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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.

Network54.0.0.0/7
Usable hosts33,554,430
Subnet mask254.0.0.0
Addresses33,554,432
Network address
54.0.0.0
Broadcast address
55.255.255.255
First usable
54.0.0.1
Last usable
55.255.255.254
Usable hosts
33,554,430 (33,554,432 less the network and broadcast addresses)
Subnet mask
254.0.0.0
Wildcard mask
1.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/7
Type
Public public
Old class
A (default /8)
As numbers
Hex 36000000 · Integer 905969664 to 939524095
Reverse DNS zones
54.in-addr.arpa
55.in-addr.arpa
/7 is not on a 8-bit boundary, so it takes 2 /8 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00110110.00000000.00000000.0000000054.0.0.0
Subnet mask11111110.00000000.00000000.00000000254.0.0.0
Network00110110.00000000.00000000.0000000054.0.0.0
Broadcast00110111.11111111.11111111.1111111155.255.255.255
Split into smaller subnets/13
/8 (2)/9 (4)/10 (8)/11 (16)/12 (32)/13 (64)/14 (128)/15 (256)/16 (512)/17 (1,024)/18 (2,048)/19 (4,096)

54.0.0.0/7 makes 64 subnets of /13.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
154.0.0.0/1354.0.0.1 to 54.7.255.25454.7.255.255524,286
254.8.0.0/1354.8.0.1 to 54.15.255.25454.15.255.255524,286
354.16.0.0/1354.16.0.1 to 54.23.255.25454.23.255.255524,286
454.24.0.0/1354.24.0.1 to 54.31.255.25454.31.255.255524,286
554.32.0.0/1354.32.0.1 to 54.39.255.25454.39.255.255524,286
654.40.0.0/1354.40.0.1 to 54.47.255.25454.47.255.255524,286
754.48.0.0/1354.48.0.1 to 54.55.255.25454.55.255.255524,286
854.56.0.0/1354.56.0.1 to 54.63.255.25454.63.255.255524,286
954.64.0.0/1354.64.0.1 to 54.71.255.25454.71.255.255524,286
1054.72.0.0/1354.72.0.1 to 54.79.255.25454.79.255.255524,286
1154.80.0.0/1354.80.0.1 to 54.87.255.25454.87.255.255524,286
1254.88.0.0/1354.88.0.1 to 54.95.255.25454.95.255.255524,286
1354.96.0.0/1354.96.0.1 to 54.103.255.25454.103.255.255524,286
1454.104.0.0/1354.104.0.1 to 54.111.255.25454.111.255.255524,286
1554.112.0.0/1354.112.0.1 to 54.119.255.25454.119.255.255524,286
1654.120.0.0/1354.120.0.1 to 54.127.255.25454.127.255.255524,286
1754.128.0.0/1354.128.0.1 to 54.135.255.25454.135.255.255524,286
1854.136.0.0/1354.136.0.1 to 54.143.255.25454.143.255.255524,286
1954.144.0.0/1354.144.0.1 to 54.151.255.25454.151.255.255524,286
2054.152.0.0/1354.152.0.1 to 54.159.255.25454.159.255.255524,286
2154.160.0.0/1354.160.0.1 to 54.167.255.25454.167.255.255524,286
2254.168.0.0/1354.168.0.1 to 54.175.255.25454.175.255.255524,286
2354.176.0.0/1354.176.0.1 to 54.183.255.25454.183.255.255524,286
2454.184.0.0/1354.184.0.1 to 54.191.255.25454.191.255.255524,286
2554.192.0.0/1354.192.0.1 to 54.199.255.25454.199.255.255524,286
2654.200.0.0/1354.200.0.1 to 54.207.255.25454.207.255.255524,286
2754.208.0.0/1354.208.0.1 to 54.215.255.25454.215.255.255524,286
2854.216.0.0/1354.216.0.1 to 54.223.255.25454.223.255.255524,286
2954.224.0.0/1354.224.0.1 to 54.231.255.25454.231.255.255524,286
3054.232.0.0/1354.232.0.1 to 54.239.255.25454.239.255.255524,286
3154.240.0.0/1354.240.0.1 to 54.247.255.25454.247.255.255524,286
3254.248.0.0/1354.248.0.1 to 54.255.255.25454.255.255.255524,286
3355.0.0.0/1355.0.0.1 to 55.7.255.25455.7.255.255524,286
3455.8.0.0/1355.8.0.1 to 55.15.255.25455.15.255.255524,286
3555.16.0.0/1355.16.0.1 to 55.23.255.25455.23.255.255524,286
3655.24.0.0/1355.24.0.1 to 55.31.255.25455.31.255.255524,286
3755.32.0.0/1355.32.0.1 to 55.39.255.25455.39.255.255524,286
3855.40.0.0/1355.40.0.1 to 55.47.255.25455.47.255.255524,286
3955.48.0.0/1355.48.0.1 to 55.55.255.25455.55.255.255524,286
4055.56.0.0/1355.56.0.1 to 55.63.255.25455.63.255.255524,286
4155.64.0.0/1355.64.0.1 to 55.71.255.25455.71.255.255524,286
4255.72.0.0/1355.72.0.1 to 55.79.255.25455.79.255.255524,286
4355.80.0.0/1355.80.0.1 to 55.87.255.25455.87.255.255524,286
4455.88.0.0/1355.88.0.1 to 55.95.255.25455.95.255.255524,286
4555.96.0.0/1355.96.0.1 to 55.103.255.25455.103.255.255524,286
4655.104.0.0/1355.104.0.1 to 55.111.255.25455.111.255.255524,286
4755.112.0.0/1355.112.0.1 to 55.119.255.25455.119.255.255524,286
4855.120.0.0/1355.120.0.1 to 55.127.255.25455.127.255.255524,286
4955.128.0.0/1355.128.0.1 to 55.135.255.25455.135.255.255524,286
5055.136.0.0/1355.136.0.1 to 55.143.255.25455.143.255.255524,286
5155.144.0.0/1355.144.0.1 to 55.151.255.25455.151.255.255524,286
5255.152.0.0/1355.152.0.1 to 55.159.255.25455.159.255.255524,286
5355.160.0.0/1355.160.0.1 to 55.167.255.25455.167.255.255524,286
5455.168.0.0/1355.168.0.1 to 55.175.255.25455.175.255.255524,286
5555.176.0.0/1355.176.0.1 to 55.183.255.25455.183.255.255524,286
5655.184.0.0/1355.184.0.1 to 55.191.255.25455.191.255.255524,286
5755.192.0.0/1355.192.0.1 to 55.199.255.25455.199.255.255524,286
5855.200.0.0/1355.200.0.1 to 55.207.255.25455.207.255.255524,286
5955.208.0.0/1355.208.0.1 to 55.215.255.25455.215.255.255524,286
6055.216.0.0/1355.216.0.1 to 55.223.255.25455.223.255.255524,286
6155.224.0.0/1355.224.0.1 to 55.231.255.25455.231.255.255524,286
6255.232.0.0/1355.232.0.1 to 55.239.255.25455.239.255.255524,286
6355.240.0.0/1355.240.0.1 to 55.247.255.25455.247.255.255524,286
6455.248.0.0/1355.248.0.1 to 55.255.255.25455.255.255.255524,286

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.