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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.

Network136.2.0.0/15
Usable hosts131,070
Subnet mask255.254.0.0
Addresses131,072
Network address
136.2.0.0
Broadcast address
136.3.255.255
First usable
136.2.0.1
Last usable
136.3.255.254
Usable hosts
131,070 (131,072 less the network and broadcast addresses)
Subnet mask
255.254.0.0
Wildcard mask
0.1.255.255 (Cisco ACLs, OSPF)
Prefix length
/15
Type
Public public
Old class
B (default /16)
As numbers
Hex 88020000 · Integer 2281832448 to 2281963519
Reverse DNS zones
2.136.in-addr.arpa
3.136.in-addr.arpa
/15 is not on a 8-bit boundary, so it takes 2 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10001000.00000010.00000000.00000000136.2.0.0
Subnet mask11111111.11111110.00000000.00000000255.254.0.0
Network10001000.00000010.00000000.00000000136.2.0.0
Broadcast10001000.00000011.11111111.11111111136.3.255.255
Split into smaller subnets/22
/16 (2)/17 (4)/18 (8)/19 (16)/20 (32)/21 (64)/22 (128)/23 (256)/24 (512)/25 (1,024)/26 (2,048)/27 (4,096)

136.2.0.0/15 makes 128 subnets of /22.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1136.2.0.0/22136.2.0.1 to 136.2.3.254136.2.3.2551,022
2136.2.4.0/22136.2.4.1 to 136.2.7.254136.2.7.2551,022
3136.2.8.0/22136.2.8.1 to 136.2.11.254136.2.11.2551,022
4136.2.12.0/22136.2.12.1 to 136.2.15.254136.2.15.2551,022
5136.2.16.0/22136.2.16.1 to 136.2.19.254136.2.19.2551,022
6136.2.20.0/22136.2.20.1 to 136.2.23.254136.2.23.2551,022
7136.2.24.0/22136.2.24.1 to 136.2.27.254136.2.27.2551,022
8136.2.28.0/22136.2.28.1 to 136.2.31.254136.2.31.2551,022
9136.2.32.0/22136.2.32.1 to 136.2.35.254136.2.35.2551,022
10136.2.36.0/22136.2.36.1 to 136.2.39.254136.2.39.2551,022
11136.2.40.0/22136.2.40.1 to 136.2.43.254136.2.43.2551,022
12136.2.44.0/22136.2.44.1 to 136.2.47.254136.2.47.2551,022
13136.2.48.0/22136.2.48.1 to 136.2.51.254136.2.51.2551,022
14136.2.52.0/22136.2.52.1 to 136.2.55.254136.2.55.2551,022
15136.2.56.0/22136.2.56.1 to 136.2.59.254136.2.59.2551,022
16136.2.60.0/22136.2.60.1 to 136.2.63.254136.2.63.2551,022
17136.2.64.0/22136.2.64.1 to 136.2.67.254136.2.67.2551,022
18136.2.68.0/22136.2.68.1 to 136.2.71.254136.2.71.2551,022
19136.2.72.0/22136.2.72.1 to 136.2.75.254136.2.75.2551,022
20136.2.76.0/22136.2.76.1 to 136.2.79.254136.2.79.2551,022
21136.2.80.0/22136.2.80.1 to 136.2.83.254136.2.83.2551,022
22136.2.84.0/22136.2.84.1 to 136.2.87.254136.2.87.2551,022
23136.2.88.0/22136.2.88.1 to 136.2.91.254136.2.91.2551,022
24136.2.92.0/22136.2.92.1 to 136.2.95.254136.2.95.2551,022
25136.2.96.0/22136.2.96.1 to 136.2.99.254136.2.99.2551,022
26136.2.100.0/22136.2.100.1 to 136.2.103.254136.2.103.2551,022
27136.2.104.0/22136.2.104.1 to 136.2.107.254136.2.107.2551,022
28136.2.108.0/22136.2.108.1 to 136.2.111.254136.2.111.2551,022
29136.2.112.0/22136.2.112.1 to 136.2.115.254136.2.115.2551,022
30136.2.116.0/22136.2.116.1 to 136.2.119.254136.2.119.2551,022
31136.2.120.0/22136.2.120.1 to 136.2.123.254136.2.123.2551,022
32136.2.124.0/22136.2.124.1 to 136.2.127.254136.2.127.2551,022
33136.2.128.0/22136.2.128.1 to 136.2.131.254136.2.131.2551,022
34136.2.132.0/22136.2.132.1 to 136.2.135.254136.2.135.2551,022
35136.2.136.0/22136.2.136.1 to 136.2.139.254136.2.139.2551,022
36136.2.140.0/22136.2.140.1 to 136.2.143.254136.2.143.2551,022
37136.2.144.0/22136.2.144.1 to 136.2.147.254136.2.147.2551,022
38136.2.148.0/22136.2.148.1 to 136.2.151.254136.2.151.2551,022
39136.2.152.0/22136.2.152.1 to 136.2.155.254136.2.155.2551,022
40136.2.156.0/22136.2.156.1 to 136.2.159.254136.2.159.2551,022
41136.2.160.0/22136.2.160.1 to 136.2.163.254136.2.163.2551,022
42136.2.164.0/22136.2.164.1 to 136.2.167.254136.2.167.2551,022
43136.2.168.0/22136.2.168.1 to 136.2.171.254136.2.171.2551,022
44136.2.172.0/22136.2.172.1 to 136.2.175.254136.2.175.2551,022
45136.2.176.0/22136.2.176.1 to 136.2.179.254136.2.179.2551,022
46136.2.180.0/22136.2.180.1 to 136.2.183.254136.2.183.2551,022
47136.2.184.0/22136.2.184.1 to 136.2.187.254136.2.187.2551,022
48136.2.188.0/22136.2.188.1 to 136.2.191.254136.2.191.2551,022
49136.2.192.0/22136.2.192.1 to 136.2.195.254136.2.195.2551,022
50136.2.196.0/22136.2.196.1 to 136.2.199.254136.2.199.2551,022
51136.2.200.0/22136.2.200.1 to 136.2.203.254136.2.203.2551,022
52136.2.204.0/22136.2.204.1 to 136.2.207.254136.2.207.2551,022
53136.2.208.0/22136.2.208.1 to 136.2.211.254136.2.211.2551,022
54136.2.212.0/22136.2.212.1 to 136.2.215.254136.2.215.2551,022
55136.2.216.0/22136.2.216.1 to 136.2.219.254136.2.219.2551,022
56136.2.220.0/22136.2.220.1 to 136.2.223.254136.2.223.2551,022
57136.2.224.0/22136.2.224.1 to 136.2.227.254136.2.227.2551,022
58136.2.228.0/22136.2.228.1 to 136.2.231.254136.2.231.2551,022
59136.2.232.0/22136.2.232.1 to 136.2.235.254136.2.235.2551,022
60136.2.236.0/22136.2.236.1 to 136.2.239.254136.2.239.2551,022
61136.2.240.0/22136.2.240.1 to 136.2.243.254136.2.243.2551,022
62136.2.244.0/22136.2.244.1 to 136.2.247.254136.2.247.2551,022
63136.2.248.0/22136.2.248.1 to 136.2.251.254136.2.251.2551,022
64136.2.252.0/22136.2.252.1 to 136.2.255.254136.2.255.2551,022
65136.3.0.0/22136.3.0.1 to 136.3.3.254136.3.3.2551,022
66136.3.4.0/22136.3.4.1 to 136.3.7.254136.3.7.2551,022
67136.3.8.0/22136.3.8.1 to 136.3.11.254136.3.11.2551,022
68136.3.12.0/22136.3.12.1 to 136.3.15.254136.3.15.2551,022
69136.3.16.0/22136.3.16.1 to 136.3.19.254136.3.19.2551,022
70136.3.20.0/22136.3.20.1 to 136.3.23.254136.3.23.2551,022
71136.3.24.0/22136.3.24.1 to 136.3.27.254136.3.27.2551,022
72136.3.28.0/22136.3.28.1 to 136.3.31.254136.3.31.2551,022
73136.3.32.0/22136.3.32.1 to 136.3.35.254136.3.35.2551,022
74136.3.36.0/22136.3.36.1 to 136.3.39.254136.3.39.2551,022
75136.3.40.0/22136.3.40.1 to 136.3.43.254136.3.43.2551,022
76136.3.44.0/22136.3.44.1 to 136.3.47.254136.3.47.2551,022
77136.3.48.0/22136.3.48.1 to 136.3.51.254136.3.51.2551,022
78136.3.52.0/22136.3.52.1 to 136.3.55.254136.3.55.2551,022
79136.3.56.0/22136.3.56.1 to 136.3.59.254136.3.59.2551,022
80136.3.60.0/22136.3.60.1 to 136.3.63.254136.3.63.2551,022
81136.3.64.0/22136.3.64.1 to 136.3.67.254136.3.67.2551,022
82136.3.68.0/22136.3.68.1 to 136.3.71.254136.3.71.2551,022
83136.3.72.0/22136.3.72.1 to 136.3.75.254136.3.75.2551,022
84136.3.76.0/22136.3.76.1 to 136.3.79.254136.3.79.2551,022
85136.3.80.0/22136.3.80.1 to 136.3.83.254136.3.83.2551,022
86136.3.84.0/22136.3.84.1 to 136.3.87.254136.3.87.2551,022
87136.3.88.0/22136.3.88.1 to 136.3.91.254136.3.91.2551,022
88136.3.92.0/22136.3.92.1 to 136.3.95.254136.3.95.2551,022
89136.3.96.0/22136.3.96.1 to 136.3.99.254136.3.99.2551,022
90136.3.100.0/22136.3.100.1 to 136.3.103.254136.3.103.2551,022
91136.3.104.0/22136.3.104.1 to 136.3.107.254136.3.107.2551,022
92136.3.108.0/22136.3.108.1 to 136.3.111.254136.3.111.2551,022
93136.3.112.0/22136.3.112.1 to 136.3.115.254136.3.115.2551,022
94136.3.116.0/22136.3.116.1 to 136.3.119.254136.3.119.2551,022
95136.3.120.0/22136.3.120.1 to 136.3.123.254136.3.123.2551,022
96136.3.124.0/22136.3.124.1 to 136.3.127.254136.3.127.2551,022
97136.3.128.0/22136.3.128.1 to 136.3.131.254136.3.131.2551,022
98136.3.132.0/22136.3.132.1 to 136.3.135.254136.3.135.2551,022
99136.3.136.0/22136.3.136.1 to 136.3.139.254136.3.139.2551,022
100136.3.140.0/22136.3.140.1 to 136.3.143.254136.3.143.2551,022
101136.3.144.0/22136.3.144.1 to 136.3.147.254136.3.147.2551,022
102136.3.148.0/22136.3.148.1 to 136.3.151.254136.3.151.2551,022
103136.3.152.0/22136.3.152.1 to 136.3.155.254136.3.155.2551,022
104136.3.156.0/22136.3.156.1 to 136.3.159.254136.3.159.2551,022
105136.3.160.0/22136.3.160.1 to 136.3.163.254136.3.163.2551,022
106136.3.164.0/22136.3.164.1 to 136.3.167.254136.3.167.2551,022
107136.3.168.0/22136.3.168.1 to 136.3.171.254136.3.171.2551,022
108136.3.172.0/22136.3.172.1 to 136.3.175.254136.3.175.2551,022
109136.3.176.0/22136.3.176.1 to 136.3.179.254136.3.179.2551,022
110136.3.180.0/22136.3.180.1 to 136.3.183.254136.3.183.2551,022
111136.3.184.0/22136.3.184.1 to 136.3.187.254136.3.187.2551,022
112136.3.188.0/22136.3.188.1 to 136.3.191.254136.3.191.2551,022
113136.3.192.0/22136.3.192.1 to 136.3.195.254136.3.195.2551,022
114136.3.196.0/22136.3.196.1 to 136.3.199.254136.3.199.2551,022
115136.3.200.0/22136.3.200.1 to 136.3.203.254136.3.203.2551,022
116136.3.204.0/22136.3.204.1 to 136.3.207.254136.3.207.2551,022
117136.3.208.0/22136.3.208.1 to 136.3.211.254136.3.211.2551,022
118136.3.212.0/22136.3.212.1 to 136.3.215.254136.3.215.2551,022
119136.3.216.0/22136.3.216.1 to 136.3.219.254136.3.219.2551,022
120136.3.220.0/22136.3.220.1 to 136.3.223.254136.3.223.2551,022
121136.3.224.0/22136.3.224.1 to 136.3.227.254136.3.227.2551,022
122136.3.228.0/22136.3.228.1 to 136.3.231.254136.3.231.2551,022
123136.3.232.0/22136.3.232.1 to 136.3.235.254136.3.235.2551,022
124136.3.236.0/22136.3.236.1 to 136.3.239.254136.3.239.2551,022
125136.3.240.0/22136.3.240.1 to 136.3.243.254136.3.243.2551,022
126136.3.244.0/22136.3.244.1 to 136.3.247.254136.3.247.2551,022
127136.3.248.0/22136.3.248.1 to 136.3.251.254136.3.251.2551,022
128136.3.252.0/22136.3.252.1 to 136.3.255.254136.3.255.2551,022

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.