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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.

Network16.0.0.0/6
Usable hosts67,108,862
Subnet mask252.0.0.0
Addresses67,108,864
Network address
16.0.0.0
Broadcast address
19.255.255.255
First usable
16.0.0.1
Last usable
19.255.255.254
Usable hosts
67,108,862 (67,108,864 less the network and broadcast addresses)
Subnet mask
252.0.0.0
Wildcard mask
3.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/6
Type
Public public
Old class
A (default /8)
As numbers
Hex 10000000 · Integer 268435456 to 335544319
Reverse DNS zones
16.in-addr.arpa
17.in-addr.arpa
18.in-addr.arpa
19.in-addr.arpa
/6 is not on a 8-bit boundary, so it takes 4 /8 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00010000.00000000.00000000.0000000016.0.0.0
Subnet mask11111100.00000000.00000000.00000000252.0.0.0
Network00010000.00000000.00000000.0000000016.0.0.0
Broadcast00010011.11111111.11111111.1111111119.255.255.255
Split into smaller subnets/13
/7 (2)/8 (4)/9 (8)/10 (16)/11 (32)/12 (64)/13 (128)/14 (256)/15 (512)/16 (1,024)/17 (2,048)/18 (4,096)

16.0.0.0/6 makes 128 subnets of /13.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
116.0.0.0/1316.0.0.1 to 16.7.255.25416.7.255.255524,286
216.8.0.0/1316.8.0.1 to 16.15.255.25416.15.255.255524,286
316.16.0.0/1316.16.0.1 to 16.23.255.25416.23.255.255524,286
416.24.0.0/1316.24.0.1 to 16.31.255.25416.31.255.255524,286
516.32.0.0/1316.32.0.1 to 16.39.255.25416.39.255.255524,286
616.40.0.0/1316.40.0.1 to 16.47.255.25416.47.255.255524,286
716.48.0.0/1316.48.0.1 to 16.55.255.25416.55.255.255524,286
816.56.0.0/1316.56.0.1 to 16.63.255.25416.63.255.255524,286
916.64.0.0/1316.64.0.1 to 16.71.255.25416.71.255.255524,286
1016.72.0.0/1316.72.0.1 to 16.79.255.25416.79.255.255524,286
1116.80.0.0/1316.80.0.1 to 16.87.255.25416.87.255.255524,286
1216.88.0.0/1316.88.0.1 to 16.95.255.25416.95.255.255524,286
1316.96.0.0/1316.96.0.1 to 16.103.255.25416.103.255.255524,286
1416.104.0.0/1316.104.0.1 to 16.111.255.25416.111.255.255524,286
1516.112.0.0/1316.112.0.1 to 16.119.255.25416.119.255.255524,286
1616.120.0.0/1316.120.0.1 to 16.127.255.25416.127.255.255524,286
1716.128.0.0/1316.128.0.1 to 16.135.255.25416.135.255.255524,286
1816.136.0.0/1316.136.0.1 to 16.143.255.25416.143.255.255524,286
1916.144.0.0/1316.144.0.1 to 16.151.255.25416.151.255.255524,286
2016.152.0.0/1316.152.0.1 to 16.159.255.25416.159.255.255524,286
2116.160.0.0/1316.160.0.1 to 16.167.255.25416.167.255.255524,286
2216.168.0.0/1316.168.0.1 to 16.175.255.25416.175.255.255524,286
2316.176.0.0/1316.176.0.1 to 16.183.255.25416.183.255.255524,286
2416.184.0.0/1316.184.0.1 to 16.191.255.25416.191.255.255524,286
2516.192.0.0/1316.192.0.1 to 16.199.255.25416.199.255.255524,286
2616.200.0.0/1316.200.0.1 to 16.207.255.25416.207.255.255524,286
2716.208.0.0/1316.208.0.1 to 16.215.255.25416.215.255.255524,286
2816.216.0.0/1316.216.0.1 to 16.223.255.25416.223.255.255524,286
2916.224.0.0/1316.224.0.1 to 16.231.255.25416.231.255.255524,286
3016.232.0.0/1316.232.0.1 to 16.239.255.25416.239.255.255524,286
3116.240.0.0/1316.240.0.1 to 16.247.255.25416.247.255.255524,286
3216.248.0.0/1316.248.0.1 to 16.255.255.25416.255.255.255524,286
3317.0.0.0/1317.0.0.1 to 17.7.255.25417.7.255.255524,286
3417.8.0.0/1317.8.0.1 to 17.15.255.25417.15.255.255524,286
3517.16.0.0/1317.16.0.1 to 17.23.255.25417.23.255.255524,286
3617.24.0.0/1317.24.0.1 to 17.31.255.25417.31.255.255524,286
3717.32.0.0/1317.32.0.1 to 17.39.255.25417.39.255.255524,286
3817.40.0.0/1317.40.0.1 to 17.47.255.25417.47.255.255524,286
3917.48.0.0/1317.48.0.1 to 17.55.255.25417.55.255.255524,286
4017.56.0.0/1317.56.0.1 to 17.63.255.25417.63.255.255524,286
4117.64.0.0/1317.64.0.1 to 17.71.255.25417.71.255.255524,286
4217.72.0.0/1317.72.0.1 to 17.79.255.25417.79.255.255524,286
4317.80.0.0/1317.80.0.1 to 17.87.255.25417.87.255.255524,286
4417.88.0.0/1317.88.0.1 to 17.95.255.25417.95.255.255524,286
4517.96.0.0/1317.96.0.1 to 17.103.255.25417.103.255.255524,286
4617.104.0.0/1317.104.0.1 to 17.111.255.25417.111.255.255524,286
4717.112.0.0/1317.112.0.1 to 17.119.255.25417.119.255.255524,286
4817.120.0.0/1317.120.0.1 to 17.127.255.25417.127.255.255524,286
4917.128.0.0/1317.128.0.1 to 17.135.255.25417.135.255.255524,286
5017.136.0.0/1317.136.0.1 to 17.143.255.25417.143.255.255524,286
5117.144.0.0/1317.144.0.1 to 17.151.255.25417.151.255.255524,286
5217.152.0.0/1317.152.0.1 to 17.159.255.25417.159.255.255524,286
5317.160.0.0/1317.160.0.1 to 17.167.255.25417.167.255.255524,286
5417.168.0.0/1317.168.0.1 to 17.175.255.25417.175.255.255524,286
5517.176.0.0/1317.176.0.1 to 17.183.255.25417.183.255.255524,286
5617.184.0.0/1317.184.0.1 to 17.191.255.25417.191.255.255524,286
5717.192.0.0/1317.192.0.1 to 17.199.255.25417.199.255.255524,286
5817.200.0.0/1317.200.0.1 to 17.207.255.25417.207.255.255524,286
5917.208.0.0/1317.208.0.1 to 17.215.255.25417.215.255.255524,286
6017.216.0.0/1317.216.0.1 to 17.223.255.25417.223.255.255524,286
6117.224.0.0/1317.224.0.1 to 17.231.255.25417.231.255.255524,286
6217.232.0.0/1317.232.0.1 to 17.239.255.25417.239.255.255524,286
6317.240.0.0/1317.240.0.1 to 17.247.255.25417.247.255.255524,286
6417.248.0.0/1317.248.0.1 to 17.255.255.25417.255.255.255524,286
6518.0.0.0/1318.0.0.1 to 18.7.255.25418.7.255.255524,286
6618.8.0.0/1318.8.0.1 to 18.15.255.25418.15.255.255524,286
6718.16.0.0/1318.16.0.1 to 18.23.255.25418.23.255.255524,286
6818.24.0.0/1318.24.0.1 to 18.31.255.25418.31.255.255524,286
6918.32.0.0/1318.32.0.1 to 18.39.255.25418.39.255.255524,286
7018.40.0.0/1318.40.0.1 to 18.47.255.25418.47.255.255524,286
7118.48.0.0/1318.48.0.1 to 18.55.255.25418.55.255.255524,286
7218.56.0.0/1318.56.0.1 to 18.63.255.25418.63.255.255524,286
7318.64.0.0/1318.64.0.1 to 18.71.255.25418.71.255.255524,286
7418.72.0.0/1318.72.0.1 to 18.79.255.25418.79.255.255524,286
7518.80.0.0/1318.80.0.1 to 18.87.255.25418.87.255.255524,286
7618.88.0.0/1318.88.0.1 to 18.95.255.25418.95.255.255524,286
7718.96.0.0/1318.96.0.1 to 18.103.255.25418.103.255.255524,286
7818.104.0.0/1318.104.0.1 to 18.111.255.25418.111.255.255524,286
7918.112.0.0/1318.112.0.1 to 18.119.255.25418.119.255.255524,286
8018.120.0.0/1318.120.0.1 to 18.127.255.25418.127.255.255524,286
8118.128.0.0/1318.128.0.1 to 18.135.255.25418.135.255.255524,286
8218.136.0.0/1318.136.0.1 to 18.143.255.25418.143.255.255524,286
8318.144.0.0/1318.144.0.1 to 18.151.255.25418.151.255.255524,286
8418.152.0.0/1318.152.0.1 to 18.159.255.25418.159.255.255524,286
8518.160.0.0/1318.160.0.1 to 18.167.255.25418.167.255.255524,286
8618.168.0.0/1318.168.0.1 to 18.175.255.25418.175.255.255524,286
8718.176.0.0/1318.176.0.1 to 18.183.255.25418.183.255.255524,286
8818.184.0.0/1318.184.0.1 to 18.191.255.25418.191.255.255524,286
8918.192.0.0/1318.192.0.1 to 18.199.255.25418.199.255.255524,286
9018.200.0.0/1318.200.0.1 to 18.207.255.25418.207.255.255524,286
9118.208.0.0/1318.208.0.1 to 18.215.255.25418.215.255.255524,286
9218.216.0.0/1318.216.0.1 to 18.223.255.25418.223.255.255524,286
9318.224.0.0/1318.224.0.1 to 18.231.255.25418.231.255.255524,286
9418.232.0.0/1318.232.0.1 to 18.239.255.25418.239.255.255524,286
9518.240.0.0/1318.240.0.1 to 18.247.255.25418.247.255.255524,286
9618.248.0.0/1318.248.0.1 to 18.255.255.25418.255.255.255524,286
9719.0.0.0/1319.0.0.1 to 19.7.255.25419.7.255.255524,286
9819.8.0.0/1319.8.0.1 to 19.15.255.25419.15.255.255524,286
9919.16.0.0/1319.16.0.1 to 19.23.255.25419.23.255.255524,286
10019.24.0.0/1319.24.0.1 to 19.31.255.25419.31.255.255524,286
10119.32.0.0/1319.32.0.1 to 19.39.255.25419.39.255.255524,286
10219.40.0.0/1319.40.0.1 to 19.47.255.25419.47.255.255524,286
10319.48.0.0/1319.48.0.1 to 19.55.255.25419.55.255.255524,286
10419.56.0.0/1319.56.0.1 to 19.63.255.25419.63.255.255524,286
10519.64.0.0/1319.64.0.1 to 19.71.255.25419.71.255.255524,286
10619.72.0.0/1319.72.0.1 to 19.79.255.25419.79.255.255524,286
10719.80.0.0/1319.80.0.1 to 19.87.255.25419.87.255.255524,286
10819.88.0.0/1319.88.0.1 to 19.95.255.25419.95.255.255524,286
10919.96.0.0/1319.96.0.1 to 19.103.255.25419.103.255.255524,286
11019.104.0.0/1319.104.0.1 to 19.111.255.25419.111.255.255524,286
11119.112.0.0/1319.112.0.1 to 19.119.255.25419.119.255.255524,286
11219.120.0.0/1319.120.0.1 to 19.127.255.25419.127.255.255524,286
11319.128.0.0/1319.128.0.1 to 19.135.255.25419.135.255.255524,286
11419.136.0.0/1319.136.0.1 to 19.143.255.25419.143.255.255524,286
11519.144.0.0/1319.144.0.1 to 19.151.255.25419.151.255.255524,286
11619.152.0.0/1319.152.0.1 to 19.159.255.25419.159.255.255524,286
11719.160.0.0/1319.160.0.1 to 19.167.255.25419.167.255.255524,286
11819.168.0.0/1319.168.0.1 to 19.175.255.25419.175.255.255524,286
11919.176.0.0/1319.176.0.1 to 19.183.255.25419.183.255.255524,286
12019.184.0.0/1319.184.0.1 to 19.191.255.25419.191.255.255524,286
12119.192.0.0/1319.192.0.1 to 19.199.255.25419.199.255.255524,286
12219.200.0.0/1319.200.0.1 to 19.207.255.25419.207.255.255524,286
12319.208.0.0/1319.208.0.1 to 19.215.255.25419.215.255.255524,286
12419.216.0.0/1319.216.0.1 to 19.223.255.25419.223.255.255524,286
12519.224.0.0/1319.224.0.1 to 19.231.255.25419.231.255.255524,286
12619.232.0.0/1319.232.0.1 to 19.239.255.25419.239.255.255524,286
12719.240.0.0/1319.240.0.1 to 19.247.255.25419.247.255.255524,286
12819.248.0.0/1319.248.0.1 to 19.255.255.25419.255.255.255524,286

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.