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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.

Network23.192.0.0/11
Usable hosts2,097,150
Subnet mask255.224.0.0
Addresses2,097,152
Network address
23.192.0.0
Broadcast address
23.223.255.255
First usable
23.192.0.1
Last usable
23.223.255.254
Usable hosts
2,097,150 (2,097,152 less the network and broadcast addresses)
Subnet mask
255.224.0.0
Wildcard mask
0.31.255.255 (Cisco ACLs, OSPF)
Prefix length
/11
Type
Public public
Old class
A (default /8)
As numbers
Hex 17C00000 · Integer 398458880 to 400556031
Reverse DNS zones
192.23.in-addr.arpa
193.23.in-addr.arpa
194.23.in-addr.arpa
195.23.in-addr.arpa
196.23.in-addr.arpa
197.23.in-addr.arpa
198.23.in-addr.arpa
199.23.in-addr.arpa
200.23.in-addr.arpa
201.23.in-addr.arpa
202.23.in-addr.arpa
203.23.in-addr.arpa
204.23.in-addr.arpa
205.23.in-addr.arpa
206.23.in-addr.arpa
207.23.in-addr.arpa
and 16 more
/11 is not on a 8-bit boundary, so it takes 32 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00010111.11000000.00000000.0000000023.192.0.0
Subnet mask11111111.11100000.00000000.00000000255.224.0.0
Network00010111.11000000.00000000.0000000023.192.0.0
Broadcast00010111.11011111.11111111.1111111123.223.255.255
Split into smaller subnets/17
/12 (2)/13 (4)/14 (8)/15 (16)/16 (32)/17 (64)/18 (128)/19 (256)/20 (512)/21 (1,024)/22 (2,048)/23 (4,096)

23.192.0.0/11 makes 64 subnets of /17.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
123.192.0.0/1723.192.0.1 to 23.192.127.25423.192.127.25532,766
223.192.128.0/1723.192.128.1 to 23.192.255.25423.192.255.25532,766
323.193.0.0/1723.193.0.1 to 23.193.127.25423.193.127.25532,766
423.193.128.0/1723.193.128.1 to 23.193.255.25423.193.255.25532,766
523.194.0.0/1723.194.0.1 to 23.194.127.25423.194.127.25532,766
623.194.128.0/1723.194.128.1 to 23.194.255.25423.194.255.25532,766
723.195.0.0/1723.195.0.1 to 23.195.127.25423.195.127.25532,766
823.195.128.0/1723.195.128.1 to 23.195.255.25423.195.255.25532,766
923.196.0.0/1723.196.0.1 to 23.196.127.25423.196.127.25532,766
1023.196.128.0/1723.196.128.1 to 23.196.255.25423.196.255.25532,766
1123.197.0.0/1723.197.0.1 to 23.197.127.25423.197.127.25532,766
1223.197.128.0/1723.197.128.1 to 23.197.255.25423.197.255.25532,766
1323.198.0.0/1723.198.0.1 to 23.198.127.25423.198.127.25532,766
1423.198.128.0/1723.198.128.1 to 23.198.255.25423.198.255.25532,766
1523.199.0.0/1723.199.0.1 to 23.199.127.25423.199.127.25532,766
1623.199.128.0/1723.199.128.1 to 23.199.255.25423.199.255.25532,766
1723.200.0.0/1723.200.0.1 to 23.200.127.25423.200.127.25532,766
1823.200.128.0/1723.200.128.1 to 23.200.255.25423.200.255.25532,766
1923.201.0.0/1723.201.0.1 to 23.201.127.25423.201.127.25532,766
2023.201.128.0/1723.201.128.1 to 23.201.255.25423.201.255.25532,766
2123.202.0.0/1723.202.0.1 to 23.202.127.25423.202.127.25532,766
2223.202.128.0/1723.202.128.1 to 23.202.255.25423.202.255.25532,766
2323.203.0.0/1723.203.0.1 to 23.203.127.25423.203.127.25532,766
2423.203.128.0/1723.203.128.1 to 23.203.255.25423.203.255.25532,766
2523.204.0.0/1723.204.0.1 to 23.204.127.25423.204.127.25532,766
2623.204.128.0/1723.204.128.1 to 23.204.255.25423.204.255.25532,766
2723.205.0.0/1723.205.0.1 to 23.205.127.25423.205.127.25532,766
2823.205.128.0/1723.205.128.1 to 23.205.255.25423.205.255.25532,766
2923.206.0.0/1723.206.0.1 to 23.206.127.25423.206.127.25532,766
3023.206.128.0/1723.206.128.1 to 23.206.255.25423.206.255.25532,766
3123.207.0.0/1723.207.0.1 to 23.207.127.25423.207.127.25532,766
3223.207.128.0/1723.207.128.1 to 23.207.255.25423.207.255.25532,766
3323.208.0.0/1723.208.0.1 to 23.208.127.25423.208.127.25532,766
3423.208.128.0/1723.208.128.1 to 23.208.255.25423.208.255.25532,766
3523.209.0.0/1723.209.0.1 to 23.209.127.25423.209.127.25532,766
3623.209.128.0/1723.209.128.1 to 23.209.255.25423.209.255.25532,766
3723.210.0.0/1723.210.0.1 to 23.210.127.25423.210.127.25532,766
3823.210.128.0/1723.210.128.1 to 23.210.255.25423.210.255.25532,766
3923.211.0.0/1723.211.0.1 to 23.211.127.25423.211.127.25532,766
4023.211.128.0/1723.211.128.1 to 23.211.255.25423.211.255.25532,766
4123.212.0.0/1723.212.0.1 to 23.212.127.25423.212.127.25532,766
4223.212.128.0/1723.212.128.1 to 23.212.255.25423.212.255.25532,766
4323.213.0.0/1723.213.0.1 to 23.213.127.25423.213.127.25532,766
4423.213.128.0/1723.213.128.1 to 23.213.255.25423.213.255.25532,766
4523.214.0.0/1723.214.0.1 to 23.214.127.25423.214.127.25532,766
4623.214.128.0/1723.214.128.1 to 23.214.255.25423.214.255.25532,766
4723.215.0.0/1723.215.0.1 to 23.215.127.25423.215.127.25532,766
4823.215.128.0/1723.215.128.1 to 23.215.255.25423.215.255.25532,766
4923.216.0.0/1723.216.0.1 to 23.216.127.25423.216.127.25532,766
5023.216.128.0/1723.216.128.1 to 23.216.255.25423.216.255.25532,766
5123.217.0.0/1723.217.0.1 to 23.217.127.25423.217.127.25532,766
5223.217.128.0/1723.217.128.1 to 23.217.255.25423.217.255.25532,766
5323.218.0.0/1723.218.0.1 to 23.218.127.25423.218.127.25532,766
5423.218.128.0/1723.218.128.1 to 23.218.255.25423.218.255.25532,766
5523.219.0.0/1723.219.0.1 to 23.219.127.25423.219.127.25532,766
5623.219.128.0/1723.219.128.1 to 23.219.255.25423.219.255.25532,766
5723.220.0.0/1723.220.0.1 to 23.220.127.25423.220.127.25532,766
5823.220.128.0/1723.220.128.1 to 23.220.255.25423.220.255.25532,766
5923.221.0.0/1723.221.0.1 to 23.221.127.25423.221.127.25532,766
6023.221.128.0/1723.221.128.1 to 23.221.255.25423.221.255.25532,766
6123.222.0.0/1723.222.0.1 to 23.222.127.25423.222.127.25532,766
6223.222.128.0/1723.222.128.1 to 23.222.255.25423.222.255.25532,766
6323.223.0.0/1723.223.0.1 to 23.223.127.25423.223.127.25532,766
6423.223.128.0/1723.223.128.1 to 23.223.255.25423.223.255.25532,766

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.