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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.

Network0.180.0.0/15
Usable hosts131,070
Subnet mask255.254.0.0
Addresses131,072
Network address
0.180.0.0
Broadcast address
0.181.255.255
First usable
0.180.0.1
Last usable
0.181.255.254
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
This network 0.0.0.0/8
Not routed; 0.0.0.0 means "any address" in settings
Old class
A (default /8)
As numbers
Hex 00B40000 · Integer 11796480 to 11927551
Reverse DNS zones
180.0.in-addr.arpa
181.0.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
Address00000000.10110100.00000000.000000000.180.0.0
Subnet mask11111111.11111110.00000000.00000000255.254.0.0
Network00000000.10110100.00000000.000000000.180.0.0
Broadcast00000000.10110101.11111111.111111110.181.255.255
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)

0.180.0.0/15 makes 128 subnets of /22.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
10.180.0.0/220.180.0.1 to 0.180.3.2540.180.3.2551,022
20.180.4.0/220.180.4.1 to 0.180.7.2540.180.7.2551,022
30.180.8.0/220.180.8.1 to 0.180.11.2540.180.11.2551,022
40.180.12.0/220.180.12.1 to 0.180.15.2540.180.15.2551,022
50.180.16.0/220.180.16.1 to 0.180.19.2540.180.19.2551,022
60.180.20.0/220.180.20.1 to 0.180.23.2540.180.23.2551,022
70.180.24.0/220.180.24.1 to 0.180.27.2540.180.27.2551,022
80.180.28.0/220.180.28.1 to 0.180.31.2540.180.31.2551,022
90.180.32.0/220.180.32.1 to 0.180.35.2540.180.35.2551,022
100.180.36.0/220.180.36.1 to 0.180.39.2540.180.39.2551,022
110.180.40.0/220.180.40.1 to 0.180.43.2540.180.43.2551,022
120.180.44.0/220.180.44.1 to 0.180.47.2540.180.47.2551,022
130.180.48.0/220.180.48.1 to 0.180.51.2540.180.51.2551,022
140.180.52.0/220.180.52.1 to 0.180.55.2540.180.55.2551,022
150.180.56.0/220.180.56.1 to 0.180.59.2540.180.59.2551,022
160.180.60.0/220.180.60.1 to 0.180.63.2540.180.63.2551,022
170.180.64.0/220.180.64.1 to 0.180.67.2540.180.67.2551,022
180.180.68.0/220.180.68.1 to 0.180.71.2540.180.71.2551,022
190.180.72.0/220.180.72.1 to 0.180.75.2540.180.75.2551,022
200.180.76.0/220.180.76.1 to 0.180.79.2540.180.79.2551,022
210.180.80.0/220.180.80.1 to 0.180.83.2540.180.83.2551,022
220.180.84.0/220.180.84.1 to 0.180.87.2540.180.87.2551,022
230.180.88.0/220.180.88.1 to 0.180.91.2540.180.91.2551,022
240.180.92.0/220.180.92.1 to 0.180.95.2540.180.95.2551,022
250.180.96.0/220.180.96.1 to 0.180.99.2540.180.99.2551,022
260.180.100.0/220.180.100.1 to 0.180.103.2540.180.103.2551,022
270.180.104.0/220.180.104.1 to 0.180.107.2540.180.107.2551,022
280.180.108.0/220.180.108.1 to 0.180.111.2540.180.111.2551,022
290.180.112.0/220.180.112.1 to 0.180.115.2540.180.115.2551,022
300.180.116.0/220.180.116.1 to 0.180.119.2540.180.119.2551,022
310.180.120.0/220.180.120.1 to 0.180.123.2540.180.123.2551,022
320.180.124.0/220.180.124.1 to 0.180.127.2540.180.127.2551,022
330.180.128.0/220.180.128.1 to 0.180.131.2540.180.131.2551,022
340.180.132.0/220.180.132.1 to 0.180.135.2540.180.135.2551,022
350.180.136.0/220.180.136.1 to 0.180.139.2540.180.139.2551,022
360.180.140.0/220.180.140.1 to 0.180.143.2540.180.143.2551,022
370.180.144.0/220.180.144.1 to 0.180.147.2540.180.147.2551,022
380.180.148.0/220.180.148.1 to 0.180.151.2540.180.151.2551,022
390.180.152.0/220.180.152.1 to 0.180.155.2540.180.155.2551,022
400.180.156.0/220.180.156.1 to 0.180.159.2540.180.159.2551,022
410.180.160.0/220.180.160.1 to 0.180.163.2540.180.163.2551,022
420.180.164.0/220.180.164.1 to 0.180.167.2540.180.167.2551,022
430.180.168.0/220.180.168.1 to 0.180.171.2540.180.171.2551,022
440.180.172.0/220.180.172.1 to 0.180.175.2540.180.175.2551,022
450.180.176.0/220.180.176.1 to 0.180.179.2540.180.179.2551,022
460.180.180.0/220.180.180.1 to 0.180.183.2540.180.183.2551,022
470.180.184.0/220.180.184.1 to 0.180.187.2540.180.187.2551,022
480.180.188.0/220.180.188.1 to 0.180.191.2540.180.191.2551,022
490.180.192.0/220.180.192.1 to 0.180.195.2540.180.195.2551,022
500.180.196.0/220.180.196.1 to 0.180.199.2540.180.199.2551,022
510.180.200.0/220.180.200.1 to 0.180.203.2540.180.203.2551,022
520.180.204.0/220.180.204.1 to 0.180.207.2540.180.207.2551,022
530.180.208.0/220.180.208.1 to 0.180.211.2540.180.211.2551,022
540.180.212.0/220.180.212.1 to 0.180.215.2540.180.215.2551,022
550.180.216.0/220.180.216.1 to 0.180.219.2540.180.219.2551,022
560.180.220.0/220.180.220.1 to 0.180.223.2540.180.223.2551,022
570.180.224.0/220.180.224.1 to 0.180.227.2540.180.227.2551,022
580.180.228.0/220.180.228.1 to 0.180.231.2540.180.231.2551,022
590.180.232.0/220.180.232.1 to 0.180.235.2540.180.235.2551,022
600.180.236.0/220.180.236.1 to 0.180.239.2540.180.239.2551,022
610.180.240.0/220.180.240.1 to 0.180.243.2540.180.243.2551,022
620.180.244.0/220.180.244.1 to 0.180.247.2540.180.247.2551,022
630.180.248.0/220.180.248.1 to 0.180.251.2540.180.251.2551,022
640.180.252.0/220.180.252.1 to 0.180.255.2540.180.255.2551,022
650.181.0.0/220.181.0.1 to 0.181.3.2540.181.3.2551,022
660.181.4.0/220.181.4.1 to 0.181.7.2540.181.7.2551,022
670.181.8.0/220.181.8.1 to 0.181.11.2540.181.11.2551,022
680.181.12.0/220.181.12.1 to 0.181.15.2540.181.15.2551,022
690.181.16.0/220.181.16.1 to 0.181.19.2540.181.19.2551,022
700.181.20.0/220.181.20.1 to 0.181.23.2540.181.23.2551,022
710.181.24.0/220.181.24.1 to 0.181.27.2540.181.27.2551,022
720.181.28.0/220.181.28.1 to 0.181.31.2540.181.31.2551,022
730.181.32.0/220.181.32.1 to 0.181.35.2540.181.35.2551,022
740.181.36.0/220.181.36.1 to 0.181.39.2540.181.39.2551,022
750.181.40.0/220.181.40.1 to 0.181.43.2540.181.43.2551,022
760.181.44.0/220.181.44.1 to 0.181.47.2540.181.47.2551,022
770.181.48.0/220.181.48.1 to 0.181.51.2540.181.51.2551,022
780.181.52.0/220.181.52.1 to 0.181.55.2540.181.55.2551,022
790.181.56.0/220.181.56.1 to 0.181.59.2540.181.59.2551,022
800.181.60.0/220.181.60.1 to 0.181.63.2540.181.63.2551,022
810.181.64.0/220.181.64.1 to 0.181.67.2540.181.67.2551,022
820.181.68.0/220.181.68.1 to 0.181.71.2540.181.71.2551,022
830.181.72.0/220.181.72.1 to 0.181.75.2540.181.75.2551,022
840.181.76.0/220.181.76.1 to 0.181.79.2540.181.79.2551,022
850.181.80.0/220.181.80.1 to 0.181.83.2540.181.83.2551,022
860.181.84.0/220.181.84.1 to 0.181.87.2540.181.87.2551,022
870.181.88.0/220.181.88.1 to 0.181.91.2540.181.91.2551,022
880.181.92.0/220.181.92.1 to 0.181.95.2540.181.95.2551,022
890.181.96.0/220.181.96.1 to 0.181.99.2540.181.99.2551,022
900.181.100.0/220.181.100.1 to 0.181.103.2540.181.103.2551,022
910.181.104.0/220.181.104.1 to 0.181.107.2540.181.107.2551,022
920.181.108.0/220.181.108.1 to 0.181.111.2540.181.111.2551,022
930.181.112.0/220.181.112.1 to 0.181.115.2540.181.115.2551,022
940.181.116.0/220.181.116.1 to 0.181.119.2540.181.119.2551,022
950.181.120.0/220.181.120.1 to 0.181.123.2540.181.123.2551,022
960.181.124.0/220.181.124.1 to 0.181.127.2540.181.127.2551,022
970.181.128.0/220.181.128.1 to 0.181.131.2540.181.131.2551,022
980.181.132.0/220.181.132.1 to 0.181.135.2540.181.135.2551,022
990.181.136.0/220.181.136.1 to 0.181.139.2540.181.139.2551,022
1000.181.140.0/220.181.140.1 to 0.181.143.2540.181.143.2551,022
1010.181.144.0/220.181.144.1 to 0.181.147.2540.181.147.2551,022
1020.181.148.0/220.181.148.1 to 0.181.151.2540.181.151.2551,022
1030.181.152.0/220.181.152.1 to 0.181.155.2540.181.155.2551,022
1040.181.156.0/220.181.156.1 to 0.181.159.2540.181.159.2551,022
1050.181.160.0/220.181.160.1 to 0.181.163.2540.181.163.2551,022
1060.181.164.0/220.181.164.1 to 0.181.167.2540.181.167.2551,022
1070.181.168.0/220.181.168.1 to 0.181.171.2540.181.171.2551,022
1080.181.172.0/220.181.172.1 to 0.181.175.2540.181.175.2551,022
1090.181.176.0/220.181.176.1 to 0.181.179.2540.181.179.2551,022
1100.181.180.0/220.181.180.1 to 0.181.183.2540.181.183.2551,022
1110.181.184.0/220.181.184.1 to 0.181.187.2540.181.187.2551,022
1120.181.188.0/220.181.188.1 to 0.181.191.2540.181.191.2551,022
1130.181.192.0/220.181.192.1 to 0.181.195.2540.181.195.2551,022
1140.181.196.0/220.181.196.1 to 0.181.199.2540.181.199.2551,022
1150.181.200.0/220.181.200.1 to 0.181.203.2540.181.203.2551,022
1160.181.204.0/220.181.204.1 to 0.181.207.2540.181.207.2551,022
1170.181.208.0/220.181.208.1 to 0.181.211.2540.181.211.2551,022
1180.181.212.0/220.181.212.1 to 0.181.215.2540.181.215.2551,022
1190.181.216.0/220.181.216.1 to 0.181.219.2540.181.219.2551,022
1200.181.220.0/220.181.220.1 to 0.181.223.2540.181.223.2551,022
1210.181.224.0/220.181.224.1 to 0.181.227.2540.181.227.2551,022
1220.181.228.0/220.181.228.1 to 0.181.231.2540.181.231.2551,022
1230.181.232.0/220.181.232.1 to 0.181.235.2540.181.235.2551,022
1240.181.236.0/220.181.236.1 to 0.181.239.2540.181.239.2551,022
1250.181.240.0/220.181.240.1 to 0.181.243.2540.181.243.2551,022
1260.181.244.0/220.181.244.1 to 0.181.247.2540.181.247.2551,022
1270.181.248.0/220.181.248.1 to 0.181.251.2540.181.251.2551,022
1280.181.252.0/220.181.252.1 to 0.181.255.2540.181.255.2551,022

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.