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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.

Network28.134.0.0/15
Usable hosts131,070
Subnet mask255.254.0.0
Addresses131,072
Network address
28.134.0.0
Broadcast address
28.135.255.255
First usable
28.134.0.1
Last usable
28.135.255.254
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 1C860000 · Integer 478543872 to 478674943
Reverse DNS zones
134.28.in-addr.arpa
135.28.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
Address00011100.10000110.00000000.0000000028.134.0.0
Subnet mask11111111.11111110.00000000.00000000255.254.0.0
Network00011100.10000110.00000000.0000000028.134.0.0
Broadcast00011100.10000111.11111111.1111111128.135.255.255
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)

28.134.0.0/15 makes 128 subnets of /22.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
128.134.0.0/2228.134.0.1 to 28.134.3.25428.134.3.2551,022
228.134.4.0/2228.134.4.1 to 28.134.7.25428.134.7.2551,022
328.134.8.0/2228.134.8.1 to 28.134.11.25428.134.11.2551,022
428.134.12.0/2228.134.12.1 to 28.134.15.25428.134.15.2551,022
528.134.16.0/2228.134.16.1 to 28.134.19.25428.134.19.2551,022
628.134.20.0/2228.134.20.1 to 28.134.23.25428.134.23.2551,022
728.134.24.0/2228.134.24.1 to 28.134.27.25428.134.27.2551,022
828.134.28.0/2228.134.28.1 to 28.134.31.25428.134.31.2551,022
928.134.32.0/2228.134.32.1 to 28.134.35.25428.134.35.2551,022
1028.134.36.0/2228.134.36.1 to 28.134.39.25428.134.39.2551,022
1128.134.40.0/2228.134.40.1 to 28.134.43.25428.134.43.2551,022
1228.134.44.0/2228.134.44.1 to 28.134.47.25428.134.47.2551,022
1328.134.48.0/2228.134.48.1 to 28.134.51.25428.134.51.2551,022
1428.134.52.0/2228.134.52.1 to 28.134.55.25428.134.55.2551,022
1528.134.56.0/2228.134.56.1 to 28.134.59.25428.134.59.2551,022
1628.134.60.0/2228.134.60.1 to 28.134.63.25428.134.63.2551,022
1728.134.64.0/2228.134.64.1 to 28.134.67.25428.134.67.2551,022
1828.134.68.0/2228.134.68.1 to 28.134.71.25428.134.71.2551,022
1928.134.72.0/2228.134.72.1 to 28.134.75.25428.134.75.2551,022
2028.134.76.0/2228.134.76.1 to 28.134.79.25428.134.79.2551,022
2128.134.80.0/2228.134.80.1 to 28.134.83.25428.134.83.2551,022
2228.134.84.0/2228.134.84.1 to 28.134.87.25428.134.87.2551,022
2328.134.88.0/2228.134.88.1 to 28.134.91.25428.134.91.2551,022
2428.134.92.0/2228.134.92.1 to 28.134.95.25428.134.95.2551,022
2528.134.96.0/2228.134.96.1 to 28.134.99.25428.134.99.2551,022
2628.134.100.0/2228.134.100.1 to 28.134.103.25428.134.103.2551,022
2728.134.104.0/2228.134.104.1 to 28.134.107.25428.134.107.2551,022
2828.134.108.0/2228.134.108.1 to 28.134.111.25428.134.111.2551,022
2928.134.112.0/2228.134.112.1 to 28.134.115.25428.134.115.2551,022
3028.134.116.0/2228.134.116.1 to 28.134.119.25428.134.119.2551,022
3128.134.120.0/2228.134.120.1 to 28.134.123.25428.134.123.2551,022
3228.134.124.0/2228.134.124.1 to 28.134.127.25428.134.127.2551,022
3328.134.128.0/2228.134.128.1 to 28.134.131.25428.134.131.2551,022
3428.134.132.0/2228.134.132.1 to 28.134.135.25428.134.135.2551,022
3528.134.136.0/2228.134.136.1 to 28.134.139.25428.134.139.2551,022
3628.134.140.0/2228.134.140.1 to 28.134.143.25428.134.143.2551,022
3728.134.144.0/2228.134.144.1 to 28.134.147.25428.134.147.2551,022
3828.134.148.0/2228.134.148.1 to 28.134.151.25428.134.151.2551,022
3928.134.152.0/2228.134.152.1 to 28.134.155.25428.134.155.2551,022
4028.134.156.0/2228.134.156.1 to 28.134.159.25428.134.159.2551,022
4128.134.160.0/2228.134.160.1 to 28.134.163.25428.134.163.2551,022
4228.134.164.0/2228.134.164.1 to 28.134.167.25428.134.167.2551,022
4328.134.168.0/2228.134.168.1 to 28.134.171.25428.134.171.2551,022
4428.134.172.0/2228.134.172.1 to 28.134.175.25428.134.175.2551,022
4528.134.176.0/2228.134.176.1 to 28.134.179.25428.134.179.2551,022
4628.134.180.0/2228.134.180.1 to 28.134.183.25428.134.183.2551,022
4728.134.184.0/2228.134.184.1 to 28.134.187.25428.134.187.2551,022
4828.134.188.0/2228.134.188.1 to 28.134.191.25428.134.191.2551,022
4928.134.192.0/2228.134.192.1 to 28.134.195.25428.134.195.2551,022
5028.134.196.0/2228.134.196.1 to 28.134.199.25428.134.199.2551,022
5128.134.200.0/2228.134.200.1 to 28.134.203.25428.134.203.2551,022
5228.134.204.0/2228.134.204.1 to 28.134.207.25428.134.207.2551,022
5328.134.208.0/2228.134.208.1 to 28.134.211.25428.134.211.2551,022
5428.134.212.0/2228.134.212.1 to 28.134.215.25428.134.215.2551,022
5528.134.216.0/2228.134.216.1 to 28.134.219.25428.134.219.2551,022
5628.134.220.0/2228.134.220.1 to 28.134.223.25428.134.223.2551,022
5728.134.224.0/2228.134.224.1 to 28.134.227.25428.134.227.2551,022
5828.134.228.0/2228.134.228.1 to 28.134.231.25428.134.231.2551,022
5928.134.232.0/2228.134.232.1 to 28.134.235.25428.134.235.2551,022
6028.134.236.0/2228.134.236.1 to 28.134.239.25428.134.239.2551,022
6128.134.240.0/2228.134.240.1 to 28.134.243.25428.134.243.2551,022
6228.134.244.0/2228.134.244.1 to 28.134.247.25428.134.247.2551,022
6328.134.248.0/2228.134.248.1 to 28.134.251.25428.134.251.2551,022
6428.134.252.0/2228.134.252.1 to 28.134.255.25428.134.255.2551,022
6528.135.0.0/2228.135.0.1 to 28.135.3.25428.135.3.2551,022
6628.135.4.0/2228.135.4.1 to 28.135.7.25428.135.7.2551,022
6728.135.8.0/2228.135.8.1 to 28.135.11.25428.135.11.2551,022
6828.135.12.0/2228.135.12.1 to 28.135.15.25428.135.15.2551,022
6928.135.16.0/2228.135.16.1 to 28.135.19.25428.135.19.2551,022
7028.135.20.0/2228.135.20.1 to 28.135.23.25428.135.23.2551,022
7128.135.24.0/2228.135.24.1 to 28.135.27.25428.135.27.2551,022
7228.135.28.0/2228.135.28.1 to 28.135.31.25428.135.31.2551,022
7328.135.32.0/2228.135.32.1 to 28.135.35.25428.135.35.2551,022
7428.135.36.0/2228.135.36.1 to 28.135.39.25428.135.39.2551,022
7528.135.40.0/2228.135.40.1 to 28.135.43.25428.135.43.2551,022
7628.135.44.0/2228.135.44.1 to 28.135.47.25428.135.47.2551,022
7728.135.48.0/2228.135.48.1 to 28.135.51.25428.135.51.2551,022
7828.135.52.0/2228.135.52.1 to 28.135.55.25428.135.55.2551,022
7928.135.56.0/2228.135.56.1 to 28.135.59.25428.135.59.2551,022
8028.135.60.0/2228.135.60.1 to 28.135.63.25428.135.63.2551,022
8128.135.64.0/2228.135.64.1 to 28.135.67.25428.135.67.2551,022
8228.135.68.0/2228.135.68.1 to 28.135.71.25428.135.71.2551,022
8328.135.72.0/2228.135.72.1 to 28.135.75.25428.135.75.2551,022
8428.135.76.0/2228.135.76.1 to 28.135.79.25428.135.79.2551,022
8528.135.80.0/2228.135.80.1 to 28.135.83.25428.135.83.2551,022
8628.135.84.0/2228.135.84.1 to 28.135.87.25428.135.87.2551,022
8728.135.88.0/2228.135.88.1 to 28.135.91.25428.135.91.2551,022
8828.135.92.0/2228.135.92.1 to 28.135.95.25428.135.95.2551,022
8928.135.96.0/2228.135.96.1 to 28.135.99.25428.135.99.2551,022
9028.135.100.0/2228.135.100.1 to 28.135.103.25428.135.103.2551,022
9128.135.104.0/2228.135.104.1 to 28.135.107.25428.135.107.2551,022
9228.135.108.0/2228.135.108.1 to 28.135.111.25428.135.111.2551,022
9328.135.112.0/2228.135.112.1 to 28.135.115.25428.135.115.2551,022
9428.135.116.0/2228.135.116.1 to 28.135.119.25428.135.119.2551,022
9528.135.120.0/2228.135.120.1 to 28.135.123.25428.135.123.2551,022
9628.135.124.0/2228.135.124.1 to 28.135.127.25428.135.127.2551,022
9728.135.128.0/2228.135.128.1 to 28.135.131.25428.135.131.2551,022
9828.135.132.0/2228.135.132.1 to 28.135.135.25428.135.135.2551,022
9928.135.136.0/2228.135.136.1 to 28.135.139.25428.135.139.2551,022
10028.135.140.0/2228.135.140.1 to 28.135.143.25428.135.143.2551,022
10128.135.144.0/2228.135.144.1 to 28.135.147.25428.135.147.2551,022
10228.135.148.0/2228.135.148.1 to 28.135.151.25428.135.151.2551,022
10328.135.152.0/2228.135.152.1 to 28.135.155.25428.135.155.2551,022
10428.135.156.0/2228.135.156.1 to 28.135.159.25428.135.159.2551,022
10528.135.160.0/2228.135.160.1 to 28.135.163.25428.135.163.2551,022
10628.135.164.0/2228.135.164.1 to 28.135.167.25428.135.167.2551,022
10728.135.168.0/2228.135.168.1 to 28.135.171.25428.135.171.2551,022
10828.135.172.0/2228.135.172.1 to 28.135.175.25428.135.175.2551,022
10928.135.176.0/2228.135.176.1 to 28.135.179.25428.135.179.2551,022
11028.135.180.0/2228.135.180.1 to 28.135.183.25428.135.183.2551,022
11128.135.184.0/2228.135.184.1 to 28.135.187.25428.135.187.2551,022
11228.135.188.0/2228.135.188.1 to 28.135.191.25428.135.191.2551,022
11328.135.192.0/2228.135.192.1 to 28.135.195.25428.135.195.2551,022
11428.135.196.0/2228.135.196.1 to 28.135.199.25428.135.199.2551,022
11528.135.200.0/2228.135.200.1 to 28.135.203.25428.135.203.2551,022
11628.135.204.0/2228.135.204.1 to 28.135.207.25428.135.207.2551,022
11728.135.208.0/2228.135.208.1 to 28.135.211.25428.135.211.2551,022
11828.135.212.0/2228.135.212.1 to 28.135.215.25428.135.215.2551,022
11928.135.216.0/2228.135.216.1 to 28.135.219.25428.135.219.2551,022
12028.135.220.0/2228.135.220.1 to 28.135.223.25428.135.223.2551,022
12128.135.224.0/2228.135.224.1 to 28.135.227.25428.135.227.2551,022
12228.135.228.0/2228.135.228.1 to 28.135.231.25428.135.231.2551,022
12328.135.232.0/2228.135.232.1 to 28.135.235.25428.135.235.2551,022
12428.135.236.0/2228.135.236.1 to 28.135.239.25428.135.239.2551,022
12528.135.240.0/2228.135.240.1 to 28.135.243.25428.135.243.2551,022
12628.135.244.0/2228.135.244.1 to 28.135.247.25428.135.247.2551,022
12728.135.248.0/2228.135.248.1 to 28.135.251.25428.135.251.2551,022
12828.135.252.0/2228.135.252.1 to 28.135.255.25428.135.255.2551,022

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.