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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.

Network166.112.0.0/13
Usable hosts524,286
Subnet mask255.248.0.0
Addresses524,288
Network address
166.112.0.0
Broadcast address
166.119.255.255
First usable
166.112.0.1
Last usable
166.119.255.254
Usable hosts
524,286 (524,288 less the network and broadcast addresses)
Subnet mask
255.248.0.0
Wildcard mask
0.7.255.255 (Cisco ACLs, OSPF)
Prefix length
/13
Type
Public public
Old class
B (default /16)
As numbers
Hex A6700000 · Integer 2792357888 to 2792882175
Reverse DNS zones
112.166.in-addr.arpa
113.166.in-addr.arpa
114.166.in-addr.arpa
115.166.in-addr.arpa
116.166.in-addr.arpa
117.166.in-addr.arpa
118.166.in-addr.arpa
119.166.in-addr.arpa
/13 is not on a 8-bit boundary, so it takes 8 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10100110.01110000.00000000.00000000166.112.0.0
Subnet mask11111111.11111000.00000000.00000000255.248.0.0
Network10100110.01110000.00000000.00000000166.112.0.0
Broadcast10100110.01110111.11111111.11111111166.119.255.255
Split into smaller subnets/20
/14 (2)/15 (4)/16 (8)/17 (16)/18 (32)/19 (64)/20 (128)/21 (256)/22 (512)/23 (1,024)/24 (2,048)/25 (4,096)

166.112.0.0/13 makes 128 subnets of /20.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1166.112.0.0/20166.112.0.1 to 166.112.15.254166.112.15.2554,094
2166.112.16.0/20166.112.16.1 to 166.112.31.254166.112.31.2554,094
3166.112.32.0/20166.112.32.1 to 166.112.47.254166.112.47.2554,094
4166.112.48.0/20166.112.48.1 to 166.112.63.254166.112.63.2554,094
5166.112.64.0/20166.112.64.1 to 166.112.79.254166.112.79.2554,094
6166.112.80.0/20166.112.80.1 to 166.112.95.254166.112.95.2554,094
7166.112.96.0/20166.112.96.1 to 166.112.111.254166.112.111.2554,094
8166.112.112.0/20166.112.112.1 to 166.112.127.254166.112.127.2554,094
9166.112.128.0/20166.112.128.1 to 166.112.143.254166.112.143.2554,094
10166.112.144.0/20166.112.144.1 to 166.112.159.254166.112.159.2554,094
11166.112.160.0/20166.112.160.1 to 166.112.175.254166.112.175.2554,094
12166.112.176.0/20166.112.176.1 to 166.112.191.254166.112.191.2554,094
13166.112.192.0/20166.112.192.1 to 166.112.207.254166.112.207.2554,094
14166.112.208.0/20166.112.208.1 to 166.112.223.254166.112.223.2554,094
15166.112.224.0/20166.112.224.1 to 166.112.239.254166.112.239.2554,094
16166.112.240.0/20166.112.240.1 to 166.112.255.254166.112.255.2554,094
17166.113.0.0/20166.113.0.1 to 166.113.15.254166.113.15.2554,094
18166.113.16.0/20166.113.16.1 to 166.113.31.254166.113.31.2554,094
19166.113.32.0/20166.113.32.1 to 166.113.47.254166.113.47.2554,094
20166.113.48.0/20166.113.48.1 to 166.113.63.254166.113.63.2554,094
21166.113.64.0/20166.113.64.1 to 166.113.79.254166.113.79.2554,094
22166.113.80.0/20166.113.80.1 to 166.113.95.254166.113.95.2554,094
23166.113.96.0/20166.113.96.1 to 166.113.111.254166.113.111.2554,094
24166.113.112.0/20166.113.112.1 to 166.113.127.254166.113.127.2554,094
25166.113.128.0/20166.113.128.1 to 166.113.143.254166.113.143.2554,094
26166.113.144.0/20166.113.144.1 to 166.113.159.254166.113.159.2554,094
27166.113.160.0/20166.113.160.1 to 166.113.175.254166.113.175.2554,094
28166.113.176.0/20166.113.176.1 to 166.113.191.254166.113.191.2554,094
29166.113.192.0/20166.113.192.1 to 166.113.207.254166.113.207.2554,094
30166.113.208.0/20166.113.208.1 to 166.113.223.254166.113.223.2554,094
31166.113.224.0/20166.113.224.1 to 166.113.239.254166.113.239.2554,094
32166.113.240.0/20166.113.240.1 to 166.113.255.254166.113.255.2554,094
33166.114.0.0/20166.114.0.1 to 166.114.15.254166.114.15.2554,094
34166.114.16.0/20166.114.16.1 to 166.114.31.254166.114.31.2554,094
35166.114.32.0/20166.114.32.1 to 166.114.47.254166.114.47.2554,094
36166.114.48.0/20166.114.48.1 to 166.114.63.254166.114.63.2554,094
37166.114.64.0/20166.114.64.1 to 166.114.79.254166.114.79.2554,094
38166.114.80.0/20166.114.80.1 to 166.114.95.254166.114.95.2554,094
39166.114.96.0/20166.114.96.1 to 166.114.111.254166.114.111.2554,094
40166.114.112.0/20166.114.112.1 to 166.114.127.254166.114.127.2554,094
41166.114.128.0/20166.114.128.1 to 166.114.143.254166.114.143.2554,094
42166.114.144.0/20166.114.144.1 to 166.114.159.254166.114.159.2554,094
43166.114.160.0/20166.114.160.1 to 166.114.175.254166.114.175.2554,094
44166.114.176.0/20166.114.176.1 to 166.114.191.254166.114.191.2554,094
45166.114.192.0/20166.114.192.1 to 166.114.207.254166.114.207.2554,094
46166.114.208.0/20166.114.208.1 to 166.114.223.254166.114.223.2554,094
47166.114.224.0/20166.114.224.1 to 166.114.239.254166.114.239.2554,094
48166.114.240.0/20166.114.240.1 to 166.114.255.254166.114.255.2554,094
49166.115.0.0/20166.115.0.1 to 166.115.15.254166.115.15.2554,094
50166.115.16.0/20166.115.16.1 to 166.115.31.254166.115.31.2554,094
51166.115.32.0/20166.115.32.1 to 166.115.47.254166.115.47.2554,094
52166.115.48.0/20166.115.48.1 to 166.115.63.254166.115.63.2554,094
53166.115.64.0/20166.115.64.1 to 166.115.79.254166.115.79.2554,094
54166.115.80.0/20166.115.80.1 to 166.115.95.254166.115.95.2554,094
55166.115.96.0/20166.115.96.1 to 166.115.111.254166.115.111.2554,094
56166.115.112.0/20166.115.112.1 to 166.115.127.254166.115.127.2554,094
57166.115.128.0/20166.115.128.1 to 166.115.143.254166.115.143.2554,094
58166.115.144.0/20166.115.144.1 to 166.115.159.254166.115.159.2554,094
59166.115.160.0/20166.115.160.1 to 166.115.175.254166.115.175.2554,094
60166.115.176.0/20166.115.176.1 to 166.115.191.254166.115.191.2554,094
61166.115.192.0/20166.115.192.1 to 166.115.207.254166.115.207.2554,094
62166.115.208.0/20166.115.208.1 to 166.115.223.254166.115.223.2554,094
63166.115.224.0/20166.115.224.1 to 166.115.239.254166.115.239.2554,094
64166.115.240.0/20166.115.240.1 to 166.115.255.254166.115.255.2554,094
65166.116.0.0/20166.116.0.1 to 166.116.15.254166.116.15.2554,094
66166.116.16.0/20166.116.16.1 to 166.116.31.254166.116.31.2554,094
67166.116.32.0/20166.116.32.1 to 166.116.47.254166.116.47.2554,094
68166.116.48.0/20166.116.48.1 to 166.116.63.254166.116.63.2554,094
69166.116.64.0/20166.116.64.1 to 166.116.79.254166.116.79.2554,094
70166.116.80.0/20166.116.80.1 to 166.116.95.254166.116.95.2554,094
71166.116.96.0/20166.116.96.1 to 166.116.111.254166.116.111.2554,094
72166.116.112.0/20166.116.112.1 to 166.116.127.254166.116.127.2554,094
73166.116.128.0/20166.116.128.1 to 166.116.143.254166.116.143.2554,094
74166.116.144.0/20166.116.144.1 to 166.116.159.254166.116.159.2554,094
75166.116.160.0/20166.116.160.1 to 166.116.175.254166.116.175.2554,094
76166.116.176.0/20166.116.176.1 to 166.116.191.254166.116.191.2554,094
77166.116.192.0/20166.116.192.1 to 166.116.207.254166.116.207.2554,094
78166.116.208.0/20166.116.208.1 to 166.116.223.254166.116.223.2554,094
79166.116.224.0/20166.116.224.1 to 166.116.239.254166.116.239.2554,094
80166.116.240.0/20166.116.240.1 to 166.116.255.254166.116.255.2554,094
81166.117.0.0/20166.117.0.1 to 166.117.15.254166.117.15.2554,094
82166.117.16.0/20166.117.16.1 to 166.117.31.254166.117.31.2554,094
83166.117.32.0/20166.117.32.1 to 166.117.47.254166.117.47.2554,094
84166.117.48.0/20166.117.48.1 to 166.117.63.254166.117.63.2554,094
85166.117.64.0/20166.117.64.1 to 166.117.79.254166.117.79.2554,094
86166.117.80.0/20166.117.80.1 to 166.117.95.254166.117.95.2554,094
87166.117.96.0/20166.117.96.1 to 166.117.111.254166.117.111.2554,094
88166.117.112.0/20166.117.112.1 to 166.117.127.254166.117.127.2554,094
89166.117.128.0/20166.117.128.1 to 166.117.143.254166.117.143.2554,094
90166.117.144.0/20166.117.144.1 to 166.117.159.254166.117.159.2554,094
91166.117.160.0/20166.117.160.1 to 166.117.175.254166.117.175.2554,094
92166.117.176.0/20166.117.176.1 to 166.117.191.254166.117.191.2554,094
93166.117.192.0/20166.117.192.1 to 166.117.207.254166.117.207.2554,094
94166.117.208.0/20166.117.208.1 to 166.117.223.254166.117.223.2554,094
95166.117.224.0/20166.117.224.1 to 166.117.239.254166.117.239.2554,094
96166.117.240.0/20166.117.240.1 to 166.117.255.254166.117.255.2554,094
97166.118.0.0/20166.118.0.1 to 166.118.15.254166.118.15.2554,094
98166.118.16.0/20166.118.16.1 to 166.118.31.254166.118.31.2554,094
99166.118.32.0/20166.118.32.1 to 166.118.47.254166.118.47.2554,094
100166.118.48.0/20166.118.48.1 to 166.118.63.254166.118.63.2554,094
101166.118.64.0/20166.118.64.1 to 166.118.79.254166.118.79.2554,094
102166.118.80.0/20166.118.80.1 to 166.118.95.254166.118.95.2554,094
103166.118.96.0/20166.118.96.1 to 166.118.111.254166.118.111.2554,094
104166.118.112.0/20166.118.112.1 to 166.118.127.254166.118.127.2554,094
105166.118.128.0/20166.118.128.1 to 166.118.143.254166.118.143.2554,094
106166.118.144.0/20166.118.144.1 to 166.118.159.254166.118.159.2554,094
107166.118.160.0/20166.118.160.1 to 166.118.175.254166.118.175.2554,094
108166.118.176.0/20166.118.176.1 to 166.118.191.254166.118.191.2554,094
109166.118.192.0/20166.118.192.1 to 166.118.207.254166.118.207.2554,094
110166.118.208.0/20166.118.208.1 to 166.118.223.254166.118.223.2554,094
111166.118.224.0/20166.118.224.1 to 166.118.239.254166.118.239.2554,094
112166.118.240.0/20166.118.240.1 to 166.118.255.254166.118.255.2554,094
113166.119.0.0/20166.119.0.1 to 166.119.15.254166.119.15.2554,094
114166.119.16.0/20166.119.16.1 to 166.119.31.254166.119.31.2554,094
115166.119.32.0/20166.119.32.1 to 166.119.47.254166.119.47.2554,094
116166.119.48.0/20166.119.48.1 to 166.119.63.254166.119.63.2554,094
117166.119.64.0/20166.119.64.1 to 166.119.79.254166.119.79.2554,094
118166.119.80.0/20166.119.80.1 to 166.119.95.254166.119.95.2554,094
119166.119.96.0/20166.119.96.1 to 166.119.111.254166.119.111.2554,094
120166.119.112.0/20166.119.112.1 to 166.119.127.254166.119.127.2554,094
121166.119.128.0/20166.119.128.1 to 166.119.143.254166.119.143.2554,094
122166.119.144.0/20166.119.144.1 to 166.119.159.254166.119.159.2554,094
123166.119.160.0/20166.119.160.1 to 166.119.175.254166.119.175.2554,094
124166.119.176.0/20166.119.176.1 to 166.119.191.254166.119.191.2554,094
125166.119.192.0/20166.119.192.1 to 166.119.207.254166.119.207.2554,094
126166.119.208.0/20166.119.208.1 to 166.119.223.254166.119.223.2554,094
127166.119.224.0/20166.119.224.1 to 166.119.239.254166.119.239.2554,094
128166.119.240.0/20166.119.240.1 to 166.119.255.254166.119.255.2554,094

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.