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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.

Network44.0.0.0/9
Usable hosts8,388,606
Subnet mask255.128.0.0
Addresses8,388,608
Network address
44.0.0.0
Broadcast address
44.127.255.255
First usable
44.0.0.1
Last usable
44.127.255.254
Usable hosts
8,388,606 (8,388,608 less the network and broadcast addresses)
Subnet mask
255.128.0.0
Wildcard mask
0.127.255.255 (Cisco ACLs, OSPF)
Prefix length
/9
Type
Public public
Old class
A (default /8)
As numbers
Hex 2C000000 · Integer 738197504 to 746586111
Reverse DNS zones
0.44.in-addr.arpa
1.44.in-addr.arpa
2.44.in-addr.arpa
3.44.in-addr.arpa
4.44.in-addr.arpa
5.44.in-addr.arpa
6.44.in-addr.arpa
7.44.in-addr.arpa
8.44.in-addr.arpa
9.44.in-addr.arpa
10.44.in-addr.arpa
11.44.in-addr.arpa
12.44.in-addr.arpa
13.44.in-addr.arpa
14.44.in-addr.arpa
15.44.in-addr.arpa
and 112 more
/9 is not on a 8-bit boundary, so it takes 128 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00101100.00000000.00000000.0000000044.0.0.0
Subnet mask11111111.10000000.00000000.00000000255.128.0.0
Network00101100.00000000.00000000.0000000044.0.0.0
Broadcast00101100.01111111.11111111.1111111144.127.255.255
Split into smaller subnets/15
/10 (2)/11 (4)/12 (8)/13 (16)/14 (32)/15 (64)/16 (128)/17 (256)/18 (512)/19 (1,024)/20 (2,048)/21 (4,096)

44.0.0.0/9 makes 64 subnets of /15.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
144.0.0.0/1544.0.0.1 to 44.1.255.25444.1.255.255131,070
244.2.0.0/1544.2.0.1 to 44.3.255.25444.3.255.255131,070
344.4.0.0/1544.4.0.1 to 44.5.255.25444.5.255.255131,070
444.6.0.0/1544.6.0.1 to 44.7.255.25444.7.255.255131,070
544.8.0.0/1544.8.0.1 to 44.9.255.25444.9.255.255131,070
644.10.0.0/1544.10.0.1 to 44.11.255.25444.11.255.255131,070
744.12.0.0/1544.12.0.1 to 44.13.255.25444.13.255.255131,070
844.14.0.0/1544.14.0.1 to 44.15.255.25444.15.255.255131,070
944.16.0.0/1544.16.0.1 to 44.17.255.25444.17.255.255131,070
1044.18.0.0/1544.18.0.1 to 44.19.255.25444.19.255.255131,070
1144.20.0.0/1544.20.0.1 to 44.21.255.25444.21.255.255131,070
1244.22.0.0/1544.22.0.1 to 44.23.255.25444.23.255.255131,070
1344.24.0.0/1544.24.0.1 to 44.25.255.25444.25.255.255131,070
1444.26.0.0/1544.26.0.1 to 44.27.255.25444.27.255.255131,070
1544.28.0.0/1544.28.0.1 to 44.29.255.25444.29.255.255131,070
1644.30.0.0/1544.30.0.1 to 44.31.255.25444.31.255.255131,070
1744.32.0.0/1544.32.0.1 to 44.33.255.25444.33.255.255131,070
1844.34.0.0/1544.34.0.1 to 44.35.255.25444.35.255.255131,070
1944.36.0.0/1544.36.0.1 to 44.37.255.25444.37.255.255131,070
2044.38.0.0/1544.38.0.1 to 44.39.255.25444.39.255.255131,070
2144.40.0.0/1544.40.0.1 to 44.41.255.25444.41.255.255131,070
2244.42.0.0/1544.42.0.1 to 44.43.255.25444.43.255.255131,070
2344.44.0.0/1544.44.0.1 to 44.45.255.25444.45.255.255131,070
2444.46.0.0/1544.46.0.1 to 44.47.255.25444.47.255.255131,070
2544.48.0.0/1544.48.0.1 to 44.49.255.25444.49.255.255131,070
2644.50.0.0/1544.50.0.1 to 44.51.255.25444.51.255.255131,070
2744.52.0.0/1544.52.0.1 to 44.53.255.25444.53.255.255131,070
2844.54.0.0/1544.54.0.1 to 44.55.255.25444.55.255.255131,070
2944.56.0.0/1544.56.0.1 to 44.57.255.25444.57.255.255131,070
3044.58.0.0/1544.58.0.1 to 44.59.255.25444.59.255.255131,070
3144.60.0.0/1544.60.0.1 to 44.61.255.25444.61.255.255131,070
3244.62.0.0/1544.62.0.1 to 44.63.255.25444.63.255.255131,070
3344.64.0.0/1544.64.0.1 to 44.65.255.25444.65.255.255131,070
3444.66.0.0/1544.66.0.1 to 44.67.255.25444.67.255.255131,070
3544.68.0.0/1544.68.0.1 to 44.69.255.25444.69.255.255131,070
3644.70.0.0/1544.70.0.1 to 44.71.255.25444.71.255.255131,070
3744.72.0.0/1544.72.0.1 to 44.73.255.25444.73.255.255131,070
3844.74.0.0/1544.74.0.1 to 44.75.255.25444.75.255.255131,070
3944.76.0.0/1544.76.0.1 to 44.77.255.25444.77.255.255131,070
4044.78.0.0/1544.78.0.1 to 44.79.255.25444.79.255.255131,070
4144.80.0.0/1544.80.0.1 to 44.81.255.25444.81.255.255131,070
4244.82.0.0/1544.82.0.1 to 44.83.255.25444.83.255.255131,070
4344.84.0.0/1544.84.0.1 to 44.85.255.25444.85.255.255131,070
4444.86.0.0/1544.86.0.1 to 44.87.255.25444.87.255.255131,070
4544.88.0.0/1544.88.0.1 to 44.89.255.25444.89.255.255131,070
4644.90.0.0/1544.90.0.1 to 44.91.255.25444.91.255.255131,070
4744.92.0.0/1544.92.0.1 to 44.93.255.25444.93.255.255131,070
4844.94.0.0/1544.94.0.1 to 44.95.255.25444.95.255.255131,070
4944.96.0.0/1544.96.0.1 to 44.97.255.25444.97.255.255131,070
5044.98.0.0/1544.98.0.1 to 44.99.255.25444.99.255.255131,070
5144.100.0.0/1544.100.0.1 to 44.101.255.25444.101.255.255131,070
5244.102.0.0/1544.102.0.1 to 44.103.255.25444.103.255.255131,070
5344.104.0.0/1544.104.0.1 to 44.105.255.25444.105.255.255131,070
5444.106.0.0/1544.106.0.1 to 44.107.255.25444.107.255.255131,070
5544.108.0.0/1544.108.0.1 to 44.109.255.25444.109.255.255131,070
5644.110.0.0/1544.110.0.1 to 44.111.255.25444.111.255.255131,070
5744.112.0.0/1544.112.0.1 to 44.113.255.25444.113.255.255131,070
5844.114.0.0/1544.114.0.1 to 44.115.255.25444.115.255.255131,070
5944.116.0.0/1544.116.0.1 to 44.117.255.25444.117.255.255131,070
6044.118.0.0/1544.118.0.1 to 44.119.255.25444.119.255.255131,070
6144.120.0.0/1544.120.0.1 to 44.121.255.25444.121.255.255131,070
6244.122.0.0/1544.122.0.1 to 44.123.255.25444.123.255.255131,070
6344.124.0.0/1544.124.0.1 to 44.125.255.25444.125.255.255131,070
6444.126.0.0/1544.126.0.1 to 44.127.255.25444.127.255.255131,070

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.