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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.

Network224.160.0.0/12
Usable hosts1,048,574
Subnet mask255.240.0.0
Addresses1,048,576
Network address
224.160.0.0
Broadcast address
224.175.255.255
First usable
224.160.0.1
Last usable
224.175.255.254
Usable hosts
1,048,574 (1,048,576 less the network and broadcast addresses)
Subnet mask
255.240.0.0
Wildcard mask
0.15.255.255 (Cisco ACLs, OSPF)
Prefix length
/12
Type
Multicast 224.0.0.0/4
One-to-many traffic, such as IPTV and routing protocols
Old class
D (multicast)
As numbers
Hex E0A00000 · Integer 3768582144 to 3769630719
Reverse DNS zones
160.224.in-addr.arpa
161.224.in-addr.arpa
162.224.in-addr.arpa
163.224.in-addr.arpa
164.224.in-addr.arpa
165.224.in-addr.arpa
166.224.in-addr.arpa
167.224.in-addr.arpa
168.224.in-addr.arpa
169.224.in-addr.arpa
170.224.in-addr.arpa
171.224.in-addr.arpa
172.224.in-addr.arpa
173.224.in-addr.arpa
174.224.in-addr.arpa
175.224.in-addr.arpa
/12 is not on a 8-bit boundary, so it takes 16 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11100000.10100000.00000000.00000000224.160.0.0
Subnet mask11111111.11110000.00000000.00000000255.240.0.0
Network11100000.10100000.00000000.00000000224.160.0.0
Broadcast11100000.10101111.11111111.11111111224.175.255.255
Split into smaller subnets/18
/13 (2)/14 (4)/15 (8)/16 (16)/17 (32)/18 (64)/19 (128)/20 (256)/21 (512)/22 (1,024)/23 (2,048)/24 (4,096)

224.160.0.0/12 makes 64 subnets of /18.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1224.160.0.0/18224.160.0.1 to 224.160.63.254224.160.63.25516,382
2224.160.64.0/18224.160.64.1 to 224.160.127.254224.160.127.25516,382
3224.160.128.0/18224.160.128.1 to 224.160.191.254224.160.191.25516,382
4224.160.192.0/18224.160.192.1 to 224.160.255.254224.160.255.25516,382
5224.161.0.0/18224.161.0.1 to 224.161.63.254224.161.63.25516,382
6224.161.64.0/18224.161.64.1 to 224.161.127.254224.161.127.25516,382
7224.161.128.0/18224.161.128.1 to 224.161.191.254224.161.191.25516,382
8224.161.192.0/18224.161.192.1 to 224.161.255.254224.161.255.25516,382
9224.162.0.0/18224.162.0.1 to 224.162.63.254224.162.63.25516,382
10224.162.64.0/18224.162.64.1 to 224.162.127.254224.162.127.25516,382
11224.162.128.0/18224.162.128.1 to 224.162.191.254224.162.191.25516,382
12224.162.192.0/18224.162.192.1 to 224.162.255.254224.162.255.25516,382
13224.163.0.0/18224.163.0.1 to 224.163.63.254224.163.63.25516,382
14224.163.64.0/18224.163.64.1 to 224.163.127.254224.163.127.25516,382
15224.163.128.0/18224.163.128.1 to 224.163.191.254224.163.191.25516,382
16224.163.192.0/18224.163.192.1 to 224.163.255.254224.163.255.25516,382
17224.164.0.0/18224.164.0.1 to 224.164.63.254224.164.63.25516,382
18224.164.64.0/18224.164.64.1 to 224.164.127.254224.164.127.25516,382
19224.164.128.0/18224.164.128.1 to 224.164.191.254224.164.191.25516,382
20224.164.192.0/18224.164.192.1 to 224.164.255.254224.164.255.25516,382
21224.165.0.0/18224.165.0.1 to 224.165.63.254224.165.63.25516,382
22224.165.64.0/18224.165.64.1 to 224.165.127.254224.165.127.25516,382
23224.165.128.0/18224.165.128.1 to 224.165.191.254224.165.191.25516,382
24224.165.192.0/18224.165.192.1 to 224.165.255.254224.165.255.25516,382
25224.166.0.0/18224.166.0.1 to 224.166.63.254224.166.63.25516,382
26224.166.64.0/18224.166.64.1 to 224.166.127.254224.166.127.25516,382
27224.166.128.0/18224.166.128.1 to 224.166.191.254224.166.191.25516,382
28224.166.192.0/18224.166.192.1 to 224.166.255.254224.166.255.25516,382
29224.167.0.0/18224.167.0.1 to 224.167.63.254224.167.63.25516,382
30224.167.64.0/18224.167.64.1 to 224.167.127.254224.167.127.25516,382
31224.167.128.0/18224.167.128.1 to 224.167.191.254224.167.191.25516,382
32224.167.192.0/18224.167.192.1 to 224.167.255.254224.167.255.25516,382
33224.168.0.0/18224.168.0.1 to 224.168.63.254224.168.63.25516,382
34224.168.64.0/18224.168.64.1 to 224.168.127.254224.168.127.25516,382
35224.168.128.0/18224.168.128.1 to 224.168.191.254224.168.191.25516,382
36224.168.192.0/18224.168.192.1 to 224.168.255.254224.168.255.25516,382
37224.169.0.0/18224.169.0.1 to 224.169.63.254224.169.63.25516,382
38224.169.64.0/18224.169.64.1 to 224.169.127.254224.169.127.25516,382
39224.169.128.0/18224.169.128.1 to 224.169.191.254224.169.191.25516,382
40224.169.192.0/18224.169.192.1 to 224.169.255.254224.169.255.25516,382
41224.170.0.0/18224.170.0.1 to 224.170.63.254224.170.63.25516,382
42224.170.64.0/18224.170.64.1 to 224.170.127.254224.170.127.25516,382
43224.170.128.0/18224.170.128.1 to 224.170.191.254224.170.191.25516,382
44224.170.192.0/18224.170.192.1 to 224.170.255.254224.170.255.25516,382
45224.171.0.0/18224.171.0.1 to 224.171.63.254224.171.63.25516,382
46224.171.64.0/18224.171.64.1 to 224.171.127.254224.171.127.25516,382
47224.171.128.0/18224.171.128.1 to 224.171.191.254224.171.191.25516,382
48224.171.192.0/18224.171.192.1 to 224.171.255.254224.171.255.25516,382
49224.172.0.0/18224.172.0.1 to 224.172.63.254224.172.63.25516,382
50224.172.64.0/18224.172.64.1 to 224.172.127.254224.172.127.25516,382
51224.172.128.0/18224.172.128.1 to 224.172.191.254224.172.191.25516,382
52224.172.192.0/18224.172.192.1 to 224.172.255.254224.172.255.25516,382
53224.173.0.0/18224.173.0.1 to 224.173.63.254224.173.63.25516,382
54224.173.64.0/18224.173.64.1 to 224.173.127.254224.173.127.25516,382
55224.173.128.0/18224.173.128.1 to 224.173.191.254224.173.191.25516,382
56224.173.192.0/18224.173.192.1 to 224.173.255.254224.173.255.25516,382
57224.174.0.0/18224.174.0.1 to 224.174.63.254224.174.63.25516,382
58224.174.64.0/18224.174.64.1 to 224.174.127.254224.174.127.25516,382
59224.174.128.0/18224.174.128.1 to 224.174.191.254224.174.191.25516,382
60224.174.192.0/18224.174.192.1 to 224.174.255.254224.174.255.25516,382
61224.175.0.0/18224.175.0.1 to 224.175.63.254224.175.63.25516,382
62224.175.64.0/18224.175.64.1 to 224.175.127.254224.175.127.25516,382
63224.175.128.0/18224.175.128.1 to 224.175.191.254224.175.191.25516,382
64224.175.192.0/18224.175.192.1 to 224.175.255.254224.175.255.25516,382

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.