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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.

Network208.232.0.0/13
Usable hosts524,286
Subnet mask255.248.0.0
Addresses524,288
Network address
208.232.0.0
Broadcast address
208.239.255.255
First usable
208.232.0.1
Last usable
208.239.255.254
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
C (default /24)
As numbers
Hex D0E80000 · Integer 3504865280 to 3505389567
Reverse DNS zones
232.208.in-addr.arpa
233.208.in-addr.arpa
234.208.in-addr.arpa
235.208.in-addr.arpa
236.208.in-addr.arpa
237.208.in-addr.arpa
238.208.in-addr.arpa
239.208.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
Address11010000.11101000.00000000.00000000208.232.0.0
Subnet mask11111111.11111000.00000000.00000000255.248.0.0
Network11010000.11101000.00000000.00000000208.232.0.0
Broadcast11010000.11101111.11111111.11111111208.239.255.255
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)

208.232.0.0/13 makes 128 subnets of /20.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1208.232.0.0/20208.232.0.1 to 208.232.15.254208.232.15.2554,094
2208.232.16.0/20208.232.16.1 to 208.232.31.254208.232.31.2554,094
3208.232.32.0/20208.232.32.1 to 208.232.47.254208.232.47.2554,094
4208.232.48.0/20208.232.48.1 to 208.232.63.254208.232.63.2554,094
5208.232.64.0/20208.232.64.1 to 208.232.79.254208.232.79.2554,094
6208.232.80.0/20208.232.80.1 to 208.232.95.254208.232.95.2554,094
7208.232.96.0/20208.232.96.1 to 208.232.111.254208.232.111.2554,094
8208.232.112.0/20208.232.112.1 to 208.232.127.254208.232.127.2554,094
9208.232.128.0/20208.232.128.1 to 208.232.143.254208.232.143.2554,094
10208.232.144.0/20208.232.144.1 to 208.232.159.254208.232.159.2554,094
11208.232.160.0/20208.232.160.1 to 208.232.175.254208.232.175.2554,094
12208.232.176.0/20208.232.176.1 to 208.232.191.254208.232.191.2554,094
13208.232.192.0/20208.232.192.1 to 208.232.207.254208.232.207.2554,094
14208.232.208.0/20208.232.208.1 to 208.232.223.254208.232.223.2554,094
15208.232.224.0/20208.232.224.1 to 208.232.239.254208.232.239.2554,094
16208.232.240.0/20208.232.240.1 to 208.232.255.254208.232.255.2554,094
17208.233.0.0/20208.233.0.1 to 208.233.15.254208.233.15.2554,094
18208.233.16.0/20208.233.16.1 to 208.233.31.254208.233.31.2554,094
19208.233.32.0/20208.233.32.1 to 208.233.47.254208.233.47.2554,094
20208.233.48.0/20208.233.48.1 to 208.233.63.254208.233.63.2554,094
21208.233.64.0/20208.233.64.1 to 208.233.79.254208.233.79.2554,094
22208.233.80.0/20208.233.80.1 to 208.233.95.254208.233.95.2554,094
23208.233.96.0/20208.233.96.1 to 208.233.111.254208.233.111.2554,094
24208.233.112.0/20208.233.112.1 to 208.233.127.254208.233.127.2554,094
25208.233.128.0/20208.233.128.1 to 208.233.143.254208.233.143.2554,094
26208.233.144.0/20208.233.144.1 to 208.233.159.254208.233.159.2554,094
27208.233.160.0/20208.233.160.1 to 208.233.175.254208.233.175.2554,094
28208.233.176.0/20208.233.176.1 to 208.233.191.254208.233.191.2554,094
29208.233.192.0/20208.233.192.1 to 208.233.207.254208.233.207.2554,094
30208.233.208.0/20208.233.208.1 to 208.233.223.254208.233.223.2554,094
31208.233.224.0/20208.233.224.1 to 208.233.239.254208.233.239.2554,094
32208.233.240.0/20208.233.240.1 to 208.233.255.254208.233.255.2554,094
33208.234.0.0/20208.234.0.1 to 208.234.15.254208.234.15.2554,094
34208.234.16.0/20208.234.16.1 to 208.234.31.254208.234.31.2554,094
35208.234.32.0/20208.234.32.1 to 208.234.47.254208.234.47.2554,094
36208.234.48.0/20208.234.48.1 to 208.234.63.254208.234.63.2554,094
37208.234.64.0/20208.234.64.1 to 208.234.79.254208.234.79.2554,094
38208.234.80.0/20208.234.80.1 to 208.234.95.254208.234.95.2554,094
39208.234.96.0/20208.234.96.1 to 208.234.111.254208.234.111.2554,094
40208.234.112.0/20208.234.112.1 to 208.234.127.254208.234.127.2554,094
41208.234.128.0/20208.234.128.1 to 208.234.143.254208.234.143.2554,094
42208.234.144.0/20208.234.144.1 to 208.234.159.254208.234.159.2554,094
43208.234.160.0/20208.234.160.1 to 208.234.175.254208.234.175.2554,094
44208.234.176.0/20208.234.176.1 to 208.234.191.254208.234.191.2554,094
45208.234.192.0/20208.234.192.1 to 208.234.207.254208.234.207.2554,094
46208.234.208.0/20208.234.208.1 to 208.234.223.254208.234.223.2554,094
47208.234.224.0/20208.234.224.1 to 208.234.239.254208.234.239.2554,094
48208.234.240.0/20208.234.240.1 to 208.234.255.254208.234.255.2554,094
49208.235.0.0/20208.235.0.1 to 208.235.15.254208.235.15.2554,094
50208.235.16.0/20208.235.16.1 to 208.235.31.254208.235.31.2554,094
51208.235.32.0/20208.235.32.1 to 208.235.47.254208.235.47.2554,094
52208.235.48.0/20208.235.48.1 to 208.235.63.254208.235.63.2554,094
53208.235.64.0/20208.235.64.1 to 208.235.79.254208.235.79.2554,094
54208.235.80.0/20208.235.80.1 to 208.235.95.254208.235.95.2554,094
55208.235.96.0/20208.235.96.1 to 208.235.111.254208.235.111.2554,094
56208.235.112.0/20208.235.112.1 to 208.235.127.254208.235.127.2554,094
57208.235.128.0/20208.235.128.1 to 208.235.143.254208.235.143.2554,094
58208.235.144.0/20208.235.144.1 to 208.235.159.254208.235.159.2554,094
59208.235.160.0/20208.235.160.1 to 208.235.175.254208.235.175.2554,094
60208.235.176.0/20208.235.176.1 to 208.235.191.254208.235.191.2554,094
61208.235.192.0/20208.235.192.1 to 208.235.207.254208.235.207.2554,094
62208.235.208.0/20208.235.208.1 to 208.235.223.254208.235.223.2554,094
63208.235.224.0/20208.235.224.1 to 208.235.239.254208.235.239.2554,094
64208.235.240.0/20208.235.240.1 to 208.235.255.254208.235.255.2554,094
65208.236.0.0/20208.236.0.1 to 208.236.15.254208.236.15.2554,094
66208.236.16.0/20208.236.16.1 to 208.236.31.254208.236.31.2554,094
67208.236.32.0/20208.236.32.1 to 208.236.47.254208.236.47.2554,094
68208.236.48.0/20208.236.48.1 to 208.236.63.254208.236.63.2554,094
69208.236.64.0/20208.236.64.1 to 208.236.79.254208.236.79.2554,094
70208.236.80.0/20208.236.80.1 to 208.236.95.254208.236.95.2554,094
71208.236.96.0/20208.236.96.1 to 208.236.111.254208.236.111.2554,094
72208.236.112.0/20208.236.112.1 to 208.236.127.254208.236.127.2554,094
73208.236.128.0/20208.236.128.1 to 208.236.143.254208.236.143.2554,094
74208.236.144.0/20208.236.144.1 to 208.236.159.254208.236.159.2554,094
75208.236.160.0/20208.236.160.1 to 208.236.175.254208.236.175.2554,094
76208.236.176.0/20208.236.176.1 to 208.236.191.254208.236.191.2554,094
77208.236.192.0/20208.236.192.1 to 208.236.207.254208.236.207.2554,094
78208.236.208.0/20208.236.208.1 to 208.236.223.254208.236.223.2554,094
79208.236.224.0/20208.236.224.1 to 208.236.239.254208.236.239.2554,094
80208.236.240.0/20208.236.240.1 to 208.236.255.254208.236.255.2554,094
81208.237.0.0/20208.237.0.1 to 208.237.15.254208.237.15.2554,094
82208.237.16.0/20208.237.16.1 to 208.237.31.254208.237.31.2554,094
83208.237.32.0/20208.237.32.1 to 208.237.47.254208.237.47.2554,094
84208.237.48.0/20208.237.48.1 to 208.237.63.254208.237.63.2554,094
85208.237.64.0/20208.237.64.1 to 208.237.79.254208.237.79.2554,094
86208.237.80.0/20208.237.80.1 to 208.237.95.254208.237.95.2554,094
87208.237.96.0/20208.237.96.1 to 208.237.111.254208.237.111.2554,094
88208.237.112.0/20208.237.112.1 to 208.237.127.254208.237.127.2554,094
89208.237.128.0/20208.237.128.1 to 208.237.143.254208.237.143.2554,094
90208.237.144.0/20208.237.144.1 to 208.237.159.254208.237.159.2554,094
91208.237.160.0/20208.237.160.1 to 208.237.175.254208.237.175.2554,094
92208.237.176.0/20208.237.176.1 to 208.237.191.254208.237.191.2554,094
93208.237.192.0/20208.237.192.1 to 208.237.207.254208.237.207.2554,094
94208.237.208.0/20208.237.208.1 to 208.237.223.254208.237.223.2554,094
95208.237.224.0/20208.237.224.1 to 208.237.239.254208.237.239.2554,094
96208.237.240.0/20208.237.240.1 to 208.237.255.254208.237.255.2554,094
97208.238.0.0/20208.238.0.1 to 208.238.15.254208.238.15.2554,094
98208.238.16.0/20208.238.16.1 to 208.238.31.254208.238.31.2554,094
99208.238.32.0/20208.238.32.1 to 208.238.47.254208.238.47.2554,094
100208.238.48.0/20208.238.48.1 to 208.238.63.254208.238.63.2554,094
101208.238.64.0/20208.238.64.1 to 208.238.79.254208.238.79.2554,094
102208.238.80.0/20208.238.80.1 to 208.238.95.254208.238.95.2554,094
103208.238.96.0/20208.238.96.1 to 208.238.111.254208.238.111.2554,094
104208.238.112.0/20208.238.112.1 to 208.238.127.254208.238.127.2554,094
105208.238.128.0/20208.238.128.1 to 208.238.143.254208.238.143.2554,094
106208.238.144.0/20208.238.144.1 to 208.238.159.254208.238.159.2554,094
107208.238.160.0/20208.238.160.1 to 208.238.175.254208.238.175.2554,094
108208.238.176.0/20208.238.176.1 to 208.238.191.254208.238.191.2554,094
109208.238.192.0/20208.238.192.1 to 208.238.207.254208.238.207.2554,094
110208.238.208.0/20208.238.208.1 to 208.238.223.254208.238.223.2554,094
111208.238.224.0/20208.238.224.1 to 208.238.239.254208.238.239.2554,094
112208.238.240.0/20208.238.240.1 to 208.238.255.254208.238.255.2554,094
113208.239.0.0/20208.239.0.1 to 208.239.15.254208.239.15.2554,094
114208.239.16.0/20208.239.16.1 to 208.239.31.254208.239.31.2554,094
115208.239.32.0/20208.239.32.1 to 208.239.47.254208.239.47.2554,094
116208.239.48.0/20208.239.48.1 to 208.239.63.254208.239.63.2554,094
117208.239.64.0/20208.239.64.1 to 208.239.79.254208.239.79.2554,094
118208.239.80.0/20208.239.80.1 to 208.239.95.254208.239.95.2554,094
119208.239.96.0/20208.239.96.1 to 208.239.111.254208.239.111.2554,094
120208.239.112.0/20208.239.112.1 to 208.239.127.254208.239.127.2554,094
121208.239.128.0/20208.239.128.1 to 208.239.143.254208.239.143.2554,094
122208.239.144.0/20208.239.144.1 to 208.239.159.254208.239.159.2554,094
123208.239.160.0/20208.239.160.1 to 208.239.175.254208.239.175.2554,094
124208.239.176.0/20208.239.176.1 to 208.239.191.254208.239.191.2554,094
125208.239.192.0/20208.239.192.1 to 208.239.207.254208.239.207.2554,094
126208.239.208.0/20208.239.208.1 to 208.239.223.254208.239.223.2554,094
127208.239.224.0/20208.239.224.1 to 208.239.239.254208.239.239.2554,094
128208.239.240.0/20208.239.240.1 to 208.239.255.254208.239.255.2554,094

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.