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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.

Network213.0.0.0/13
Usable hosts524,286
Subnet mask255.248.0.0
Addresses524,288
Network address
213.0.0.0
Broadcast address
213.7.255.255
First usable
213.0.0.1
Last usable
213.7.255.254
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 D5000000 · Integer 3573547008 to 3574071295
Reverse DNS zones
0.213.in-addr.arpa
1.213.in-addr.arpa
2.213.in-addr.arpa
3.213.in-addr.arpa
4.213.in-addr.arpa
5.213.in-addr.arpa
6.213.in-addr.arpa
7.213.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
Address11010101.00000000.00000000.00000000213.0.0.0
Subnet mask11111111.11111000.00000000.00000000255.248.0.0
Network11010101.00000000.00000000.00000000213.0.0.0
Broadcast11010101.00000111.11111111.11111111213.7.255.255
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)

213.0.0.0/13 makes 128 subnets of /20.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1213.0.0.0/20213.0.0.1 to 213.0.15.254213.0.15.2554,094
2213.0.16.0/20213.0.16.1 to 213.0.31.254213.0.31.2554,094
3213.0.32.0/20213.0.32.1 to 213.0.47.254213.0.47.2554,094
4213.0.48.0/20213.0.48.1 to 213.0.63.254213.0.63.2554,094
5213.0.64.0/20213.0.64.1 to 213.0.79.254213.0.79.2554,094
6213.0.80.0/20213.0.80.1 to 213.0.95.254213.0.95.2554,094
7213.0.96.0/20213.0.96.1 to 213.0.111.254213.0.111.2554,094
8213.0.112.0/20213.0.112.1 to 213.0.127.254213.0.127.2554,094
9213.0.128.0/20213.0.128.1 to 213.0.143.254213.0.143.2554,094
10213.0.144.0/20213.0.144.1 to 213.0.159.254213.0.159.2554,094
11213.0.160.0/20213.0.160.1 to 213.0.175.254213.0.175.2554,094
12213.0.176.0/20213.0.176.1 to 213.0.191.254213.0.191.2554,094
13213.0.192.0/20213.0.192.1 to 213.0.207.254213.0.207.2554,094
14213.0.208.0/20213.0.208.1 to 213.0.223.254213.0.223.2554,094
15213.0.224.0/20213.0.224.1 to 213.0.239.254213.0.239.2554,094
16213.0.240.0/20213.0.240.1 to 213.0.255.254213.0.255.2554,094
17213.1.0.0/20213.1.0.1 to 213.1.15.254213.1.15.2554,094
18213.1.16.0/20213.1.16.1 to 213.1.31.254213.1.31.2554,094
19213.1.32.0/20213.1.32.1 to 213.1.47.254213.1.47.2554,094
20213.1.48.0/20213.1.48.1 to 213.1.63.254213.1.63.2554,094
21213.1.64.0/20213.1.64.1 to 213.1.79.254213.1.79.2554,094
22213.1.80.0/20213.1.80.1 to 213.1.95.254213.1.95.2554,094
23213.1.96.0/20213.1.96.1 to 213.1.111.254213.1.111.2554,094
24213.1.112.0/20213.1.112.1 to 213.1.127.254213.1.127.2554,094
25213.1.128.0/20213.1.128.1 to 213.1.143.254213.1.143.2554,094
26213.1.144.0/20213.1.144.1 to 213.1.159.254213.1.159.2554,094
27213.1.160.0/20213.1.160.1 to 213.1.175.254213.1.175.2554,094
28213.1.176.0/20213.1.176.1 to 213.1.191.254213.1.191.2554,094
29213.1.192.0/20213.1.192.1 to 213.1.207.254213.1.207.2554,094
30213.1.208.0/20213.1.208.1 to 213.1.223.254213.1.223.2554,094
31213.1.224.0/20213.1.224.1 to 213.1.239.254213.1.239.2554,094
32213.1.240.0/20213.1.240.1 to 213.1.255.254213.1.255.2554,094
33213.2.0.0/20213.2.0.1 to 213.2.15.254213.2.15.2554,094
34213.2.16.0/20213.2.16.1 to 213.2.31.254213.2.31.2554,094
35213.2.32.0/20213.2.32.1 to 213.2.47.254213.2.47.2554,094
36213.2.48.0/20213.2.48.1 to 213.2.63.254213.2.63.2554,094
37213.2.64.0/20213.2.64.1 to 213.2.79.254213.2.79.2554,094
38213.2.80.0/20213.2.80.1 to 213.2.95.254213.2.95.2554,094
39213.2.96.0/20213.2.96.1 to 213.2.111.254213.2.111.2554,094
40213.2.112.0/20213.2.112.1 to 213.2.127.254213.2.127.2554,094
41213.2.128.0/20213.2.128.1 to 213.2.143.254213.2.143.2554,094
42213.2.144.0/20213.2.144.1 to 213.2.159.254213.2.159.2554,094
43213.2.160.0/20213.2.160.1 to 213.2.175.254213.2.175.2554,094
44213.2.176.0/20213.2.176.1 to 213.2.191.254213.2.191.2554,094
45213.2.192.0/20213.2.192.1 to 213.2.207.254213.2.207.2554,094
46213.2.208.0/20213.2.208.1 to 213.2.223.254213.2.223.2554,094
47213.2.224.0/20213.2.224.1 to 213.2.239.254213.2.239.2554,094
48213.2.240.0/20213.2.240.1 to 213.2.255.254213.2.255.2554,094
49213.3.0.0/20213.3.0.1 to 213.3.15.254213.3.15.2554,094
50213.3.16.0/20213.3.16.1 to 213.3.31.254213.3.31.2554,094
51213.3.32.0/20213.3.32.1 to 213.3.47.254213.3.47.2554,094
52213.3.48.0/20213.3.48.1 to 213.3.63.254213.3.63.2554,094
53213.3.64.0/20213.3.64.1 to 213.3.79.254213.3.79.2554,094
54213.3.80.0/20213.3.80.1 to 213.3.95.254213.3.95.2554,094
55213.3.96.0/20213.3.96.1 to 213.3.111.254213.3.111.2554,094
56213.3.112.0/20213.3.112.1 to 213.3.127.254213.3.127.2554,094
57213.3.128.0/20213.3.128.1 to 213.3.143.254213.3.143.2554,094
58213.3.144.0/20213.3.144.1 to 213.3.159.254213.3.159.2554,094
59213.3.160.0/20213.3.160.1 to 213.3.175.254213.3.175.2554,094
60213.3.176.0/20213.3.176.1 to 213.3.191.254213.3.191.2554,094
61213.3.192.0/20213.3.192.1 to 213.3.207.254213.3.207.2554,094
62213.3.208.0/20213.3.208.1 to 213.3.223.254213.3.223.2554,094
63213.3.224.0/20213.3.224.1 to 213.3.239.254213.3.239.2554,094
64213.3.240.0/20213.3.240.1 to 213.3.255.254213.3.255.2554,094
65213.4.0.0/20213.4.0.1 to 213.4.15.254213.4.15.2554,094
66213.4.16.0/20213.4.16.1 to 213.4.31.254213.4.31.2554,094
67213.4.32.0/20213.4.32.1 to 213.4.47.254213.4.47.2554,094
68213.4.48.0/20213.4.48.1 to 213.4.63.254213.4.63.2554,094
69213.4.64.0/20213.4.64.1 to 213.4.79.254213.4.79.2554,094
70213.4.80.0/20213.4.80.1 to 213.4.95.254213.4.95.2554,094
71213.4.96.0/20213.4.96.1 to 213.4.111.254213.4.111.2554,094
72213.4.112.0/20213.4.112.1 to 213.4.127.254213.4.127.2554,094
73213.4.128.0/20213.4.128.1 to 213.4.143.254213.4.143.2554,094
74213.4.144.0/20213.4.144.1 to 213.4.159.254213.4.159.2554,094
75213.4.160.0/20213.4.160.1 to 213.4.175.254213.4.175.2554,094
76213.4.176.0/20213.4.176.1 to 213.4.191.254213.4.191.2554,094
77213.4.192.0/20213.4.192.1 to 213.4.207.254213.4.207.2554,094
78213.4.208.0/20213.4.208.1 to 213.4.223.254213.4.223.2554,094
79213.4.224.0/20213.4.224.1 to 213.4.239.254213.4.239.2554,094
80213.4.240.0/20213.4.240.1 to 213.4.255.254213.4.255.2554,094
81213.5.0.0/20213.5.0.1 to 213.5.15.254213.5.15.2554,094
82213.5.16.0/20213.5.16.1 to 213.5.31.254213.5.31.2554,094
83213.5.32.0/20213.5.32.1 to 213.5.47.254213.5.47.2554,094
84213.5.48.0/20213.5.48.1 to 213.5.63.254213.5.63.2554,094
85213.5.64.0/20213.5.64.1 to 213.5.79.254213.5.79.2554,094
86213.5.80.0/20213.5.80.1 to 213.5.95.254213.5.95.2554,094
87213.5.96.0/20213.5.96.1 to 213.5.111.254213.5.111.2554,094
88213.5.112.0/20213.5.112.1 to 213.5.127.254213.5.127.2554,094
89213.5.128.0/20213.5.128.1 to 213.5.143.254213.5.143.2554,094
90213.5.144.0/20213.5.144.1 to 213.5.159.254213.5.159.2554,094
91213.5.160.0/20213.5.160.1 to 213.5.175.254213.5.175.2554,094
92213.5.176.0/20213.5.176.1 to 213.5.191.254213.5.191.2554,094
93213.5.192.0/20213.5.192.1 to 213.5.207.254213.5.207.2554,094
94213.5.208.0/20213.5.208.1 to 213.5.223.254213.5.223.2554,094
95213.5.224.0/20213.5.224.1 to 213.5.239.254213.5.239.2554,094
96213.5.240.0/20213.5.240.1 to 213.5.255.254213.5.255.2554,094
97213.6.0.0/20213.6.0.1 to 213.6.15.254213.6.15.2554,094
98213.6.16.0/20213.6.16.1 to 213.6.31.254213.6.31.2554,094
99213.6.32.0/20213.6.32.1 to 213.6.47.254213.6.47.2554,094
100213.6.48.0/20213.6.48.1 to 213.6.63.254213.6.63.2554,094
101213.6.64.0/20213.6.64.1 to 213.6.79.254213.6.79.2554,094
102213.6.80.0/20213.6.80.1 to 213.6.95.254213.6.95.2554,094
103213.6.96.0/20213.6.96.1 to 213.6.111.254213.6.111.2554,094
104213.6.112.0/20213.6.112.1 to 213.6.127.254213.6.127.2554,094
105213.6.128.0/20213.6.128.1 to 213.6.143.254213.6.143.2554,094
106213.6.144.0/20213.6.144.1 to 213.6.159.254213.6.159.2554,094
107213.6.160.0/20213.6.160.1 to 213.6.175.254213.6.175.2554,094
108213.6.176.0/20213.6.176.1 to 213.6.191.254213.6.191.2554,094
109213.6.192.0/20213.6.192.1 to 213.6.207.254213.6.207.2554,094
110213.6.208.0/20213.6.208.1 to 213.6.223.254213.6.223.2554,094
111213.6.224.0/20213.6.224.1 to 213.6.239.254213.6.239.2554,094
112213.6.240.0/20213.6.240.1 to 213.6.255.254213.6.255.2554,094
113213.7.0.0/20213.7.0.1 to 213.7.15.254213.7.15.2554,094
114213.7.16.0/20213.7.16.1 to 213.7.31.254213.7.31.2554,094
115213.7.32.0/20213.7.32.1 to 213.7.47.254213.7.47.2554,094
116213.7.48.0/20213.7.48.1 to 213.7.63.254213.7.63.2554,094
117213.7.64.0/20213.7.64.1 to 213.7.79.254213.7.79.2554,094
118213.7.80.0/20213.7.80.1 to 213.7.95.254213.7.95.2554,094
119213.7.96.0/20213.7.96.1 to 213.7.111.254213.7.111.2554,094
120213.7.112.0/20213.7.112.1 to 213.7.127.254213.7.127.2554,094
121213.7.128.0/20213.7.128.1 to 213.7.143.254213.7.143.2554,094
122213.7.144.0/20213.7.144.1 to 213.7.159.254213.7.159.2554,094
123213.7.160.0/20213.7.160.1 to 213.7.175.254213.7.175.2554,094
124213.7.176.0/20213.7.176.1 to 213.7.191.254213.7.191.2554,094
125213.7.192.0/20213.7.192.1 to 213.7.207.254213.7.207.2554,094
126213.7.208.0/20213.7.208.1 to 213.7.223.254213.7.223.2554,094
127213.7.224.0/20213.7.224.1 to 213.7.239.254213.7.239.2554,094
128213.7.240.0/20213.7.240.1 to 213.7.255.254213.7.255.2554,094

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.