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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.

Network68.112.0.0/12
Usable hosts1,048,574
Subnet mask255.240.0.0
Addresses1,048,576
Network address
68.112.0.0
Broadcast address
68.127.255.255
First usable
68.112.0.1
Last usable
68.127.255.254
Usable hosts
1,048,574 (1,048,576 less the network and broadcast addresses)
Subnet mask
255.240.0.0
Wildcard mask
0.15.255.255 (Cisco ACLs, OSPF)
Prefix length
/12
Type
Public public
Old class
A (default /8)
As numbers
Hex 44700000 · Integer 1148190720 to 1149239295
Reverse DNS zones
112.68.in-addr.arpa
113.68.in-addr.arpa
114.68.in-addr.arpa
115.68.in-addr.arpa
116.68.in-addr.arpa
117.68.in-addr.arpa
118.68.in-addr.arpa
119.68.in-addr.arpa
120.68.in-addr.arpa
121.68.in-addr.arpa
122.68.in-addr.arpa
123.68.in-addr.arpa
124.68.in-addr.arpa
125.68.in-addr.arpa
126.68.in-addr.arpa
127.68.in-addr.arpa
/12 is not on a 8-bit boundary, so it takes 16 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01000100.01110000.00000000.0000000068.112.0.0
Subnet mask11111111.11110000.00000000.00000000255.240.0.0
Network01000100.01110000.00000000.0000000068.112.0.0
Broadcast01000100.01111111.11111111.1111111168.127.255.255
Split into smaller subnets/19
/13 (2)/14 (4)/15 (8)/16 (16)/17 (32)/18 (64)/19 (128)/20 (256)/21 (512)/22 (1,024)/23 (2,048)/24 (4,096)

68.112.0.0/12 makes 128 subnets of /19.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
168.112.0.0/1968.112.0.1 to 68.112.31.25468.112.31.2558,190
268.112.32.0/1968.112.32.1 to 68.112.63.25468.112.63.2558,190
368.112.64.0/1968.112.64.1 to 68.112.95.25468.112.95.2558,190
468.112.96.0/1968.112.96.1 to 68.112.127.25468.112.127.2558,190
568.112.128.0/1968.112.128.1 to 68.112.159.25468.112.159.2558,190
668.112.160.0/1968.112.160.1 to 68.112.191.25468.112.191.2558,190
768.112.192.0/1968.112.192.1 to 68.112.223.25468.112.223.2558,190
868.112.224.0/1968.112.224.1 to 68.112.255.25468.112.255.2558,190
968.113.0.0/1968.113.0.1 to 68.113.31.25468.113.31.2558,190
1068.113.32.0/1968.113.32.1 to 68.113.63.25468.113.63.2558,190
1168.113.64.0/1968.113.64.1 to 68.113.95.25468.113.95.2558,190
1268.113.96.0/1968.113.96.1 to 68.113.127.25468.113.127.2558,190
1368.113.128.0/1968.113.128.1 to 68.113.159.25468.113.159.2558,190
1468.113.160.0/1968.113.160.1 to 68.113.191.25468.113.191.2558,190
1568.113.192.0/1968.113.192.1 to 68.113.223.25468.113.223.2558,190
1668.113.224.0/1968.113.224.1 to 68.113.255.25468.113.255.2558,190
1768.114.0.0/1968.114.0.1 to 68.114.31.25468.114.31.2558,190
1868.114.32.0/1968.114.32.1 to 68.114.63.25468.114.63.2558,190
1968.114.64.0/1968.114.64.1 to 68.114.95.25468.114.95.2558,190
2068.114.96.0/1968.114.96.1 to 68.114.127.25468.114.127.2558,190
2168.114.128.0/1968.114.128.1 to 68.114.159.25468.114.159.2558,190
2268.114.160.0/1968.114.160.1 to 68.114.191.25468.114.191.2558,190
2368.114.192.0/1968.114.192.1 to 68.114.223.25468.114.223.2558,190
2468.114.224.0/1968.114.224.1 to 68.114.255.25468.114.255.2558,190
2568.115.0.0/1968.115.0.1 to 68.115.31.25468.115.31.2558,190
2668.115.32.0/1968.115.32.1 to 68.115.63.25468.115.63.2558,190
2768.115.64.0/1968.115.64.1 to 68.115.95.25468.115.95.2558,190
2868.115.96.0/1968.115.96.1 to 68.115.127.25468.115.127.2558,190
2968.115.128.0/1968.115.128.1 to 68.115.159.25468.115.159.2558,190
3068.115.160.0/1968.115.160.1 to 68.115.191.25468.115.191.2558,190
3168.115.192.0/1968.115.192.1 to 68.115.223.25468.115.223.2558,190
3268.115.224.0/1968.115.224.1 to 68.115.255.25468.115.255.2558,190
3368.116.0.0/1968.116.0.1 to 68.116.31.25468.116.31.2558,190
3468.116.32.0/1968.116.32.1 to 68.116.63.25468.116.63.2558,190
3568.116.64.0/1968.116.64.1 to 68.116.95.25468.116.95.2558,190
3668.116.96.0/1968.116.96.1 to 68.116.127.25468.116.127.2558,190
3768.116.128.0/1968.116.128.1 to 68.116.159.25468.116.159.2558,190
3868.116.160.0/1968.116.160.1 to 68.116.191.25468.116.191.2558,190
3968.116.192.0/1968.116.192.1 to 68.116.223.25468.116.223.2558,190
4068.116.224.0/1968.116.224.1 to 68.116.255.25468.116.255.2558,190
4168.117.0.0/1968.117.0.1 to 68.117.31.25468.117.31.2558,190
4268.117.32.0/1968.117.32.1 to 68.117.63.25468.117.63.2558,190
4368.117.64.0/1968.117.64.1 to 68.117.95.25468.117.95.2558,190
4468.117.96.0/1968.117.96.1 to 68.117.127.25468.117.127.2558,190
4568.117.128.0/1968.117.128.1 to 68.117.159.25468.117.159.2558,190
4668.117.160.0/1968.117.160.1 to 68.117.191.25468.117.191.2558,190
4768.117.192.0/1968.117.192.1 to 68.117.223.25468.117.223.2558,190
4868.117.224.0/1968.117.224.1 to 68.117.255.25468.117.255.2558,190
4968.118.0.0/1968.118.0.1 to 68.118.31.25468.118.31.2558,190
5068.118.32.0/1968.118.32.1 to 68.118.63.25468.118.63.2558,190
5168.118.64.0/1968.118.64.1 to 68.118.95.25468.118.95.2558,190
5268.118.96.0/1968.118.96.1 to 68.118.127.25468.118.127.2558,190
5368.118.128.0/1968.118.128.1 to 68.118.159.25468.118.159.2558,190
5468.118.160.0/1968.118.160.1 to 68.118.191.25468.118.191.2558,190
5568.118.192.0/1968.118.192.1 to 68.118.223.25468.118.223.2558,190
5668.118.224.0/1968.118.224.1 to 68.118.255.25468.118.255.2558,190
5768.119.0.0/1968.119.0.1 to 68.119.31.25468.119.31.2558,190
5868.119.32.0/1968.119.32.1 to 68.119.63.25468.119.63.2558,190
5968.119.64.0/1968.119.64.1 to 68.119.95.25468.119.95.2558,190
6068.119.96.0/1968.119.96.1 to 68.119.127.25468.119.127.2558,190
6168.119.128.0/1968.119.128.1 to 68.119.159.25468.119.159.2558,190
6268.119.160.0/1968.119.160.1 to 68.119.191.25468.119.191.2558,190
6368.119.192.0/1968.119.192.1 to 68.119.223.25468.119.223.2558,190
6468.119.224.0/1968.119.224.1 to 68.119.255.25468.119.255.2558,190
6568.120.0.0/1968.120.0.1 to 68.120.31.25468.120.31.2558,190
6668.120.32.0/1968.120.32.1 to 68.120.63.25468.120.63.2558,190
6768.120.64.0/1968.120.64.1 to 68.120.95.25468.120.95.2558,190
6868.120.96.0/1968.120.96.1 to 68.120.127.25468.120.127.2558,190
6968.120.128.0/1968.120.128.1 to 68.120.159.25468.120.159.2558,190
7068.120.160.0/1968.120.160.1 to 68.120.191.25468.120.191.2558,190
7168.120.192.0/1968.120.192.1 to 68.120.223.25468.120.223.2558,190
7268.120.224.0/1968.120.224.1 to 68.120.255.25468.120.255.2558,190
7368.121.0.0/1968.121.0.1 to 68.121.31.25468.121.31.2558,190
7468.121.32.0/1968.121.32.1 to 68.121.63.25468.121.63.2558,190
7568.121.64.0/1968.121.64.1 to 68.121.95.25468.121.95.2558,190
7668.121.96.0/1968.121.96.1 to 68.121.127.25468.121.127.2558,190
7768.121.128.0/1968.121.128.1 to 68.121.159.25468.121.159.2558,190
7868.121.160.0/1968.121.160.1 to 68.121.191.25468.121.191.2558,190
7968.121.192.0/1968.121.192.1 to 68.121.223.25468.121.223.2558,190
8068.121.224.0/1968.121.224.1 to 68.121.255.25468.121.255.2558,190
8168.122.0.0/1968.122.0.1 to 68.122.31.25468.122.31.2558,190
8268.122.32.0/1968.122.32.1 to 68.122.63.25468.122.63.2558,190
8368.122.64.0/1968.122.64.1 to 68.122.95.25468.122.95.2558,190
8468.122.96.0/1968.122.96.1 to 68.122.127.25468.122.127.2558,190
8568.122.128.0/1968.122.128.1 to 68.122.159.25468.122.159.2558,190
8668.122.160.0/1968.122.160.1 to 68.122.191.25468.122.191.2558,190
8768.122.192.0/1968.122.192.1 to 68.122.223.25468.122.223.2558,190
8868.122.224.0/1968.122.224.1 to 68.122.255.25468.122.255.2558,190
8968.123.0.0/1968.123.0.1 to 68.123.31.25468.123.31.2558,190
9068.123.32.0/1968.123.32.1 to 68.123.63.25468.123.63.2558,190
9168.123.64.0/1968.123.64.1 to 68.123.95.25468.123.95.2558,190
9268.123.96.0/1968.123.96.1 to 68.123.127.25468.123.127.2558,190
9368.123.128.0/1968.123.128.1 to 68.123.159.25468.123.159.2558,190
9468.123.160.0/1968.123.160.1 to 68.123.191.25468.123.191.2558,190
9568.123.192.0/1968.123.192.1 to 68.123.223.25468.123.223.2558,190
9668.123.224.0/1968.123.224.1 to 68.123.255.25468.123.255.2558,190
9768.124.0.0/1968.124.0.1 to 68.124.31.25468.124.31.2558,190
9868.124.32.0/1968.124.32.1 to 68.124.63.25468.124.63.2558,190
9968.124.64.0/1968.124.64.1 to 68.124.95.25468.124.95.2558,190
10068.124.96.0/1968.124.96.1 to 68.124.127.25468.124.127.2558,190
10168.124.128.0/1968.124.128.1 to 68.124.159.25468.124.159.2558,190
10268.124.160.0/1968.124.160.1 to 68.124.191.25468.124.191.2558,190
10368.124.192.0/1968.124.192.1 to 68.124.223.25468.124.223.2558,190
10468.124.224.0/1968.124.224.1 to 68.124.255.25468.124.255.2558,190
10568.125.0.0/1968.125.0.1 to 68.125.31.25468.125.31.2558,190
10668.125.32.0/1968.125.32.1 to 68.125.63.25468.125.63.2558,190
10768.125.64.0/1968.125.64.1 to 68.125.95.25468.125.95.2558,190
10868.125.96.0/1968.125.96.1 to 68.125.127.25468.125.127.2558,190
10968.125.128.0/1968.125.128.1 to 68.125.159.25468.125.159.2558,190
11068.125.160.0/1968.125.160.1 to 68.125.191.25468.125.191.2558,190
11168.125.192.0/1968.125.192.1 to 68.125.223.25468.125.223.2558,190
11268.125.224.0/1968.125.224.1 to 68.125.255.25468.125.255.2558,190
11368.126.0.0/1968.126.0.1 to 68.126.31.25468.126.31.2558,190
11468.126.32.0/1968.126.32.1 to 68.126.63.25468.126.63.2558,190
11568.126.64.0/1968.126.64.1 to 68.126.95.25468.126.95.2558,190
11668.126.96.0/1968.126.96.1 to 68.126.127.25468.126.127.2558,190
11768.126.128.0/1968.126.128.1 to 68.126.159.25468.126.159.2558,190
11868.126.160.0/1968.126.160.1 to 68.126.191.25468.126.191.2558,190
11968.126.192.0/1968.126.192.1 to 68.126.223.25468.126.223.2558,190
12068.126.224.0/1968.126.224.1 to 68.126.255.25468.126.255.2558,190
12168.127.0.0/1968.127.0.1 to 68.127.31.25468.127.31.2558,190
12268.127.32.0/1968.127.32.1 to 68.127.63.25468.127.63.2558,190
12368.127.64.0/1968.127.64.1 to 68.127.95.25468.127.95.2558,190
12468.127.96.0/1968.127.96.1 to 68.127.127.25468.127.127.2558,190
12568.127.128.0/1968.127.128.1 to 68.127.159.25468.127.159.2558,190
12668.127.160.0/1968.127.160.1 to 68.127.191.25468.127.191.2558,190
12768.127.192.0/1968.127.192.1 to 68.127.223.25468.127.223.2558,190
12868.127.224.0/1968.127.224.1 to 68.127.255.25468.127.255.2558,190

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.