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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.

Network166.167.0.0/16
Usable hosts65,534
Subnet mask255.255.0.0
Addresses65,536
Network address
166.167.0.0
Broadcast address
166.167.255.255
First usable
166.167.0.1
Last usable
166.167.255.254
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
Public public
Old class
B (default /16)
As numbers
Hex A6A70000 · Integer 2795962368 to 2796027903
Reverse DNS zone
167.166.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10100110.10100111..00000000.00000000166.167.0.0
Subnet mask11111111.11111111..00000000.00000000255.255.0.0
Network10100110.10100111..00000000.00000000166.167.0.0
Broadcast10100110.10100111..11111111.11111111166.167.255.255
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)

166.167.0.0/16 makes 64 subnets of /22.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1166.167.0.0/22166.167.0.1 to 166.167.3.254166.167.3.2551,022
2166.167.4.0/22166.167.4.1 to 166.167.7.254166.167.7.2551,022
3166.167.8.0/22166.167.8.1 to 166.167.11.254166.167.11.2551,022
4166.167.12.0/22166.167.12.1 to 166.167.15.254166.167.15.2551,022
5166.167.16.0/22166.167.16.1 to 166.167.19.254166.167.19.2551,022
6166.167.20.0/22166.167.20.1 to 166.167.23.254166.167.23.2551,022
7166.167.24.0/22166.167.24.1 to 166.167.27.254166.167.27.2551,022
8166.167.28.0/22166.167.28.1 to 166.167.31.254166.167.31.2551,022
9166.167.32.0/22166.167.32.1 to 166.167.35.254166.167.35.2551,022
10166.167.36.0/22166.167.36.1 to 166.167.39.254166.167.39.2551,022
11166.167.40.0/22166.167.40.1 to 166.167.43.254166.167.43.2551,022
12166.167.44.0/22166.167.44.1 to 166.167.47.254166.167.47.2551,022
13166.167.48.0/22166.167.48.1 to 166.167.51.254166.167.51.2551,022
14166.167.52.0/22166.167.52.1 to 166.167.55.254166.167.55.2551,022
15166.167.56.0/22166.167.56.1 to 166.167.59.254166.167.59.2551,022
16166.167.60.0/22166.167.60.1 to 166.167.63.254166.167.63.2551,022
17166.167.64.0/22166.167.64.1 to 166.167.67.254166.167.67.2551,022
18166.167.68.0/22166.167.68.1 to 166.167.71.254166.167.71.2551,022
19166.167.72.0/22166.167.72.1 to 166.167.75.254166.167.75.2551,022
20166.167.76.0/22166.167.76.1 to 166.167.79.254166.167.79.2551,022
21166.167.80.0/22166.167.80.1 to 166.167.83.254166.167.83.2551,022
22166.167.84.0/22166.167.84.1 to 166.167.87.254166.167.87.2551,022
23166.167.88.0/22166.167.88.1 to 166.167.91.254166.167.91.2551,022
24166.167.92.0/22166.167.92.1 to 166.167.95.254166.167.95.2551,022
25166.167.96.0/22166.167.96.1 to 166.167.99.254166.167.99.2551,022
26166.167.100.0/22166.167.100.1 to 166.167.103.254166.167.103.2551,022
27166.167.104.0/22166.167.104.1 to 166.167.107.254166.167.107.2551,022
28166.167.108.0/22166.167.108.1 to 166.167.111.254166.167.111.2551,022
29166.167.112.0/22166.167.112.1 to 166.167.115.254166.167.115.2551,022
30166.167.116.0/22166.167.116.1 to 166.167.119.254166.167.119.2551,022
31166.167.120.0/22166.167.120.1 to 166.167.123.254166.167.123.2551,022
32166.167.124.0/22166.167.124.1 to 166.167.127.254166.167.127.2551,022
33166.167.128.0/22166.167.128.1 to 166.167.131.254166.167.131.2551,022
34166.167.132.0/22166.167.132.1 to 166.167.135.254166.167.135.2551,022
35166.167.136.0/22166.167.136.1 to 166.167.139.254166.167.139.2551,022
36166.167.140.0/22166.167.140.1 to 166.167.143.254166.167.143.2551,022
37166.167.144.0/22166.167.144.1 to 166.167.147.254166.167.147.2551,022
38166.167.148.0/22166.167.148.1 to 166.167.151.254166.167.151.2551,022
39166.167.152.0/22166.167.152.1 to 166.167.155.254166.167.155.2551,022
40166.167.156.0/22166.167.156.1 to 166.167.159.254166.167.159.2551,022
41166.167.160.0/22166.167.160.1 to 166.167.163.254166.167.163.2551,022
42166.167.164.0/22166.167.164.1 to 166.167.167.254166.167.167.2551,022
43166.167.168.0/22166.167.168.1 to 166.167.171.254166.167.171.2551,022
44166.167.172.0/22166.167.172.1 to 166.167.175.254166.167.175.2551,022
45166.167.176.0/22166.167.176.1 to 166.167.179.254166.167.179.2551,022
46166.167.180.0/22166.167.180.1 to 166.167.183.254166.167.183.2551,022
47166.167.184.0/22166.167.184.1 to 166.167.187.254166.167.187.2551,022
48166.167.188.0/22166.167.188.1 to 166.167.191.254166.167.191.2551,022
49166.167.192.0/22166.167.192.1 to 166.167.195.254166.167.195.2551,022
50166.167.196.0/22166.167.196.1 to 166.167.199.254166.167.199.2551,022
51166.167.200.0/22166.167.200.1 to 166.167.203.254166.167.203.2551,022
52166.167.204.0/22166.167.204.1 to 166.167.207.254166.167.207.2551,022
53166.167.208.0/22166.167.208.1 to 166.167.211.254166.167.211.2551,022
54166.167.212.0/22166.167.212.1 to 166.167.215.254166.167.215.2551,022
55166.167.216.0/22166.167.216.1 to 166.167.219.254166.167.219.2551,022
56166.167.220.0/22166.167.220.1 to 166.167.223.254166.167.223.2551,022
57166.167.224.0/22166.167.224.1 to 166.167.227.254166.167.227.2551,022
58166.167.228.0/22166.167.228.1 to 166.167.231.254166.167.231.2551,022
59166.167.232.0/22166.167.232.1 to 166.167.235.254166.167.235.2551,022
60166.167.236.0/22166.167.236.1 to 166.167.239.254166.167.239.2551,022
61166.167.240.0/22166.167.240.1 to 166.167.243.254166.167.243.2551,022
62166.167.244.0/22166.167.244.1 to 166.167.247.254166.167.247.2551,022
63166.167.248.0/22166.167.248.1 to 166.167.251.254166.167.251.2551,022
64166.167.252.0/22166.167.252.1 to 166.167.255.254166.167.255.2551,022

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.