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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.

Network27.232.0.0/15
Usable hosts131,070
Subnet mask255.254.0.0
Addresses131,072
Network address
27.232.0.0
Broadcast address
27.233.255.255
First usable
27.232.0.1
Last usable
27.233.255.254
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 1BE80000 · Integer 468189184 to 468320255
Reverse DNS zones
232.27.in-addr.arpa
233.27.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
Address00011011.11101000.00000000.0000000027.232.0.0
Subnet mask11111111.11111110.00000000.00000000255.254.0.0
Network00011011.11101000.00000000.0000000027.232.0.0
Broadcast00011011.11101001.11111111.1111111127.233.255.255
Split into smaller subnets/22
/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)

27.232.0.0/15 makes 128 subnets of /22.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
127.232.0.0/2227.232.0.1 to 27.232.3.25427.232.3.2551,022
227.232.4.0/2227.232.4.1 to 27.232.7.25427.232.7.2551,022
327.232.8.0/2227.232.8.1 to 27.232.11.25427.232.11.2551,022
427.232.12.0/2227.232.12.1 to 27.232.15.25427.232.15.2551,022
527.232.16.0/2227.232.16.1 to 27.232.19.25427.232.19.2551,022
627.232.20.0/2227.232.20.1 to 27.232.23.25427.232.23.2551,022
727.232.24.0/2227.232.24.1 to 27.232.27.25427.232.27.2551,022
827.232.28.0/2227.232.28.1 to 27.232.31.25427.232.31.2551,022
927.232.32.0/2227.232.32.1 to 27.232.35.25427.232.35.2551,022
1027.232.36.0/2227.232.36.1 to 27.232.39.25427.232.39.2551,022
1127.232.40.0/2227.232.40.1 to 27.232.43.25427.232.43.2551,022
1227.232.44.0/2227.232.44.1 to 27.232.47.25427.232.47.2551,022
1327.232.48.0/2227.232.48.1 to 27.232.51.25427.232.51.2551,022
1427.232.52.0/2227.232.52.1 to 27.232.55.25427.232.55.2551,022
1527.232.56.0/2227.232.56.1 to 27.232.59.25427.232.59.2551,022
1627.232.60.0/2227.232.60.1 to 27.232.63.25427.232.63.2551,022
1727.232.64.0/2227.232.64.1 to 27.232.67.25427.232.67.2551,022
1827.232.68.0/2227.232.68.1 to 27.232.71.25427.232.71.2551,022
1927.232.72.0/2227.232.72.1 to 27.232.75.25427.232.75.2551,022
2027.232.76.0/2227.232.76.1 to 27.232.79.25427.232.79.2551,022
2127.232.80.0/2227.232.80.1 to 27.232.83.25427.232.83.2551,022
2227.232.84.0/2227.232.84.1 to 27.232.87.25427.232.87.2551,022
2327.232.88.0/2227.232.88.1 to 27.232.91.25427.232.91.2551,022
2427.232.92.0/2227.232.92.1 to 27.232.95.25427.232.95.2551,022
2527.232.96.0/2227.232.96.1 to 27.232.99.25427.232.99.2551,022
2627.232.100.0/2227.232.100.1 to 27.232.103.25427.232.103.2551,022
2727.232.104.0/2227.232.104.1 to 27.232.107.25427.232.107.2551,022
2827.232.108.0/2227.232.108.1 to 27.232.111.25427.232.111.2551,022
2927.232.112.0/2227.232.112.1 to 27.232.115.25427.232.115.2551,022
3027.232.116.0/2227.232.116.1 to 27.232.119.25427.232.119.2551,022
3127.232.120.0/2227.232.120.1 to 27.232.123.25427.232.123.2551,022
3227.232.124.0/2227.232.124.1 to 27.232.127.25427.232.127.2551,022
3327.232.128.0/2227.232.128.1 to 27.232.131.25427.232.131.2551,022
3427.232.132.0/2227.232.132.1 to 27.232.135.25427.232.135.2551,022
3527.232.136.0/2227.232.136.1 to 27.232.139.25427.232.139.2551,022
3627.232.140.0/2227.232.140.1 to 27.232.143.25427.232.143.2551,022
3727.232.144.0/2227.232.144.1 to 27.232.147.25427.232.147.2551,022
3827.232.148.0/2227.232.148.1 to 27.232.151.25427.232.151.2551,022
3927.232.152.0/2227.232.152.1 to 27.232.155.25427.232.155.2551,022
4027.232.156.0/2227.232.156.1 to 27.232.159.25427.232.159.2551,022
4127.232.160.0/2227.232.160.1 to 27.232.163.25427.232.163.2551,022
4227.232.164.0/2227.232.164.1 to 27.232.167.25427.232.167.2551,022
4327.232.168.0/2227.232.168.1 to 27.232.171.25427.232.171.2551,022
4427.232.172.0/2227.232.172.1 to 27.232.175.25427.232.175.2551,022
4527.232.176.0/2227.232.176.1 to 27.232.179.25427.232.179.2551,022
4627.232.180.0/2227.232.180.1 to 27.232.183.25427.232.183.2551,022
4727.232.184.0/2227.232.184.1 to 27.232.187.25427.232.187.2551,022
4827.232.188.0/2227.232.188.1 to 27.232.191.25427.232.191.2551,022
4927.232.192.0/2227.232.192.1 to 27.232.195.25427.232.195.2551,022
5027.232.196.0/2227.232.196.1 to 27.232.199.25427.232.199.2551,022
5127.232.200.0/2227.232.200.1 to 27.232.203.25427.232.203.2551,022
5227.232.204.0/2227.232.204.1 to 27.232.207.25427.232.207.2551,022
5327.232.208.0/2227.232.208.1 to 27.232.211.25427.232.211.2551,022
5427.232.212.0/2227.232.212.1 to 27.232.215.25427.232.215.2551,022
5527.232.216.0/2227.232.216.1 to 27.232.219.25427.232.219.2551,022
5627.232.220.0/2227.232.220.1 to 27.232.223.25427.232.223.2551,022
5727.232.224.0/2227.232.224.1 to 27.232.227.25427.232.227.2551,022
5827.232.228.0/2227.232.228.1 to 27.232.231.25427.232.231.2551,022
5927.232.232.0/2227.232.232.1 to 27.232.235.25427.232.235.2551,022
6027.232.236.0/2227.232.236.1 to 27.232.239.25427.232.239.2551,022
6127.232.240.0/2227.232.240.1 to 27.232.243.25427.232.243.2551,022
6227.232.244.0/2227.232.244.1 to 27.232.247.25427.232.247.2551,022
6327.232.248.0/2227.232.248.1 to 27.232.251.25427.232.251.2551,022
6427.232.252.0/2227.232.252.1 to 27.232.255.25427.232.255.2551,022
6527.233.0.0/2227.233.0.1 to 27.233.3.25427.233.3.2551,022
6627.233.4.0/2227.233.4.1 to 27.233.7.25427.233.7.2551,022
6727.233.8.0/2227.233.8.1 to 27.233.11.25427.233.11.2551,022
6827.233.12.0/2227.233.12.1 to 27.233.15.25427.233.15.2551,022
6927.233.16.0/2227.233.16.1 to 27.233.19.25427.233.19.2551,022
7027.233.20.0/2227.233.20.1 to 27.233.23.25427.233.23.2551,022
7127.233.24.0/2227.233.24.1 to 27.233.27.25427.233.27.2551,022
7227.233.28.0/2227.233.28.1 to 27.233.31.25427.233.31.2551,022
7327.233.32.0/2227.233.32.1 to 27.233.35.25427.233.35.2551,022
7427.233.36.0/2227.233.36.1 to 27.233.39.25427.233.39.2551,022
7527.233.40.0/2227.233.40.1 to 27.233.43.25427.233.43.2551,022
7627.233.44.0/2227.233.44.1 to 27.233.47.25427.233.47.2551,022
7727.233.48.0/2227.233.48.1 to 27.233.51.25427.233.51.2551,022
7827.233.52.0/2227.233.52.1 to 27.233.55.25427.233.55.2551,022
7927.233.56.0/2227.233.56.1 to 27.233.59.25427.233.59.2551,022
8027.233.60.0/2227.233.60.1 to 27.233.63.25427.233.63.2551,022
8127.233.64.0/2227.233.64.1 to 27.233.67.25427.233.67.2551,022
8227.233.68.0/2227.233.68.1 to 27.233.71.25427.233.71.2551,022
8327.233.72.0/2227.233.72.1 to 27.233.75.25427.233.75.2551,022
8427.233.76.0/2227.233.76.1 to 27.233.79.25427.233.79.2551,022
8527.233.80.0/2227.233.80.1 to 27.233.83.25427.233.83.2551,022
8627.233.84.0/2227.233.84.1 to 27.233.87.25427.233.87.2551,022
8727.233.88.0/2227.233.88.1 to 27.233.91.25427.233.91.2551,022
8827.233.92.0/2227.233.92.1 to 27.233.95.25427.233.95.2551,022
8927.233.96.0/2227.233.96.1 to 27.233.99.25427.233.99.2551,022
9027.233.100.0/2227.233.100.1 to 27.233.103.25427.233.103.2551,022
9127.233.104.0/2227.233.104.1 to 27.233.107.25427.233.107.2551,022
9227.233.108.0/2227.233.108.1 to 27.233.111.25427.233.111.2551,022
9327.233.112.0/2227.233.112.1 to 27.233.115.25427.233.115.2551,022
9427.233.116.0/2227.233.116.1 to 27.233.119.25427.233.119.2551,022
9527.233.120.0/2227.233.120.1 to 27.233.123.25427.233.123.2551,022
9627.233.124.0/2227.233.124.1 to 27.233.127.25427.233.127.2551,022
9727.233.128.0/2227.233.128.1 to 27.233.131.25427.233.131.2551,022
9827.233.132.0/2227.233.132.1 to 27.233.135.25427.233.135.2551,022
9927.233.136.0/2227.233.136.1 to 27.233.139.25427.233.139.2551,022
10027.233.140.0/2227.233.140.1 to 27.233.143.25427.233.143.2551,022
10127.233.144.0/2227.233.144.1 to 27.233.147.25427.233.147.2551,022
10227.233.148.0/2227.233.148.1 to 27.233.151.25427.233.151.2551,022
10327.233.152.0/2227.233.152.1 to 27.233.155.25427.233.155.2551,022
10427.233.156.0/2227.233.156.1 to 27.233.159.25427.233.159.2551,022
10527.233.160.0/2227.233.160.1 to 27.233.163.25427.233.163.2551,022
10627.233.164.0/2227.233.164.1 to 27.233.167.25427.233.167.2551,022
10727.233.168.0/2227.233.168.1 to 27.233.171.25427.233.171.2551,022
10827.233.172.0/2227.233.172.1 to 27.233.175.25427.233.175.2551,022
10927.233.176.0/2227.233.176.1 to 27.233.179.25427.233.179.2551,022
11027.233.180.0/2227.233.180.1 to 27.233.183.25427.233.183.2551,022
11127.233.184.0/2227.233.184.1 to 27.233.187.25427.233.187.2551,022
11227.233.188.0/2227.233.188.1 to 27.233.191.25427.233.191.2551,022
11327.233.192.0/2227.233.192.1 to 27.233.195.25427.233.195.2551,022
11427.233.196.0/2227.233.196.1 to 27.233.199.25427.233.199.2551,022
11527.233.200.0/2227.233.200.1 to 27.233.203.25427.233.203.2551,022
11627.233.204.0/2227.233.204.1 to 27.233.207.25427.233.207.2551,022
11727.233.208.0/2227.233.208.1 to 27.233.211.25427.233.211.2551,022
11827.233.212.0/2227.233.212.1 to 27.233.215.25427.233.215.2551,022
11927.233.216.0/2227.233.216.1 to 27.233.219.25427.233.219.2551,022
12027.233.220.0/2227.233.220.1 to 27.233.223.25427.233.223.2551,022
12127.233.224.0/2227.233.224.1 to 27.233.227.25427.233.227.2551,022
12227.233.228.0/2227.233.228.1 to 27.233.231.25427.233.231.2551,022
12327.233.232.0/2227.233.232.1 to 27.233.235.25427.233.235.2551,022
12427.233.236.0/2227.233.236.1 to 27.233.239.25427.233.239.2551,022
12527.233.240.0/2227.233.240.1 to 27.233.243.25427.233.243.2551,022
12627.233.244.0/2227.233.244.1 to 27.233.247.25427.233.247.2551,022
12727.233.248.0/2227.233.248.1 to 27.233.251.25427.233.251.2551,022
12827.233.252.0/2227.233.252.1 to 27.233.255.25427.233.255.2551,022

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.