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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.

Network17.72.0.0/14
Usable hosts262,142
Subnet mask255.252.0.0
Addresses262,144
Network address
17.72.0.0
Broadcast address
17.75.255.255
First usable
17.72.0.1
Last usable
17.75.255.254
Usable hosts
262,142 (262,144 less the network and broadcast addresses)
Subnet mask
255.252.0.0
Wildcard mask
0.3.255.255 (Cisco ACLs, OSPF)
Prefix length
/14
Type
Public public
Old class
A (default /8)
As numbers
Hex 11480000 · Integer 289931264 to 290193407
Reverse DNS zones
72.17.in-addr.arpa
73.17.in-addr.arpa
74.17.in-addr.arpa
75.17.in-addr.arpa
/14 is not on a 8-bit boundary, so it takes 4 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00010001.01001000.00000000.0000000017.72.0.0
Subnet mask11111111.11111100.00000000.00000000255.252.0.0
Network00010001.01001000.00000000.0000000017.72.0.0
Broadcast00010001.01001011.11111111.1111111117.75.255.255
Split into smaller subnets/20
/15 (2)/16 (4)/17 (8)/18 (16)/19 (32)/20 (64)/21 (128)/22 (256)/23 (512)/24 (1,024)/25 (2,048)/26 (4,096)

17.72.0.0/14 makes 64 subnets of /20.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
117.72.0.0/2017.72.0.1 to 17.72.15.25417.72.15.2554,094
217.72.16.0/2017.72.16.1 to 17.72.31.25417.72.31.2554,094
317.72.32.0/2017.72.32.1 to 17.72.47.25417.72.47.2554,094
417.72.48.0/2017.72.48.1 to 17.72.63.25417.72.63.2554,094
517.72.64.0/2017.72.64.1 to 17.72.79.25417.72.79.2554,094
617.72.80.0/2017.72.80.1 to 17.72.95.25417.72.95.2554,094
717.72.96.0/2017.72.96.1 to 17.72.111.25417.72.111.2554,094
817.72.112.0/2017.72.112.1 to 17.72.127.25417.72.127.2554,094
917.72.128.0/2017.72.128.1 to 17.72.143.25417.72.143.2554,094
1017.72.144.0/2017.72.144.1 to 17.72.159.25417.72.159.2554,094
1117.72.160.0/2017.72.160.1 to 17.72.175.25417.72.175.2554,094
1217.72.176.0/2017.72.176.1 to 17.72.191.25417.72.191.2554,094
1317.72.192.0/2017.72.192.1 to 17.72.207.25417.72.207.2554,094
1417.72.208.0/2017.72.208.1 to 17.72.223.25417.72.223.2554,094
1517.72.224.0/2017.72.224.1 to 17.72.239.25417.72.239.2554,094
1617.72.240.0/2017.72.240.1 to 17.72.255.25417.72.255.2554,094
1717.73.0.0/2017.73.0.1 to 17.73.15.25417.73.15.2554,094
1817.73.16.0/2017.73.16.1 to 17.73.31.25417.73.31.2554,094
1917.73.32.0/2017.73.32.1 to 17.73.47.25417.73.47.2554,094
2017.73.48.0/2017.73.48.1 to 17.73.63.25417.73.63.2554,094
2117.73.64.0/2017.73.64.1 to 17.73.79.25417.73.79.2554,094
2217.73.80.0/2017.73.80.1 to 17.73.95.25417.73.95.2554,094
2317.73.96.0/2017.73.96.1 to 17.73.111.25417.73.111.2554,094
2417.73.112.0/2017.73.112.1 to 17.73.127.25417.73.127.2554,094
2517.73.128.0/2017.73.128.1 to 17.73.143.25417.73.143.2554,094
2617.73.144.0/2017.73.144.1 to 17.73.159.25417.73.159.2554,094
2717.73.160.0/2017.73.160.1 to 17.73.175.25417.73.175.2554,094
2817.73.176.0/2017.73.176.1 to 17.73.191.25417.73.191.2554,094
2917.73.192.0/2017.73.192.1 to 17.73.207.25417.73.207.2554,094
3017.73.208.0/2017.73.208.1 to 17.73.223.25417.73.223.2554,094
3117.73.224.0/2017.73.224.1 to 17.73.239.25417.73.239.2554,094
3217.73.240.0/2017.73.240.1 to 17.73.255.25417.73.255.2554,094
3317.74.0.0/2017.74.0.1 to 17.74.15.25417.74.15.2554,094
3417.74.16.0/2017.74.16.1 to 17.74.31.25417.74.31.2554,094
3517.74.32.0/2017.74.32.1 to 17.74.47.25417.74.47.2554,094
3617.74.48.0/2017.74.48.1 to 17.74.63.25417.74.63.2554,094
3717.74.64.0/2017.74.64.1 to 17.74.79.25417.74.79.2554,094
3817.74.80.0/2017.74.80.1 to 17.74.95.25417.74.95.2554,094
3917.74.96.0/2017.74.96.1 to 17.74.111.25417.74.111.2554,094
4017.74.112.0/2017.74.112.1 to 17.74.127.25417.74.127.2554,094
4117.74.128.0/2017.74.128.1 to 17.74.143.25417.74.143.2554,094
4217.74.144.0/2017.74.144.1 to 17.74.159.25417.74.159.2554,094
4317.74.160.0/2017.74.160.1 to 17.74.175.25417.74.175.2554,094
4417.74.176.0/2017.74.176.1 to 17.74.191.25417.74.191.2554,094
4517.74.192.0/2017.74.192.1 to 17.74.207.25417.74.207.2554,094
4617.74.208.0/2017.74.208.1 to 17.74.223.25417.74.223.2554,094
4717.74.224.0/2017.74.224.1 to 17.74.239.25417.74.239.2554,094
4817.74.240.0/2017.74.240.1 to 17.74.255.25417.74.255.2554,094
4917.75.0.0/2017.75.0.1 to 17.75.15.25417.75.15.2554,094
5017.75.16.0/2017.75.16.1 to 17.75.31.25417.75.31.2554,094
5117.75.32.0/2017.75.32.1 to 17.75.47.25417.75.47.2554,094
5217.75.48.0/2017.75.48.1 to 17.75.63.25417.75.63.2554,094
5317.75.64.0/2017.75.64.1 to 17.75.79.25417.75.79.2554,094
5417.75.80.0/2017.75.80.1 to 17.75.95.25417.75.95.2554,094
5517.75.96.0/2017.75.96.1 to 17.75.111.25417.75.111.2554,094
5617.75.112.0/2017.75.112.1 to 17.75.127.25417.75.127.2554,094
5717.75.128.0/2017.75.128.1 to 17.75.143.25417.75.143.2554,094
5817.75.144.0/2017.75.144.1 to 17.75.159.25417.75.159.2554,094
5917.75.160.0/2017.75.160.1 to 17.75.175.25417.75.175.2554,094
6017.75.176.0/2017.75.176.1 to 17.75.191.25417.75.191.2554,094
6117.75.192.0/2017.75.192.1 to 17.75.207.25417.75.207.2554,094
6217.75.208.0/2017.75.208.1 to 17.75.223.25417.75.223.2554,094
6317.75.224.0/2017.75.224.1 to 17.75.239.25417.75.239.2554,094
6417.75.240.0/2017.75.240.1 to 17.75.255.25417.75.255.2554,094

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.