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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.

Network1.80.0.0/15
Usable hosts131,070
Subnet mask255.254.0.0
Addresses131,072
Network address
1.80.0.0
Broadcast address
1.81.255.255
First usable
1.80.0.1
Last usable
1.81.255.254
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 01500000 · Integer 22020096 to 22151167
Reverse DNS zones
80.1.in-addr.arpa
81.1.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
Address00000001.01010000.00000000.000000001.80.0.0
Subnet mask11111111.11111110.00000000.00000000255.254.0.0
Network00000001.01010000.00000000.000000001.80.0.0
Broadcast00000001.01010001.11111111.111111111.81.255.255
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)

1.80.0.0/15 makes 128 subnets of /22.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
11.80.0.0/221.80.0.1 to 1.80.3.2541.80.3.2551,022
21.80.4.0/221.80.4.1 to 1.80.7.2541.80.7.2551,022
31.80.8.0/221.80.8.1 to 1.80.11.2541.80.11.2551,022
41.80.12.0/221.80.12.1 to 1.80.15.2541.80.15.2551,022
51.80.16.0/221.80.16.1 to 1.80.19.2541.80.19.2551,022
61.80.20.0/221.80.20.1 to 1.80.23.2541.80.23.2551,022
71.80.24.0/221.80.24.1 to 1.80.27.2541.80.27.2551,022
81.80.28.0/221.80.28.1 to 1.80.31.2541.80.31.2551,022
91.80.32.0/221.80.32.1 to 1.80.35.2541.80.35.2551,022
101.80.36.0/221.80.36.1 to 1.80.39.2541.80.39.2551,022
111.80.40.0/221.80.40.1 to 1.80.43.2541.80.43.2551,022
121.80.44.0/221.80.44.1 to 1.80.47.2541.80.47.2551,022
131.80.48.0/221.80.48.1 to 1.80.51.2541.80.51.2551,022
141.80.52.0/221.80.52.1 to 1.80.55.2541.80.55.2551,022
151.80.56.0/221.80.56.1 to 1.80.59.2541.80.59.2551,022
161.80.60.0/221.80.60.1 to 1.80.63.2541.80.63.2551,022
171.80.64.0/221.80.64.1 to 1.80.67.2541.80.67.2551,022
181.80.68.0/221.80.68.1 to 1.80.71.2541.80.71.2551,022
191.80.72.0/221.80.72.1 to 1.80.75.2541.80.75.2551,022
201.80.76.0/221.80.76.1 to 1.80.79.2541.80.79.2551,022
211.80.80.0/221.80.80.1 to 1.80.83.2541.80.83.2551,022
221.80.84.0/221.80.84.1 to 1.80.87.2541.80.87.2551,022
231.80.88.0/221.80.88.1 to 1.80.91.2541.80.91.2551,022
241.80.92.0/221.80.92.1 to 1.80.95.2541.80.95.2551,022
251.80.96.0/221.80.96.1 to 1.80.99.2541.80.99.2551,022
261.80.100.0/221.80.100.1 to 1.80.103.2541.80.103.2551,022
271.80.104.0/221.80.104.1 to 1.80.107.2541.80.107.2551,022
281.80.108.0/221.80.108.1 to 1.80.111.2541.80.111.2551,022
291.80.112.0/221.80.112.1 to 1.80.115.2541.80.115.2551,022
301.80.116.0/221.80.116.1 to 1.80.119.2541.80.119.2551,022
311.80.120.0/221.80.120.1 to 1.80.123.2541.80.123.2551,022
321.80.124.0/221.80.124.1 to 1.80.127.2541.80.127.2551,022
331.80.128.0/221.80.128.1 to 1.80.131.2541.80.131.2551,022
341.80.132.0/221.80.132.1 to 1.80.135.2541.80.135.2551,022
351.80.136.0/221.80.136.1 to 1.80.139.2541.80.139.2551,022
361.80.140.0/221.80.140.1 to 1.80.143.2541.80.143.2551,022
371.80.144.0/221.80.144.1 to 1.80.147.2541.80.147.2551,022
381.80.148.0/221.80.148.1 to 1.80.151.2541.80.151.2551,022
391.80.152.0/221.80.152.1 to 1.80.155.2541.80.155.2551,022
401.80.156.0/221.80.156.1 to 1.80.159.2541.80.159.2551,022
411.80.160.0/221.80.160.1 to 1.80.163.2541.80.163.2551,022
421.80.164.0/221.80.164.1 to 1.80.167.2541.80.167.2551,022
431.80.168.0/221.80.168.1 to 1.80.171.2541.80.171.2551,022
441.80.172.0/221.80.172.1 to 1.80.175.2541.80.175.2551,022
451.80.176.0/221.80.176.1 to 1.80.179.2541.80.179.2551,022
461.80.180.0/221.80.180.1 to 1.80.183.2541.80.183.2551,022
471.80.184.0/221.80.184.1 to 1.80.187.2541.80.187.2551,022
481.80.188.0/221.80.188.1 to 1.80.191.2541.80.191.2551,022
491.80.192.0/221.80.192.1 to 1.80.195.2541.80.195.2551,022
501.80.196.0/221.80.196.1 to 1.80.199.2541.80.199.2551,022
511.80.200.0/221.80.200.1 to 1.80.203.2541.80.203.2551,022
521.80.204.0/221.80.204.1 to 1.80.207.2541.80.207.2551,022
531.80.208.0/221.80.208.1 to 1.80.211.2541.80.211.2551,022
541.80.212.0/221.80.212.1 to 1.80.215.2541.80.215.2551,022
551.80.216.0/221.80.216.1 to 1.80.219.2541.80.219.2551,022
561.80.220.0/221.80.220.1 to 1.80.223.2541.80.223.2551,022
571.80.224.0/221.80.224.1 to 1.80.227.2541.80.227.2551,022
581.80.228.0/221.80.228.1 to 1.80.231.2541.80.231.2551,022
591.80.232.0/221.80.232.1 to 1.80.235.2541.80.235.2551,022
601.80.236.0/221.80.236.1 to 1.80.239.2541.80.239.2551,022
611.80.240.0/221.80.240.1 to 1.80.243.2541.80.243.2551,022
621.80.244.0/221.80.244.1 to 1.80.247.2541.80.247.2551,022
631.80.248.0/221.80.248.1 to 1.80.251.2541.80.251.2551,022
641.80.252.0/221.80.252.1 to 1.80.255.2541.80.255.2551,022
651.81.0.0/221.81.0.1 to 1.81.3.2541.81.3.2551,022
661.81.4.0/221.81.4.1 to 1.81.7.2541.81.7.2551,022
671.81.8.0/221.81.8.1 to 1.81.11.2541.81.11.2551,022
681.81.12.0/221.81.12.1 to 1.81.15.2541.81.15.2551,022
691.81.16.0/221.81.16.1 to 1.81.19.2541.81.19.2551,022
701.81.20.0/221.81.20.1 to 1.81.23.2541.81.23.2551,022
711.81.24.0/221.81.24.1 to 1.81.27.2541.81.27.2551,022
721.81.28.0/221.81.28.1 to 1.81.31.2541.81.31.2551,022
731.81.32.0/221.81.32.1 to 1.81.35.2541.81.35.2551,022
741.81.36.0/221.81.36.1 to 1.81.39.2541.81.39.2551,022
751.81.40.0/221.81.40.1 to 1.81.43.2541.81.43.2551,022
761.81.44.0/221.81.44.1 to 1.81.47.2541.81.47.2551,022
771.81.48.0/221.81.48.1 to 1.81.51.2541.81.51.2551,022
781.81.52.0/221.81.52.1 to 1.81.55.2541.81.55.2551,022
791.81.56.0/221.81.56.1 to 1.81.59.2541.81.59.2551,022
801.81.60.0/221.81.60.1 to 1.81.63.2541.81.63.2551,022
811.81.64.0/221.81.64.1 to 1.81.67.2541.81.67.2551,022
821.81.68.0/221.81.68.1 to 1.81.71.2541.81.71.2551,022
831.81.72.0/221.81.72.1 to 1.81.75.2541.81.75.2551,022
841.81.76.0/221.81.76.1 to 1.81.79.2541.81.79.2551,022
851.81.80.0/221.81.80.1 to 1.81.83.2541.81.83.2551,022
861.81.84.0/221.81.84.1 to 1.81.87.2541.81.87.2551,022
871.81.88.0/221.81.88.1 to 1.81.91.2541.81.91.2551,022
881.81.92.0/221.81.92.1 to 1.81.95.2541.81.95.2551,022
891.81.96.0/221.81.96.1 to 1.81.99.2541.81.99.2551,022
901.81.100.0/221.81.100.1 to 1.81.103.2541.81.103.2551,022
911.81.104.0/221.81.104.1 to 1.81.107.2541.81.107.2551,022
921.81.108.0/221.81.108.1 to 1.81.111.2541.81.111.2551,022
931.81.112.0/221.81.112.1 to 1.81.115.2541.81.115.2551,022
941.81.116.0/221.81.116.1 to 1.81.119.2541.81.119.2551,022
951.81.120.0/221.81.120.1 to 1.81.123.2541.81.123.2551,022
961.81.124.0/221.81.124.1 to 1.81.127.2541.81.127.2551,022
971.81.128.0/221.81.128.1 to 1.81.131.2541.81.131.2551,022
981.81.132.0/221.81.132.1 to 1.81.135.2541.81.135.2551,022
991.81.136.0/221.81.136.1 to 1.81.139.2541.81.139.2551,022
1001.81.140.0/221.81.140.1 to 1.81.143.2541.81.143.2551,022
1011.81.144.0/221.81.144.1 to 1.81.147.2541.81.147.2551,022
1021.81.148.0/221.81.148.1 to 1.81.151.2541.81.151.2551,022
1031.81.152.0/221.81.152.1 to 1.81.155.2541.81.155.2551,022
1041.81.156.0/221.81.156.1 to 1.81.159.2541.81.159.2551,022
1051.81.160.0/221.81.160.1 to 1.81.163.2541.81.163.2551,022
1061.81.164.0/221.81.164.1 to 1.81.167.2541.81.167.2551,022
1071.81.168.0/221.81.168.1 to 1.81.171.2541.81.171.2551,022
1081.81.172.0/221.81.172.1 to 1.81.175.2541.81.175.2551,022
1091.81.176.0/221.81.176.1 to 1.81.179.2541.81.179.2551,022
1101.81.180.0/221.81.180.1 to 1.81.183.2541.81.183.2551,022
1111.81.184.0/221.81.184.1 to 1.81.187.2541.81.187.2551,022
1121.81.188.0/221.81.188.1 to 1.81.191.2541.81.191.2551,022
1131.81.192.0/221.81.192.1 to 1.81.195.2541.81.195.2551,022
1141.81.196.0/221.81.196.1 to 1.81.199.2541.81.199.2551,022
1151.81.200.0/221.81.200.1 to 1.81.203.2541.81.203.2551,022
1161.81.204.0/221.81.204.1 to 1.81.207.2541.81.207.2551,022
1171.81.208.0/221.81.208.1 to 1.81.211.2541.81.211.2551,022
1181.81.212.0/221.81.212.1 to 1.81.215.2541.81.215.2551,022
1191.81.216.0/221.81.216.1 to 1.81.219.2541.81.219.2551,022
1201.81.220.0/221.81.220.1 to 1.81.223.2541.81.223.2551,022
1211.81.224.0/221.81.224.1 to 1.81.227.2541.81.227.2551,022
1221.81.228.0/221.81.228.1 to 1.81.231.2541.81.231.2551,022
1231.81.232.0/221.81.232.1 to 1.81.235.2541.81.235.2551,022
1241.81.236.0/221.81.236.1 to 1.81.239.2541.81.239.2551,022
1251.81.240.0/221.81.240.1 to 1.81.243.2541.81.243.2551,022
1261.81.244.0/221.81.244.1 to 1.81.247.2541.81.247.2551,022
1271.81.248.0/221.81.248.1 to 1.81.251.2541.81.251.2551,022
1281.81.252.0/221.81.252.1 to 1.81.255.2541.81.255.2551,022

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.