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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.

Network15.44.0.0/15
Usable hosts131,070
Subnet mask255.254.0.0
Addresses131,072
Network address
15.44.0.0
Broadcast address
15.45.255.255
First usable
15.44.0.1
Last usable
15.45.255.254
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 0F2C0000 · Integer 254541824 to 254672895
Reverse DNS zones
44.15.in-addr.arpa
45.15.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
Address00001111.00101100.00000000.0000000015.44.0.0
Subnet mask11111111.11111110.00000000.00000000255.254.0.0
Network00001111.00101100.00000000.0000000015.44.0.0
Broadcast00001111.00101101.11111111.1111111115.45.255.255
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)

15.44.0.0/15 makes 128 subnets of /22.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
115.44.0.0/2215.44.0.1 to 15.44.3.25415.44.3.2551,022
215.44.4.0/2215.44.4.1 to 15.44.7.25415.44.7.2551,022
315.44.8.0/2215.44.8.1 to 15.44.11.25415.44.11.2551,022
415.44.12.0/2215.44.12.1 to 15.44.15.25415.44.15.2551,022
515.44.16.0/2215.44.16.1 to 15.44.19.25415.44.19.2551,022
615.44.20.0/2215.44.20.1 to 15.44.23.25415.44.23.2551,022
715.44.24.0/2215.44.24.1 to 15.44.27.25415.44.27.2551,022
815.44.28.0/2215.44.28.1 to 15.44.31.25415.44.31.2551,022
915.44.32.0/2215.44.32.1 to 15.44.35.25415.44.35.2551,022
1015.44.36.0/2215.44.36.1 to 15.44.39.25415.44.39.2551,022
1115.44.40.0/2215.44.40.1 to 15.44.43.25415.44.43.2551,022
1215.44.44.0/2215.44.44.1 to 15.44.47.25415.44.47.2551,022
1315.44.48.0/2215.44.48.1 to 15.44.51.25415.44.51.2551,022
1415.44.52.0/2215.44.52.1 to 15.44.55.25415.44.55.2551,022
1515.44.56.0/2215.44.56.1 to 15.44.59.25415.44.59.2551,022
1615.44.60.0/2215.44.60.1 to 15.44.63.25415.44.63.2551,022
1715.44.64.0/2215.44.64.1 to 15.44.67.25415.44.67.2551,022
1815.44.68.0/2215.44.68.1 to 15.44.71.25415.44.71.2551,022
1915.44.72.0/2215.44.72.1 to 15.44.75.25415.44.75.2551,022
2015.44.76.0/2215.44.76.1 to 15.44.79.25415.44.79.2551,022
2115.44.80.0/2215.44.80.1 to 15.44.83.25415.44.83.2551,022
2215.44.84.0/2215.44.84.1 to 15.44.87.25415.44.87.2551,022
2315.44.88.0/2215.44.88.1 to 15.44.91.25415.44.91.2551,022
2415.44.92.0/2215.44.92.1 to 15.44.95.25415.44.95.2551,022
2515.44.96.0/2215.44.96.1 to 15.44.99.25415.44.99.2551,022
2615.44.100.0/2215.44.100.1 to 15.44.103.25415.44.103.2551,022
2715.44.104.0/2215.44.104.1 to 15.44.107.25415.44.107.2551,022
2815.44.108.0/2215.44.108.1 to 15.44.111.25415.44.111.2551,022
2915.44.112.0/2215.44.112.1 to 15.44.115.25415.44.115.2551,022
3015.44.116.0/2215.44.116.1 to 15.44.119.25415.44.119.2551,022
3115.44.120.0/2215.44.120.1 to 15.44.123.25415.44.123.2551,022
3215.44.124.0/2215.44.124.1 to 15.44.127.25415.44.127.2551,022
3315.44.128.0/2215.44.128.1 to 15.44.131.25415.44.131.2551,022
3415.44.132.0/2215.44.132.1 to 15.44.135.25415.44.135.2551,022
3515.44.136.0/2215.44.136.1 to 15.44.139.25415.44.139.2551,022
3615.44.140.0/2215.44.140.1 to 15.44.143.25415.44.143.2551,022
3715.44.144.0/2215.44.144.1 to 15.44.147.25415.44.147.2551,022
3815.44.148.0/2215.44.148.1 to 15.44.151.25415.44.151.2551,022
3915.44.152.0/2215.44.152.1 to 15.44.155.25415.44.155.2551,022
4015.44.156.0/2215.44.156.1 to 15.44.159.25415.44.159.2551,022
4115.44.160.0/2215.44.160.1 to 15.44.163.25415.44.163.2551,022
4215.44.164.0/2215.44.164.1 to 15.44.167.25415.44.167.2551,022
4315.44.168.0/2215.44.168.1 to 15.44.171.25415.44.171.2551,022
4415.44.172.0/2215.44.172.1 to 15.44.175.25415.44.175.2551,022
4515.44.176.0/2215.44.176.1 to 15.44.179.25415.44.179.2551,022
4615.44.180.0/2215.44.180.1 to 15.44.183.25415.44.183.2551,022
4715.44.184.0/2215.44.184.1 to 15.44.187.25415.44.187.2551,022
4815.44.188.0/2215.44.188.1 to 15.44.191.25415.44.191.2551,022
4915.44.192.0/2215.44.192.1 to 15.44.195.25415.44.195.2551,022
5015.44.196.0/2215.44.196.1 to 15.44.199.25415.44.199.2551,022
5115.44.200.0/2215.44.200.1 to 15.44.203.25415.44.203.2551,022
5215.44.204.0/2215.44.204.1 to 15.44.207.25415.44.207.2551,022
5315.44.208.0/2215.44.208.1 to 15.44.211.25415.44.211.2551,022
5415.44.212.0/2215.44.212.1 to 15.44.215.25415.44.215.2551,022
5515.44.216.0/2215.44.216.1 to 15.44.219.25415.44.219.2551,022
5615.44.220.0/2215.44.220.1 to 15.44.223.25415.44.223.2551,022
5715.44.224.0/2215.44.224.1 to 15.44.227.25415.44.227.2551,022
5815.44.228.0/2215.44.228.1 to 15.44.231.25415.44.231.2551,022
5915.44.232.0/2215.44.232.1 to 15.44.235.25415.44.235.2551,022
6015.44.236.0/2215.44.236.1 to 15.44.239.25415.44.239.2551,022
6115.44.240.0/2215.44.240.1 to 15.44.243.25415.44.243.2551,022
6215.44.244.0/2215.44.244.1 to 15.44.247.25415.44.247.2551,022
6315.44.248.0/2215.44.248.1 to 15.44.251.25415.44.251.2551,022
6415.44.252.0/2215.44.252.1 to 15.44.255.25415.44.255.2551,022
6515.45.0.0/2215.45.0.1 to 15.45.3.25415.45.3.2551,022
6615.45.4.0/2215.45.4.1 to 15.45.7.25415.45.7.2551,022
6715.45.8.0/2215.45.8.1 to 15.45.11.25415.45.11.2551,022
6815.45.12.0/2215.45.12.1 to 15.45.15.25415.45.15.2551,022
6915.45.16.0/2215.45.16.1 to 15.45.19.25415.45.19.2551,022
7015.45.20.0/2215.45.20.1 to 15.45.23.25415.45.23.2551,022
7115.45.24.0/2215.45.24.1 to 15.45.27.25415.45.27.2551,022
7215.45.28.0/2215.45.28.1 to 15.45.31.25415.45.31.2551,022
7315.45.32.0/2215.45.32.1 to 15.45.35.25415.45.35.2551,022
7415.45.36.0/2215.45.36.1 to 15.45.39.25415.45.39.2551,022
7515.45.40.0/2215.45.40.1 to 15.45.43.25415.45.43.2551,022
7615.45.44.0/2215.45.44.1 to 15.45.47.25415.45.47.2551,022
7715.45.48.0/2215.45.48.1 to 15.45.51.25415.45.51.2551,022
7815.45.52.0/2215.45.52.1 to 15.45.55.25415.45.55.2551,022
7915.45.56.0/2215.45.56.1 to 15.45.59.25415.45.59.2551,022
8015.45.60.0/2215.45.60.1 to 15.45.63.25415.45.63.2551,022
8115.45.64.0/2215.45.64.1 to 15.45.67.25415.45.67.2551,022
8215.45.68.0/2215.45.68.1 to 15.45.71.25415.45.71.2551,022
8315.45.72.0/2215.45.72.1 to 15.45.75.25415.45.75.2551,022
8415.45.76.0/2215.45.76.1 to 15.45.79.25415.45.79.2551,022
8515.45.80.0/2215.45.80.1 to 15.45.83.25415.45.83.2551,022
8615.45.84.0/2215.45.84.1 to 15.45.87.25415.45.87.2551,022
8715.45.88.0/2215.45.88.1 to 15.45.91.25415.45.91.2551,022
8815.45.92.0/2215.45.92.1 to 15.45.95.25415.45.95.2551,022
8915.45.96.0/2215.45.96.1 to 15.45.99.25415.45.99.2551,022
9015.45.100.0/2215.45.100.1 to 15.45.103.25415.45.103.2551,022
9115.45.104.0/2215.45.104.1 to 15.45.107.25415.45.107.2551,022
9215.45.108.0/2215.45.108.1 to 15.45.111.25415.45.111.2551,022
9315.45.112.0/2215.45.112.1 to 15.45.115.25415.45.115.2551,022
9415.45.116.0/2215.45.116.1 to 15.45.119.25415.45.119.2551,022
9515.45.120.0/2215.45.120.1 to 15.45.123.25415.45.123.2551,022
9615.45.124.0/2215.45.124.1 to 15.45.127.25415.45.127.2551,022
9715.45.128.0/2215.45.128.1 to 15.45.131.25415.45.131.2551,022
9815.45.132.0/2215.45.132.1 to 15.45.135.25415.45.135.2551,022
9915.45.136.0/2215.45.136.1 to 15.45.139.25415.45.139.2551,022
10015.45.140.0/2215.45.140.1 to 15.45.143.25415.45.143.2551,022
10115.45.144.0/2215.45.144.1 to 15.45.147.25415.45.147.2551,022
10215.45.148.0/2215.45.148.1 to 15.45.151.25415.45.151.2551,022
10315.45.152.0/2215.45.152.1 to 15.45.155.25415.45.155.2551,022
10415.45.156.0/2215.45.156.1 to 15.45.159.25415.45.159.2551,022
10515.45.160.0/2215.45.160.1 to 15.45.163.25415.45.163.2551,022
10615.45.164.0/2215.45.164.1 to 15.45.167.25415.45.167.2551,022
10715.45.168.0/2215.45.168.1 to 15.45.171.25415.45.171.2551,022
10815.45.172.0/2215.45.172.1 to 15.45.175.25415.45.175.2551,022
10915.45.176.0/2215.45.176.1 to 15.45.179.25415.45.179.2551,022
11015.45.180.0/2215.45.180.1 to 15.45.183.25415.45.183.2551,022
11115.45.184.0/2215.45.184.1 to 15.45.187.25415.45.187.2551,022
11215.45.188.0/2215.45.188.1 to 15.45.191.25415.45.191.2551,022
11315.45.192.0/2215.45.192.1 to 15.45.195.25415.45.195.2551,022
11415.45.196.0/2215.45.196.1 to 15.45.199.25415.45.199.2551,022
11515.45.200.0/2215.45.200.1 to 15.45.203.25415.45.203.2551,022
11615.45.204.0/2215.45.204.1 to 15.45.207.25415.45.207.2551,022
11715.45.208.0/2215.45.208.1 to 15.45.211.25415.45.211.2551,022
11815.45.212.0/2215.45.212.1 to 15.45.215.25415.45.215.2551,022
11915.45.216.0/2215.45.216.1 to 15.45.219.25415.45.219.2551,022
12015.45.220.0/2215.45.220.1 to 15.45.223.25415.45.223.2551,022
12115.45.224.0/2215.45.224.1 to 15.45.227.25415.45.227.2551,022
12215.45.228.0/2215.45.228.1 to 15.45.231.25415.45.231.2551,022
12315.45.232.0/2215.45.232.1 to 15.45.235.25415.45.235.2551,022
12415.45.236.0/2215.45.236.1 to 15.45.239.25415.45.239.2551,022
12515.45.240.0/2215.45.240.1 to 15.45.243.25415.45.243.2551,022
12615.45.244.0/2215.45.244.1 to 15.45.247.25415.45.247.2551,022
12715.45.248.0/2215.45.248.1 to 15.45.251.25415.45.251.2551,022
12815.45.252.0/2215.45.252.1 to 15.45.255.25415.45.255.2551,022

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.