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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.

Network66.167.2.192/26
Usable hosts62
Subnet mask255.255.255.192
Addresses64
Network address
66.167.2.192
Broadcast address
66.167.2.255
First usable
66.167.2.193
Last usable
66.167.2.254
Usable hosts
62 (64 less the network and broadcast addresses)
Subnet mask
255.255.255.192
Wildcard mask
0.0.0.63 (Cisco ACLs, OSPF)
Prefix length
/26
Type
Public public
Old class
A (default /8)
As numbers
Hex 42A702C0 · Integer 1118241472 to 1118241535
Reverse DNS zone
2.167.66.in-addr.arpa
Smaller than a /24: the provider delegates it inside the /24 zone (RFC 2317), or sets each PTR record for you.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01000010.10100111.00000010.1100000066.167.2.192
Subnet mask11111111.11111111.11111111.11000000255.255.255.192
Network01000010.10100111.00000010.1100000066.167.2.192
Broadcast01000010.10100111.00000010.1111111166.167.2.255
Split into smaller subnets/32
/27 (2)/28 (4)/29 (8)/30 (16)/31 (32)/32 (64)

66.167.2.192/26 makes 64 subnets of /32.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
166.167.2.192/3266.167.2.192 to 66.167.2.192—1
266.167.2.193/3266.167.2.193 to 66.167.2.193—1
366.167.2.194/3266.167.2.194 to 66.167.2.194—1
466.167.2.195/3266.167.2.195 to 66.167.2.195—1
566.167.2.196/3266.167.2.196 to 66.167.2.196—1
666.167.2.197/3266.167.2.197 to 66.167.2.197—1
766.167.2.198/3266.167.2.198 to 66.167.2.198—1
866.167.2.199/3266.167.2.199 to 66.167.2.199—1
966.167.2.200/3266.167.2.200 to 66.167.2.200—1
1066.167.2.201/3266.167.2.201 to 66.167.2.201—1
1166.167.2.202/3266.167.2.202 to 66.167.2.202—1
1266.167.2.203/3266.167.2.203 to 66.167.2.203—1
1366.167.2.204/3266.167.2.204 to 66.167.2.204—1
1466.167.2.205/3266.167.2.205 to 66.167.2.205—1
1566.167.2.206/3266.167.2.206 to 66.167.2.206—1
1666.167.2.207/3266.167.2.207 to 66.167.2.207—1
1766.167.2.208/3266.167.2.208 to 66.167.2.208—1
1866.167.2.209/3266.167.2.209 to 66.167.2.209—1
1966.167.2.210/3266.167.2.210 to 66.167.2.210—1
2066.167.2.211/3266.167.2.211 to 66.167.2.211—1
2166.167.2.212/3266.167.2.212 to 66.167.2.212—1
2266.167.2.213/3266.167.2.213 to 66.167.2.213—1
2366.167.2.214/3266.167.2.214 to 66.167.2.214—1
2466.167.2.215/3266.167.2.215 to 66.167.2.215—1
2566.167.2.216/3266.167.2.216 to 66.167.2.216—1
2666.167.2.217/3266.167.2.217 to 66.167.2.217—1
2766.167.2.218/3266.167.2.218 to 66.167.2.218—1
2866.167.2.219/3266.167.2.219 to 66.167.2.219—1
2966.167.2.220/3266.167.2.220 to 66.167.2.220—1
3066.167.2.221/3266.167.2.221 to 66.167.2.221—1
3166.167.2.222/3266.167.2.222 to 66.167.2.222—1
3266.167.2.223/3266.167.2.223 to 66.167.2.223—1
3366.167.2.224/3266.167.2.224 to 66.167.2.224—1
3466.167.2.225/3266.167.2.225 to 66.167.2.225—1
3566.167.2.226/3266.167.2.226 to 66.167.2.226—1
3666.167.2.227/3266.167.2.227 to 66.167.2.227—1
3766.167.2.228/3266.167.2.228 to 66.167.2.228—1
3866.167.2.229/3266.167.2.229 to 66.167.2.229—1
3966.167.2.230/3266.167.2.230 to 66.167.2.230—1
4066.167.2.231/3266.167.2.231 to 66.167.2.231—1
4166.167.2.232/3266.167.2.232 to 66.167.2.232—1
4266.167.2.233/3266.167.2.233 to 66.167.2.233—1
4366.167.2.234/3266.167.2.234 to 66.167.2.234—1
4466.167.2.235/3266.167.2.235 to 66.167.2.235—1
4566.167.2.236/3266.167.2.236 to 66.167.2.236—1
4666.167.2.237/3266.167.2.237 to 66.167.2.237—1
4766.167.2.238/3266.167.2.238 to 66.167.2.238—1
4866.167.2.239/3266.167.2.239 to 66.167.2.239—1
4966.167.2.240/3266.167.2.240 to 66.167.2.240—1
5066.167.2.241/3266.167.2.241 to 66.167.2.241—1
5166.167.2.242/3266.167.2.242 to 66.167.2.242—1
5266.167.2.243/3266.167.2.243 to 66.167.2.243—1
5366.167.2.244/3266.167.2.244 to 66.167.2.244—1
5466.167.2.245/3266.167.2.245 to 66.167.2.245—1
5566.167.2.246/3266.167.2.246 to 66.167.2.246—1
5666.167.2.247/3266.167.2.247 to 66.167.2.247—1
5766.167.2.248/3266.167.2.248 to 66.167.2.248—1
5866.167.2.249/3266.167.2.249 to 66.167.2.249—1
5966.167.2.250/3266.167.2.250 to 66.167.2.250—1
6066.167.2.251/3266.167.2.251 to 66.167.2.251—1
6166.167.2.252/3266.167.2.252 to 66.167.2.252—1
6266.167.2.253/3266.167.2.253 to 66.167.2.253—1
6366.167.2.254/3266.167.2.254 to 66.167.2.254—1
6466.167.2.255/3266.167.2.255 to 66.167.2.255—1

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.