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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.

Network238.64.0.0/13
Usable hosts524,286
Subnet mask255.248.0.0
Addresses524,288
Network address
238.64.0.0
Broadcast address
238.71.255.255
First usable
238.64.0.1
Last usable
238.71.255.254
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
Multicast 224.0.0.0/4
One-to-many traffic, such as IPTV and routing protocols
Old class
D (multicast)
As numbers
Hex EE400000 · Integer 3997171712 to 3997695999
Reverse DNS zones
64.238.in-addr.arpa
65.238.in-addr.arpa
66.238.in-addr.arpa
67.238.in-addr.arpa
68.238.in-addr.arpa
69.238.in-addr.arpa
70.238.in-addr.arpa
71.238.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
Address11101110.01000000.00000000.00000000238.64.0.0
Subnet mask11111111.11111000.00000000.00000000255.248.0.0
Network11101110.01000000.00000000.00000000238.64.0.0
Broadcast11101110.01000111.11111111.11111111238.71.255.255
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)

238.64.0.0/13 makes 128 subnets of /20.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1238.64.0.0/20238.64.0.1 to 238.64.15.254238.64.15.2554,094
2238.64.16.0/20238.64.16.1 to 238.64.31.254238.64.31.2554,094
3238.64.32.0/20238.64.32.1 to 238.64.47.254238.64.47.2554,094
4238.64.48.0/20238.64.48.1 to 238.64.63.254238.64.63.2554,094
5238.64.64.0/20238.64.64.1 to 238.64.79.254238.64.79.2554,094
6238.64.80.0/20238.64.80.1 to 238.64.95.254238.64.95.2554,094
7238.64.96.0/20238.64.96.1 to 238.64.111.254238.64.111.2554,094
8238.64.112.0/20238.64.112.1 to 238.64.127.254238.64.127.2554,094
9238.64.128.0/20238.64.128.1 to 238.64.143.254238.64.143.2554,094
10238.64.144.0/20238.64.144.1 to 238.64.159.254238.64.159.2554,094
11238.64.160.0/20238.64.160.1 to 238.64.175.254238.64.175.2554,094
12238.64.176.0/20238.64.176.1 to 238.64.191.254238.64.191.2554,094
13238.64.192.0/20238.64.192.1 to 238.64.207.254238.64.207.2554,094
14238.64.208.0/20238.64.208.1 to 238.64.223.254238.64.223.2554,094
15238.64.224.0/20238.64.224.1 to 238.64.239.254238.64.239.2554,094
16238.64.240.0/20238.64.240.1 to 238.64.255.254238.64.255.2554,094
17238.65.0.0/20238.65.0.1 to 238.65.15.254238.65.15.2554,094
18238.65.16.0/20238.65.16.1 to 238.65.31.254238.65.31.2554,094
19238.65.32.0/20238.65.32.1 to 238.65.47.254238.65.47.2554,094
20238.65.48.0/20238.65.48.1 to 238.65.63.254238.65.63.2554,094
21238.65.64.0/20238.65.64.1 to 238.65.79.254238.65.79.2554,094
22238.65.80.0/20238.65.80.1 to 238.65.95.254238.65.95.2554,094
23238.65.96.0/20238.65.96.1 to 238.65.111.254238.65.111.2554,094
24238.65.112.0/20238.65.112.1 to 238.65.127.254238.65.127.2554,094
25238.65.128.0/20238.65.128.1 to 238.65.143.254238.65.143.2554,094
26238.65.144.0/20238.65.144.1 to 238.65.159.254238.65.159.2554,094
27238.65.160.0/20238.65.160.1 to 238.65.175.254238.65.175.2554,094
28238.65.176.0/20238.65.176.1 to 238.65.191.254238.65.191.2554,094
29238.65.192.0/20238.65.192.1 to 238.65.207.254238.65.207.2554,094
30238.65.208.0/20238.65.208.1 to 238.65.223.254238.65.223.2554,094
31238.65.224.0/20238.65.224.1 to 238.65.239.254238.65.239.2554,094
32238.65.240.0/20238.65.240.1 to 238.65.255.254238.65.255.2554,094
33238.66.0.0/20238.66.0.1 to 238.66.15.254238.66.15.2554,094
34238.66.16.0/20238.66.16.1 to 238.66.31.254238.66.31.2554,094
35238.66.32.0/20238.66.32.1 to 238.66.47.254238.66.47.2554,094
36238.66.48.0/20238.66.48.1 to 238.66.63.254238.66.63.2554,094
37238.66.64.0/20238.66.64.1 to 238.66.79.254238.66.79.2554,094
38238.66.80.0/20238.66.80.1 to 238.66.95.254238.66.95.2554,094
39238.66.96.0/20238.66.96.1 to 238.66.111.254238.66.111.2554,094
40238.66.112.0/20238.66.112.1 to 238.66.127.254238.66.127.2554,094
41238.66.128.0/20238.66.128.1 to 238.66.143.254238.66.143.2554,094
42238.66.144.0/20238.66.144.1 to 238.66.159.254238.66.159.2554,094
43238.66.160.0/20238.66.160.1 to 238.66.175.254238.66.175.2554,094
44238.66.176.0/20238.66.176.1 to 238.66.191.254238.66.191.2554,094
45238.66.192.0/20238.66.192.1 to 238.66.207.254238.66.207.2554,094
46238.66.208.0/20238.66.208.1 to 238.66.223.254238.66.223.2554,094
47238.66.224.0/20238.66.224.1 to 238.66.239.254238.66.239.2554,094
48238.66.240.0/20238.66.240.1 to 238.66.255.254238.66.255.2554,094
49238.67.0.0/20238.67.0.1 to 238.67.15.254238.67.15.2554,094
50238.67.16.0/20238.67.16.1 to 238.67.31.254238.67.31.2554,094
51238.67.32.0/20238.67.32.1 to 238.67.47.254238.67.47.2554,094
52238.67.48.0/20238.67.48.1 to 238.67.63.254238.67.63.2554,094
53238.67.64.0/20238.67.64.1 to 238.67.79.254238.67.79.2554,094
54238.67.80.0/20238.67.80.1 to 238.67.95.254238.67.95.2554,094
55238.67.96.0/20238.67.96.1 to 238.67.111.254238.67.111.2554,094
56238.67.112.0/20238.67.112.1 to 238.67.127.254238.67.127.2554,094
57238.67.128.0/20238.67.128.1 to 238.67.143.254238.67.143.2554,094
58238.67.144.0/20238.67.144.1 to 238.67.159.254238.67.159.2554,094
59238.67.160.0/20238.67.160.1 to 238.67.175.254238.67.175.2554,094
60238.67.176.0/20238.67.176.1 to 238.67.191.254238.67.191.2554,094
61238.67.192.0/20238.67.192.1 to 238.67.207.254238.67.207.2554,094
62238.67.208.0/20238.67.208.1 to 238.67.223.254238.67.223.2554,094
63238.67.224.0/20238.67.224.1 to 238.67.239.254238.67.239.2554,094
64238.67.240.0/20238.67.240.1 to 238.67.255.254238.67.255.2554,094
65238.68.0.0/20238.68.0.1 to 238.68.15.254238.68.15.2554,094
66238.68.16.0/20238.68.16.1 to 238.68.31.254238.68.31.2554,094
67238.68.32.0/20238.68.32.1 to 238.68.47.254238.68.47.2554,094
68238.68.48.0/20238.68.48.1 to 238.68.63.254238.68.63.2554,094
69238.68.64.0/20238.68.64.1 to 238.68.79.254238.68.79.2554,094
70238.68.80.0/20238.68.80.1 to 238.68.95.254238.68.95.2554,094
71238.68.96.0/20238.68.96.1 to 238.68.111.254238.68.111.2554,094
72238.68.112.0/20238.68.112.1 to 238.68.127.254238.68.127.2554,094
73238.68.128.0/20238.68.128.1 to 238.68.143.254238.68.143.2554,094
74238.68.144.0/20238.68.144.1 to 238.68.159.254238.68.159.2554,094
75238.68.160.0/20238.68.160.1 to 238.68.175.254238.68.175.2554,094
76238.68.176.0/20238.68.176.1 to 238.68.191.254238.68.191.2554,094
77238.68.192.0/20238.68.192.1 to 238.68.207.254238.68.207.2554,094
78238.68.208.0/20238.68.208.1 to 238.68.223.254238.68.223.2554,094
79238.68.224.0/20238.68.224.1 to 238.68.239.254238.68.239.2554,094
80238.68.240.0/20238.68.240.1 to 238.68.255.254238.68.255.2554,094
81238.69.0.0/20238.69.0.1 to 238.69.15.254238.69.15.2554,094
82238.69.16.0/20238.69.16.1 to 238.69.31.254238.69.31.2554,094
83238.69.32.0/20238.69.32.1 to 238.69.47.254238.69.47.2554,094
84238.69.48.0/20238.69.48.1 to 238.69.63.254238.69.63.2554,094
85238.69.64.0/20238.69.64.1 to 238.69.79.254238.69.79.2554,094
86238.69.80.0/20238.69.80.1 to 238.69.95.254238.69.95.2554,094
87238.69.96.0/20238.69.96.1 to 238.69.111.254238.69.111.2554,094
88238.69.112.0/20238.69.112.1 to 238.69.127.254238.69.127.2554,094
89238.69.128.0/20238.69.128.1 to 238.69.143.254238.69.143.2554,094
90238.69.144.0/20238.69.144.1 to 238.69.159.254238.69.159.2554,094
91238.69.160.0/20238.69.160.1 to 238.69.175.254238.69.175.2554,094
92238.69.176.0/20238.69.176.1 to 238.69.191.254238.69.191.2554,094
93238.69.192.0/20238.69.192.1 to 238.69.207.254238.69.207.2554,094
94238.69.208.0/20238.69.208.1 to 238.69.223.254238.69.223.2554,094
95238.69.224.0/20238.69.224.1 to 238.69.239.254238.69.239.2554,094
96238.69.240.0/20238.69.240.1 to 238.69.255.254238.69.255.2554,094
97238.70.0.0/20238.70.0.1 to 238.70.15.254238.70.15.2554,094
98238.70.16.0/20238.70.16.1 to 238.70.31.254238.70.31.2554,094
99238.70.32.0/20238.70.32.1 to 238.70.47.254238.70.47.2554,094
100238.70.48.0/20238.70.48.1 to 238.70.63.254238.70.63.2554,094
101238.70.64.0/20238.70.64.1 to 238.70.79.254238.70.79.2554,094
102238.70.80.0/20238.70.80.1 to 238.70.95.254238.70.95.2554,094
103238.70.96.0/20238.70.96.1 to 238.70.111.254238.70.111.2554,094
104238.70.112.0/20238.70.112.1 to 238.70.127.254238.70.127.2554,094
105238.70.128.0/20238.70.128.1 to 238.70.143.254238.70.143.2554,094
106238.70.144.0/20238.70.144.1 to 238.70.159.254238.70.159.2554,094
107238.70.160.0/20238.70.160.1 to 238.70.175.254238.70.175.2554,094
108238.70.176.0/20238.70.176.1 to 238.70.191.254238.70.191.2554,094
109238.70.192.0/20238.70.192.1 to 238.70.207.254238.70.207.2554,094
110238.70.208.0/20238.70.208.1 to 238.70.223.254238.70.223.2554,094
111238.70.224.0/20238.70.224.1 to 238.70.239.254238.70.239.2554,094
112238.70.240.0/20238.70.240.1 to 238.70.255.254238.70.255.2554,094
113238.71.0.0/20238.71.0.1 to 238.71.15.254238.71.15.2554,094
114238.71.16.0/20238.71.16.1 to 238.71.31.254238.71.31.2554,094
115238.71.32.0/20238.71.32.1 to 238.71.47.254238.71.47.2554,094
116238.71.48.0/20238.71.48.1 to 238.71.63.254238.71.63.2554,094
117238.71.64.0/20238.71.64.1 to 238.71.79.254238.71.79.2554,094
118238.71.80.0/20238.71.80.1 to 238.71.95.254238.71.95.2554,094
119238.71.96.0/20238.71.96.1 to 238.71.111.254238.71.111.2554,094
120238.71.112.0/20238.71.112.1 to 238.71.127.254238.71.127.2554,094
121238.71.128.0/20238.71.128.1 to 238.71.143.254238.71.143.2554,094
122238.71.144.0/20238.71.144.1 to 238.71.159.254238.71.159.2554,094
123238.71.160.0/20238.71.160.1 to 238.71.175.254238.71.175.2554,094
124238.71.176.0/20238.71.176.1 to 238.71.191.254238.71.191.2554,094
125238.71.192.0/20238.71.192.1 to 238.71.207.254238.71.207.2554,094
126238.71.208.0/20238.71.208.1 to 238.71.223.254238.71.223.2554,094
127238.71.224.0/20238.71.224.1 to 238.71.239.254238.71.239.2554,094
128238.71.240.0/20238.71.240.1 to 238.71.255.254238.71.255.2554,094

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.