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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.

Network242.136.0.0/14
Usable hosts262,142
Subnet mask255.252.0.0
Addresses262,144
Network address
242.136.0.0
Broadcast address
242.139.255.255
First usable
242.136.0.1
Last usable
242.139.255.254
Usable hosts
262,142 (262,144 less the network and broadcast addresses)
Subnet mask
255.252.0.0
Wildcard mask
0.3.255.255 (Cisco ACLs, OSPF)
Prefix length
/14
Type
Reserved 240.0.0.0/4
Future use; not usable on most systems
Old class
E (reserved)
As numbers
Hex F2880000 · Integer 4068999168 to 4069261311
Reverse DNS zones
136.242.in-addr.arpa
137.242.in-addr.arpa
138.242.in-addr.arpa
139.242.in-addr.arpa
/14 is not on a 8-bit boundary, so it takes 4 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11110010.10001000.00000000.00000000242.136.0.0
Subnet mask11111111.11111100.00000000.00000000255.252.0.0
Network11110010.10001000.00000000.00000000242.136.0.0
Broadcast11110010.10001011.11111111.11111111242.139.255.255
Split into smaller subnets/20
/15 (2)/16 (4)/17 (8)/18 (16)/19 (32)/20 (64)/21 (128)/22 (256)/23 (512)/24 (1,024)/25 (2,048)/26 (4,096)

242.136.0.0/14 makes 64 subnets of /20.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1242.136.0.0/20242.136.0.1 to 242.136.15.254242.136.15.2554,094
2242.136.16.0/20242.136.16.1 to 242.136.31.254242.136.31.2554,094
3242.136.32.0/20242.136.32.1 to 242.136.47.254242.136.47.2554,094
4242.136.48.0/20242.136.48.1 to 242.136.63.254242.136.63.2554,094
5242.136.64.0/20242.136.64.1 to 242.136.79.254242.136.79.2554,094
6242.136.80.0/20242.136.80.1 to 242.136.95.254242.136.95.2554,094
7242.136.96.0/20242.136.96.1 to 242.136.111.254242.136.111.2554,094
8242.136.112.0/20242.136.112.1 to 242.136.127.254242.136.127.2554,094
9242.136.128.0/20242.136.128.1 to 242.136.143.254242.136.143.2554,094
10242.136.144.0/20242.136.144.1 to 242.136.159.254242.136.159.2554,094
11242.136.160.0/20242.136.160.1 to 242.136.175.254242.136.175.2554,094
12242.136.176.0/20242.136.176.1 to 242.136.191.254242.136.191.2554,094
13242.136.192.0/20242.136.192.1 to 242.136.207.254242.136.207.2554,094
14242.136.208.0/20242.136.208.1 to 242.136.223.254242.136.223.2554,094
15242.136.224.0/20242.136.224.1 to 242.136.239.254242.136.239.2554,094
16242.136.240.0/20242.136.240.1 to 242.136.255.254242.136.255.2554,094
17242.137.0.0/20242.137.0.1 to 242.137.15.254242.137.15.2554,094
18242.137.16.0/20242.137.16.1 to 242.137.31.254242.137.31.2554,094
19242.137.32.0/20242.137.32.1 to 242.137.47.254242.137.47.2554,094
20242.137.48.0/20242.137.48.1 to 242.137.63.254242.137.63.2554,094
21242.137.64.0/20242.137.64.1 to 242.137.79.254242.137.79.2554,094
22242.137.80.0/20242.137.80.1 to 242.137.95.254242.137.95.2554,094
23242.137.96.0/20242.137.96.1 to 242.137.111.254242.137.111.2554,094
24242.137.112.0/20242.137.112.1 to 242.137.127.254242.137.127.2554,094
25242.137.128.0/20242.137.128.1 to 242.137.143.254242.137.143.2554,094
26242.137.144.0/20242.137.144.1 to 242.137.159.254242.137.159.2554,094
27242.137.160.0/20242.137.160.1 to 242.137.175.254242.137.175.2554,094
28242.137.176.0/20242.137.176.1 to 242.137.191.254242.137.191.2554,094
29242.137.192.0/20242.137.192.1 to 242.137.207.254242.137.207.2554,094
30242.137.208.0/20242.137.208.1 to 242.137.223.254242.137.223.2554,094
31242.137.224.0/20242.137.224.1 to 242.137.239.254242.137.239.2554,094
32242.137.240.0/20242.137.240.1 to 242.137.255.254242.137.255.2554,094
33242.138.0.0/20242.138.0.1 to 242.138.15.254242.138.15.2554,094
34242.138.16.0/20242.138.16.1 to 242.138.31.254242.138.31.2554,094
35242.138.32.0/20242.138.32.1 to 242.138.47.254242.138.47.2554,094
36242.138.48.0/20242.138.48.1 to 242.138.63.254242.138.63.2554,094
37242.138.64.0/20242.138.64.1 to 242.138.79.254242.138.79.2554,094
38242.138.80.0/20242.138.80.1 to 242.138.95.254242.138.95.2554,094
39242.138.96.0/20242.138.96.1 to 242.138.111.254242.138.111.2554,094
40242.138.112.0/20242.138.112.1 to 242.138.127.254242.138.127.2554,094
41242.138.128.0/20242.138.128.1 to 242.138.143.254242.138.143.2554,094
42242.138.144.0/20242.138.144.1 to 242.138.159.254242.138.159.2554,094
43242.138.160.0/20242.138.160.1 to 242.138.175.254242.138.175.2554,094
44242.138.176.0/20242.138.176.1 to 242.138.191.254242.138.191.2554,094
45242.138.192.0/20242.138.192.1 to 242.138.207.254242.138.207.2554,094
46242.138.208.0/20242.138.208.1 to 242.138.223.254242.138.223.2554,094
47242.138.224.0/20242.138.224.1 to 242.138.239.254242.138.239.2554,094
48242.138.240.0/20242.138.240.1 to 242.138.255.254242.138.255.2554,094
49242.139.0.0/20242.139.0.1 to 242.139.15.254242.139.15.2554,094
50242.139.16.0/20242.139.16.1 to 242.139.31.254242.139.31.2554,094
51242.139.32.0/20242.139.32.1 to 242.139.47.254242.139.47.2554,094
52242.139.48.0/20242.139.48.1 to 242.139.63.254242.139.63.2554,094
53242.139.64.0/20242.139.64.1 to 242.139.79.254242.139.79.2554,094
54242.139.80.0/20242.139.80.1 to 242.139.95.254242.139.95.2554,094
55242.139.96.0/20242.139.96.1 to 242.139.111.254242.139.111.2554,094
56242.139.112.0/20242.139.112.1 to 242.139.127.254242.139.127.2554,094
57242.139.128.0/20242.139.128.1 to 242.139.143.254242.139.143.2554,094
58242.139.144.0/20242.139.144.1 to 242.139.159.254242.139.159.2554,094
59242.139.160.0/20242.139.160.1 to 242.139.175.254242.139.175.2554,094
60242.139.176.0/20242.139.176.1 to 242.139.191.254242.139.191.2554,094
61242.139.192.0/20242.139.192.1 to 242.139.207.254242.139.207.2554,094
62242.139.208.0/20242.139.208.1 to 242.139.223.254242.139.223.2554,094
63242.139.224.0/20242.139.224.1 to 242.139.239.254242.139.239.2554,094
64242.139.240.0/20242.139.240.1 to 242.139.255.254242.139.255.2554,094

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.