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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::c200/120
First address
2001:db8::c200
Last address
2001:db8::c2ff
Addresses
256
/64 networks (LANs)
None: smaller than one /64 LAN
Full form
2001:0db8:0000:0000:0000:0000:0000:c200
Type
Documentation 2001:db8::/32
For examples; never used on a network
Reverse DNS zone
2.c.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::c200/120 makes 256 subnets of /128.

Subnets
#SubnetLast address
12001:db8::c200/1282001:db8::c200
22001:db8::c201/1282001:db8::c201
32001:db8::c202/1282001:db8::c202
42001:db8::c203/1282001:db8::c203
52001:db8::c204/1282001:db8::c204
62001:db8::c205/1282001:db8::c205
72001:db8::c206/1282001:db8::c206
82001:db8::c207/1282001:db8::c207
92001:db8::c208/1282001:db8::c208
102001:db8::c209/1282001:db8::c209
112001:db8::c20a/1282001:db8::c20a
122001:db8::c20b/1282001:db8::c20b
132001:db8::c20c/1282001:db8::c20c
142001:db8::c20d/1282001:db8::c20d
152001:db8::c20e/1282001:db8::c20e
162001:db8::c20f/1282001:db8::c20f
172001:db8::c210/1282001:db8::c210
182001:db8::c211/1282001:db8::c211
192001:db8::c212/1282001:db8::c212
202001:db8::c213/1282001:db8::c213
212001:db8::c214/1282001:db8::c214
222001:db8::c215/1282001:db8::c215
232001:db8::c216/1282001:db8::c216
242001:db8::c217/1282001:db8::c217
252001:db8::c218/1282001:db8::c218
262001:db8::c219/1282001:db8::c219
272001:db8::c21a/1282001:db8::c21a
282001:db8::c21b/1282001:db8::c21b
292001:db8::c21c/1282001:db8::c21c
302001:db8::c21d/1282001:db8::c21d
312001:db8::c21e/1282001:db8::c21e
322001:db8::c21f/1282001:db8::c21f
332001:db8::c220/1282001:db8::c220
342001:db8::c221/1282001:db8::c221
352001:db8::c222/1282001:db8::c222
362001:db8::c223/1282001:db8::c223
372001:db8::c224/1282001:db8::c224
382001:db8::c225/1282001:db8::c225
392001:db8::c226/1282001:db8::c226
402001:db8::c227/1282001:db8::c227
412001:db8::c228/1282001:db8::c228
422001:db8::c229/1282001:db8::c229
432001:db8::c22a/1282001:db8::c22a
442001:db8::c22b/1282001:db8::c22b
452001:db8::c22c/1282001:db8::c22c
462001:db8::c22d/1282001:db8::c22d
472001:db8::c22e/1282001:db8::c22e
482001:db8::c22f/1282001:db8::c22f
492001:db8::c230/1282001:db8::c230
502001:db8::c231/1282001:db8::c231
512001:db8::c232/1282001:db8::c232
522001:db8::c233/1282001:db8::c233
532001:db8::c234/1282001:db8::c234
542001:db8::c235/1282001:db8::c235
552001:db8::c236/1282001:db8::c236
562001:db8::c237/1282001:db8::c237
572001:db8::c238/1282001:db8::c238
582001:db8::c239/1282001:db8::c239
592001:db8::c23a/1282001:db8::c23a
602001:db8::c23b/1282001:db8::c23b
612001:db8::c23c/1282001:db8::c23c
622001:db8::c23d/1282001:db8::c23d
632001:db8::c23e/1282001:db8::c23e
642001:db8::c23f/1282001:db8::c23f
652001:db8::c240/1282001:db8::c240
662001:db8::c241/1282001:db8::c241
672001:db8::c242/1282001:db8::c242
682001:db8::c243/1282001:db8::c243
692001:db8::c244/1282001:db8::c244
702001:db8::c245/1282001:db8::c245
712001:db8::c246/1282001:db8::c246
722001:db8::c247/1282001:db8::c247
732001:db8::c248/1282001:db8::c248
742001:db8::c249/1282001:db8::c249
752001:db8::c24a/1282001:db8::c24a
762001:db8::c24b/1282001:db8::c24b
772001:db8::c24c/1282001:db8::c24c
782001:db8::c24d/1282001:db8::c24d
792001:db8::c24e/1282001:db8::c24e
802001:db8::c24f/1282001:db8::c24f
812001:db8::c250/1282001:db8::c250
822001:db8::c251/1282001:db8::c251
832001:db8::c252/1282001:db8::c252
842001:db8::c253/1282001:db8::c253
852001:db8::c254/1282001:db8::c254
862001:db8::c255/1282001:db8::c255
872001:db8::c256/1282001:db8::c256
882001:db8::c257/1282001:db8::c257
892001:db8::c258/1282001:db8::c258
902001:db8::c259/1282001:db8::c259
912001:db8::c25a/1282001:db8::c25a
922001:db8::c25b/1282001:db8::c25b
932001:db8::c25c/1282001:db8::c25c
942001:db8::c25d/1282001:db8::c25d
952001:db8::c25e/1282001:db8::c25e
962001:db8::c25f/1282001:db8::c25f
972001:db8::c260/1282001:db8::c260
982001:db8::c261/1282001:db8::c261
992001:db8::c262/1282001:db8::c262
1002001:db8::c263/1282001:db8::c263
1012001:db8::c264/1282001:db8::c264
1022001:db8::c265/1282001:db8::c265
1032001:db8::c266/1282001:db8::c266
1042001:db8::c267/1282001:db8::c267
1052001:db8::c268/1282001:db8::c268
1062001:db8::c269/1282001:db8::c269
1072001:db8::c26a/1282001:db8::c26a
1082001:db8::c26b/1282001:db8::c26b
1092001:db8::c26c/1282001:db8::c26c
1102001:db8::c26d/1282001:db8::c26d
1112001:db8::c26e/1282001:db8::c26e
1122001:db8::c26f/1282001:db8::c26f
1132001:db8::c270/1282001:db8::c270
1142001:db8::c271/1282001:db8::c271
1152001:db8::c272/1282001:db8::c272
1162001:db8::c273/1282001:db8::c273
1172001:db8::c274/1282001:db8::c274
1182001:db8::c275/1282001:db8::c275
1192001:db8::c276/1282001:db8::c276
1202001:db8::c277/1282001:db8::c277
1212001:db8::c278/1282001:db8::c278
1222001:db8::c279/1282001:db8::c279
1232001:db8::c27a/1282001:db8::c27a
1242001:db8::c27b/1282001:db8::c27b
1252001:db8::c27c/1282001:db8::c27c
1262001:db8::c27d/1282001:db8::c27d
1272001:db8::c27e/1282001:db8::c27e
1282001:db8::c27f/1282001:db8::c27f
1292001:db8::c280/1282001:db8::c280
1302001:db8::c281/1282001:db8::c281
1312001:db8::c282/1282001:db8::c282
1322001:db8::c283/1282001:db8::c283
1332001:db8::c284/1282001:db8::c284
1342001:db8::c285/1282001:db8::c285
1352001:db8::c286/1282001:db8::c286
1362001:db8::c287/1282001:db8::c287
1372001:db8::c288/1282001:db8::c288
1382001:db8::c289/1282001:db8::c289
1392001:db8::c28a/1282001:db8::c28a
1402001:db8::c28b/1282001:db8::c28b
1412001:db8::c28c/1282001:db8::c28c
1422001:db8::c28d/1282001:db8::c28d
1432001:db8::c28e/1282001:db8::c28e
1442001:db8::c28f/1282001:db8::c28f
1452001:db8::c290/1282001:db8::c290
1462001:db8::c291/1282001:db8::c291
1472001:db8::c292/1282001:db8::c292
1482001:db8::c293/1282001:db8::c293
1492001:db8::c294/1282001:db8::c294
1502001:db8::c295/1282001:db8::c295
1512001:db8::c296/1282001:db8::c296
1522001:db8::c297/1282001:db8::c297
1532001:db8::c298/1282001:db8::c298
1542001:db8::c299/1282001:db8::c299
1552001:db8::c29a/1282001:db8::c29a
1562001:db8::c29b/1282001:db8::c29b
1572001:db8::c29c/1282001:db8::c29c
1582001:db8::c29d/1282001:db8::c29d
1592001:db8::c29e/1282001:db8::c29e
1602001:db8::c29f/1282001:db8::c29f
1612001:db8::c2a0/1282001:db8::c2a0
1622001:db8::c2a1/1282001:db8::c2a1
1632001:db8::c2a2/1282001:db8::c2a2
1642001:db8::c2a3/1282001:db8::c2a3
1652001:db8::c2a4/1282001:db8::c2a4
1662001:db8::c2a5/1282001:db8::c2a5
1672001:db8::c2a6/1282001:db8::c2a6
1682001:db8::c2a7/1282001:db8::c2a7
1692001:db8::c2a8/1282001:db8::c2a8
1702001:db8::c2a9/1282001:db8::c2a9
1712001:db8::c2aa/1282001:db8::c2aa
1722001:db8::c2ab/1282001:db8::c2ab
1732001:db8::c2ac/1282001:db8::c2ac
1742001:db8::c2ad/1282001:db8::c2ad
1752001:db8::c2ae/1282001:db8::c2ae
1762001:db8::c2af/1282001:db8::c2af
1772001:db8::c2b0/1282001:db8::c2b0
1782001:db8::c2b1/1282001:db8::c2b1
1792001:db8::c2b2/1282001:db8::c2b2
1802001:db8::c2b3/1282001:db8::c2b3
1812001:db8::c2b4/1282001:db8::c2b4
1822001:db8::c2b5/1282001:db8::c2b5
1832001:db8::c2b6/1282001:db8::c2b6
1842001:db8::c2b7/1282001:db8::c2b7
1852001:db8::c2b8/1282001:db8::c2b8
1862001:db8::c2b9/1282001:db8::c2b9
1872001:db8::c2ba/1282001:db8::c2ba
1882001:db8::c2bb/1282001:db8::c2bb
1892001:db8::c2bc/1282001:db8::c2bc
1902001:db8::c2bd/1282001:db8::c2bd
1912001:db8::c2be/1282001:db8::c2be
1922001:db8::c2bf/1282001:db8::c2bf
1932001:db8::c2c0/1282001:db8::c2c0
1942001:db8::c2c1/1282001:db8::c2c1
1952001:db8::c2c2/1282001:db8::c2c2
1962001:db8::c2c3/1282001:db8::c2c3
1972001:db8::c2c4/1282001:db8::c2c4
1982001:db8::c2c5/1282001:db8::c2c5
1992001:db8::c2c6/1282001:db8::c2c6
2002001:db8::c2c7/1282001:db8::c2c7
2012001:db8::c2c8/1282001:db8::c2c8
2022001:db8::c2c9/1282001:db8::c2c9
2032001:db8::c2ca/1282001:db8::c2ca
2042001:db8::c2cb/1282001:db8::c2cb
2052001:db8::c2cc/1282001:db8::c2cc
2062001:db8::c2cd/1282001:db8::c2cd
2072001:db8::c2ce/1282001:db8::c2ce
2082001:db8::c2cf/1282001:db8::c2cf
2092001:db8::c2d0/1282001:db8::c2d0
2102001:db8::c2d1/1282001:db8::c2d1
2112001:db8::c2d2/1282001:db8::c2d2
2122001:db8::c2d3/1282001:db8::c2d3
2132001:db8::c2d4/1282001:db8::c2d4
2142001:db8::c2d5/1282001:db8::c2d5
2152001:db8::c2d6/1282001:db8::c2d6
2162001:db8::c2d7/1282001:db8::c2d7
2172001:db8::c2d8/1282001:db8::c2d8
2182001:db8::c2d9/1282001:db8::c2d9
2192001:db8::c2da/1282001:db8::c2da
2202001:db8::c2db/1282001:db8::c2db
2212001:db8::c2dc/1282001:db8::c2dc
2222001:db8::c2dd/1282001:db8::c2dd
2232001:db8::c2de/1282001:db8::c2de
2242001:db8::c2df/1282001:db8::c2df
2252001:db8::c2e0/1282001:db8::c2e0
2262001:db8::c2e1/1282001:db8::c2e1
2272001:db8::c2e2/1282001:db8::c2e2
2282001:db8::c2e3/1282001:db8::c2e3
2292001:db8::c2e4/1282001:db8::c2e4
2302001:db8::c2e5/1282001:db8::c2e5
2312001:db8::c2e6/1282001:db8::c2e6
2322001:db8::c2e7/1282001:db8::c2e7
2332001:db8::c2e8/1282001:db8::c2e8
2342001:db8::c2e9/1282001:db8::c2e9
2352001:db8::c2ea/1282001:db8::c2ea
2362001:db8::c2eb/1282001:db8::c2eb
2372001:db8::c2ec/1282001:db8::c2ec
2382001:db8::c2ed/1282001:db8::c2ed
2392001:db8::c2ee/1282001:db8::c2ee
2402001:db8::c2ef/1282001:db8::c2ef
2412001:db8::c2f0/1282001:db8::c2f0
2422001:db8::c2f1/1282001:db8::c2f1
2432001:db8::c2f2/1282001:db8::c2f2
2442001:db8::c2f3/1282001:db8::c2f3
2452001:db8::c2f4/1282001:db8::c2f4
2462001:db8::c2f5/1282001:db8::c2f5
2472001:db8::c2f6/1282001:db8::c2f6
2482001:db8::c2f7/1282001:db8::c2f7
2492001:db8::c2f8/1282001:db8::c2f8
2502001:db8::c2f9/1282001:db8::c2f9
2512001:db8::c2fa/1282001:db8::c2fa
2522001:db8::c2fb/1282001:db8::c2fb
2532001:db8::c2fc/1282001:db8::c2fc
2542001:db8::c2fd/1282001:db8::c2fd
2552001:db8::c2fe/1282001:db8::c2fe
2562001:db8::c2ff/1282001:db8::c2ff

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.