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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.

Network36.0.0.0/7
Usable hosts33,554,430
Subnet mask254.0.0.0
Addresses33,554,432
Network address
36.0.0.0
Broadcast address
37.255.255.255
First usable
36.0.0.1
Last usable
37.255.255.254
Usable hosts
33,554,430 (33,554,432 less the network and broadcast addresses)
Subnet mask
254.0.0.0
Wildcard mask
1.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/7
Type
Public public
Old class
A (default /8)
As numbers
Hex 24000000 · Integer 603979776 to 637534207
Reverse DNS zones
36.in-addr.arpa
37.in-addr.arpa
/7 is not on a 8-bit boundary, so it takes 2 /8 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00100100.00000000.00000000.0000000036.0.0.0
Subnet mask11111110.00000000.00000000.00000000254.0.0.0
Network00100100.00000000.00000000.0000000036.0.0.0
Broadcast00100101.11111111.11111111.1111111137.255.255.255
Split into smaller subnets/14
/8 (2)/9 (4)/10 (8)/11 (16)/12 (32)/13 (64)/14 (128)/15 (256)/16 (512)/17 (1,024)/18 (2,048)/19 (4,096)

36.0.0.0/7 makes 128 subnets of /14.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
136.0.0.0/1436.0.0.1 to 36.3.255.25436.3.255.255262,142
236.4.0.0/1436.4.0.1 to 36.7.255.25436.7.255.255262,142
336.8.0.0/1436.8.0.1 to 36.11.255.25436.11.255.255262,142
436.12.0.0/1436.12.0.1 to 36.15.255.25436.15.255.255262,142
536.16.0.0/1436.16.0.1 to 36.19.255.25436.19.255.255262,142
636.20.0.0/1436.20.0.1 to 36.23.255.25436.23.255.255262,142
736.24.0.0/1436.24.0.1 to 36.27.255.25436.27.255.255262,142
836.28.0.0/1436.28.0.1 to 36.31.255.25436.31.255.255262,142
936.32.0.0/1436.32.0.1 to 36.35.255.25436.35.255.255262,142
1036.36.0.0/1436.36.0.1 to 36.39.255.25436.39.255.255262,142
1136.40.0.0/1436.40.0.1 to 36.43.255.25436.43.255.255262,142
1236.44.0.0/1436.44.0.1 to 36.47.255.25436.47.255.255262,142
1336.48.0.0/1436.48.0.1 to 36.51.255.25436.51.255.255262,142
1436.52.0.0/1436.52.0.1 to 36.55.255.25436.55.255.255262,142
1536.56.0.0/1436.56.0.1 to 36.59.255.25436.59.255.255262,142
1636.60.0.0/1436.60.0.1 to 36.63.255.25436.63.255.255262,142
1736.64.0.0/1436.64.0.1 to 36.67.255.25436.67.255.255262,142
1836.68.0.0/1436.68.0.1 to 36.71.255.25436.71.255.255262,142
1936.72.0.0/1436.72.0.1 to 36.75.255.25436.75.255.255262,142
2036.76.0.0/1436.76.0.1 to 36.79.255.25436.79.255.255262,142
2136.80.0.0/1436.80.0.1 to 36.83.255.25436.83.255.255262,142
2236.84.0.0/1436.84.0.1 to 36.87.255.25436.87.255.255262,142
2336.88.0.0/1436.88.0.1 to 36.91.255.25436.91.255.255262,142
2436.92.0.0/1436.92.0.1 to 36.95.255.25436.95.255.255262,142
2536.96.0.0/1436.96.0.1 to 36.99.255.25436.99.255.255262,142
2636.100.0.0/1436.100.0.1 to 36.103.255.25436.103.255.255262,142
2736.104.0.0/1436.104.0.1 to 36.107.255.25436.107.255.255262,142
2836.108.0.0/1436.108.0.1 to 36.111.255.25436.111.255.255262,142
2936.112.0.0/1436.112.0.1 to 36.115.255.25436.115.255.255262,142
3036.116.0.0/1436.116.0.1 to 36.119.255.25436.119.255.255262,142
3136.120.0.0/1436.120.0.1 to 36.123.255.25436.123.255.255262,142
3236.124.0.0/1436.124.0.1 to 36.127.255.25436.127.255.255262,142
3336.128.0.0/1436.128.0.1 to 36.131.255.25436.131.255.255262,142
3436.132.0.0/1436.132.0.1 to 36.135.255.25436.135.255.255262,142
3536.136.0.0/1436.136.0.1 to 36.139.255.25436.139.255.255262,142
3636.140.0.0/1436.140.0.1 to 36.143.255.25436.143.255.255262,142
3736.144.0.0/1436.144.0.1 to 36.147.255.25436.147.255.255262,142
3836.148.0.0/1436.148.0.1 to 36.151.255.25436.151.255.255262,142
3936.152.0.0/1436.152.0.1 to 36.155.255.25436.155.255.255262,142
4036.156.0.0/1436.156.0.1 to 36.159.255.25436.159.255.255262,142
4136.160.0.0/1436.160.0.1 to 36.163.255.25436.163.255.255262,142
4236.164.0.0/1436.164.0.1 to 36.167.255.25436.167.255.255262,142
4336.168.0.0/1436.168.0.1 to 36.171.255.25436.171.255.255262,142
4436.172.0.0/1436.172.0.1 to 36.175.255.25436.175.255.255262,142
4536.176.0.0/1436.176.0.1 to 36.179.255.25436.179.255.255262,142
4636.180.0.0/1436.180.0.1 to 36.183.255.25436.183.255.255262,142
4736.184.0.0/1436.184.0.1 to 36.187.255.25436.187.255.255262,142
4836.188.0.0/1436.188.0.1 to 36.191.255.25436.191.255.255262,142
4936.192.0.0/1436.192.0.1 to 36.195.255.25436.195.255.255262,142
5036.196.0.0/1436.196.0.1 to 36.199.255.25436.199.255.255262,142
5136.200.0.0/1436.200.0.1 to 36.203.255.25436.203.255.255262,142
5236.204.0.0/1436.204.0.1 to 36.207.255.25436.207.255.255262,142
5336.208.0.0/1436.208.0.1 to 36.211.255.25436.211.255.255262,142
5436.212.0.0/1436.212.0.1 to 36.215.255.25436.215.255.255262,142
5536.216.0.0/1436.216.0.1 to 36.219.255.25436.219.255.255262,142
5636.220.0.0/1436.220.0.1 to 36.223.255.25436.223.255.255262,142
5736.224.0.0/1436.224.0.1 to 36.227.255.25436.227.255.255262,142
5836.228.0.0/1436.228.0.1 to 36.231.255.25436.231.255.255262,142
5936.232.0.0/1436.232.0.1 to 36.235.255.25436.235.255.255262,142
6036.236.0.0/1436.236.0.1 to 36.239.255.25436.239.255.255262,142
6136.240.0.0/1436.240.0.1 to 36.243.255.25436.243.255.255262,142
6236.244.0.0/1436.244.0.1 to 36.247.255.25436.247.255.255262,142
6336.248.0.0/1436.248.0.1 to 36.251.255.25436.251.255.255262,142
6436.252.0.0/1436.252.0.1 to 36.255.255.25436.255.255.255262,142
6537.0.0.0/1437.0.0.1 to 37.3.255.25437.3.255.255262,142
6637.4.0.0/1437.4.0.1 to 37.7.255.25437.7.255.255262,142
6737.8.0.0/1437.8.0.1 to 37.11.255.25437.11.255.255262,142
6837.12.0.0/1437.12.0.1 to 37.15.255.25437.15.255.255262,142
6937.16.0.0/1437.16.0.1 to 37.19.255.25437.19.255.255262,142
7037.20.0.0/1437.20.0.1 to 37.23.255.25437.23.255.255262,142
7137.24.0.0/1437.24.0.1 to 37.27.255.25437.27.255.255262,142
7237.28.0.0/1437.28.0.1 to 37.31.255.25437.31.255.255262,142
7337.32.0.0/1437.32.0.1 to 37.35.255.25437.35.255.255262,142
7437.36.0.0/1437.36.0.1 to 37.39.255.25437.39.255.255262,142
7537.40.0.0/1437.40.0.1 to 37.43.255.25437.43.255.255262,142
7637.44.0.0/1437.44.0.1 to 37.47.255.25437.47.255.255262,142
7737.48.0.0/1437.48.0.1 to 37.51.255.25437.51.255.255262,142
7837.52.0.0/1437.52.0.1 to 37.55.255.25437.55.255.255262,142
7937.56.0.0/1437.56.0.1 to 37.59.255.25437.59.255.255262,142
8037.60.0.0/1437.60.0.1 to 37.63.255.25437.63.255.255262,142
8137.64.0.0/1437.64.0.1 to 37.67.255.25437.67.255.255262,142
8237.68.0.0/1437.68.0.1 to 37.71.255.25437.71.255.255262,142
8337.72.0.0/1437.72.0.1 to 37.75.255.25437.75.255.255262,142
8437.76.0.0/1437.76.0.1 to 37.79.255.25437.79.255.255262,142
8537.80.0.0/1437.80.0.1 to 37.83.255.25437.83.255.255262,142
8637.84.0.0/1437.84.0.1 to 37.87.255.25437.87.255.255262,142
8737.88.0.0/1437.88.0.1 to 37.91.255.25437.91.255.255262,142
8837.92.0.0/1437.92.0.1 to 37.95.255.25437.95.255.255262,142
8937.96.0.0/1437.96.0.1 to 37.99.255.25437.99.255.255262,142
9037.100.0.0/1437.100.0.1 to 37.103.255.25437.103.255.255262,142
9137.104.0.0/1437.104.0.1 to 37.107.255.25437.107.255.255262,142
9237.108.0.0/1437.108.0.1 to 37.111.255.25437.111.255.255262,142
9337.112.0.0/1437.112.0.1 to 37.115.255.25437.115.255.255262,142
9437.116.0.0/1437.116.0.1 to 37.119.255.25437.119.255.255262,142
9537.120.0.0/1437.120.0.1 to 37.123.255.25437.123.255.255262,142
9637.124.0.0/1437.124.0.1 to 37.127.255.25437.127.255.255262,142
9737.128.0.0/1437.128.0.1 to 37.131.255.25437.131.255.255262,142
9837.132.0.0/1437.132.0.1 to 37.135.255.25437.135.255.255262,142
9937.136.0.0/1437.136.0.1 to 37.139.255.25437.139.255.255262,142
10037.140.0.0/1437.140.0.1 to 37.143.255.25437.143.255.255262,142
10137.144.0.0/1437.144.0.1 to 37.147.255.25437.147.255.255262,142
10237.148.0.0/1437.148.0.1 to 37.151.255.25437.151.255.255262,142
10337.152.0.0/1437.152.0.1 to 37.155.255.25437.155.255.255262,142
10437.156.0.0/1437.156.0.1 to 37.159.255.25437.159.255.255262,142
10537.160.0.0/1437.160.0.1 to 37.163.255.25437.163.255.255262,142
10637.164.0.0/1437.164.0.1 to 37.167.255.25437.167.255.255262,142
10737.168.0.0/1437.168.0.1 to 37.171.255.25437.171.255.255262,142
10837.172.0.0/1437.172.0.1 to 37.175.255.25437.175.255.255262,142
10937.176.0.0/1437.176.0.1 to 37.179.255.25437.179.255.255262,142
11037.180.0.0/1437.180.0.1 to 37.183.255.25437.183.255.255262,142
11137.184.0.0/1437.184.0.1 to 37.187.255.25437.187.255.255262,142
11237.188.0.0/1437.188.0.1 to 37.191.255.25437.191.255.255262,142
11337.192.0.0/1437.192.0.1 to 37.195.255.25437.195.255.255262,142
11437.196.0.0/1437.196.0.1 to 37.199.255.25437.199.255.255262,142
11537.200.0.0/1437.200.0.1 to 37.203.255.25437.203.255.255262,142
11637.204.0.0/1437.204.0.1 to 37.207.255.25437.207.255.255262,142
11737.208.0.0/1437.208.0.1 to 37.211.255.25437.211.255.255262,142
11837.212.0.0/1437.212.0.1 to 37.215.255.25437.215.255.255262,142
11937.216.0.0/1437.216.0.1 to 37.219.255.25437.219.255.255262,142
12037.220.0.0/1437.220.0.1 to 37.223.255.25437.223.255.255262,142
12137.224.0.0/1437.224.0.1 to 37.227.255.25437.227.255.255262,142
12237.228.0.0/1437.228.0.1 to 37.231.255.25437.231.255.255262,142
12337.232.0.0/1437.232.0.1 to 37.235.255.25437.235.255.255262,142
12437.236.0.0/1437.236.0.1 to 37.239.255.25437.239.255.255262,142
12537.240.0.0/1437.240.0.1 to 37.243.255.25437.243.255.255262,142
12637.244.0.0/1437.244.0.1 to 37.247.255.25437.247.255.255262,142
12737.248.0.0/1437.248.0.1 to 37.251.255.25437.251.255.255262,142
12837.252.0.0/1437.252.0.1 to 37.255.255.25437.255.255.255262,142

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.