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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.

Network10.0.0.0/7
Usable hosts33,554,430
Subnet mask254.0.0.0
Addresses33,554,432
Network address
10.0.0.0
Broadcast address
11.255.255.255
First usable
10.0.0.1
Last usable
11.255.255.254
Usable hosts
33,554,430 (33,554,432 less the network and broadcast addresses)
Subnet mask
254.0.0.0
Wildcard mask
1.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/7
Type
Public public
Old class
A (default /8)
As numbers
Hex 0A000000 · Integer 167772160 to 201326591
Reverse DNS zones
10.in-addr.arpa
11.in-addr.arpa
/7 is not on a 8-bit boundary, so it takes 2 /8 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00001010.00000000.00000000.0000000010.0.0.0
Subnet mask11111110.00000000.00000000.00000000254.0.0.0
Network00001010.00000000.00000000.0000000010.0.0.0
Broadcast00001011.11111111.11111111.1111111111.255.255.255
Split into smaller subnets/14
/8 (2)/9 (4)/10 (8)/11 (16)/12 (32)/13 (64)/14 (128)/15 (256)/16 (512)/17 (1,024)/18 (2,048)/19 (4,096)

10.0.0.0/7 makes 128 subnets of /14.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
110.0.0.0/1410.0.0.1 to 10.3.255.25410.3.255.255262,142
210.4.0.0/1410.4.0.1 to 10.7.255.25410.7.255.255262,142
310.8.0.0/1410.8.0.1 to 10.11.255.25410.11.255.255262,142
410.12.0.0/1410.12.0.1 to 10.15.255.25410.15.255.255262,142
510.16.0.0/1410.16.0.1 to 10.19.255.25410.19.255.255262,142
610.20.0.0/1410.20.0.1 to 10.23.255.25410.23.255.255262,142
710.24.0.0/1410.24.0.1 to 10.27.255.25410.27.255.255262,142
810.28.0.0/1410.28.0.1 to 10.31.255.25410.31.255.255262,142
910.32.0.0/1410.32.0.1 to 10.35.255.25410.35.255.255262,142
1010.36.0.0/1410.36.0.1 to 10.39.255.25410.39.255.255262,142
1110.40.0.0/1410.40.0.1 to 10.43.255.25410.43.255.255262,142
1210.44.0.0/1410.44.0.1 to 10.47.255.25410.47.255.255262,142
1310.48.0.0/1410.48.0.1 to 10.51.255.25410.51.255.255262,142
1410.52.0.0/1410.52.0.1 to 10.55.255.25410.55.255.255262,142
1510.56.0.0/1410.56.0.1 to 10.59.255.25410.59.255.255262,142
1610.60.0.0/1410.60.0.1 to 10.63.255.25410.63.255.255262,142
1710.64.0.0/1410.64.0.1 to 10.67.255.25410.67.255.255262,142
1810.68.0.0/1410.68.0.1 to 10.71.255.25410.71.255.255262,142
1910.72.0.0/1410.72.0.1 to 10.75.255.25410.75.255.255262,142
2010.76.0.0/1410.76.0.1 to 10.79.255.25410.79.255.255262,142
2110.80.0.0/1410.80.0.1 to 10.83.255.25410.83.255.255262,142
2210.84.0.0/1410.84.0.1 to 10.87.255.25410.87.255.255262,142
2310.88.0.0/1410.88.0.1 to 10.91.255.25410.91.255.255262,142
2410.92.0.0/1410.92.0.1 to 10.95.255.25410.95.255.255262,142
2510.96.0.0/1410.96.0.1 to 10.99.255.25410.99.255.255262,142
2610.100.0.0/1410.100.0.1 to 10.103.255.25410.103.255.255262,142
2710.104.0.0/1410.104.0.1 to 10.107.255.25410.107.255.255262,142
2810.108.0.0/1410.108.0.1 to 10.111.255.25410.111.255.255262,142
2910.112.0.0/1410.112.0.1 to 10.115.255.25410.115.255.255262,142
3010.116.0.0/1410.116.0.1 to 10.119.255.25410.119.255.255262,142
3110.120.0.0/1410.120.0.1 to 10.123.255.25410.123.255.255262,142
3210.124.0.0/1410.124.0.1 to 10.127.255.25410.127.255.255262,142
3310.128.0.0/1410.128.0.1 to 10.131.255.25410.131.255.255262,142
3410.132.0.0/1410.132.0.1 to 10.135.255.25410.135.255.255262,142
3510.136.0.0/1410.136.0.1 to 10.139.255.25410.139.255.255262,142
3610.140.0.0/1410.140.0.1 to 10.143.255.25410.143.255.255262,142
3710.144.0.0/1410.144.0.1 to 10.147.255.25410.147.255.255262,142
3810.148.0.0/1410.148.0.1 to 10.151.255.25410.151.255.255262,142
3910.152.0.0/1410.152.0.1 to 10.155.255.25410.155.255.255262,142
4010.156.0.0/1410.156.0.1 to 10.159.255.25410.159.255.255262,142
4110.160.0.0/1410.160.0.1 to 10.163.255.25410.163.255.255262,142
4210.164.0.0/1410.164.0.1 to 10.167.255.25410.167.255.255262,142
4310.168.0.0/1410.168.0.1 to 10.171.255.25410.171.255.255262,142
4410.172.0.0/1410.172.0.1 to 10.175.255.25410.175.255.255262,142
4510.176.0.0/1410.176.0.1 to 10.179.255.25410.179.255.255262,142
4610.180.0.0/1410.180.0.1 to 10.183.255.25410.183.255.255262,142
4710.184.0.0/1410.184.0.1 to 10.187.255.25410.187.255.255262,142
4810.188.0.0/1410.188.0.1 to 10.191.255.25410.191.255.255262,142
4910.192.0.0/1410.192.0.1 to 10.195.255.25410.195.255.255262,142
5010.196.0.0/1410.196.0.1 to 10.199.255.25410.199.255.255262,142
5110.200.0.0/1410.200.0.1 to 10.203.255.25410.203.255.255262,142
5210.204.0.0/1410.204.0.1 to 10.207.255.25410.207.255.255262,142
5310.208.0.0/1410.208.0.1 to 10.211.255.25410.211.255.255262,142
5410.212.0.0/1410.212.0.1 to 10.215.255.25410.215.255.255262,142
5510.216.0.0/1410.216.0.1 to 10.219.255.25410.219.255.255262,142
5610.220.0.0/1410.220.0.1 to 10.223.255.25410.223.255.255262,142
5710.224.0.0/1410.224.0.1 to 10.227.255.25410.227.255.255262,142
5810.228.0.0/1410.228.0.1 to 10.231.255.25410.231.255.255262,142
5910.232.0.0/1410.232.0.1 to 10.235.255.25410.235.255.255262,142
6010.236.0.0/1410.236.0.1 to 10.239.255.25410.239.255.255262,142
6110.240.0.0/1410.240.0.1 to 10.243.255.25410.243.255.255262,142
6210.244.0.0/1410.244.0.1 to 10.247.255.25410.247.255.255262,142
6310.248.0.0/1410.248.0.1 to 10.251.255.25410.251.255.255262,142
6410.252.0.0/1410.252.0.1 to 10.255.255.25410.255.255.255262,142
6511.0.0.0/1411.0.0.1 to 11.3.255.25411.3.255.255262,142
6611.4.0.0/1411.4.0.1 to 11.7.255.25411.7.255.255262,142
6711.8.0.0/1411.8.0.1 to 11.11.255.25411.11.255.255262,142
6811.12.0.0/1411.12.0.1 to 11.15.255.25411.15.255.255262,142
6911.16.0.0/1411.16.0.1 to 11.19.255.25411.19.255.255262,142
7011.20.0.0/1411.20.0.1 to 11.23.255.25411.23.255.255262,142
7111.24.0.0/1411.24.0.1 to 11.27.255.25411.27.255.255262,142
7211.28.0.0/1411.28.0.1 to 11.31.255.25411.31.255.255262,142
7311.32.0.0/1411.32.0.1 to 11.35.255.25411.35.255.255262,142
7411.36.0.0/1411.36.0.1 to 11.39.255.25411.39.255.255262,142
7511.40.0.0/1411.40.0.1 to 11.43.255.25411.43.255.255262,142
7611.44.0.0/1411.44.0.1 to 11.47.255.25411.47.255.255262,142
7711.48.0.0/1411.48.0.1 to 11.51.255.25411.51.255.255262,142
7811.52.0.0/1411.52.0.1 to 11.55.255.25411.55.255.255262,142
7911.56.0.0/1411.56.0.1 to 11.59.255.25411.59.255.255262,142
8011.60.0.0/1411.60.0.1 to 11.63.255.25411.63.255.255262,142
8111.64.0.0/1411.64.0.1 to 11.67.255.25411.67.255.255262,142
8211.68.0.0/1411.68.0.1 to 11.71.255.25411.71.255.255262,142
8311.72.0.0/1411.72.0.1 to 11.75.255.25411.75.255.255262,142
8411.76.0.0/1411.76.0.1 to 11.79.255.25411.79.255.255262,142
8511.80.0.0/1411.80.0.1 to 11.83.255.25411.83.255.255262,142
8611.84.0.0/1411.84.0.1 to 11.87.255.25411.87.255.255262,142
8711.88.0.0/1411.88.0.1 to 11.91.255.25411.91.255.255262,142
8811.92.0.0/1411.92.0.1 to 11.95.255.25411.95.255.255262,142
8911.96.0.0/1411.96.0.1 to 11.99.255.25411.99.255.255262,142
9011.100.0.0/1411.100.0.1 to 11.103.255.25411.103.255.255262,142
9111.104.0.0/1411.104.0.1 to 11.107.255.25411.107.255.255262,142
9211.108.0.0/1411.108.0.1 to 11.111.255.25411.111.255.255262,142
9311.112.0.0/1411.112.0.1 to 11.115.255.25411.115.255.255262,142
9411.116.0.0/1411.116.0.1 to 11.119.255.25411.119.255.255262,142
9511.120.0.0/1411.120.0.1 to 11.123.255.25411.123.255.255262,142
9611.124.0.0/1411.124.0.1 to 11.127.255.25411.127.255.255262,142
9711.128.0.0/1411.128.0.1 to 11.131.255.25411.131.255.255262,142
9811.132.0.0/1411.132.0.1 to 11.135.255.25411.135.255.255262,142
9911.136.0.0/1411.136.0.1 to 11.139.255.25411.139.255.255262,142
10011.140.0.0/1411.140.0.1 to 11.143.255.25411.143.255.255262,142
10111.144.0.0/1411.144.0.1 to 11.147.255.25411.147.255.255262,142
10211.148.0.0/1411.148.0.1 to 11.151.255.25411.151.255.255262,142
10311.152.0.0/1411.152.0.1 to 11.155.255.25411.155.255.255262,142
10411.156.0.0/1411.156.0.1 to 11.159.255.25411.159.255.255262,142
10511.160.0.0/1411.160.0.1 to 11.163.255.25411.163.255.255262,142
10611.164.0.0/1411.164.0.1 to 11.167.255.25411.167.255.255262,142
10711.168.0.0/1411.168.0.1 to 11.171.255.25411.171.255.255262,142
10811.172.0.0/1411.172.0.1 to 11.175.255.25411.175.255.255262,142
10911.176.0.0/1411.176.0.1 to 11.179.255.25411.179.255.255262,142
11011.180.0.0/1411.180.0.1 to 11.183.255.25411.183.255.255262,142
11111.184.0.0/1411.184.0.1 to 11.187.255.25411.187.255.255262,142
11211.188.0.0/1411.188.0.1 to 11.191.255.25411.191.255.255262,142
11311.192.0.0/1411.192.0.1 to 11.195.255.25411.195.255.255262,142
11411.196.0.0/1411.196.0.1 to 11.199.255.25411.199.255.255262,142
11511.200.0.0/1411.200.0.1 to 11.203.255.25411.203.255.255262,142
11611.204.0.0/1411.204.0.1 to 11.207.255.25411.207.255.255262,142
11711.208.0.0/1411.208.0.1 to 11.211.255.25411.211.255.255262,142
11811.212.0.0/1411.212.0.1 to 11.215.255.25411.215.255.255262,142
11911.216.0.0/1411.216.0.1 to 11.219.255.25411.219.255.255262,142
12011.220.0.0/1411.220.0.1 to 11.223.255.25411.223.255.255262,142
12111.224.0.0/1411.224.0.1 to 11.227.255.25411.227.255.255262,142
12211.228.0.0/1411.228.0.1 to 11.231.255.25411.231.255.255262,142
12311.232.0.0/1411.232.0.1 to 11.235.255.25411.235.255.255262,142
12411.236.0.0/1411.236.0.1 to 11.239.255.25411.239.255.255262,142
12511.240.0.0/1411.240.0.1 to 11.243.255.25411.243.255.255262,142
12611.244.0.0/1411.244.0.1 to 11.247.255.25411.247.255.255262,142
12711.248.0.0/1411.248.0.1 to 11.251.255.25411.251.255.255262,142
12811.252.0.0/1411.252.0.1 to 11.255.255.25411.255.255.255262,142

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.