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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.

Network13.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
13.0.0.0
Broadcast address
13.255.255.255
First usable
13.0.0.1
Last usable
13.255.255.254
Usable hosts
16,777,214 (16,777,216 less the network and broadcast addresses)
Subnet mask
255.0.0.0
Wildcard mask
0.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/8
Type
Public public
Old class
A (default /8)
As numbers
Hex 0D000000 · Integer 218103808 to 234881023
Reverse DNS zone
13.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00001101..00000000.00000000.0000000013.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network00001101..00000000.00000000.0000000013.0.0.0
Broadcast00001101..11111111.11111111.1111111113.255.255.255
Split into smaller subnets/15
/9 (2)/10 (4)/11 (8)/12 (16)/13 (32)/14 (64)/15 (128)/16 (256)/17 (512)/18 (1,024)/19 (2,048)/20 (4,096)

13.0.0.0/8 makes 128 subnets of /15.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
113.0.0.0/1513.0.0.1 to 13.1.255.25413.1.255.255131,070
213.2.0.0/1513.2.0.1 to 13.3.255.25413.3.255.255131,070
313.4.0.0/1513.4.0.1 to 13.5.255.25413.5.255.255131,070
413.6.0.0/1513.6.0.1 to 13.7.255.25413.7.255.255131,070
513.8.0.0/1513.8.0.1 to 13.9.255.25413.9.255.255131,070
613.10.0.0/1513.10.0.1 to 13.11.255.25413.11.255.255131,070
713.12.0.0/1513.12.0.1 to 13.13.255.25413.13.255.255131,070
813.14.0.0/1513.14.0.1 to 13.15.255.25413.15.255.255131,070
913.16.0.0/1513.16.0.1 to 13.17.255.25413.17.255.255131,070
1013.18.0.0/1513.18.0.1 to 13.19.255.25413.19.255.255131,070
1113.20.0.0/1513.20.0.1 to 13.21.255.25413.21.255.255131,070
1213.22.0.0/1513.22.0.1 to 13.23.255.25413.23.255.255131,070
1313.24.0.0/1513.24.0.1 to 13.25.255.25413.25.255.255131,070
1413.26.0.0/1513.26.0.1 to 13.27.255.25413.27.255.255131,070
1513.28.0.0/1513.28.0.1 to 13.29.255.25413.29.255.255131,070
1613.30.0.0/1513.30.0.1 to 13.31.255.25413.31.255.255131,070
1713.32.0.0/1513.32.0.1 to 13.33.255.25413.33.255.255131,070
1813.34.0.0/1513.34.0.1 to 13.35.255.25413.35.255.255131,070
1913.36.0.0/1513.36.0.1 to 13.37.255.25413.37.255.255131,070
2013.38.0.0/1513.38.0.1 to 13.39.255.25413.39.255.255131,070
2113.40.0.0/1513.40.0.1 to 13.41.255.25413.41.255.255131,070
2213.42.0.0/1513.42.0.1 to 13.43.255.25413.43.255.255131,070
2313.44.0.0/1513.44.0.1 to 13.45.255.25413.45.255.255131,070
2413.46.0.0/1513.46.0.1 to 13.47.255.25413.47.255.255131,070
2513.48.0.0/1513.48.0.1 to 13.49.255.25413.49.255.255131,070
2613.50.0.0/1513.50.0.1 to 13.51.255.25413.51.255.255131,070
2713.52.0.0/1513.52.0.1 to 13.53.255.25413.53.255.255131,070
2813.54.0.0/1513.54.0.1 to 13.55.255.25413.55.255.255131,070
2913.56.0.0/1513.56.0.1 to 13.57.255.25413.57.255.255131,070
3013.58.0.0/1513.58.0.1 to 13.59.255.25413.59.255.255131,070
3113.60.0.0/1513.60.0.1 to 13.61.255.25413.61.255.255131,070
3213.62.0.0/1513.62.0.1 to 13.63.255.25413.63.255.255131,070
3313.64.0.0/1513.64.0.1 to 13.65.255.25413.65.255.255131,070
3413.66.0.0/1513.66.0.1 to 13.67.255.25413.67.255.255131,070
3513.68.0.0/1513.68.0.1 to 13.69.255.25413.69.255.255131,070
3613.70.0.0/1513.70.0.1 to 13.71.255.25413.71.255.255131,070
3713.72.0.0/1513.72.0.1 to 13.73.255.25413.73.255.255131,070
3813.74.0.0/1513.74.0.1 to 13.75.255.25413.75.255.255131,070
3913.76.0.0/1513.76.0.1 to 13.77.255.25413.77.255.255131,070
4013.78.0.0/1513.78.0.1 to 13.79.255.25413.79.255.255131,070
4113.80.0.0/1513.80.0.1 to 13.81.255.25413.81.255.255131,070
4213.82.0.0/1513.82.0.1 to 13.83.255.25413.83.255.255131,070
4313.84.0.0/1513.84.0.1 to 13.85.255.25413.85.255.255131,070
4413.86.0.0/1513.86.0.1 to 13.87.255.25413.87.255.255131,070
4513.88.0.0/1513.88.0.1 to 13.89.255.25413.89.255.255131,070
4613.90.0.0/1513.90.0.1 to 13.91.255.25413.91.255.255131,070
4713.92.0.0/1513.92.0.1 to 13.93.255.25413.93.255.255131,070
4813.94.0.0/1513.94.0.1 to 13.95.255.25413.95.255.255131,070
4913.96.0.0/1513.96.0.1 to 13.97.255.25413.97.255.255131,070
5013.98.0.0/1513.98.0.1 to 13.99.255.25413.99.255.255131,070
5113.100.0.0/1513.100.0.1 to 13.101.255.25413.101.255.255131,070
5213.102.0.0/1513.102.0.1 to 13.103.255.25413.103.255.255131,070
5313.104.0.0/1513.104.0.1 to 13.105.255.25413.105.255.255131,070
5413.106.0.0/1513.106.0.1 to 13.107.255.25413.107.255.255131,070
5513.108.0.0/1513.108.0.1 to 13.109.255.25413.109.255.255131,070
5613.110.0.0/1513.110.0.1 to 13.111.255.25413.111.255.255131,070
5713.112.0.0/1513.112.0.1 to 13.113.255.25413.113.255.255131,070
5813.114.0.0/1513.114.0.1 to 13.115.255.25413.115.255.255131,070
5913.116.0.0/1513.116.0.1 to 13.117.255.25413.117.255.255131,070
6013.118.0.0/1513.118.0.1 to 13.119.255.25413.119.255.255131,070
6113.120.0.0/1513.120.0.1 to 13.121.255.25413.121.255.255131,070
6213.122.0.0/1513.122.0.1 to 13.123.255.25413.123.255.255131,070
6313.124.0.0/1513.124.0.1 to 13.125.255.25413.125.255.255131,070
6413.126.0.0/1513.126.0.1 to 13.127.255.25413.127.255.255131,070
6513.128.0.0/1513.128.0.1 to 13.129.255.25413.129.255.255131,070
6613.130.0.0/1513.130.0.1 to 13.131.255.25413.131.255.255131,070
6713.132.0.0/1513.132.0.1 to 13.133.255.25413.133.255.255131,070
6813.134.0.0/1513.134.0.1 to 13.135.255.25413.135.255.255131,070
6913.136.0.0/1513.136.0.1 to 13.137.255.25413.137.255.255131,070
7013.138.0.0/1513.138.0.1 to 13.139.255.25413.139.255.255131,070
7113.140.0.0/1513.140.0.1 to 13.141.255.25413.141.255.255131,070
7213.142.0.0/1513.142.0.1 to 13.143.255.25413.143.255.255131,070
7313.144.0.0/1513.144.0.1 to 13.145.255.25413.145.255.255131,070
7413.146.0.0/1513.146.0.1 to 13.147.255.25413.147.255.255131,070
7513.148.0.0/1513.148.0.1 to 13.149.255.25413.149.255.255131,070
7613.150.0.0/1513.150.0.1 to 13.151.255.25413.151.255.255131,070
7713.152.0.0/1513.152.0.1 to 13.153.255.25413.153.255.255131,070
7813.154.0.0/1513.154.0.1 to 13.155.255.25413.155.255.255131,070
7913.156.0.0/1513.156.0.1 to 13.157.255.25413.157.255.255131,070
8013.158.0.0/1513.158.0.1 to 13.159.255.25413.159.255.255131,070
8113.160.0.0/1513.160.0.1 to 13.161.255.25413.161.255.255131,070
8213.162.0.0/1513.162.0.1 to 13.163.255.25413.163.255.255131,070
8313.164.0.0/1513.164.0.1 to 13.165.255.25413.165.255.255131,070
8413.166.0.0/1513.166.0.1 to 13.167.255.25413.167.255.255131,070
8513.168.0.0/1513.168.0.1 to 13.169.255.25413.169.255.255131,070
8613.170.0.0/1513.170.0.1 to 13.171.255.25413.171.255.255131,070
8713.172.0.0/1513.172.0.1 to 13.173.255.25413.173.255.255131,070
8813.174.0.0/1513.174.0.1 to 13.175.255.25413.175.255.255131,070
8913.176.0.0/1513.176.0.1 to 13.177.255.25413.177.255.255131,070
9013.178.0.0/1513.178.0.1 to 13.179.255.25413.179.255.255131,070
9113.180.0.0/1513.180.0.1 to 13.181.255.25413.181.255.255131,070
9213.182.0.0/1513.182.0.1 to 13.183.255.25413.183.255.255131,070
9313.184.0.0/1513.184.0.1 to 13.185.255.25413.185.255.255131,070
9413.186.0.0/1513.186.0.1 to 13.187.255.25413.187.255.255131,070
9513.188.0.0/1513.188.0.1 to 13.189.255.25413.189.255.255131,070
9613.190.0.0/1513.190.0.1 to 13.191.255.25413.191.255.255131,070
9713.192.0.0/1513.192.0.1 to 13.193.255.25413.193.255.255131,070
9813.194.0.0/1513.194.0.1 to 13.195.255.25413.195.255.255131,070
9913.196.0.0/1513.196.0.1 to 13.197.255.25413.197.255.255131,070
10013.198.0.0/1513.198.0.1 to 13.199.255.25413.199.255.255131,070
10113.200.0.0/1513.200.0.1 to 13.201.255.25413.201.255.255131,070
10213.202.0.0/1513.202.0.1 to 13.203.255.25413.203.255.255131,070
10313.204.0.0/1513.204.0.1 to 13.205.255.25413.205.255.255131,070
10413.206.0.0/1513.206.0.1 to 13.207.255.25413.207.255.255131,070
10513.208.0.0/1513.208.0.1 to 13.209.255.25413.209.255.255131,070
10613.210.0.0/1513.210.0.1 to 13.211.255.25413.211.255.255131,070
10713.212.0.0/1513.212.0.1 to 13.213.255.25413.213.255.255131,070
10813.214.0.0/1513.214.0.1 to 13.215.255.25413.215.255.255131,070
10913.216.0.0/1513.216.0.1 to 13.217.255.25413.217.255.255131,070
11013.218.0.0/1513.218.0.1 to 13.219.255.25413.219.255.255131,070
11113.220.0.0/1513.220.0.1 to 13.221.255.25413.221.255.255131,070
11213.222.0.0/1513.222.0.1 to 13.223.255.25413.223.255.255131,070
11313.224.0.0/1513.224.0.1 to 13.225.255.25413.225.255.255131,070
11413.226.0.0/1513.226.0.1 to 13.227.255.25413.227.255.255131,070
11513.228.0.0/1513.228.0.1 to 13.229.255.25413.229.255.255131,070
11613.230.0.0/1513.230.0.1 to 13.231.255.25413.231.255.255131,070
11713.232.0.0/1513.232.0.1 to 13.233.255.25413.233.255.255131,070
11813.234.0.0/1513.234.0.1 to 13.235.255.25413.235.255.255131,070
11913.236.0.0/1513.236.0.1 to 13.237.255.25413.237.255.255131,070
12013.238.0.0/1513.238.0.1 to 13.239.255.25413.239.255.255131,070
12113.240.0.0/1513.240.0.1 to 13.241.255.25413.241.255.255131,070
12213.242.0.0/1513.242.0.1 to 13.243.255.25413.243.255.255131,070
12313.244.0.0/1513.244.0.1 to 13.245.255.25413.245.255.255131,070
12413.246.0.0/1513.246.0.1 to 13.247.255.25413.247.255.255131,070
12513.248.0.0/1513.248.0.1 to 13.249.255.25413.249.255.255131,070
12613.250.0.0/1513.250.0.1 to 13.251.255.25413.251.255.255131,070
12713.252.0.0/1513.252.0.1 to 13.253.255.25413.253.255.255131,070
12813.254.0.0/1513.254.0.1 to 13.255.255.25413.255.255.255131,070

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.