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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/7
Addresses2^121
/64 networks2^57
Network
2a00::/7
First address
2a00::
Last address
2bff:ffff:ffff:ffff:ffff:ffff:ffff:ffff
Addresses
2,658,455,991,569,831,745,807,614,120,560,689,152 (2^121)
/64 networks (LANs)
144,115,188,075,855,872 (2^57)
Full form
2a00:0000:0000:0000:0000:0000:0000:0000
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zones
a.2.ip6.arpa
b.2.ip6.arpa
/7 is not on a 4-bit boundary, so it takes 2 /8 zones.
Split into smaller subnets/20
/8 (2)/9 (4)/10 (8)/11 (16)/12 (32)/16 (512)/20 (8,192)

2a00::/7 makes 8,192 subnets of /20; the first 256 are listed.

Subnets
#SubnetLast address
12a00::/202a00:fff:ffff:ffff:ffff:ffff:ffff:ffff
22a00:1000::/202a00:1fff:ffff:ffff:ffff:ffff:ffff:ffff
32a00:2000::/202a00:2fff:ffff:ffff:ffff:ffff:ffff:ffff
42a00:3000::/202a00:3fff:ffff:ffff:ffff:ffff:ffff:ffff
52a00:4000::/202a00:4fff:ffff:ffff:ffff:ffff:ffff:ffff
62a00:5000::/202a00:5fff:ffff:ffff:ffff:ffff:ffff:ffff
72a00:6000::/202a00:6fff:ffff:ffff:ffff:ffff:ffff:ffff
82a00:7000::/202a00:7fff:ffff:ffff:ffff:ffff:ffff:ffff
92a00:8000::/202a00:8fff:ffff:ffff:ffff:ffff:ffff:ffff
102a00:9000::/202a00:9fff:ffff:ffff:ffff:ffff:ffff:ffff
112a00:a000::/202a00:afff:ffff:ffff:ffff:ffff:ffff:ffff
122a00:b000::/202a00:bfff:ffff:ffff:ffff:ffff:ffff:ffff
132a00:c000::/202a00:cfff:ffff:ffff:ffff:ffff:ffff:ffff
142a00:d000::/202a00:dfff:ffff:ffff:ffff:ffff:ffff:ffff
152a00:e000::/202a00:efff:ffff:ffff:ffff:ffff:ffff:ffff
162a00:f000::/202a00:ffff:ffff:ffff:ffff:ffff:ffff:ffff
172a01::/202a01:fff:ffff:ffff:ffff:ffff:ffff:ffff
182a01:1000::/202a01:1fff:ffff:ffff:ffff:ffff:ffff:ffff
192a01:2000::/202a01:2fff:ffff:ffff:ffff:ffff:ffff:ffff
202a01:3000::/202a01:3fff:ffff:ffff:ffff:ffff:ffff:ffff
212a01:4000::/202a01:4fff:ffff:ffff:ffff:ffff:ffff:ffff
222a01:5000::/202a01:5fff:ffff:ffff:ffff:ffff:ffff:ffff
232a01:6000::/202a01:6fff:ffff:ffff:ffff:ffff:ffff:ffff
242a01:7000::/202a01:7fff:ffff:ffff:ffff:ffff:ffff:ffff
252a01:8000::/202a01:8fff:ffff:ffff:ffff:ffff:ffff:ffff
262a01:9000::/202a01:9fff:ffff:ffff:ffff:ffff:ffff:ffff
272a01:a000::/202a01:afff:ffff:ffff:ffff:ffff:ffff:ffff
282a01:b000::/202a01:bfff:ffff:ffff:ffff:ffff:ffff:ffff
292a01:c000::/202a01:cfff:ffff:ffff:ffff:ffff:ffff:ffff
302a01:d000::/202a01:dfff:ffff:ffff:ffff:ffff:ffff:ffff
312a01:e000::/202a01:efff:ffff:ffff:ffff:ffff:ffff:ffff
322a01:f000::/202a01:ffff:ffff:ffff:ffff:ffff:ffff:ffff
332a02::/202a02:fff:ffff:ffff:ffff:ffff:ffff:ffff
342a02:1000::/202a02:1fff:ffff:ffff:ffff:ffff:ffff:ffff
352a02:2000::/202a02:2fff:ffff:ffff:ffff:ffff:ffff:ffff
362a02:3000::/202a02:3fff:ffff:ffff:ffff:ffff:ffff:ffff
372a02:4000::/202a02:4fff:ffff:ffff:ffff:ffff:ffff:ffff
382a02:5000::/202a02:5fff:ffff:ffff:ffff:ffff:ffff:ffff
392a02:6000::/202a02:6fff:ffff:ffff:ffff:ffff:ffff:ffff
402a02:7000::/202a02:7fff:ffff:ffff:ffff:ffff:ffff:ffff
412a02:8000::/202a02:8fff:ffff:ffff:ffff:ffff:ffff:ffff
422a02:9000::/202a02:9fff:ffff:ffff:ffff:ffff:ffff:ffff
432a02:a000::/202a02:afff:ffff:ffff:ffff:ffff:ffff:ffff
442a02:b000::/202a02:bfff:ffff:ffff:ffff:ffff:ffff:ffff
452a02:c000::/202a02:cfff:ffff:ffff:ffff:ffff:ffff:ffff
462a02:d000::/202a02:dfff:ffff:ffff:ffff:ffff:ffff:ffff
472a02:e000::/202a02:efff:ffff:ffff:ffff:ffff:ffff:ffff
482a02:f000::/202a02:ffff:ffff:ffff:ffff:ffff:ffff:ffff
492a03::/202a03:fff:ffff:ffff:ffff:ffff:ffff:ffff
502a03:1000::/202a03:1fff:ffff:ffff:ffff:ffff:ffff:ffff
512a03:2000::/202a03:2fff:ffff:ffff:ffff:ffff:ffff:ffff
522a03:3000::/202a03:3fff:ffff:ffff:ffff:ffff:ffff:ffff
532a03:4000::/202a03:4fff:ffff:ffff:ffff:ffff:ffff:ffff
542a03:5000::/202a03:5fff:ffff:ffff:ffff:ffff:ffff:ffff
552a03:6000::/202a03:6fff:ffff:ffff:ffff:ffff:ffff:ffff
562a03:7000::/202a03:7fff:ffff:ffff:ffff:ffff:ffff:ffff
572a03:8000::/202a03:8fff:ffff:ffff:ffff:ffff:ffff:ffff
582a03:9000::/202a03:9fff:ffff:ffff:ffff:ffff:ffff:ffff
592a03:a000::/202a03:afff:ffff:ffff:ffff:ffff:ffff:ffff
602a03:b000::/202a03:bfff:ffff:ffff:ffff:ffff:ffff:ffff
612a03:c000::/202a03:cfff:ffff:ffff:ffff:ffff:ffff:ffff
622a03:d000::/202a03:dfff:ffff:ffff:ffff:ffff:ffff:ffff
632a03:e000::/202a03:efff:ffff:ffff:ffff:ffff:ffff:ffff
642a03:f000::/202a03:ffff:ffff:ffff:ffff:ffff:ffff:ffff
652a04::/202a04:fff:ffff:ffff:ffff:ffff:ffff:ffff
662a04:1000::/202a04:1fff:ffff:ffff:ffff:ffff:ffff:ffff
672a04:2000::/202a04:2fff:ffff:ffff:ffff:ffff:ffff:ffff
682a04:3000::/202a04:3fff:ffff:ffff:ffff:ffff:ffff:ffff
692a04:4000::/202a04:4fff:ffff:ffff:ffff:ffff:ffff:ffff
702a04:5000::/202a04:5fff:ffff:ffff:ffff:ffff:ffff:ffff
712a04:6000::/202a04:6fff:ffff:ffff:ffff:ffff:ffff:ffff
722a04:7000::/202a04:7fff:ffff:ffff:ffff:ffff:ffff:ffff
732a04:8000::/202a04:8fff:ffff:ffff:ffff:ffff:ffff:ffff
742a04:9000::/202a04:9fff:ffff:ffff:ffff:ffff:ffff:ffff
752a04:a000::/202a04:afff:ffff:ffff:ffff:ffff:ffff:ffff
762a04:b000::/202a04:bfff:ffff:ffff:ffff:ffff:ffff:ffff
772a04:c000::/202a04:cfff:ffff:ffff:ffff:ffff:ffff:ffff
782a04:d000::/202a04:dfff:ffff:ffff:ffff:ffff:ffff:ffff
792a04:e000::/202a04:efff:ffff:ffff:ffff:ffff:ffff:ffff
802a04:f000::/202a04:ffff:ffff:ffff:ffff:ffff:ffff:ffff
812a05::/202a05:fff:ffff:ffff:ffff:ffff:ffff:ffff
822a05:1000::/202a05:1fff:ffff:ffff:ffff:ffff:ffff:ffff
832a05:2000::/202a05:2fff:ffff:ffff:ffff:ffff:ffff:ffff
842a05:3000::/202a05:3fff:ffff:ffff:ffff:ffff:ffff:ffff
852a05:4000::/202a05:4fff:ffff:ffff:ffff:ffff:ffff:ffff
862a05:5000::/202a05:5fff:ffff:ffff:ffff:ffff:ffff:ffff
872a05:6000::/202a05:6fff:ffff:ffff:ffff:ffff:ffff:ffff
882a05:7000::/202a05:7fff:ffff:ffff:ffff:ffff:ffff:ffff
892a05:8000::/202a05:8fff:ffff:ffff:ffff:ffff:ffff:ffff
902a05:9000::/202a05:9fff:ffff:ffff:ffff:ffff:ffff:ffff
912a05:a000::/202a05:afff:ffff:ffff:ffff:ffff:ffff:ffff
922a05:b000::/202a05:bfff:ffff:ffff:ffff:ffff:ffff:ffff
932a05:c000::/202a05:cfff:ffff:ffff:ffff:ffff:ffff:ffff
942a05:d000::/202a05:dfff:ffff:ffff:ffff:ffff:ffff:ffff
952a05:e000::/202a05:efff:ffff:ffff:ffff:ffff:ffff:ffff
962a05:f000::/202a05:ffff:ffff:ffff:ffff:ffff:ffff:ffff
972a06::/202a06:fff:ffff:ffff:ffff:ffff:ffff:ffff
982a06:1000::/202a06:1fff:ffff:ffff:ffff:ffff:ffff:ffff
992a06:2000::/202a06:2fff:ffff:ffff:ffff:ffff:ffff:ffff
1002a06:3000::/202a06:3fff:ffff:ffff:ffff:ffff:ffff:ffff
1012a06:4000::/202a06:4fff:ffff:ffff:ffff:ffff:ffff:ffff
1022a06:5000::/202a06:5fff:ffff:ffff:ffff:ffff:ffff:ffff
1032a06:6000::/202a06:6fff:ffff:ffff:ffff:ffff:ffff:ffff
1042a06:7000::/202a06:7fff:ffff:ffff:ffff:ffff:ffff:ffff
1052a06:8000::/202a06:8fff:ffff:ffff:ffff:ffff:ffff:ffff
1062a06:9000::/202a06:9fff:ffff:ffff:ffff:ffff:ffff:ffff
1072a06:a000::/202a06:afff:ffff:ffff:ffff:ffff:ffff:ffff
1082a06:b000::/202a06:bfff:ffff:ffff:ffff:ffff:ffff:ffff
1092a06:c000::/202a06:cfff:ffff:ffff:ffff:ffff:ffff:ffff
1102a06:d000::/202a06:dfff:ffff:ffff:ffff:ffff:ffff:ffff
1112a06:e000::/202a06:efff:ffff:ffff:ffff:ffff:ffff:ffff
1122a06:f000::/202a06:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1132a07::/202a07:fff:ffff:ffff:ffff:ffff:ffff:ffff
1142a07:1000::/202a07:1fff:ffff:ffff:ffff:ffff:ffff:ffff
1152a07:2000::/202a07:2fff:ffff:ffff:ffff:ffff:ffff:ffff
1162a07:3000::/202a07:3fff:ffff:ffff:ffff:ffff:ffff:ffff
1172a07:4000::/202a07:4fff:ffff:ffff:ffff:ffff:ffff:ffff
1182a07:5000::/202a07:5fff:ffff:ffff:ffff:ffff:ffff:ffff
1192a07:6000::/202a07:6fff:ffff:ffff:ffff:ffff:ffff:ffff
1202a07:7000::/202a07:7fff:ffff:ffff:ffff:ffff:ffff:ffff
1212a07:8000::/202a07:8fff:ffff:ffff:ffff:ffff:ffff:ffff
1222a07:9000::/202a07:9fff:ffff:ffff:ffff:ffff:ffff:ffff
1232a07:a000::/202a07:afff:ffff:ffff:ffff:ffff:ffff:ffff
1242a07:b000::/202a07:bfff:ffff:ffff:ffff:ffff:ffff:ffff
1252a07:c000::/202a07:cfff:ffff:ffff:ffff:ffff:ffff:ffff
1262a07:d000::/202a07:dfff:ffff:ffff:ffff:ffff:ffff:ffff
1272a07:e000::/202a07:efff:ffff:ffff:ffff:ffff:ffff:ffff
1282a07:f000::/202a07:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1292a08::/202a08:fff:ffff:ffff:ffff:ffff:ffff:ffff
1302a08:1000::/202a08:1fff:ffff:ffff:ffff:ffff:ffff:ffff
1312a08:2000::/202a08:2fff:ffff:ffff:ffff:ffff:ffff:ffff
1322a08:3000::/202a08:3fff:ffff:ffff:ffff:ffff:ffff:ffff
1332a08:4000::/202a08:4fff:ffff:ffff:ffff:ffff:ffff:ffff
1342a08:5000::/202a08:5fff:ffff:ffff:ffff:ffff:ffff:ffff
1352a08:6000::/202a08:6fff:ffff:ffff:ffff:ffff:ffff:ffff
1362a08:7000::/202a08:7fff:ffff:ffff:ffff:ffff:ffff:ffff
1372a08:8000::/202a08:8fff:ffff:ffff:ffff:ffff:ffff:ffff
1382a08:9000::/202a08:9fff:ffff:ffff:ffff:ffff:ffff:ffff
1392a08:a000::/202a08:afff:ffff:ffff:ffff:ffff:ffff:ffff
1402a08:b000::/202a08:bfff:ffff:ffff:ffff:ffff:ffff:ffff
1412a08:c000::/202a08:cfff:ffff:ffff:ffff:ffff:ffff:ffff
1422a08:d000::/202a08:dfff:ffff:ffff:ffff:ffff:ffff:ffff
1432a08:e000::/202a08:efff:ffff:ffff:ffff:ffff:ffff:ffff
1442a08:f000::/202a08:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1452a09::/202a09:fff:ffff:ffff:ffff:ffff:ffff:ffff
1462a09:1000::/202a09:1fff:ffff:ffff:ffff:ffff:ffff:ffff
1472a09:2000::/202a09:2fff:ffff:ffff:ffff:ffff:ffff:ffff
1482a09:3000::/202a09:3fff:ffff:ffff:ffff:ffff:ffff:ffff
1492a09:4000::/202a09:4fff:ffff:ffff:ffff:ffff:ffff:ffff
1502a09:5000::/202a09:5fff:ffff:ffff:ffff:ffff:ffff:ffff
1512a09:6000::/202a09:6fff:ffff:ffff:ffff:ffff:ffff:ffff
1522a09:7000::/202a09:7fff:ffff:ffff:ffff:ffff:ffff:ffff
1532a09:8000::/202a09:8fff:ffff:ffff:ffff:ffff:ffff:ffff
1542a09:9000::/202a09:9fff:ffff:ffff:ffff:ffff:ffff:ffff
1552a09:a000::/202a09:afff:ffff:ffff:ffff:ffff:ffff:ffff
1562a09:b000::/202a09:bfff:ffff:ffff:ffff:ffff:ffff:ffff
1572a09:c000::/202a09:cfff:ffff:ffff:ffff:ffff:ffff:ffff
1582a09:d000::/202a09:dfff:ffff:ffff:ffff:ffff:ffff:ffff
1592a09:e000::/202a09:efff:ffff:ffff:ffff:ffff:ffff:ffff
1602a09:f000::/202a09:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1612a0a::/202a0a:fff:ffff:ffff:ffff:ffff:ffff:ffff
1622a0a:1000::/202a0a:1fff:ffff:ffff:ffff:ffff:ffff:ffff
1632a0a:2000::/202a0a:2fff:ffff:ffff:ffff:ffff:ffff:ffff
1642a0a:3000::/202a0a:3fff:ffff:ffff:ffff:ffff:ffff:ffff
1652a0a:4000::/202a0a:4fff:ffff:ffff:ffff:ffff:ffff:ffff
1662a0a:5000::/202a0a:5fff:ffff:ffff:ffff:ffff:ffff:ffff
1672a0a:6000::/202a0a:6fff:ffff:ffff:ffff:ffff:ffff:ffff
1682a0a:7000::/202a0a:7fff:ffff:ffff:ffff:ffff:ffff:ffff
1692a0a:8000::/202a0a:8fff:ffff:ffff:ffff:ffff:ffff:ffff
1702a0a:9000::/202a0a:9fff:ffff:ffff:ffff:ffff:ffff:ffff
1712a0a:a000::/202a0a:afff:ffff:ffff:ffff:ffff:ffff:ffff
1722a0a:b000::/202a0a:bfff:ffff:ffff:ffff:ffff:ffff:ffff
1732a0a:c000::/202a0a:cfff:ffff:ffff:ffff:ffff:ffff:ffff
1742a0a:d000::/202a0a:dfff:ffff:ffff:ffff:ffff:ffff:ffff
1752a0a:e000::/202a0a:efff:ffff:ffff:ffff:ffff:ffff:ffff
1762a0a:f000::/202a0a:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1772a0b::/202a0b:fff:ffff:ffff:ffff:ffff:ffff:ffff
1782a0b:1000::/202a0b:1fff:ffff:ffff:ffff:ffff:ffff:ffff
1792a0b:2000::/202a0b:2fff:ffff:ffff:ffff:ffff:ffff:ffff
1802a0b:3000::/202a0b:3fff:ffff:ffff:ffff:ffff:ffff:ffff
1812a0b:4000::/202a0b:4fff:ffff:ffff:ffff:ffff:ffff:ffff
1822a0b:5000::/202a0b:5fff:ffff:ffff:ffff:ffff:ffff:ffff
1832a0b:6000::/202a0b:6fff:ffff:ffff:ffff:ffff:ffff:ffff
1842a0b:7000::/202a0b:7fff:ffff:ffff:ffff:ffff:ffff:ffff
1852a0b:8000::/202a0b:8fff:ffff:ffff:ffff:ffff:ffff:ffff
1862a0b:9000::/202a0b:9fff:ffff:ffff:ffff:ffff:ffff:ffff
1872a0b:a000::/202a0b:afff:ffff:ffff:ffff:ffff:ffff:ffff
1882a0b:b000::/202a0b:bfff:ffff:ffff:ffff:ffff:ffff:ffff
1892a0b:c000::/202a0b:cfff:ffff:ffff:ffff:ffff:ffff:ffff
1902a0b:d000::/202a0b:dfff:ffff:ffff:ffff:ffff:ffff:ffff
1912a0b:e000::/202a0b:efff:ffff:ffff:ffff:ffff:ffff:ffff
1922a0b:f000::/202a0b:ffff:ffff:ffff:ffff:ffff:ffff:ffff
1932a0c::/202a0c:fff:ffff:ffff:ffff:ffff:ffff:ffff
1942a0c:1000::/202a0c:1fff:ffff:ffff:ffff:ffff:ffff:ffff
1952a0c:2000::/202a0c:2fff:ffff:ffff:ffff:ffff:ffff:ffff
1962a0c:3000::/202a0c:3fff:ffff:ffff:ffff:ffff:ffff:ffff
1972a0c:4000::/202a0c:4fff:ffff:ffff:ffff:ffff:ffff:ffff
1982a0c:5000::/202a0c:5fff:ffff:ffff:ffff:ffff:ffff:ffff
1992a0c:6000::/202a0c:6fff:ffff:ffff:ffff:ffff:ffff:ffff
2002a0c:7000::/202a0c:7fff:ffff:ffff:ffff:ffff:ffff:ffff
2012a0c:8000::/202a0c:8fff:ffff:ffff:ffff:ffff:ffff:ffff
2022a0c:9000::/202a0c:9fff:ffff:ffff:ffff:ffff:ffff:ffff
2032a0c:a000::/202a0c:afff:ffff:ffff:ffff:ffff:ffff:ffff
2042a0c:b000::/202a0c:bfff:ffff:ffff:ffff:ffff:ffff:ffff
2052a0c:c000::/202a0c:cfff:ffff:ffff:ffff:ffff:ffff:ffff
2062a0c:d000::/202a0c:dfff:ffff:ffff:ffff:ffff:ffff:ffff
2072a0c:e000::/202a0c:efff:ffff:ffff:ffff:ffff:ffff:ffff
2082a0c:f000::/202a0c:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2092a0d::/202a0d:fff:ffff:ffff:ffff:ffff:ffff:ffff
2102a0d:1000::/202a0d:1fff:ffff:ffff:ffff:ffff:ffff:ffff
2112a0d:2000::/202a0d:2fff:ffff:ffff:ffff:ffff:ffff:ffff
2122a0d:3000::/202a0d:3fff:ffff:ffff:ffff:ffff:ffff:ffff
2132a0d:4000::/202a0d:4fff:ffff:ffff:ffff:ffff:ffff:ffff
2142a0d:5000::/202a0d:5fff:ffff:ffff:ffff:ffff:ffff:ffff
2152a0d:6000::/202a0d:6fff:ffff:ffff:ffff:ffff:ffff:ffff
2162a0d:7000::/202a0d:7fff:ffff:ffff:ffff:ffff:ffff:ffff
2172a0d:8000::/202a0d:8fff:ffff:ffff:ffff:ffff:ffff:ffff
2182a0d:9000::/202a0d:9fff:ffff:ffff:ffff:ffff:ffff:ffff
2192a0d:a000::/202a0d:afff:ffff:ffff:ffff:ffff:ffff:ffff
2202a0d:b000::/202a0d:bfff:ffff:ffff:ffff:ffff:ffff:ffff
2212a0d:c000::/202a0d:cfff:ffff:ffff:ffff:ffff:ffff:ffff
2222a0d:d000::/202a0d:dfff:ffff:ffff:ffff:ffff:ffff:ffff
2232a0d:e000::/202a0d:efff:ffff:ffff:ffff:ffff:ffff:ffff
2242a0d:f000::/202a0d:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2252a0e::/202a0e:fff:ffff:ffff:ffff:ffff:ffff:ffff
2262a0e:1000::/202a0e:1fff:ffff:ffff:ffff:ffff:ffff:ffff
2272a0e:2000::/202a0e:2fff:ffff:ffff:ffff:ffff:ffff:ffff
2282a0e:3000::/202a0e:3fff:ffff:ffff:ffff:ffff:ffff:ffff
2292a0e:4000::/202a0e:4fff:ffff:ffff:ffff:ffff:ffff:ffff
2302a0e:5000::/202a0e:5fff:ffff:ffff:ffff:ffff:ffff:ffff
2312a0e:6000::/202a0e:6fff:ffff:ffff:ffff:ffff:ffff:ffff
2322a0e:7000::/202a0e:7fff:ffff:ffff:ffff:ffff:ffff:ffff
2332a0e:8000::/202a0e:8fff:ffff:ffff:ffff:ffff:ffff:ffff
2342a0e:9000::/202a0e:9fff:ffff:ffff:ffff:ffff:ffff:ffff
2352a0e:a000::/202a0e:afff:ffff:ffff:ffff:ffff:ffff:ffff
2362a0e:b000::/202a0e:bfff:ffff:ffff:ffff:ffff:ffff:ffff
2372a0e:c000::/202a0e:cfff:ffff:ffff:ffff:ffff:ffff:ffff
2382a0e:d000::/202a0e:dfff:ffff:ffff:ffff:ffff:ffff:ffff
2392a0e:e000::/202a0e:efff:ffff:ffff:ffff:ffff:ffff:ffff
2402a0e:f000::/202a0e:ffff:ffff:ffff:ffff:ffff:ffff:ffff
2412a0f::/202a0f:fff:ffff:ffff:ffff:ffff:ffff:ffff
2422a0f:1000::/202a0f:1fff:ffff:ffff:ffff:ffff:ffff:ffff
2432a0f:2000::/202a0f:2fff:ffff:ffff:ffff:ffff:ffff:ffff
2442a0f:3000::/202a0f:3fff:ffff:ffff:ffff:ffff:ffff:ffff
2452a0f:4000::/202a0f:4fff:ffff:ffff:ffff:ffff:ffff:ffff
2462a0f:5000::/202a0f:5fff:ffff:ffff:ffff:ffff:ffff:ffff
2472a0f:6000::/202a0f:6fff:ffff:ffff:ffff:ffff:ffff:ffff
2482a0f:7000::/202a0f:7fff:ffff:ffff:ffff:ffff:ffff:ffff
2492a0f:8000::/202a0f:8fff:ffff:ffff:ffff:ffff:ffff:ffff
2502a0f:9000::/202a0f:9fff:ffff:ffff:ffff:ffff:ffff:ffff
2512a0f:a000::/202a0f:afff:ffff:ffff:ffff:ffff:ffff:ffff
2522a0f:b000::/202a0f:bfff:ffff:ffff:ffff:ffff:ffff:ffff
2532a0f:c000::/202a0f:cfff:ffff:ffff:ffff:ffff:ffff:ffff
2542a0f:d000::/202a0f:dfff:ffff:ffff:ffff:ffff:ffff:ffff
2552a0f:e000::/202a0f:efff:ffff:ffff:ffff:ffff:ffff:ffff
2562a0f:f000::/202a0f:ffff: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.