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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.

Network113.72.0.0/13
Usable hosts524,286
Subnet mask255.248.0.0
Addresses524,288
Network address
113.72.0.0
Broadcast address
113.79.255.255
First usable
113.72.0.1
Last usable
113.79.255.254
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
A (default /8)
As numbers
Hex 71480000 · Integer 1900544000 to 1901068287
Reverse DNS zones
72.113.in-addr.arpa
73.113.in-addr.arpa
74.113.in-addr.arpa
75.113.in-addr.arpa
76.113.in-addr.arpa
77.113.in-addr.arpa
78.113.in-addr.arpa
79.113.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
Address01110001.01001000.00000000.00000000113.72.0.0
Subnet mask11111111.11111000.00000000.00000000255.248.0.0
Network01110001.01001000.00000000.00000000113.72.0.0
Broadcast01110001.01001111.11111111.11111111113.79.255.255
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)

113.72.0.0/13 makes 128 subnets of /20.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1113.72.0.0/20113.72.0.1 to 113.72.15.254113.72.15.2554,094
2113.72.16.0/20113.72.16.1 to 113.72.31.254113.72.31.2554,094
3113.72.32.0/20113.72.32.1 to 113.72.47.254113.72.47.2554,094
4113.72.48.0/20113.72.48.1 to 113.72.63.254113.72.63.2554,094
5113.72.64.0/20113.72.64.1 to 113.72.79.254113.72.79.2554,094
6113.72.80.0/20113.72.80.1 to 113.72.95.254113.72.95.2554,094
7113.72.96.0/20113.72.96.1 to 113.72.111.254113.72.111.2554,094
8113.72.112.0/20113.72.112.1 to 113.72.127.254113.72.127.2554,094
9113.72.128.0/20113.72.128.1 to 113.72.143.254113.72.143.2554,094
10113.72.144.0/20113.72.144.1 to 113.72.159.254113.72.159.2554,094
11113.72.160.0/20113.72.160.1 to 113.72.175.254113.72.175.2554,094
12113.72.176.0/20113.72.176.1 to 113.72.191.254113.72.191.2554,094
13113.72.192.0/20113.72.192.1 to 113.72.207.254113.72.207.2554,094
14113.72.208.0/20113.72.208.1 to 113.72.223.254113.72.223.2554,094
15113.72.224.0/20113.72.224.1 to 113.72.239.254113.72.239.2554,094
16113.72.240.0/20113.72.240.1 to 113.72.255.254113.72.255.2554,094
17113.73.0.0/20113.73.0.1 to 113.73.15.254113.73.15.2554,094
18113.73.16.0/20113.73.16.1 to 113.73.31.254113.73.31.2554,094
19113.73.32.0/20113.73.32.1 to 113.73.47.254113.73.47.2554,094
20113.73.48.0/20113.73.48.1 to 113.73.63.254113.73.63.2554,094
21113.73.64.0/20113.73.64.1 to 113.73.79.254113.73.79.2554,094
22113.73.80.0/20113.73.80.1 to 113.73.95.254113.73.95.2554,094
23113.73.96.0/20113.73.96.1 to 113.73.111.254113.73.111.2554,094
24113.73.112.0/20113.73.112.1 to 113.73.127.254113.73.127.2554,094
25113.73.128.0/20113.73.128.1 to 113.73.143.254113.73.143.2554,094
26113.73.144.0/20113.73.144.1 to 113.73.159.254113.73.159.2554,094
27113.73.160.0/20113.73.160.1 to 113.73.175.254113.73.175.2554,094
28113.73.176.0/20113.73.176.1 to 113.73.191.254113.73.191.2554,094
29113.73.192.0/20113.73.192.1 to 113.73.207.254113.73.207.2554,094
30113.73.208.0/20113.73.208.1 to 113.73.223.254113.73.223.2554,094
31113.73.224.0/20113.73.224.1 to 113.73.239.254113.73.239.2554,094
32113.73.240.0/20113.73.240.1 to 113.73.255.254113.73.255.2554,094
33113.74.0.0/20113.74.0.1 to 113.74.15.254113.74.15.2554,094
34113.74.16.0/20113.74.16.1 to 113.74.31.254113.74.31.2554,094
35113.74.32.0/20113.74.32.1 to 113.74.47.254113.74.47.2554,094
36113.74.48.0/20113.74.48.1 to 113.74.63.254113.74.63.2554,094
37113.74.64.0/20113.74.64.1 to 113.74.79.254113.74.79.2554,094
38113.74.80.0/20113.74.80.1 to 113.74.95.254113.74.95.2554,094
39113.74.96.0/20113.74.96.1 to 113.74.111.254113.74.111.2554,094
40113.74.112.0/20113.74.112.1 to 113.74.127.254113.74.127.2554,094
41113.74.128.0/20113.74.128.1 to 113.74.143.254113.74.143.2554,094
42113.74.144.0/20113.74.144.1 to 113.74.159.254113.74.159.2554,094
43113.74.160.0/20113.74.160.1 to 113.74.175.254113.74.175.2554,094
44113.74.176.0/20113.74.176.1 to 113.74.191.254113.74.191.2554,094
45113.74.192.0/20113.74.192.1 to 113.74.207.254113.74.207.2554,094
46113.74.208.0/20113.74.208.1 to 113.74.223.254113.74.223.2554,094
47113.74.224.0/20113.74.224.1 to 113.74.239.254113.74.239.2554,094
48113.74.240.0/20113.74.240.1 to 113.74.255.254113.74.255.2554,094
49113.75.0.0/20113.75.0.1 to 113.75.15.254113.75.15.2554,094
50113.75.16.0/20113.75.16.1 to 113.75.31.254113.75.31.2554,094
51113.75.32.0/20113.75.32.1 to 113.75.47.254113.75.47.2554,094
52113.75.48.0/20113.75.48.1 to 113.75.63.254113.75.63.2554,094
53113.75.64.0/20113.75.64.1 to 113.75.79.254113.75.79.2554,094
54113.75.80.0/20113.75.80.1 to 113.75.95.254113.75.95.2554,094
55113.75.96.0/20113.75.96.1 to 113.75.111.254113.75.111.2554,094
56113.75.112.0/20113.75.112.1 to 113.75.127.254113.75.127.2554,094
57113.75.128.0/20113.75.128.1 to 113.75.143.254113.75.143.2554,094
58113.75.144.0/20113.75.144.1 to 113.75.159.254113.75.159.2554,094
59113.75.160.0/20113.75.160.1 to 113.75.175.254113.75.175.2554,094
60113.75.176.0/20113.75.176.1 to 113.75.191.254113.75.191.2554,094
61113.75.192.0/20113.75.192.1 to 113.75.207.254113.75.207.2554,094
62113.75.208.0/20113.75.208.1 to 113.75.223.254113.75.223.2554,094
63113.75.224.0/20113.75.224.1 to 113.75.239.254113.75.239.2554,094
64113.75.240.0/20113.75.240.1 to 113.75.255.254113.75.255.2554,094
65113.76.0.0/20113.76.0.1 to 113.76.15.254113.76.15.2554,094
66113.76.16.0/20113.76.16.1 to 113.76.31.254113.76.31.2554,094
67113.76.32.0/20113.76.32.1 to 113.76.47.254113.76.47.2554,094
68113.76.48.0/20113.76.48.1 to 113.76.63.254113.76.63.2554,094
69113.76.64.0/20113.76.64.1 to 113.76.79.254113.76.79.2554,094
70113.76.80.0/20113.76.80.1 to 113.76.95.254113.76.95.2554,094
71113.76.96.0/20113.76.96.1 to 113.76.111.254113.76.111.2554,094
72113.76.112.0/20113.76.112.1 to 113.76.127.254113.76.127.2554,094
73113.76.128.0/20113.76.128.1 to 113.76.143.254113.76.143.2554,094
74113.76.144.0/20113.76.144.1 to 113.76.159.254113.76.159.2554,094
75113.76.160.0/20113.76.160.1 to 113.76.175.254113.76.175.2554,094
76113.76.176.0/20113.76.176.1 to 113.76.191.254113.76.191.2554,094
77113.76.192.0/20113.76.192.1 to 113.76.207.254113.76.207.2554,094
78113.76.208.0/20113.76.208.1 to 113.76.223.254113.76.223.2554,094
79113.76.224.0/20113.76.224.1 to 113.76.239.254113.76.239.2554,094
80113.76.240.0/20113.76.240.1 to 113.76.255.254113.76.255.2554,094
81113.77.0.0/20113.77.0.1 to 113.77.15.254113.77.15.2554,094
82113.77.16.0/20113.77.16.1 to 113.77.31.254113.77.31.2554,094
83113.77.32.0/20113.77.32.1 to 113.77.47.254113.77.47.2554,094
84113.77.48.0/20113.77.48.1 to 113.77.63.254113.77.63.2554,094
85113.77.64.0/20113.77.64.1 to 113.77.79.254113.77.79.2554,094
86113.77.80.0/20113.77.80.1 to 113.77.95.254113.77.95.2554,094
87113.77.96.0/20113.77.96.1 to 113.77.111.254113.77.111.2554,094
88113.77.112.0/20113.77.112.1 to 113.77.127.254113.77.127.2554,094
89113.77.128.0/20113.77.128.1 to 113.77.143.254113.77.143.2554,094
90113.77.144.0/20113.77.144.1 to 113.77.159.254113.77.159.2554,094
91113.77.160.0/20113.77.160.1 to 113.77.175.254113.77.175.2554,094
92113.77.176.0/20113.77.176.1 to 113.77.191.254113.77.191.2554,094
93113.77.192.0/20113.77.192.1 to 113.77.207.254113.77.207.2554,094
94113.77.208.0/20113.77.208.1 to 113.77.223.254113.77.223.2554,094
95113.77.224.0/20113.77.224.1 to 113.77.239.254113.77.239.2554,094
96113.77.240.0/20113.77.240.1 to 113.77.255.254113.77.255.2554,094
97113.78.0.0/20113.78.0.1 to 113.78.15.254113.78.15.2554,094
98113.78.16.0/20113.78.16.1 to 113.78.31.254113.78.31.2554,094
99113.78.32.0/20113.78.32.1 to 113.78.47.254113.78.47.2554,094
100113.78.48.0/20113.78.48.1 to 113.78.63.254113.78.63.2554,094
101113.78.64.0/20113.78.64.1 to 113.78.79.254113.78.79.2554,094
102113.78.80.0/20113.78.80.1 to 113.78.95.254113.78.95.2554,094
103113.78.96.0/20113.78.96.1 to 113.78.111.254113.78.111.2554,094
104113.78.112.0/20113.78.112.1 to 113.78.127.254113.78.127.2554,094
105113.78.128.0/20113.78.128.1 to 113.78.143.254113.78.143.2554,094
106113.78.144.0/20113.78.144.1 to 113.78.159.254113.78.159.2554,094
107113.78.160.0/20113.78.160.1 to 113.78.175.254113.78.175.2554,094
108113.78.176.0/20113.78.176.1 to 113.78.191.254113.78.191.2554,094
109113.78.192.0/20113.78.192.1 to 113.78.207.254113.78.207.2554,094
110113.78.208.0/20113.78.208.1 to 113.78.223.254113.78.223.2554,094
111113.78.224.0/20113.78.224.1 to 113.78.239.254113.78.239.2554,094
112113.78.240.0/20113.78.240.1 to 113.78.255.254113.78.255.2554,094
113113.79.0.0/20113.79.0.1 to 113.79.15.254113.79.15.2554,094
114113.79.16.0/20113.79.16.1 to 113.79.31.254113.79.31.2554,094
115113.79.32.0/20113.79.32.1 to 113.79.47.254113.79.47.2554,094
116113.79.48.0/20113.79.48.1 to 113.79.63.254113.79.63.2554,094
117113.79.64.0/20113.79.64.1 to 113.79.79.254113.79.79.2554,094
118113.79.80.0/20113.79.80.1 to 113.79.95.254113.79.95.2554,094
119113.79.96.0/20113.79.96.1 to 113.79.111.254113.79.111.2554,094
120113.79.112.0/20113.79.112.1 to 113.79.127.254113.79.127.2554,094
121113.79.128.0/20113.79.128.1 to 113.79.143.254113.79.143.2554,094
122113.79.144.0/20113.79.144.1 to 113.79.159.254113.79.159.2554,094
123113.79.160.0/20113.79.160.1 to 113.79.175.254113.79.175.2554,094
124113.79.176.0/20113.79.176.1 to 113.79.191.254113.79.191.2554,094
125113.79.192.0/20113.79.192.1 to 113.79.207.254113.79.207.2554,094
126113.79.208.0/20113.79.208.1 to 113.79.223.254113.79.223.2554,094
127113.79.224.0/20113.79.224.1 to 113.79.239.254113.79.239.2554,094
128113.79.240.0/20113.79.240.1 to 113.79.255.254113.79.255.2554,094

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.