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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.

Network80.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
80.0.0.0
Broadcast address
80.255.255.255
First usable
80.0.0.1
Last usable
80.255.255.254
Usable hosts
16,777,214 (16,777,216 less the network and broadcast addresses)
Subnet mask
255.0.0.0
Wildcard mask
0.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/8
Type
Public public
Old class
A (default /8)
As numbers
Hex 50000000 · Integer 1342177280 to 1358954495
Reverse DNS zone
80.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01010000..00000000.00000000.0000000080.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network01010000..00000000.00000000.0000000080.0.0.0
Broadcast01010000..11111111.11111111.1111111180.255.255.255
Split into smaller subnets/15
/9 (2)/10 (4)/11 (8)/12 (16)/13 (32)/14 (64)/15 (128)/16 (256)/17 (512)/18 (1,024)/19 (2,048)/20 (4,096)

80.0.0.0/8 makes 128 subnets of /15.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
180.0.0.0/1580.0.0.1 to 80.1.255.25480.1.255.255131,070
280.2.0.0/1580.2.0.1 to 80.3.255.25480.3.255.255131,070
380.4.0.0/1580.4.0.1 to 80.5.255.25480.5.255.255131,070
480.6.0.0/1580.6.0.1 to 80.7.255.25480.7.255.255131,070
580.8.0.0/1580.8.0.1 to 80.9.255.25480.9.255.255131,070
680.10.0.0/1580.10.0.1 to 80.11.255.25480.11.255.255131,070
780.12.0.0/1580.12.0.1 to 80.13.255.25480.13.255.255131,070
880.14.0.0/1580.14.0.1 to 80.15.255.25480.15.255.255131,070
980.16.0.0/1580.16.0.1 to 80.17.255.25480.17.255.255131,070
1080.18.0.0/1580.18.0.1 to 80.19.255.25480.19.255.255131,070
1180.20.0.0/1580.20.0.1 to 80.21.255.25480.21.255.255131,070
1280.22.0.0/1580.22.0.1 to 80.23.255.25480.23.255.255131,070
1380.24.0.0/1580.24.0.1 to 80.25.255.25480.25.255.255131,070
1480.26.0.0/1580.26.0.1 to 80.27.255.25480.27.255.255131,070
1580.28.0.0/1580.28.0.1 to 80.29.255.25480.29.255.255131,070
1680.30.0.0/1580.30.0.1 to 80.31.255.25480.31.255.255131,070
1780.32.0.0/1580.32.0.1 to 80.33.255.25480.33.255.255131,070
1880.34.0.0/1580.34.0.1 to 80.35.255.25480.35.255.255131,070
1980.36.0.0/1580.36.0.1 to 80.37.255.25480.37.255.255131,070
2080.38.0.0/1580.38.0.1 to 80.39.255.25480.39.255.255131,070
2180.40.0.0/1580.40.0.1 to 80.41.255.25480.41.255.255131,070
2280.42.0.0/1580.42.0.1 to 80.43.255.25480.43.255.255131,070
2380.44.0.0/1580.44.0.1 to 80.45.255.25480.45.255.255131,070
2480.46.0.0/1580.46.0.1 to 80.47.255.25480.47.255.255131,070
2580.48.0.0/1580.48.0.1 to 80.49.255.25480.49.255.255131,070
2680.50.0.0/1580.50.0.1 to 80.51.255.25480.51.255.255131,070
2780.52.0.0/1580.52.0.1 to 80.53.255.25480.53.255.255131,070
2880.54.0.0/1580.54.0.1 to 80.55.255.25480.55.255.255131,070
2980.56.0.0/1580.56.0.1 to 80.57.255.25480.57.255.255131,070
3080.58.0.0/1580.58.0.1 to 80.59.255.25480.59.255.255131,070
3180.60.0.0/1580.60.0.1 to 80.61.255.25480.61.255.255131,070
3280.62.0.0/1580.62.0.1 to 80.63.255.25480.63.255.255131,070
3380.64.0.0/1580.64.0.1 to 80.65.255.25480.65.255.255131,070
3480.66.0.0/1580.66.0.1 to 80.67.255.25480.67.255.255131,070
3580.68.0.0/1580.68.0.1 to 80.69.255.25480.69.255.255131,070
3680.70.0.0/1580.70.0.1 to 80.71.255.25480.71.255.255131,070
3780.72.0.0/1580.72.0.1 to 80.73.255.25480.73.255.255131,070
3880.74.0.0/1580.74.0.1 to 80.75.255.25480.75.255.255131,070
3980.76.0.0/1580.76.0.1 to 80.77.255.25480.77.255.255131,070
4080.78.0.0/1580.78.0.1 to 80.79.255.25480.79.255.255131,070
4180.80.0.0/1580.80.0.1 to 80.81.255.25480.81.255.255131,070
4280.82.0.0/1580.82.0.1 to 80.83.255.25480.83.255.255131,070
4380.84.0.0/1580.84.0.1 to 80.85.255.25480.85.255.255131,070
4480.86.0.0/1580.86.0.1 to 80.87.255.25480.87.255.255131,070
4580.88.0.0/1580.88.0.1 to 80.89.255.25480.89.255.255131,070
4680.90.0.0/1580.90.0.1 to 80.91.255.25480.91.255.255131,070
4780.92.0.0/1580.92.0.1 to 80.93.255.25480.93.255.255131,070
4880.94.0.0/1580.94.0.1 to 80.95.255.25480.95.255.255131,070
4980.96.0.0/1580.96.0.1 to 80.97.255.25480.97.255.255131,070
5080.98.0.0/1580.98.0.1 to 80.99.255.25480.99.255.255131,070
5180.100.0.0/1580.100.0.1 to 80.101.255.25480.101.255.255131,070
5280.102.0.0/1580.102.0.1 to 80.103.255.25480.103.255.255131,070
5380.104.0.0/1580.104.0.1 to 80.105.255.25480.105.255.255131,070
5480.106.0.0/1580.106.0.1 to 80.107.255.25480.107.255.255131,070
5580.108.0.0/1580.108.0.1 to 80.109.255.25480.109.255.255131,070
5680.110.0.0/1580.110.0.1 to 80.111.255.25480.111.255.255131,070
5780.112.0.0/1580.112.0.1 to 80.113.255.25480.113.255.255131,070
5880.114.0.0/1580.114.0.1 to 80.115.255.25480.115.255.255131,070
5980.116.0.0/1580.116.0.1 to 80.117.255.25480.117.255.255131,070
6080.118.0.0/1580.118.0.1 to 80.119.255.25480.119.255.255131,070
6180.120.0.0/1580.120.0.1 to 80.121.255.25480.121.255.255131,070
6280.122.0.0/1580.122.0.1 to 80.123.255.25480.123.255.255131,070
6380.124.0.0/1580.124.0.1 to 80.125.255.25480.125.255.255131,070
6480.126.0.0/1580.126.0.1 to 80.127.255.25480.127.255.255131,070
6580.128.0.0/1580.128.0.1 to 80.129.255.25480.129.255.255131,070
6680.130.0.0/1580.130.0.1 to 80.131.255.25480.131.255.255131,070
6780.132.0.0/1580.132.0.1 to 80.133.255.25480.133.255.255131,070
6880.134.0.0/1580.134.0.1 to 80.135.255.25480.135.255.255131,070
6980.136.0.0/1580.136.0.1 to 80.137.255.25480.137.255.255131,070
7080.138.0.0/1580.138.0.1 to 80.139.255.25480.139.255.255131,070
7180.140.0.0/1580.140.0.1 to 80.141.255.25480.141.255.255131,070
7280.142.0.0/1580.142.0.1 to 80.143.255.25480.143.255.255131,070
7380.144.0.0/1580.144.0.1 to 80.145.255.25480.145.255.255131,070
7480.146.0.0/1580.146.0.1 to 80.147.255.25480.147.255.255131,070
7580.148.0.0/1580.148.0.1 to 80.149.255.25480.149.255.255131,070
7680.150.0.0/1580.150.0.1 to 80.151.255.25480.151.255.255131,070
7780.152.0.0/1580.152.0.1 to 80.153.255.25480.153.255.255131,070
7880.154.0.0/1580.154.0.1 to 80.155.255.25480.155.255.255131,070
7980.156.0.0/1580.156.0.1 to 80.157.255.25480.157.255.255131,070
8080.158.0.0/1580.158.0.1 to 80.159.255.25480.159.255.255131,070
8180.160.0.0/1580.160.0.1 to 80.161.255.25480.161.255.255131,070
8280.162.0.0/1580.162.0.1 to 80.163.255.25480.163.255.255131,070
8380.164.0.0/1580.164.0.1 to 80.165.255.25480.165.255.255131,070
8480.166.0.0/1580.166.0.1 to 80.167.255.25480.167.255.255131,070
8580.168.0.0/1580.168.0.1 to 80.169.255.25480.169.255.255131,070
8680.170.0.0/1580.170.0.1 to 80.171.255.25480.171.255.255131,070
8780.172.0.0/1580.172.0.1 to 80.173.255.25480.173.255.255131,070
8880.174.0.0/1580.174.0.1 to 80.175.255.25480.175.255.255131,070
8980.176.0.0/1580.176.0.1 to 80.177.255.25480.177.255.255131,070
9080.178.0.0/1580.178.0.1 to 80.179.255.25480.179.255.255131,070
9180.180.0.0/1580.180.0.1 to 80.181.255.25480.181.255.255131,070
9280.182.0.0/1580.182.0.1 to 80.183.255.25480.183.255.255131,070
9380.184.0.0/1580.184.0.1 to 80.185.255.25480.185.255.255131,070
9480.186.0.0/1580.186.0.1 to 80.187.255.25480.187.255.255131,070
9580.188.0.0/1580.188.0.1 to 80.189.255.25480.189.255.255131,070
9680.190.0.0/1580.190.0.1 to 80.191.255.25480.191.255.255131,070
9780.192.0.0/1580.192.0.1 to 80.193.255.25480.193.255.255131,070
9880.194.0.0/1580.194.0.1 to 80.195.255.25480.195.255.255131,070
9980.196.0.0/1580.196.0.1 to 80.197.255.25480.197.255.255131,070
10080.198.0.0/1580.198.0.1 to 80.199.255.25480.199.255.255131,070
10180.200.0.0/1580.200.0.1 to 80.201.255.25480.201.255.255131,070
10280.202.0.0/1580.202.0.1 to 80.203.255.25480.203.255.255131,070
10380.204.0.0/1580.204.0.1 to 80.205.255.25480.205.255.255131,070
10480.206.0.0/1580.206.0.1 to 80.207.255.25480.207.255.255131,070
10580.208.0.0/1580.208.0.1 to 80.209.255.25480.209.255.255131,070
10680.210.0.0/1580.210.0.1 to 80.211.255.25480.211.255.255131,070
10780.212.0.0/1580.212.0.1 to 80.213.255.25480.213.255.255131,070
10880.214.0.0/1580.214.0.1 to 80.215.255.25480.215.255.255131,070
10980.216.0.0/1580.216.0.1 to 80.217.255.25480.217.255.255131,070
11080.218.0.0/1580.218.0.1 to 80.219.255.25480.219.255.255131,070
11180.220.0.0/1580.220.0.1 to 80.221.255.25480.221.255.255131,070
11280.222.0.0/1580.222.0.1 to 80.223.255.25480.223.255.255131,070
11380.224.0.0/1580.224.0.1 to 80.225.255.25480.225.255.255131,070
11480.226.0.0/1580.226.0.1 to 80.227.255.25480.227.255.255131,070
11580.228.0.0/1580.228.0.1 to 80.229.255.25480.229.255.255131,070
11680.230.0.0/1580.230.0.1 to 80.231.255.25480.231.255.255131,070
11780.232.0.0/1580.232.0.1 to 80.233.255.25480.233.255.255131,070
11880.234.0.0/1580.234.0.1 to 80.235.255.25480.235.255.255131,070
11980.236.0.0/1580.236.0.1 to 80.237.255.25480.237.255.255131,070
12080.238.0.0/1580.238.0.1 to 80.239.255.25480.239.255.255131,070
12180.240.0.0/1580.240.0.1 to 80.241.255.25480.241.255.255131,070
12280.242.0.0/1580.242.0.1 to 80.243.255.25480.243.255.255131,070
12380.244.0.0/1580.244.0.1 to 80.245.255.25480.245.255.255131,070
12480.246.0.0/1580.246.0.1 to 80.247.255.25480.247.255.255131,070
12580.248.0.0/1580.248.0.1 to 80.249.255.25480.249.255.255131,070
12680.250.0.0/1580.250.0.1 to 80.251.255.25480.251.255.255131,070
12780.252.0.0/1580.252.0.1 to 80.253.255.25480.253.255.255131,070
12880.254.0.0/1580.254.0.1 to 80.255.255.25480.255.255.255131,070

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.