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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.

Prefix/16
Addresses2^112
/64 networks2^48
Network
2cfa::/16
First address
2cfa::
Last address
2cfa:ffff:ffff:ffff:ffff:ffff:ffff:ffff
Addresses
5,192,296,858,534,827,628,530,496,329,220,096 (2^112)
/64 networks (LANs)
281,474,976,710,656 (2^48)
Full form
2cfa:0000:0000:0000:0000:0000:0000:0000
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zone
a.f.c.2.ip6.arpa
Split into smaller subnets/32
/17 (2)/18 (4)/19 (8)/20 (16)/24 (256)/28 (4,096)/32 (65,536)

2cfa::/16 makes 65,536 subnets of /32; the first 256 are listed.

Subnets
#SubnetLast address
12cfa::/322cfa:0:ffff:ffff:ffff:ffff:ffff:ffff
22cfa:1::/322cfa:1:ffff:ffff:ffff:ffff:ffff:ffff
32cfa:2::/322cfa:2:ffff:ffff:ffff:ffff:ffff:ffff
42cfa:3::/322cfa:3:ffff:ffff:ffff:ffff:ffff:ffff
52cfa:4::/322cfa:4:ffff:ffff:ffff:ffff:ffff:ffff
62cfa:5::/322cfa:5:ffff:ffff:ffff:ffff:ffff:ffff
72cfa:6::/322cfa:6:ffff:ffff:ffff:ffff:ffff:ffff
82cfa:7::/322cfa:7:ffff:ffff:ffff:ffff:ffff:ffff
92cfa:8::/322cfa:8:ffff:ffff:ffff:ffff:ffff:ffff
102cfa:9::/322cfa:9:ffff:ffff:ffff:ffff:ffff:ffff
112cfa:a::/322cfa:a:ffff:ffff:ffff:ffff:ffff:ffff
122cfa:b::/322cfa:b:ffff:ffff:ffff:ffff:ffff:ffff
132cfa:c::/322cfa:c:ffff:ffff:ffff:ffff:ffff:ffff
142cfa:d::/322cfa:d:ffff:ffff:ffff:ffff:ffff:ffff
152cfa:e::/322cfa:e:ffff:ffff:ffff:ffff:ffff:ffff
162cfa:f::/322cfa:f:ffff:ffff:ffff:ffff:ffff:ffff
172cfa:10::/322cfa:10:ffff:ffff:ffff:ffff:ffff:ffff
182cfa:11::/322cfa:11:ffff:ffff:ffff:ffff:ffff:ffff
192cfa:12::/322cfa:12:ffff:ffff:ffff:ffff:ffff:ffff
202cfa:13::/322cfa:13:ffff:ffff:ffff:ffff:ffff:ffff
212cfa:14::/322cfa:14:ffff:ffff:ffff:ffff:ffff:ffff
222cfa:15::/322cfa:15:ffff:ffff:ffff:ffff:ffff:ffff
232cfa:16::/322cfa:16:ffff:ffff:ffff:ffff:ffff:ffff
242cfa:17::/322cfa:17:ffff:ffff:ffff:ffff:ffff:ffff
252cfa:18::/322cfa:18:ffff:ffff:ffff:ffff:ffff:ffff
262cfa:19::/322cfa:19:ffff:ffff:ffff:ffff:ffff:ffff
272cfa:1a::/322cfa:1a:ffff:ffff:ffff:ffff:ffff:ffff
282cfa:1b::/322cfa:1b:ffff:ffff:ffff:ffff:ffff:ffff
292cfa:1c::/322cfa:1c:ffff:ffff:ffff:ffff:ffff:ffff
302cfa:1d::/322cfa:1d:ffff:ffff:ffff:ffff:ffff:ffff
312cfa:1e::/322cfa:1e:ffff:ffff:ffff:ffff:ffff:ffff
322cfa:1f::/322cfa:1f:ffff:ffff:ffff:ffff:ffff:ffff
332cfa:20::/322cfa:20:ffff:ffff:ffff:ffff:ffff:ffff
342cfa:21::/322cfa:21:ffff:ffff:ffff:ffff:ffff:ffff
352cfa:22::/322cfa:22:ffff:ffff:ffff:ffff:ffff:ffff
362cfa:23::/322cfa:23:ffff:ffff:ffff:ffff:ffff:ffff
372cfa:24::/322cfa:24:ffff:ffff:ffff:ffff:ffff:ffff
382cfa:25::/322cfa:25:ffff:ffff:ffff:ffff:ffff:ffff
392cfa:26::/322cfa:26:ffff:ffff:ffff:ffff:ffff:ffff
402cfa:27::/322cfa:27:ffff:ffff:ffff:ffff:ffff:ffff
412cfa:28::/322cfa:28:ffff:ffff:ffff:ffff:ffff:ffff
422cfa:29::/322cfa:29:ffff:ffff:ffff:ffff:ffff:ffff
432cfa:2a::/322cfa:2a:ffff:ffff:ffff:ffff:ffff:ffff
442cfa:2b::/322cfa:2b:ffff:ffff:ffff:ffff:ffff:ffff
452cfa:2c::/322cfa:2c:ffff:ffff:ffff:ffff:ffff:ffff
462cfa:2d::/322cfa:2d:ffff:ffff:ffff:ffff:ffff:ffff
472cfa:2e::/322cfa:2e:ffff:ffff:ffff:ffff:ffff:ffff
482cfa:2f::/322cfa:2f:ffff:ffff:ffff:ffff:ffff:ffff
492cfa:30::/322cfa:30:ffff:ffff:ffff:ffff:ffff:ffff
502cfa:31::/322cfa:31:ffff:ffff:ffff:ffff:ffff:ffff
512cfa:32::/322cfa:32:ffff:ffff:ffff:ffff:ffff:ffff
522cfa:33::/322cfa:33:ffff:ffff:ffff:ffff:ffff:ffff
532cfa:34::/322cfa:34:ffff:ffff:ffff:ffff:ffff:ffff
542cfa:35::/322cfa:35:ffff:ffff:ffff:ffff:ffff:ffff
552cfa:36::/322cfa:36:ffff:ffff:ffff:ffff:ffff:ffff
562cfa:37::/322cfa:37:ffff:ffff:ffff:ffff:ffff:ffff
572cfa:38::/322cfa:38:ffff:ffff:ffff:ffff:ffff:ffff
582cfa:39::/322cfa:39:ffff:ffff:ffff:ffff:ffff:ffff
592cfa:3a::/322cfa:3a:ffff:ffff:ffff:ffff:ffff:ffff
602cfa:3b::/322cfa:3b:ffff:ffff:ffff:ffff:ffff:ffff
612cfa:3c::/322cfa:3c:ffff:ffff:ffff:ffff:ffff:ffff
622cfa:3d::/322cfa:3d:ffff:ffff:ffff:ffff:ffff:ffff
632cfa:3e::/322cfa:3e:ffff:ffff:ffff:ffff:ffff:ffff
642cfa:3f::/322cfa:3f:ffff:ffff:ffff:ffff:ffff:ffff
652cfa:40::/322cfa:40:ffff:ffff:ffff:ffff:ffff:ffff
662cfa:41::/322cfa:41:ffff:ffff:ffff:ffff:ffff:ffff
672cfa:42::/322cfa:42:ffff:ffff:ffff:ffff:ffff:ffff
682cfa:43::/322cfa:43:ffff:ffff:ffff:ffff:ffff:ffff
692cfa:44::/322cfa:44:ffff:ffff:ffff:ffff:ffff:ffff
702cfa:45::/322cfa:45:ffff:ffff:ffff:ffff:ffff:ffff
712cfa:46::/322cfa:46:ffff:ffff:ffff:ffff:ffff:ffff
722cfa:47::/322cfa:47:ffff:ffff:ffff:ffff:ffff:ffff
732cfa:48::/322cfa:48:ffff:ffff:ffff:ffff:ffff:ffff
742cfa:49::/322cfa:49:ffff:ffff:ffff:ffff:ffff:ffff
752cfa:4a::/322cfa:4a:ffff:ffff:ffff:ffff:ffff:ffff
762cfa:4b::/322cfa:4b:ffff:ffff:ffff:ffff:ffff:ffff
772cfa:4c::/322cfa:4c:ffff:ffff:ffff:ffff:ffff:ffff
782cfa:4d::/322cfa:4d:ffff:ffff:ffff:ffff:ffff:ffff
792cfa:4e::/322cfa:4e:ffff:ffff:ffff:ffff:ffff:ffff
802cfa:4f::/322cfa:4f:ffff:ffff:ffff:ffff:ffff:ffff
812cfa:50::/322cfa:50:ffff:ffff:ffff:ffff:ffff:ffff
822cfa:51::/322cfa:51:ffff:ffff:ffff:ffff:ffff:ffff
832cfa:52::/322cfa:52:ffff:ffff:ffff:ffff:ffff:ffff
842cfa:53::/322cfa:53:ffff:ffff:ffff:ffff:ffff:ffff
852cfa:54::/322cfa:54:ffff:ffff:ffff:ffff:ffff:ffff
862cfa:55::/322cfa:55:ffff:ffff:ffff:ffff:ffff:ffff
872cfa:56::/322cfa:56:ffff:ffff:ffff:ffff:ffff:ffff
882cfa:57::/322cfa:57:ffff:ffff:ffff:ffff:ffff:ffff
892cfa:58::/322cfa:58:ffff:ffff:ffff:ffff:ffff:ffff
902cfa:59::/322cfa:59:ffff:ffff:ffff:ffff:ffff:ffff
912cfa:5a::/322cfa:5a:ffff:ffff:ffff:ffff:ffff:ffff
922cfa:5b::/322cfa:5b:ffff:ffff:ffff:ffff:ffff:ffff
932cfa:5c::/322cfa:5c:ffff:ffff:ffff:ffff:ffff:ffff
942cfa:5d::/322cfa:5d:ffff:ffff:ffff:ffff:ffff:ffff
952cfa:5e::/322cfa:5e:ffff:ffff:ffff:ffff:ffff:ffff
962cfa:5f::/322cfa:5f:ffff:ffff:ffff:ffff:ffff:ffff
972cfa:60::/322cfa:60:ffff:ffff:ffff:ffff:ffff:ffff
982cfa:61::/322cfa:61:ffff:ffff:ffff:ffff:ffff:ffff
992cfa:62::/322cfa:62:ffff:ffff:ffff:ffff:ffff:ffff
1002cfa:63::/322cfa:63:ffff:ffff:ffff:ffff:ffff:ffff
1012cfa:64::/322cfa:64:ffff:ffff:ffff:ffff:ffff:ffff
1022cfa:65::/322cfa:65:ffff:ffff:ffff:ffff:ffff:ffff
1032cfa:66::/322cfa:66:ffff:ffff:ffff:ffff:ffff:ffff
1042cfa:67::/322cfa:67:ffff:ffff:ffff:ffff:ffff:ffff
1052cfa:68::/322cfa:68:ffff:ffff:ffff:ffff:ffff:ffff
1062cfa:69::/322cfa:69:ffff:ffff:ffff:ffff:ffff:ffff
1072cfa:6a::/322cfa:6a:ffff:ffff:ffff:ffff:ffff:ffff
1082cfa:6b::/322cfa:6b:ffff:ffff:ffff:ffff:ffff:ffff
1092cfa:6c::/322cfa:6c:ffff:ffff:ffff:ffff:ffff:ffff
1102cfa:6d::/322cfa:6d:ffff:ffff:ffff:ffff:ffff:ffff
1112cfa:6e::/322cfa:6e:ffff:ffff:ffff:ffff:ffff:ffff
1122cfa:6f::/322cfa:6f:ffff:ffff:ffff:ffff:ffff:ffff
1132cfa:70::/322cfa:70:ffff:ffff:ffff:ffff:ffff:ffff
1142cfa:71::/322cfa:71:ffff:ffff:ffff:ffff:ffff:ffff
1152cfa:72::/322cfa:72:ffff:ffff:ffff:ffff:ffff:ffff
1162cfa:73::/322cfa:73:ffff:ffff:ffff:ffff:ffff:ffff
1172cfa:74::/322cfa:74:ffff:ffff:ffff:ffff:ffff:ffff
1182cfa:75::/322cfa:75:ffff:ffff:ffff:ffff:ffff:ffff
1192cfa:76::/322cfa:76:ffff:ffff:ffff:ffff:ffff:ffff
1202cfa:77::/322cfa:77:ffff:ffff:ffff:ffff:ffff:ffff
1212cfa:78::/322cfa:78:ffff:ffff:ffff:ffff:ffff:ffff
1222cfa:79::/322cfa:79:ffff:ffff:ffff:ffff:ffff:ffff
1232cfa:7a::/322cfa:7a:ffff:ffff:ffff:ffff:ffff:ffff
1242cfa:7b::/322cfa:7b:ffff:ffff:ffff:ffff:ffff:ffff
1252cfa:7c::/322cfa:7c:ffff:ffff:ffff:ffff:ffff:ffff
1262cfa:7d::/322cfa:7d:ffff:ffff:ffff:ffff:ffff:ffff
1272cfa:7e::/322cfa:7e:ffff:ffff:ffff:ffff:ffff:ffff
1282cfa:7f::/322cfa:7f:ffff:ffff:ffff:ffff:ffff:ffff
1292cfa:80::/322cfa:80:ffff:ffff:ffff:ffff:ffff:ffff
1302cfa:81::/322cfa:81:ffff:ffff:ffff:ffff:ffff:ffff
1312cfa:82::/322cfa:82:ffff:ffff:ffff:ffff:ffff:ffff
1322cfa:83::/322cfa:83:ffff:ffff:ffff:ffff:ffff:ffff
1332cfa:84::/322cfa:84:ffff:ffff:ffff:ffff:ffff:ffff
1342cfa:85::/322cfa:85:ffff:ffff:ffff:ffff:ffff:ffff
1352cfa:86::/322cfa:86:ffff:ffff:ffff:ffff:ffff:ffff
1362cfa:87::/322cfa:87:ffff:ffff:ffff:ffff:ffff:ffff
1372cfa:88::/322cfa:88:ffff:ffff:ffff:ffff:ffff:ffff
1382cfa:89::/322cfa:89:ffff:ffff:ffff:ffff:ffff:ffff
1392cfa:8a::/322cfa:8a:ffff:ffff:ffff:ffff:ffff:ffff
1402cfa:8b::/322cfa:8b:ffff:ffff:ffff:ffff:ffff:ffff
1412cfa:8c::/322cfa:8c:ffff:ffff:ffff:ffff:ffff:ffff
1422cfa:8d::/322cfa:8d:ffff:ffff:ffff:ffff:ffff:ffff
1432cfa:8e::/322cfa:8e:ffff:ffff:ffff:ffff:ffff:ffff
1442cfa:8f::/322cfa:8f:ffff:ffff:ffff:ffff:ffff:ffff
1452cfa:90::/322cfa:90:ffff:ffff:ffff:ffff:ffff:ffff
1462cfa:91::/322cfa:91:ffff:ffff:ffff:ffff:ffff:ffff
1472cfa:92::/322cfa:92:ffff:ffff:ffff:ffff:ffff:ffff
1482cfa:93::/322cfa:93:ffff:ffff:ffff:ffff:ffff:ffff
1492cfa:94::/322cfa:94:ffff:ffff:ffff:ffff:ffff:ffff
1502cfa:95::/322cfa:95:ffff:ffff:ffff:ffff:ffff:ffff
1512cfa:96::/322cfa:96:ffff:ffff:ffff:ffff:ffff:ffff
1522cfa:97::/322cfa:97:ffff:ffff:ffff:ffff:ffff:ffff
1532cfa:98::/322cfa:98:ffff:ffff:ffff:ffff:ffff:ffff
1542cfa:99::/322cfa:99:ffff:ffff:ffff:ffff:ffff:ffff
1552cfa:9a::/322cfa:9a:ffff:ffff:ffff:ffff:ffff:ffff
1562cfa:9b::/322cfa:9b:ffff:ffff:ffff:ffff:ffff:ffff
1572cfa:9c::/322cfa:9c:ffff:ffff:ffff:ffff:ffff:ffff
1582cfa:9d::/322cfa:9d:ffff:ffff:ffff:ffff:ffff:ffff
1592cfa:9e::/322cfa:9e:ffff:ffff:ffff:ffff:ffff:ffff
1602cfa:9f::/322cfa:9f:ffff:ffff:ffff:ffff:ffff:ffff
1612cfa:a0::/322cfa:a0:ffff:ffff:ffff:ffff:ffff:ffff
1622cfa:a1::/322cfa:a1:ffff:ffff:ffff:ffff:ffff:ffff
1632cfa:a2::/322cfa:a2:ffff:ffff:ffff:ffff:ffff:ffff
1642cfa:a3::/322cfa:a3:ffff:ffff:ffff:ffff:ffff:ffff
1652cfa:a4::/322cfa:a4:ffff:ffff:ffff:ffff:ffff:ffff
1662cfa:a5::/322cfa:a5:ffff:ffff:ffff:ffff:ffff:ffff
1672cfa:a6::/322cfa:a6:ffff:ffff:ffff:ffff:ffff:ffff
1682cfa:a7::/322cfa:a7:ffff:ffff:ffff:ffff:ffff:ffff
1692cfa:a8::/322cfa:a8:ffff:ffff:ffff:ffff:ffff:ffff
1702cfa:a9::/322cfa:a9:ffff:ffff:ffff:ffff:ffff:ffff
1712cfa:aa::/322cfa:aa:ffff:ffff:ffff:ffff:ffff:ffff
1722cfa:ab::/322cfa:ab:ffff:ffff:ffff:ffff:ffff:ffff
1732cfa:ac::/322cfa:ac:ffff:ffff:ffff:ffff:ffff:ffff
1742cfa:ad::/322cfa:ad:ffff:ffff:ffff:ffff:ffff:ffff
1752cfa:ae::/322cfa:ae:ffff:ffff:ffff:ffff:ffff:ffff
1762cfa:af::/322cfa:af:ffff:ffff:ffff:ffff:ffff:ffff
1772cfa:b0::/322cfa:b0:ffff:ffff:ffff:ffff:ffff:ffff
1782cfa:b1::/322cfa:b1:ffff:ffff:ffff:ffff:ffff:ffff
1792cfa:b2::/322cfa:b2:ffff:ffff:ffff:ffff:ffff:ffff
1802cfa:b3::/322cfa:b3:ffff:ffff:ffff:ffff:ffff:ffff
1812cfa:b4::/322cfa:b4:ffff:ffff:ffff:ffff:ffff:ffff
1822cfa:b5::/322cfa:b5:ffff:ffff:ffff:ffff:ffff:ffff
1832cfa:b6::/322cfa:b6:ffff:ffff:ffff:ffff:ffff:ffff
1842cfa:b7::/322cfa:b7:ffff:ffff:ffff:ffff:ffff:ffff
1852cfa:b8::/322cfa:b8:ffff:ffff:ffff:ffff:ffff:ffff
1862cfa:b9::/322cfa:b9:ffff:ffff:ffff:ffff:ffff:ffff
1872cfa:ba::/322cfa:ba:ffff:ffff:ffff:ffff:ffff:ffff
1882cfa:bb::/322cfa:bb:ffff:ffff:ffff:ffff:ffff:ffff
1892cfa:bc::/322cfa:bc:ffff:ffff:ffff:ffff:ffff:ffff
1902cfa:bd::/322cfa:bd:ffff:ffff:ffff:ffff:ffff:ffff
1912cfa:be::/322cfa:be:ffff:ffff:ffff:ffff:ffff:ffff
1922cfa:bf::/322cfa:bf:ffff:ffff:ffff:ffff:ffff:ffff
1932cfa:c0::/322cfa:c0:ffff:ffff:ffff:ffff:ffff:ffff
1942cfa:c1::/322cfa:c1:ffff:ffff:ffff:ffff:ffff:ffff
1952cfa:c2::/322cfa:c2:ffff:ffff:ffff:ffff:ffff:ffff
1962cfa:c3::/322cfa:c3:ffff:ffff:ffff:ffff:ffff:ffff
1972cfa:c4::/322cfa:c4:ffff:ffff:ffff:ffff:ffff:ffff
1982cfa:c5::/322cfa:c5:ffff:ffff:ffff:ffff:ffff:ffff
1992cfa:c6::/322cfa:c6:ffff:ffff:ffff:ffff:ffff:ffff
2002cfa:c7::/322cfa:c7:ffff:ffff:ffff:ffff:ffff:ffff
2012cfa:c8::/322cfa:c8:ffff:ffff:ffff:ffff:ffff:ffff
2022cfa:c9::/322cfa:c9:ffff:ffff:ffff:ffff:ffff:ffff
2032cfa:ca::/322cfa:ca:ffff:ffff:ffff:ffff:ffff:ffff
2042cfa:cb::/322cfa:cb:ffff:ffff:ffff:ffff:ffff:ffff
2052cfa:cc::/322cfa:cc:ffff:ffff:ffff:ffff:ffff:ffff
2062cfa:cd::/322cfa:cd:ffff:ffff:ffff:ffff:ffff:ffff
2072cfa:ce::/322cfa:ce:ffff:ffff:ffff:ffff:ffff:ffff
2082cfa:cf::/322cfa:cf:ffff:ffff:ffff:ffff:ffff:ffff
2092cfa:d0::/322cfa:d0:ffff:ffff:ffff:ffff:ffff:ffff
2102cfa:d1::/322cfa:d1:ffff:ffff:ffff:ffff:ffff:ffff
2112cfa:d2::/322cfa:d2:ffff:ffff:ffff:ffff:ffff:ffff
2122cfa:d3::/322cfa:d3:ffff:ffff:ffff:ffff:ffff:ffff
2132cfa:d4::/322cfa:d4:ffff:ffff:ffff:ffff:ffff:ffff
2142cfa:d5::/322cfa:d5:ffff:ffff:ffff:ffff:ffff:ffff
2152cfa:d6::/322cfa:d6:ffff:ffff:ffff:ffff:ffff:ffff
2162cfa:d7::/322cfa:d7:ffff:ffff:ffff:ffff:ffff:ffff
2172cfa:d8::/322cfa:d8:ffff:ffff:ffff:ffff:ffff:ffff
2182cfa:d9::/322cfa:d9:ffff:ffff:ffff:ffff:ffff:ffff
2192cfa:da::/322cfa:da:ffff:ffff:ffff:ffff:ffff:ffff
2202cfa:db::/322cfa:db:ffff:ffff:ffff:ffff:ffff:ffff
2212cfa:dc::/322cfa:dc:ffff:ffff:ffff:ffff:ffff:ffff
2222cfa:dd::/322cfa:dd:ffff:ffff:ffff:ffff:ffff:ffff
2232cfa:de::/322cfa:de:ffff:ffff:ffff:ffff:ffff:ffff
2242cfa:df::/322cfa:df:ffff:ffff:ffff:ffff:ffff:ffff
2252cfa:e0::/322cfa:e0:ffff:ffff:ffff:ffff:ffff:ffff
2262cfa:e1::/322cfa:e1:ffff:ffff:ffff:ffff:ffff:ffff
2272cfa:e2::/322cfa:e2:ffff:ffff:ffff:ffff:ffff:ffff
2282cfa:e3::/322cfa:e3:ffff:ffff:ffff:ffff:ffff:ffff
2292cfa:e4::/322cfa:e4:ffff:ffff:ffff:ffff:ffff:ffff
2302cfa:e5::/322cfa:e5:ffff:ffff:ffff:ffff:ffff:ffff
2312cfa:e6::/322cfa:e6:ffff:ffff:ffff:ffff:ffff:ffff
2322cfa:e7::/322cfa:e7:ffff:ffff:ffff:ffff:ffff:ffff
2332cfa:e8::/322cfa:e8:ffff:ffff:ffff:ffff:ffff:ffff
2342cfa:e9::/322cfa:e9:ffff:ffff:ffff:ffff:ffff:ffff
2352cfa:ea::/322cfa:ea:ffff:ffff:ffff:ffff:ffff:ffff
2362cfa:eb::/322cfa:eb:ffff:ffff:ffff:ffff:ffff:ffff
2372cfa:ec::/322cfa:ec:ffff:ffff:ffff:ffff:ffff:ffff
2382cfa:ed::/322cfa:ed:ffff:ffff:ffff:ffff:ffff:ffff
2392cfa:ee::/322cfa:ee:ffff:ffff:ffff:ffff:ffff:ffff
2402cfa:ef::/322cfa:ef:ffff:ffff:ffff:ffff:ffff:ffff
2412cfa:f0::/322cfa:f0:ffff:ffff:ffff:ffff:ffff:ffff
2422cfa:f1::/322cfa:f1:ffff:ffff:ffff:ffff:ffff:ffff
2432cfa:f2::/322cfa:f2:ffff:ffff:ffff:ffff:ffff:ffff
2442cfa:f3::/322cfa:f3:ffff:ffff:ffff:ffff:ffff:ffff
2452cfa:f4::/322cfa:f4:ffff:ffff:ffff:ffff:ffff:ffff
2462cfa:f5::/322cfa:f5:ffff:ffff:ffff:ffff:ffff:ffff
2472cfa:f6::/322cfa:f6:ffff:ffff:ffff:ffff:ffff:ffff
2482cfa:f7::/322cfa:f7:ffff:ffff:ffff:ffff:ffff:ffff
2492cfa:f8::/322cfa:f8:ffff:ffff:ffff:ffff:ffff:ffff
2502cfa:f9::/322cfa:f9:ffff:ffff:ffff:ffff:ffff:ffff
2512cfa:fa::/322cfa:fa:ffff:ffff:ffff:ffff:ffff:ffff
2522cfa:fb::/322cfa:fb:ffff:ffff:ffff:ffff:ffff:ffff
2532cfa:fc::/322cfa:fc:ffff:ffff:ffff:ffff:ffff:ffff
2542cfa:fd::/322cfa:fd:ffff:ffff:ffff:ffff:ffff:ffff
2552cfa:fe::/322cfa:fe:ffff:ffff:ffff:ffff:ffff:ffff
2562cfa:ff::/322cfa:ff:ffff:ffff:ffff:ffff:ffff:ffff

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.