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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.

Network233.2.0.0/16
Usable hosts65,534
Subnet mask255.255.0.0
Addresses65,536
Network address
233.2.0.0
Broadcast address
233.2.255.255
First usable
233.2.0.1
Last usable
233.2.255.254
Usable hosts
65,534 (65,536 less the network and broadcast addresses)
Subnet mask
255.255.0.0
Wildcard mask
0.0.255.255 (Cisco ACLs, OSPF)
Prefix length
/16
Type
Multicast 224.0.0.0/4
One-to-many traffic, such as IPTV and routing protocols
Old class
D (multicast)
As numbers
Hex E9020000 · Integer 3909222400 to 3909287935
Reverse DNS zone
2.233.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11101001.00000010..00000000.00000000233.2.0.0
Subnet mask11111111.11111111..00000000.00000000255.255.0.0
Network11101001.00000010..00000000.00000000233.2.0.0
Broadcast11101001.00000010..11111111.11111111233.2.255.255
Split into smaller subnets/22
/17 (2)/18 (4)/19 (8)/20 (16)/21 (32)/22 (64)/23 (128)/24 (256)/25 (512)/26 (1,024)/27 (2,048)/28 (4,096)

233.2.0.0/16 makes 64 subnets of /22.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1233.2.0.0/22233.2.0.1 to 233.2.3.254233.2.3.2551,022
2233.2.4.0/22233.2.4.1 to 233.2.7.254233.2.7.2551,022
3233.2.8.0/22233.2.8.1 to 233.2.11.254233.2.11.2551,022
4233.2.12.0/22233.2.12.1 to 233.2.15.254233.2.15.2551,022
5233.2.16.0/22233.2.16.1 to 233.2.19.254233.2.19.2551,022
6233.2.20.0/22233.2.20.1 to 233.2.23.254233.2.23.2551,022
7233.2.24.0/22233.2.24.1 to 233.2.27.254233.2.27.2551,022
8233.2.28.0/22233.2.28.1 to 233.2.31.254233.2.31.2551,022
9233.2.32.0/22233.2.32.1 to 233.2.35.254233.2.35.2551,022
10233.2.36.0/22233.2.36.1 to 233.2.39.254233.2.39.2551,022
11233.2.40.0/22233.2.40.1 to 233.2.43.254233.2.43.2551,022
12233.2.44.0/22233.2.44.1 to 233.2.47.254233.2.47.2551,022
13233.2.48.0/22233.2.48.1 to 233.2.51.254233.2.51.2551,022
14233.2.52.0/22233.2.52.1 to 233.2.55.254233.2.55.2551,022
15233.2.56.0/22233.2.56.1 to 233.2.59.254233.2.59.2551,022
16233.2.60.0/22233.2.60.1 to 233.2.63.254233.2.63.2551,022
17233.2.64.0/22233.2.64.1 to 233.2.67.254233.2.67.2551,022
18233.2.68.0/22233.2.68.1 to 233.2.71.254233.2.71.2551,022
19233.2.72.0/22233.2.72.1 to 233.2.75.254233.2.75.2551,022
20233.2.76.0/22233.2.76.1 to 233.2.79.254233.2.79.2551,022
21233.2.80.0/22233.2.80.1 to 233.2.83.254233.2.83.2551,022
22233.2.84.0/22233.2.84.1 to 233.2.87.254233.2.87.2551,022
23233.2.88.0/22233.2.88.1 to 233.2.91.254233.2.91.2551,022
24233.2.92.0/22233.2.92.1 to 233.2.95.254233.2.95.2551,022
25233.2.96.0/22233.2.96.1 to 233.2.99.254233.2.99.2551,022
26233.2.100.0/22233.2.100.1 to 233.2.103.254233.2.103.2551,022
27233.2.104.0/22233.2.104.1 to 233.2.107.254233.2.107.2551,022
28233.2.108.0/22233.2.108.1 to 233.2.111.254233.2.111.2551,022
29233.2.112.0/22233.2.112.1 to 233.2.115.254233.2.115.2551,022
30233.2.116.0/22233.2.116.1 to 233.2.119.254233.2.119.2551,022
31233.2.120.0/22233.2.120.1 to 233.2.123.254233.2.123.2551,022
32233.2.124.0/22233.2.124.1 to 233.2.127.254233.2.127.2551,022
33233.2.128.0/22233.2.128.1 to 233.2.131.254233.2.131.2551,022
34233.2.132.0/22233.2.132.1 to 233.2.135.254233.2.135.2551,022
35233.2.136.0/22233.2.136.1 to 233.2.139.254233.2.139.2551,022
36233.2.140.0/22233.2.140.1 to 233.2.143.254233.2.143.2551,022
37233.2.144.0/22233.2.144.1 to 233.2.147.254233.2.147.2551,022
38233.2.148.0/22233.2.148.1 to 233.2.151.254233.2.151.2551,022
39233.2.152.0/22233.2.152.1 to 233.2.155.254233.2.155.2551,022
40233.2.156.0/22233.2.156.1 to 233.2.159.254233.2.159.2551,022
41233.2.160.0/22233.2.160.1 to 233.2.163.254233.2.163.2551,022
42233.2.164.0/22233.2.164.1 to 233.2.167.254233.2.167.2551,022
43233.2.168.0/22233.2.168.1 to 233.2.171.254233.2.171.2551,022
44233.2.172.0/22233.2.172.1 to 233.2.175.254233.2.175.2551,022
45233.2.176.0/22233.2.176.1 to 233.2.179.254233.2.179.2551,022
46233.2.180.0/22233.2.180.1 to 233.2.183.254233.2.183.2551,022
47233.2.184.0/22233.2.184.1 to 233.2.187.254233.2.187.2551,022
48233.2.188.0/22233.2.188.1 to 233.2.191.254233.2.191.2551,022
49233.2.192.0/22233.2.192.1 to 233.2.195.254233.2.195.2551,022
50233.2.196.0/22233.2.196.1 to 233.2.199.254233.2.199.2551,022
51233.2.200.0/22233.2.200.1 to 233.2.203.254233.2.203.2551,022
52233.2.204.0/22233.2.204.1 to 233.2.207.254233.2.207.2551,022
53233.2.208.0/22233.2.208.1 to 233.2.211.254233.2.211.2551,022
54233.2.212.0/22233.2.212.1 to 233.2.215.254233.2.215.2551,022
55233.2.216.0/22233.2.216.1 to 233.2.219.254233.2.219.2551,022
56233.2.220.0/22233.2.220.1 to 233.2.223.254233.2.223.2551,022
57233.2.224.0/22233.2.224.1 to 233.2.227.254233.2.227.2551,022
58233.2.228.0/22233.2.228.1 to 233.2.231.254233.2.231.2551,022
59233.2.232.0/22233.2.232.1 to 233.2.235.254233.2.235.2551,022
60233.2.236.0/22233.2.236.1 to 233.2.239.254233.2.239.2551,022
61233.2.240.0/22233.2.240.1 to 233.2.243.254233.2.243.2551,022
62233.2.244.0/22233.2.244.1 to 233.2.247.254233.2.247.2551,022
63233.2.248.0/22233.2.248.1 to 233.2.251.254233.2.251.2551,022
64233.2.252.0/22233.2.252.1 to 233.2.255.254233.2.255.2551,022

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.