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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.

Network7.192.0.0/10
Usable hosts4,194,302
Subnet mask255.192.0.0
Addresses4,194,304
Network address
7.192.0.0
Broadcast address
7.255.255.255
First usable
7.192.0.1
Last usable
7.255.255.254
Usable hosts
4,194,302 (4,194,304 less the network and broadcast addresses)
Subnet mask
255.192.0.0
Wildcard mask
0.63.255.255 (Cisco ACLs, OSPF)
Prefix length
/10
Type
Public public
Old class
A (default /8)
As numbers
Hex 07C00000 · Integer 130023424 to 134217727
Reverse DNS zones
192.7.in-addr.arpa
193.7.in-addr.arpa
194.7.in-addr.arpa
195.7.in-addr.arpa
196.7.in-addr.arpa
197.7.in-addr.arpa
198.7.in-addr.arpa
199.7.in-addr.arpa
200.7.in-addr.arpa
201.7.in-addr.arpa
202.7.in-addr.arpa
203.7.in-addr.arpa
204.7.in-addr.arpa
205.7.in-addr.arpa
206.7.in-addr.arpa
207.7.in-addr.arpa
and 48 more
/10 is not on a 8-bit boundary, so it takes 64 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00000111.11000000.00000000.000000007.192.0.0
Subnet mask11111111.11000000.00000000.00000000255.192.0.0
Network00000111.11000000.00000000.000000007.192.0.0
Broadcast00000111.11111111.11111111.111111117.255.255.255
Split into smaller subnets/17
/11 (2)/12 (4)/13 (8)/14 (16)/15 (32)/16 (64)/17 (128)/18 (256)/19 (512)/20 (1,024)/21 (2,048)/22 (4,096)

7.192.0.0/10 makes 128 subnets of /17.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
17.192.0.0/177.192.0.1 to 7.192.127.2547.192.127.25532,766
27.192.128.0/177.192.128.1 to 7.192.255.2547.192.255.25532,766
37.193.0.0/177.193.0.1 to 7.193.127.2547.193.127.25532,766
47.193.128.0/177.193.128.1 to 7.193.255.2547.193.255.25532,766
57.194.0.0/177.194.0.1 to 7.194.127.2547.194.127.25532,766
67.194.128.0/177.194.128.1 to 7.194.255.2547.194.255.25532,766
77.195.0.0/177.195.0.1 to 7.195.127.2547.195.127.25532,766
87.195.128.0/177.195.128.1 to 7.195.255.2547.195.255.25532,766
97.196.0.0/177.196.0.1 to 7.196.127.2547.196.127.25532,766
107.196.128.0/177.196.128.1 to 7.196.255.2547.196.255.25532,766
117.197.0.0/177.197.0.1 to 7.197.127.2547.197.127.25532,766
127.197.128.0/177.197.128.1 to 7.197.255.2547.197.255.25532,766
137.198.0.0/177.198.0.1 to 7.198.127.2547.198.127.25532,766
147.198.128.0/177.198.128.1 to 7.198.255.2547.198.255.25532,766
157.199.0.0/177.199.0.1 to 7.199.127.2547.199.127.25532,766
167.199.128.0/177.199.128.1 to 7.199.255.2547.199.255.25532,766
177.200.0.0/177.200.0.1 to 7.200.127.2547.200.127.25532,766
187.200.128.0/177.200.128.1 to 7.200.255.2547.200.255.25532,766
197.201.0.0/177.201.0.1 to 7.201.127.2547.201.127.25532,766
207.201.128.0/177.201.128.1 to 7.201.255.2547.201.255.25532,766
217.202.0.0/177.202.0.1 to 7.202.127.2547.202.127.25532,766
227.202.128.0/177.202.128.1 to 7.202.255.2547.202.255.25532,766
237.203.0.0/177.203.0.1 to 7.203.127.2547.203.127.25532,766
247.203.128.0/177.203.128.1 to 7.203.255.2547.203.255.25532,766
257.204.0.0/177.204.0.1 to 7.204.127.2547.204.127.25532,766
267.204.128.0/177.204.128.1 to 7.204.255.2547.204.255.25532,766
277.205.0.0/177.205.0.1 to 7.205.127.2547.205.127.25532,766
287.205.128.0/177.205.128.1 to 7.205.255.2547.205.255.25532,766
297.206.0.0/177.206.0.1 to 7.206.127.2547.206.127.25532,766
307.206.128.0/177.206.128.1 to 7.206.255.2547.206.255.25532,766
317.207.0.0/177.207.0.1 to 7.207.127.2547.207.127.25532,766
327.207.128.0/177.207.128.1 to 7.207.255.2547.207.255.25532,766
337.208.0.0/177.208.0.1 to 7.208.127.2547.208.127.25532,766
347.208.128.0/177.208.128.1 to 7.208.255.2547.208.255.25532,766
357.209.0.0/177.209.0.1 to 7.209.127.2547.209.127.25532,766
367.209.128.0/177.209.128.1 to 7.209.255.2547.209.255.25532,766
377.210.0.0/177.210.0.1 to 7.210.127.2547.210.127.25532,766
387.210.128.0/177.210.128.1 to 7.210.255.2547.210.255.25532,766
397.211.0.0/177.211.0.1 to 7.211.127.2547.211.127.25532,766
407.211.128.0/177.211.128.1 to 7.211.255.2547.211.255.25532,766
417.212.0.0/177.212.0.1 to 7.212.127.2547.212.127.25532,766
427.212.128.0/177.212.128.1 to 7.212.255.2547.212.255.25532,766
437.213.0.0/177.213.0.1 to 7.213.127.2547.213.127.25532,766
447.213.128.0/177.213.128.1 to 7.213.255.2547.213.255.25532,766
457.214.0.0/177.214.0.1 to 7.214.127.2547.214.127.25532,766
467.214.128.0/177.214.128.1 to 7.214.255.2547.214.255.25532,766
477.215.0.0/177.215.0.1 to 7.215.127.2547.215.127.25532,766
487.215.128.0/177.215.128.1 to 7.215.255.2547.215.255.25532,766
497.216.0.0/177.216.0.1 to 7.216.127.2547.216.127.25532,766
507.216.128.0/177.216.128.1 to 7.216.255.2547.216.255.25532,766
517.217.0.0/177.217.0.1 to 7.217.127.2547.217.127.25532,766
527.217.128.0/177.217.128.1 to 7.217.255.2547.217.255.25532,766
537.218.0.0/177.218.0.1 to 7.218.127.2547.218.127.25532,766
547.218.128.0/177.218.128.1 to 7.218.255.2547.218.255.25532,766
557.219.0.0/177.219.0.1 to 7.219.127.2547.219.127.25532,766
567.219.128.0/177.219.128.1 to 7.219.255.2547.219.255.25532,766
577.220.0.0/177.220.0.1 to 7.220.127.2547.220.127.25532,766
587.220.128.0/177.220.128.1 to 7.220.255.2547.220.255.25532,766
597.221.0.0/177.221.0.1 to 7.221.127.2547.221.127.25532,766
607.221.128.0/177.221.128.1 to 7.221.255.2547.221.255.25532,766
617.222.0.0/177.222.0.1 to 7.222.127.2547.222.127.25532,766
627.222.128.0/177.222.128.1 to 7.222.255.2547.222.255.25532,766
637.223.0.0/177.223.0.1 to 7.223.127.2547.223.127.25532,766
647.223.128.0/177.223.128.1 to 7.223.255.2547.223.255.25532,766
657.224.0.0/177.224.0.1 to 7.224.127.2547.224.127.25532,766
667.224.128.0/177.224.128.1 to 7.224.255.2547.224.255.25532,766
677.225.0.0/177.225.0.1 to 7.225.127.2547.225.127.25532,766
687.225.128.0/177.225.128.1 to 7.225.255.2547.225.255.25532,766
697.226.0.0/177.226.0.1 to 7.226.127.2547.226.127.25532,766
707.226.128.0/177.226.128.1 to 7.226.255.2547.226.255.25532,766
717.227.0.0/177.227.0.1 to 7.227.127.2547.227.127.25532,766
727.227.128.0/177.227.128.1 to 7.227.255.2547.227.255.25532,766
737.228.0.0/177.228.0.1 to 7.228.127.2547.228.127.25532,766
747.228.128.0/177.228.128.1 to 7.228.255.2547.228.255.25532,766
757.229.0.0/177.229.0.1 to 7.229.127.2547.229.127.25532,766
767.229.128.0/177.229.128.1 to 7.229.255.2547.229.255.25532,766
777.230.0.0/177.230.0.1 to 7.230.127.2547.230.127.25532,766
787.230.128.0/177.230.128.1 to 7.230.255.2547.230.255.25532,766
797.231.0.0/177.231.0.1 to 7.231.127.2547.231.127.25532,766
807.231.128.0/177.231.128.1 to 7.231.255.2547.231.255.25532,766
817.232.0.0/177.232.0.1 to 7.232.127.2547.232.127.25532,766
827.232.128.0/177.232.128.1 to 7.232.255.2547.232.255.25532,766
837.233.0.0/177.233.0.1 to 7.233.127.2547.233.127.25532,766
847.233.128.0/177.233.128.1 to 7.233.255.2547.233.255.25532,766
857.234.0.0/177.234.0.1 to 7.234.127.2547.234.127.25532,766
867.234.128.0/177.234.128.1 to 7.234.255.2547.234.255.25532,766
877.235.0.0/177.235.0.1 to 7.235.127.2547.235.127.25532,766
887.235.128.0/177.235.128.1 to 7.235.255.2547.235.255.25532,766
897.236.0.0/177.236.0.1 to 7.236.127.2547.236.127.25532,766
907.236.128.0/177.236.128.1 to 7.236.255.2547.236.255.25532,766
917.237.0.0/177.237.0.1 to 7.237.127.2547.237.127.25532,766
927.237.128.0/177.237.128.1 to 7.237.255.2547.237.255.25532,766
937.238.0.0/177.238.0.1 to 7.238.127.2547.238.127.25532,766
947.238.128.0/177.238.128.1 to 7.238.255.2547.238.255.25532,766
957.239.0.0/177.239.0.1 to 7.239.127.2547.239.127.25532,766
967.239.128.0/177.239.128.1 to 7.239.255.2547.239.255.25532,766
977.240.0.0/177.240.0.1 to 7.240.127.2547.240.127.25532,766
987.240.128.0/177.240.128.1 to 7.240.255.2547.240.255.25532,766
997.241.0.0/177.241.0.1 to 7.241.127.2547.241.127.25532,766
1007.241.128.0/177.241.128.1 to 7.241.255.2547.241.255.25532,766
1017.242.0.0/177.242.0.1 to 7.242.127.2547.242.127.25532,766
1027.242.128.0/177.242.128.1 to 7.242.255.2547.242.255.25532,766
1037.243.0.0/177.243.0.1 to 7.243.127.2547.243.127.25532,766
1047.243.128.0/177.243.128.1 to 7.243.255.2547.243.255.25532,766
1057.244.0.0/177.244.0.1 to 7.244.127.2547.244.127.25532,766
1067.244.128.0/177.244.128.1 to 7.244.255.2547.244.255.25532,766
1077.245.0.0/177.245.0.1 to 7.245.127.2547.245.127.25532,766
1087.245.128.0/177.245.128.1 to 7.245.255.2547.245.255.25532,766
1097.246.0.0/177.246.0.1 to 7.246.127.2547.246.127.25532,766
1107.246.128.0/177.246.128.1 to 7.246.255.2547.246.255.25532,766
1117.247.0.0/177.247.0.1 to 7.247.127.2547.247.127.25532,766
1127.247.128.0/177.247.128.1 to 7.247.255.2547.247.255.25532,766
1137.248.0.0/177.248.0.1 to 7.248.127.2547.248.127.25532,766
1147.248.128.0/177.248.128.1 to 7.248.255.2547.248.255.25532,766
1157.249.0.0/177.249.0.1 to 7.249.127.2547.249.127.25532,766
1167.249.128.0/177.249.128.1 to 7.249.255.2547.249.255.25532,766
1177.250.0.0/177.250.0.1 to 7.250.127.2547.250.127.25532,766
1187.250.128.0/177.250.128.1 to 7.250.255.2547.250.255.25532,766
1197.251.0.0/177.251.0.1 to 7.251.127.2547.251.127.25532,766
1207.251.128.0/177.251.128.1 to 7.251.255.2547.251.255.25532,766
1217.252.0.0/177.252.0.1 to 7.252.127.2547.252.127.25532,766
1227.252.128.0/177.252.128.1 to 7.252.255.2547.252.255.25532,766
1237.253.0.0/177.253.0.1 to 7.253.127.2547.253.127.25532,766
1247.253.128.0/177.253.128.1 to 7.253.255.2547.253.255.25532,766
1257.254.0.0/177.254.0.1 to 7.254.127.2547.254.127.25532,766
1267.254.128.0/177.254.128.1 to 7.254.255.2547.254.255.25532,766
1277.255.0.0/177.255.0.1 to 7.255.127.2547.255.127.25532,766
1287.255.128.0/177.255.128.1 to 7.255.255.2547.255.255.25532,766

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.