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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.

Network64.0.0.0/5
Usable hosts134,217,726
Subnet mask248.0.0.0
Addresses134,217,728
Network address
64.0.0.0
Broadcast address
71.255.255.255
First usable
64.0.0.1
Last usable
71.255.255.254
Usable hosts
134,217,726 (134,217,728 less the network and broadcast addresses)
Subnet mask
248.0.0.0
Wildcard mask
7.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/5
Type
Public public
Old class
A (default /8)
As numbers
Hex 40000000 · Integer 1073741824 to 1207959551
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
/5 is not on a 8-bit boundary, so it takes 8 /8 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01000000.00000000.00000000.0000000064.0.0.0
Subnet mask11111000.00000000.00000000.00000000248.0.0.0
Network01000000.00000000.00000000.0000000064.0.0.0
Broadcast01000111.11111111.11111111.1111111171.255.255.255
Split into smaller subnets/12
/6 (2)/7 (4)/8 (8)/9 (16)/10 (32)/11 (64)/12 (128)/13 (256)/14 (512)/15 (1,024)/16 (2,048)/17 (4,096)

64.0.0.0/5 makes 128 subnets of /12.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
164.0.0.0/1264.0.0.1 to 64.15.255.25464.15.255.2551,048,574
264.16.0.0/1264.16.0.1 to 64.31.255.25464.31.255.2551,048,574
364.32.0.0/1264.32.0.1 to 64.47.255.25464.47.255.2551,048,574
464.48.0.0/1264.48.0.1 to 64.63.255.25464.63.255.2551,048,574
564.64.0.0/1264.64.0.1 to 64.79.255.25464.79.255.2551,048,574
664.80.0.0/1264.80.0.1 to 64.95.255.25464.95.255.2551,048,574
764.96.0.0/1264.96.0.1 to 64.111.255.25464.111.255.2551,048,574
864.112.0.0/1264.112.0.1 to 64.127.255.25464.127.255.2551,048,574
964.128.0.0/1264.128.0.1 to 64.143.255.25464.143.255.2551,048,574
1064.144.0.0/1264.144.0.1 to 64.159.255.25464.159.255.2551,048,574
1164.160.0.0/1264.160.0.1 to 64.175.255.25464.175.255.2551,048,574
1264.176.0.0/1264.176.0.1 to 64.191.255.25464.191.255.2551,048,574
1364.192.0.0/1264.192.0.1 to 64.207.255.25464.207.255.2551,048,574
1464.208.0.0/1264.208.0.1 to 64.223.255.25464.223.255.2551,048,574
1564.224.0.0/1264.224.0.1 to 64.239.255.25464.239.255.2551,048,574
1664.240.0.0/1264.240.0.1 to 64.255.255.25464.255.255.2551,048,574
1765.0.0.0/1265.0.0.1 to 65.15.255.25465.15.255.2551,048,574
1865.16.0.0/1265.16.0.1 to 65.31.255.25465.31.255.2551,048,574
1965.32.0.0/1265.32.0.1 to 65.47.255.25465.47.255.2551,048,574
2065.48.0.0/1265.48.0.1 to 65.63.255.25465.63.255.2551,048,574
2165.64.0.0/1265.64.0.1 to 65.79.255.25465.79.255.2551,048,574
2265.80.0.0/1265.80.0.1 to 65.95.255.25465.95.255.2551,048,574
2365.96.0.0/1265.96.0.1 to 65.111.255.25465.111.255.2551,048,574
2465.112.0.0/1265.112.0.1 to 65.127.255.25465.127.255.2551,048,574
2565.128.0.0/1265.128.0.1 to 65.143.255.25465.143.255.2551,048,574
2665.144.0.0/1265.144.0.1 to 65.159.255.25465.159.255.2551,048,574
2765.160.0.0/1265.160.0.1 to 65.175.255.25465.175.255.2551,048,574
2865.176.0.0/1265.176.0.1 to 65.191.255.25465.191.255.2551,048,574
2965.192.0.0/1265.192.0.1 to 65.207.255.25465.207.255.2551,048,574
3065.208.0.0/1265.208.0.1 to 65.223.255.25465.223.255.2551,048,574
3165.224.0.0/1265.224.0.1 to 65.239.255.25465.239.255.2551,048,574
3265.240.0.0/1265.240.0.1 to 65.255.255.25465.255.255.2551,048,574
3366.0.0.0/1266.0.0.1 to 66.15.255.25466.15.255.2551,048,574
3466.16.0.0/1266.16.0.1 to 66.31.255.25466.31.255.2551,048,574
3566.32.0.0/1266.32.0.1 to 66.47.255.25466.47.255.2551,048,574
3666.48.0.0/1266.48.0.1 to 66.63.255.25466.63.255.2551,048,574
3766.64.0.0/1266.64.0.1 to 66.79.255.25466.79.255.2551,048,574
3866.80.0.0/1266.80.0.1 to 66.95.255.25466.95.255.2551,048,574
3966.96.0.0/1266.96.0.1 to 66.111.255.25466.111.255.2551,048,574
4066.112.0.0/1266.112.0.1 to 66.127.255.25466.127.255.2551,048,574
4166.128.0.0/1266.128.0.1 to 66.143.255.25466.143.255.2551,048,574
4266.144.0.0/1266.144.0.1 to 66.159.255.25466.159.255.2551,048,574
4366.160.0.0/1266.160.0.1 to 66.175.255.25466.175.255.2551,048,574
4466.176.0.0/1266.176.0.1 to 66.191.255.25466.191.255.2551,048,574
4566.192.0.0/1266.192.0.1 to 66.207.255.25466.207.255.2551,048,574
4666.208.0.0/1266.208.0.1 to 66.223.255.25466.223.255.2551,048,574
4766.224.0.0/1266.224.0.1 to 66.239.255.25466.239.255.2551,048,574
4866.240.0.0/1266.240.0.1 to 66.255.255.25466.255.255.2551,048,574
4967.0.0.0/1267.0.0.1 to 67.15.255.25467.15.255.2551,048,574
5067.16.0.0/1267.16.0.1 to 67.31.255.25467.31.255.2551,048,574
5167.32.0.0/1267.32.0.1 to 67.47.255.25467.47.255.2551,048,574
5267.48.0.0/1267.48.0.1 to 67.63.255.25467.63.255.2551,048,574
5367.64.0.0/1267.64.0.1 to 67.79.255.25467.79.255.2551,048,574
5467.80.0.0/1267.80.0.1 to 67.95.255.25467.95.255.2551,048,574
5567.96.0.0/1267.96.0.1 to 67.111.255.25467.111.255.2551,048,574
5667.112.0.0/1267.112.0.1 to 67.127.255.25467.127.255.2551,048,574
5767.128.0.0/1267.128.0.1 to 67.143.255.25467.143.255.2551,048,574
5867.144.0.0/1267.144.0.1 to 67.159.255.25467.159.255.2551,048,574
5967.160.0.0/1267.160.0.1 to 67.175.255.25467.175.255.2551,048,574
6067.176.0.0/1267.176.0.1 to 67.191.255.25467.191.255.2551,048,574
6167.192.0.0/1267.192.0.1 to 67.207.255.25467.207.255.2551,048,574
6267.208.0.0/1267.208.0.1 to 67.223.255.25467.223.255.2551,048,574
6367.224.0.0/1267.224.0.1 to 67.239.255.25467.239.255.2551,048,574
6467.240.0.0/1267.240.0.1 to 67.255.255.25467.255.255.2551,048,574
6568.0.0.0/1268.0.0.1 to 68.15.255.25468.15.255.2551,048,574
6668.16.0.0/1268.16.0.1 to 68.31.255.25468.31.255.2551,048,574
6768.32.0.0/1268.32.0.1 to 68.47.255.25468.47.255.2551,048,574
6868.48.0.0/1268.48.0.1 to 68.63.255.25468.63.255.2551,048,574
6968.64.0.0/1268.64.0.1 to 68.79.255.25468.79.255.2551,048,574
7068.80.0.0/1268.80.0.1 to 68.95.255.25468.95.255.2551,048,574
7168.96.0.0/1268.96.0.1 to 68.111.255.25468.111.255.2551,048,574
7268.112.0.0/1268.112.0.1 to 68.127.255.25468.127.255.2551,048,574
7368.128.0.0/1268.128.0.1 to 68.143.255.25468.143.255.2551,048,574
7468.144.0.0/1268.144.0.1 to 68.159.255.25468.159.255.2551,048,574
7568.160.0.0/1268.160.0.1 to 68.175.255.25468.175.255.2551,048,574
7668.176.0.0/1268.176.0.1 to 68.191.255.25468.191.255.2551,048,574
7768.192.0.0/1268.192.0.1 to 68.207.255.25468.207.255.2551,048,574
7868.208.0.0/1268.208.0.1 to 68.223.255.25468.223.255.2551,048,574
7968.224.0.0/1268.224.0.1 to 68.239.255.25468.239.255.2551,048,574
8068.240.0.0/1268.240.0.1 to 68.255.255.25468.255.255.2551,048,574
8169.0.0.0/1269.0.0.1 to 69.15.255.25469.15.255.2551,048,574
8269.16.0.0/1269.16.0.1 to 69.31.255.25469.31.255.2551,048,574
8369.32.0.0/1269.32.0.1 to 69.47.255.25469.47.255.2551,048,574
8469.48.0.0/1269.48.0.1 to 69.63.255.25469.63.255.2551,048,574
8569.64.0.0/1269.64.0.1 to 69.79.255.25469.79.255.2551,048,574
8669.80.0.0/1269.80.0.1 to 69.95.255.25469.95.255.2551,048,574
8769.96.0.0/1269.96.0.1 to 69.111.255.25469.111.255.2551,048,574
8869.112.0.0/1269.112.0.1 to 69.127.255.25469.127.255.2551,048,574
8969.128.0.0/1269.128.0.1 to 69.143.255.25469.143.255.2551,048,574
9069.144.0.0/1269.144.0.1 to 69.159.255.25469.159.255.2551,048,574
9169.160.0.0/1269.160.0.1 to 69.175.255.25469.175.255.2551,048,574
9269.176.0.0/1269.176.0.1 to 69.191.255.25469.191.255.2551,048,574
9369.192.0.0/1269.192.0.1 to 69.207.255.25469.207.255.2551,048,574
9469.208.0.0/1269.208.0.1 to 69.223.255.25469.223.255.2551,048,574
9569.224.0.0/1269.224.0.1 to 69.239.255.25469.239.255.2551,048,574
9669.240.0.0/1269.240.0.1 to 69.255.255.25469.255.255.2551,048,574
9770.0.0.0/1270.0.0.1 to 70.15.255.25470.15.255.2551,048,574
9870.16.0.0/1270.16.0.1 to 70.31.255.25470.31.255.2551,048,574
9970.32.0.0/1270.32.0.1 to 70.47.255.25470.47.255.2551,048,574
10070.48.0.0/1270.48.0.1 to 70.63.255.25470.63.255.2551,048,574
10170.64.0.0/1270.64.0.1 to 70.79.255.25470.79.255.2551,048,574
10270.80.0.0/1270.80.0.1 to 70.95.255.25470.95.255.2551,048,574
10370.96.0.0/1270.96.0.1 to 70.111.255.25470.111.255.2551,048,574
10470.112.0.0/1270.112.0.1 to 70.127.255.25470.127.255.2551,048,574
10570.128.0.0/1270.128.0.1 to 70.143.255.25470.143.255.2551,048,574
10670.144.0.0/1270.144.0.1 to 70.159.255.25470.159.255.2551,048,574
10770.160.0.0/1270.160.0.1 to 70.175.255.25470.175.255.2551,048,574
10870.176.0.0/1270.176.0.1 to 70.191.255.25470.191.255.2551,048,574
10970.192.0.0/1270.192.0.1 to 70.207.255.25470.207.255.2551,048,574
11070.208.0.0/1270.208.0.1 to 70.223.255.25470.223.255.2551,048,574
11170.224.0.0/1270.224.0.1 to 70.239.255.25470.239.255.2551,048,574
11270.240.0.0/1270.240.0.1 to 70.255.255.25470.255.255.2551,048,574
11371.0.0.0/1271.0.0.1 to 71.15.255.25471.15.255.2551,048,574
11471.16.0.0/1271.16.0.1 to 71.31.255.25471.31.255.2551,048,574
11571.32.0.0/1271.32.0.1 to 71.47.255.25471.47.255.2551,048,574
11671.48.0.0/1271.48.0.1 to 71.63.255.25471.63.255.2551,048,574
11771.64.0.0/1271.64.0.1 to 71.79.255.25471.79.255.2551,048,574
11871.80.0.0/1271.80.0.1 to 71.95.255.25471.95.255.2551,048,574
11971.96.0.0/1271.96.0.1 to 71.111.255.25471.111.255.2551,048,574
12071.112.0.0/1271.112.0.1 to 71.127.255.25471.127.255.2551,048,574
12171.128.0.0/1271.128.0.1 to 71.143.255.25471.143.255.2551,048,574
12271.144.0.0/1271.144.0.1 to 71.159.255.25471.159.255.2551,048,574
12371.160.0.0/1271.160.0.1 to 71.175.255.25471.175.255.2551,048,574
12471.176.0.0/1271.176.0.1 to 71.191.255.25471.191.255.2551,048,574
12571.192.0.0/1271.192.0.1 to 71.207.255.25471.207.255.2551,048,574
12671.208.0.0/1271.208.0.1 to 71.223.255.25471.223.255.2551,048,574
12771.224.0.0/1271.224.0.1 to 71.239.255.25471.239.255.2551,048,574
12871.240.0.0/1271.240.0.1 to 71.255.255.25471.255.255.2551,048,574

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.