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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.

Network144.0.0.0/7
Usable hosts33,554,430
Subnet mask254.0.0.0
Addresses33,554,432
Network address
144.0.0.0
Broadcast address
145.255.255.255
First usable
144.0.0.1
Last usable
145.255.255.254
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
B (default /16)
As numbers
Hex 90000000 · Integer 2415919104 to 2449473535
Reverse DNS zones
144.in-addr.arpa
145.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
Address10010000.00000000.00000000.00000000144.0.0.0
Subnet mask11111110.00000000.00000000.00000000254.0.0.0
Network10010000.00000000.00000000.00000000144.0.0.0
Broadcast10010001.11111111.11111111.11111111145.255.255.255
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)

144.0.0.0/7 makes 64 subnets of /13.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1144.0.0.0/13144.0.0.1 to 144.7.255.254144.7.255.255524,286
2144.8.0.0/13144.8.0.1 to 144.15.255.254144.15.255.255524,286
3144.16.0.0/13144.16.0.1 to 144.23.255.254144.23.255.255524,286
4144.24.0.0/13144.24.0.1 to 144.31.255.254144.31.255.255524,286
5144.32.0.0/13144.32.0.1 to 144.39.255.254144.39.255.255524,286
6144.40.0.0/13144.40.0.1 to 144.47.255.254144.47.255.255524,286
7144.48.0.0/13144.48.0.1 to 144.55.255.254144.55.255.255524,286
8144.56.0.0/13144.56.0.1 to 144.63.255.254144.63.255.255524,286
9144.64.0.0/13144.64.0.1 to 144.71.255.254144.71.255.255524,286
10144.72.0.0/13144.72.0.1 to 144.79.255.254144.79.255.255524,286
11144.80.0.0/13144.80.0.1 to 144.87.255.254144.87.255.255524,286
12144.88.0.0/13144.88.0.1 to 144.95.255.254144.95.255.255524,286
13144.96.0.0/13144.96.0.1 to 144.103.255.254144.103.255.255524,286
14144.104.0.0/13144.104.0.1 to 144.111.255.254144.111.255.255524,286
15144.112.0.0/13144.112.0.1 to 144.119.255.254144.119.255.255524,286
16144.120.0.0/13144.120.0.1 to 144.127.255.254144.127.255.255524,286
17144.128.0.0/13144.128.0.1 to 144.135.255.254144.135.255.255524,286
18144.136.0.0/13144.136.0.1 to 144.143.255.254144.143.255.255524,286
19144.144.0.0/13144.144.0.1 to 144.151.255.254144.151.255.255524,286
20144.152.0.0/13144.152.0.1 to 144.159.255.254144.159.255.255524,286
21144.160.0.0/13144.160.0.1 to 144.167.255.254144.167.255.255524,286
22144.168.0.0/13144.168.0.1 to 144.175.255.254144.175.255.255524,286
23144.176.0.0/13144.176.0.1 to 144.183.255.254144.183.255.255524,286
24144.184.0.0/13144.184.0.1 to 144.191.255.254144.191.255.255524,286
25144.192.0.0/13144.192.0.1 to 144.199.255.254144.199.255.255524,286
26144.200.0.0/13144.200.0.1 to 144.207.255.254144.207.255.255524,286
27144.208.0.0/13144.208.0.1 to 144.215.255.254144.215.255.255524,286
28144.216.0.0/13144.216.0.1 to 144.223.255.254144.223.255.255524,286
29144.224.0.0/13144.224.0.1 to 144.231.255.254144.231.255.255524,286
30144.232.0.0/13144.232.0.1 to 144.239.255.254144.239.255.255524,286
31144.240.0.0/13144.240.0.1 to 144.247.255.254144.247.255.255524,286
32144.248.0.0/13144.248.0.1 to 144.255.255.254144.255.255.255524,286
33145.0.0.0/13145.0.0.1 to 145.7.255.254145.7.255.255524,286
34145.8.0.0/13145.8.0.1 to 145.15.255.254145.15.255.255524,286
35145.16.0.0/13145.16.0.1 to 145.23.255.254145.23.255.255524,286
36145.24.0.0/13145.24.0.1 to 145.31.255.254145.31.255.255524,286
37145.32.0.0/13145.32.0.1 to 145.39.255.254145.39.255.255524,286
38145.40.0.0/13145.40.0.1 to 145.47.255.254145.47.255.255524,286
39145.48.0.0/13145.48.0.1 to 145.55.255.254145.55.255.255524,286
40145.56.0.0/13145.56.0.1 to 145.63.255.254145.63.255.255524,286
41145.64.0.0/13145.64.0.1 to 145.71.255.254145.71.255.255524,286
42145.72.0.0/13145.72.0.1 to 145.79.255.254145.79.255.255524,286
43145.80.0.0/13145.80.0.1 to 145.87.255.254145.87.255.255524,286
44145.88.0.0/13145.88.0.1 to 145.95.255.254145.95.255.255524,286
45145.96.0.0/13145.96.0.1 to 145.103.255.254145.103.255.255524,286
46145.104.0.0/13145.104.0.1 to 145.111.255.254145.111.255.255524,286
47145.112.0.0/13145.112.0.1 to 145.119.255.254145.119.255.255524,286
48145.120.0.0/13145.120.0.1 to 145.127.255.254145.127.255.255524,286
49145.128.0.0/13145.128.0.1 to 145.135.255.254145.135.255.255524,286
50145.136.0.0/13145.136.0.1 to 145.143.255.254145.143.255.255524,286
51145.144.0.0/13145.144.0.1 to 145.151.255.254145.151.255.255524,286
52145.152.0.0/13145.152.0.1 to 145.159.255.254145.159.255.255524,286
53145.160.0.0/13145.160.0.1 to 145.167.255.254145.167.255.255524,286
54145.168.0.0/13145.168.0.1 to 145.175.255.254145.175.255.255524,286
55145.176.0.0/13145.176.0.1 to 145.183.255.254145.183.255.255524,286
56145.184.0.0/13145.184.0.1 to 145.191.255.254145.191.255.255524,286
57145.192.0.0/13145.192.0.1 to 145.199.255.254145.199.255.255524,286
58145.200.0.0/13145.200.0.1 to 145.207.255.254145.207.255.255524,286
59145.208.0.0/13145.208.0.1 to 145.215.255.254145.215.255.255524,286
60145.216.0.0/13145.216.0.1 to 145.223.255.254145.223.255.255524,286
61145.224.0.0/13145.224.0.1 to 145.231.255.254145.231.255.255524,286
62145.232.0.0/13145.232.0.1 to 145.239.255.254145.239.255.255524,286
63145.240.0.0/13145.240.0.1 to 145.247.255.254145.247.255.255524,286
64145.248.0.0/13145.248.0.1 to 145.255.255.254145.255.255.255524,286

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.