255.25416.127.255.2551,048,574
916.128.0.0/1216.128.0.1 to 16.143.255.25416.143.255.2551,048,574
1016.144.0.0/1216.144.0.1 to 16.159.255.25416.159.255.2551,048,574
1116.160.0.0/1216.160.0.1 to 16.175.255.25416.175.255.2551,048,574
1216.176.0.0/1216.176.0.1 to 16.191.255.25416.191.255.2551,048,574
1316.192.0.0/1216.192.0.1 to 16.207.255.25416.207.255.2551,048,574
1416.208.0.0/1216.208.0.1 to 16.223.255.25416.223.255.2551,048,574
1516.224.0.0/1216.224.0.1 to 16.239.255.25416.239.255.2551,048,574
1616.240.0.0/1216.240.0.1 to 16.255.255.25416.255.255.2551,048,574
1717.0.0.0/1217.0.0.1 to 17.15.255.25417.15.255.2551,048,574
1817.16.0.0/1217.16.0.1 to 17.31.255.25417.31.255.2551,048,574
1917.32.0.0/1217.32.0.1 to 17.47.255.25417.47.255.2551,048,574
2017.48.0.0/1217.48.0.1 to 17.63.255.25417.63.255.2551,048,574
2117.64.0.0/1217.64.0.1 to 17.79.255.25417.79.255.2551,048,574
2217.80.0.0/1217.80.0.1 to 17.95.255.25417.95.255.2551,048,574
2317.96.0.0/1217.96.0.1 to 17.111.255.25417.111.255.2551,048,574
2417.112.0.0/1217.112.0.1 to 17.127.255.25417.127.255.2551,048,574
2517.128.0.0/1217.128.0.1 to 17.143.255.25417.143.255.2551,048,574
2617.144.0.0/1217.144.0.1 to 17.159.255.25417.159.255.2551,048,574
2717.160.0.0/1217.160.0.1 to 17.175.255.25417.175.255.2551,048,574
2817.176.0.0/1217.176.0.1 to 17.191.255.25417.191.255.2551,048,574
2917.192.0.0/1217.192.0.1 to 17.207.255.25417.207.255.2551,048,574
3017.208.0.0/1217.208.0.1 to 17.223.255.25417.223.255.2551,048,574
3117.224.0.0/1217.224.0.1 to 17.239.255.25417.239.255.2551,048,574
3217.240.0.0/1217.240.0.1 to 17.255.255.25417.255.255.2551,048,574
3318.0.0.0/1218.0.0.1 to 18.15.255.25418.15.255.2551,048,574
3418.16.0.0/1218.16.0.1 to 18.31.255.25418.31.255.2551,048,574
3518.32.0.0/1218.32.0.1 to 18.47.255.25418.47.255.2551,048,574
3618.48.0.0/1218.48.0.1 to 18.63.255.25418.63.255.2551,048,574
3718.64.0.0/1218.64.0.1 to 18.79.255.25418.79.255.2551,048,574
3818.80.0.0/1218.80.0.1 to 18.95.255.25418.95.255.2551,048,574
3918.96.0.0/1218.96.0.1 to 18.111.255.25418.111.255.2551,048,574
4018.112.0.0/1218.112.0.1 to 18.127.255.25418.127.255.2551,048,574
4118.128.0.0/1218.128.0.1 to 18.143.255.25418.143.255.2551,048,574
4218.144.0.0/1218.144.0.1 to 18.159.255.25418.159.255.2551,048,574
4318.160.0.0/1218.160.0.1 to 18.175.255.25418.175.255.2551,048,574
4418.176.0.0/1218.176.0.1 to 18.191.255.25418.191.255.2551,048,574
4518.192.0.0/1218.192.0.1 to 18.207.255.25418.207.255.2551,048,574
4618.208.0.0/1218.208.0.1 to 18.223.255.25418.223.255.2551,048,574
4718.224.0.0/1218.224.0.1 to 18.239.255.25418.239.255.2551,048,574
4818.240.0.0/1218.240.0.1 to 18.255.255.25418.255.255.2551,048,574
4919.0.0.0/1219.0.0.1 to 19.15.255.25419.15.255.2551,048,574
5019.16.0.0/1219.16.0.1 to 19.31.255.25419.31.255.2551,048,574
5119.32.0.0/1219.32.0.1 to 19.47.255.25419.47.255.2551,048,574
5219.48.0.0/1219.48.0.1 to 19.63.255.25419.63.255.2551,048,574
5319.64.0.0/1219.64.0.1 to 19.79.255.25419.79.255.2551,048,574
5419.80.0.0/1219.80.0.1 to 19.95.255.25419.95.255.2551,048,574
5519.96.0.0/1219.96.0.1 to 19.111.255.25419.111.255.2551,048,574
5619.112.0.0/1219.112.0.1 to 19.127.255.25419.127.255.2551,048,574
5719.128.0.0/1219.128.0.1 to 19.143.255.25419.143.255.2551,048,574
5819.144.0.0/1219.144.0.1 to 19.159.255.25419.159.255.2551,048,574
5919.160.0.0/1219.160.0.1 to 19.175.255.25419.175.255.2551,048,574
6019.176.0.0/1219.176.0.1 to 19.191.255.25419.191.255.2551,048,574
6119.192.0.0/1219.192.0.1 to 19.207.255.25419.207.255.2551,048,574
6219.208.0.0/1219.208.0.1 to 19.223.255.25419.223.255.2551,048,574
6319.224.0.0/1219.224.0.1 to 19.239.255.25419.239.255.2551,048,574
6419.240.0.0/1219.240.0.1 to 19.255.255.25419.255.255.2551,048,574
6520.0.0.0/1220.0.0.1 to 20.15.255.25420.15.255.2551,048,574
6620.16.0.0/1220.16.0.1 to 20.31.255.25420.31.255.2551,048,574
6720.32.0.0/1220.32.0.1 to 20.47.255.25420.47.255.2551,048,574
6820.48.0.0/1220.48.0.1 to 20.63.255.25420.63.255.2551,048,574
6920.64.0.0/1220.64.0.1 to 20.79.255.25420.79.255.2551,048,574
7020.80.0.0/1220.80.0.1 to 20.95.255.25420.95.255.2551,048,574
7120.96.0.0/1220.96.0.1 to 20.111.255.25420.111.255.2551,048,574
7220.112.0.0/1220.112.0.1 to 20.127.255.25420.127.255.2551,048,574
7320.128.0.0/1220.128.0.1 to 20.143.255.25420.143.255.2551,048,574
7420.144.0.0/1220.144.0.1 to 20.159.255.25420.159.255.2551,048,574
7520.160.0.0/1220.160.0.1 to 20.175.255.25420.175.255.2551,048,574
7620.176.0.0/1220.176.0.1 to 20.191.255.25420.191.255.2551,048,574
7720.192.0.0/1220.192.0.1 to 20.207.255.25420.207.255.2551,048,574
7820.208.0.0/1220.208.0.1 to 20.223.255.25420.223.255.2551,048,574
7920.224.0.0/1220.224.0.1 to 20.239.255.25420.239.255.2551,048,574
8020.240.0.0/1220.240.0.1 to 20.255.255.25420.255.255.2551,048,574
8121.0.0.0/1221.0.0.1 to 21.15.255.25421.15.255.2551,048,574
8221.16.0.0/1221.16.0.1 to 21.31.255.25421.31.255.2551,048,574
8321.32.0.0/1221.32.0.1 to 21.47.255.25421.47.255.2551,048,574
8421.48.0.0/1221.48.0.1 to 21.63.255.25421.63.255.2551,048,574
8521.64.0.0/1221.64.0.1 to 21.79.255.25421.79.255.2551,048,574
8621.80.0.0/1221.80.0.1 to 21.95.255.25421.95.255.2551,048,574
8721.96.0.0/1221.96.0.1 to 21.111.255.25421.111.255.2551,048,574
8821.112.0.0/1221.112.0.1 to 21.127.255.25421.127.255.2551,048,574
8921.128.0.0/1221.128.0.1 to 21.143.255.25421.143.255.2551,048,574
9021.144.0.0/1221.144.0.1 to 21.159.255.25421.159.255.2551,048,574
9121.160.0.0/1221.160.0.1 to 21.175.255.25421.175.255.2551,048,574
9221.176.0.0/1221.176.0.1 to 21.191.255.25421.191.255.2551,048,574
9321.192.0.0/1221.192.0.1 to 21.207.255.25421.207.255.2551,048,574
9421.208.0.0/1221.208.0.1 to 21.223.255.25421.223.255.2551,048,574
9521.224.0.0/1221.224.0.1 to 21.239.255.25421.239.255.2551,048,574
9621.240.0.0/1221.240.0.1 to 21.255.255.25421.255.255.2551,048,574
9722.0.0.0/1222.0.0.1 to 22.15.255.25422.15.255.2551,048,574
9822.16.0.0/1222.16.0.1 to 22.31.255.25422.31.255.2551,048,574
9922.32.0.0/1222.32.0.1 to 22.47.255.25422.47.255.2551,048,574
10022.48.0.0/1222.48.0.1 to 22.63.255.25422.63.255.2551,048,574
10122.64.0.0/1222.64.0.1 to 22.79.255.25422.79.255.2551,048,574
10222.80.0.0/1222.80.0.1 to 22.95.255.25422.95.255.2551,048,574
10322.96.0.0/1222.96.0.1 to 22.111.255.25422.111.255.2551,048,574
10422.112.0.0/1222.112.0.1 to 22.127.255.25422.127.255.2551,048,574
10522.128.0.0/1222.128.0.1 to 22.143.255.25422.143.255.2551,048,574
10622.144.0.0/1222.144.0.1 to 22.159.255.25422.159.255.2551,048,574
10722.160.0.0/1222.160.0.1 to 22.175.255.25422.175.255.2551,048,574
10822.176.0.0/1222.176.0.1 to 22.191.255.25422.191.255.2551,048,574
10922.192.0.0/1222.192.0.1 to 22.207.255.25422.207.255.2551,048,574
11022.208.0.0/1222.208.0.1 to 22.223.255.25422.223.255.2551,048,574
11122.224.0.0/1222.224.0.1 to 22.239.255.25422.239.255.2551,048,574
11222.240.0.0/1222.240.0.1 to 22.255.255.25422.255.255.2551,048,574
11323.0.0.0/1223.0.0.1 to 23.15.255.25423.15.255.2551,048,574
11423.16.0.0/1223.16.0.1 to 23.31.255.25423.31.255.2551,048,574
11523.32.0.0/1223.32.0.1 to 23.47.255.25423.47.255.2551,048,574
11623.48.0.0/1223.48.0.1 to 23.63.255.25423.63.255.2551,048,574
11723.64.0.0/1223.64.0.1 to 23.79.255.25423.79.255.2551,048,574
11823.80.0.0/1223.80.0.1 to 23.95.255.25423.95.255.2551,048,574
11923.96.0.0/1223.96.0.1 to 23.111.255.25423.111.255.2551,048,574
12023.112.0.0/1223.112.0.1 to 23.127.255.25423.127.255.2551,048,574
12123.128.0.0/1223.128.0.1 to 23.143.255.25423.143.255.2551,048,574
12223.144.0.0/1223.144.0.1 to 23.159.255.25423.159.255.2551,048,574
12323.160.0.0/1223.160.0.1 to 23.175.255.25423.175.255.2551,048,574
12423.176.0.0/1223.176.0.1 to 23.191.255.25423.191.255.2551,048,574
12523.192.0.0/1223.192.0.1 to 23.207.255.25423.207.255.2551,048,574
12623.208.0.0/1223.208.0.1 to 23.223.255.25423.223.255.2551,048,574
12723.224.0.0/1223.224.0.1 to 23.239.255.25423.239.255.2551,048,574
12823.240.0.0/1223.240.0.1 to 23.255.255.25423.255.255.2551,048,574
12924.0.0.0/1224.0.0.1 to 24.15.255.25424.15.255.2551,048,574
13024.16.0.0/1224.16.0.1 to 24.31.255.25424.31.255.2551,048,574
13124.32.0.0/1224.32.0.1 to 24.47.255.25424.47.255.2551,048,574
13224.48.0.0/1224.48.0.1 to 24.63.255.25424.63.255.2551,048,574
13324.64.0.0/1224.64.0.1 to 24.79.255.25424.79.255.2551,048,574
13424.80.0.0/1224.80.0.1 to 24.95.255.25424.95.255.2551,048,574
13524.96.0.0/1224.96.0.1 to 24.111.255.25424.111.255.2551,048,574
13624.112.0.0/1224.112.0.1 to 24.127.255.25424.127.255.2551,048,574
13724.128.0.0/1224.128.0.1 to 24.143.255.25424.143.255.2551,048,574
13824.144.0.0/1224.144.0.1 to 24.159.255.25424.159.255.2551,048,574
13924.160.0.0/1224.160.0.1 to 24.175.255.25424.175.255.2551,048,574
14024.176.0.0/1224.176.0.1 to 24.191.255.25424.191.255.2551,048,574
14124.192.0.0/1224.192.0.1 to 24.207.255.25424.207.255.2551,048,574
14224.208.0.0/1224.208.0.1 to 24.223.255.25424.223.255.2551,048,574
14324.224.0.0/1224.224.0.1 to 24.239.255.25424.239.255.2551,048,574
14424.240.0.0/1224.240.0.1 to 24.255.255.25424.255.255.2551,048,574
14525.0.0.0/1225.0.0.1 to 25.15.255.25425.15.255.2551,048,574
14625.16.0.0/1225.16.0.1 to 25.31.255.25425.31.255.2551,048,574
14725.32.0.0/1225.32.0.1 to 25.47.255.25425.47.255.2551,048,574
14825.48.0.0/1225.48.0.1 to 25.63.255.25425.63.255.2551,048,574
14925.64.0.0/1225.64.0.1 to 25.79.255.25425.79.255.2551,048,574
15025.80.0.0/1225.80.0.1 to 25.95.255.25425.95.255.2551,048,574
15125.96.0.0/1225.96.0.1 to 25.111.255.25425.111.255.2551,048,574
15225.112.0.0/1225.112.0.1 to 25.127.255.25425.127.255.2551,048,574
15325.128.0.0/1225.128.0.1 to 25.143.255.25425.143.255.2551,048,574
15425.144.0.0/1225.144.0.1 to 25.159.255.25425.159.255.2551,048,574
15525.160.0.0/1225.160.0.1 to 25.175.255.25425.175.255.2551,048,574
15625.176.0.0/1225.176.0.1 to 25.191.255.25425.191.255.2551,048,574
15725.192.0.0/1225.192.0.1 to 25.207.255.25425.207.255.2551,048,574
15825.208.0.0/1225.208.0.1 to 25.223.255.25425.223.255.2551,048,574
15925.224.0.0/1225.224.0.1 to 25.239.255.25425.239.255.2551,048,574
16025.240.0.0/1225.240.0.1 to 25.255.255.25425.255.255.2551,048,574
16126.0.0.0/1226.0.0.1 to 26.15.255.25426.15.255.2551,048,574
16226.16.0.0/1226.16.0.1 to 26.31.255.25426.31.255.2551,048,574
16326.32.0.0/1226.32.0.1 to 26.47.255.25426.47.255.2551,048,574
16426.48.0.0/1226.48.0.1 to 26.63.255.25426.63.255.2551,048,574
16526.64.0.0/1226.64.0.1 to 26.79.255.25426.79.255.2551,048,574
16626.80.0.0/1226.80.0.1 to 26.95.255.25426.95.255.2551,048,574
16726.96.0.0/1226.96.0.1 to 26.111.255.25426.111.255.2551,048,574
16826.112.0.0/1226.112.0.1 to 26.127.255.25426.127.255.2551,048,574
16926.128.0.0/1226.128.0.1 to 26.143.255.25426.143.255.2551,048,574
17026.144.0.0/1226.144.0.1 to 26.159.255.25426.159.255.2551,048,574
17126.160.0.0/1226.160.0.1 to 26.175.255.25426.175.255.2551,048,574
17226.176.0.0/1226.176.0.1 to 26.191.255.25426.191.255.2551,048,574
17326.192.0.0/1226.192.0.1 to 26.207.255.25426.207.255.2551,048,574
17426.208.0.0/1226.208.0.1 to 26.223.255.25426.223.255.2551,048,574
17526.224.0.0/1226.224.0.1 to 26.239.255.25426.239.255.2551,048,574
17626.240.0.0/1226.240.0.1 to 26.255.255.25426.255.255.2551,048,574
17727.0.0.0/1227.0.0.1 to 27.15.255.25427.15.255.2551,048,574
17827.16.0.0/1227.16.0.1 to 27.31.255.25427.31.255.2551,048,574
17927.32.0.0/1227.32.0.1 to 27.47.255.25427.47.255.2551,048,574
18027.48.0.0/1227.48.0.1 to 27.63.255.25427.63.255.2551,048,574
18127.64.0.0/1227.64.0.1 to 27.79.255.25427.79.255.2551,048,574
18227.80.0.0/1227.80.0.1 to 27.95.255.25427.95.255.2551,048,574
18327.96.0.0/1227.96.0.1 to 27.111.255.25427.111.255.2551,048,574
18427.112.0.0/1227.112.0.1 to 27.127.255.25427.127.255.2551,048,574
18527.128.0.0/1227.128.0.1 to 27.143.255.25427.143.255.2551,048,574
18627.144.0.0/1227.144.0.1 to 27.159.255.25427.159.255.2551,048,574
18727.160.0.0/1227.160.0.1 to 27.175.255.25427.175.255.2551,048,574
18827.176.0.0/1227.176.0.1 to 27.191.255.25427.191.255.2551,048,574
18927.192.0.0/1227.192.0.1 to 27.207.255.25427.207.255.2551,048,574
19027.208.0.0/1227.208.0.1 to 27.223.255.25427.223.255.2551,048,574
19127.224.0.0/1227.224.0.1 to 27.239.255.25427.239.255.2551,048,574
19227.240.0.0/1227.240.0.1 to 27.255.255.25427.255.255.2551,048,574
19328.0.0.0/1228.0.0.1 to 28.15.255.25428.15.255.2551,048,574
19428.16.0.0/1228.16.0.1 to 28.31.255.25428.31.255.2551,048,574
19528.32.0.0/1228.32.0.1 to 28.47.255.25428.47.255.2551,048,574
19628.48.0.0/1228.48.0.1 to 28.63.255.25428.63.255.2551,048,574
19728.64.0.0/1228.64.0.1 to 28.79.255.25428.79.255.2551,048,574
19828.80.0.0/1228.80.0.1 to 28.95.255.25428.95.255.2551,048,574
19928.96.0.0/1228.96.0.1 to 28.111.255.25428.111.255.2551,048,574
20028.112.0.0/1228.112.0.1 to 28.127.255.25428.127.255.2551,048,574
20128.128.0.0/1228.128.0.1 to 28.143.255.25428.143.255.2551,048,574
20228.144.0.0/1228.144.0.1 to 28.159.255.25428.159.255.2551,048,574
20328.160.0.0/1228.160.0.1 to 28.175.255.25428.175.255.2551,048,574
20428.176.0.0/1228.176.0.1 to 28.191.255.25428.191.255.2551,048,574
20528.192.0.0/1228.192.0.1 to 28.207.255.25428.207.255.2551,048,574
20628.208.0.0/1228.208.0.1 to 28.223.255.25428.223.255.2551,048,574
20728.224.0.0/1228.224.0.1 to 28.239.255.25428.239.255.2551,048,574
20828.240.0.0/1228.240.0.1 to 28.255.255.25428.255.255.2551,048,574
20929.0.0.0/1229.0.0.1 to 29.15.255.25429.15.255.2551,048,574
21029.16.0.0/1229.16.0.1 to 29.31.255.25429.31.255.2551,048,574
21129.32.0.0/1229.32.0.1 to 29.47.255.25429.47.255.2551,048,574
21229.48.0.0/1229.48.0.1 to 29.63.255.25429.63.255.2551,048,574
21329.64.0.0/1229.64.0.1 to 29.79.255.25429.79.255.2551,048,574
21429.80.0.0/1229.80.0.1 to 29.95.255.25429.95.255.2551,048,574
21529.96.0.0/1229.96.0.1 to 29.111.255.25429.111.255.2551,048,574
21629.112.0.0/1229.112.0.1 to 29.127.255.25429.127.255.2551,048,574
21729.128.0.0/1229.128.0.1 to 29.143.255.25429.143.255.2551,048,574
21829.144.0.0/1229.144.0.1 to 29.159.255.25429.159.255.2551,048,574
21929.160.0.0/1229.160.0.1 to 29.175.255.25429.175.255.2551,048,574
22029.176.0.0/1229.176.0.1 to 29.191.255.25429.191.255.2551,048,574
22129.192.0.0/1229.192.0.1 to 29.207.255.25429.207.255.2551,048,574
22229.208.0.0/1229.208.0.1 to 29.223.255.25429.223.255.2551,048,574
22329.224.0.0/1229.224.0.1 to 29.239.255.25429.239.255.2551,048,574
22429.240.0.0/1229.240.0.1 to 29.255.255.25429.255.255.2551,048,574
22530.0.0.0/1230.0.0.1 to 30.15.255.25430.15.255.2551,048,574
22630.16.0.0/1230.16.0.1 to 30.31.255.25430.31.255.2551,048,574
22730.32.0.0/1230.32.0.1 to 30.47.255.25430.47.255.2551,048,574
22830.48.0.0/1230.48.0.1 to 30.63.255.25430.63.255.2551,048,574
22930.64.0.0/1230.64.0.1 to 30.79.255.25430.79.255.2551,048,574
23030.80.0.0/1230.80.0.1 to 30.95.255.25430.95.255.2551,048,574
23130.96.0.0/1230.96.0.1 to 30.111.255.25430.111.255.2551,048,574
23230.112.0.0/1230.112.0.1 to 30.127.255.25430.127.255.2551,048,574
23330.128.0.0/1230.128.0.1 to 30.143.255.25430.143.255.2551,048,574
23430.144.0.0/1230.144.0.1 to 30.159.255.25430.159.255.2551,048,574
23530.160.0.0/1230.160.0.1 to 30.175.255.25430.175.255.2551,048,574
23630.176.0.0/1230.176.0.1 to 30.191.255.25430.191.255.2551,048,574
23730.192.0.0/1230.192.0.1 to 30.207.255.25430.207.255.2551,048,574
23830.208.0.0/1230.208.0.1 to 30.223.255.25430.223.255.2551,048,574
23930.224.0.0/1230.224.0.1 to 30.239.255.25430.239.255.2551,048,574
24030.240.0.0/1230.240.0.1 to 30.255.255.25430.255.255.2551,048,574
24131.0.0.0/1231.0.0.1 to 31.15.255.25431.15.255.2551,048,574
24231.16.0.0/1231.16.0.1 to 31.31.255.25431.31.255.2551,048,574
24331.32.0.0/1231.32.0.1 to 31.47.255.25431.47.255.2551,048,574
24431.48.0.0/1231.48.0.1 to 31.63.255.25431.63.255.2551,048,574
24531.64.0.0/1231.64.0.1 to 31.79.255.25431.79.255.2551,048,574
24631.80.0.0/1231.80.0.1 to 31.95.255.25431.95.255.2551,048,574
24731.96.0.0/1231.96.0.1 to 31.111.255.25431.111.255.2551,048,574
24831.112.0.0/1231.112.0.1 to 31.127.255.25431.127.255.2551,048,574
24931.128.0.0/1231.128.0.1 to 31.143.255.25431.143.255.2551,048,574
25031.144.0.0/1231.144.0.1 to 31.159.255.25431.159.255.2551,048,574
25131.160.0.0/1231.160.0.1 to 31.175.255.25431.175.255.2551,048,574
25231.176.0.0/1231.176.0.1 to 31.191.255.25431.191.255.2551,048,574
25331.192.0.0/1231.192.0.1 to 31.207.255.25431.207.255.2551,048,574
25431.208.0.0/1231.208.0.1 to 31.223.255.25431.223.255.2551,048,574
25531.224.0.0/1231.224.0.1 to 31.239.255.25431.239.255.2551,048,574
25631.240.0.0/1231.240.0.1 to 31.255.255.25431.255.255.2551,048,574

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.