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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.

Network102.136.0.0/13
Usable hosts524,286
Subnet mask255.248.0.0
Addresses524,288
Network address
102.136.0.0
Broadcast address
102.143.255.255
First usable
102.136.0.1
Last usable
102.143.255.254
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 66880000 · Integer 1720188928 to 1720713215
Reverse DNS zones
136.102.in-addr.arpa
137.102.in-addr.arpa
138.102.in-addr.arpa
139.102.in-addr.arpa
140.102.in-addr.arpa
141.102.in-addr.arpa
142.102.in-addr.arpa
143.102.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
Address01100110.10001000.00000000.00000000102.136.0.0
Subnet mask11111111.11111000.00000000.00000000255.248.0.0
Network01100110.10001000.00000000.00000000102.136.0.0
Broadcast01100110.10001111.11111111.11111111102.143.255.255
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)

102.136.0.0/13 makes 128 subnets of /20.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1102.136.0.0/20102.136.0.1 to 102.136.15.254102.136.15.2554,094
2102.136.16.0/20102.136.16.1 to 102.136.31.254102.136.31.2554,094
3102.136.32.0/20102.136.32.1 to 102.136.47.254102.136.47.2554,094
4102.136.48.0/20102.136.48.1 to 102.136.63.254102.136.63.2554,094
5102.136.64.0/20102.136.64.1 to 102.136.79.254102.136.79.2554,094
6102.136.80.0/20102.136.80.1 to 102.136.95.254102.136.95.2554,094
7102.136.96.0/20102.136.96.1 to 102.136.111.254102.136.111.2554,094
8102.136.112.0/20102.136.112.1 to 102.136.127.254102.136.127.2554,094
9102.136.128.0/20102.136.128.1 to 102.136.143.254102.136.143.2554,094
10102.136.144.0/20102.136.144.1 to 102.136.159.254102.136.159.2554,094
11102.136.160.0/20102.136.160.1 to 102.136.175.254102.136.175.2554,094
12102.136.176.0/20102.136.176.1 to 102.136.191.254102.136.191.2554,094
13102.136.192.0/20102.136.192.1 to 102.136.207.254102.136.207.2554,094
14102.136.208.0/20102.136.208.1 to 102.136.223.254102.136.223.2554,094
15102.136.224.0/20102.136.224.1 to 102.136.239.254102.136.239.2554,094
16102.136.240.0/20102.136.240.1 to 102.136.255.254102.136.255.2554,094
17102.137.0.0/20102.137.0.1 to 102.137.15.254102.137.15.2554,094
18102.137.16.0/20102.137.16.1 to 102.137.31.254102.137.31.2554,094
19102.137.32.0/20102.137.32.1 to 102.137.47.254102.137.47.2554,094
20102.137.48.0/20102.137.48.1 to 102.137.63.254102.137.63.2554,094
21102.137.64.0/20102.137.64.1 to 102.137.79.254102.137.79.2554,094
22102.137.80.0/20102.137.80.1 to 102.137.95.254102.137.95.2554,094
23102.137.96.0/20102.137.96.1 to 102.137.111.254102.137.111.2554,094
24102.137.112.0/20102.137.112.1 to 102.137.127.254102.137.127.2554,094
25102.137.128.0/20102.137.128.1 to 102.137.143.254102.137.143.2554,094
26102.137.144.0/20102.137.144.1 to 102.137.159.254102.137.159.2554,094
27102.137.160.0/20102.137.160.1 to 102.137.175.254102.137.175.2554,094
28102.137.176.0/20102.137.176.1 to 102.137.191.254102.137.191.2554,094
29102.137.192.0/20102.137.192.1 to 102.137.207.254102.137.207.2554,094
30102.137.208.0/20102.137.208.1 to 102.137.223.254102.137.223.2554,094
31102.137.224.0/20102.137.224.1 to 102.137.239.254102.137.239.2554,094
32102.137.240.0/20102.137.240.1 to 102.137.255.254102.137.255.2554,094
33102.138.0.0/20102.138.0.1 to 102.138.15.254102.138.15.2554,094
34102.138.16.0/20102.138.16.1 to 102.138.31.254102.138.31.2554,094
35102.138.32.0/20102.138.32.1 to 102.138.47.254102.138.47.2554,094
36102.138.48.0/20102.138.48.1 to 102.138.63.254102.138.63.2554,094
37102.138.64.0/20102.138.64.1 to 102.138.79.254102.138.79.2554,094
38102.138.80.0/20102.138.80.1 to 102.138.95.254102.138.95.2554,094
39102.138.96.0/20102.138.96.1 to 102.138.111.254102.138.111.2554,094
40102.138.112.0/20102.138.112.1 to 102.138.127.254102.138.127.2554,094
41102.138.128.0/20102.138.128.1 to 102.138.143.254102.138.143.2554,094
42102.138.144.0/20102.138.144.1 to 102.138.159.254102.138.159.2554,094
43102.138.160.0/20102.138.160.1 to 102.138.175.254102.138.175.2554,094
44102.138.176.0/20102.138.176.1 to 102.138.191.254102.138.191.2554,094
45102.138.192.0/20102.138.192.1 to 102.138.207.254102.138.207.2554,094
46102.138.208.0/20102.138.208.1 to 102.138.223.254102.138.223.2554,094
47102.138.224.0/20102.138.224.1 to 102.138.239.254102.138.239.2554,094
48102.138.240.0/20102.138.240.1 to 102.138.255.254102.138.255.2554,094
49102.139.0.0/20102.139.0.1 to 102.139.15.254102.139.15.2554,094
50102.139.16.0/20102.139.16.1 to 102.139.31.254102.139.31.2554,094
51102.139.32.0/20102.139.32.1 to 102.139.47.254102.139.47.2554,094
52102.139.48.0/20102.139.48.1 to 102.139.63.254102.139.63.2554,094
53102.139.64.0/20102.139.64.1 to 102.139.79.254102.139.79.2554,094
54102.139.80.0/20102.139.80.1 to 102.139.95.254102.139.95.2554,094
55102.139.96.0/20102.139.96.1 to 102.139.111.254102.139.111.2554,094
56102.139.112.0/20102.139.112.1 to 102.139.127.254102.139.127.2554,094
57102.139.128.0/20102.139.128.1 to 102.139.143.254102.139.143.2554,094
58102.139.144.0/20102.139.144.1 to 102.139.159.254102.139.159.2554,094
59102.139.160.0/20102.139.160.1 to 102.139.175.254102.139.175.2554,094
60102.139.176.0/20102.139.176.1 to 102.139.191.254102.139.191.2554,094
61102.139.192.0/20102.139.192.1 to 102.139.207.254102.139.207.2554,094
62102.139.208.0/20102.139.208.1 to 102.139.223.254102.139.223.2554,094
63102.139.224.0/20102.139.224.1 to 102.139.239.254102.139.239.2554,094
64102.139.240.0/20102.139.240.1 to 102.139.255.254102.139.255.2554,094
65102.140.0.0/20102.140.0.1 to 102.140.15.254102.140.15.2554,094
66102.140.16.0/20102.140.16.1 to 102.140.31.254102.140.31.2554,094
67102.140.32.0/20102.140.32.1 to 102.140.47.254102.140.47.2554,094
68102.140.48.0/20102.140.48.1 to 102.140.63.254102.140.63.2554,094
69102.140.64.0/20102.140.64.1 to 102.140.79.254102.140.79.2554,094
70102.140.80.0/20102.140.80.1 to 102.140.95.254102.140.95.2554,094
71102.140.96.0/20102.140.96.1 to 102.140.111.254102.140.111.2554,094
72102.140.112.0/20102.140.112.1 to 102.140.127.254102.140.127.2554,094
73102.140.128.0/20102.140.128.1 to 102.140.143.254102.140.143.2554,094
74102.140.144.0/20102.140.144.1 to 102.140.159.254102.140.159.2554,094
75102.140.160.0/20102.140.160.1 to 102.140.175.254102.140.175.2554,094
76102.140.176.0/20102.140.176.1 to 102.140.191.254102.140.191.2554,094
77102.140.192.0/20102.140.192.1 to 102.140.207.254102.140.207.2554,094
78102.140.208.0/20102.140.208.1 to 102.140.223.254102.140.223.2554,094
79102.140.224.0/20102.140.224.1 to 102.140.239.254102.140.239.2554,094
80102.140.240.0/20102.140.240.1 to 102.140.255.254102.140.255.2554,094
81102.141.0.0/20102.141.0.1 to 102.141.15.254102.141.15.2554,094
82102.141.16.0/20102.141.16.1 to 102.141.31.254102.141.31.2554,094
83102.141.32.0/20102.141.32.1 to 102.141.47.254102.141.47.2554,094
84102.141.48.0/20102.141.48.1 to 102.141.63.254102.141.63.2554,094
85102.141.64.0/20102.141.64.1 to 102.141.79.254102.141.79.2554,094
86102.141.80.0/20102.141.80.1 to 102.141.95.254102.141.95.2554,094
87102.141.96.0/20102.141.96.1 to 102.141.111.254102.141.111.2554,094
88102.141.112.0/20102.141.112.1 to 102.141.127.254102.141.127.2554,094
89102.141.128.0/20102.141.128.1 to 102.141.143.254102.141.143.2554,094
90102.141.144.0/20102.141.144.1 to 102.141.159.254102.141.159.2554,094
91102.141.160.0/20102.141.160.1 to 102.141.175.254102.141.175.2554,094
92102.141.176.0/20102.141.176.1 to 102.141.191.254102.141.191.2554,094
93102.141.192.0/20102.141.192.1 to 102.141.207.254102.141.207.2554,094
94102.141.208.0/20102.141.208.1 to 102.141.223.254102.141.223.2554,094
95102.141.224.0/20102.141.224.1 to 102.141.239.254102.141.239.2554,094
96102.141.240.0/20102.141.240.1 to 102.141.255.254102.141.255.2554,094
97102.142.0.0/20102.142.0.1 to 102.142.15.254102.142.15.2554,094
98102.142.16.0/20102.142.16.1 to 102.142.31.254102.142.31.2554,094
99102.142.32.0/20102.142.32.1 to 102.142.47.254102.142.47.2554,094
100102.142.48.0/20102.142.48.1 to 102.142.63.254102.142.63.2554,094
101102.142.64.0/20102.142.64.1 to 102.142.79.254102.142.79.2554,094
102102.142.80.0/20102.142.80.1 to 102.142.95.254102.142.95.2554,094
103102.142.96.0/20102.142.96.1 to 102.142.111.254102.142.111.2554,094
104102.142.112.0/20102.142.112.1 to 102.142.127.254102.142.127.2554,094
105102.142.128.0/20102.142.128.1 to 102.142.143.254102.142.143.2554,094
106102.142.144.0/20102.142.144.1 to 102.142.159.254102.142.159.2554,094
107102.142.160.0/20102.142.160.1 to 102.142.175.254102.142.175.2554,094
108102.142.176.0/20102.142.176.1 to 102.142.191.254102.142.191.2554,094
109102.142.192.0/20102.142.192.1 to 102.142.207.254102.142.207.2554,094
110102.142.208.0/20102.142.208.1 to 102.142.223.254102.142.223.2554,094
111102.142.224.0/20102.142.224.1 to 102.142.239.254102.142.239.2554,094
112102.142.240.0/20102.142.240.1 to 102.142.255.254102.142.255.2554,094
113102.143.0.0/20102.143.0.1 to 102.143.15.254102.143.15.2554,094
114102.143.16.0/20102.143.16.1 to 102.143.31.254102.143.31.2554,094
115102.143.32.0/20102.143.32.1 to 102.143.47.254102.143.47.2554,094
116102.143.48.0/20102.143.48.1 to 102.143.63.254102.143.63.2554,094
117102.143.64.0/20102.143.64.1 to 102.143.79.254102.143.79.2554,094
118102.143.80.0/20102.143.80.1 to 102.143.95.254102.143.95.2554,094
119102.143.96.0/20102.143.96.1 to 102.143.111.254102.143.111.2554,094
120102.143.112.0/20102.143.112.1 to 102.143.127.254102.143.127.2554,094
121102.143.128.0/20102.143.128.1 to 102.143.143.254102.143.143.2554,094
122102.143.144.0/20102.143.144.1 to 102.143.159.254102.143.159.2554,094
123102.143.160.0/20102.143.160.1 to 102.143.175.254102.143.175.2554,094
124102.143.176.0/20102.143.176.1 to 102.143.191.254102.143.191.2554,094
125102.143.192.0/20102.143.192.1 to 102.143.207.254102.143.207.2554,094
126102.143.208.0/20102.143.208.1 to 102.143.223.254102.143.223.2554,094
127102.143.224.0/20102.143.224.1 to 102.143.239.254102.143.239.2554,094
128102.143.240.0/20102.143.240.1 to 102.143.255.254102.143.255.2554,094

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.