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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.

Network97.72.0.0/13
Usable hosts524,286
Subnet mask255.248.0.0
Addresses524,288
Network address
97.72.0.0
Broadcast address
97.79.255.255
First usable
97.72.0.1
Last usable
97.79.255.254
Usable hosts
524,286 (524,288 less the network and broadcast addresses)
Subnet mask
255.248.0.0
Wildcard mask
0.7.255.255 (Cisco ACLs, OSPF)
Prefix length
/13
Type
Public public
Old class
A (default /8)
As numbers
Hex 61480000 · Integer 1632108544 to 1632632831
Reverse DNS zones
72.97.in-addr.arpa
73.97.in-addr.arpa
74.97.in-addr.arpa
75.97.in-addr.arpa
76.97.in-addr.arpa
77.97.in-addr.arpa
78.97.in-addr.arpa
79.97.in-addr.arpa
/13 is not on a 8-bit boundary, so it takes 8 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01100001.01001000.00000000.0000000097.72.0.0
Subnet mask11111111.11111000.00000000.00000000255.248.0.0
Network01100001.01001000.00000000.0000000097.72.0.0
Broadcast01100001.01001111.11111111.1111111197.79.255.255
Split into smaller subnets/20
/14 (2)/15 (4)/16 (8)/17 (16)/18 (32)/19 (64)/20 (128)/21 (256)/22 (512)/23 (1,024)/24 (2,048)/25 (4,096)

97.72.0.0/13 makes 128 subnets of /20.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
197.72.0.0/2097.72.0.1 to 97.72.15.25497.72.15.2554,094
297.72.16.0/2097.72.16.1 to 97.72.31.25497.72.31.2554,094
397.72.32.0/2097.72.32.1 to 97.72.47.25497.72.47.2554,094
497.72.48.0/2097.72.48.1 to 97.72.63.25497.72.63.2554,094
597.72.64.0/2097.72.64.1 to 97.72.79.25497.72.79.2554,094
697.72.80.0/2097.72.80.1 to 97.72.95.25497.72.95.2554,094
797.72.96.0/2097.72.96.1 to 97.72.111.25497.72.111.2554,094
897.72.112.0/2097.72.112.1 to 97.72.127.25497.72.127.2554,094
997.72.128.0/2097.72.128.1 to 97.72.143.25497.72.143.2554,094
1097.72.144.0/2097.72.144.1 to 97.72.159.25497.72.159.2554,094
1197.72.160.0/2097.72.160.1 to 97.72.175.25497.72.175.2554,094
1297.72.176.0/2097.72.176.1 to 97.72.191.25497.72.191.2554,094
1397.72.192.0/2097.72.192.1 to 97.72.207.25497.72.207.2554,094
1497.72.208.0/2097.72.208.1 to 97.72.223.25497.72.223.2554,094
1597.72.224.0/2097.72.224.1 to 97.72.239.25497.72.239.2554,094
1697.72.240.0/2097.72.240.1 to 97.72.255.25497.72.255.2554,094
1797.73.0.0/2097.73.0.1 to 97.73.15.25497.73.15.2554,094
1897.73.16.0/2097.73.16.1 to 97.73.31.25497.73.31.2554,094
1997.73.32.0/2097.73.32.1 to 97.73.47.25497.73.47.2554,094
2097.73.48.0/2097.73.48.1 to 97.73.63.25497.73.63.2554,094
2197.73.64.0/2097.73.64.1 to 97.73.79.25497.73.79.2554,094
2297.73.80.0/2097.73.80.1 to 97.73.95.25497.73.95.2554,094
2397.73.96.0/2097.73.96.1 to 97.73.111.25497.73.111.2554,094
2497.73.112.0/2097.73.112.1 to 97.73.127.25497.73.127.2554,094
2597.73.128.0/2097.73.128.1 to 97.73.143.25497.73.143.2554,094
2697.73.144.0/2097.73.144.1 to 97.73.159.25497.73.159.2554,094
2797.73.160.0/2097.73.160.1 to 97.73.175.25497.73.175.2554,094
2897.73.176.0/2097.73.176.1 to 97.73.191.25497.73.191.2554,094
2997.73.192.0/2097.73.192.1 to 97.73.207.25497.73.207.2554,094
3097.73.208.0/2097.73.208.1 to 97.73.223.25497.73.223.2554,094
3197.73.224.0/2097.73.224.1 to 97.73.239.25497.73.239.2554,094
3297.73.240.0/2097.73.240.1 to 97.73.255.25497.73.255.2554,094
3397.74.0.0/2097.74.0.1 to 97.74.15.25497.74.15.2554,094
3497.74.16.0/2097.74.16.1 to 97.74.31.25497.74.31.2554,094
3597.74.32.0/2097.74.32.1 to 97.74.47.25497.74.47.2554,094
3697.74.48.0/2097.74.48.1 to 97.74.63.25497.74.63.2554,094
3797.74.64.0/2097.74.64.1 to 97.74.79.25497.74.79.2554,094
3897.74.80.0/2097.74.80.1 to 97.74.95.25497.74.95.2554,094
3997.74.96.0/2097.74.96.1 to 97.74.111.25497.74.111.2554,094
4097.74.112.0/2097.74.112.1 to 97.74.127.25497.74.127.2554,094
4197.74.128.0/2097.74.128.1 to 97.74.143.25497.74.143.2554,094
4297.74.144.0/2097.74.144.1 to 97.74.159.25497.74.159.2554,094
4397.74.160.0/2097.74.160.1 to 97.74.175.25497.74.175.2554,094
4497.74.176.0/2097.74.176.1 to 97.74.191.25497.74.191.2554,094
4597.74.192.0/2097.74.192.1 to 97.74.207.25497.74.207.2554,094
4697.74.208.0/2097.74.208.1 to 97.74.223.25497.74.223.2554,094
4797.74.224.0/2097.74.224.1 to 97.74.239.25497.74.239.2554,094
4897.74.240.0/2097.74.240.1 to 97.74.255.25497.74.255.2554,094
4997.75.0.0/2097.75.0.1 to 97.75.15.25497.75.15.2554,094
5097.75.16.0/2097.75.16.1 to 97.75.31.25497.75.31.2554,094
5197.75.32.0/2097.75.32.1 to 97.75.47.25497.75.47.2554,094
5297.75.48.0/2097.75.48.1 to 97.75.63.25497.75.63.2554,094
5397.75.64.0/2097.75.64.1 to 97.75.79.25497.75.79.2554,094
5497.75.80.0/2097.75.80.1 to 97.75.95.25497.75.95.2554,094
5597.75.96.0/2097.75.96.1 to 97.75.111.25497.75.111.2554,094
5697.75.112.0/2097.75.112.1 to 97.75.127.25497.75.127.2554,094
5797.75.128.0/2097.75.128.1 to 97.75.143.25497.75.143.2554,094
5897.75.144.0/2097.75.144.1 to 97.75.159.25497.75.159.2554,094
5997.75.160.0/2097.75.160.1 to 97.75.175.25497.75.175.2554,094
6097.75.176.0/2097.75.176.1 to 97.75.191.25497.75.191.2554,094
6197.75.192.0/2097.75.192.1 to 97.75.207.25497.75.207.2554,094
6297.75.208.0/2097.75.208.1 to 97.75.223.25497.75.223.2554,094
6397.75.224.0/2097.75.224.1 to 97.75.239.25497.75.239.2554,094
6497.75.240.0/2097.75.240.1 to 97.75.255.25497.75.255.2554,094
6597.76.0.0/2097.76.0.1 to 97.76.15.25497.76.15.2554,094
6697.76.16.0/2097.76.16.1 to 97.76.31.25497.76.31.2554,094
6797.76.32.0/2097.76.32.1 to 97.76.47.25497.76.47.2554,094
6897.76.48.0/2097.76.48.1 to 97.76.63.25497.76.63.2554,094
6997.76.64.0/2097.76.64.1 to 97.76.79.25497.76.79.2554,094
7097.76.80.0/2097.76.80.1 to 97.76.95.25497.76.95.2554,094
7197.76.96.0/2097.76.96.1 to 97.76.111.25497.76.111.2554,094
7297.76.112.0/2097.76.112.1 to 97.76.127.25497.76.127.2554,094
7397.76.128.0/2097.76.128.1 to 97.76.143.25497.76.143.2554,094
7497.76.144.0/2097.76.144.1 to 97.76.159.25497.76.159.2554,094
7597.76.160.0/2097.76.160.1 to 97.76.175.25497.76.175.2554,094
7697.76.176.0/2097.76.176.1 to 97.76.191.25497.76.191.2554,094
7797.76.192.0/2097.76.192.1 to 97.76.207.25497.76.207.2554,094
7897.76.208.0/2097.76.208.1 to 97.76.223.25497.76.223.2554,094
7997.76.224.0/2097.76.224.1 to 97.76.239.25497.76.239.2554,094
8097.76.240.0/2097.76.240.1 to 97.76.255.25497.76.255.2554,094
8197.77.0.0/2097.77.0.1 to 97.77.15.25497.77.15.2554,094
8297.77.16.0/2097.77.16.1 to 97.77.31.25497.77.31.2554,094
8397.77.32.0/2097.77.32.1 to 97.77.47.25497.77.47.2554,094
8497.77.48.0/2097.77.48.1 to 97.77.63.25497.77.63.2554,094
8597.77.64.0/2097.77.64.1 to 97.77.79.25497.77.79.2554,094
8697.77.80.0/2097.77.80.1 to 97.77.95.25497.77.95.2554,094
8797.77.96.0/2097.77.96.1 to 97.77.111.25497.77.111.2554,094
8897.77.112.0/2097.77.112.1 to 97.77.127.25497.77.127.2554,094
8997.77.128.0/2097.77.128.1 to 97.77.143.25497.77.143.2554,094
9097.77.144.0/2097.77.144.1 to 97.77.159.25497.77.159.2554,094
9197.77.160.0/2097.77.160.1 to 97.77.175.25497.77.175.2554,094
9297.77.176.0/2097.77.176.1 to 97.77.191.25497.77.191.2554,094
9397.77.192.0/2097.77.192.1 to 97.77.207.25497.77.207.2554,094
9497.77.208.0/2097.77.208.1 to 97.77.223.25497.77.223.2554,094
9597.77.224.0/2097.77.224.1 to 97.77.239.25497.77.239.2554,094
9697.77.240.0/2097.77.240.1 to 97.77.255.25497.77.255.2554,094
9797.78.0.0/2097.78.0.1 to 97.78.15.25497.78.15.2554,094
9897.78.16.0/2097.78.16.1 to 97.78.31.25497.78.31.2554,094
9997.78.32.0/2097.78.32.1 to 97.78.47.25497.78.47.2554,094
10097.78.48.0/2097.78.48.1 to 97.78.63.25497.78.63.2554,094
10197.78.64.0/2097.78.64.1 to 97.78.79.25497.78.79.2554,094
10297.78.80.0/2097.78.80.1 to 97.78.95.25497.78.95.2554,094
10397.78.96.0/2097.78.96.1 to 97.78.111.25497.78.111.2554,094
10497.78.112.0/2097.78.112.1 to 97.78.127.25497.78.127.2554,094
10597.78.128.0/2097.78.128.1 to 97.78.143.25497.78.143.2554,094
10697.78.144.0/2097.78.144.1 to 97.78.159.25497.78.159.2554,094
10797.78.160.0/2097.78.160.1 to 97.78.175.25497.78.175.2554,094
10897.78.176.0/2097.78.176.1 to 97.78.191.25497.78.191.2554,094
10997.78.192.0/2097.78.192.1 to 97.78.207.25497.78.207.2554,094
11097.78.208.0/2097.78.208.1 to 97.78.223.25497.78.223.2554,094
11197.78.224.0/2097.78.224.1 to 97.78.239.25497.78.239.2554,094
11297.78.240.0/2097.78.240.1 to 97.78.255.25497.78.255.2554,094
11397.79.0.0/2097.79.0.1 to 97.79.15.25497.79.15.2554,094
11497.79.16.0/2097.79.16.1 to 97.79.31.25497.79.31.2554,094
11597.79.32.0/2097.79.32.1 to 97.79.47.25497.79.47.2554,094
11697.79.48.0/2097.79.48.1 to 97.79.63.25497.79.63.2554,094
11797.79.64.0/2097.79.64.1 to 97.79.79.25497.79.79.2554,094
11897.79.80.0/2097.79.80.1 to 97.79.95.25497.79.95.2554,094
11997.79.96.0/2097.79.96.1 to 97.79.111.25497.79.111.2554,094
12097.79.112.0/2097.79.112.1 to 97.79.127.25497.79.127.2554,094
12197.79.128.0/2097.79.128.1 to 97.79.143.25497.79.143.2554,094
12297.79.144.0/2097.79.144.1 to 97.79.159.25497.79.159.2554,094
12397.79.160.0/2097.79.160.1 to 97.79.175.25497.79.175.2554,094
12497.79.176.0/2097.79.176.1 to 97.79.191.25497.79.191.2554,094
12597.79.192.0/2097.79.192.1 to 97.79.207.25497.79.207.2554,094
12697.79.208.0/2097.79.208.1 to 97.79.223.25497.79.223.2554,094
12797.79.224.0/2097.79.224.1 to 97.79.239.25497.79.239.2554,094
12897.79.240.0/2097.79.240.1 to 97.79.255.25497.79.255.2554,094

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.