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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.

Network80.210.0.0/16
Usable hosts65,534
Subnet mask255.255.0.0
Addresses65,536
Network address
80.210.0.0
Broadcast address
80.210.255.255
First usable
80.210.0.1
Last usable
80.210.255.254
Usable hosts
65,534 (65,536 less the network and broadcast addresses)
Subnet mask
255.255.0.0
Wildcard mask
0.0.255.255 (Cisco ACLs, OSPF)
Prefix length
/16
Type
Public public
Old class
A (default /8)
As numbers
Hex 50D20000 · Integer 1355939840 to 1356005375
Reverse DNS zone
210.80.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01010000.11010010..00000000.0000000080.210.0.0
Subnet mask11111111.11111111..00000000.00000000255.255.0.0
Network01010000.11010010..00000000.0000000080.210.0.0
Broadcast01010000.11010010..11111111.1111111180.210.255.255
Split into smaller subnets/23
/17 (2)/18 (4)/19 (8)/20 (16)/21 (32)/22 (64)/23 (128)/24 (256)/25 (512)/26 (1,024)/27 (2,048)/28 (4,096)

80.210.0.0/16 makes 128 subnets of /23.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
180.210.0.0/2380.210.0.1 to 80.210.1.25480.210.1.255510
280.210.2.0/2380.210.2.1 to 80.210.3.25480.210.3.255510
380.210.4.0/2380.210.4.1 to 80.210.5.25480.210.5.255510
480.210.6.0/2380.210.6.1 to 80.210.7.25480.210.7.255510
580.210.8.0/2380.210.8.1 to 80.210.9.25480.210.9.255510
680.210.10.0/2380.210.10.1 to 80.210.11.25480.210.11.255510
780.210.12.0/2380.210.12.1 to 80.210.13.25480.210.13.255510
880.210.14.0/2380.210.14.1 to 80.210.15.25480.210.15.255510
980.210.16.0/2380.210.16.1 to 80.210.17.25480.210.17.255510
1080.210.18.0/2380.210.18.1 to 80.210.19.25480.210.19.255510
1180.210.20.0/2380.210.20.1 to 80.210.21.25480.210.21.255510
1280.210.22.0/2380.210.22.1 to 80.210.23.25480.210.23.255510
1380.210.24.0/2380.210.24.1 to 80.210.25.25480.210.25.255510
1480.210.26.0/2380.210.26.1 to 80.210.27.25480.210.27.255510
1580.210.28.0/2380.210.28.1 to 80.210.29.25480.210.29.255510
1680.210.30.0/2380.210.30.1 to 80.210.31.25480.210.31.255510
1780.210.32.0/2380.210.32.1 to 80.210.33.25480.210.33.255510
1880.210.34.0/2380.210.34.1 to 80.210.35.25480.210.35.255510
1980.210.36.0/2380.210.36.1 to 80.210.37.25480.210.37.255510
2080.210.38.0/2380.210.38.1 to 80.210.39.25480.210.39.255510
2180.210.40.0/2380.210.40.1 to 80.210.41.25480.210.41.255510
2280.210.42.0/2380.210.42.1 to 80.210.43.25480.210.43.255510
2380.210.44.0/2380.210.44.1 to 80.210.45.25480.210.45.255510
2480.210.46.0/2380.210.46.1 to 80.210.47.25480.210.47.255510
2580.210.48.0/2380.210.48.1 to 80.210.49.25480.210.49.255510
2680.210.50.0/2380.210.50.1 to 80.210.51.25480.210.51.255510
2780.210.52.0/2380.210.52.1 to 80.210.53.25480.210.53.255510
2880.210.54.0/2380.210.54.1 to 80.210.55.25480.210.55.255510
2980.210.56.0/2380.210.56.1 to 80.210.57.25480.210.57.255510
3080.210.58.0/2380.210.58.1 to 80.210.59.25480.210.59.255510
3180.210.60.0/2380.210.60.1 to 80.210.61.25480.210.61.255510
3280.210.62.0/2380.210.62.1 to 80.210.63.25480.210.63.255510
3380.210.64.0/2380.210.64.1 to 80.210.65.25480.210.65.255510
3480.210.66.0/2380.210.66.1 to 80.210.67.25480.210.67.255510
3580.210.68.0/2380.210.68.1 to 80.210.69.25480.210.69.255510
3680.210.70.0/2380.210.70.1 to 80.210.71.25480.210.71.255510
3780.210.72.0/2380.210.72.1 to 80.210.73.25480.210.73.255510
3880.210.74.0/2380.210.74.1 to 80.210.75.25480.210.75.255510
3980.210.76.0/2380.210.76.1 to 80.210.77.25480.210.77.255510
4080.210.78.0/2380.210.78.1 to 80.210.79.25480.210.79.255510
4180.210.80.0/2380.210.80.1 to 80.210.81.25480.210.81.255510
4280.210.82.0/2380.210.82.1 to 80.210.83.25480.210.83.255510
4380.210.84.0/2380.210.84.1 to 80.210.85.25480.210.85.255510
4480.210.86.0/2380.210.86.1 to 80.210.87.25480.210.87.255510
4580.210.88.0/2380.210.88.1 to 80.210.89.25480.210.89.255510
4680.210.90.0/2380.210.90.1 to 80.210.91.25480.210.91.255510
4780.210.92.0/2380.210.92.1 to 80.210.93.25480.210.93.255510
4880.210.94.0/2380.210.94.1 to 80.210.95.25480.210.95.255510
4980.210.96.0/2380.210.96.1 to 80.210.97.25480.210.97.255510
5080.210.98.0/2380.210.98.1 to 80.210.99.25480.210.99.255510
5180.210.100.0/2380.210.100.1 to 80.210.101.25480.210.101.255510
5280.210.102.0/2380.210.102.1 to 80.210.103.25480.210.103.255510
5380.210.104.0/2380.210.104.1 to 80.210.105.25480.210.105.255510
5480.210.106.0/2380.210.106.1 to 80.210.107.25480.210.107.255510
5580.210.108.0/2380.210.108.1 to 80.210.109.25480.210.109.255510
5680.210.110.0/2380.210.110.1 to 80.210.111.25480.210.111.255510
5780.210.112.0/2380.210.112.1 to 80.210.113.25480.210.113.255510
5880.210.114.0/2380.210.114.1 to 80.210.115.25480.210.115.255510
5980.210.116.0/2380.210.116.1 to 80.210.117.25480.210.117.255510
6080.210.118.0/2380.210.118.1 to 80.210.119.25480.210.119.255510
6180.210.120.0/2380.210.120.1 to 80.210.121.25480.210.121.255510
6280.210.122.0/2380.210.122.1 to 80.210.123.25480.210.123.255510
6380.210.124.0/2380.210.124.1 to 80.210.125.25480.210.125.255510
6480.210.126.0/2380.210.126.1 to 80.210.127.25480.210.127.255510
6580.210.128.0/2380.210.128.1 to 80.210.129.25480.210.129.255510
6680.210.130.0/2380.210.130.1 to 80.210.131.25480.210.131.255510
6780.210.132.0/2380.210.132.1 to 80.210.133.25480.210.133.255510
6880.210.134.0/2380.210.134.1 to 80.210.135.25480.210.135.255510
6980.210.136.0/2380.210.136.1 to 80.210.137.25480.210.137.255510
7080.210.138.0/2380.210.138.1 to 80.210.139.25480.210.139.255510
7180.210.140.0/2380.210.140.1 to 80.210.141.25480.210.141.255510
7280.210.142.0/2380.210.142.1 to 80.210.143.25480.210.143.255510
7380.210.144.0/2380.210.144.1 to 80.210.145.25480.210.145.255510
7480.210.146.0/2380.210.146.1 to 80.210.147.25480.210.147.255510
7580.210.148.0/2380.210.148.1 to 80.210.149.25480.210.149.255510
7680.210.150.0/2380.210.150.1 to 80.210.151.25480.210.151.255510
7780.210.152.0/2380.210.152.1 to 80.210.153.25480.210.153.255510
7880.210.154.0/2380.210.154.1 to 80.210.155.25480.210.155.255510
7980.210.156.0/2380.210.156.1 to 80.210.157.25480.210.157.255510
8080.210.158.0/2380.210.158.1 to 80.210.159.25480.210.159.255510
8180.210.160.0/2380.210.160.1 to 80.210.161.25480.210.161.255510
8280.210.162.0/2380.210.162.1 to 80.210.163.25480.210.163.255510
8380.210.164.0/2380.210.164.1 to 80.210.165.25480.210.165.255510
8480.210.166.0/2380.210.166.1 to 80.210.167.25480.210.167.255510
8580.210.168.0/2380.210.168.1 to 80.210.169.25480.210.169.255510
8680.210.170.0/2380.210.170.1 to 80.210.171.25480.210.171.255510
8780.210.172.0/2380.210.172.1 to 80.210.173.25480.210.173.255510
8880.210.174.0/2380.210.174.1 to 80.210.175.25480.210.175.255510
8980.210.176.0/2380.210.176.1 to 80.210.177.25480.210.177.255510
9080.210.178.0/2380.210.178.1 to 80.210.179.25480.210.179.255510
9180.210.180.0/2380.210.180.1 to 80.210.181.25480.210.181.255510
9280.210.182.0/2380.210.182.1 to 80.210.183.25480.210.183.255510
9380.210.184.0/2380.210.184.1 to 80.210.185.25480.210.185.255510
9480.210.186.0/2380.210.186.1 to 80.210.187.25480.210.187.255510
9580.210.188.0/2380.210.188.1 to 80.210.189.25480.210.189.255510
9680.210.190.0/2380.210.190.1 to 80.210.191.25480.210.191.255510
9780.210.192.0/2380.210.192.1 to 80.210.193.25480.210.193.255510
9880.210.194.0/2380.210.194.1 to 80.210.195.25480.210.195.255510
9980.210.196.0/2380.210.196.1 to 80.210.197.25480.210.197.255510
10080.210.198.0/2380.210.198.1 to 80.210.199.25480.210.199.255510
10180.210.200.0/2380.210.200.1 to 80.210.201.25480.210.201.255510
10280.210.202.0/2380.210.202.1 to 80.210.203.25480.210.203.255510
10380.210.204.0/2380.210.204.1 to 80.210.205.25480.210.205.255510
10480.210.206.0/2380.210.206.1 to 80.210.207.25480.210.207.255510
10580.210.208.0/2380.210.208.1 to 80.210.209.25480.210.209.255510
10680.210.210.0/2380.210.210.1 to 80.210.211.25480.210.211.255510
10780.210.212.0/2380.210.212.1 to 80.210.213.25480.210.213.255510
10880.210.214.0/2380.210.214.1 to 80.210.215.25480.210.215.255510
10980.210.216.0/2380.210.216.1 to 80.210.217.25480.210.217.255510
11080.210.218.0/2380.210.218.1 to 80.210.219.25480.210.219.255510
11180.210.220.0/2380.210.220.1 to 80.210.221.25480.210.221.255510
11280.210.222.0/2380.210.222.1 to 80.210.223.25480.210.223.255510
11380.210.224.0/2380.210.224.1 to 80.210.225.25480.210.225.255510
11480.210.226.0/2380.210.226.1 to 80.210.227.25480.210.227.255510
11580.210.228.0/2380.210.228.1 to 80.210.229.25480.210.229.255510
11680.210.230.0/2380.210.230.1 to 80.210.231.25480.210.231.255510
11780.210.232.0/2380.210.232.1 to 80.210.233.25480.210.233.255510
11880.210.234.0/2380.210.234.1 to 80.210.235.25480.210.235.255510
11980.210.236.0/2380.210.236.1 to 80.210.237.25480.210.237.255510
12080.210.238.0/2380.210.238.1 to 80.210.239.25480.210.239.255510
12180.210.240.0/2380.210.240.1 to 80.210.241.25480.210.241.255510
12280.210.242.0/2380.210.242.1 to 80.210.243.25480.210.243.255510
12380.210.244.0/2380.210.244.1 to 80.210.245.25480.210.245.255510
12480.210.246.0/2380.210.246.1 to 80.210.247.25480.210.247.255510
12580.210.248.0/2380.210.248.1 to 80.210.249.25480.210.249.255510
12680.210.250.0/2380.210.250.1 to 80.210.251.25480.210.251.255510
12780.210.252.0/2380.210.252.1 to 80.210.253.25480.210.253.255510
12880.210.254.0/2380.210.254.1 to 80.210.255.25480.210.255.255510

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.