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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.

Network7.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
7.0.0.0
Broadcast address
7.255.255.255
First usable
7.0.0.1
Last usable
7.255.255.254
Usable hosts
16,777,214 (16,777,216 less the network and broadcast addresses)
Subnet mask
255.0.0.0
Wildcard mask
0.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/8
Type
Public public
Old class
A (default /8)
As numbers
Hex 07000000 · Integer 117440512 to 134217727
Reverse DNS zone
7.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00000111..00000000.00000000.000000007.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network00000111..00000000.00000000.000000007.0.0.0
Broadcast00000111..11111111.11111111.111111117.255.255.255
Split into smaller subnets/15
/9 (2)/10 (4)/11 (8)/12 (16)/13 (32)/14 (64)/15 (128)/16 (256)/17 (512)/18 (1,024)/19 (2,048)/20 (4,096)

7.0.0.0/8 makes 128 subnets of /15.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
17.0.0.0/157.0.0.1 to 7.1.255.2547.1.255.255131,070
27.2.0.0/157.2.0.1 to 7.3.255.2547.3.255.255131,070
37.4.0.0/157.4.0.1 to 7.5.255.2547.5.255.255131,070
47.6.0.0/157.6.0.1 to 7.7.255.2547.7.255.255131,070
57.8.0.0/157.8.0.1 to 7.9.255.2547.9.255.255131,070
67.10.0.0/157.10.0.1 to 7.11.255.2547.11.255.255131,070
77.12.0.0/157.12.0.1 to 7.13.255.2547.13.255.255131,070
87.14.0.0/157.14.0.1 to 7.15.255.2547.15.255.255131,070
97.16.0.0/157.16.0.1 to 7.17.255.2547.17.255.255131,070
107.18.0.0/157.18.0.1 to 7.19.255.2547.19.255.255131,070
117.20.0.0/157.20.0.1 to 7.21.255.2547.21.255.255131,070
127.22.0.0/157.22.0.1 to 7.23.255.2547.23.255.255131,070
137.24.0.0/157.24.0.1 to 7.25.255.2547.25.255.255131,070
147.26.0.0/157.26.0.1 to 7.27.255.2547.27.255.255131,070
157.28.0.0/157.28.0.1 to 7.29.255.2547.29.255.255131,070
167.30.0.0/157.30.0.1 to 7.31.255.2547.31.255.255131,070
177.32.0.0/157.32.0.1 to 7.33.255.2547.33.255.255131,070
187.34.0.0/157.34.0.1 to 7.35.255.2547.35.255.255131,070
197.36.0.0/157.36.0.1 to 7.37.255.2547.37.255.255131,070
207.38.0.0/157.38.0.1 to 7.39.255.2547.39.255.255131,070
217.40.0.0/157.40.0.1 to 7.41.255.2547.41.255.255131,070
227.42.0.0/157.42.0.1 to 7.43.255.2547.43.255.255131,070
237.44.0.0/157.44.0.1 to 7.45.255.2547.45.255.255131,070
247.46.0.0/157.46.0.1 to 7.47.255.2547.47.255.255131,070
257.48.0.0/157.48.0.1 to 7.49.255.2547.49.255.255131,070
267.50.0.0/157.50.0.1 to 7.51.255.2547.51.255.255131,070
277.52.0.0/157.52.0.1 to 7.53.255.2547.53.255.255131,070
287.54.0.0/157.54.0.1 to 7.55.255.2547.55.255.255131,070
297.56.0.0/157.56.0.1 to 7.57.255.2547.57.255.255131,070
307.58.0.0/157.58.0.1 to 7.59.255.2547.59.255.255131,070
317.60.0.0/157.60.0.1 to 7.61.255.2547.61.255.255131,070
327.62.0.0/157.62.0.1 to 7.63.255.2547.63.255.255131,070
337.64.0.0/157.64.0.1 to 7.65.255.2547.65.255.255131,070
347.66.0.0/157.66.0.1 to 7.67.255.2547.67.255.255131,070
357.68.0.0/157.68.0.1 to 7.69.255.2547.69.255.255131,070
367.70.0.0/157.70.0.1 to 7.71.255.2547.71.255.255131,070
377.72.0.0/157.72.0.1 to 7.73.255.2547.73.255.255131,070
387.74.0.0/157.74.0.1 to 7.75.255.2547.75.255.255131,070
397.76.0.0/157.76.0.1 to 7.77.255.2547.77.255.255131,070
407.78.0.0/157.78.0.1 to 7.79.255.2547.79.255.255131,070
417.80.0.0/157.80.0.1 to 7.81.255.2547.81.255.255131,070
427.82.0.0/157.82.0.1 to 7.83.255.2547.83.255.255131,070
437.84.0.0/157.84.0.1 to 7.85.255.2547.85.255.255131,070
447.86.0.0/157.86.0.1 to 7.87.255.2547.87.255.255131,070
457.88.0.0/157.88.0.1 to 7.89.255.2547.89.255.255131,070
467.90.0.0/157.90.0.1 to 7.91.255.2547.91.255.255131,070
477.92.0.0/157.92.0.1 to 7.93.255.2547.93.255.255131,070
487.94.0.0/157.94.0.1 to 7.95.255.2547.95.255.255131,070
497.96.0.0/157.96.0.1 to 7.97.255.2547.97.255.255131,070
507.98.0.0/157.98.0.1 to 7.99.255.2547.99.255.255131,070
517.100.0.0/157.100.0.1 to 7.101.255.2547.101.255.255131,070
527.102.0.0/157.102.0.1 to 7.103.255.2547.103.255.255131,070
537.104.0.0/157.104.0.1 to 7.105.255.2547.105.255.255131,070
547.106.0.0/157.106.0.1 to 7.107.255.2547.107.255.255131,070
557.108.0.0/157.108.0.1 to 7.109.255.2547.109.255.255131,070
567.110.0.0/157.110.0.1 to 7.111.255.2547.111.255.255131,070
577.112.0.0/157.112.0.1 to 7.113.255.2547.113.255.255131,070
587.114.0.0/157.114.0.1 to 7.115.255.2547.115.255.255131,070
597.116.0.0/157.116.0.1 to 7.117.255.2547.117.255.255131,070
607.118.0.0/157.118.0.1 to 7.119.255.2547.119.255.255131,070
617.120.0.0/157.120.0.1 to 7.121.255.2547.121.255.255131,070
627.122.0.0/157.122.0.1 to 7.123.255.2547.123.255.255131,070
637.124.0.0/157.124.0.1 to 7.125.255.2547.125.255.255131,070
647.126.0.0/157.126.0.1 to 7.127.255.2547.127.255.255131,070
657.128.0.0/157.128.0.1 to 7.129.255.2547.129.255.255131,070
667.130.0.0/157.130.0.1 to 7.131.255.2547.131.255.255131,070
677.132.0.0/157.132.0.1 to 7.133.255.2547.133.255.255131,070
687.134.0.0/157.134.0.1 to 7.135.255.2547.135.255.255131,070
697.136.0.0/157.136.0.1 to 7.137.255.2547.137.255.255131,070
707.138.0.0/157.138.0.1 to 7.139.255.2547.139.255.255131,070
717.140.0.0/157.140.0.1 to 7.141.255.2547.141.255.255131,070
727.142.0.0/157.142.0.1 to 7.143.255.2547.143.255.255131,070
737.144.0.0/157.144.0.1 to 7.145.255.2547.145.255.255131,070
747.146.0.0/157.146.0.1 to 7.147.255.2547.147.255.255131,070
757.148.0.0/157.148.0.1 to 7.149.255.2547.149.255.255131,070
767.150.0.0/157.150.0.1 to 7.151.255.2547.151.255.255131,070
777.152.0.0/157.152.0.1 to 7.153.255.2547.153.255.255131,070
787.154.0.0/157.154.0.1 to 7.155.255.2547.155.255.255131,070
797.156.0.0/157.156.0.1 to 7.157.255.2547.157.255.255131,070
807.158.0.0/157.158.0.1 to 7.159.255.2547.159.255.255131,070
817.160.0.0/157.160.0.1 to 7.161.255.2547.161.255.255131,070
827.162.0.0/157.162.0.1 to 7.163.255.2547.163.255.255131,070
837.164.0.0/157.164.0.1 to 7.165.255.2547.165.255.255131,070
847.166.0.0/157.166.0.1 to 7.167.255.2547.167.255.255131,070
857.168.0.0/157.168.0.1 to 7.169.255.2547.169.255.255131,070
867.170.0.0/157.170.0.1 to 7.171.255.2547.171.255.255131,070
877.172.0.0/157.172.0.1 to 7.173.255.2547.173.255.255131,070
887.174.0.0/157.174.0.1 to 7.175.255.2547.175.255.255131,070
897.176.0.0/157.176.0.1 to 7.177.255.2547.177.255.255131,070
907.178.0.0/157.178.0.1 to 7.179.255.2547.179.255.255131,070
917.180.0.0/157.180.0.1 to 7.181.255.2547.181.255.255131,070
927.182.0.0/157.182.0.1 to 7.183.255.2547.183.255.255131,070
937.184.0.0/157.184.0.1 to 7.185.255.2547.185.255.255131,070
947.186.0.0/157.186.0.1 to 7.187.255.2547.187.255.255131,070
957.188.0.0/157.188.0.1 to 7.189.255.2547.189.255.255131,070
967.190.0.0/157.190.0.1 to 7.191.255.2547.191.255.255131,070
977.192.0.0/157.192.0.1 to 7.193.255.2547.193.255.255131,070
987.194.0.0/157.194.0.1 to 7.195.255.2547.195.255.255131,070
997.196.0.0/157.196.0.1 to 7.197.255.2547.197.255.255131,070
1007.198.0.0/157.198.0.1 to 7.199.255.2547.199.255.255131,070
1017.200.0.0/157.200.0.1 to 7.201.255.2547.201.255.255131,070
1027.202.0.0/157.202.0.1 to 7.203.255.2547.203.255.255131,070
1037.204.0.0/157.204.0.1 to 7.205.255.2547.205.255.255131,070
1047.206.0.0/157.206.0.1 to 7.207.255.2547.207.255.255131,070
1057.208.0.0/157.208.0.1 to 7.209.255.2547.209.255.255131,070
1067.210.0.0/157.210.0.1 to 7.211.255.2547.211.255.255131,070
1077.212.0.0/157.212.0.1 to 7.213.255.2547.213.255.255131,070
1087.214.0.0/157.214.0.1 to 7.215.255.2547.215.255.255131,070
1097.216.0.0/157.216.0.1 to 7.217.255.2547.217.255.255131,070
1107.218.0.0/157.218.0.1 to 7.219.255.2547.219.255.255131,070
1117.220.0.0/157.220.0.1 to 7.221.255.2547.221.255.255131,070
1127.222.0.0/157.222.0.1 to 7.223.255.2547.223.255.255131,070
1137.224.0.0/157.224.0.1 to 7.225.255.2547.225.255.255131,070
1147.226.0.0/157.226.0.1 to 7.227.255.2547.227.255.255131,070
1157.228.0.0/157.228.0.1 to 7.229.255.2547.229.255.255131,070
1167.230.0.0/157.230.0.1 to 7.231.255.2547.231.255.255131,070
1177.232.0.0/157.232.0.1 to 7.233.255.2547.233.255.255131,070
1187.234.0.0/157.234.0.1 to 7.235.255.2547.235.255.255131,070
1197.236.0.0/157.236.0.1 to 7.237.255.2547.237.255.255131,070
1207.238.0.0/157.238.0.1 to 7.239.255.2547.239.255.255131,070
1217.240.0.0/157.240.0.1 to 7.241.255.2547.241.255.255131,070
1227.242.0.0/157.242.0.1 to 7.243.255.2547.243.255.255131,070
1237.244.0.0/157.244.0.1 to 7.245.255.2547.245.255.255131,070
1247.246.0.0/157.246.0.1 to 7.247.255.2547.247.255.255131,070
1257.248.0.0/157.248.0.1 to 7.249.255.2547.249.255.255131,070
1267.250.0.0/157.250.0.1 to 7.251.255.2547.251.255.255131,070
1277.252.0.0/157.252.0.1 to 7.253.255.2547.253.255.255131,070
1287.254.0.0/157.254.0.1 to 7.255.255.2547.255.255.255131,070

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.