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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.

Network80.32.0.0/12
Usable hosts1,048,574
Subnet mask255.240.0.0
Addresses1,048,576
Network address
80.32.0.0
Broadcast address
80.47.255.255
First usable
80.32.0.1
Last usable
80.47.255.254
Usable hosts
1,048,574 (1,048,576 less the network and broadcast addresses)
Subnet mask
255.240.0.0
Wildcard mask
0.15.255.255 (Cisco ACLs, OSPF)
Prefix length
/12
Type
Public public
Old class
A (default /8)
As numbers
Hex 50200000 · Integer 1344274432 to 1345323007
Reverse DNS zones
32.80.in-addr.arpa
33.80.in-addr.arpa
34.80.in-addr.arpa
35.80.in-addr.arpa
36.80.in-addr.arpa
37.80.in-addr.arpa
38.80.in-addr.arpa
39.80.in-addr.arpa
40.80.in-addr.arpa
41.80.in-addr.arpa
42.80.in-addr.arpa
43.80.in-addr.arpa
44.80.in-addr.arpa
45.80.in-addr.arpa
46.80.in-addr.arpa
47.80.in-addr.arpa
/12 is not on a 8-bit boundary, so it takes 16 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01010000.00100000.00000000.0000000080.32.0.0
Subnet mask11111111.11110000.00000000.00000000255.240.0.0
Network01010000.00100000.00000000.0000000080.32.0.0
Broadcast01010000.00101111.11111111.1111111180.47.255.255
Split into smaller subnets/19
/13 (2)/14 (4)/15 (8)/16 (16)/17 (32)/18 (64)/19 (128)/20 (256)/21 (512)/22 (1,024)/23 (2,048)/24 (4,096)

80.32.0.0/12 makes 128 subnets of /19.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
180.32.0.0/1980.32.0.1 to 80.32.31.25480.32.31.2558,190
280.32.32.0/1980.32.32.1 to 80.32.63.25480.32.63.2558,190
380.32.64.0/1980.32.64.1 to 80.32.95.25480.32.95.2558,190
480.32.96.0/1980.32.96.1 to 80.32.127.25480.32.127.2558,190
580.32.128.0/1980.32.128.1 to 80.32.159.25480.32.159.2558,190
680.32.160.0/1980.32.160.1 to 80.32.191.25480.32.191.2558,190
780.32.192.0/1980.32.192.1 to 80.32.223.25480.32.223.2558,190
880.32.224.0/1980.32.224.1 to 80.32.255.25480.32.255.2558,190
980.33.0.0/1980.33.0.1 to 80.33.31.25480.33.31.2558,190
1080.33.32.0/1980.33.32.1 to 80.33.63.25480.33.63.2558,190
1180.33.64.0/1980.33.64.1 to 80.33.95.25480.33.95.2558,190
1280.33.96.0/1980.33.96.1 to 80.33.127.25480.33.127.2558,190
1380.33.128.0/1980.33.128.1 to 80.33.159.25480.33.159.2558,190
1480.33.160.0/1980.33.160.1 to 80.33.191.25480.33.191.2558,190
1580.33.192.0/1980.33.192.1 to 80.33.223.25480.33.223.2558,190
1680.33.224.0/1980.33.224.1 to 80.33.255.25480.33.255.2558,190
1780.34.0.0/1980.34.0.1 to 80.34.31.25480.34.31.2558,190
1880.34.32.0/1980.34.32.1 to 80.34.63.25480.34.63.2558,190
1980.34.64.0/1980.34.64.1 to 80.34.95.25480.34.95.2558,190
2080.34.96.0/1980.34.96.1 to 80.34.127.25480.34.127.2558,190
2180.34.128.0/1980.34.128.1 to 80.34.159.25480.34.159.2558,190
2280.34.160.0/1980.34.160.1 to 80.34.191.25480.34.191.2558,190
2380.34.192.0/1980.34.192.1 to 80.34.223.25480.34.223.2558,190
2480.34.224.0/1980.34.224.1 to 80.34.255.25480.34.255.2558,190
2580.35.0.0/1980.35.0.1 to 80.35.31.25480.35.31.2558,190
2680.35.32.0/1980.35.32.1 to 80.35.63.25480.35.63.2558,190
2780.35.64.0/1980.35.64.1 to 80.35.95.25480.35.95.2558,190
2880.35.96.0/1980.35.96.1 to 80.35.127.25480.35.127.2558,190
2980.35.128.0/1980.35.128.1 to 80.35.159.25480.35.159.2558,190
3080.35.160.0/1980.35.160.1 to 80.35.191.25480.35.191.2558,190
3180.35.192.0/1980.35.192.1 to 80.35.223.25480.35.223.2558,190
3280.35.224.0/1980.35.224.1 to 80.35.255.25480.35.255.2558,190
3380.36.0.0/1980.36.0.1 to 80.36.31.25480.36.31.2558,190
3480.36.32.0/1980.36.32.1 to 80.36.63.25480.36.63.2558,190
3580.36.64.0/1980.36.64.1 to 80.36.95.25480.36.95.2558,190
3680.36.96.0/1980.36.96.1 to 80.36.127.25480.36.127.2558,190
3780.36.128.0/1980.36.128.1 to 80.36.159.25480.36.159.2558,190
3880.36.160.0/1980.36.160.1 to 80.36.191.25480.36.191.2558,190
3980.36.192.0/1980.36.192.1 to 80.36.223.25480.36.223.2558,190
4080.36.224.0/1980.36.224.1 to 80.36.255.25480.36.255.2558,190
4180.37.0.0/1980.37.0.1 to 80.37.31.25480.37.31.2558,190
4280.37.32.0/1980.37.32.1 to 80.37.63.25480.37.63.2558,190
4380.37.64.0/1980.37.64.1 to 80.37.95.25480.37.95.2558,190
4480.37.96.0/1980.37.96.1 to 80.37.127.25480.37.127.2558,190
4580.37.128.0/1980.37.128.1 to 80.37.159.25480.37.159.2558,190
4680.37.160.0/1980.37.160.1 to 80.37.191.25480.37.191.2558,190
4780.37.192.0/1980.37.192.1 to 80.37.223.25480.37.223.2558,190
4880.37.224.0/1980.37.224.1 to 80.37.255.25480.37.255.2558,190
4980.38.0.0/1980.38.0.1 to 80.38.31.25480.38.31.2558,190
5080.38.32.0/1980.38.32.1 to 80.38.63.25480.38.63.2558,190
5180.38.64.0/1980.38.64.1 to 80.38.95.25480.38.95.2558,190
5280.38.96.0/1980.38.96.1 to 80.38.127.25480.38.127.2558,190
5380.38.128.0/1980.38.128.1 to 80.38.159.25480.38.159.2558,190
5480.38.160.0/1980.38.160.1 to 80.38.191.25480.38.191.2558,190
5580.38.192.0/1980.38.192.1 to 80.38.223.25480.38.223.2558,190
5680.38.224.0/1980.38.224.1 to 80.38.255.25480.38.255.2558,190
5780.39.0.0/1980.39.0.1 to 80.39.31.25480.39.31.2558,190
5880.39.32.0/1980.39.32.1 to 80.39.63.25480.39.63.2558,190
5980.39.64.0/1980.39.64.1 to 80.39.95.25480.39.95.2558,190
6080.39.96.0/1980.39.96.1 to 80.39.127.25480.39.127.2558,190
6180.39.128.0/1980.39.128.1 to 80.39.159.25480.39.159.2558,190
6280.39.160.0/1980.39.160.1 to 80.39.191.25480.39.191.2558,190
6380.39.192.0/1980.39.192.1 to 80.39.223.25480.39.223.2558,190
6480.39.224.0/1980.39.224.1 to 80.39.255.25480.39.255.2558,190
6580.40.0.0/1980.40.0.1 to 80.40.31.25480.40.31.2558,190
6680.40.32.0/1980.40.32.1 to 80.40.63.25480.40.63.2558,190
6780.40.64.0/1980.40.64.1 to 80.40.95.25480.40.95.2558,190
6880.40.96.0/1980.40.96.1 to 80.40.127.25480.40.127.2558,190
6980.40.128.0/1980.40.128.1 to 80.40.159.25480.40.159.2558,190
7080.40.160.0/1980.40.160.1 to 80.40.191.25480.40.191.2558,190
7180.40.192.0/1980.40.192.1 to 80.40.223.25480.40.223.2558,190
7280.40.224.0/1980.40.224.1 to 80.40.255.25480.40.255.2558,190
7380.41.0.0/1980.41.0.1 to 80.41.31.25480.41.31.2558,190
7480.41.32.0/1980.41.32.1 to 80.41.63.25480.41.63.2558,190
7580.41.64.0/1980.41.64.1 to 80.41.95.25480.41.95.2558,190
7680.41.96.0/1980.41.96.1 to 80.41.127.25480.41.127.2558,190
7780.41.128.0/1980.41.128.1 to 80.41.159.25480.41.159.2558,190
7880.41.160.0/1980.41.160.1 to 80.41.191.25480.41.191.2558,190
7980.41.192.0/1980.41.192.1 to 80.41.223.25480.41.223.2558,190
8080.41.224.0/1980.41.224.1 to 80.41.255.25480.41.255.2558,190
8180.42.0.0/1980.42.0.1 to 80.42.31.25480.42.31.2558,190
8280.42.32.0/1980.42.32.1 to 80.42.63.25480.42.63.2558,190
8380.42.64.0/1980.42.64.1 to 80.42.95.25480.42.95.2558,190
8480.42.96.0/1980.42.96.1 to 80.42.127.25480.42.127.2558,190
8580.42.128.0/1980.42.128.1 to 80.42.159.25480.42.159.2558,190
8680.42.160.0/1980.42.160.1 to 80.42.191.25480.42.191.2558,190
8780.42.192.0/1980.42.192.1 to 80.42.223.25480.42.223.2558,190
8880.42.224.0/1980.42.224.1 to 80.42.255.25480.42.255.2558,190
8980.43.0.0/1980.43.0.1 to 80.43.31.25480.43.31.2558,190
9080.43.32.0/1980.43.32.1 to 80.43.63.25480.43.63.2558,190
9180.43.64.0/1980.43.64.1 to 80.43.95.25480.43.95.2558,190
9280.43.96.0/1980.43.96.1 to 80.43.127.25480.43.127.2558,190
9380.43.128.0/1980.43.128.1 to 80.43.159.25480.43.159.2558,190
9480.43.160.0/1980.43.160.1 to 80.43.191.25480.43.191.2558,190
9580.43.192.0/1980.43.192.1 to 80.43.223.25480.43.223.2558,190
9680.43.224.0/1980.43.224.1 to 80.43.255.25480.43.255.2558,190
9780.44.0.0/1980.44.0.1 to 80.44.31.25480.44.31.2558,190
9880.44.32.0/1980.44.32.1 to 80.44.63.25480.44.63.2558,190
9980.44.64.0/1980.44.64.1 to 80.44.95.25480.44.95.2558,190
10080.44.96.0/1980.44.96.1 to 80.44.127.25480.44.127.2558,190
10180.44.128.0/1980.44.128.1 to 80.44.159.25480.44.159.2558,190
10280.44.160.0/1980.44.160.1 to 80.44.191.25480.44.191.2558,190
10380.44.192.0/1980.44.192.1 to 80.44.223.25480.44.223.2558,190
10480.44.224.0/1980.44.224.1 to 80.44.255.25480.44.255.2558,190
10580.45.0.0/1980.45.0.1 to 80.45.31.25480.45.31.2558,190
10680.45.32.0/1980.45.32.1 to 80.45.63.25480.45.63.2558,190
10780.45.64.0/1980.45.64.1 to 80.45.95.25480.45.95.2558,190
10880.45.96.0/1980.45.96.1 to 80.45.127.25480.45.127.2558,190
10980.45.128.0/1980.45.128.1 to 80.45.159.25480.45.159.2558,190
11080.45.160.0/1980.45.160.1 to 80.45.191.25480.45.191.2558,190
11180.45.192.0/1980.45.192.1 to 80.45.223.25480.45.223.2558,190
11280.45.224.0/1980.45.224.1 to 80.45.255.25480.45.255.2558,190
11380.46.0.0/1980.46.0.1 to 80.46.31.25480.46.31.2558,190
11480.46.32.0/1980.46.32.1 to 80.46.63.25480.46.63.2558,190
11580.46.64.0/1980.46.64.1 to 80.46.95.25480.46.95.2558,190
11680.46.96.0/1980.46.96.1 to 80.46.127.25480.46.127.2558,190
11780.46.128.0/1980.46.128.1 to 80.46.159.25480.46.159.2558,190
11880.46.160.0/1980.46.160.1 to 80.46.191.25480.46.191.2558,190
11980.46.192.0/1980.46.192.1 to 80.46.223.25480.46.223.2558,190
12080.46.224.0/1980.46.224.1 to 80.46.255.25480.46.255.2558,190
12180.47.0.0/1980.47.0.1 to 80.47.31.25480.47.31.2558,190
12280.47.32.0/1980.47.32.1 to 80.47.63.25480.47.63.2558,190
12380.47.64.0/1980.47.64.1 to 80.47.95.25480.47.95.2558,190
12480.47.96.0/1980.47.96.1 to 80.47.127.25480.47.127.2558,190
12580.47.128.0/1980.47.128.1 to 80.47.159.25480.47.159.2558,190
12680.47.160.0/1980.47.160.1 to 80.47.191.25480.47.191.2558,190
12780.47.192.0/1980.47.192.1 to 80.47.223.25480.47.223.2558,190
12880.47.224.0/1980.47.224.1 to 80.47.255.25480.47.255.2558,190

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.