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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.

Network12.64.0.0/11
Usable hosts2,097,150
Subnet mask255.224.0.0
Addresses2,097,152
Network address
12.64.0.0
Broadcast address
12.95.255.255
First usable
12.64.0.1
Last usable
12.95.255.254
Usable hosts
2,097,150 (2,097,152 less the network and broadcast addresses)
Subnet mask
255.224.0.0
Wildcard mask
0.31.255.255 (Cisco ACLs, OSPF)
Prefix length
/11
Type
Public public
Old class
A (default /8)
As numbers
Hex 0C400000 · Integer 205520896 to 207618047
Reverse DNS zones
64.12.in-addr.arpa
65.12.in-addr.arpa
66.12.in-addr.arpa
67.12.in-addr.arpa
68.12.in-addr.arpa
69.12.in-addr.arpa
70.12.in-addr.arpa
71.12.in-addr.arpa
72.12.in-addr.arpa
73.12.in-addr.arpa
74.12.in-addr.arpa
75.12.in-addr.arpa
76.12.in-addr.arpa
77.12.in-addr.arpa
78.12.in-addr.arpa
79.12.in-addr.arpa
and 16 more
/11 is not on a 8-bit boundary, so it takes 32 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00001100.01000000.00000000.0000000012.64.0.0
Subnet mask11111111.11100000.00000000.00000000255.224.0.0
Network00001100.01000000.00000000.0000000012.64.0.0
Broadcast00001100.01011111.11111111.1111111112.95.255.255
Split into smaller subnets/18
/12 (2)/13 (4)/14 (8)/15 (16)/16 (32)/17 (64)/18 (128)/19 (256)/20 (512)/21 (1,024)/22 (2,048)/23 (4,096)

12.64.0.0/11 makes 128 subnets of /18.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
112.64.0.0/1812.64.0.1 to 12.64.63.25412.64.63.25516,382
212.64.64.0/1812.64.64.1 to 12.64.127.25412.64.127.25516,382
312.64.128.0/1812.64.128.1 to 12.64.191.25412.64.191.25516,382
412.64.192.0/1812.64.192.1 to 12.64.255.25412.64.255.25516,382
512.65.0.0/1812.65.0.1 to 12.65.63.25412.65.63.25516,382
612.65.64.0/1812.65.64.1 to 12.65.127.25412.65.127.25516,382
712.65.128.0/1812.65.128.1 to 12.65.191.25412.65.191.25516,382
812.65.192.0/1812.65.192.1 to 12.65.255.25412.65.255.25516,382
912.66.0.0/1812.66.0.1 to 12.66.63.25412.66.63.25516,382
1012.66.64.0/1812.66.64.1 to 12.66.127.25412.66.127.25516,382
1112.66.128.0/1812.66.128.1 to 12.66.191.25412.66.191.25516,382
1212.66.192.0/1812.66.192.1 to 12.66.255.25412.66.255.25516,382
1312.67.0.0/1812.67.0.1 to 12.67.63.25412.67.63.25516,382
1412.67.64.0/1812.67.64.1 to 12.67.127.25412.67.127.25516,382
1512.67.128.0/1812.67.128.1 to 12.67.191.25412.67.191.25516,382
1612.67.192.0/1812.67.192.1 to 12.67.255.25412.67.255.25516,382
1712.68.0.0/1812.68.0.1 to 12.68.63.25412.68.63.25516,382
1812.68.64.0/1812.68.64.1 to 12.68.127.25412.68.127.25516,382
1912.68.128.0/1812.68.128.1 to 12.68.191.25412.68.191.25516,382
2012.68.192.0/1812.68.192.1 to 12.68.255.25412.68.255.25516,382
2112.69.0.0/1812.69.0.1 to 12.69.63.25412.69.63.25516,382
2212.69.64.0/1812.69.64.1 to 12.69.127.25412.69.127.25516,382
2312.69.128.0/1812.69.128.1 to 12.69.191.25412.69.191.25516,382
2412.69.192.0/1812.69.192.1 to 12.69.255.25412.69.255.25516,382
2512.70.0.0/1812.70.0.1 to 12.70.63.25412.70.63.25516,382
2612.70.64.0/1812.70.64.1 to 12.70.127.25412.70.127.25516,382
2712.70.128.0/1812.70.128.1 to 12.70.191.25412.70.191.25516,382
2812.70.192.0/1812.70.192.1 to 12.70.255.25412.70.255.25516,382
2912.71.0.0/1812.71.0.1 to 12.71.63.25412.71.63.25516,382
3012.71.64.0/1812.71.64.1 to 12.71.127.25412.71.127.25516,382
3112.71.128.0/1812.71.128.1 to 12.71.191.25412.71.191.25516,382
3212.71.192.0/1812.71.192.1 to 12.71.255.25412.71.255.25516,382
3312.72.0.0/1812.72.0.1 to 12.72.63.25412.72.63.25516,382
3412.72.64.0/1812.72.64.1 to 12.72.127.25412.72.127.25516,382
3512.72.128.0/1812.72.128.1 to 12.72.191.25412.72.191.25516,382
3612.72.192.0/1812.72.192.1 to 12.72.255.25412.72.255.25516,382
3712.73.0.0/1812.73.0.1 to 12.73.63.25412.73.63.25516,382
3812.73.64.0/1812.73.64.1 to 12.73.127.25412.73.127.25516,382
3912.73.128.0/1812.73.128.1 to 12.73.191.25412.73.191.25516,382
4012.73.192.0/1812.73.192.1 to 12.73.255.25412.73.255.25516,382
4112.74.0.0/1812.74.0.1 to 12.74.63.25412.74.63.25516,382
4212.74.64.0/1812.74.64.1 to 12.74.127.25412.74.127.25516,382
4312.74.128.0/1812.74.128.1 to 12.74.191.25412.74.191.25516,382
4412.74.192.0/1812.74.192.1 to 12.74.255.25412.74.255.25516,382
4512.75.0.0/1812.75.0.1 to 12.75.63.25412.75.63.25516,382
4612.75.64.0/1812.75.64.1 to 12.75.127.25412.75.127.25516,382
4712.75.128.0/1812.75.128.1 to 12.75.191.25412.75.191.25516,382
4812.75.192.0/1812.75.192.1 to 12.75.255.25412.75.255.25516,382
4912.76.0.0/1812.76.0.1 to 12.76.63.25412.76.63.25516,382
5012.76.64.0/1812.76.64.1 to 12.76.127.25412.76.127.25516,382
5112.76.128.0/1812.76.128.1 to 12.76.191.25412.76.191.25516,382
5212.76.192.0/1812.76.192.1 to 12.76.255.25412.76.255.25516,382
5312.77.0.0/1812.77.0.1 to 12.77.63.25412.77.63.25516,382
5412.77.64.0/1812.77.64.1 to 12.77.127.25412.77.127.25516,382
5512.77.128.0/1812.77.128.1 to 12.77.191.25412.77.191.25516,382
5612.77.192.0/1812.77.192.1 to 12.77.255.25412.77.255.25516,382
5712.78.0.0/1812.78.0.1 to 12.78.63.25412.78.63.25516,382
5812.78.64.0/1812.78.64.1 to 12.78.127.25412.78.127.25516,382
5912.78.128.0/1812.78.128.1 to 12.78.191.25412.78.191.25516,382
6012.78.192.0/1812.78.192.1 to 12.78.255.25412.78.255.25516,382
6112.79.0.0/1812.79.0.1 to 12.79.63.25412.79.63.25516,382
6212.79.64.0/1812.79.64.1 to 12.79.127.25412.79.127.25516,382
6312.79.128.0/1812.79.128.1 to 12.79.191.25412.79.191.25516,382
6412.79.192.0/1812.79.192.1 to 12.79.255.25412.79.255.25516,382
6512.80.0.0/1812.80.0.1 to 12.80.63.25412.80.63.25516,382
6612.80.64.0/1812.80.64.1 to 12.80.127.25412.80.127.25516,382
6712.80.128.0/1812.80.128.1 to 12.80.191.25412.80.191.25516,382
6812.80.192.0/1812.80.192.1 to 12.80.255.25412.80.255.25516,382
6912.81.0.0/1812.81.0.1 to 12.81.63.25412.81.63.25516,382
7012.81.64.0/1812.81.64.1 to 12.81.127.25412.81.127.25516,382
7112.81.128.0/1812.81.128.1 to 12.81.191.25412.81.191.25516,382
7212.81.192.0/1812.81.192.1 to 12.81.255.25412.81.255.25516,382
7312.82.0.0/1812.82.0.1 to 12.82.63.25412.82.63.25516,382
7412.82.64.0/1812.82.64.1 to 12.82.127.25412.82.127.25516,382
7512.82.128.0/1812.82.128.1 to 12.82.191.25412.82.191.25516,382
7612.82.192.0/1812.82.192.1 to 12.82.255.25412.82.255.25516,382
7712.83.0.0/1812.83.0.1 to 12.83.63.25412.83.63.25516,382
7812.83.64.0/1812.83.64.1 to 12.83.127.25412.83.127.25516,382
7912.83.128.0/1812.83.128.1 to 12.83.191.25412.83.191.25516,382
8012.83.192.0/1812.83.192.1 to 12.83.255.25412.83.255.25516,382
8112.84.0.0/1812.84.0.1 to 12.84.63.25412.84.63.25516,382
8212.84.64.0/1812.84.64.1 to 12.84.127.25412.84.127.25516,382
8312.84.128.0/1812.84.128.1 to 12.84.191.25412.84.191.25516,382
8412.84.192.0/1812.84.192.1 to 12.84.255.25412.84.255.25516,382
8512.85.0.0/1812.85.0.1 to 12.85.63.25412.85.63.25516,382
8612.85.64.0/1812.85.64.1 to 12.85.127.25412.85.127.25516,382
8712.85.128.0/1812.85.128.1 to 12.85.191.25412.85.191.25516,382
8812.85.192.0/1812.85.192.1 to 12.85.255.25412.85.255.25516,382
8912.86.0.0/1812.86.0.1 to 12.86.63.25412.86.63.25516,382
9012.86.64.0/1812.86.64.1 to 12.86.127.25412.86.127.25516,382
9112.86.128.0/1812.86.128.1 to 12.86.191.25412.86.191.25516,382
9212.86.192.0/1812.86.192.1 to 12.86.255.25412.86.255.25516,382
9312.87.0.0/1812.87.0.1 to 12.87.63.25412.87.63.25516,382
9412.87.64.0/1812.87.64.1 to 12.87.127.25412.87.127.25516,382
9512.87.128.0/1812.87.128.1 to 12.87.191.25412.87.191.25516,382
9612.87.192.0/1812.87.192.1 to 12.87.255.25412.87.255.25516,382
9712.88.0.0/1812.88.0.1 to 12.88.63.25412.88.63.25516,382
9812.88.64.0/1812.88.64.1 to 12.88.127.25412.88.127.25516,382
9912.88.128.0/1812.88.128.1 to 12.88.191.25412.88.191.25516,382
10012.88.192.0/1812.88.192.1 to 12.88.255.25412.88.255.25516,382
10112.89.0.0/1812.89.0.1 to 12.89.63.25412.89.63.25516,382
10212.89.64.0/1812.89.64.1 to 12.89.127.25412.89.127.25516,382
10312.89.128.0/1812.89.128.1 to 12.89.191.25412.89.191.25516,382
10412.89.192.0/1812.89.192.1 to 12.89.255.25412.89.255.25516,382
10512.90.0.0/1812.90.0.1 to 12.90.63.25412.90.63.25516,382
10612.90.64.0/1812.90.64.1 to 12.90.127.25412.90.127.25516,382
10712.90.128.0/1812.90.128.1 to 12.90.191.25412.90.191.25516,382
10812.90.192.0/1812.90.192.1 to 12.90.255.25412.90.255.25516,382
10912.91.0.0/1812.91.0.1 to 12.91.63.25412.91.63.25516,382
11012.91.64.0/1812.91.64.1 to 12.91.127.25412.91.127.25516,382
11112.91.128.0/1812.91.128.1 to 12.91.191.25412.91.191.25516,382
11212.91.192.0/1812.91.192.1 to 12.91.255.25412.91.255.25516,382
11312.92.0.0/1812.92.0.1 to 12.92.63.25412.92.63.25516,382
11412.92.64.0/1812.92.64.1 to 12.92.127.25412.92.127.25516,382
11512.92.128.0/1812.92.128.1 to 12.92.191.25412.92.191.25516,382
11612.92.192.0/1812.92.192.1 to 12.92.255.25412.92.255.25516,382
11712.93.0.0/1812.93.0.1 to 12.93.63.25412.93.63.25516,382
11812.93.64.0/1812.93.64.1 to 12.93.127.25412.93.127.25516,382
11912.93.128.0/1812.93.128.1 to 12.93.191.25412.93.191.25516,382
12012.93.192.0/1812.93.192.1 to 12.93.255.25412.93.255.25516,382
12112.94.0.0/1812.94.0.1 to 12.94.63.25412.94.63.25516,382
12212.94.64.0/1812.94.64.1 to 12.94.127.25412.94.127.25516,382
12312.94.128.0/1812.94.128.1 to 12.94.191.25412.94.191.25516,382
12412.94.192.0/1812.94.192.1 to 12.94.255.25412.94.255.25516,382
12512.95.0.0/1812.95.0.1 to 12.95.63.25412.95.63.25516,382
12612.95.64.0/1812.95.64.1 to 12.95.127.25412.95.127.25516,382
12712.95.128.0/1812.95.128.1 to 12.95.191.25412.95.191.25516,382
12812.95.192.0/1812.95.192.1 to 12.95.255.25412.95.255.25516,382

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.