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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.

Network20.232.32.0/19
Usable hosts8,190
Subnet mask255.255.224.0
Addresses8,192
Network address
20.232.32.0
Broadcast address
20.232.63.255
First usable
20.232.32.1
Last usable
20.232.63.254
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 14E82000 · Integer 350756864 to 350765055
Reverse DNS zones
32.232.20.in-addr.arpa
33.232.20.in-addr.arpa
34.232.20.in-addr.arpa
35.232.20.in-addr.arpa
36.232.20.in-addr.arpa
37.232.20.in-addr.arpa
38.232.20.in-addr.arpa
39.232.20.in-addr.arpa
40.232.20.in-addr.arpa
41.232.20.in-addr.arpa
42.232.20.in-addr.arpa
43.232.20.in-addr.arpa
44.232.20.in-addr.arpa
45.232.20.in-addr.arpa
46.232.20.in-addr.arpa
47.232.20.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
Address00010100.11101000.00100000.0000000020.232.32.0
Subnet mask11111111.11111111.11100000.00000000255.255.224.0
Network00010100.11101000.00100000.0000000020.232.32.0
Broadcast00010100.11101000.00111111.1111111120.232.63.255
Split into smaller subnets/26
/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)

20.232.32.0/19 makes 128 subnets of /26.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
120.232.32.0/2620.232.32.1 to 20.232.32.6220.232.32.6362
220.232.32.64/2620.232.32.65 to 20.232.32.12620.232.32.12762
320.232.32.128/2620.232.32.129 to 20.232.32.19020.232.32.19162
420.232.32.192/2620.232.32.193 to 20.232.32.25420.232.32.25562
520.232.33.0/2620.232.33.1 to 20.232.33.6220.232.33.6362
620.232.33.64/2620.232.33.65 to 20.232.33.12620.232.33.12762
720.232.33.128/2620.232.33.129 to 20.232.33.19020.232.33.19162
820.232.33.192/2620.232.33.193 to 20.232.33.25420.232.33.25562
920.232.34.0/2620.232.34.1 to 20.232.34.6220.232.34.6362
1020.232.34.64/2620.232.34.65 to 20.232.34.12620.232.34.12762
1120.232.34.128/2620.232.34.129 to 20.232.34.19020.232.34.19162
1220.232.34.192/2620.232.34.193 to 20.232.34.25420.232.34.25562
1320.232.35.0/2620.232.35.1 to 20.232.35.6220.232.35.6362
1420.232.35.64/2620.232.35.65 to 20.232.35.12620.232.35.12762
1520.232.35.128/2620.232.35.129 to 20.232.35.19020.232.35.19162
1620.232.35.192/2620.232.35.193 to 20.232.35.25420.232.35.25562
1720.232.36.0/2620.232.36.1 to 20.232.36.6220.232.36.6362
1820.232.36.64/2620.232.36.65 to 20.232.36.12620.232.36.12762
1920.232.36.128/2620.232.36.129 to 20.232.36.19020.232.36.19162
2020.232.36.192/2620.232.36.193 to 20.232.36.25420.232.36.25562
2120.232.37.0/2620.232.37.1 to 20.232.37.6220.232.37.6362
2220.232.37.64/2620.232.37.65 to 20.232.37.12620.232.37.12762
2320.232.37.128/2620.232.37.129 to 20.232.37.19020.232.37.19162
2420.232.37.192/2620.232.37.193 to 20.232.37.25420.232.37.25562
2520.232.38.0/2620.232.38.1 to 20.232.38.6220.232.38.6362
2620.232.38.64/2620.232.38.65 to 20.232.38.12620.232.38.12762
2720.232.38.128/2620.232.38.129 to 20.232.38.19020.232.38.19162
2820.232.38.192/2620.232.38.193 to 20.232.38.25420.232.38.25562
2920.232.39.0/2620.232.39.1 to 20.232.39.6220.232.39.6362
3020.232.39.64/2620.232.39.65 to 20.232.39.12620.232.39.12762
3120.232.39.128/2620.232.39.129 to 20.232.39.19020.232.39.19162
3220.232.39.192/2620.232.39.193 to 20.232.39.25420.232.39.25562
3320.232.40.0/2620.232.40.1 to 20.232.40.6220.232.40.6362
3420.232.40.64/2620.232.40.65 to 20.232.40.12620.232.40.12762
3520.232.40.128/2620.232.40.129 to 20.232.40.19020.232.40.19162
3620.232.40.192/2620.232.40.193 to 20.232.40.25420.232.40.25562
3720.232.41.0/2620.232.41.1 to 20.232.41.6220.232.41.6362
3820.232.41.64/2620.232.41.65 to 20.232.41.12620.232.41.12762
3920.232.41.128/2620.232.41.129 to 20.232.41.19020.232.41.19162
4020.232.41.192/2620.232.41.193 to 20.232.41.25420.232.41.25562
4120.232.42.0/2620.232.42.1 to 20.232.42.6220.232.42.6362
4220.232.42.64/2620.232.42.65 to 20.232.42.12620.232.42.12762
4320.232.42.128/2620.232.42.129 to 20.232.42.19020.232.42.19162
4420.232.42.192/2620.232.42.193 to 20.232.42.25420.232.42.25562
4520.232.43.0/2620.232.43.1 to 20.232.43.6220.232.43.6362
4620.232.43.64/2620.232.43.65 to 20.232.43.12620.232.43.12762
4720.232.43.128/2620.232.43.129 to 20.232.43.19020.232.43.19162
4820.232.43.192/2620.232.43.193 to 20.232.43.25420.232.43.25562
4920.232.44.0/2620.232.44.1 to 20.232.44.6220.232.44.6362
5020.232.44.64/2620.232.44.65 to 20.232.44.12620.232.44.12762
5120.232.44.128/2620.232.44.129 to 20.232.44.19020.232.44.19162
5220.232.44.192/2620.232.44.193 to 20.232.44.25420.232.44.25562
5320.232.45.0/2620.232.45.1 to 20.232.45.6220.232.45.6362
5420.232.45.64/2620.232.45.65 to 20.232.45.12620.232.45.12762
5520.232.45.128/2620.232.45.129 to 20.232.45.19020.232.45.19162
5620.232.45.192/2620.232.45.193 to 20.232.45.25420.232.45.25562
5720.232.46.0/2620.232.46.1 to 20.232.46.6220.232.46.6362
5820.232.46.64/2620.232.46.65 to 20.232.46.12620.232.46.12762
5920.232.46.128/2620.232.46.129 to 20.232.46.19020.232.46.19162
6020.232.46.192/2620.232.46.193 to 20.232.46.25420.232.46.25562
6120.232.47.0/2620.232.47.1 to 20.232.47.6220.232.47.6362
6220.232.47.64/2620.232.47.65 to 20.232.47.12620.232.47.12762
6320.232.47.128/2620.232.47.129 to 20.232.47.19020.232.47.19162
6420.232.47.192/2620.232.47.193 to 20.232.47.25420.232.47.25562
6520.232.48.0/2620.232.48.1 to 20.232.48.6220.232.48.6362
6620.232.48.64/2620.232.48.65 to 20.232.48.12620.232.48.12762
6720.232.48.128/2620.232.48.129 to 20.232.48.19020.232.48.19162
6820.232.48.192/2620.232.48.193 to 20.232.48.25420.232.48.25562
6920.232.49.0/2620.232.49.1 to 20.232.49.6220.232.49.6362
7020.232.49.64/2620.232.49.65 to 20.232.49.12620.232.49.12762
7120.232.49.128/2620.232.49.129 to 20.232.49.19020.232.49.19162
7220.232.49.192/2620.232.49.193 to 20.232.49.25420.232.49.25562
7320.232.50.0/2620.232.50.1 to 20.232.50.6220.232.50.6362
7420.232.50.64/2620.232.50.65 to 20.232.50.12620.232.50.12762
7520.232.50.128/2620.232.50.129 to 20.232.50.19020.232.50.19162
7620.232.50.192/2620.232.50.193 to 20.232.50.25420.232.50.25562
7720.232.51.0/2620.232.51.1 to 20.232.51.6220.232.51.6362
7820.232.51.64/2620.232.51.65 to 20.232.51.12620.232.51.12762
7920.232.51.128/2620.232.51.129 to 20.232.51.19020.232.51.19162
8020.232.51.192/2620.232.51.193 to 20.232.51.25420.232.51.25562
8120.232.52.0/2620.232.52.1 to 20.232.52.6220.232.52.6362
8220.232.52.64/2620.232.52.65 to 20.232.52.12620.232.52.12762
8320.232.52.128/2620.232.52.129 to 20.232.52.19020.232.52.19162
8420.232.52.192/2620.232.52.193 to 20.232.52.25420.232.52.25562
8520.232.53.0/2620.232.53.1 to 20.232.53.6220.232.53.6362
8620.232.53.64/2620.232.53.65 to 20.232.53.12620.232.53.12762
8720.232.53.128/2620.232.53.129 to 20.232.53.19020.232.53.19162
8820.232.53.192/2620.232.53.193 to 20.232.53.25420.232.53.25562
8920.232.54.0/2620.232.54.1 to 20.232.54.6220.232.54.6362
9020.232.54.64/2620.232.54.65 to 20.232.54.12620.232.54.12762
9120.232.54.128/2620.232.54.129 to 20.232.54.19020.232.54.19162
9220.232.54.192/2620.232.54.193 to 20.232.54.25420.232.54.25562
9320.232.55.0/2620.232.55.1 to 20.232.55.6220.232.55.6362
9420.232.55.64/2620.232.55.65 to 20.232.55.12620.232.55.12762
9520.232.55.128/2620.232.55.129 to 20.232.55.19020.232.55.19162
9620.232.55.192/2620.232.55.193 to 20.232.55.25420.232.55.25562
9720.232.56.0/2620.232.56.1 to 20.232.56.6220.232.56.6362
9820.232.56.64/2620.232.56.65 to 20.232.56.12620.232.56.12762
9920.232.56.128/2620.232.56.129 to 20.232.56.19020.232.56.19162
10020.232.56.192/2620.232.56.193 to 20.232.56.25420.232.56.25562
10120.232.57.0/2620.232.57.1 to 20.232.57.6220.232.57.6362
10220.232.57.64/2620.232.57.65 to 20.232.57.12620.232.57.12762
10320.232.57.128/2620.232.57.129 to 20.232.57.19020.232.57.19162
10420.232.57.192/2620.232.57.193 to 20.232.57.25420.232.57.25562
10520.232.58.0/2620.232.58.1 to 20.232.58.6220.232.58.6362
10620.232.58.64/2620.232.58.65 to 20.232.58.12620.232.58.12762
10720.232.58.128/2620.232.58.129 to 20.232.58.19020.232.58.19162
10820.232.58.192/2620.232.58.193 to 20.232.58.25420.232.58.25562
10920.232.59.0/2620.232.59.1 to 20.232.59.6220.232.59.6362
11020.232.59.64/2620.232.59.65 to 20.232.59.12620.232.59.12762
11120.232.59.128/2620.232.59.129 to 20.232.59.19020.232.59.19162
11220.232.59.192/2620.232.59.193 to 20.232.59.25420.232.59.25562
11320.232.60.0/2620.232.60.1 to 20.232.60.6220.232.60.6362
11420.232.60.64/2620.232.60.65 to 20.232.60.12620.232.60.12762
11520.232.60.128/2620.232.60.129 to 20.232.60.19020.232.60.19162
11620.232.60.192/2620.232.60.193 to 20.232.60.25420.232.60.25562
11720.232.61.0/2620.232.61.1 to 20.232.61.6220.232.61.6362
11820.232.61.64/2620.232.61.65 to 20.232.61.12620.232.61.12762
11920.232.61.128/2620.232.61.129 to 20.232.61.19020.232.61.19162
12020.232.61.192/2620.232.61.193 to 20.232.61.25420.232.61.25562
12120.232.62.0/2620.232.62.1 to 20.232.62.6220.232.62.6362
12220.232.62.64/2620.232.62.65 to 20.232.62.12620.232.62.12762
12320.232.62.128/2620.232.62.129 to 20.232.62.19020.232.62.19162
12420.232.62.192/2620.232.62.193 to 20.232.62.25420.232.62.25562
12520.232.63.0/2620.232.63.1 to 20.232.63.6220.232.63.6362
12620.232.63.64/2620.232.63.65 to 20.232.63.12620.232.63.12762
12720.232.63.128/2620.232.63.129 to 20.232.63.19020.232.63.19162
12820.232.63.192/2620.232.63.193 to 20.232.63.25420.232.63.25562

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.