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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.

Network75.72.0.0/13
Usable hosts524,286
Subnet mask255.248.0.0
Addresses524,288
Network address
75.72.0.0
Broadcast address
75.79.255.255
First usable
75.72.0.1
Last usable
75.79.255.254
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 4B480000 · Integer 1263009792 to 1263534079
Reverse DNS zones
72.75.in-addr.arpa
73.75.in-addr.arpa
74.75.in-addr.arpa
75.75.in-addr.arpa
76.75.in-addr.arpa
77.75.in-addr.arpa
78.75.in-addr.arpa
79.75.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
Address01001011.01001000.00000000.0000000075.72.0.0
Subnet mask11111111.11111000.00000000.00000000255.248.0.0
Network01001011.01001000.00000000.0000000075.72.0.0
Broadcast01001011.01001111.11111111.1111111175.79.255.255
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)

75.72.0.0/13 makes 128 subnets of /20.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
175.72.0.0/2075.72.0.1 to 75.72.15.25475.72.15.2554,094
275.72.16.0/2075.72.16.1 to 75.72.31.25475.72.31.2554,094
375.72.32.0/2075.72.32.1 to 75.72.47.25475.72.47.2554,094
475.72.48.0/2075.72.48.1 to 75.72.63.25475.72.63.2554,094
575.72.64.0/2075.72.64.1 to 75.72.79.25475.72.79.2554,094
675.72.80.0/2075.72.80.1 to 75.72.95.25475.72.95.2554,094
775.72.96.0/2075.72.96.1 to 75.72.111.25475.72.111.2554,094
875.72.112.0/2075.72.112.1 to 75.72.127.25475.72.127.2554,094
975.72.128.0/2075.72.128.1 to 75.72.143.25475.72.143.2554,094
1075.72.144.0/2075.72.144.1 to 75.72.159.25475.72.159.2554,094
1175.72.160.0/2075.72.160.1 to 75.72.175.25475.72.175.2554,094
1275.72.176.0/2075.72.176.1 to 75.72.191.25475.72.191.2554,094
1375.72.192.0/2075.72.192.1 to 75.72.207.25475.72.207.2554,094
1475.72.208.0/2075.72.208.1 to 75.72.223.25475.72.223.2554,094
1575.72.224.0/2075.72.224.1 to 75.72.239.25475.72.239.2554,094
1675.72.240.0/2075.72.240.1 to 75.72.255.25475.72.255.2554,094
1775.73.0.0/2075.73.0.1 to 75.73.15.25475.73.15.2554,094
1875.73.16.0/2075.73.16.1 to 75.73.31.25475.73.31.2554,094
1975.73.32.0/2075.73.32.1 to 75.73.47.25475.73.47.2554,094
2075.73.48.0/2075.73.48.1 to 75.73.63.25475.73.63.2554,094
2175.73.64.0/2075.73.64.1 to 75.73.79.25475.73.79.2554,094
2275.73.80.0/2075.73.80.1 to 75.73.95.25475.73.95.2554,094
2375.73.96.0/2075.73.96.1 to 75.73.111.25475.73.111.2554,094
2475.73.112.0/2075.73.112.1 to 75.73.127.25475.73.127.2554,094
2575.73.128.0/2075.73.128.1 to 75.73.143.25475.73.143.2554,094
2675.73.144.0/2075.73.144.1 to 75.73.159.25475.73.159.2554,094
2775.73.160.0/2075.73.160.1 to 75.73.175.25475.73.175.2554,094
2875.73.176.0/2075.73.176.1 to 75.73.191.25475.73.191.2554,094
2975.73.192.0/2075.73.192.1 to 75.73.207.25475.73.207.2554,094
3075.73.208.0/2075.73.208.1 to 75.73.223.25475.73.223.2554,094
3175.73.224.0/2075.73.224.1 to 75.73.239.25475.73.239.2554,094
3275.73.240.0/2075.73.240.1 to 75.73.255.25475.73.255.2554,094
3375.74.0.0/2075.74.0.1 to 75.74.15.25475.74.15.2554,094
3475.74.16.0/2075.74.16.1 to 75.74.31.25475.74.31.2554,094
3575.74.32.0/2075.74.32.1 to 75.74.47.25475.74.47.2554,094
3675.74.48.0/2075.74.48.1 to 75.74.63.25475.74.63.2554,094
3775.74.64.0/2075.74.64.1 to 75.74.79.25475.74.79.2554,094
3875.74.80.0/2075.74.80.1 to 75.74.95.25475.74.95.2554,094
3975.74.96.0/2075.74.96.1 to 75.74.111.25475.74.111.2554,094
4075.74.112.0/2075.74.112.1 to 75.74.127.25475.74.127.2554,094
4175.74.128.0/2075.74.128.1 to 75.74.143.25475.74.143.2554,094
4275.74.144.0/2075.74.144.1 to 75.74.159.25475.74.159.2554,094
4375.74.160.0/2075.74.160.1 to 75.74.175.25475.74.175.2554,094
4475.74.176.0/2075.74.176.1 to 75.74.191.25475.74.191.2554,094
4575.74.192.0/2075.74.192.1 to 75.74.207.25475.74.207.2554,094
4675.74.208.0/2075.74.208.1 to 75.74.223.25475.74.223.2554,094
4775.74.224.0/2075.74.224.1 to 75.74.239.25475.74.239.2554,094
4875.74.240.0/2075.74.240.1 to 75.74.255.25475.74.255.2554,094
4975.75.0.0/2075.75.0.1 to 75.75.15.25475.75.15.2554,094
5075.75.16.0/2075.75.16.1 to 75.75.31.25475.75.31.2554,094
5175.75.32.0/2075.75.32.1 to 75.75.47.25475.75.47.2554,094
5275.75.48.0/2075.75.48.1 to 75.75.63.25475.75.63.2554,094
5375.75.64.0/2075.75.64.1 to 75.75.79.25475.75.79.2554,094
5475.75.80.0/2075.75.80.1 to 75.75.95.25475.75.95.2554,094
5575.75.96.0/2075.75.96.1 to 75.75.111.25475.75.111.2554,094
5675.75.112.0/2075.75.112.1 to 75.75.127.25475.75.127.2554,094
5775.75.128.0/2075.75.128.1 to 75.75.143.25475.75.143.2554,094
5875.75.144.0/2075.75.144.1 to 75.75.159.25475.75.159.2554,094
5975.75.160.0/2075.75.160.1 to 75.75.175.25475.75.175.2554,094
6075.75.176.0/2075.75.176.1 to 75.75.191.25475.75.191.2554,094
6175.75.192.0/2075.75.192.1 to 75.75.207.25475.75.207.2554,094
6275.75.208.0/2075.75.208.1 to 75.75.223.25475.75.223.2554,094
6375.75.224.0/2075.75.224.1 to 75.75.239.25475.75.239.2554,094
6475.75.240.0/2075.75.240.1 to 75.75.255.25475.75.255.2554,094
6575.76.0.0/2075.76.0.1 to 75.76.15.25475.76.15.2554,094
6675.76.16.0/2075.76.16.1 to 75.76.31.25475.76.31.2554,094
6775.76.32.0/2075.76.32.1 to 75.76.47.25475.76.47.2554,094
6875.76.48.0/2075.76.48.1 to 75.76.63.25475.76.63.2554,094
6975.76.64.0/2075.76.64.1 to 75.76.79.25475.76.79.2554,094
7075.76.80.0/2075.76.80.1 to 75.76.95.25475.76.95.2554,094
7175.76.96.0/2075.76.96.1 to 75.76.111.25475.76.111.2554,094
7275.76.112.0/2075.76.112.1 to 75.76.127.25475.76.127.2554,094
7375.76.128.0/2075.76.128.1 to 75.76.143.25475.76.143.2554,094
7475.76.144.0/2075.76.144.1 to 75.76.159.25475.76.159.2554,094
7575.76.160.0/2075.76.160.1 to 75.76.175.25475.76.175.2554,094
7675.76.176.0/2075.76.176.1 to 75.76.191.25475.76.191.2554,094
7775.76.192.0/2075.76.192.1 to 75.76.207.25475.76.207.2554,094
7875.76.208.0/2075.76.208.1 to 75.76.223.25475.76.223.2554,094
7975.76.224.0/2075.76.224.1 to 75.76.239.25475.76.239.2554,094
8075.76.240.0/2075.76.240.1 to 75.76.255.25475.76.255.2554,094
8175.77.0.0/2075.77.0.1 to 75.77.15.25475.77.15.2554,094
8275.77.16.0/2075.77.16.1 to 75.77.31.25475.77.31.2554,094
8375.77.32.0/2075.77.32.1 to 75.77.47.25475.77.47.2554,094
8475.77.48.0/2075.77.48.1 to 75.77.63.25475.77.63.2554,094
8575.77.64.0/2075.77.64.1 to 75.77.79.25475.77.79.2554,094
8675.77.80.0/2075.77.80.1 to 75.77.95.25475.77.95.2554,094
8775.77.96.0/2075.77.96.1 to 75.77.111.25475.77.111.2554,094
8875.77.112.0/2075.77.112.1 to 75.77.127.25475.77.127.2554,094
8975.77.128.0/2075.77.128.1 to 75.77.143.25475.77.143.2554,094
9075.77.144.0/2075.77.144.1 to 75.77.159.25475.77.159.2554,094
9175.77.160.0/2075.77.160.1 to 75.77.175.25475.77.175.2554,094
9275.77.176.0/2075.77.176.1 to 75.77.191.25475.77.191.2554,094
9375.77.192.0/2075.77.192.1 to 75.77.207.25475.77.207.2554,094
9475.77.208.0/2075.77.208.1 to 75.77.223.25475.77.223.2554,094
9575.77.224.0/2075.77.224.1 to 75.77.239.25475.77.239.2554,094
9675.77.240.0/2075.77.240.1 to 75.77.255.25475.77.255.2554,094
9775.78.0.0/2075.78.0.1 to 75.78.15.25475.78.15.2554,094
9875.78.16.0/2075.78.16.1 to 75.78.31.25475.78.31.2554,094
9975.78.32.0/2075.78.32.1 to 75.78.47.25475.78.47.2554,094
10075.78.48.0/2075.78.48.1 to 75.78.63.25475.78.63.2554,094
10175.78.64.0/2075.78.64.1 to 75.78.79.25475.78.79.2554,094
10275.78.80.0/2075.78.80.1 to 75.78.95.25475.78.95.2554,094
10375.78.96.0/2075.78.96.1 to 75.78.111.25475.78.111.2554,094
10475.78.112.0/2075.78.112.1 to 75.78.127.25475.78.127.2554,094
10575.78.128.0/2075.78.128.1 to 75.78.143.25475.78.143.2554,094
10675.78.144.0/2075.78.144.1 to 75.78.159.25475.78.159.2554,094
10775.78.160.0/2075.78.160.1 to 75.78.175.25475.78.175.2554,094
10875.78.176.0/2075.78.176.1 to 75.78.191.25475.78.191.2554,094
10975.78.192.0/2075.78.192.1 to 75.78.207.25475.78.207.2554,094
11075.78.208.0/2075.78.208.1 to 75.78.223.25475.78.223.2554,094
11175.78.224.0/2075.78.224.1 to 75.78.239.25475.78.239.2554,094
11275.78.240.0/2075.78.240.1 to 75.78.255.25475.78.255.2554,094
11375.79.0.0/2075.79.0.1 to 75.79.15.25475.79.15.2554,094
11475.79.16.0/2075.79.16.1 to 75.79.31.25475.79.31.2554,094
11575.79.32.0/2075.79.32.1 to 75.79.47.25475.79.47.2554,094
11675.79.48.0/2075.79.48.1 to 75.79.63.25475.79.63.2554,094
11775.79.64.0/2075.79.64.1 to 75.79.79.25475.79.79.2554,094
11875.79.80.0/2075.79.80.1 to 75.79.95.25475.79.95.2554,094
11975.79.96.0/2075.79.96.1 to 75.79.111.25475.79.111.2554,094
12075.79.112.0/2075.79.112.1 to 75.79.127.25475.79.127.2554,094
12175.79.128.0/2075.79.128.1 to 75.79.143.25475.79.143.2554,094
12275.79.144.0/2075.79.144.1 to 75.79.159.25475.79.159.2554,094
12375.79.160.0/2075.79.160.1 to 75.79.175.25475.79.175.2554,094
12475.79.176.0/2075.79.176.1 to 75.79.191.25475.79.191.2554,094
12575.79.192.0/2075.79.192.1 to 75.79.207.25475.79.207.2554,094
12675.79.208.0/2075.79.208.1 to 75.79.223.25475.79.223.2554,094
12775.79.224.0/2075.79.224.1 to 75.79.239.25475.79.239.2554,094
12875.79.240.0/2075.79.240.1 to 75.79.255.25475.79.255.2554,094

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.