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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.

Network36.0.0.0/6
Usable hosts67,108,862
Subnet mask252.0.0.0
Addresses67,108,864
Network address
36.0.0.0
Broadcast address
39.255.255.255
First usable
36.0.0.1
Last usable
39.255.255.254
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 24000000 · Integer 603979776 to 671088639
Reverse DNS zones
36.in-addr.arpa
37.in-addr.arpa
38.in-addr.arpa
39.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
Address00100100.00000000.00000000.0000000036.0.0.0
Subnet mask11111100.00000000.00000000.00000000252.0.0.0
Network00100100.00000000.00000000.0000000036.0.0.0
Broadcast00100111.11111111.11111111.1111111139.255.255.255
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)

36.0.0.0/6 makes 128 subnets of /13.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
136.0.0.0/1336.0.0.1 to 36.7.255.25436.7.255.255524,286
236.8.0.0/1336.8.0.1 to 36.15.255.25436.15.255.255524,286
336.16.0.0/1336.16.0.1 to 36.23.255.25436.23.255.255524,286
436.24.0.0/1336.24.0.1 to 36.31.255.25436.31.255.255524,286
536.32.0.0/1336.32.0.1 to 36.39.255.25436.39.255.255524,286
636.40.0.0/1336.40.0.1 to 36.47.255.25436.47.255.255524,286
736.48.0.0/1336.48.0.1 to 36.55.255.25436.55.255.255524,286
836.56.0.0/1336.56.0.1 to 36.63.255.25436.63.255.255524,286
936.64.0.0/1336.64.0.1 to 36.71.255.25436.71.255.255524,286
1036.72.0.0/1336.72.0.1 to 36.79.255.25436.79.255.255524,286
1136.80.0.0/1336.80.0.1 to 36.87.255.25436.87.255.255524,286
1236.88.0.0/1336.88.0.1 to 36.95.255.25436.95.255.255524,286
1336.96.0.0/1336.96.0.1 to 36.103.255.25436.103.255.255524,286
1436.104.0.0/1336.104.0.1 to 36.111.255.25436.111.255.255524,286
1536.112.0.0/1336.112.0.1 to 36.119.255.25436.119.255.255524,286
1636.120.0.0/1336.120.0.1 to 36.127.255.25436.127.255.255524,286
1736.128.0.0/1336.128.0.1 to 36.135.255.25436.135.255.255524,286
1836.136.0.0/1336.136.0.1 to 36.143.255.25436.143.255.255524,286
1936.144.0.0/1336.144.0.1 to 36.151.255.25436.151.255.255524,286
2036.152.0.0/1336.152.0.1 to 36.159.255.25436.159.255.255524,286
2136.160.0.0/1336.160.0.1 to 36.167.255.25436.167.255.255524,286
2236.168.0.0/1336.168.0.1 to 36.175.255.25436.175.255.255524,286
2336.176.0.0/1336.176.0.1 to 36.183.255.25436.183.255.255524,286
2436.184.0.0/1336.184.0.1 to 36.191.255.25436.191.255.255524,286
2536.192.0.0/1336.192.0.1 to 36.199.255.25436.199.255.255524,286
2636.200.0.0/1336.200.0.1 to 36.207.255.25436.207.255.255524,286
2736.208.0.0/1336.208.0.1 to 36.215.255.25436.215.255.255524,286
2836.216.0.0/1336.216.0.1 to 36.223.255.25436.223.255.255524,286
2936.224.0.0/1336.224.0.1 to 36.231.255.25436.231.255.255524,286
3036.232.0.0/1336.232.0.1 to 36.239.255.25436.239.255.255524,286
3136.240.0.0/1336.240.0.1 to 36.247.255.25436.247.255.255524,286
3236.248.0.0/1336.248.0.1 to 36.255.255.25436.255.255.255524,286
3337.0.0.0/1337.0.0.1 to 37.7.255.25437.7.255.255524,286
3437.8.0.0/1337.8.0.1 to 37.15.255.25437.15.255.255524,286
3537.16.0.0/1337.16.0.1 to 37.23.255.25437.23.255.255524,286
3637.24.0.0/1337.24.0.1 to 37.31.255.25437.31.255.255524,286
3737.32.0.0/1337.32.0.1 to 37.39.255.25437.39.255.255524,286
3837.40.0.0/1337.40.0.1 to 37.47.255.25437.47.255.255524,286
3937.48.0.0/1337.48.0.1 to 37.55.255.25437.55.255.255524,286
4037.56.0.0/1337.56.0.1 to 37.63.255.25437.63.255.255524,286
4137.64.0.0/1337.64.0.1 to 37.71.255.25437.71.255.255524,286
4237.72.0.0/1337.72.0.1 to 37.79.255.25437.79.255.255524,286
4337.80.0.0/1337.80.0.1 to 37.87.255.25437.87.255.255524,286
4437.88.0.0/1337.88.0.1 to 37.95.255.25437.95.255.255524,286
4537.96.0.0/1337.96.0.1 to 37.103.255.25437.103.255.255524,286
4637.104.0.0/1337.104.0.1 to 37.111.255.25437.111.255.255524,286
4737.112.0.0/1337.112.0.1 to 37.119.255.25437.119.255.255524,286
4837.120.0.0/1337.120.0.1 to 37.127.255.25437.127.255.255524,286
4937.128.0.0/1337.128.0.1 to 37.135.255.25437.135.255.255524,286
5037.136.0.0/1337.136.0.1 to 37.143.255.25437.143.255.255524,286
5137.144.0.0/1337.144.0.1 to 37.151.255.25437.151.255.255524,286
5237.152.0.0/1337.152.0.1 to 37.159.255.25437.159.255.255524,286
5337.160.0.0/1337.160.0.1 to 37.167.255.25437.167.255.255524,286
5437.168.0.0/1337.168.0.1 to 37.175.255.25437.175.255.255524,286
5537.176.0.0/1337.176.0.1 to 37.183.255.25437.183.255.255524,286
5637.184.0.0/1337.184.0.1 to 37.191.255.25437.191.255.255524,286
5737.192.0.0/1337.192.0.1 to 37.199.255.25437.199.255.255524,286
5837.200.0.0/1337.200.0.1 to 37.207.255.25437.207.255.255524,286
5937.208.0.0/1337.208.0.1 to 37.215.255.25437.215.255.255524,286
6037.216.0.0/1337.216.0.1 to 37.223.255.25437.223.255.255524,286
6137.224.0.0/1337.224.0.1 to 37.231.255.25437.231.255.255524,286
6237.232.0.0/1337.232.0.1 to 37.239.255.25437.239.255.255524,286
6337.240.0.0/1337.240.0.1 to 37.247.255.25437.247.255.255524,286
6437.248.0.0/1337.248.0.1 to 37.255.255.25437.255.255.255524,286
6538.0.0.0/1338.0.0.1 to 38.7.255.25438.7.255.255524,286
6638.8.0.0/1338.8.0.1 to 38.15.255.25438.15.255.255524,286
6738.16.0.0/1338.16.0.1 to 38.23.255.25438.23.255.255524,286
6838.24.0.0/1338.24.0.1 to 38.31.255.25438.31.255.255524,286
6938.32.0.0/1338.32.0.1 to 38.39.255.25438.39.255.255524,286
7038.40.0.0/1338.40.0.1 to 38.47.255.25438.47.255.255524,286
7138.48.0.0/1338.48.0.1 to 38.55.255.25438.55.255.255524,286
7238.56.0.0/1338.56.0.1 to 38.63.255.25438.63.255.255524,286
7338.64.0.0/1338.64.0.1 to 38.71.255.25438.71.255.255524,286
7438.72.0.0/1338.72.0.1 to 38.79.255.25438.79.255.255524,286
7538.80.0.0/1338.80.0.1 to 38.87.255.25438.87.255.255524,286
7638.88.0.0/1338.88.0.1 to 38.95.255.25438.95.255.255524,286
7738.96.0.0/1338.96.0.1 to 38.103.255.25438.103.255.255524,286
7838.104.0.0/1338.104.0.1 to 38.111.255.25438.111.255.255524,286
7938.112.0.0/1338.112.0.1 to 38.119.255.25438.119.255.255524,286
8038.120.0.0/1338.120.0.1 to 38.127.255.25438.127.255.255524,286
8138.128.0.0/1338.128.0.1 to 38.135.255.25438.135.255.255524,286
8238.136.0.0/1338.136.0.1 to 38.143.255.25438.143.255.255524,286
8338.144.0.0/1338.144.0.1 to 38.151.255.25438.151.255.255524,286
8438.152.0.0/1338.152.0.1 to 38.159.255.25438.159.255.255524,286
8538.160.0.0/1338.160.0.1 to 38.167.255.25438.167.255.255524,286
8638.168.0.0/1338.168.0.1 to 38.175.255.25438.175.255.255524,286
8738.176.0.0/1338.176.0.1 to 38.183.255.25438.183.255.255524,286
8838.184.0.0/1338.184.0.1 to 38.191.255.25438.191.255.255524,286
8938.192.0.0/1338.192.0.1 to 38.199.255.25438.199.255.255524,286
9038.200.0.0/1338.200.0.1 to 38.207.255.25438.207.255.255524,286
9138.208.0.0/1338.208.0.1 to 38.215.255.25438.215.255.255524,286
9238.216.0.0/1338.216.0.1 to 38.223.255.25438.223.255.255524,286
9338.224.0.0/1338.224.0.1 to 38.231.255.25438.231.255.255524,286
9438.232.0.0/1338.232.0.1 to 38.239.255.25438.239.255.255524,286
9538.240.0.0/1338.240.0.1 to 38.247.255.25438.247.255.255524,286
9638.248.0.0/1338.248.0.1 to 38.255.255.25438.255.255.255524,286
9739.0.0.0/1339.0.0.1 to 39.7.255.25439.7.255.255524,286
9839.8.0.0/1339.8.0.1 to 39.15.255.25439.15.255.255524,286
9939.16.0.0/1339.16.0.1 to 39.23.255.25439.23.255.255524,286
10039.24.0.0/1339.24.0.1 to 39.31.255.25439.31.255.255524,286
10139.32.0.0/1339.32.0.1 to 39.39.255.25439.39.255.255524,286
10239.40.0.0/1339.40.0.1 to 39.47.255.25439.47.255.255524,286
10339.48.0.0/1339.48.0.1 to 39.55.255.25439.55.255.255524,286
10439.56.0.0/1339.56.0.1 to 39.63.255.25439.63.255.255524,286
10539.64.0.0/1339.64.0.1 to 39.71.255.25439.71.255.255524,286
10639.72.0.0/1339.72.0.1 to 39.79.255.25439.79.255.255524,286
10739.80.0.0/1339.80.0.1 to 39.87.255.25439.87.255.255524,286
10839.88.0.0/1339.88.0.1 to 39.95.255.25439.95.255.255524,286
10939.96.0.0/1339.96.0.1 to 39.103.255.25439.103.255.255524,286
11039.104.0.0/1339.104.0.1 to 39.111.255.25439.111.255.255524,286
11139.112.0.0/1339.112.0.1 to 39.119.255.25439.119.255.255524,286
11239.120.0.0/1339.120.0.1 to 39.127.255.25439.127.255.255524,286
11339.128.0.0/1339.128.0.1 to 39.135.255.25439.135.255.255524,286
11439.136.0.0/1339.136.0.1 to 39.143.255.25439.143.255.255524,286
11539.144.0.0/1339.144.0.1 to 39.151.255.25439.151.255.255524,286
11639.152.0.0/1339.152.0.1 to 39.159.255.25439.159.255.255524,286
11739.160.0.0/1339.160.0.1 to 39.167.255.25439.167.255.255524,286
11839.168.0.0/1339.168.0.1 to 39.175.255.25439.175.255.255524,286
11939.176.0.0/1339.176.0.1 to 39.183.255.25439.183.255.255524,286
12039.184.0.0/1339.184.0.1 to 39.191.255.25439.191.255.255524,286
12139.192.0.0/1339.192.0.1 to 39.199.255.25439.199.255.255524,286
12239.200.0.0/1339.200.0.1 to 39.207.255.25439.207.255.255524,286
12339.208.0.0/1339.208.0.1 to 39.215.255.25439.215.255.255524,286
12439.216.0.0/1339.216.0.1 to 39.223.255.25439.223.255.255524,286
12539.224.0.0/1339.224.0.1 to 39.231.255.25439.231.255.255524,286
12639.232.0.0/1339.232.0.1 to 39.239.255.25439.239.255.255524,286
12739.240.0.0/1339.240.0.1 to 39.247.255.25439.247.255.255524,286
12839.248.0.0/1339.248.0.1 to 39.255.255.25439.255.255.255524,286

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.