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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.

Network20.89.0.0/16
Usable hosts65,534
Subnet mask255.255.0.0
Addresses65,536
Network address
20.89.0.0
Broadcast address
20.89.255.255
First usable
20.89.0.1
Last usable
20.89.255.254
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 14590000 · Integer 341377024 to 341442559
Reverse DNS zone
89.20.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00010100.01011001..00000000.0000000020.89.0.0
Subnet mask11111111.11111111..00000000.00000000255.255.0.0
Network00010100.01011001..00000000.0000000020.89.0.0
Broadcast00010100.01011001..11111111.1111111120.89.255.255
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)

20.89.0.0/16 makes 128 subnets of /23.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
120.89.0.0/2320.89.0.1 to 20.89.1.25420.89.1.255510
220.89.2.0/2320.89.2.1 to 20.89.3.25420.89.3.255510
320.89.4.0/2320.89.4.1 to 20.89.5.25420.89.5.255510
420.89.6.0/2320.89.6.1 to 20.89.7.25420.89.7.255510
520.89.8.0/2320.89.8.1 to 20.89.9.25420.89.9.255510
620.89.10.0/2320.89.10.1 to 20.89.11.25420.89.11.255510
720.89.12.0/2320.89.12.1 to 20.89.13.25420.89.13.255510
820.89.14.0/2320.89.14.1 to 20.89.15.25420.89.15.255510
920.89.16.0/2320.89.16.1 to 20.89.17.25420.89.17.255510
1020.89.18.0/2320.89.18.1 to 20.89.19.25420.89.19.255510
1120.89.20.0/2320.89.20.1 to 20.89.21.25420.89.21.255510
1220.89.22.0/2320.89.22.1 to 20.89.23.25420.89.23.255510
1320.89.24.0/2320.89.24.1 to 20.89.25.25420.89.25.255510
1420.89.26.0/2320.89.26.1 to 20.89.27.25420.89.27.255510
1520.89.28.0/2320.89.28.1 to 20.89.29.25420.89.29.255510
1620.89.30.0/2320.89.30.1 to 20.89.31.25420.89.31.255510
1720.89.32.0/2320.89.32.1 to 20.89.33.25420.89.33.255510
1820.89.34.0/2320.89.34.1 to 20.89.35.25420.89.35.255510
1920.89.36.0/2320.89.36.1 to 20.89.37.25420.89.37.255510
2020.89.38.0/2320.89.38.1 to 20.89.39.25420.89.39.255510
2120.89.40.0/2320.89.40.1 to 20.89.41.25420.89.41.255510
2220.89.42.0/2320.89.42.1 to 20.89.43.25420.89.43.255510
2320.89.44.0/2320.89.44.1 to 20.89.45.25420.89.45.255510
2420.89.46.0/2320.89.46.1 to 20.89.47.25420.89.47.255510
2520.89.48.0/2320.89.48.1 to 20.89.49.25420.89.49.255510
2620.89.50.0/2320.89.50.1 to 20.89.51.25420.89.51.255510
2720.89.52.0/2320.89.52.1 to 20.89.53.25420.89.53.255510
2820.89.54.0/2320.89.54.1 to 20.89.55.25420.89.55.255510
2920.89.56.0/2320.89.56.1 to 20.89.57.25420.89.57.255510
3020.89.58.0/2320.89.58.1 to 20.89.59.25420.89.59.255510
3120.89.60.0/2320.89.60.1 to 20.89.61.25420.89.61.255510
3220.89.62.0/2320.89.62.1 to 20.89.63.25420.89.63.255510
3320.89.64.0/2320.89.64.1 to 20.89.65.25420.89.65.255510
3420.89.66.0/2320.89.66.1 to 20.89.67.25420.89.67.255510
3520.89.68.0/2320.89.68.1 to 20.89.69.25420.89.69.255510
3620.89.70.0/2320.89.70.1 to 20.89.71.25420.89.71.255510
3720.89.72.0/2320.89.72.1 to 20.89.73.25420.89.73.255510
3820.89.74.0/2320.89.74.1 to 20.89.75.25420.89.75.255510
3920.89.76.0/2320.89.76.1 to 20.89.77.25420.89.77.255510
4020.89.78.0/2320.89.78.1 to 20.89.79.25420.89.79.255510
4120.89.80.0/2320.89.80.1 to 20.89.81.25420.89.81.255510
4220.89.82.0/2320.89.82.1 to 20.89.83.25420.89.83.255510
4320.89.84.0/2320.89.84.1 to 20.89.85.25420.89.85.255510
4420.89.86.0/2320.89.86.1 to 20.89.87.25420.89.87.255510
4520.89.88.0/2320.89.88.1 to 20.89.89.25420.89.89.255510
4620.89.90.0/2320.89.90.1 to 20.89.91.25420.89.91.255510
4720.89.92.0/2320.89.92.1 to 20.89.93.25420.89.93.255510
4820.89.94.0/2320.89.94.1 to 20.89.95.25420.89.95.255510
4920.89.96.0/2320.89.96.1 to 20.89.97.25420.89.97.255510
5020.89.98.0/2320.89.98.1 to 20.89.99.25420.89.99.255510
5120.89.100.0/2320.89.100.1 to 20.89.101.25420.89.101.255510
5220.89.102.0/2320.89.102.1 to 20.89.103.25420.89.103.255510
5320.89.104.0/2320.89.104.1 to 20.89.105.25420.89.105.255510
5420.89.106.0/2320.89.106.1 to 20.89.107.25420.89.107.255510
5520.89.108.0/2320.89.108.1 to 20.89.109.25420.89.109.255510
5620.89.110.0/2320.89.110.1 to 20.89.111.25420.89.111.255510
5720.89.112.0/2320.89.112.1 to 20.89.113.25420.89.113.255510
5820.89.114.0/2320.89.114.1 to 20.89.115.25420.89.115.255510
5920.89.116.0/2320.89.116.1 to 20.89.117.25420.89.117.255510
6020.89.118.0/2320.89.118.1 to 20.89.119.25420.89.119.255510
6120.89.120.0/2320.89.120.1 to 20.89.121.25420.89.121.255510
6220.89.122.0/2320.89.122.1 to 20.89.123.25420.89.123.255510
6320.89.124.0/2320.89.124.1 to 20.89.125.25420.89.125.255510
6420.89.126.0/2320.89.126.1 to 20.89.127.25420.89.127.255510
6520.89.128.0/2320.89.128.1 to 20.89.129.25420.89.129.255510
6620.89.130.0/2320.89.130.1 to 20.89.131.25420.89.131.255510
6720.89.132.0/2320.89.132.1 to 20.89.133.25420.89.133.255510
6820.89.134.0/2320.89.134.1 to 20.89.135.25420.89.135.255510
6920.89.136.0/2320.89.136.1 to 20.89.137.25420.89.137.255510
7020.89.138.0/2320.89.138.1 to 20.89.139.25420.89.139.255510
7120.89.140.0/2320.89.140.1 to 20.89.141.25420.89.141.255510
7220.89.142.0/2320.89.142.1 to 20.89.143.25420.89.143.255510
7320.89.144.0/2320.89.144.1 to 20.89.145.25420.89.145.255510
7420.89.146.0/2320.89.146.1 to 20.89.147.25420.89.147.255510
7520.89.148.0/2320.89.148.1 to 20.89.149.25420.89.149.255510
7620.89.150.0/2320.89.150.1 to 20.89.151.25420.89.151.255510
7720.89.152.0/2320.89.152.1 to 20.89.153.25420.89.153.255510
7820.89.154.0/2320.89.154.1 to 20.89.155.25420.89.155.255510
7920.89.156.0/2320.89.156.1 to 20.89.157.25420.89.157.255510
8020.89.158.0/2320.89.158.1 to 20.89.159.25420.89.159.255510
8120.89.160.0/2320.89.160.1 to 20.89.161.25420.89.161.255510
8220.89.162.0/2320.89.162.1 to 20.89.163.25420.89.163.255510
8320.89.164.0/2320.89.164.1 to 20.89.165.25420.89.165.255510
8420.89.166.0/2320.89.166.1 to 20.89.167.25420.89.167.255510
8520.89.168.0/2320.89.168.1 to 20.89.169.25420.89.169.255510
8620.89.170.0/2320.89.170.1 to 20.89.171.25420.89.171.255510
8720.89.172.0/2320.89.172.1 to 20.89.173.25420.89.173.255510
8820.89.174.0/2320.89.174.1 to 20.89.175.25420.89.175.255510
8920.89.176.0/2320.89.176.1 to 20.89.177.25420.89.177.255510
9020.89.178.0/2320.89.178.1 to 20.89.179.25420.89.179.255510
9120.89.180.0/2320.89.180.1 to 20.89.181.25420.89.181.255510
9220.89.182.0/2320.89.182.1 to 20.89.183.25420.89.183.255510
9320.89.184.0/2320.89.184.1 to 20.89.185.25420.89.185.255510
9420.89.186.0/2320.89.186.1 to 20.89.187.25420.89.187.255510
9520.89.188.0/2320.89.188.1 to 20.89.189.25420.89.189.255510
9620.89.190.0/2320.89.190.1 to 20.89.191.25420.89.191.255510
9720.89.192.0/2320.89.192.1 to 20.89.193.25420.89.193.255510
9820.89.194.0/2320.89.194.1 to 20.89.195.25420.89.195.255510
9920.89.196.0/2320.89.196.1 to 20.89.197.25420.89.197.255510
10020.89.198.0/2320.89.198.1 to 20.89.199.25420.89.199.255510
10120.89.200.0/2320.89.200.1 to 20.89.201.25420.89.201.255510
10220.89.202.0/2320.89.202.1 to 20.89.203.25420.89.203.255510
10320.89.204.0/2320.89.204.1 to 20.89.205.25420.89.205.255510
10420.89.206.0/2320.89.206.1 to 20.89.207.25420.89.207.255510
10520.89.208.0/2320.89.208.1 to 20.89.209.25420.89.209.255510
10620.89.210.0/2320.89.210.1 to 20.89.211.25420.89.211.255510
10720.89.212.0/2320.89.212.1 to 20.89.213.25420.89.213.255510
10820.89.214.0/2320.89.214.1 to 20.89.215.25420.89.215.255510
10920.89.216.0/2320.89.216.1 to 20.89.217.25420.89.217.255510
11020.89.218.0/2320.89.218.1 to 20.89.219.25420.89.219.255510
11120.89.220.0/2320.89.220.1 to 20.89.221.25420.89.221.255510
11220.89.222.0/2320.89.222.1 to 20.89.223.25420.89.223.255510
11320.89.224.0/2320.89.224.1 to 20.89.225.25420.89.225.255510
11420.89.226.0/2320.89.226.1 to 20.89.227.25420.89.227.255510
11520.89.228.0/2320.89.228.1 to 20.89.229.25420.89.229.255510
11620.89.230.0/2320.89.230.1 to 20.89.231.25420.89.231.255510
11720.89.232.0/2320.89.232.1 to 20.89.233.25420.89.233.255510
11820.89.234.0/2320.89.234.1 to 20.89.235.25420.89.235.255510
11920.89.236.0/2320.89.236.1 to 20.89.237.25420.89.237.255510
12020.89.238.0/2320.89.238.1 to 20.89.239.25420.89.239.255510
12120.89.240.0/2320.89.240.1 to 20.89.241.25420.89.241.255510
12220.89.242.0/2320.89.242.1 to 20.89.243.25420.89.243.255510
12320.89.244.0/2320.89.244.1 to 20.89.245.25420.89.245.255510
12420.89.246.0/2320.89.246.1 to 20.89.247.25420.89.247.255510
12520.89.248.0/2320.89.248.1 to 20.89.249.25420.89.249.255510
12620.89.250.0/2320.89.250.1 to 20.89.251.25420.89.251.255510
12720.89.252.0/2320.89.252.1 to 20.89.253.25420.89.253.255510
12820.89.254.0/2320.89.254.1 to 20.89.255.25420.89.255.255510

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.