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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.

Network29.0.0.0/15
Usable hosts131,070
Subnet mask255.254.0.0
Addresses131,072
Network address
29.0.0.0
Broadcast address
29.1.255.255
First usable
29.0.0.1
Last usable
29.1.255.254
Usable hosts
131,070 (131,072 less the network and broadcast addresses)
Subnet mask
255.254.0.0
Wildcard mask
0.1.255.255 (Cisco ACLs, OSPF)
Prefix length
/15
Type
Public public
Old class
A (default /8)
As numbers
Hex 1D000000 · Integer 486539264 to 486670335
Reverse DNS zones
0.29.in-addr.arpa
1.29.in-addr.arpa
/15 is not on a 8-bit boundary, so it takes 2 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00011101.00000000.00000000.0000000029.0.0.0
Subnet mask11111111.11111110.00000000.00000000255.254.0.0
Network00011101.00000000.00000000.0000000029.0.0.0
Broadcast00011101.00000001.11111111.1111111129.1.255.255
Split into smaller subnets/22
/16 (2)/17 (4)/18 (8)/19 (16)/20 (32)/21 (64)/22 (128)/23 (256)/24 (512)/25 (1,024)/26 (2,048)/27 (4,096)

29.0.0.0/15 makes 128 subnets of /22.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
129.0.0.0/2229.0.0.1 to 29.0.3.25429.0.3.2551,022
229.0.4.0/2229.0.4.1 to 29.0.7.25429.0.7.2551,022
329.0.8.0/2229.0.8.1 to 29.0.11.25429.0.11.2551,022
429.0.12.0/2229.0.12.1 to 29.0.15.25429.0.15.2551,022
529.0.16.0/2229.0.16.1 to 29.0.19.25429.0.19.2551,022
629.0.20.0/2229.0.20.1 to 29.0.23.25429.0.23.2551,022
729.0.24.0/2229.0.24.1 to 29.0.27.25429.0.27.2551,022
829.0.28.0/2229.0.28.1 to 29.0.31.25429.0.31.2551,022
929.0.32.0/2229.0.32.1 to 29.0.35.25429.0.35.2551,022
1029.0.36.0/2229.0.36.1 to 29.0.39.25429.0.39.2551,022
1129.0.40.0/2229.0.40.1 to 29.0.43.25429.0.43.2551,022
1229.0.44.0/2229.0.44.1 to 29.0.47.25429.0.47.2551,022
1329.0.48.0/2229.0.48.1 to 29.0.51.25429.0.51.2551,022
1429.0.52.0/2229.0.52.1 to 29.0.55.25429.0.55.2551,022
1529.0.56.0/2229.0.56.1 to 29.0.59.25429.0.59.2551,022
1629.0.60.0/2229.0.60.1 to 29.0.63.25429.0.63.2551,022
1729.0.64.0/2229.0.64.1 to 29.0.67.25429.0.67.2551,022
1829.0.68.0/2229.0.68.1 to 29.0.71.25429.0.71.2551,022
1929.0.72.0/2229.0.72.1 to 29.0.75.25429.0.75.2551,022
2029.0.76.0/2229.0.76.1 to 29.0.79.25429.0.79.2551,022
2129.0.80.0/2229.0.80.1 to 29.0.83.25429.0.83.2551,022
2229.0.84.0/2229.0.84.1 to 29.0.87.25429.0.87.2551,022
2329.0.88.0/2229.0.88.1 to 29.0.91.25429.0.91.2551,022
2429.0.92.0/2229.0.92.1 to 29.0.95.25429.0.95.2551,022
2529.0.96.0/2229.0.96.1 to 29.0.99.25429.0.99.2551,022
2629.0.100.0/2229.0.100.1 to 29.0.103.25429.0.103.2551,022
2729.0.104.0/2229.0.104.1 to 29.0.107.25429.0.107.2551,022
2829.0.108.0/2229.0.108.1 to 29.0.111.25429.0.111.2551,022
2929.0.112.0/2229.0.112.1 to 29.0.115.25429.0.115.2551,022
3029.0.116.0/2229.0.116.1 to 29.0.119.25429.0.119.2551,022
3129.0.120.0/2229.0.120.1 to 29.0.123.25429.0.123.2551,022
3229.0.124.0/2229.0.124.1 to 29.0.127.25429.0.127.2551,022
3329.0.128.0/2229.0.128.1 to 29.0.131.25429.0.131.2551,022
3429.0.132.0/2229.0.132.1 to 29.0.135.25429.0.135.2551,022
3529.0.136.0/2229.0.136.1 to 29.0.139.25429.0.139.2551,022
3629.0.140.0/2229.0.140.1 to 29.0.143.25429.0.143.2551,022
3729.0.144.0/2229.0.144.1 to 29.0.147.25429.0.147.2551,022
3829.0.148.0/2229.0.148.1 to 29.0.151.25429.0.151.2551,022
3929.0.152.0/2229.0.152.1 to 29.0.155.25429.0.155.2551,022
4029.0.156.0/2229.0.156.1 to 29.0.159.25429.0.159.2551,022
4129.0.160.0/2229.0.160.1 to 29.0.163.25429.0.163.2551,022
4229.0.164.0/2229.0.164.1 to 29.0.167.25429.0.167.2551,022
4329.0.168.0/2229.0.168.1 to 29.0.171.25429.0.171.2551,022
4429.0.172.0/2229.0.172.1 to 29.0.175.25429.0.175.2551,022
4529.0.176.0/2229.0.176.1 to 29.0.179.25429.0.179.2551,022
4629.0.180.0/2229.0.180.1 to 29.0.183.25429.0.183.2551,022
4729.0.184.0/2229.0.184.1 to 29.0.187.25429.0.187.2551,022
4829.0.188.0/2229.0.188.1 to 29.0.191.25429.0.191.2551,022
4929.0.192.0/2229.0.192.1 to 29.0.195.25429.0.195.2551,022
5029.0.196.0/2229.0.196.1 to 29.0.199.25429.0.199.2551,022
5129.0.200.0/2229.0.200.1 to 29.0.203.25429.0.203.2551,022
5229.0.204.0/2229.0.204.1 to 29.0.207.25429.0.207.2551,022
5329.0.208.0/2229.0.208.1 to 29.0.211.25429.0.211.2551,022
5429.0.212.0/2229.0.212.1 to 29.0.215.25429.0.215.2551,022
5529.0.216.0/2229.0.216.1 to 29.0.219.25429.0.219.2551,022
5629.0.220.0/2229.0.220.1 to 29.0.223.25429.0.223.2551,022
5729.0.224.0/2229.0.224.1 to 29.0.227.25429.0.227.2551,022
5829.0.228.0/2229.0.228.1 to 29.0.231.25429.0.231.2551,022
5929.0.232.0/2229.0.232.1 to 29.0.235.25429.0.235.2551,022
6029.0.236.0/2229.0.236.1 to 29.0.239.25429.0.239.2551,022
6129.0.240.0/2229.0.240.1 to 29.0.243.25429.0.243.2551,022
6229.0.244.0/2229.0.244.1 to 29.0.247.25429.0.247.2551,022
6329.0.248.0/2229.0.248.1 to 29.0.251.25429.0.251.2551,022
6429.0.252.0/2229.0.252.1 to 29.0.255.25429.0.255.2551,022
6529.1.0.0/2229.1.0.1 to 29.1.3.25429.1.3.2551,022
6629.1.4.0/2229.1.4.1 to 29.1.7.25429.1.7.2551,022
6729.1.8.0/2229.1.8.1 to 29.1.11.25429.1.11.2551,022
6829.1.12.0/2229.1.12.1 to 29.1.15.25429.1.15.2551,022
6929.1.16.0/2229.1.16.1 to 29.1.19.25429.1.19.2551,022
7029.1.20.0/2229.1.20.1 to 29.1.23.25429.1.23.2551,022
7129.1.24.0/2229.1.24.1 to 29.1.27.25429.1.27.2551,022
7229.1.28.0/2229.1.28.1 to 29.1.31.25429.1.31.2551,022
7329.1.32.0/2229.1.32.1 to 29.1.35.25429.1.35.2551,022
7429.1.36.0/2229.1.36.1 to 29.1.39.25429.1.39.2551,022
7529.1.40.0/2229.1.40.1 to 29.1.43.25429.1.43.2551,022
7629.1.44.0/2229.1.44.1 to 29.1.47.25429.1.47.2551,022
7729.1.48.0/2229.1.48.1 to 29.1.51.25429.1.51.2551,022
7829.1.52.0/2229.1.52.1 to 29.1.55.25429.1.55.2551,022
7929.1.56.0/2229.1.56.1 to 29.1.59.25429.1.59.2551,022
8029.1.60.0/2229.1.60.1 to 29.1.63.25429.1.63.2551,022
8129.1.64.0/2229.1.64.1 to 29.1.67.25429.1.67.2551,022
8229.1.68.0/2229.1.68.1 to 29.1.71.25429.1.71.2551,022
8329.1.72.0/2229.1.72.1 to 29.1.75.25429.1.75.2551,022
8429.1.76.0/2229.1.76.1 to 29.1.79.25429.1.79.2551,022
8529.1.80.0/2229.1.80.1 to 29.1.83.25429.1.83.2551,022
8629.1.84.0/2229.1.84.1 to 29.1.87.25429.1.87.2551,022
8729.1.88.0/2229.1.88.1 to 29.1.91.25429.1.91.2551,022
8829.1.92.0/2229.1.92.1 to 29.1.95.25429.1.95.2551,022
8929.1.96.0/2229.1.96.1 to 29.1.99.25429.1.99.2551,022
9029.1.100.0/2229.1.100.1 to 29.1.103.25429.1.103.2551,022
9129.1.104.0/2229.1.104.1 to 29.1.107.25429.1.107.2551,022
9229.1.108.0/2229.1.108.1 to 29.1.111.25429.1.111.2551,022
9329.1.112.0/2229.1.112.1 to 29.1.115.25429.1.115.2551,022
9429.1.116.0/2229.1.116.1 to 29.1.119.25429.1.119.2551,022
9529.1.120.0/2229.1.120.1 to 29.1.123.25429.1.123.2551,022
9629.1.124.0/2229.1.124.1 to 29.1.127.25429.1.127.2551,022
9729.1.128.0/2229.1.128.1 to 29.1.131.25429.1.131.2551,022
9829.1.132.0/2229.1.132.1 to 29.1.135.25429.1.135.2551,022
9929.1.136.0/2229.1.136.1 to 29.1.139.25429.1.139.2551,022
10029.1.140.0/2229.1.140.1 to 29.1.143.25429.1.143.2551,022
10129.1.144.0/2229.1.144.1 to 29.1.147.25429.1.147.2551,022
10229.1.148.0/2229.1.148.1 to 29.1.151.25429.1.151.2551,022
10329.1.152.0/2229.1.152.1 to 29.1.155.25429.1.155.2551,022
10429.1.156.0/2229.1.156.1 to 29.1.159.25429.1.159.2551,022
10529.1.160.0/2229.1.160.1 to 29.1.163.25429.1.163.2551,022
10629.1.164.0/2229.1.164.1 to 29.1.167.25429.1.167.2551,022
10729.1.168.0/2229.1.168.1 to 29.1.171.25429.1.171.2551,022
10829.1.172.0/2229.1.172.1 to 29.1.175.25429.1.175.2551,022
10929.1.176.0/2229.1.176.1 to 29.1.179.25429.1.179.2551,022
11029.1.180.0/2229.1.180.1 to 29.1.183.25429.1.183.2551,022
11129.1.184.0/2229.1.184.1 to 29.1.187.25429.1.187.2551,022
11229.1.188.0/2229.1.188.1 to 29.1.191.25429.1.191.2551,022
11329.1.192.0/2229.1.192.1 to 29.1.195.25429.1.195.2551,022
11429.1.196.0/2229.1.196.1 to 29.1.199.25429.1.199.2551,022
11529.1.200.0/2229.1.200.1 to 29.1.203.25429.1.203.2551,022
11629.1.204.0/2229.1.204.1 to 29.1.207.25429.1.207.2551,022
11729.1.208.0/2229.1.208.1 to 29.1.211.25429.1.211.2551,022
11829.1.212.0/2229.1.212.1 to 29.1.215.25429.1.215.2551,022
11929.1.216.0/2229.1.216.1 to 29.1.219.25429.1.219.2551,022
12029.1.220.0/2229.1.220.1 to 29.1.223.25429.1.223.2551,022
12129.1.224.0/2229.1.224.1 to 29.1.227.25429.1.227.2551,022
12229.1.228.0/2229.1.228.1 to 29.1.231.25429.1.231.2551,022
12329.1.232.0/2229.1.232.1 to 29.1.235.25429.1.235.2551,022
12429.1.236.0/2229.1.236.1 to 29.1.239.25429.1.239.2551,022
12529.1.240.0/2229.1.240.1 to 29.1.243.25429.1.243.2551,022
12629.1.244.0/2229.1.244.1 to 29.1.247.25429.1.247.2551,022
12729.1.248.0/2229.1.248.1 to 29.1.251.25429.1.251.2551,022
12829.1.252.0/2229.1.252.1 to 29.1.255.25429.1.255.2551,022

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.