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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.

Network96.232.0.0/15
Usable hosts131,070
Subnet mask255.254.0.0
Addresses131,072
Network address
96.232.0.0
Broadcast address
96.233.255.255
First usable
96.232.0.1
Last usable
96.233.255.254
Usable hosts
131,070 (131,072 less the network and broadcast addresses)
Subnet mask
255.254.0.0
Wildcard mask
0.1.255.255 (Cisco ACLs, OSPF)
Prefix length
/15
Type
Public public
Old class
A (default /8)
As numbers
Hex 60E80000 · Integer 1625817088 to 1625948159
Reverse DNS zones
232.96.in-addr.arpa
233.96.in-addr.arpa
/15 is not on a 8-bit boundary, so it takes 2 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01100000.11101000.00000000.0000000096.232.0.0
Subnet mask11111111.11111110.00000000.00000000255.254.0.0
Network01100000.11101000.00000000.0000000096.232.0.0
Broadcast01100000.11101001.11111111.1111111196.233.255.255
Split into smaller subnets/21
/16 (2)/17 (4)/18 (8)/19 (16)/20 (32)/21 (64)/22 (128)/23 (256)/24 (512)/25 (1,024)/26 (2,048)/27 (4,096)

96.232.0.0/15 makes 64 subnets of /21.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
196.232.0.0/2196.232.0.1 to 96.232.7.25496.232.7.2552,046
296.232.8.0/2196.232.8.1 to 96.232.15.25496.232.15.2552,046
396.232.16.0/2196.232.16.1 to 96.232.23.25496.232.23.2552,046
496.232.24.0/2196.232.24.1 to 96.232.31.25496.232.31.2552,046
596.232.32.0/2196.232.32.1 to 96.232.39.25496.232.39.2552,046
696.232.40.0/2196.232.40.1 to 96.232.47.25496.232.47.2552,046
796.232.48.0/2196.232.48.1 to 96.232.55.25496.232.55.2552,046
896.232.56.0/2196.232.56.1 to 96.232.63.25496.232.63.2552,046
996.232.64.0/2196.232.64.1 to 96.232.71.25496.232.71.2552,046
1096.232.72.0/2196.232.72.1 to 96.232.79.25496.232.79.2552,046
1196.232.80.0/2196.232.80.1 to 96.232.87.25496.232.87.2552,046
1296.232.88.0/2196.232.88.1 to 96.232.95.25496.232.95.2552,046
1396.232.96.0/2196.232.96.1 to 96.232.103.25496.232.103.2552,046
1496.232.104.0/2196.232.104.1 to 96.232.111.25496.232.111.2552,046
1596.232.112.0/2196.232.112.1 to 96.232.119.25496.232.119.2552,046
1696.232.120.0/2196.232.120.1 to 96.232.127.25496.232.127.2552,046
1796.232.128.0/2196.232.128.1 to 96.232.135.25496.232.135.2552,046
1896.232.136.0/2196.232.136.1 to 96.232.143.25496.232.143.2552,046
1996.232.144.0/2196.232.144.1 to 96.232.151.25496.232.151.2552,046
2096.232.152.0/2196.232.152.1 to 96.232.159.25496.232.159.2552,046
2196.232.160.0/2196.232.160.1 to 96.232.167.25496.232.167.2552,046
2296.232.168.0/2196.232.168.1 to 96.232.175.25496.232.175.2552,046
2396.232.176.0/2196.232.176.1 to 96.232.183.25496.232.183.2552,046
2496.232.184.0/2196.232.184.1 to 96.232.191.25496.232.191.2552,046
2596.232.192.0/2196.232.192.1 to 96.232.199.25496.232.199.2552,046
2696.232.200.0/2196.232.200.1 to 96.232.207.25496.232.207.2552,046
2796.232.208.0/2196.232.208.1 to 96.232.215.25496.232.215.2552,046
2896.232.216.0/2196.232.216.1 to 96.232.223.25496.232.223.2552,046
2996.232.224.0/2196.232.224.1 to 96.232.231.25496.232.231.2552,046
3096.232.232.0/2196.232.232.1 to 96.232.239.25496.232.239.2552,046
3196.232.240.0/2196.232.240.1 to 96.232.247.25496.232.247.2552,046
3296.232.248.0/2196.232.248.1 to 96.232.255.25496.232.255.2552,046
3396.233.0.0/2196.233.0.1 to 96.233.7.25496.233.7.2552,046
3496.233.8.0/2196.233.8.1 to 96.233.15.25496.233.15.2552,046
3596.233.16.0/2196.233.16.1 to 96.233.23.25496.233.23.2552,046
3696.233.24.0/2196.233.24.1 to 96.233.31.25496.233.31.2552,046
3796.233.32.0/2196.233.32.1 to 96.233.39.25496.233.39.2552,046
3896.233.40.0/2196.233.40.1 to 96.233.47.25496.233.47.2552,046
3996.233.48.0/2196.233.48.1 to 96.233.55.25496.233.55.2552,046
4096.233.56.0/2196.233.56.1 to 96.233.63.25496.233.63.2552,046
4196.233.64.0/2196.233.64.1 to 96.233.71.25496.233.71.2552,046
4296.233.72.0/2196.233.72.1 to 96.233.79.25496.233.79.2552,046
4396.233.80.0/2196.233.80.1 to 96.233.87.25496.233.87.2552,046
4496.233.88.0/2196.233.88.1 to 96.233.95.25496.233.95.2552,046
4596.233.96.0/2196.233.96.1 to 96.233.103.25496.233.103.2552,046
4696.233.104.0/2196.233.104.1 to 96.233.111.25496.233.111.2552,046
4796.233.112.0/2196.233.112.1 to 96.233.119.25496.233.119.2552,046
4896.233.120.0/2196.233.120.1 to 96.233.127.25496.233.127.2552,046
4996.233.128.0/2196.233.128.1 to 96.233.135.25496.233.135.2552,046
5096.233.136.0/2196.233.136.1 to 96.233.143.25496.233.143.2552,046
5196.233.144.0/2196.233.144.1 to 96.233.151.25496.233.151.2552,046
5296.233.152.0/2196.233.152.1 to 96.233.159.25496.233.159.2552,046
5396.233.160.0/2196.233.160.1 to 96.233.167.25496.233.167.2552,046
5496.233.168.0/2196.233.168.1 to 96.233.175.25496.233.175.2552,046
5596.233.176.0/2196.233.176.1 to 96.233.183.25496.233.183.2552,046
5696.233.184.0/2196.233.184.1 to 96.233.191.25496.233.191.2552,046
5796.233.192.0/2196.233.192.1 to 96.233.199.25496.233.199.2552,046
5896.233.200.0/2196.233.200.1 to 96.233.207.25496.233.207.2552,046
5996.233.208.0/2196.233.208.1 to 96.233.215.25496.233.215.2552,046
6096.233.216.0/2196.233.216.1 to 96.233.223.25496.233.223.2552,046
6196.233.224.0/2196.233.224.1 to 96.233.231.25496.233.231.2552,046
6296.233.232.0/2196.233.232.1 to 96.233.239.25496.233.239.2552,046
6396.233.240.0/2196.233.240.1 to 96.233.247.25496.233.247.2552,046
6496.233.248.0/2196.233.248.1 to 96.233.255.25496.233.255.2552,046

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.