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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.

Network64.0.0.0/2
Usable hosts1,073,741,822
Subnet mask192.0.0.0
Addresses1,073,741,824
Network address
64.0.0.0
Broadcast address
127.255.255.255
First usable
64.0.0.1
Last usable
127.255.255.254
Usable hosts
1,073,741,822 (1,073,741,824 less the network and broadcast addresses)
Subnet mask
192.0.0.0
Wildcard mask
63.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/2
Type
Public public
Old class
A (default /8)
As numbers
Hex 40000000 · Integer 1073741824 to 2147483647
Reverse DNS zones
64.in-addr.arpa
65.in-addr.arpa
66.in-addr.arpa
67.in-addr.arpa
68.in-addr.arpa
69.in-addr.arpa
70.in-addr.arpa
71.in-addr.arpa
72.in-addr.arpa
73.in-addr.arpa
74.in-addr.arpa
75.in-addr.arpa
76.in-addr.arpa
77.in-addr.arpa
78.in-addr.arpa
79.in-addr.arpa
and 48 more
/2 is not on a 8-bit boundary, so it takes 64 /8 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01000000.00000000.00000000.0000000064.0.0.0
Subnet mask11000000.00000000.00000000.00000000192.0.0.0
Network01000000.00000000.00000000.0000000064.0.0.0
Broadcast01111111.11111111.11111111.11111111127.255.255.255
Split into smaller subnets/9
/3 (2)/4 (4)/5 (8)/6 (16)/7 (32)/8 (64)/9 (128)/10 (256)/11 (512)/12 (1,024)/13 (2,048)/14 (4,096)

64.0.0.0/2 makes 128 subnets of /9.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
164.0.0.0/964.0.0.1 to 64.127.255.25464.127.255.2558,388,606
264.128.0.0/964.128.0.1 to 64.255.255.25464.255.255.2558,388,606
365.0.0.0/965.0.0.1 to 65.127.255.25465.127.255.2558,388,606
465.128.0.0/965.128.0.1 to 65.255.255.25465.255.255.2558,388,606
566.0.0.0/966.0.0.1 to 66.127.255.25466.127.255.2558,388,606
666.128.0.0/966.128.0.1 to 66.255.255.25466.255.255.2558,388,606
767.0.0.0/967.0.0.1 to 67.127.255.25467.127.255.2558,388,606
867.128.0.0/967.128.0.1 to 67.255.255.25467.255.255.2558,388,606
968.0.0.0/968.0.0.1 to 68.127.255.25468.127.255.2558,388,606
1068.128.0.0/968.128.0.1 to 68.255.255.25468.255.255.2558,388,606
1169.0.0.0/969.0.0.1 to 69.127.255.25469.127.255.2558,388,606
1269.128.0.0/969.128.0.1 to 69.255.255.25469.255.255.2558,388,606
1370.0.0.0/970.0.0.1 to 70.127.255.25470.127.255.2558,388,606
1470.128.0.0/970.128.0.1 to 70.255.255.25470.255.255.2558,388,606
1571.0.0.0/971.0.0.1 to 71.127.255.25471.127.255.2558,388,606
1671.128.0.0/971.128.0.1 to 71.255.255.25471.255.255.2558,388,606
1772.0.0.0/972.0.0.1 to 72.127.255.25472.127.255.2558,388,606
1872.128.0.0/972.128.0.1 to 72.255.255.25472.255.255.2558,388,606
1973.0.0.0/973.0.0.1 to 73.127.255.25473.127.255.2558,388,606
2073.128.0.0/973.128.0.1 to 73.255.255.25473.255.255.2558,388,606
2174.0.0.0/974.0.0.1 to 74.127.255.25474.127.255.2558,388,606
2274.128.0.0/974.128.0.1 to 74.255.255.25474.255.255.2558,388,606
2375.0.0.0/975.0.0.1 to 75.127.255.25475.127.255.2558,388,606
2475.128.0.0/975.128.0.1 to 75.255.255.25475.255.255.2558,388,606
2576.0.0.0/976.0.0.1 to 76.127.255.25476.127.255.2558,388,606
2676.128.0.0/976.128.0.1 to 76.255.255.25476.255.255.2558,388,606
2777.0.0.0/977.0.0.1 to 77.127.255.25477.127.255.2558,388,606
2877.128.0.0/977.128.0.1 to 77.255.255.25477.255.255.2558,388,606
2978.0.0.0/978.0.0.1 to 78.127.255.25478.127.255.2558,388,606
3078.128.0.0/978.128.0.1 to 78.255.255.25478.255.255.2558,388,606
3179.0.0.0/979.0.0.1 to 79.127.255.25479.127.255.2558,388,606
3279.128.0.0/979.128.0.1 to 79.255.255.25479.255.255.2558,388,606
3380.0.0.0/980.0.0.1 to 80.127.255.25480.127.255.2558,388,606
3480.128.0.0/980.128.0.1 to 80.255.255.25480.255.255.2558,388,606
3581.0.0.0/981.0.0.1 to 81.127.255.25481.127.255.2558,388,606
3681.128.0.0/981.128.0.1 to 81.255.255.25481.255.255.2558,388,606
3782.0.0.0/982.0.0.1 to 82.127.255.25482.127.255.2558,388,606
3882.128.0.0/982.128.0.1 to 82.255.255.25482.255.255.2558,388,606
3983.0.0.0/983.0.0.1 to 83.127.255.25483.127.255.2558,388,606
4083.128.0.0/983.128.0.1 to 83.255.255.25483.255.255.2558,388,606
4184.0.0.0/984.0.0.1 to 84.127.255.25484.127.255.2558,388,606
4284.128.0.0/984.128.0.1 to 84.255.255.25484.255.255.2558,388,606
4385.0.0.0/985.0.0.1 to 85.127.255.25485.127.255.2558,388,606
4485.128.0.0/985.128.0.1 to 85.255.255.25485.255.255.2558,388,606
4586.0.0.0/986.0.0.1 to 86.127.255.25486.127.255.2558,388,606
4686.128.0.0/986.128.0.1 to 86.255.255.25486.255.255.2558,388,606
4787.0.0.0/987.0.0.1 to 87.127.255.25487.127.255.2558,388,606
4887.128.0.0/987.128.0.1 to 87.255.255.25487.255.255.2558,388,606
4988.0.0.0/988.0.0.1 to 88.127.255.25488.127.255.2558,388,606
5088.128.0.0/988.128.0.1 to 88.255.255.25488.255.255.2558,388,606
5189.0.0.0/989.0.0.1 to 89.127.255.25489.127.255.2558,388,606
5289.128.0.0/989.128.0.1 to 89.255.255.25489.255.255.2558,388,606
5390.0.0.0/990.0.0.1 to 90.127.255.25490.127.255.2558,388,606
5490.128.0.0/990.128.0.1 to 90.255.255.25490.255.255.2558,388,606
5591.0.0.0/991.0.0.1 to 91.127.255.25491.127.255.2558,388,606
5691.128.0.0/991.128.0.1 to 91.255.255.25491.255.255.2558,388,606
5792.0.0.0/992.0.0.1 to 92.127.255.25492.127.255.2558,388,606
5892.128.0.0/992.128.0.1 to 92.255.255.25492.255.255.2558,388,606
5993.0.0.0/993.0.0.1 to 93.127.255.25493.127.255.2558,388,606
6093.128.0.0/993.128.0.1 to 93.255.255.25493.255.255.2558,388,606
6194.0.0.0/994.0.0.1 to 94.127.255.25494.127.255.2558,388,606
6294.128.0.0/994.128.0.1 to 94.255.255.25494.255.255.2558,388,606
6395.0.0.0/995.0.0.1 to 95.127.255.25495.127.255.2558,388,606
6495.128.0.0/995.128.0.1 to 95.255.255.25495.255.255.2558,388,606
6596.0.0.0/996.0.0.1 to 96.127.255.25496.127.255.2558,388,606
6696.128.0.0/996.128.0.1 to 96.255.255.25496.255.255.2558,388,606
6797.0.0.0/997.0.0.1 to 97.127.255.25497.127.255.2558,388,606
6897.128.0.0/997.128.0.1 to 97.255.255.25497.255.255.2558,388,606
6998.0.0.0/998.0.0.1 to 98.127.255.25498.127.255.2558,388,606
7098.128.0.0/998.128.0.1 to 98.255.255.25498.255.255.2558,388,606
7199.0.0.0/999.0.0.1 to 99.127.255.25499.127.255.2558,388,606
7299.128.0.0/999.128.0.1 to 99.255.255.25499.255.255.2558,388,606
73100.0.0.0/9100.0.0.1 to 100.127.255.254100.127.255.2558,388,606
74100.128.0.0/9100.128.0.1 to 100.255.255.254100.255.255.2558,388,606
75101.0.0.0/9101.0.0.1 to 101.127.255.254101.127.255.2558,388,606
76101.128.0.0/9101.128.0.1 to 101.255.255.254101.255.255.2558,388,606
77102.0.0.0/9102.0.0.1 to 102.127.255.254102.127.255.2558,388,606
78102.128.0.0/9102.128.0.1 to 102.255.255.254102.255.255.2558,388,606
79103.0.0.0/9103.0.0.1 to 103.127.255.254103.127.255.2558,388,606
80103.128.0.0/9103.128.0.1 to 103.255.255.254103.255.255.2558,388,606
81104.0.0.0/9104.0.0.1 to 104.127.255.254104.127.255.2558,388,606
82104.128.0.0/9104.128.0.1 to 104.255.255.254104.255.255.2558,388,606
83105.0.0.0/9105.0.0.1 to 105.127.255.254105.127.255.2558,388,606
84105.128.0.0/9105.128.0.1 to 105.255.255.254105.255.255.2558,388,606
85106.0.0.0/9106.0.0.1 to 106.127.255.254106.127.255.2558,388,606
86106.128.0.0/9106.128.0.1 to 106.255.255.254106.255.255.2558,388,606
87107.0.0.0/9107.0.0.1 to 107.127.255.254107.127.255.2558,388,606
88107.128.0.0/9107.128.0.1 to 107.255.255.254107.255.255.2558,388,606
89108.0.0.0/9108.0.0.1 to 108.127.255.254108.127.255.2558,388,606
90108.128.0.0/9108.128.0.1 to 108.255.255.254108.255.255.2558,388,606
91109.0.0.0/9109.0.0.1 to 109.127.255.254109.127.255.2558,388,606
92109.128.0.0/9109.128.0.1 to 109.255.255.254109.255.255.2558,388,606
93110.0.0.0/9110.0.0.1 to 110.127.255.254110.127.255.2558,388,606
94110.128.0.0/9110.128.0.1 to 110.255.255.254110.255.255.2558,388,606
95111.0.0.0/9111.0.0.1 to 111.127.255.254111.127.255.2558,388,606
96111.128.0.0/9111.128.0.1 to 111.255.255.254111.255.255.2558,388,606
97112.0.0.0/9112.0.0.1 to 112.127.255.254112.127.255.2558,388,606
98112.128.0.0/9112.128.0.1 to 112.255.255.254112.255.255.2558,388,606
99113.0.0.0/9113.0.0.1 to 113.127.255.254113.127.255.2558,388,606
100113.128.0.0/9113.128.0.1 to 113.255.255.254113.255.255.2558,388,606
101114.0.0.0/9114.0.0.1 to 114.127.255.254114.127.255.2558,388,606
102114.128.0.0/9114.128.0.1 to 114.255.255.254114.255.255.2558,388,606
103115.0.0.0/9115.0.0.1 to 115.127.255.254115.127.255.2558,388,606
104115.128.0.0/9115.128.0.1 to 115.255.255.254115.255.255.2558,388,606
105116.0.0.0/9116.0.0.1 to 116.127.255.254116.127.255.2558,388,606
106116.128.0.0/9116.128.0.1 to 116.255.255.254116.255.255.2558,388,606
107117.0.0.0/9117.0.0.1 to 117.127.255.254117.127.255.2558,388,606
108117.128.0.0/9117.128.0.1 to 117.255.255.254117.255.255.2558,388,606
109118.0.0.0/9118.0.0.1 to 118.127.255.254118.127.255.2558,388,606
110118.128.0.0/9118.128.0.1 to 118.255.255.254118.255.255.2558,388,606
111119.0.0.0/9119.0.0.1 to 119.127.255.254119.127.255.2558,388,606
112119.128.0.0/9119.128.0.1 to 119.255.255.254119.255.255.2558,388,606
113120.0.0.0/9120.0.0.1 to 120.127.255.254120.127.255.2558,388,606
114120.128.0.0/9120.128.0.1 to 120.255.255.254120.255.255.2558,388,606
115121.0.0.0/9121.0.0.1 to 121.127.255.254121.127.255.2558,388,606
116121.128.0.0/9121.128.0.1 to 121.255.255.254121.255.255.2558,388,606
117122.0.0.0/9122.0.0.1 to 122.127.255.254122.127.255.2558,388,606
118122.128.0.0/9122.128.0.1 to 122.255.255.254122.255.255.2558,388,606
119123.0.0.0/9123.0.0.1 to 123.127.255.254123.127.255.2558,388,606
120123.128.0.0/9123.128.0.1 to 123.255.255.254123.255.255.2558,388,606
121124.0.0.0/9124.0.0.1 to 124.127.255.254124.127.255.2558,388,606
122124.128.0.0/9124.128.0.1 to 124.255.255.254124.255.255.2558,388,606
123125.0.0.0/9125.0.0.1 to 125.127.255.254125.127.255.2558,388,606
124125.128.0.0/9125.128.0.1 to 125.255.255.254125.255.255.2558,388,606
125126.0.0.0/9126.0.0.1 to 126.127.255.254126.127.255.2558,388,606
126126.128.0.0/9126.128.0.1 to 126.255.255.254126.255.255.2558,388,606
127127.0.0.0/9127.0.0.1 to 127.127.255.254127.127.255.2558,388,606
128127.128.0.0/9127.128.0.1 to 127.255.255.254127.255.255.2558,388,606

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.