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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.

Network37.28.0.0/16
Usable hosts65,534
Subnet mask255.255.0.0
Addresses65,536
Network address
37.28.0.0
Broadcast address
37.28.255.255
First usable
37.28.0.1
Last usable
37.28.255.254
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 251C0000 · Integer 622592000 to 622657535
Reverse DNS zone
28.37.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00100101.00011100..00000000.0000000037.28.0.0
Subnet mask11111111.11111111..00000000.00000000255.255.0.0
Network00100101.00011100..00000000.0000000037.28.0.0
Broadcast00100101.00011100..11111111.1111111137.28.255.255
Split into smaller subnets/23

37.28.0.0/16 makes 128 subnets of /23.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
137.28.0.0/2337.28.0.1 to 37.28.1.25437.28.1.255510
237.28.2.0/2337.28.2.1 to 37.28.3.25437.28.3.255510
337.28.4.0/2337.28.4.1 to 37.28.5.25437.28.5.255510
437.28.6.0/2337.28.6.1 to 37.28.7.25437.28.7.255510
537.28.8.0/2337.28.8.1 to 37.28.9.25437.28.9.255510
637.28.10.0/2337.28.10.1 to 37.28.11.25437.28.11.255510
737.28.12.0/2337.28.12.1 to 37.28.13.25437.28.13.255510
837.28.14.0/2337.28.14.1 to 37.28.15.25437.28.15.255510
937.28.16.0/2337.28.16.1 to 37.28.17.25437.28.17.255510
1037.28.18.0/2337.28.18.1 to 37.28.19.25437.28.19.255510
1137.28.20.0/2337.28.20.1 to 37.28.21.25437.28.21.255510
1237.28.22.0/2337.28.22.1 to 37.28.23.25437.28.23.255510
1337.28.24.0/2337.28.24.1 to 37.28.25.25437.28.25.255510
1437.28.26.0/2337.28.26.1 to 37.28.27.25437.28.27.255510
1537.28.28.0/2337.28.28.1 to 37.28.29.25437.28.29.255510
1637.28.30.0/2337.28.30.1 to 37.28.31.25437.28.31.255510
1737.28.32.0/2337.28.32.1 to 37.28.33.25437.28.33.255510
1837.28.34.0/2337.28.34.1 to 37.28.35.25437.28.35.255510
1937.28.36.0/2337.28.36.1 to 37.28.37.25437.28.37.255510
2037.28.38.0/2337.28.38.1 to 37.28.39.25437.28.39.255510
2137.28.40.0/2337.28.40.1 to 37.28.41.25437.28.41.255510
2237.28.42.0/2337.28.42.1 to 37.28.43.25437.28.43.255510
2337.28.44.0/2337.28.44.1 to 37.28.45.25437.28.45.255510
2437.28.46.0/2337.28.46.1 to 37.28.47.25437.28.47.255510
2537.28.48.0/2337.28.48.1 to 37.28.49.25437.28.49.255510
2637.28.50.0/2337.28.50.1 to 37.28.51.25437.28.51.255510
2737.28.52.0/2337.28.52.1 to 37.28.53.25437.28.53.255510
2837.28.54.0/2337.28.54.1 to 37.28.55.25437.28.55.255510
2937.28.56.0/2337.28.56.1 to 37.28.57.25437.28.57.255510
3037.28.58.0/2337.28.58.1 to 37.28.59.25437.28.59.255510
3137.28.60.0/2337.28.60.1 to 37.28.61.25437.28.61.255510
3237.28.62.0/2337.28.62.1 to 37.28.63.25437.28.63.255510
3337.28.64.0/2337.28.64.1 to 37.28.65.25437.28.65.255510
3437.28.66.0/2337.28.66.1 to 37.28.67.25437.28.67.255510
3537.28.68.0/2337.28.68.1 to 37.28.69.25437.28.69.255510
3637.28.70.0/2337.28.70.1 to 37.28.71.25437.28.71.255510
3737.28.72.0/2337.28.72.1 to 37.28.73.25437.28.73.255510
3837.28.74.0/2337.28.74.1 to 37.28.75.25437.28.75.255510
3937.28.76.0/2337.28.76.1 to 37.28.77.25437.28.77.255510
4037.28.78.0/2337.28.78.1 to 37.28.79.25437.28.79.255510
4137.28.80.0/2337.28.80.1 to 37.28.81.25437.28.81.255510
4237.28.82.0/2337.28.82.1 to 37.28.83.25437.28.83.255510
4337.28.84.0/2337.28.84.1 to 37.28.85.25437.28.85.255510
4437.28.86.0/2337.28.86.1 to 37.28.87.25437.28.87.255510
4537.28.88.0/2337.28.88.1 to 37.28.89.25437.28.89.255510
4637.28.90.0/2337.28.90.1 to 37.28.91.25437.28.91.255510
4737.28.92.0/2337.28.92.1 to 37.28.93.25437.28.93.255510
4837.28.94.0/2337.28.94.1 to 37.28.95.25437.28.95.255510
4937.28.96.0/2337.28.96.1 to 37.28.97.25437.28.97.255510
5037.28.98.0/2337.28.98.1 to 37.28.99.25437.28.99.255510
5137.28.100.0/2337.28.100.1 to 37.28.101.25437.28.101.255510
5237.28.102.0/2337.28.102.1 to 37.28.103.25437.28.103.255510
5337.28.104.0/2337.28.104.1 to 37.28.105.25437.28.105.255510
5437.28.106.0/2337.28.106.1 to 37.28.107.25437.28.107.255510
5537.28.108.0/2337.28.108.1 to 37.28.109.25437.28.109.255510
5637.28.110.0/2337.28.110.1 to 37.28.111.25437.28.111.255510
5737.28.112.0/2337.28.112.1 to 37.28.113.25437.28.113.255510
5837.28.114.0/2337.28.114.1 to 37.28.115.25437.28.115.255510
5937.28.116.0/2337.28.116.1 to 37.28.117.25437.28.117.255510
6037.28.118.0/2337.28.118.1 to 37.28.119.25437.28.119.255510
6137.28.120.0/2337.28.120.1 to 37.28.121.25437.28.121.255510
6237.28.122.0/2337.28.122.1 to 37.28.123.25437.28.123.255510
6337.28.124.0/2337.28.124.1 to 37.28.125.25437.28.125.255510
6437.28.126.0/2337.28.126.1 to 37.28.127.25437.28.127.255510
6537.28.128.0/2337.28.128.1 to 37.28.129.25437.28.129.255510
6637.28.130.0/2337.28.130.1 to 37.28.131.25437.28.131.255510
6737.28.132.0/2337.28.132.1 to 37.28.133.25437.28.133.255510
6837.28.134.0/2337.28.134.1 to 37.28.135.25437.28.135.255510
6937.28.136.0/2337.28.136.1 to 37.28.137.25437.28.137.255510
7037.28.138.0/2337.28.138.1 to 37.28.139.25437.28.139.255510
7137.28.140.0/2337.28.140.1 to 37.28.141.25437.28.141.255510
7237.28.142.0/2337.28.142.1 to 37.28.143.25437.28.143.255510
7337.28.144.0/2337.28.144.1 to 37.28.145.25437.28.145.255510
7437.28.146.0/2337.28.146.1 to 37.28.147.25437.28.147.255510
7537.28.148.0/2337.28.148.1 to 37.28.149.25437.28.149.255510
7637.28.150.0/2337.28.150.1 to 37.28.151.25437.28.151.255510
7737.28.152.0/2337.28.152.1 to 37.28.153.25437.28.153.255510
7837.28.154.0/2337.28.154.1 to 37.28.155.25437.28.155.255510
7937.28.156.0/2337.28.156.1 to 37.28.157.25437.28.157.255510
8037.28.158.0/2337.28.158.1 to 37.28.159.25437.28.159.255510
8137.28.160.0/2337.28.160.1 to 37.28.161.25437.28.161.255510
8237.28.162.0/2337.28.162.1 to 37.28.163.25437.28.163.255510
8337.28.164.0/2337.28.164.1 to 37.28.165.25437.28.165.255510
8437.28.166.0/2337.28.166.1 to 37.28.167.25437.28.167.255510
8537.28.168.0/2337.28.168.1 to 37.28.169.25437.28.169.255510
8637.28.170.0/2337.28.170.1 to 37.28.171.25437.28.171.255510
8737.28.172.0/2337.28.172.1 to 37.28.173.25437.28.173.255510
8837.28.174.0/2337.28.174.1 to 37.28.175.25437.28.175.255510
8937.28.176.0/2337.28.176.1 to 37.28.177.25437.28.177.255510
9037.28.178.0/2337.28.178.1 to 37.28.179.25437.28.179.255510
9137.28.180.0/2337.28.180.1 to 37.28.181.25437.28.181.255510
9237.28.182.0/2337.28.182.1 to 37.28.183.25437.28.183.255510
9337.28.184.0/2337.28.184.1 to 37.28.185.25437.28.185.255510
9437.28.186.0/2337.28.186.1 to 37.28.187.25437.28.187.255510
9537.28.188.0/2337.28.188.1 to 37.28.189.25437.28.189.255510
9637.28.190.0/2337.28.190.1 to 37.28.191.25437.28.191.255510
9737.28.192.0/2337.28.192.1 to 37.28.193.25437.28.193.255510
9837.28.194.0/2337.28.194.1 to 37.28.195.25437.28.195.255510
9937.28.196.0/2337.28.196.1 to 37.28.197.25437.28.197.255510
10037.28.198.0/2337.28.198.1 to 37.28.199.25437.28.199.255510
10137.28.200.0/2337.28.200.1 to 37.28.201.25437.28.201.255510
10237.28.202.0/2337.28.202.1 to 37.28.203.25437.28.203.255510
10337.28.204.0/2337.28.204.1 to 37.28.205.25437.28.205.255510
10437.28.206.0/2337.28.206.1 to 37.28.207.25437.28.207.255510
10537.28.208.0/2337.28.208.1 to 37.28.209.25437.28.209.255510
10637.28.210.0/2337.28.210.1 to 37.28.211.25437.28.211.255510
10737.28.212.0/2337.28.212.1 to 37.28.213.25437.28.213.255510
10837.28.214.0/2337.28.214.1 to 37.28.215.25437.28.215.255510
10937.28.216.0/2337.28.216.1 to 37.28.217.25437.28.217.255510
11037.28.218.0/2337.28.218.1 to 37.28.219.25437.28.219.255510
11137.28.220.0/2337.28.220.1 to 37.28.221.25437.28.221.255510
11237.28.222.0/2337.28.222.1 to 37.28.223.25437.28.223.255510
11337.28.224.0/2337.28.224.1 to 37.28.225.25437.28.225.255510
11437.28.226.0/2337.28.226.1 to 37.28.227.25437.28.227.255510
11537.28.228.0/2337.28.228.1 to 37.28.229.25437.28.229.255510
11637.28.230.0/2337.28.230.1 to 37.28.231.25437.28.231.255510
11737.28.232.0/2337.28.232.1 to 37.28.233.25437.28.233.255510
11837.28.234.0/2337.28.234.1 to 37.28.235.25437.28.235.255510
11937.28.236.0/2337.28.236.1 to 37.28.237.25437.28.237.255510
12037.28.238.0/2337.28.238.1 to 37.28.239.25437.28.239.255510
12137.28.240.0/2337.28.240.1 to 37.28.241.25437.28.241.255510
12237.28.242.0/2337.28.242.1 to 37.28.243.25437.28.243.255510
12337.28.244.0/2337.28.244.1 to 37.28.245.25437.28.245.255510
12437.28.246.0/2337.28.246.1 to 37.28.247.25437.28.247.255510
12537.28.248.0/2337.28.248.1 to 37.28.249.25437.28.249.255510
12637.28.250.0/2337.28.250.1 to 37.28.251.25437.28.251.255510
12737.28.252.0/2337.28.252.1 to 37.28.253.25437.28.253.255510
12837.28.254.0/2337.28.254.1 to 37.28.255.25437.28.255.255510

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