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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.

Network1.239.96.0/19
Usable hosts8,190
Subnet mask255.255.224.0
Addresses8,192
Network address
1.239.96.0
Broadcast address
1.239.127.255
First usable
1.239.96.1
Last usable
1.239.127.254
Usable hosts
8,190 (8,192 less the network and broadcast addresses)
Subnet mask
255.255.224.0
Wildcard mask
0.0.31.255 (Cisco ACLs, OSPF)
Prefix length
/19
Type
Public public
Old class
A (default /8)
As numbers
Hex 01EF6000 · Integer 32464896 to 32473087
Reverse DNS zones
96.239.1.in-addr.arpa
97.239.1.in-addr.arpa
98.239.1.in-addr.arpa
99.239.1.in-addr.arpa
100.239.1.in-addr.arpa
101.239.1.in-addr.arpa
102.239.1.in-addr.arpa
103.239.1.in-addr.arpa
104.239.1.in-addr.arpa
105.239.1.in-addr.arpa
106.239.1.in-addr.arpa
107.239.1.in-addr.arpa
108.239.1.in-addr.arpa
109.239.1.in-addr.arpa
110.239.1.in-addr.arpa
111.239.1.in-addr.arpa
and 16 more
/19 is not on a 8-bit boundary, so it takes 32 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00000001.11101111.01100000.000000001.239.96.0
Subnet mask11111111.11111111.11100000.00000000255.255.224.0
Network00000001.11101111.01100000.000000001.239.96.0
Broadcast00000001.11101111.01111111.111111111.239.127.255
Split into smaller subnets/25
/20 (2)/21 (4)/22 (8)/23 (16)/24 (32)/25 (64)/26 (128)/27 (256)/28 (512)/29 (1,024)/30 (2,048)/31 (4,096)

1.239.96.0/19 makes 64 subnets of /25.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
11.239.96.0/251.239.96.1 to 1.239.96.1261.239.96.127126
21.239.96.128/251.239.96.129 to 1.239.96.2541.239.96.255126
31.239.97.0/251.239.97.1 to 1.239.97.1261.239.97.127126
41.239.97.128/251.239.97.129 to 1.239.97.2541.239.97.255126
51.239.98.0/251.239.98.1 to 1.239.98.1261.239.98.127126
61.239.98.128/251.239.98.129 to 1.239.98.2541.239.98.255126
71.239.99.0/251.239.99.1 to 1.239.99.1261.239.99.127126
81.239.99.128/251.239.99.129 to 1.239.99.2541.239.99.255126
91.239.100.0/251.239.100.1 to 1.239.100.1261.239.100.127126
101.239.100.128/251.239.100.129 to 1.239.100.2541.239.100.255126
111.239.101.0/251.239.101.1 to 1.239.101.1261.239.101.127126
121.239.101.128/251.239.101.129 to 1.239.101.2541.239.101.255126
131.239.102.0/251.239.102.1 to 1.239.102.1261.239.102.127126
141.239.102.128/251.239.102.129 to 1.239.102.2541.239.102.255126
151.239.103.0/251.239.103.1 to 1.239.103.1261.239.103.127126
161.239.103.128/251.239.103.129 to 1.239.103.2541.239.103.255126
171.239.104.0/251.239.104.1 to 1.239.104.1261.239.104.127126
181.239.104.128/251.239.104.129 to 1.239.104.2541.239.104.255126
191.239.105.0/251.239.105.1 to 1.239.105.1261.239.105.127126
201.239.105.128/251.239.105.129 to 1.239.105.2541.239.105.255126
211.239.106.0/251.239.106.1 to 1.239.106.1261.239.106.127126
221.239.106.128/251.239.106.129 to 1.239.106.2541.239.106.255126
231.239.107.0/251.239.107.1 to 1.239.107.1261.239.107.127126
241.239.107.128/251.239.107.129 to 1.239.107.2541.239.107.255126
251.239.108.0/251.239.108.1 to 1.239.108.1261.239.108.127126
261.239.108.128/251.239.108.129 to 1.239.108.2541.239.108.255126
271.239.109.0/251.239.109.1 to 1.239.109.1261.239.109.127126
281.239.109.128/251.239.109.129 to 1.239.109.2541.239.109.255126
291.239.110.0/251.239.110.1 to 1.239.110.1261.239.110.127126
301.239.110.128/251.239.110.129 to 1.239.110.2541.239.110.255126
311.239.111.0/251.239.111.1 to 1.239.111.1261.239.111.127126
321.239.111.128/251.239.111.129 to 1.239.111.2541.239.111.255126
331.239.112.0/251.239.112.1 to 1.239.112.1261.239.112.127126
341.239.112.128/251.239.112.129 to 1.239.112.2541.239.112.255126
351.239.113.0/251.239.113.1 to 1.239.113.1261.239.113.127126
361.239.113.128/251.239.113.129 to 1.239.113.2541.239.113.255126
371.239.114.0/251.239.114.1 to 1.239.114.1261.239.114.127126
381.239.114.128/251.239.114.129 to 1.239.114.2541.239.114.255126
391.239.115.0/251.239.115.1 to 1.239.115.1261.239.115.127126
401.239.115.128/251.239.115.129 to 1.239.115.2541.239.115.255126
411.239.116.0/251.239.116.1 to 1.239.116.1261.239.116.127126
421.239.116.128/251.239.116.129 to 1.239.116.2541.239.116.255126
431.239.117.0/251.239.117.1 to 1.239.117.1261.239.117.127126
441.239.117.128/251.239.117.129 to 1.239.117.2541.239.117.255126
451.239.118.0/251.239.118.1 to 1.239.118.1261.239.118.127126
461.239.118.128/251.239.118.129 to 1.239.118.2541.239.118.255126
471.239.119.0/251.239.119.1 to 1.239.119.1261.239.119.127126
481.239.119.128/251.239.119.129 to 1.239.119.2541.239.119.255126
491.239.120.0/251.239.120.1 to 1.239.120.1261.239.120.127126
501.239.120.128/251.239.120.129 to 1.239.120.2541.239.120.255126
511.239.121.0/251.239.121.1 to 1.239.121.1261.239.121.127126
521.239.121.128/251.239.121.129 to 1.239.121.2541.239.121.255126
531.239.122.0/251.239.122.1 to 1.239.122.1261.239.122.127126
541.239.122.128/251.239.122.129 to 1.239.122.2541.239.122.255126
551.239.123.0/251.239.123.1 to 1.239.123.1261.239.123.127126
561.239.123.128/251.239.123.129 to 1.239.123.2541.239.123.255126
571.239.124.0/251.239.124.1 to 1.239.124.1261.239.124.127126
581.239.124.128/251.239.124.129 to 1.239.124.2541.239.124.255126
591.239.125.0/251.239.125.1 to 1.239.125.1261.239.125.127126
601.239.125.128/251.239.125.129 to 1.239.125.2541.239.125.255126
611.239.126.0/251.239.126.1 to 1.239.126.1261.239.126.127126
621.239.126.128/251.239.126.129 to 1.239.126.2541.239.126.255126
631.239.127.0/251.239.127.1 to 1.239.127.1261.239.127.127126
641.239.127.128/251.239.127.129 to 1.239.127.2541.239.127.255126

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.