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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.

Network57.131.0.0/16
Usable hosts65,534
Subnet mask255.255.0.0
Addresses65,536
Network address
57.131.0.0
Broadcast address
57.131.255.255
First usable
57.131.0.1
Last usable
57.131.255.254
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 39830000 · Integer 964886528 to 964952063
Reverse DNS zone
131.57.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00111001.10000011..00000000.0000000057.131.0.0
Subnet mask11111111.11111111..00000000.00000000255.255.0.0
Network00111001.10000011..00000000.0000000057.131.0.0
Broadcast00111001.10000011..11111111.1111111157.131.255.255
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)

57.131.0.0/16 makes 128 subnets of /23.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
157.131.0.0/2357.131.0.1 to 57.131.1.25457.131.1.255510
257.131.2.0/2357.131.2.1 to 57.131.3.25457.131.3.255510
357.131.4.0/2357.131.4.1 to 57.131.5.25457.131.5.255510
457.131.6.0/2357.131.6.1 to 57.131.7.25457.131.7.255510
557.131.8.0/2357.131.8.1 to 57.131.9.25457.131.9.255510
657.131.10.0/2357.131.10.1 to 57.131.11.25457.131.11.255510
757.131.12.0/2357.131.12.1 to 57.131.13.25457.131.13.255510
857.131.14.0/2357.131.14.1 to 57.131.15.25457.131.15.255510
957.131.16.0/2357.131.16.1 to 57.131.17.25457.131.17.255510
1057.131.18.0/2357.131.18.1 to 57.131.19.25457.131.19.255510
1157.131.20.0/2357.131.20.1 to 57.131.21.25457.131.21.255510
1257.131.22.0/2357.131.22.1 to 57.131.23.25457.131.23.255510
1357.131.24.0/2357.131.24.1 to 57.131.25.25457.131.25.255510
1457.131.26.0/2357.131.26.1 to 57.131.27.25457.131.27.255510
1557.131.28.0/2357.131.28.1 to 57.131.29.25457.131.29.255510
1657.131.30.0/2357.131.30.1 to 57.131.31.25457.131.31.255510
1757.131.32.0/2357.131.32.1 to 57.131.33.25457.131.33.255510
1857.131.34.0/2357.131.34.1 to 57.131.35.25457.131.35.255510
1957.131.36.0/2357.131.36.1 to 57.131.37.25457.131.37.255510
2057.131.38.0/2357.131.38.1 to 57.131.39.25457.131.39.255510
2157.131.40.0/2357.131.40.1 to 57.131.41.25457.131.41.255510
2257.131.42.0/2357.131.42.1 to 57.131.43.25457.131.43.255510
2357.131.44.0/2357.131.44.1 to 57.131.45.25457.131.45.255510
2457.131.46.0/2357.131.46.1 to 57.131.47.25457.131.47.255510
2557.131.48.0/2357.131.48.1 to 57.131.49.25457.131.49.255510
2657.131.50.0/2357.131.50.1 to 57.131.51.25457.131.51.255510
2757.131.52.0/2357.131.52.1 to 57.131.53.25457.131.53.255510
2857.131.54.0/2357.131.54.1 to 57.131.55.25457.131.55.255510
2957.131.56.0/2357.131.56.1 to 57.131.57.25457.131.57.255510
3057.131.58.0/2357.131.58.1 to 57.131.59.25457.131.59.255510
3157.131.60.0/2357.131.60.1 to 57.131.61.25457.131.61.255510
3257.131.62.0/2357.131.62.1 to 57.131.63.25457.131.63.255510
3357.131.64.0/2357.131.64.1 to 57.131.65.25457.131.65.255510
3457.131.66.0/2357.131.66.1 to 57.131.67.25457.131.67.255510
3557.131.68.0/2357.131.68.1 to 57.131.69.25457.131.69.255510
3657.131.70.0/2357.131.70.1 to 57.131.71.25457.131.71.255510
3757.131.72.0/2357.131.72.1 to 57.131.73.25457.131.73.255510
3857.131.74.0/2357.131.74.1 to 57.131.75.25457.131.75.255510
3957.131.76.0/2357.131.76.1 to 57.131.77.25457.131.77.255510
4057.131.78.0/2357.131.78.1 to 57.131.79.25457.131.79.255510
4157.131.80.0/2357.131.80.1 to 57.131.81.25457.131.81.255510
4257.131.82.0/2357.131.82.1 to 57.131.83.25457.131.83.255510
4357.131.84.0/2357.131.84.1 to 57.131.85.25457.131.85.255510
4457.131.86.0/2357.131.86.1 to 57.131.87.25457.131.87.255510
4557.131.88.0/2357.131.88.1 to 57.131.89.25457.131.89.255510
4657.131.90.0/2357.131.90.1 to 57.131.91.25457.131.91.255510
4757.131.92.0/2357.131.92.1 to 57.131.93.25457.131.93.255510
4857.131.94.0/2357.131.94.1 to 57.131.95.25457.131.95.255510
4957.131.96.0/2357.131.96.1 to 57.131.97.25457.131.97.255510
5057.131.98.0/2357.131.98.1 to 57.131.99.25457.131.99.255510
5157.131.100.0/2357.131.100.1 to 57.131.101.25457.131.101.255510
5257.131.102.0/2357.131.102.1 to 57.131.103.25457.131.103.255510
5357.131.104.0/2357.131.104.1 to 57.131.105.25457.131.105.255510
5457.131.106.0/2357.131.106.1 to 57.131.107.25457.131.107.255510
5557.131.108.0/2357.131.108.1 to 57.131.109.25457.131.109.255510
5657.131.110.0/2357.131.110.1 to 57.131.111.25457.131.111.255510
5757.131.112.0/2357.131.112.1 to 57.131.113.25457.131.113.255510
5857.131.114.0/2357.131.114.1 to 57.131.115.25457.131.115.255510
5957.131.116.0/2357.131.116.1 to 57.131.117.25457.131.117.255510
6057.131.118.0/2357.131.118.1 to 57.131.119.25457.131.119.255510
6157.131.120.0/2357.131.120.1 to 57.131.121.25457.131.121.255510
6257.131.122.0/2357.131.122.1 to 57.131.123.25457.131.123.255510
6357.131.124.0/2357.131.124.1 to 57.131.125.25457.131.125.255510
6457.131.126.0/2357.131.126.1 to 57.131.127.25457.131.127.255510
6557.131.128.0/2357.131.128.1 to 57.131.129.25457.131.129.255510
6657.131.130.0/2357.131.130.1 to 57.131.131.25457.131.131.255510
6757.131.132.0/2357.131.132.1 to 57.131.133.25457.131.133.255510
6857.131.134.0/2357.131.134.1 to 57.131.135.25457.131.135.255510
6957.131.136.0/2357.131.136.1 to 57.131.137.25457.131.137.255510
7057.131.138.0/2357.131.138.1 to 57.131.139.25457.131.139.255510
7157.131.140.0/2357.131.140.1 to 57.131.141.25457.131.141.255510
7257.131.142.0/2357.131.142.1 to 57.131.143.25457.131.143.255510
7357.131.144.0/2357.131.144.1 to 57.131.145.25457.131.145.255510
7457.131.146.0/2357.131.146.1 to 57.131.147.25457.131.147.255510
7557.131.148.0/2357.131.148.1 to 57.131.149.25457.131.149.255510
7657.131.150.0/2357.131.150.1 to 57.131.151.25457.131.151.255510
7757.131.152.0/2357.131.152.1 to 57.131.153.25457.131.153.255510
7857.131.154.0/2357.131.154.1 to 57.131.155.25457.131.155.255510
7957.131.156.0/2357.131.156.1 to 57.131.157.25457.131.157.255510
8057.131.158.0/2357.131.158.1 to 57.131.159.25457.131.159.255510
8157.131.160.0/2357.131.160.1 to 57.131.161.25457.131.161.255510
8257.131.162.0/2357.131.162.1 to 57.131.163.25457.131.163.255510
8357.131.164.0/2357.131.164.1 to 57.131.165.25457.131.165.255510
8457.131.166.0/2357.131.166.1 to 57.131.167.25457.131.167.255510
8557.131.168.0/2357.131.168.1 to 57.131.169.25457.131.169.255510
8657.131.170.0/2357.131.170.1 to 57.131.171.25457.131.171.255510
8757.131.172.0/2357.131.172.1 to 57.131.173.25457.131.173.255510
8857.131.174.0/2357.131.174.1 to 57.131.175.25457.131.175.255510
8957.131.176.0/2357.131.176.1 to 57.131.177.25457.131.177.255510
9057.131.178.0/2357.131.178.1 to 57.131.179.25457.131.179.255510
9157.131.180.0/2357.131.180.1 to 57.131.181.25457.131.181.255510
9257.131.182.0/2357.131.182.1 to 57.131.183.25457.131.183.255510
9357.131.184.0/2357.131.184.1 to 57.131.185.25457.131.185.255510
9457.131.186.0/2357.131.186.1 to 57.131.187.25457.131.187.255510
9557.131.188.0/2357.131.188.1 to 57.131.189.25457.131.189.255510
9657.131.190.0/2357.131.190.1 to 57.131.191.25457.131.191.255510
9757.131.192.0/2357.131.192.1 to 57.131.193.25457.131.193.255510
9857.131.194.0/2357.131.194.1 to 57.131.195.25457.131.195.255510
9957.131.196.0/2357.131.196.1 to 57.131.197.25457.131.197.255510
10057.131.198.0/2357.131.198.1 to 57.131.199.25457.131.199.255510
10157.131.200.0/2357.131.200.1 to 57.131.201.25457.131.201.255510
10257.131.202.0/2357.131.202.1 to 57.131.203.25457.131.203.255510
10357.131.204.0/2357.131.204.1 to 57.131.205.25457.131.205.255510
10457.131.206.0/2357.131.206.1 to 57.131.207.25457.131.207.255510
10557.131.208.0/2357.131.208.1 to 57.131.209.25457.131.209.255510
10657.131.210.0/2357.131.210.1 to 57.131.211.25457.131.211.255510
10757.131.212.0/2357.131.212.1 to 57.131.213.25457.131.213.255510
10857.131.214.0/2357.131.214.1 to 57.131.215.25457.131.215.255510
10957.131.216.0/2357.131.216.1 to 57.131.217.25457.131.217.255510
11057.131.218.0/2357.131.218.1 to 57.131.219.25457.131.219.255510
11157.131.220.0/2357.131.220.1 to 57.131.221.25457.131.221.255510
11257.131.222.0/2357.131.222.1 to 57.131.223.25457.131.223.255510
11357.131.224.0/2357.131.224.1 to 57.131.225.25457.131.225.255510
11457.131.226.0/2357.131.226.1 to 57.131.227.25457.131.227.255510
11557.131.228.0/2357.131.228.1 to 57.131.229.25457.131.229.255510
11657.131.230.0/2357.131.230.1 to 57.131.231.25457.131.231.255510
11757.131.232.0/2357.131.232.1 to 57.131.233.25457.131.233.255510
11857.131.234.0/2357.131.234.1 to 57.131.235.25457.131.235.255510
11957.131.236.0/2357.131.236.1 to 57.131.237.25457.131.237.255510
12057.131.238.0/2357.131.238.1 to 57.131.239.25457.131.239.255510
12157.131.240.0/2357.131.240.1 to 57.131.241.25457.131.241.255510
12257.131.242.0/2357.131.242.1 to 57.131.243.25457.131.243.255510
12357.131.244.0/2357.131.244.1 to 57.131.245.25457.131.245.255510
12457.131.246.0/2357.131.246.1 to 57.131.247.25457.131.247.255510
12557.131.248.0/2357.131.248.1 to 57.131.249.25457.131.249.255510
12657.131.250.0/2357.131.250.1 to 57.131.251.25457.131.251.255510
12757.131.252.0/2357.131.252.1 to 57.131.253.25457.131.253.255510
12857.131.254.0/2357.131.254.1 to 57.131.255.25457.131.255.255510

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.