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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.

Network64.0.0.0/4
Usable hosts268,435,454
Subnet mask240.0.0.0
Addresses268,435,456
Network address
64.0.0.0
Broadcast address
79.255.255.255
First usable
64.0.0.1
Last usable
79.255.255.254
Usable hosts
268,435,454 (268,435,456 less the network and broadcast addresses)
Subnet mask
240.0.0.0
Wildcard mask
15.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/4
Type
Public public
Old class
A (default /8)
As numbers
Hex 40000000 · Integer 1073741824 to 1342177279
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
/4 is not on a 8-bit boundary, so it takes 16 /8 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01000000.00000000.00000000.0000000064.0.0.0
Subnet mask11110000.00000000.00000000.00000000240.0.0.0
Network01000000.00000000.00000000.0000000064.0.0.0
Broadcast01001111.11111111.11111111.1111111179.255.255.255
Split into smaller subnets/11
/5 (2)/6 (4)/7 (8)/8 (16)/9 (32)/10 (64)/11 (128)/12 (256)/13 (512)/14 (1,024)/15 (2,048)/16 (4,096)

64.0.0.0/4 makes 128 subnets of /11.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
164.0.0.0/1164.0.0.1 to 64.31.255.25464.31.255.2552,097,150
264.32.0.0/1164.32.0.1 to 64.63.255.25464.63.255.2552,097,150
364.64.0.0/1164.64.0.1 to 64.95.255.25464.95.255.2552,097,150
464.96.0.0/1164.96.0.1 to 64.127.255.25464.127.255.2552,097,150
564.128.0.0/1164.128.0.1 to 64.159.255.25464.159.255.2552,097,150
664.160.0.0/1164.160.0.1 to 64.191.255.25464.191.255.2552,097,150
764.192.0.0/1164.192.0.1 to 64.223.255.25464.223.255.2552,097,150
864.224.0.0/1164.224.0.1 to 64.255.255.25464.255.255.2552,097,150
965.0.0.0/1165.0.0.1 to 65.31.255.25465.31.255.2552,097,150
1065.32.0.0/1165.32.0.1 to 65.63.255.25465.63.255.2552,097,150
1165.64.0.0/1165.64.0.1 to 65.95.255.25465.95.255.2552,097,150
1265.96.0.0/1165.96.0.1 to 65.127.255.25465.127.255.2552,097,150
1365.128.0.0/1165.128.0.1 to 65.159.255.25465.159.255.2552,097,150
1465.160.0.0/1165.160.0.1 to 65.191.255.25465.191.255.2552,097,150
1565.192.0.0/1165.192.0.1 to 65.223.255.25465.223.255.2552,097,150
1665.224.0.0/1165.224.0.1 to 65.255.255.25465.255.255.2552,097,150
1766.0.0.0/1166.0.0.1 to 66.31.255.25466.31.255.2552,097,150
1866.32.0.0/1166.32.0.1 to 66.63.255.25466.63.255.2552,097,150
1966.64.0.0/1166.64.0.1 to 66.95.255.25466.95.255.2552,097,150
2066.96.0.0/1166.96.0.1 to 66.127.255.25466.127.255.2552,097,150
2166.128.0.0/1166.128.0.1 to 66.159.255.25466.159.255.2552,097,150
2266.160.0.0/1166.160.0.1 to 66.191.255.25466.191.255.2552,097,150
2366.192.0.0/1166.192.0.1 to 66.223.255.25466.223.255.2552,097,150
2466.224.0.0/1166.224.0.1 to 66.255.255.25466.255.255.2552,097,150
2567.0.0.0/1167.0.0.1 to 67.31.255.25467.31.255.2552,097,150
2667.32.0.0/1167.32.0.1 to 67.63.255.25467.63.255.2552,097,150
2767.64.0.0/1167.64.0.1 to 67.95.255.25467.95.255.2552,097,150
2867.96.0.0/1167.96.0.1 to 67.127.255.25467.127.255.2552,097,150
2967.128.0.0/1167.128.0.1 to 67.159.255.25467.159.255.2552,097,150
3067.160.0.0/1167.160.0.1 to 67.191.255.25467.191.255.2552,097,150
3167.192.0.0/1167.192.0.1 to 67.223.255.25467.223.255.2552,097,150
3267.224.0.0/1167.224.0.1 to 67.255.255.25467.255.255.2552,097,150
3368.0.0.0/1168.0.0.1 to 68.31.255.25468.31.255.2552,097,150
3468.32.0.0/1168.32.0.1 to 68.63.255.25468.63.255.2552,097,150
3568.64.0.0/1168.64.0.1 to 68.95.255.25468.95.255.2552,097,150
3668.96.0.0/1168.96.0.1 to 68.127.255.25468.127.255.2552,097,150
3768.128.0.0/1168.128.0.1 to 68.159.255.25468.159.255.2552,097,150
3868.160.0.0/1168.160.0.1 to 68.191.255.25468.191.255.2552,097,150
3968.192.0.0/1168.192.0.1 to 68.223.255.25468.223.255.2552,097,150
4068.224.0.0/1168.224.0.1 to 68.255.255.25468.255.255.2552,097,150
4169.0.0.0/1169.0.0.1 to 69.31.255.25469.31.255.2552,097,150
4269.32.0.0/1169.32.0.1 to 69.63.255.25469.63.255.2552,097,150
4369.64.0.0/1169.64.0.1 to 69.95.255.25469.95.255.2552,097,150
4469.96.0.0/1169.96.0.1 to 69.127.255.25469.127.255.2552,097,150
4569.128.0.0/1169.128.0.1 to 69.159.255.25469.159.255.2552,097,150
4669.160.0.0/1169.160.0.1 to 69.191.255.25469.191.255.2552,097,150
4769.192.0.0/1169.192.0.1 to 69.223.255.25469.223.255.2552,097,150
4869.224.0.0/1169.224.0.1 to 69.255.255.25469.255.255.2552,097,150
4970.0.0.0/1170.0.0.1 to 70.31.255.25470.31.255.2552,097,150
5070.32.0.0/1170.32.0.1 to 70.63.255.25470.63.255.2552,097,150
5170.64.0.0/1170.64.0.1 to 70.95.255.25470.95.255.2552,097,150
5270.96.0.0/1170.96.0.1 to 70.127.255.25470.127.255.2552,097,150
5370.128.0.0/1170.128.0.1 to 70.159.255.25470.159.255.2552,097,150
5470.160.0.0/1170.160.0.1 to 70.191.255.25470.191.255.2552,097,150
5570.192.0.0/1170.192.0.1 to 70.223.255.25470.223.255.2552,097,150
5670.224.0.0/1170.224.0.1 to 70.255.255.25470.255.255.2552,097,150
5771.0.0.0/1171.0.0.1 to 71.31.255.25471.31.255.2552,097,150
5871.32.0.0/1171.32.0.1 to 71.63.255.25471.63.255.2552,097,150
5971.64.0.0/1171.64.0.1 to 71.95.255.25471.95.255.2552,097,150
6071.96.0.0/1171.96.0.1 to 71.127.255.25471.127.255.2552,097,150
6171.128.0.0/1171.128.0.1 to 71.159.255.25471.159.255.2552,097,150
6271.160.0.0/1171.160.0.1 to 71.191.255.25471.191.255.2552,097,150
6371.192.0.0/1171.192.0.1 to 71.223.255.25471.223.255.2552,097,150
6471.224.0.0/1171.224.0.1 to 71.255.255.25471.255.255.2552,097,150
6572.0.0.0/1172.0.0.1 to 72.31.255.25472.31.255.2552,097,150
6672.32.0.0/1172.32.0.1 to 72.63.255.25472.63.255.2552,097,150
6772.64.0.0/1172.64.0.1 to 72.95.255.25472.95.255.2552,097,150
6872.96.0.0/1172.96.0.1 to 72.127.255.25472.127.255.2552,097,150
6972.128.0.0/1172.128.0.1 to 72.159.255.25472.159.255.2552,097,150
7072.160.0.0/1172.160.0.1 to 72.191.255.25472.191.255.2552,097,150
7172.192.0.0/1172.192.0.1 to 72.223.255.25472.223.255.2552,097,150
7272.224.0.0/1172.224.0.1 to 72.255.255.25472.255.255.2552,097,150
7373.0.0.0/1173.0.0.1 to 73.31.255.25473.31.255.2552,097,150
7473.32.0.0/1173.32.0.1 to 73.63.255.25473.63.255.2552,097,150
7573.64.0.0/1173.64.0.1 to 73.95.255.25473.95.255.2552,097,150
7673.96.0.0/1173.96.0.1 to 73.127.255.25473.127.255.2552,097,150
7773.128.0.0/1173.128.0.1 to 73.159.255.25473.159.255.2552,097,150
7873.160.0.0/1173.160.0.1 to 73.191.255.25473.191.255.2552,097,150
7973.192.0.0/1173.192.0.1 to 73.223.255.25473.223.255.2552,097,150
8073.224.0.0/1173.224.0.1 to 73.255.255.25473.255.255.2552,097,150
8174.0.0.0/1174.0.0.1 to 74.31.255.25474.31.255.2552,097,150
8274.32.0.0/1174.32.0.1 to 74.63.255.25474.63.255.2552,097,150
8374.64.0.0/1174.64.0.1 to 74.95.255.25474.95.255.2552,097,150
8474.96.0.0/1174.96.0.1 to 74.127.255.25474.127.255.2552,097,150
8574.128.0.0/1174.128.0.1 to 74.159.255.25474.159.255.2552,097,150
8674.160.0.0/1174.160.0.1 to 74.191.255.25474.191.255.2552,097,150
8774.192.0.0/1174.192.0.1 to 74.223.255.25474.223.255.2552,097,150
8874.224.0.0/1174.224.0.1 to 74.255.255.25474.255.255.2552,097,150
8975.0.0.0/1175.0.0.1 to 75.31.255.25475.31.255.2552,097,150
9075.32.0.0/1175.32.0.1 to 75.63.255.25475.63.255.2552,097,150
9175.64.0.0/1175.64.0.1 to 75.95.255.25475.95.255.2552,097,150
9275.96.0.0/1175.96.0.1 to 75.127.255.25475.127.255.2552,097,150
9375.128.0.0/1175.128.0.1 to 75.159.255.25475.159.255.2552,097,150
9475.160.0.0/1175.160.0.1 to 75.191.255.25475.191.255.2552,097,150
9575.192.0.0/1175.192.0.1 to 75.223.255.25475.223.255.2552,097,150
9675.224.0.0/1175.224.0.1 to 75.255.255.25475.255.255.2552,097,150
9776.0.0.0/1176.0.0.1 to 76.31.255.25476.31.255.2552,097,150
9876.32.0.0/1176.32.0.1 to 76.63.255.25476.63.255.2552,097,150
9976.64.0.0/1176.64.0.1 to 76.95.255.25476.95.255.2552,097,150
10076.96.0.0/1176.96.0.1 to 76.127.255.25476.127.255.2552,097,150
10176.128.0.0/1176.128.0.1 to 76.159.255.25476.159.255.2552,097,150
10276.160.0.0/1176.160.0.1 to 76.191.255.25476.191.255.2552,097,150
10376.192.0.0/1176.192.0.1 to 76.223.255.25476.223.255.2552,097,150
10476.224.0.0/1176.224.0.1 to 76.255.255.25476.255.255.2552,097,150
10577.0.0.0/1177.0.0.1 to 77.31.255.25477.31.255.2552,097,150
10677.32.0.0/1177.32.0.1 to 77.63.255.25477.63.255.2552,097,150
10777.64.0.0/1177.64.0.1 to 77.95.255.25477.95.255.2552,097,150
10877.96.0.0/1177.96.0.1 to 77.127.255.25477.127.255.2552,097,150
10977.128.0.0/1177.128.0.1 to 77.159.255.25477.159.255.2552,097,150
11077.160.0.0/1177.160.0.1 to 77.191.255.25477.191.255.2552,097,150
11177.192.0.0/1177.192.0.1 to 77.223.255.25477.223.255.2552,097,150
11277.224.0.0/1177.224.0.1 to 77.255.255.25477.255.255.2552,097,150
11378.0.0.0/1178.0.0.1 to 78.31.255.25478.31.255.2552,097,150
11478.32.0.0/1178.32.0.1 to 78.63.255.25478.63.255.2552,097,150
11578.64.0.0/1178.64.0.1 to 78.95.255.25478.95.255.2552,097,150
11678.96.0.0/1178.96.0.1 to 78.127.255.25478.127.255.2552,097,150
11778.128.0.0/1178.128.0.1 to 78.159.255.25478.159.255.2552,097,150
11878.160.0.0/1178.160.0.1 to 78.191.255.25478.191.255.2552,097,150
11978.192.0.0/1178.192.0.1 to 78.223.255.25478.223.255.2552,097,150
12078.224.0.0/1178.224.0.1 to 78.255.255.25478.255.255.2552,097,150
12179.0.0.0/1179.0.0.1 to 79.31.255.25479.31.255.2552,097,150
12279.32.0.0/1179.32.0.1 to 79.63.255.25479.63.255.2552,097,150
12379.64.0.0/1179.64.0.1 to 79.95.255.25479.95.255.2552,097,150
12479.96.0.0/1179.96.0.1 to 79.127.255.25479.127.255.2552,097,150
12579.128.0.0/1179.128.0.1 to 79.159.255.25479.159.255.2552,097,150
12679.160.0.0/1179.160.0.1 to 79.191.255.25479.191.255.2552,097,150
12779.192.0.0/1179.192.0.1 to 79.223.255.25479.223.255.2552,097,150
12879.224.0.0/1179.224.0.1 to 79.255.255.25479.255.255.2552,097,150

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.