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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.

Network4.64.0.0/12
Usable hosts1,048,574
Subnet mask255.240.0.0
Addresses1,048,576
Network address
4.64.0.0
Broadcast address
4.79.255.255
First usable
4.64.0.1
Last usable
4.79.255.254
Usable hosts
1,048,574 (1,048,576 less the network and broadcast addresses)
Subnet mask
255.240.0.0
Wildcard mask
0.15.255.255 (Cisco ACLs, OSPF)
Prefix length
/12
Type
Public public
Old class
A (default /8)
As numbers
Hex 04400000 · Integer 71303168 to 72351743
Reverse DNS zones
64.4.in-addr.arpa
65.4.in-addr.arpa
66.4.in-addr.arpa
67.4.in-addr.arpa
68.4.in-addr.arpa
69.4.in-addr.arpa
70.4.in-addr.arpa
71.4.in-addr.arpa
72.4.in-addr.arpa
73.4.in-addr.arpa
74.4.in-addr.arpa
75.4.in-addr.arpa
76.4.in-addr.arpa
77.4.in-addr.arpa
78.4.in-addr.arpa
79.4.in-addr.arpa
/12 is not on a 8-bit boundary, so it takes 16 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00000100.01000000.00000000.000000004.64.0.0
Subnet mask11111111.11110000.00000000.00000000255.240.0.0
Network00000100.01000000.00000000.000000004.64.0.0
Broadcast00000100.01001111.11111111.111111114.79.255.255
Split into smaller subnets/21
/13 (2)/14 (4)/15 (8)/16 (16)/17 (32)/18 (64)/19 (128)/20 (256)/21 (512)/22 (1,024)/23 (2,048)/24 (4,096)

4.64.0.0/12 makes 512 subnets of /21; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
14.64.0.0/214.64.0.1 to 4.64.7.2544.64.7.2552,046
24.64.8.0/214.64.8.1 to 4.64.15.2544.64.15.2552,046
34.64.16.0/214.64.16.1 to 4.64.23.2544.64.23.2552,046
44.64.24.0/214.64.24.1 to 4.64.31.2544.64.31.2552,046
54.64.32.0/214.64.32.1 to 4.64.39.2544.64.39.2552,046
64.64.40.0/214.64.40.1 to 4.64.47.2544.64.47.2552,046
74.64.48.0/214.64.48.1 to 4.64.55.2544.64.55.2552,046
84.64.56.0/214.64.56.1 to 4.64.63.2544.64.63.2552,046
94.64.64.0/214.64.64.1 to 4.64.71.2544.64.71.2552,046
104.64.72.0/214.64.72.1 to 4.64.79.2544.64.79.2552,046
114.64.80.0/214.64.80.1 to 4.64.87.2544.64.87.2552,046
124.64.88.0/214.64.88.1 to 4.64.95.2544.64.95.2552,046
134.64.96.0/214.64.96.1 to 4.64.103.2544.64.103.2552,046
144.64.104.0/214.64.104.1 to 4.64.111.2544.64.111.2552,046
154.64.112.0/214.64.112.1 to 4.64.119.2544.64.119.2552,046
164.64.120.0/214.64.120.1 to 4.64.127.2544.64.127.2552,046
174.64.128.0/214.64.128.1 to 4.64.135.2544.64.135.2552,046
184.64.136.0/214.64.136.1 to 4.64.143.2544.64.143.2552,046
194.64.144.0/214.64.144.1 to 4.64.151.2544.64.151.2552,046
204.64.152.0/214.64.152.1 to 4.64.159.2544.64.159.2552,046
214.64.160.0/214.64.160.1 to 4.64.167.2544.64.167.2552,046
224.64.168.0/214.64.168.1 to 4.64.175.2544.64.175.2552,046
234.64.176.0/214.64.176.1 to 4.64.183.2544.64.183.2552,046
244.64.184.0/214.64.184.1 to 4.64.191.2544.64.191.2552,046
254.64.192.0/214.64.192.1 to 4.64.199.2544.64.199.2552,046
264.64.200.0/214.64.200.1 to 4.64.207.2544.64.207.2552,046
274.64.208.0/214.64.208.1 to 4.64.215.2544.64.215.2552,046
284.64.216.0/214.64.216.1 to 4.64.223.2544.64.223.2552,046
294.64.224.0/214.64.224.1 to 4.64.231.2544.64.231.2552,046
304.64.232.0/214.64.232.1 to 4.64.239.2544.64.239.2552,046
314.64.240.0/214.64.240.1 to 4.64.247.2544.64.247.2552,046
324.64.248.0/214.64.248.1 to 4.64.255.2544.64.255.2552,046
334.65.0.0/214.65.0.1 to 4.65.7.2544.65.7.2552,046
344.65.8.0/214.65.8.1 to 4.65.15.2544.65.15.2552,046
354.65.16.0/214.65.16.1 to 4.65.23.2544.65.23.2552,046
364.65.24.0/214.65.24.1 to 4.65.31.2544.65.31.2552,046
374.65.32.0/214.65.32.1 to 4.65.39.2544.65.39.2552,046
384.65.40.0/214.65.40.1 to 4.65.47.2544.65.47.2552,046
394.65.48.0/214.65.48.1 to 4.65.55.2544.65.55.2552,046
404.65.56.0/214.65.56.1 to 4.65.63.2544.65.63.2552,046
414.65.64.0/214.65.64.1 to 4.65.71.2544.65.71.2552,046
424.65.72.0/214.65.72.1 to 4.65.79.2544.65.79.2552,046
434.65.80.0/214.65.80.1 to 4.65.87.2544.65.87.2552,046
444.65.88.0/214.65.88.1 to 4.65.95.2544.65.95.2552,046
454.65.96.0/214.65.96.1 to 4.65.103.2544.65.103.2552,046
464.65.104.0/214.65.104.1 to 4.65.111.2544.65.111.2552,046
474.65.112.0/214.65.112.1 to 4.65.119.2544.65.119.2552,046
484.65.120.0/214.65.120.1 to 4.65.127.2544.65.127.2552,046
494.65.128.0/214.65.128.1 to 4.65.135.2544.65.135.2552,046
504.65.136.0/214.65.136.1 to 4.65.143.2544.65.143.2552,046
514.65.144.0/214.65.144.1 to 4.65.151.2544.65.151.2552,046
524.65.152.0/214.65.152.1 to 4.65.159.2544.65.159.2552,046
534.65.160.0/214.65.160.1 to 4.65.167.2544.65.167.2552,046
544.65.168.0/214.65.168.1 to 4.65.175.2544.65.175.2552,046
554.65.176.0/214.65.176.1 to 4.65.183.2544.65.183.2552,046
564.65.184.0/214.65.184.1 to 4.65.191.2544.65.191.2552,046
574.65.192.0/214.65.192.1 to 4.65.199.2544.65.199.2552,046
584.65.200.0/214.65.200.1 to 4.65.207.2544.65.207.2552,046
594.65.208.0/214.65.208.1 to 4.65.215.2544.65.215.2552,046
604.65.216.0/214.65.216.1 to 4.65.223.2544.65.223.2552,046
614.65.224.0/214.65.224.1 to 4.65.231.2544.65.231.2552,046
624.65.232.0/214.65.232.1 to 4.65.239.2544.65.239.2552,046
634.65.240.0/214.65.240.1 to 4.65.247.2544.65.247.2552,046
644.65.248.0/214.65.248.1 to 4.65.255.2544.65.255.2552,046
654.66.0.0/214.66.0.1 to 4.66.7.2544.66.7.2552,046
664.66.8.0/214.66.8.1 to 4.66.15.2544.66.15.2552,046
674.66.16.0/214.66.16.1 to 4.66.23.2544.66.23.2552,046
684.66.24.0/214.66.24.1 to 4.66.31.2544.66.31.2552,046
694.66.32.0/214.66.32.1 to 4.66.39.2544.66.39.2552,046
704.66.40.0/214.66.40.1 to 4.66.47.2544.66.47.2552,046
714.66.48.0/214.66.48.1 to 4.66.55.2544.66.55.2552,046
724.66.56.0/214.66.56.1 to 4.66.63.2544.66.63.2552,046
734.66.64.0/214.66.64.1 to 4.66.71.2544.66.71.2552,046
744.66.72.0/214.66.72.1 to 4.66.79.2544.66.79.2552,046
754.66.80.0/214.66.80.1 to 4.66.87.2544.66.87.2552,046
764.66.88.0/214.66.88.1 to 4.66.95.2544.66.95.2552,046
774.66.96.0/214.66.96.1 to 4.66.103.2544.66.103.2552,046
784.66.104.0/214.66.104.1 to 4.66.111.2544.66.111.2552,046
794.66.112.0/214.66.112.1 to 4.66.119.2544.66.119.2552,046
804.66.120.0/214.66.120.1 to 4.66.127.2544.66.127.2552,046
814.66.128.0/214.66.128.1 to 4.66.135.2544.66.135.2552,046
824.66.136.0/214.66.136.1 to 4.66.143.2544.66.143.2552,046
834.66.144.0/214.66.144.1 to 4.66.151.2544.66.151.2552,046
844.66.152.0/214.66.152.1 to 4.66.159.2544.66.159.2552,046
854.66.160.0/214.66.160.1 to 4.66.167.2544.66.167.2552,046
864.66.168.0/214.66.168.1 to 4.66.175.2544.66.175.2552,046
874.66.176.0/214.66.176.1 to 4.66.183.2544.66.183.2552,046
884.66.184.0/214.66.184.1 to 4.66.191.2544.66.191.2552,046
894.66.192.0/214.66.192.1 to 4.66.199.2544.66.199.2552,046
904.66.200.0/214.66.200.1 to 4.66.207.2544.66.207.2552,046
914.66.208.0/214.66.208.1 to 4.66.215.2544.66.215.2552,046
924.66.216.0/214.66.216.1 to 4.66.223.2544.66.223.2552,046
934.66.224.0/214.66.224.1 to 4.66.231.2544.66.231.2552,046
944.66.232.0/214.66.232.1 to 4.66.239.2544.66.239.2552,046
954.66.240.0/214.66.240.1 to 4.66.247.2544.66.247.2552,046
964.66.248.0/214.66.248.1 to 4.66.255.2544.66.255.2552,046
974.67.0.0/214.67.0.1 to 4.67.7.2544.67.7.2552,046
984.67.8.0/214.67.8.1 to 4.67.15.2544.67.15.2552,046
994.67.16.0/214.67.16.1 to 4.67.23.2544.67.23.2552,046
1004.67.24.0/214.67.24.1 to 4.67.31.2544.67.31.2552,046
1014.67.32.0/214.67.32.1 to 4.67.39.2544.67.39.2552,046
1024.67.40.0/214.67.40.1 to 4.67.47.2544.67.47.2552,046
1034.67.48.0/214.67.48.1 to 4.67.55.2544.67.55.2552,046
1044.67.56.0/214.67.56.1 to 4.67.63.2544.67.63.2552,046
1054.67.64.0/214.67.64.1 to 4.67.71.2544.67.71.2552,046
1064.67.72.0/214.67.72.1 to 4.67.79.2544.67.79.2552,046
1074.67.80.0/214.67.80.1 to 4.67.87.2544.67.87.2552,046
1084.67.88.0/214.67.88.1 to 4.67.95.2544.67.95.2552,046
1094.67.96.0/214.67.96.1 to 4.67.103.2544.67.103.2552,046
1104.67.104.0/214.67.104.1 to 4.67.111.2544.67.111.2552,046
1114.67.112.0/214.67.112.1 to 4.67.119.2544.67.119.2552,046
1124.67.120.0/214.67.120.1 to 4.67.127.2544.67.127.2552,046
1134.67.128.0/214.67.128.1 to 4.67.135.2544.67.135.2552,046
1144.67.136.0/214.67.136.1 to 4.67.143.2544.67.143.2552,046
1154.67.144.0/214.67.144.1 to 4.67.151.2544.67.151.2552,046
1164.67.152.0/214.67.152.1 to 4.67.159.2544.67.159.2552,046
1174.67.160.0/214.67.160.1 to 4.67.167.2544.67.167.2552,046
1184.67.168.0/214.67.168.1 to 4.67.175.2544.67.175.2552,046
1194.67.176.0/214.67.176.1 to 4.67.183.2544.67.183.2552,046
1204.67.184.0/214.67.184.1 to 4.67.191.2544.67.191.2552,046
1214.67.192.0/214.67.192.1 to 4.67.199.2544.67.199.2552,046
1224.67.200.0/214.67.200.1 to 4.67.207.2544.67.207.2552,046
1234.67.208.0/214.67.208.1 to 4.67.215.2544.67.215.2552,046
1244.67.216.0/214.67.216.1 to 4.67.223.2544.67.223.2552,046
1254.67.224.0/214.67.224.1 to 4.67.231.2544.67.231.2552,046
1264.67.232.0/214.67.232.1 to 4.67.239.2544.67.239.2552,046
1274.67.240.0/214.67.240.1 to 4.67.247.2544.67.247.2552,046
1284.67.248.0/214.67.248.1 to 4.67.255.2544.67.255.2552,046
1294.68.0.0/214.68.0.1 to 4.68.7.2544.68.7.2552,046
1304.68.8.0/214.68.8.1 to 4.68.15.2544.68.15.2552,046
1314.68.16.0/214.68.16.1 to 4.68.23.2544.68.23.2552,046
1324.68.24.0/214.68.24.1 to 4.68.31.2544.68.31.2552,046
1334.68.32.0/214.68.32.1 to 4.68.39.2544.68.39.2552,046
1344.68.40.0/214.68.40.1 to 4.68.47.2544.68.47.2552,046
1354.68.48.0/214.68.48.1 to 4.68.55.2544.68.55.2552,046
1364.68.56.0/214.68.56.1 to 4.68.63.2544.68.63.2552,046
1374.68.64.0/214.68.64.1 to 4.68.71.2544.68.71.2552,046
1384.68.72.0/214.68.72.1 to 4.68.79.2544.68.79.2552,046
1394.68.80.0/214.68.80.1 to 4.68.87.2544.68.87.2552,046
1404.68.88.0/214.68.88.1 to 4.68.95.2544.68.95.2552,046
1414.68.96.0/214.68.96.1 to 4.68.103.2544.68.103.2552,046
1424.68.104.0/214.68.104.1 to 4.68.111.2544.68.111.2552,046
1434.68.112.0/214.68.112.1 to 4.68.119.2544.68.119.2552,046
1444.68.120.0/214.68.120.1 to 4.68.127.2544.68.127.2552,046
1454.68.128.0/214.68.128.1 to 4.68.135.2544.68.135.2552,046
1464.68.136.0/214.68.136.1 to 4.68.143.2544.68.143.2552,046
1474.68.144.0/214.68.144.1 to 4.68.151.2544.68.151.2552,046
1484.68.152.0/214.68.152.1 to 4.68.159.2544.68.159.2552,046
1494.68.160.0/214.68.160.1 to 4.68.167.2544.68.167.2552,046
1504.68.168.0/214.68.168.1 to 4.68.175.2544.68.175.2552,046
1514.68.176.0/214.68.176.1 to 4.68.183.2544.68.183.2552,046
1524.68.184.0/214.68.184.1 to 4.68.191.2544.68.191.2552,046
1534.68.192.0/214.68.192.1 to 4.68.199.2544.68.199.2552,046
1544.68.200.0/214.68.200.1 to 4.68.207.2544.68.207.2552,046
1554.68.208.0/214.68.208.1 to 4.68.215.2544.68.215.2552,046
1564.68.216.0/214.68.216.1 to 4.68.223.2544.68.223.2552,046
1574.68.224.0/214.68.224.1 to 4.68.231.2544.68.231.2552,046
1584.68.232.0/214.68.232.1 to 4.68.239.2544.68.239.2552,046
1594.68.240.0/214.68.240.1 to 4.68.247.2544.68.247.2552,046
1604.68.248.0/214.68.248.1 to 4.68.255.2544.68.255.2552,046
1614.69.0.0/214.69.0.1 to 4.69.7.2544.69.7.2552,046
1624.69.8.0/214.69.8.1 to 4.69.15.2544.69.15.2552,046
1634.69.16.0/214.69.16.1 to 4.69.23.2544.69.23.2552,046
1644.69.24.0/214.69.24.1 to 4.69.31.2544.69.31.2552,046
1654.69.32.0/214.69.32.1 to 4.69.39.2544.69.39.2552,046
1664.69.40.0/214.69.40.1 to 4.69.47.2544.69.47.2552,046
1674.69.48.0/214.69.48.1 to 4.69.55.2544.69.55.2552,046
1684.69.56.0/214.69.56.1 to 4.69.63.2544.69.63.2552,046
1694.69.64.0/214.69.64.1 to 4.69.71.2544.69.71.2552,046
1704.69.72.0/214.69.72.1 to 4.69.79.2544.69.79.2552,046
1714.69.80.0/214.69.80.1 to 4.69.87.2544.69.87.2552,046
1724.69.88.0/214.69.88.1 to 4.69.95.2544.69.95.2552,046
1734.69.96.0/214.69.96.1 to 4.69.103.2544.69.103.2552,046
1744.69.104.0/214.69.104.1 to 4.69.111.2544.69.111.2552,046
1754.69.112.0/214.69.112.1 to 4.69.119.2544.69.119.2552,046
1764.69.120.0/214.69.120.1 to 4.69.127.2544.69.127.2552,046
1774.69.128.0/214.69.128.1 to 4.69.135.2544.69.135.2552,046
1784.69.136.0/214.69.136.1 to 4.69.143.2544.69.143.2552,046
1794.69.144.0/214.69.144.1 to 4.69.151.2544.69.151.2552,046
1804.69.152.0/214.69.152.1 to 4.69.159.2544.69.159.2552,046
1814.69.160.0/214.69.160.1 to 4.69.167.2544.69.167.2552,046
1824.69.168.0/214.69.168.1 to 4.69.175.2544.69.175.2552,046
1834.69.176.0/214.69.176.1 to 4.69.183.2544.69.183.2552,046
1844.69.184.0/214.69.184.1 to 4.69.191.2544.69.191.2552,046
1854.69.192.0/214.69.192.1 to 4.69.199.2544.69.199.2552,046
1864.69.200.0/214.69.200.1 to 4.69.207.2544.69.207.2552,046
1874.69.208.0/214.69.208.1 to 4.69.215.2544.69.215.2552,046
1884.69.216.0/214.69.216.1 to 4.69.223.2544.69.223.2552,046
1894.69.224.0/214.69.224.1 to 4.69.231.2544.69.231.2552,046
1904.69.232.0/214.69.232.1 to 4.69.239.2544.69.239.2552,046
1914.69.240.0/214.69.240.1 to 4.69.247.2544.69.247.2552,046
1924.69.248.0/214.69.248.1 to 4.69.255.2544.69.255.2552,046
1934.70.0.0/214.70.0.1 to 4.70.7.2544.70.7.2552,046
1944.70.8.0/214.70.8.1 to 4.70.15.2544.70.15.2552,046
1954.70.16.0/214.70.16.1 to 4.70.23.2544.70.23.2552,046
1964.70.24.0/214.70.24.1 to 4.70.31.2544.70.31.2552,046
1974.70.32.0/214.70.32.1 to 4.70.39.2544.70.39.2552,046
1984.70.40.0/214.70.40.1 to 4.70.47.2544.70.47.2552,046
1994.70.48.0/214.70.48.1 to 4.70.55.2544.70.55.2552,046
2004.70.56.0/214.70.56.1 to 4.70.63.2544.70.63.2552,046
2014.70.64.0/214.70.64.1 to 4.70.71.2544.70.71.2552,046
2024.70.72.0/214.70.72.1 to 4.70.79.2544.70.79.2552,046
2034.70.80.0/214.70.80.1 to 4.70.87.2544.70.87.2552,046
2044.70.88.0/214.70.88.1 to 4.70.95.2544.70.95.2552,046
2054.70.96.0/214.70.96.1 to 4.70.103.2544.70.103.2552,046
2064.70.104.0/214.70.104.1 to 4.70.111.2544.70.111.2552,046
2074.70.112.0/214.70.112.1 to 4.70.119.2544.70.119.2552,046
2084.70.120.0/214.70.120.1 to 4.70.127.2544.70.127.2552,046
2094.70.128.0/214.70.128.1 to 4.70.135.2544.70.135.2552,046
2104.70.136.0/214.70.136.1 to 4.70.143.2544.70.143.2552,046
2114.70.144.0/214.70.144.1 to 4.70.151.2544.70.151.2552,046
2124.70.152.0/214.70.152.1 to 4.70.159.2544.70.159.2552,046
2134.70.160.0/214.70.160.1 to 4.70.167.2544.70.167.2552,046
2144.70.168.0/214.70.168.1 to 4.70.175.2544.70.175.2552,046
2154.70.176.0/214.70.176.1 to 4.70.183.2544.70.183.2552,046
2164.70.184.0/214.70.184.1 to 4.70.191.2544.70.191.2552,046
2174.70.192.0/214.70.192.1 to 4.70.199.2544.70.199.2552,046
2184.70.200.0/214.70.200.1 to 4.70.207.2544.70.207.2552,046
2194.70.208.0/214.70.208.1 to 4.70.215.2544.70.215.2552,046
2204.70.216.0/214.70.216.1 to 4.70.223.2544.70.223.2552,046
2214.70.224.0/214.70.224.1 to 4.70.231.2544.70.231.2552,046
2224.70.232.0/214.70.232.1 to 4.70.239.2544.70.239.2552,046
2234.70.240.0/214.70.240.1 to 4.70.247.2544.70.247.2552,046
2244.70.248.0/214.70.248.1 to 4.70.255.2544.70.255.2552,046
2254.71.0.0/214.71.0.1 to 4.71.7.2544.71.7.2552,046
2264.71.8.0/214.71.8.1 to 4.71.15.2544.71.15.2552,046
2274.71.16.0/214.71.16.1 to 4.71.23.2544.71.23.2552,046
2284.71.24.0/214.71.24.1 to 4.71.31.2544.71.31.2552,046
2294.71.32.0/214.71.32.1 to 4.71.39.2544.71.39.2552,046
2304.71.40.0/214.71.40.1 to 4.71.47.2544.71.47.2552,046
2314.71.48.0/214.71.48.1 to 4.71.55.2544.71.55.2552,046
2324.71.56.0/214.71.56.1 to 4.71.63.2544.71.63.2552,046
2334.71.64.0/214.71.64.1 to 4.71.71.2544.71.71.2552,046
2344.71.72.0/214.71.72.1 to 4.71.79.2544.71.79.2552,046
2354.71.80.0/214.71.80.1 to 4.71.87.2544.71.87.2552,046
2364.71.88.0/214.71.88.1 to 4.71.95.2544.71.95.2552,046
2374.71.96.0/214.71.96.1 to 4.71.103.2544.71.103.2552,046
2384.71.104.0/214.71.104.1 to 4.71.111.2544.71.111.2552,046
2394.71.112.0/214.71.112.1 to 4.71.119.2544.71.119.2552,046
2404.71.120.0/214.71.120.1 to 4.71.127.2544.71.127.2552,046
2414.71.128.0/214.71.128.1 to 4.71.135.2544.71.135.2552,046
2424.71.136.0/214.71.136.1 to 4.71.143.2544.71.143.2552,046
2434.71.144.0/214.71.144.1 to 4.71.151.2544.71.151.2552,046
2444.71.152.0/214.71.152.1 to 4.71.159.2544.71.159.2552,046
2454.71.160.0/214.71.160.1 to 4.71.167.2544.71.167.2552,046
2464.71.168.0/214.71.168.1 to 4.71.175.2544.71.175.2552,046
2474.71.176.0/214.71.176.1 to 4.71.183.2544.71.183.2552,046
2484.71.184.0/214.71.184.1 to 4.71.191.2544.71.191.2552,046
2494.71.192.0/214.71.192.1 to 4.71.199.2544.71.199.2552,046
2504.71.200.0/214.71.200.1 to 4.71.207.2544.71.207.2552,046
2514.71.208.0/214.71.208.1 to 4.71.215.2544.71.215.2552,046
2524.71.216.0/214.71.216.1 to 4.71.223.2544.71.223.2552,046
2534.71.224.0/214.71.224.1 to 4.71.231.2544.71.231.2552,046
2544.71.232.0/214.71.232.1 to 4.71.239.2544.71.239.2552,046
2554.71.240.0/214.71.240.1 to 4.71.247.2544.71.247.2552,046
2564.71.248.0/214.71.248.1 to 4.71.255.2544.71.255.2552,046

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.