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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.

Network68.64.0.0/11
Usable hosts2,097,150
Subnet mask255.224.0.0
Addresses2,097,152
Network address
68.64.0.0
Broadcast address
68.95.255.255
First usable
68.64.0.1
Last usable
68.95.255.254
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 44400000 · Integer 1145044992 to 1147142143
Reverse DNS zones
64.68.in-addr.arpa
65.68.in-addr.arpa
66.68.in-addr.arpa
67.68.in-addr.arpa
68.68.in-addr.arpa
69.68.in-addr.arpa
70.68.in-addr.arpa
71.68.in-addr.arpa
72.68.in-addr.arpa
73.68.in-addr.arpa
74.68.in-addr.arpa
75.68.in-addr.arpa
76.68.in-addr.arpa
77.68.in-addr.arpa
78.68.in-addr.arpa
79.68.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
Address01000100.01000000.00000000.0000000068.64.0.0
Subnet mask11111111.11100000.00000000.00000000255.224.0.0
Network01000100.01000000.00000000.0000000068.64.0.0
Broadcast01000100.01011111.11111111.1111111168.95.255.255
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)

68.64.0.0/11 makes 128 subnets of /18.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
168.64.0.0/1868.64.0.1 to 68.64.63.25468.64.63.25516,382
268.64.64.0/1868.64.64.1 to 68.64.127.25468.64.127.25516,382
368.64.128.0/1868.64.128.1 to 68.64.191.25468.64.191.25516,382
468.64.192.0/1868.64.192.1 to 68.64.255.25468.64.255.25516,382
568.65.0.0/1868.65.0.1 to 68.65.63.25468.65.63.25516,382
668.65.64.0/1868.65.64.1 to 68.65.127.25468.65.127.25516,382
768.65.128.0/1868.65.128.1 to 68.65.191.25468.65.191.25516,382
868.65.192.0/1868.65.192.1 to 68.65.255.25468.65.255.25516,382
968.66.0.0/1868.66.0.1 to 68.66.63.25468.66.63.25516,382
1068.66.64.0/1868.66.64.1 to 68.66.127.25468.66.127.25516,382
1168.66.128.0/1868.66.128.1 to 68.66.191.25468.66.191.25516,382
1268.66.192.0/1868.66.192.1 to 68.66.255.25468.66.255.25516,382
1368.67.0.0/1868.67.0.1 to 68.67.63.25468.67.63.25516,382
1468.67.64.0/1868.67.64.1 to 68.67.127.25468.67.127.25516,382
1568.67.128.0/1868.67.128.1 to 68.67.191.25468.67.191.25516,382
1668.67.192.0/1868.67.192.1 to 68.67.255.25468.67.255.25516,382
1768.68.0.0/1868.68.0.1 to 68.68.63.25468.68.63.25516,382
1868.68.64.0/1868.68.64.1 to 68.68.127.25468.68.127.25516,382
1968.68.128.0/1868.68.128.1 to 68.68.191.25468.68.191.25516,382
2068.68.192.0/1868.68.192.1 to 68.68.255.25468.68.255.25516,382
2168.69.0.0/1868.69.0.1 to 68.69.63.25468.69.63.25516,382
2268.69.64.0/1868.69.64.1 to 68.69.127.25468.69.127.25516,382
2368.69.128.0/1868.69.128.1 to 68.69.191.25468.69.191.25516,382
2468.69.192.0/1868.69.192.1 to 68.69.255.25468.69.255.25516,382
2568.70.0.0/1868.70.0.1 to 68.70.63.25468.70.63.25516,382
2668.70.64.0/1868.70.64.1 to 68.70.127.25468.70.127.25516,382
2768.70.128.0/1868.70.128.1 to 68.70.191.25468.70.191.25516,382
2868.70.192.0/1868.70.192.1 to 68.70.255.25468.70.255.25516,382
2968.71.0.0/1868.71.0.1 to 68.71.63.25468.71.63.25516,382
3068.71.64.0/1868.71.64.1 to 68.71.127.25468.71.127.25516,382
3168.71.128.0/1868.71.128.1 to 68.71.191.25468.71.191.25516,382
3268.71.192.0/1868.71.192.1 to 68.71.255.25468.71.255.25516,382
3368.72.0.0/1868.72.0.1 to 68.72.63.25468.72.63.25516,382
3468.72.64.0/1868.72.64.1 to 68.72.127.25468.72.127.25516,382
3568.72.128.0/1868.72.128.1 to 68.72.191.25468.72.191.25516,382
3668.72.192.0/1868.72.192.1 to 68.72.255.25468.72.255.25516,382
3768.73.0.0/1868.73.0.1 to 68.73.63.25468.73.63.25516,382
3868.73.64.0/1868.73.64.1 to 68.73.127.25468.73.127.25516,382
3968.73.128.0/1868.73.128.1 to 68.73.191.25468.73.191.25516,382
4068.73.192.0/1868.73.192.1 to 68.73.255.25468.73.255.25516,382
4168.74.0.0/1868.74.0.1 to 68.74.63.25468.74.63.25516,382
4268.74.64.0/1868.74.64.1 to 68.74.127.25468.74.127.25516,382
4368.74.128.0/1868.74.128.1 to 68.74.191.25468.74.191.25516,382
4468.74.192.0/1868.74.192.1 to 68.74.255.25468.74.255.25516,382
4568.75.0.0/1868.75.0.1 to 68.75.63.25468.75.63.25516,382
4668.75.64.0/1868.75.64.1 to 68.75.127.25468.75.127.25516,382
4768.75.128.0/1868.75.128.1 to 68.75.191.25468.75.191.25516,382
4868.75.192.0/1868.75.192.1 to 68.75.255.25468.75.255.25516,382
4968.76.0.0/1868.76.0.1 to 68.76.63.25468.76.63.25516,382
5068.76.64.0/1868.76.64.1 to 68.76.127.25468.76.127.25516,382
5168.76.128.0/1868.76.128.1 to 68.76.191.25468.76.191.25516,382
5268.76.192.0/1868.76.192.1 to 68.76.255.25468.76.255.25516,382
5368.77.0.0/1868.77.0.1 to 68.77.63.25468.77.63.25516,382
5468.77.64.0/1868.77.64.1 to 68.77.127.25468.77.127.25516,382
5568.77.128.0/1868.77.128.1 to 68.77.191.25468.77.191.25516,382
5668.77.192.0/1868.77.192.1 to 68.77.255.25468.77.255.25516,382
5768.78.0.0/1868.78.0.1 to 68.78.63.25468.78.63.25516,382
5868.78.64.0/1868.78.64.1 to 68.78.127.25468.78.127.25516,382
5968.78.128.0/1868.78.128.1 to 68.78.191.25468.78.191.25516,382
6068.78.192.0/1868.78.192.1 to 68.78.255.25468.78.255.25516,382
6168.79.0.0/1868.79.0.1 to 68.79.63.25468.79.63.25516,382
6268.79.64.0/1868.79.64.1 to 68.79.127.25468.79.127.25516,382
6368.79.128.0/1868.79.128.1 to 68.79.191.25468.79.191.25516,382
6468.79.192.0/1868.79.192.1 to 68.79.255.25468.79.255.25516,382
6568.80.0.0/1868.80.0.1 to 68.80.63.25468.80.63.25516,382
6668.80.64.0/1868.80.64.1 to 68.80.127.25468.80.127.25516,382
6768.80.128.0/1868.80.128.1 to 68.80.191.25468.80.191.25516,382
6868.80.192.0/1868.80.192.1 to 68.80.255.25468.80.255.25516,382
6968.81.0.0/1868.81.0.1 to 68.81.63.25468.81.63.25516,382
7068.81.64.0/1868.81.64.1 to 68.81.127.25468.81.127.25516,382
7168.81.128.0/1868.81.128.1 to 68.81.191.25468.81.191.25516,382
7268.81.192.0/1868.81.192.1 to 68.81.255.25468.81.255.25516,382
7368.82.0.0/1868.82.0.1 to 68.82.63.25468.82.63.25516,382
7468.82.64.0/1868.82.64.1 to 68.82.127.25468.82.127.25516,382
7568.82.128.0/1868.82.128.1 to 68.82.191.25468.82.191.25516,382
7668.82.192.0/1868.82.192.1 to 68.82.255.25468.82.255.25516,382
7768.83.0.0/1868.83.0.1 to 68.83.63.25468.83.63.25516,382
7868.83.64.0/1868.83.64.1 to 68.83.127.25468.83.127.25516,382
7968.83.128.0/1868.83.128.1 to 68.83.191.25468.83.191.25516,382
8068.83.192.0/1868.83.192.1 to 68.83.255.25468.83.255.25516,382
8168.84.0.0/1868.84.0.1 to 68.84.63.25468.84.63.25516,382
8268.84.64.0/1868.84.64.1 to 68.84.127.25468.84.127.25516,382
8368.84.128.0/1868.84.128.1 to 68.84.191.25468.84.191.25516,382
8468.84.192.0/1868.84.192.1 to 68.84.255.25468.84.255.25516,382
8568.85.0.0/1868.85.0.1 to 68.85.63.25468.85.63.25516,382
8668.85.64.0/1868.85.64.1 to 68.85.127.25468.85.127.25516,382
8768.85.128.0/1868.85.128.1 to 68.85.191.25468.85.191.25516,382
8868.85.192.0/1868.85.192.1 to 68.85.255.25468.85.255.25516,382
8968.86.0.0/1868.86.0.1 to 68.86.63.25468.86.63.25516,382
9068.86.64.0/1868.86.64.1 to 68.86.127.25468.86.127.25516,382
9168.86.128.0/1868.86.128.1 to 68.86.191.25468.86.191.25516,382
9268.86.192.0/1868.86.192.1 to 68.86.255.25468.86.255.25516,382
9368.87.0.0/1868.87.0.1 to 68.87.63.25468.87.63.25516,382
9468.87.64.0/1868.87.64.1 to 68.87.127.25468.87.127.25516,382
9568.87.128.0/1868.87.128.1 to 68.87.191.25468.87.191.25516,382
9668.87.192.0/1868.87.192.1 to 68.87.255.25468.87.255.25516,382
9768.88.0.0/1868.88.0.1 to 68.88.63.25468.88.63.25516,382
9868.88.64.0/1868.88.64.1 to 68.88.127.25468.88.127.25516,382
9968.88.128.0/1868.88.128.1 to 68.88.191.25468.88.191.25516,382
10068.88.192.0/1868.88.192.1 to 68.88.255.25468.88.255.25516,382
10168.89.0.0/1868.89.0.1 to 68.89.63.25468.89.63.25516,382
10268.89.64.0/1868.89.64.1 to 68.89.127.25468.89.127.25516,382
10368.89.128.0/1868.89.128.1 to 68.89.191.25468.89.191.25516,382
10468.89.192.0/1868.89.192.1 to 68.89.255.25468.89.255.25516,382
10568.90.0.0/1868.90.0.1 to 68.90.63.25468.90.63.25516,382
10668.90.64.0/1868.90.64.1 to 68.90.127.25468.90.127.25516,382
10768.90.128.0/1868.90.128.1 to 68.90.191.25468.90.191.25516,382
10868.90.192.0/1868.90.192.1 to 68.90.255.25468.90.255.25516,382
10968.91.0.0/1868.91.0.1 to 68.91.63.25468.91.63.25516,382
11068.91.64.0/1868.91.64.1 to 68.91.127.25468.91.127.25516,382
11168.91.128.0/1868.91.128.1 to 68.91.191.25468.91.191.25516,382
11268.91.192.0/1868.91.192.1 to 68.91.255.25468.91.255.25516,382
11368.92.0.0/1868.92.0.1 to 68.92.63.25468.92.63.25516,382
11468.92.64.0/1868.92.64.1 to 68.92.127.25468.92.127.25516,382
11568.92.128.0/1868.92.128.1 to 68.92.191.25468.92.191.25516,382
11668.92.192.0/1868.92.192.1 to 68.92.255.25468.92.255.25516,382
11768.93.0.0/1868.93.0.1 to 68.93.63.25468.93.63.25516,382
11868.93.64.0/1868.93.64.1 to 68.93.127.25468.93.127.25516,382
11968.93.128.0/1868.93.128.1 to 68.93.191.25468.93.191.25516,382
12068.93.192.0/1868.93.192.1 to 68.93.255.25468.93.255.25516,382
12168.94.0.0/1868.94.0.1 to 68.94.63.25468.94.63.25516,382
12268.94.64.0/1868.94.64.1 to 68.94.127.25468.94.127.25516,382
12368.94.128.0/1868.94.128.1 to 68.94.191.25468.94.191.25516,382
12468.94.192.0/1868.94.192.1 to 68.94.255.25468.94.255.25516,382
12568.95.0.0/1868.95.0.1 to 68.95.63.25468.95.63.25516,382
12668.95.64.0/1868.95.64.1 to 68.95.127.25468.95.127.25516,382
12768.95.128.0/1868.95.128.1 to 68.95.191.25468.95.191.25516,382
12868.95.192.0/1868.95.192.1 to 68.95.255.25468.95.255.25516,382

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.