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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.

Network225.128.0.0/11
Usable hosts2,097,150
Subnet mask255.224.0.0
Addresses2,097,152
Network address
225.128.0.0
Broadcast address
225.159.255.255
First usable
225.128.0.1
Last usable
225.159.255.254
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
Multicast 224.0.0.0/4
One-to-many traffic, such as IPTV and routing protocols
Old class
D (multicast)
As numbers
Hex E1800000 · Integer 3783262208 to 3785359359
Reverse DNS zones
128.225.in-addr.arpa
129.225.in-addr.arpa
130.225.in-addr.arpa
131.225.in-addr.arpa
132.225.in-addr.arpa
133.225.in-addr.arpa
134.225.in-addr.arpa
135.225.in-addr.arpa
136.225.in-addr.arpa
137.225.in-addr.arpa
138.225.in-addr.arpa
139.225.in-addr.arpa
140.225.in-addr.arpa
141.225.in-addr.arpa
142.225.in-addr.arpa
143.225.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
Address11100001.10000000.00000000.00000000225.128.0.0
Subnet mask11111111.11100000.00000000.00000000255.224.0.0
Network11100001.10000000.00000000.00000000225.128.0.0
Broadcast11100001.10011111.11111111.11111111225.159.255.255
Split into smaller subnets/18
/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)

225.128.0.0/11 makes 128 subnets of /18.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1225.128.0.0/18225.128.0.1 to 225.128.63.254225.128.63.25516,382
2225.128.64.0/18225.128.64.1 to 225.128.127.254225.128.127.25516,382
3225.128.128.0/18225.128.128.1 to 225.128.191.254225.128.191.25516,382
4225.128.192.0/18225.128.192.1 to 225.128.255.254225.128.255.25516,382
5225.129.0.0/18225.129.0.1 to 225.129.63.254225.129.63.25516,382
6225.129.64.0/18225.129.64.1 to 225.129.127.254225.129.127.25516,382
7225.129.128.0/18225.129.128.1 to 225.129.191.254225.129.191.25516,382
8225.129.192.0/18225.129.192.1 to 225.129.255.254225.129.255.25516,382
9225.130.0.0/18225.130.0.1 to 225.130.63.254225.130.63.25516,382
10225.130.64.0/18225.130.64.1 to 225.130.127.254225.130.127.25516,382
11225.130.128.0/18225.130.128.1 to 225.130.191.254225.130.191.25516,382
12225.130.192.0/18225.130.192.1 to 225.130.255.254225.130.255.25516,382
13225.131.0.0/18225.131.0.1 to 225.131.63.254225.131.63.25516,382
14225.131.64.0/18225.131.64.1 to 225.131.127.254225.131.127.25516,382
15225.131.128.0/18225.131.128.1 to 225.131.191.254225.131.191.25516,382
16225.131.192.0/18225.131.192.1 to 225.131.255.254225.131.255.25516,382
17225.132.0.0/18225.132.0.1 to 225.132.63.254225.132.63.25516,382
18225.132.64.0/18225.132.64.1 to 225.132.127.254225.132.127.25516,382
19225.132.128.0/18225.132.128.1 to 225.132.191.254225.132.191.25516,382
20225.132.192.0/18225.132.192.1 to 225.132.255.254225.132.255.25516,382
21225.133.0.0/18225.133.0.1 to 225.133.63.254225.133.63.25516,382
22225.133.64.0/18225.133.64.1 to 225.133.127.254225.133.127.25516,382
23225.133.128.0/18225.133.128.1 to 225.133.191.254225.133.191.25516,382
24225.133.192.0/18225.133.192.1 to 225.133.255.254225.133.255.25516,382
25225.134.0.0/18225.134.0.1 to 225.134.63.254225.134.63.25516,382
26225.134.64.0/18225.134.64.1 to 225.134.127.254225.134.127.25516,382
27225.134.128.0/18225.134.128.1 to 225.134.191.254225.134.191.25516,382
28225.134.192.0/18225.134.192.1 to 225.134.255.254225.134.255.25516,382
29225.135.0.0/18225.135.0.1 to 225.135.63.254225.135.63.25516,382
30225.135.64.0/18225.135.64.1 to 225.135.127.254225.135.127.25516,382
31225.135.128.0/18225.135.128.1 to 225.135.191.254225.135.191.25516,382
32225.135.192.0/18225.135.192.1 to 225.135.255.254225.135.255.25516,382
33225.136.0.0/18225.136.0.1 to 225.136.63.254225.136.63.25516,382
34225.136.64.0/18225.136.64.1 to 225.136.127.254225.136.127.25516,382
35225.136.128.0/18225.136.128.1 to 225.136.191.254225.136.191.25516,382
36225.136.192.0/18225.136.192.1 to 225.136.255.254225.136.255.25516,382
37225.137.0.0/18225.137.0.1 to 225.137.63.254225.137.63.25516,382
38225.137.64.0/18225.137.64.1 to 225.137.127.254225.137.127.25516,382
39225.137.128.0/18225.137.128.1 to 225.137.191.254225.137.191.25516,382
40225.137.192.0/18225.137.192.1 to 225.137.255.254225.137.255.25516,382
41225.138.0.0/18225.138.0.1 to 225.138.63.254225.138.63.25516,382
42225.138.64.0/18225.138.64.1 to 225.138.127.254225.138.127.25516,382
43225.138.128.0/18225.138.128.1 to 225.138.191.254225.138.191.25516,382
44225.138.192.0/18225.138.192.1 to 225.138.255.254225.138.255.25516,382
45225.139.0.0/18225.139.0.1 to 225.139.63.254225.139.63.25516,382
46225.139.64.0/18225.139.64.1 to 225.139.127.254225.139.127.25516,382
47225.139.128.0/18225.139.128.1 to 225.139.191.254225.139.191.25516,382
48225.139.192.0/18225.139.192.1 to 225.139.255.254225.139.255.25516,382
49225.140.0.0/18225.140.0.1 to 225.140.63.254225.140.63.25516,382
50225.140.64.0/18225.140.64.1 to 225.140.127.254225.140.127.25516,382
51225.140.128.0/18225.140.128.1 to 225.140.191.254225.140.191.25516,382
52225.140.192.0/18225.140.192.1 to 225.140.255.254225.140.255.25516,382
53225.141.0.0/18225.141.0.1 to 225.141.63.254225.141.63.25516,382
54225.141.64.0/18225.141.64.1 to 225.141.127.254225.141.127.25516,382
55225.141.128.0/18225.141.128.1 to 225.141.191.254225.141.191.25516,382
56225.141.192.0/18225.141.192.1 to 225.141.255.254225.141.255.25516,382
57225.142.0.0/18225.142.0.1 to 225.142.63.254225.142.63.25516,382
58225.142.64.0/18225.142.64.1 to 225.142.127.254225.142.127.25516,382
59225.142.128.0/18225.142.128.1 to 225.142.191.254225.142.191.25516,382
60225.142.192.0/18225.142.192.1 to 225.142.255.254225.142.255.25516,382
61225.143.0.0/18225.143.0.1 to 225.143.63.254225.143.63.25516,382
62225.143.64.0/18225.143.64.1 to 225.143.127.254225.143.127.25516,382
63225.143.128.0/18225.143.128.1 to 225.143.191.254225.143.191.25516,382
64225.143.192.0/18225.143.192.1 to 225.143.255.254225.143.255.25516,382
65225.144.0.0/18225.144.0.1 to 225.144.63.254225.144.63.25516,382
66225.144.64.0/18225.144.64.1 to 225.144.127.254225.144.127.25516,382
67225.144.128.0/18225.144.128.1 to 225.144.191.254225.144.191.25516,382
68225.144.192.0/18225.144.192.1 to 225.144.255.254225.144.255.25516,382
69225.145.0.0/18225.145.0.1 to 225.145.63.254225.145.63.25516,382
70225.145.64.0/18225.145.64.1 to 225.145.127.254225.145.127.25516,382
71225.145.128.0/18225.145.128.1 to 225.145.191.254225.145.191.25516,382
72225.145.192.0/18225.145.192.1 to 225.145.255.254225.145.255.25516,382
73225.146.0.0/18225.146.0.1 to 225.146.63.254225.146.63.25516,382
74225.146.64.0/18225.146.64.1 to 225.146.127.254225.146.127.25516,382
75225.146.128.0/18225.146.128.1 to 225.146.191.254225.146.191.25516,382
76225.146.192.0/18225.146.192.1 to 225.146.255.254225.146.255.25516,382
77225.147.0.0/18225.147.0.1 to 225.147.63.254225.147.63.25516,382
78225.147.64.0/18225.147.64.1 to 225.147.127.254225.147.127.25516,382
79225.147.128.0/18225.147.128.1 to 225.147.191.254225.147.191.25516,382
80225.147.192.0/18225.147.192.1 to 225.147.255.254225.147.255.25516,382
81225.148.0.0/18225.148.0.1 to 225.148.63.254225.148.63.25516,382
82225.148.64.0/18225.148.64.1 to 225.148.127.254225.148.127.25516,382
83225.148.128.0/18225.148.128.1 to 225.148.191.254225.148.191.25516,382
84225.148.192.0/18225.148.192.1 to 225.148.255.254225.148.255.25516,382
85225.149.0.0/18225.149.0.1 to 225.149.63.254225.149.63.25516,382
86225.149.64.0/18225.149.64.1 to 225.149.127.254225.149.127.25516,382
87225.149.128.0/18225.149.128.1 to 225.149.191.254225.149.191.25516,382
88225.149.192.0/18225.149.192.1 to 225.149.255.254225.149.255.25516,382
89225.150.0.0/18225.150.0.1 to 225.150.63.254225.150.63.25516,382
90225.150.64.0/18225.150.64.1 to 225.150.127.254225.150.127.25516,382
91225.150.128.0/18225.150.128.1 to 225.150.191.254225.150.191.25516,382
92225.150.192.0/18225.150.192.1 to 225.150.255.254225.150.255.25516,382
93225.151.0.0/18225.151.0.1 to 225.151.63.254225.151.63.25516,382
94225.151.64.0/18225.151.64.1 to 225.151.127.254225.151.127.25516,382
95225.151.128.0/18225.151.128.1 to 225.151.191.254225.151.191.25516,382
96225.151.192.0/18225.151.192.1 to 225.151.255.254225.151.255.25516,382
97225.152.0.0/18225.152.0.1 to 225.152.63.254225.152.63.25516,382
98225.152.64.0/18225.152.64.1 to 225.152.127.254225.152.127.25516,382
99225.152.128.0/18225.152.128.1 to 225.152.191.254225.152.191.25516,382
100225.152.192.0/18225.152.192.1 to 225.152.255.254225.152.255.25516,382
101225.153.0.0/18225.153.0.1 to 225.153.63.254225.153.63.25516,382
102225.153.64.0/18225.153.64.1 to 225.153.127.254225.153.127.25516,382
103225.153.128.0/18225.153.128.1 to 225.153.191.254225.153.191.25516,382
104225.153.192.0/18225.153.192.1 to 225.153.255.254225.153.255.25516,382
105225.154.0.0/18225.154.0.1 to 225.154.63.254225.154.63.25516,382
106225.154.64.0/18225.154.64.1 to 225.154.127.254225.154.127.25516,382
107225.154.128.0/18225.154.128.1 to 225.154.191.254225.154.191.25516,382
108225.154.192.0/18225.154.192.1 to 225.154.255.254225.154.255.25516,382
109225.155.0.0/18225.155.0.1 to 225.155.63.254225.155.63.25516,382
110225.155.64.0/18225.155.64.1 to 225.155.127.254225.155.127.25516,382
111225.155.128.0/18225.155.128.1 to 225.155.191.254225.155.191.25516,382
112225.155.192.0/18225.155.192.1 to 225.155.255.254225.155.255.25516,382
113225.156.0.0/18225.156.0.1 to 225.156.63.254225.156.63.25516,382
114225.156.64.0/18225.156.64.1 to 225.156.127.254225.156.127.25516,382
115225.156.128.0/18225.156.128.1 to 225.156.191.254225.156.191.25516,382
116225.156.192.0/18225.156.192.1 to 225.156.255.254225.156.255.25516,382
117225.157.0.0/18225.157.0.1 to 225.157.63.254225.157.63.25516,382
118225.157.64.0/18225.157.64.1 to 225.157.127.254225.157.127.25516,382
119225.157.128.0/18225.157.128.1 to 225.157.191.254225.157.191.25516,382
120225.157.192.0/18225.157.192.1 to 225.157.255.254225.157.255.25516,382
121225.158.0.0/18225.158.0.1 to 225.158.63.254225.158.63.25516,382
122225.158.64.0/18225.158.64.1 to 225.158.127.254225.158.127.25516,382
123225.158.128.0/18225.158.128.1 to 225.158.191.254225.158.191.25516,382
124225.158.192.0/18225.158.192.1 to 225.158.255.254225.158.255.25516,382
125225.159.0.0/18225.159.0.1 to 225.159.63.254225.159.63.25516,382
126225.159.64.0/18225.159.64.1 to 225.159.127.254225.159.127.25516,382
127225.159.128.0/18225.159.128.1 to 225.159.191.254225.159.191.25516,382
128225.159.192.0/18225.159.192.1 to 225.159.255.254225.159.255.25516,382

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.