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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/120
Addresses256
/64 networksPart of one
Network
2001:db8::ec00/120
First address
2001:db8::ec00
Last address
2001:db8::ecff
Addresses
256
/64 networks (LANs)
None: smaller than one /64 LAN
Full form
2001:0db8:0000:0000:0000:0000:0000:ec00
Type
Documentation 2001:db8::/32
For examples; never used on a network
Reverse DNS zone
c.e.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa
Split into smaller subnets/128
/121 (2)/122 (4)/123 (8)/124 (16)/127 (128)/128 (256)

2001:db8::ec00/120 makes 256 subnets of /128.

Subnets
#SubnetLast address
12001:db8::ec00/1282001:db8::ec00
22001:db8::ec01/1282001:db8::ec01
32001:db8::ec02/1282001:db8::ec02
42001:db8::ec03/1282001:db8::ec03
52001:db8::ec04/1282001:db8::ec04
62001:db8::ec05/1282001:db8::ec05
72001:db8::ec06/1282001:db8::ec06
82001:db8::ec07/1282001:db8::ec07
92001:db8::ec08/1282001:db8::ec08
102001:db8::ec09/1282001:db8::ec09
112001:db8::ec0a/1282001:db8::ec0a
122001:db8::ec0b/1282001:db8::ec0b
132001:db8::ec0c/1282001:db8::ec0c
142001:db8::ec0d/1282001:db8::ec0d
152001:db8::ec0e/1282001:db8::ec0e
162001:db8::ec0f/1282001:db8::ec0f
172001:db8::ec10/1282001:db8::ec10
182001:db8::ec11/1282001:db8::ec11
192001:db8::ec12/1282001:db8::ec12
202001:db8::ec13/1282001:db8::ec13
212001:db8::ec14/1282001:db8::ec14
222001:db8::ec15/1282001:db8::ec15
232001:db8::ec16/1282001:db8::ec16
242001:db8::ec17/1282001:db8::ec17
252001:db8::ec18/1282001:db8::ec18
262001:db8::ec19/1282001:db8::ec19
272001:db8::ec1a/1282001:db8::ec1a
282001:db8::ec1b/1282001:db8::ec1b
292001:db8::ec1c/1282001:db8::ec1c
302001:db8::ec1d/1282001:db8::ec1d
312001:db8::ec1e/1282001:db8::ec1e
322001:db8::ec1f/1282001:db8::ec1f
332001:db8::ec20/1282001:db8::ec20
342001:db8::ec21/1282001:db8::ec21
352001:db8::ec22/1282001:db8::ec22
362001:db8::ec23/1282001:db8::ec23
372001:db8::ec24/1282001:db8::ec24
382001:db8::ec25/1282001:db8::ec25
392001:db8::ec26/1282001:db8::ec26
402001:db8::ec27/1282001:db8::ec27
412001:db8::ec28/1282001:db8::ec28
422001:db8::ec29/1282001:db8::ec29
432001:db8::ec2a/1282001:db8::ec2a
442001:db8::ec2b/1282001:db8::ec2b
452001:db8::ec2c/1282001:db8::ec2c
462001:db8::ec2d/1282001:db8::ec2d
472001:db8::ec2e/1282001:db8::ec2e
482001:db8::ec2f/1282001:db8::ec2f
492001:db8::ec30/1282001:db8::ec30
502001:db8::ec31/1282001:db8::ec31
512001:db8::ec32/1282001:db8::ec32
522001:db8::ec33/1282001:db8::ec33
532001:db8::ec34/1282001:db8::ec34
542001:db8::ec35/1282001:db8::ec35
552001:db8::ec36/1282001:db8::ec36
562001:db8::ec37/1282001:db8::ec37
572001:db8::ec38/1282001:db8::ec38
582001:db8::ec39/1282001:db8::ec39
592001:db8::ec3a/1282001:db8::ec3a
602001:db8::ec3b/1282001:db8::ec3b
612001:db8::ec3c/1282001:db8::ec3c
622001:db8::ec3d/1282001:db8::ec3d
632001:db8::ec3e/1282001:db8::ec3e
642001:db8::ec3f/1282001:db8::ec3f
652001:db8::ec40/1282001:db8::ec40
662001:db8::ec41/1282001:db8::ec41
672001:db8::ec42/1282001:db8::ec42
682001:db8::ec43/1282001:db8::ec43
692001:db8::ec44/1282001:db8::ec44
702001:db8::ec45/1282001:db8::ec45
712001:db8::ec46/1282001:db8::ec46
722001:db8::ec47/1282001:db8::ec47
732001:db8::ec48/1282001:db8::ec48
742001:db8::ec49/1282001:db8::ec49
752001:db8::ec4a/1282001:db8::ec4a
762001:db8::ec4b/1282001:db8::ec4b
772001:db8::ec4c/1282001:db8::ec4c
782001:db8::ec4d/1282001:db8::ec4d
792001:db8::ec4e/1282001:db8::ec4e
802001:db8::ec4f/1282001:db8::ec4f
812001:db8::ec50/1282001:db8::ec50
822001:db8::ec51/1282001:db8::ec51
832001:db8::ec52/1282001:db8::ec52
842001:db8::ec53/1282001:db8::ec53
852001:db8::ec54/1282001:db8::ec54
862001:db8::ec55/1282001:db8::ec55
872001:db8::ec56/1282001:db8::ec56
882001:db8::ec57/1282001:db8::ec57
892001:db8::ec58/1282001:db8::ec58
902001:db8::ec59/1282001:db8::ec59
912001:db8::ec5a/1282001:db8::ec5a
922001:db8::ec5b/1282001:db8::ec5b
932001:db8::ec5c/1282001:db8::ec5c
942001:db8::ec5d/1282001:db8::ec5d
952001:db8::ec5e/1282001:db8::ec5e
962001:db8::ec5f/1282001:db8::ec5f
972001:db8::ec60/1282001:db8::ec60
982001:db8::ec61/1282001:db8::ec61
992001:db8::ec62/1282001:db8::ec62
1002001:db8::ec63/1282001:db8::ec63
1012001:db8::ec64/1282001:db8::ec64
1022001:db8::ec65/1282001:db8::ec65
1032001:db8::ec66/1282001:db8::ec66
1042001:db8::ec67/1282001:db8::ec67
1052001:db8::ec68/1282001:db8::ec68
1062001:db8::ec69/1282001:db8::ec69
1072001:db8::ec6a/1282001:db8::ec6a
1082001:db8::ec6b/1282001:db8::ec6b
1092001:db8::ec6c/1282001:db8::ec6c
1102001:db8::ec6d/1282001:db8::ec6d
1112001:db8::ec6e/1282001:db8::ec6e
1122001:db8::ec6f/1282001:db8::ec6f
1132001:db8::ec70/1282001:db8::ec70
1142001:db8::ec71/1282001:db8::ec71
1152001:db8::ec72/1282001:db8::ec72
1162001:db8::ec73/1282001:db8::ec73
1172001:db8::ec74/1282001:db8::ec74
1182001:db8::ec75/1282001:db8::ec75
1192001:db8::ec76/1282001:db8::ec76
1202001:db8::ec77/1282001:db8::ec77
1212001:db8::ec78/1282001:db8::ec78
1222001:db8::ec79/1282001:db8::ec79
1232001:db8::ec7a/1282001:db8::ec7a
1242001:db8::ec7b/1282001:db8::ec7b
1252001:db8::ec7c/1282001:db8::ec7c
1262001:db8::ec7d/1282001:db8::ec7d
1272001:db8::ec7e/1282001:db8::ec7e
1282001:db8::ec7f/1282001:db8::ec7f
1292001:db8::ec80/1282001:db8::ec80
1302001:db8::ec81/1282001:db8::ec81
1312001:db8::ec82/1282001:db8::ec82
1322001:db8::ec83/1282001:db8::ec83
1332001:db8::ec84/1282001:db8::ec84
1342001:db8::ec85/1282001:db8::ec85
1352001:db8::ec86/1282001:db8::ec86
1362001:db8::ec87/1282001:db8::ec87
1372001:db8::ec88/1282001:db8::ec88
1382001:db8::ec89/1282001:db8::ec89
1392001:db8::ec8a/1282001:db8::ec8a
1402001:db8::ec8b/1282001:db8::ec8b
1412001:db8::ec8c/1282001:db8::ec8c
1422001:db8::ec8d/1282001:db8::ec8d
1432001:db8::ec8e/1282001:db8::ec8e
1442001:db8::ec8f/1282001:db8::ec8f
1452001:db8::ec90/1282001:db8::ec90
1462001:db8::ec91/1282001:db8::ec91
1472001:db8::ec92/1282001:db8::ec92
1482001:db8::ec93/1282001:db8::ec93
1492001:db8::ec94/1282001:db8::ec94
1502001:db8::ec95/1282001:db8::ec95
1512001:db8::ec96/1282001:db8::ec96
1522001:db8::ec97/1282001:db8::ec97
1532001:db8::ec98/1282001:db8::ec98
1542001:db8::ec99/1282001:db8::ec99
1552001:db8::ec9a/1282001:db8::ec9a
1562001:db8::ec9b/1282001:db8::ec9b
1572001:db8::ec9c/1282001:db8::ec9c
1582001:db8::ec9d/1282001:db8::ec9d
1592001:db8::ec9e/1282001:db8::ec9e
1602001:db8::ec9f/1282001:db8::ec9f
1612001:db8::eca0/1282001:db8::eca0
1622001:db8::eca1/1282001:db8::eca1
1632001:db8::eca2/1282001:db8::eca2
1642001:db8::eca3/1282001:db8::eca3
1652001:db8::eca4/1282001:db8::eca4
1662001:db8::eca5/1282001:db8::eca5
1672001:db8::eca6/1282001:db8::eca6
1682001:db8::eca7/1282001:db8::eca7
1692001:db8::eca8/1282001:db8::eca8
1702001:db8::eca9/1282001:db8::eca9
1712001:db8::ecaa/1282001:db8::ecaa
1722001:db8::ecab/1282001:db8::ecab
1732001:db8::ecac/1282001:db8::ecac
1742001:db8::ecad/1282001:db8::ecad
1752001:db8::ecae/1282001:db8::ecae
1762001:db8::ecaf/1282001:db8::ecaf
1772001:db8::ecb0/1282001:db8::ecb0
1782001:db8::ecb1/1282001:db8::ecb1
1792001:db8::ecb2/1282001:db8::ecb2
1802001:db8::ecb3/1282001:db8::ecb3
1812001:db8::ecb4/1282001:db8::ecb4
1822001:db8::ecb5/1282001:db8::ecb5
1832001:db8::ecb6/1282001:db8::ecb6
1842001:db8::ecb7/1282001:db8::ecb7
1852001:db8::ecb8/1282001:db8::ecb8
1862001:db8::ecb9/1282001:db8::ecb9
1872001:db8::ecba/1282001:db8::ecba
1882001:db8::ecbb/1282001:db8::ecbb
1892001:db8::ecbc/1282001:db8::ecbc
1902001:db8::ecbd/1282001:db8::ecbd
1912001:db8::ecbe/1282001:db8::ecbe
1922001:db8::ecbf/1282001:db8::ecbf
1932001:db8::ecc0/1282001:db8::ecc0
1942001:db8::ecc1/1282001:db8::ecc1
1952001:db8::ecc2/1282001:db8::ecc2
1962001:db8::ecc3/1282001:db8::ecc3
1972001:db8::ecc4/1282001:db8::ecc4
1982001:db8::ecc5/1282001:db8::ecc5
1992001:db8::ecc6/1282001:db8::ecc6
2002001:db8::ecc7/1282001:db8::ecc7
2012001:db8::ecc8/1282001:db8::ecc8
2022001:db8::ecc9/1282001:db8::ecc9
2032001:db8::ecca/1282001:db8::ecca
2042001:db8::eccb/1282001:db8::eccb
2052001:db8::eccc/1282001:db8::eccc
2062001:db8::eccd/1282001:db8::eccd
2072001:db8::ecce/1282001:db8::ecce
2082001:db8::eccf/1282001:db8::eccf
2092001:db8::ecd0/1282001:db8::ecd0
2102001:db8::ecd1/1282001:db8::ecd1
2112001:db8::ecd2/1282001:db8::ecd2
2122001:db8::ecd3/1282001:db8::ecd3
2132001:db8::ecd4/1282001:db8::ecd4
2142001:db8::ecd5/1282001:db8::ecd5
2152001:db8::ecd6/1282001:db8::ecd6
2162001:db8::ecd7/1282001:db8::ecd7
2172001:db8::ecd8/1282001:db8::ecd8
2182001:db8::ecd9/1282001:db8::ecd9
2192001:db8::ecda/1282001:db8::ecda
2202001:db8::ecdb/1282001:db8::ecdb
2212001:db8::ecdc/1282001:db8::ecdc
2222001:db8::ecdd/1282001:db8::ecdd
2232001:db8::ecde/1282001:db8::ecde
2242001:db8::ecdf/1282001:db8::ecdf
2252001:db8::ece0/1282001:db8::ece0
2262001:db8::ece1/1282001:db8::ece1
2272001:db8::ece2/1282001:db8::ece2
2282001:db8::ece3/1282001:db8::ece3
2292001:db8::ece4/1282001:db8::ece4
2302001:db8::ece5/1282001:db8::ece5
2312001:db8::ece6/1282001:db8::ece6
2322001:db8::ece7/1282001:db8::ece7
2332001:db8::ece8/1282001:db8::ece8
2342001:db8::ece9/1282001:db8::ece9
2352001:db8::ecea/1282001:db8::ecea
2362001:db8::eceb/1282001:db8::eceb
2372001:db8::ecec/1282001:db8::ecec
2382001:db8::eced/1282001:db8::eced
2392001:db8::ecee/1282001:db8::ecee
2402001:db8::ecef/1282001:db8::ecef
2412001:db8::ecf0/1282001:db8::ecf0
2422001:db8::ecf1/1282001:db8::ecf1
2432001:db8::ecf2/1282001:db8::ecf2
2442001:db8::ecf3/1282001:db8::ecf3
2452001:db8::ecf4/1282001:db8::ecf4
2462001:db8::ecf5/1282001:db8::ecf5
2472001:db8::ecf6/1282001:db8::ecf6
2482001:db8::ecf7/1282001:db8::ecf7
2492001:db8::ecf8/1282001:db8::ecf8
2502001:db8::ecf9/1282001:db8::ecf9
2512001:db8::ecfa/1282001:db8::ecfa
2522001:db8::ecfb/1282001:db8::ecfb
2532001:db8::ecfc/1282001:db8::ecfc
2542001:db8::ecfd/1282001:db8::ecfd
2552001:db8::ecfe/1282001:db8::ecfe
2562001:db8::ecff/1282001:db8::ecff

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.