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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.

Network124.2.32.0/19
Usable hosts8,190
Subnet mask255.255.224.0
Addresses8,192
Network address
124.2.32.0
Broadcast address
124.2.63.255
First usable
124.2.32.1
Last usable
124.2.63.254
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 7C022000 · Integer 2080514048 to 2080522239
Reverse DNS zones
32.2.124.in-addr.arpa
33.2.124.in-addr.arpa
34.2.124.in-addr.arpa
35.2.124.in-addr.arpa
36.2.124.in-addr.arpa
37.2.124.in-addr.arpa
38.2.124.in-addr.arpa
39.2.124.in-addr.arpa
40.2.124.in-addr.arpa
41.2.124.in-addr.arpa
42.2.124.in-addr.arpa
43.2.124.in-addr.arpa
44.2.124.in-addr.arpa
45.2.124.in-addr.arpa
46.2.124.in-addr.arpa
47.2.124.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
Address01111100.00000010.00100000.00000000124.2.32.0
Subnet mask11111111.11111111.11100000.00000000255.255.224.0
Network01111100.00000010.00100000.00000000124.2.32.0
Broadcast01111100.00000010.00111111.11111111124.2.63.255
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)

124.2.32.0/19 makes 128 subnets of /26.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1124.2.32.0/26124.2.32.1 to 124.2.32.62124.2.32.6362
2124.2.32.64/26124.2.32.65 to 124.2.32.126124.2.32.12762
3124.2.32.128/26124.2.32.129 to 124.2.32.190124.2.32.19162
4124.2.32.192/26124.2.32.193 to 124.2.32.254124.2.32.25562
5124.2.33.0/26124.2.33.1 to 124.2.33.62124.2.33.6362
6124.2.33.64/26124.2.33.65 to 124.2.33.126124.2.33.12762
7124.2.33.128/26124.2.33.129 to 124.2.33.190124.2.33.19162
8124.2.33.192/26124.2.33.193 to 124.2.33.254124.2.33.25562
9124.2.34.0/26124.2.34.1 to 124.2.34.62124.2.34.6362
10124.2.34.64/26124.2.34.65 to 124.2.34.126124.2.34.12762
11124.2.34.128/26124.2.34.129 to 124.2.34.190124.2.34.19162
12124.2.34.192/26124.2.34.193 to 124.2.34.254124.2.34.25562
13124.2.35.0/26124.2.35.1 to 124.2.35.62124.2.35.6362
14124.2.35.64/26124.2.35.65 to 124.2.35.126124.2.35.12762
15124.2.35.128/26124.2.35.129 to 124.2.35.190124.2.35.19162
16124.2.35.192/26124.2.35.193 to 124.2.35.254124.2.35.25562
17124.2.36.0/26124.2.36.1 to 124.2.36.62124.2.36.6362
18124.2.36.64/26124.2.36.65 to 124.2.36.126124.2.36.12762
19124.2.36.128/26124.2.36.129 to 124.2.36.190124.2.36.19162
20124.2.36.192/26124.2.36.193 to 124.2.36.254124.2.36.25562
21124.2.37.0/26124.2.37.1 to 124.2.37.62124.2.37.6362
22124.2.37.64/26124.2.37.65 to 124.2.37.126124.2.37.12762
23124.2.37.128/26124.2.37.129 to 124.2.37.190124.2.37.19162
24124.2.37.192/26124.2.37.193 to 124.2.37.254124.2.37.25562
25124.2.38.0/26124.2.38.1 to 124.2.38.62124.2.38.6362
26124.2.38.64/26124.2.38.65 to 124.2.38.126124.2.38.12762
27124.2.38.128/26124.2.38.129 to 124.2.38.190124.2.38.19162
28124.2.38.192/26124.2.38.193 to 124.2.38.254124.2.38.25562
29124.2.39.0/26124.2.39.1 to 124.2.39.62124.2.39.6362
30124.2.39.64/26124.2.39.65 to 124.2.39.126124.2.39.12762
31124.2.39.128/26124.2.39.129 to 124.2.39.190124.2.39.19162
32124.2.39.192/26124.2.39.193 to 124.2.39.254124.2.39.25562
33124.2.40.0/26124.2.40.1 to 124.2.40.62124.2.40.6362
34124.2.40.64/26124.2.40.65 to 124.2.40.126124.2.40.12762
35124.2.40.128/26124.2.40.129 to 124.2.40.190124.2.40.19162
36124.2.40.192/26124.2.40.193 to 124.2.40.254124.2.40.25562
37124.2.41.0/26124.2.41.1 to 124.2.41.62124.2.41.6362
38124.2.41.64/26124.2.41.65 to 124.2.41.126124.2.41.12762
39124.2.41.128/26124.2.41.129 to 124.2.41.190124.2.41.19162
40124.2.41.192/26124.2.41.193 to 124.2.41.254124.2.41.25562
41124.2.42.0/26124.2.42.1 to 124.2.42.62124.2.42.6362
42124.2.42.64/26124.2.42.65 to 124.2.42.126124.2.42.12762
43124.2.42.128/26124.2.42.129 to 124.2.42.190124.2.42.19162
44124.2.42.192/26124.2.42.193 to 124.2.42.254124.2.42.25562
45124.2.43.0/26124.2.43.1 to 124.2.43.62124.2.43.6362
46124.2.43.64/26124.2.43.65 to 124.2.43.126124.2.43.12762
47124.2.43.128/26124.2.43.129 to 124.2.43.190124.2.43.19162
48124.2.43.192/26124.2.43.193 to 124.2.43.254124.2.43.25562
49124.2.44.0/26124.2.44.1 to 124.2.44.62124.2.44.6362
50124.2.44.64/26124.2.44.65 to 124.2.44.126124.2.44.12762
51124.2.44.128/26124.2.44.129 to 124.2.44.190124.2.44.19162
52124.2.44.192/26124.2.44.193 to 124.2.44.254124.2.44.25562
53124.2.45.0/26124.2.45.1 to 124.2.45.62124.2.45.6362
54124.2.45.64/26124.2.45.65 to 124.2.45.126124.2.45.12762
55124.2.45.128/26124.2.45.129 to 124.2.45.190124.2.45.19162
56124.2.45.192/26124.2.45.193 to 124.2.45.254124.2.45.25562
57124.2.46.0/26124.2.46.1 to 124.2.46.62124.2.46.6362
58124.2.46.64/26124.2.46.65 to 124.2.46.126124.2.46.12762
59124.2.46.128/26124.2.46.129 to 124.2.46.190124.2.46.19162
60124.2.46.192/26124.2.46.193 to 124.2.46.254124.2.46.25562
61124.2.47.0/26124.2.47.1 to 124.2.47.62124.2.47.6362
62124.2.47.64/26124.2.47.65 to 124.2.47.126124.2.47.12762
63124.2.47.128/26124.2.47.129 to 124.2.47.190124.2.47.19162
64124.2.47.192/26124.2.47.193 to 124.2.47.254124.2.47.25562
65124.2.48.0/26124.2.48.1 to 124.2.48.62124.2.48.6362
66124.2.48.64/26124.2.48.65 to 124.2.48.126124.2.48.12762
67124.2.48.128/26124.2.48.129 to 124.2.48.190124.2.48.19162
68124.2.48.192/26124.2.48.193 to 124.2.48.254124.2.48.25562
69124.2.49.0/26124.2.49.1 to 124.2.49.62124.2.49.6362
70124.2.49.64/26124.2.49.65 to 124.2.49.126124.2.49.12762
71124.2.49.128/26124.2.49.129 to 124.2.49.190124.2.49.19162
72124.2.49.192/26124.2.49.193 to 124.2.49.254124.2.49.25562
73124.2.50.0/26124.2.50.1 to 124.2.50.62124.2.50.6362
74124.2.50.64/26124.2.50.65 to 124.2.50.126124.2.50.12762
75124.2.50.128/26124.2.50.129 to 124.2.50.190124.2.50.19162
76124.2.50.192/26124.2.50.193 to 124.2.50.254124.2.50.25562
77124.2.51.0/26124.2.51.1 to 124.2.51.62124.2.51.6362
78124.2.51.64/26124.2.51.65 to 124.2.51.126124.2.51.12762
79124.2.51.128/26124.2.51.129 to 124.2.51.190124.2.51.19162
80124.2.51.192/26124.2.51.193 to 124.2.51.254124.2.51.25562
81124.2.52.0/26124.2.52.1 to 124.2.52.62124.2.52.6362
82124.2.52.64/26124.2.52.65 to 124.2.52.126124.2.52.12762
83124.2.52.128/26124.2.52.129 to 124.2.52.190124.2.52.19162
84124.2.52.192/26124.2.52.193 to 124.2.52.254124.2.52.25562
85124.2.53.0/26124.2.53.1 to 124.2.53.62124.2.53.6362
86124.2.53.64/26124.2.53.65 to 124.2.53.126124.2.53.12762
87124.2.53.128/26124.2.53.129 to 124.2.53.190124.2.53.19162
88124.2.53.192/26124.2.53.193 to 124.2.53.254124.2.53.25562
89124.2.54.0/26124.2.54.1 to 124.2.54.62124.2.54.6362
90124.2.54.64/26124.2.54.65 to 124.2.54.126124.2.54.12762
91124.2.54.128/26124.2.54.129 to 124.2.54.190124.2.54.19162
92124.2.54.192/26124.2.54.193 to 124.2.54.254124.2.54.25562
93124.2.55.0/26124.2.55.1 to 124.2.55.62124.2.55.6362
94124.2.55.64/26124.2.55.65 to 124.2.55.126124.2.55.12762
95124.2.55.128/26124.2.55.129 to 124.2.55.190124.2.55.19162
96124.2.55.192/26124.2.55.193 to 124.2.55.254124.2.55.25562
97124.2.56.0/26124.2.56.1 to 124.2.56.62124.2.56.6362
98124.2.56.64/26124.2.56.65 to 124.2.56.126124.2.56.12762
99124.2.56.128/26124.2.56.129 to 124.2.56.190124.2.56.19162
100124.2.56.192/26124.2.56.193 to 124.2.56.254124.2.56.25562
101124.2.57.0/26124.2.57.1 to 124.2.57.62124.2.57.6362
102124.2.57.64/26124.2.57.65 to 124.2.57.126124.2.57.12762
103124.2.57.128/26124.2.57.129 to 124.2.57.190124.2.57.19162
104124.2.57.192/26124.2.57.193 to 124.2.57.254124.2.57.25562
105124.2.58.0/26124.2.58.1 to 124.2.58.62124.2.58.6362
106124.2.58.64/26124.2.58.65 to 124.2.58.126124.2.58.12762
107124.2.58.128/26124.2.58.129 to 124.2.58.190124.2.58.19162
108124.2.58.192/26124.2.58.193 to 124.2.58.254124.2.58.25562
109124.2.59.0/26124.2.59.1 to 124.2.59.62124.2.59.6362
110124.2.59.64/26124.2.59.65 to 124.2.59.126124.2.59.12762
111124.2.59.128/26124.2.59.129 to 124.2.59.190124.2.59.19162
112124.2.59.192/26124.2.59.193 to 124.2.59.254124.2.59.25562
113124.2.60.0/26124.2.60.1 to 124.2.60.62124.2.60.6362
114124.2.60.64/26124.2.60.65 to 124.2.60.126124.2.60.12762
115124.2.60.128/26124.2.60.129 to 124.2.60.190124.2.60.19162
116124.2.60.192/26124.2.60.193 to 124.2.60.254124.2.60.25562
117124.2.61.0/26124.2.61.1 to 124.2.61.62124.2.61.6362
118124.2.61.64/26124.2.61.65 to 124.2.61.126124.2.61.12762
119124.2.61.128/26124.2.61.129 to 124.2.61.190124.2.61.19162
120124.2.61.192/26124.2.61.193 to 124.2.61.254124.2.61.25562
121124.2.62.0/26124.2.62.1 to 124.2.62.62124.2.62.6362
122124.2.62.64/26124.2.62.65 to 124.2.62.126124.2.62.12762
123124.2.62.128/26124.2.62.129 to 124.2.62.190124.2.62.19162
124124.2.62.192/26124.2.62.193 to 124.2.62.254124.2.62.25562
125124.2.63.0/26124.2.63.1 to 124.2.63.62124.2.63.6362
126124.2.63.64/26124.2.63.65 to 124.2.63.126124.2.63.12762
127124.2.63.128/26124.2.63.129 to 124.2.63.190124.2.63.19162
128124.2.63.192/26124.2.63.193 to 124.2.63.254124.2.63.25562

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.