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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.

Network38.4.0.0/14
Usable hosts262,142
Subnet mask255.252.0.0
Addresses262,144
Network address
38.4.0.0
Broadcast address
38.7.255.255
First usable
38.4.0.1
Last usable
38.7.255.254
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
Public public
Old class
A (default /8)
As numbers
Hex 26040000 · Integer 637796352 to 638058495
Reverse DNS zones
4.38.in-addr.arpa
5.38.in-addr.arpa
6.38.in-addr.arpa
7.38.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
Address00100110.00000100.00000000.0000000038.4.0.0
Subnet mask11111111.11111100.00000000.00000000255.252.0.0
Network00100110.00000100.00000000.0000000038.4.0.0
Broadcast00100110.00000111.11111111.1111111138.7.255.255
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)

38.4.0.0/14 makes 64 subnets of /20.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
138.4.0.0/2038.4.0.1 to 38.4.15.25438.4.15.2554,094
238.4.16.0/2038.4.16.1 to 38.4.31.25438.4.31.2554,094
338.4.32.0/2038.4.32.1 to 38.4.47.25438.4.47.2554,094
438.4.48.0/2038.4.48.1 to 38.4.63.25438.4.63.2554,094
538.4.64.0/2038.4.64.1 to 38.4.79.25438.4.79.2554,094
638.4.80.0/2038.4.80.1 to 38.4.95.25438.4.95.2554,094
738.4.96.0/2038.4.96.1 to 38.4.111.25438.4.111.2554,094
838.4.112.0/2038.4.112.1 to 38.4.127.25438.4.127.2554,094
938.4.128.0/2038.4.128.1 to 38.4.143.25438.4.143.2554,094
1038.4.144.0/2038.4.144.1 to 38.4.159.25438.4.159.2554,094
1138.4.160.0/2038.4.160.1 to 38.4.175.25438.4.175.2554,094
1238.4.176.0/2038.4.176.1 to 38.4.191.25438.4.191.2554,094
1338.4.192.0/2038.4.192.1 to 38.4.207.25438.4.207.2554,094
1438.4.208.0/2038.4.208.1 to 38.4.223.25438.4.223.2554,094
1538.4.224.0/2038.4.224.1 to 38.4.239.25438.4.239.2554,094
1638.4.240.0/2038.4.240.1 to 38.4.255.25438.4.255.2554,094
1738.5.0.0/2038.5.0.1 to 38.5.15.25438.5.15.2554,094
1838.5.16.0/2038.5.16.1 to 38.5.31.25438.5.31.2554,094
1938.5.32.0/2038.5.32.1 to 38.5.47.25438.5.47.2554,094
2038.5.48.0/2038.5.48.1 to 38.5.63.25438.5.63.2554,094
2138.5.64.0/2038.5.64.1 to 38.5.79.25438.5.79.2554,094
2238.5.80.0/2038.5.80.1 to 38.5.95.25438.5.95.2554,094
2338.5.96.0/2038.5.96.1 to 38.5.111.25438.5.111.2554,094
2438.5.112.0/2038.5.112.1 to 38.5.127.25438.5.127.2554,094
2538.5.128.0/2038.5.128.1 to 38.5.143.25438.5.143.2554,094
2638.5.144.0/2038.5.144.1 to 38.5.159.25438.5.159.2554,094
2738.5.160.0/2038.5.160.1 to 38.5.175.25438.5.175.2554,094
2838.5.176.0/2038.5.176.1 to 38.5.191.25438.5.191.2554,094
2938.5.192.0/2038.5.192.1 to 38.5.207.25438.5.207.2554,094
3038.5.208.0/2038.5.208.1 to 38.5.223.25438.5.223.2554,094
3138.5.224.0/2038.5.224.1 to 38.5.239.25438.5.239.2554,094
3238.5.240.0/2038.5.240.1 to 38.5.255.25438.5.255.2554,094
3338.6.0.0/2038.6.0.1 to 38.6.15.25438.6.15.2554,094
3438.6.16.0/2038.6.16.1 to 38.6.31.25438.6.31.2554,094
3538.6.32.0/2038.6.32.1 to 38.6.47.25438.6.47.2554,094
3638.6.48.0/2038.6.48.1 to 38.6.63.25438.6.63.2554,094
3738.6.64.0/2038.6.64.1 to 38.6.79.25438.6.79.2554,094
3838.6.80.0/2038.6.80.1 to 38.6.95.25438.6.95.2554,094
3938.6.96.0/2038.6.96.1 to 38.6.111.25438.6.111.2554,094
4038.6.112.0/2038.6.112.1 to 38.6.127.25438.6.127.2554,094
4138.6.128.0/2038.6.128.1 to 38.6.143.25438.6.143.2554,094
4238.6.144.0/2038.6.144.1 to 38.6.159.25438.6.159.2554,094
4338.6.160.0/2038.6.160.1 to 38.6.175.25438.6.175.2554,094
4438.6.176.0/2038.6.176.1 to 38.6.191.25438.6.191.2554,094
4538.6.192.0/2038.6.192.1 to 38.6.207.25438.6.207.2554,094
4638.6.208.0/2038.6.208.1 to 38.6.223.25438.6.223.2554,094
4738.6.224.0/2038.6.224.1 to 38.6.239.25438.6.239.2554,094
4838.6.240.0/2038.6.240.1 to 38.6.255.25438.6.255.2554,094
4938.7.0.0/2038.7.0.1 to 38.7.15.25438.7.15.2554,094
5038.7.16.0/2038.7.16.1 to 38.7.31.25438.7.31.2554,094
5138.7.32.0/2038.7.32.1 to 38.7.47.25438.7.47.2554,094
5238.7.48.0/2038.7.48.1 to 38.7.63.25438.7.63.2554,094
5338.7.64.0/2038.7.64.1 to 38.7.79.25438.7.79.2554,094
5438.7.80.0/2038.7.80.1 to 38.7.95.25438.7.95.2554,094
5538.7.96.0/2038.7.96.1 to 38.7.111.25438.7.111.2554,094
5638.7.112.0/2038.7.112.1 to 38.7.127.25438.7.127.2554,094
5738.7.128.0/2038.7.128.1 to 38.7.143.25438.7.143.2554,094
5838.7.144.0/2038.7.144.1 to 38.7.159.25438.7.159.2554,094
5938.7.160.0/2038.7.160.1 to 38.7.175.25438.7.175.2554,094
6038.7.176.0/2038.7.176.1 to 38.7.191.25438.7.191.2554,094
6138.7.192.0/2038.7.192.1 to 38.7.207.25438.7.207.2554,094
6238.7.208.0/2038.7.208.1 to 38.7.223.25438.7.223.2554,094
6338.7.224.0/2038.7.224.1 to 38.7.239.25438.7.239.2554,094
6438.7.240.0/2038.7.240.1 to 38.7.255.25438.7.255.2554,094

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.