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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.

Network97.80.0.0/15
Usable hosts131,070
Subnet mask255.254.0.0
Addresses131,072
Network address
97.80.0.0
Broadcast address
97.81.255.255
First usable
97.80.0.1
Last usable
97.81.255.254
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 61500000 · Integer 1632632832 to 1632763903
Reverse DNS zones
80.97.in-addr.arpa
81.97.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
Address01100001.01010000.00000000.0000000097.80.0.0
Subnet mask11111111.11111110.00000000.00000000255.254.0.0
Network01100001.01010000.00000000.0000000097.80.0.0
Broadcast01100001.01010001.11111111.1111111197.81.255.255
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)

97.80.0.0/15 makes 128 subnets of /22.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
197.80.0.0/2297.80.0.1 to 97.80.3.25497.80.3.2551,022
297.80.4.0/2297.80.4.1 to 97.80.7.25497.80.7.2551,022
397.80.8.0/2297.80.8.1 to 97.80.11.25497.80.11.2551,022
497.80.12.0/2297.80.12.1 to 97.80.15.25497.80.15.2551,022
597.80.16.0/2297.80.16.1 to 97.80.19.25497.80.19.2551,022
697.80.20.0/2297.80.20.1 to 97.80.23.25497.80.23.2551,022
797.80.24.0/2297.80.24.1 to 97.80.27.25497.80.27.2551,022
897.80.28.0/2297.80.28.1 to 97.80.31.25497.80.31.2551,022
997.80.32.0/2297.80.32.1 to 97.80.35.25497.80.35.2551,022
1097.80.36.0/2297.80.36.1 to 97.80.39.25497.80.39.2551,022
1197.80.40.0/2297.80.40.1 to 97.80.43.25497.80.43.2551,022
1297.80.44.0/2297.80.44.1 to 97.80.47.25497.80.47.2551,022
1397.80.48.0/2297.80.48.1 to 97.80.51.25497.80.51.2551,022
1497.80.52.0/2297.80.52.1 to 97.80.55.25497.80.55.2551,022
1597.80.56.0/2297.80.56.1 to 97.80.59.25497.80.59.2551,022
1697.80.60.0/2297.80.60.1 to 97.80.63.25497.80.63.2551,022
1797.80.64.0/2297.80.64.1 to 97.80.67.25497.80.67.2551,022
1897.80.68.0/2297.80.68.1 to 97.80.71.25497.80.71.2551,022
1997.80.72.0/2297.80.72.1 to 97.80.75.25497.80.75.2551,022
2097.80.76.0/2297.80.76.1 to 97.80.79.25497.80.79.2551,022
2197.80.80.0/2297.80.80.1 to 97.80.83.25497.80.83.2551,022
2297.80.84.0/2297.80.84.1 to 97.80.87.25497.80.87.2551,022
2397.80.88.0/2297.80.88.1 to 97.80.91.25497.80.91.2551,022
2497.80.92.0/2297.80.92.1 to 97.80.95.25497.80.95.2551,022
2597.80.96.0/2297.80.96.1 to 97.80.99.25497.80.99.2551,022
2697.80.100.0/2297.80.100.1 to 97.80.103.25497.80.103.2551,022
2797.80.104.0/2297.80.104.1 to 97.80.107.25497.80.107.2551,022
2897.80.108.0/2297.80.108.1 to 97.80.111.25497.80.111.2551,022
2997.80.112.0/2297.80.112.1 to 97.80.115.25497.80.115.2551,022
3097.80.116.0/2297.80.116.1 to 97.80.119.25497.80.119.2551,022
3197.80.120.0/2297.80.120.1 to 97.80.123.25497.80.123.2551,022
3297.80.124.0/2297.80.124.1 to 97.80.127.25497.80.127.2551,022
3397.80.128.0/2297.80.128.1 to 97.80.131.25497.80.131.2551,022
3497.80.132.0/2297.80.132.1 to 97.80.135.25497.80.135.2551,022
3597.80.136.0/2297.80.136.1 to 97.80.139.25497.80.139.2551,022
3697.80.140.0/2297.80.140.1 to 97.80.143.25497.80.143.2551,022
3797.80.144.0/2297.80.144.1 to 97.80.147.25497.80.147.2551,022
3897.80.148.0/2297.80.148.1 to 97.80.151.25497.80.151.2551,022
3997.80.152.0/2297.80.152.1 to 97.80.155.25497.80.155.2551,022
4097.80.156.0/2297.80.156.1 to 97.80.159.25497.80.159.2551,022
4197.80.160.0/2297.80.160.1 to 97.80.163.25497.80.163.2551,022
4297.80.164.0/2297.80.164.1 to 97.80.167.25497.80.167.2551,022
4397.80.168.0/2297.80.168.1 to 97.80.171.25497.80.171.2551,022
4497.80.172.0/2297.80.172.1 to 97.80.175.25497.80.175.2551,022
4597.80.176.0/2297.80.176.1 to 97.80.179.25497.80.179.2551,022
4697.80.180.0/2297.80.180.1 to 97.80.183.25497.80.183.2551,022
4797.80.184.0/2297.80.184.1 to 97.80.187.25497.80.187.2551,022
4897.80.188.0/2297.80.188.1 to 97.80.191.25497.80.191.2551,022
4997.80.192.0/2297.80.192.1 to 97.80.195.25497.80.195.2551,022
5097.80.196.0/2297.80.196.1 to 97.80.199.25497.80.199.2551,022
5197.80.200.0/2297.80.200.1 to 97.80.203.25497.80.203.2551,022
5297.80.204.0/2297.80.204.1 to 97.80.207.25497.80.207.2551,022
5397.80.208.0/2297.80.208.1 to 97.80.211.25497.80.211.2551,022
5497.80.212.0/2297.80.212.1 to 97.80.215.25497.80.215.2551,022
5597.80.216.0/2297.80.216.1 to 97.80.219.25497.80.219.2551,022
5697.80.220.0/2297.80.220.1 to 97.80.223.25497.80.223.2551,022
5797.80.224.0/2297.80.224.1 to 97.80.227.25497.80.227.2551,022
5897.80.228.0/2297.80.228.1 to 97.80.231.25497.80.231.2551,022
5997.80.232.0/2297.80.232.1 to 97.80.235.25497.80.235.2551,022
6097.80.236.0/2297.80.236.1 to 97.80.239.25497.80.239.2551,022
6197.80.240.0/2297.80.240.1 to 97.80.243.25497.80.243.2551,022
6297.80.244.0/2297.80.244.1 to 97.80.247.25497.80.247.2551,022
6397.80.248.0/2297.80.248.1 to 97.80.251.25497.80.251.2551,022
6497.80.252.0/2297.80.252.1 to 97.80.255.25497.80.255.2551,022
6597.81.0.0/2297.81.0.1 to 97.81.3.25497.81.3.2551,022
6697.81.4.0/2297.81.4.1 to 97.81.7.25497.81.7.2551,022
6797.81.8.0/2297.81.8.1 to 97.81.11.25497.81.11.2551,022
6897.81.12.0/2297.81.12.1 to 97.81.15.25497.81.15.2551,022
6997.81.16.0/2297.81.16.1 to 97.81.19.25497.81.19.2551,022
7097.81.20.0/2297.81.20.1 to 97.81.23.25497.81.23.2551,022
7197.81.24.0/2297.81.24.1 to 97.81.27.25497.81.27.2551,022
7297.81.28.0/2297.81.28.1 to 97.81.31.25497.81.31.2551,022
7397.81.32.0/2297.81.32.1 to 97.81.35.25497.81.35.2551,022
7497.81.36.0/2297.81.36.1 to 97.81.39.25497.81.39.2551,022
7597.81.40.0/2297.81.40.1 to 97.81.43.25497.81.43.2551,022
7697.81.44.0/2297.81.44.1 to 97.81.47.25497.81.47.2551,022
7797.81.48.0/2297.81.48.1 to 97.81.51.25497.81.51.2551,022
7897.81.52.0/2297.81.52.1 to 97.81.55.25497.81.55.2551,022
7997.81.56.0/2297.81.56.1 to 97.81.59.25497.81.59.2551,022
8097.81.60.0/2297.81.60.1 to 97.81.63.25497.81.63.2551,022
8197.81.64.0/2297.81.64.1 to 97.81.67.25497.81.67.2551,022
8297.81.68.0/2297.81.68.1 to 97.81.71.25497.81.71.2551,022
8397.81.72.0/2297.81.72.1 to 97.81.75.25497.81.75.2551,022
8497.81.76.0/2297.81.76.1 to 97.81.79.25497.81.79.2551,022
8597.81.80.0/2297.81.80.1 to 97.81.83.25497.81.83.2551,022
8697.81.84.0/2297.81.84.1 to 97.81.87.25497.81.87.2551,022
8797.81.88.0/2297.81.88.1 to 97.81.91.25497.81.91.2551,022
8897.81.92.0/2297.81.92.1 to 97.81.95.25497.81.95.2551,022
8997.81.96.0/2297.81.96.1 to 97.81.99.25497.81.99.2551,022
9097.81.100.0/2297.81.100.1 to 97.81.103.25497.81.103.2551,022
9197.81.104.0/2297.81.104.1 to 97.81.107.25497.81.107.2551,022
9297.81.108.0/2297.81.108.1 to 97.81.111.25497.81.111.2551,022
9397.81.112.0/2297.81.112.1 to 97.81.115.25497.81.115.2551,022
9497.81.116.0/2297.81.116.1 to 97.81.119.25497.81.119.2551,022
9597.81.120.0/2297.81.120.1 to 97.81.123.25497.81.123.2551,022
9697.81.124.0/2297.81.124.1 to 97.81.127.25497.81.127.2551,022
9797.81.128.0/2297.81.128.1 to 97.81.131.25497.81.131.2551,022
9897.81.132.0/2297.81.132.1 to 97.81.135.25497.81.135.2551,022
9997.81.136.0/2297.81.136.1 to 97.81.139.25497.81.139.2551,022
10097.81.140.0/2297.81.140.1 to 97.81.143.25497.81.143.2551,022
10197.81.144.0/2297.81.144.1 to 97.81.147.25497.81.147.2551,022
10297.81.148.0/2297.81.148.1 to 97.81.151.25497.81.151.2551,022
10397.81.152.0/2297.81.152.1 to 97.81.155.25497.81.155.2551,022
10497.81.156.0/2297.81.156.1 to 97.81.159.25497.81.159.2551,022
10597.81.160.0/2297.81.160.1 to 97.81.163.25497.81.163.2551,022
10697.81.164.0/2297.81.164.1 to 97.81.167.25497.81.167.2551,022
10797.81.168.0/2297.81.168.1 to 97.81.171.25497.81.171.2551,022
10897.81.172.0/2297.81.172.1 to 97.81.175.25497.81.175.2551,022
10997.81.176.0/2297.81.176.1 to 97.81.179.25497.81.179.2551,022
11097.81.180.0/2297.81.180.1 to 97.81.183.25497.81.183.2551,022
11197.81.184.0/2297.81.184.1 to 97.81.187.25497.81.187.2551,022
11297.81.188.0/2297.81.188.1 to 97.81.191.25497.81.191.2551,022
11397.81.192.0/2297.81.192.1 to 97.81.195.25497.81.195.2551,022
11497.81.196.0/2297.81.196.1 to 97.81.199.25497.81.199.2551,022
11597.81.200.0/2297.81.200.1 to 97.81.203.25497.81.203.2551,022
11697.81.204.0/2297.81.204.1 to 97.81.207.25497.81.207.2551,022
11797.81.208.0/2297.81.208.1 to 97.81.211.25497.81.211.2551,022
11897.81.212.0/2297.81.212.1 to 97.81.215.25497.81.215.2551,022
11997.81.216.0/2297.81.216.1 to 97.81.219.25497.81.219.2551,022
12097.81.220.0/2297.81.220.1 to 97.81.223.25497.81.223.2551,022
12197.81.224.0/2297.81.224.1 to 97.81.227.25497.81.227.2551,022
12297.81.228.0/2297.81.228.1 to 97.81.231.25497.81.231.2551,022
12397.81.232.0/2297.81.232.1 to 97.81.235.25497.81.235.2551,022
12497.81.236.0/2297.81.236.1 to 97.81.239.25497.81.239.2551,022
12597.81.240.0/2297.81.240.1 to 97.81.243.25497.81.243.2551,022
12697.81.244.0/2297.81.244.1 to 97.81.247.25497.81.247.2551,022
12797.81.248.0/2297.81.248.1 to 97.81.251.25497.81.251.2551,022
12897.81.252.0/2297.81.252.1 to 97.81.255.25497.81.255.2551,022

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.