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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.

Network136.0.0.0/7
Usable hosts33,554,430
Subnet mask254.0.0.0
Addresses33,554,432
Network address
136.0.0.0
Broadcast address
137.255.255.255
First usable
136.0.0.1
Last usable
137.255.255.254
Usable hosts
33,554,430 (33,554,432 less the network and broadcast addresses)
Subnet mask
254.0.0.0
Wildcard mask
1.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/7
Type
Public public
Old class
B (default /16)
As numbers
Hex 88000000 · Integer 2281701376 to 2315255807
Reverse DNS zones
136.in-addr.arpa
137.in-addr.arpa
/7 is not on a 8-bit boundary, so it takes 2 /8 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10001000.00000000.00000000.00000000136.0.0.0
Subnet mask11111110.00000000.00000000.00000000254.0.0.0
Network10001000.00000000.00000000.00000000136.0.0.0
Broadcast10001001.11111111.11111111.11111111137.255.255.255
Split into smaller subnets/14
/8 (2)/9 (4)/10 (8)/11 (16)/12 (32)/13 (64)/14 (128)/15 (256)/16 (512)/17 (1,024)/18 (2,048)/19 (4,096)

136.0.0.0/7 makes 128 subnets of /14.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1136.0.0.0/14136.0.0.1 to 136.3.255.254136.3.255.255262,142
2136.4.0.0/14136.4.0.1 to 136.7.255.254136.7.255.255262,142
3136.8.0.0/14136.8.0.1 to 136.11.255.254136.11.255.255262,142
4136.12.0.0/14136.12.0.1 to 136.15.255.254136.15.255.255262,142
5136.16.0.0/14136.16.0.1 to 136.19.255.254136.19.255.255262,142
6136.20.0.0/14136.20.0.1 to 136.23.255.254136.23.255.255262,142
7136.24.0.0/14136.24.0.1 to 136.27.255.254136.27.255.255262,142
8136.28.0.0/14136.28.0.1 to 136.31.255.254136.31.255.255262,142
9136.32.0.0/14136.32.0.1 to 136.35.255.254136.35.255.255262,142
10136.36.0.0/14136.36.0.1 to 136.39.255.254136.39.255.255262,142
11136.40.0.0/14136.40.0.1 to 136.43.255.254136.43.255.255262,142
12136.44.0.0/14136.44.0.1 to 136.47.255.254136.47.255.255262,142
13136.48.0.0/14136.48.0.1 to 136.51.255.254136.51.255.255262,142
14136.52.0.0/14136.52.0.1 to 136.55.255.254136.55.255.255262,142
15136.56.0.0/14136.56.0.1 to 136.59.255.254136.59.255.255262,142
16136.60.0.0/14136.60.0.1 to 136.63.255.254136.63.255.255262,142
17136.64.0.0/14136.64.0.1 to 136.67.255.254136.67.255.255262,142
18136.68.0.0/14136.68.0.1 to 136.71.255.254136.71.255.255262,142
19136.72.0.0/14136.72.0.1 to 136.75.255.254136.75.255.255262,142
20136.76.0.0/14136.76.0.1 to 136.79.255.254136.79.255.255262,142
21136.80.0.0/14136.80.0.1 to 136.83.255.254136.83.255.255262,142
22136.84.0.0/14136.84.0.1 to 136.87.255.254136.87.255.255262,142
23136.88.0.0/14136.88.0.1 to 136.91.255.254136.91.255.255262,142
24136.92.0.0/14136.92.0.1 to 136.95.255.254136.95.255.255262,142
25136.96.0.0/14136.96.0.1 to 136.99.255.254136.99.255.255262,142
26136.100.0.0/14136.100.0.1 to 136.103.255.254136.103.255.255262,142
27136.104.0.0/14136.104.0.1 to 136.107.255.254136.107.255.255262,142
28136.108.0.0/14136.108.0.1 to 136.111.255.254136.111.255.255262,142
29136.112.0.0/14136.112.0.1 to 136.115.255.254136.115.255.255262,142
30136.116.0.0/14136.116.0.1 to 136.119.255.254136.119.255.255262,142
31136.120.0.0/14136.120.0.1 to 136.123.255.254136.123.255.255262,142
32136.124.0.0/14136.124.0.1 to 136.127.255.254136.127.255.255262,142
33136.128.0.0/14136.128.0.1 to 136.131.255.254136.131.255.255262,142
34136.132.0.0/14136.132.0.1 to 136.135.255.254136.135.255.255262,142
35136.136.0.0/14136.136.0.1 to 136.139.255.254136.139.255.255262,142
36136.140.0.0/14136.140.0.1 to 136.143.255.254136.143.255.255262,142
37136.144.0.0/14136.144.0.1 to 136.147.255.254136.147.255.255262,142
38136.148.0.0/14136.148.0.1 to 136.151.255.254136.151.255.255262,142
39136.152.0.0/14136.152.0.1 to 136.155.255.254136.155.255.255262,142
40136.156.0.0/14136.156.0.1 to 136.159.255.254136.159.255.255262,142
41136.160.0.0/14136.160.0.1 to 136.163.255.254136.163.255.255262,142
42136.164.0.0/14136.164.0.1 to 136.167.255.254136.167.255.255262,142
43136.168.0.0/14136.168.0.1 to 136.171.255.254136.171.255.255262,142
44136.172.0.0/14136.172.0.1 to 136.175.255.254136.175.255.255262,142
45136.176.0.0/14136.176.0.1 to 136.179.255.254136.179.255.255262,142
46136.180.0.0/14136.180.0.1 to 136.183.255.254136.183.255.255262,142
47136.184.0.0/14136.184.0.1 to 136.187.255.254136.187.255.255262,142
48136.188.0.0/14136.188.0.1 to 136.191.255.254136.191.255.255262,142
49136.192.0.0/14136.192.0.1 to 136.195.255.254136.195.255.255262,142
50136.196.0.0/14136.196.0.1 to 136.199.255.254136.199.255.255262,142
51136.200.0.0/14136.200.0.1 to 136.203.255.254136.203.255.255262,142
52136.204.0.0/14136.204.0.1 to 136.207.255.254136.207.255.255262,142
53136.208.0.0/14136.208.0.1 to 136.211.255.254136.211.255.255262,142
54136.212.0.0/14136.212.0.1 to 136.215.255.254136.215.255.255262,142
55136.216.0.0/14136.216.0.1 to 136.219.255.254136.219.255.255262,142
56136.220.0.0/14136.220.0.1 to 136.223.255.254136.223.255.255262,142
57136.224.0.0/14136.224.0.1 to 136.227.255.254136.227.255.255262,142
58136.228.0.0/14136.228.0.1 to 136.231.255.254136.231.255.255262,142
59136.232.0.0/14136.232.0.1 to 136.235.255.254136.235.255.255262,142
60136.236.0.0/14136.236.0.1 to 136.239.255.254136.239.255.255262,142
61136.240.0.0/14136.240.0.1 to 136.243.255.254136.243.255.255262,142
62136.244.0.0/14136.244.0.1 to 136.247.255.254136.247.255.255262,142
63136.248.0.0/14136.248.0.1 to 136.251.255.254136.251.255.255262,142
64136.252.0.0/14136.252.0.1 to 136.255.255.254136.255.255.255262,142
65137.0.0.0/14137.0.0.1 to 137.3.255.254137.3.255.255262,142
66137.4.0.0/14137.4.0.1 to 137.7.255.254137.7.255.255262,142
67137.8.0.0/14137.8.0.1 to 137.11.255.254137.11.255.255262,142
68137.12.0.0/14137.12.0.1 to 137.15.255.254137.15.255.255262,142
69137.16.0.0/14137.16.0.1 to 137.19.255.254137.19.255.255262,142
70137.20.0.0/14137.20.0.1 to 137.23.255.254137.23.255.255262,142
71137.24.0.0/14137.24.0.1 to 137.27.255.254137.27.255.255262,142
72137.28.0.0/14137.28.0.1 to 137.31.255.254137.31.255.255262,142
73137.32.0.0/14137.32.0.1 to 137.35.255.254137.35.255.255262,142
74137.36.0.0/14137.36.0.1 to 137.39.255.254137.39.255.255262,142
75137.40.0.0/14137.40.0.1 to 137.43.255.254137.43.255.255262,142
76137.44.0.0/14137.44.0.1 to 137.47.255.254137.47.255.255262,142
77137.48.0.0/14137.48.0.1 to 137.51.255.254137.51.255.255262,142
78137.52.0.0/14137.52.0.1 to 137.55.255.254137.55.255.255262,142
79137.56.0.0/14137.56.0.1 to 137.59.255.254137.59.255.255262,142
80137.60.0.0/14137.60.0.1 to 137.63.255.254137.63.255.255262,142
81137.64.0.0/14137.64.0.1 to 137.67.255.254137.67.255.255262,142
82137.68.0.0/14137.68.0.1 to 137.71.255.254137.71.255.255262,142
83137.72.0.0/14137.72.0.1 to 137.75.255.254137.75.255.255262,142
84137.76.0.0/14137.76.0.1 to 137.79.255.254137.79.255.255262,142
85137.80.0.0/14137.80.0.1 to 137.83.255.254137.83.255.255262,142
86137.84.0.0/14137.84.0.1 to 137.87.255.254137.87.255.255262,142
87137.88.0.0/14137.88.0.1 to 137.91.255.254137.91.255.255262,142
88137.92.0.0/14137.92.0.1 to 137.95.255.254137.95.255.255262,142
89137.96.0.0/14137.96.0.1 to 137.99.255.254137.99.255.255262,142
90137.100.0.0/14137.100.0.1 to 137.103.255.254137.103.255.255262,142
91137.104.0.0/14137.104.0.1 to 137.107.255.254137.107.255.255262,142
92137.108.0.0/14137.108.0.1 to 137.111.255.254137.111.255.255262,142
93137.112.0.0/14137.112.0.1 to 137.115.255.254137.115.255.255262,142
94137.116.0.0/14137.116.0.1 to 137.119.255.254137.119.255.255262,142
95137.120.0.0/14137.120.0.1 to 137.123.255.254137.123.255.255262,142
96137.124.0.0/14137.124.0.1 to 137.127.255.254137.127.255.255262,142
97137.128.0.0/14137.128.0.1 to 137.131.255.254137.131.255.255262,142
98137.132.0.0/14137.132.0.1 to 137.135.255.254137.135.255.255262,142
99137.136.0.0/14137.136.0.1 to 137.139.255.254137.139.255.255262,142
100137.140.0.0/14137.140.0.1 to 137.143.255.254137.143.255.255262,142
101137.144.0.0/14137.144.0.1 to 137.147.255.254137.147.255.255262,142
102137.148.0.0/14137.148.0.1 to 137.151.255.254137.151.255.255262,142
103137.152.0.0/14137.152.0.1 to 137.155.255.254137.155.255.255262,142
104137.156.0.0/14137.156.0.1 to 137.159.255.254137.159.255.255262,142
105137.160.0.0/14137.160.0.1 to 137.163.255.254137.163.255.255262,142
106137.164.0.0/14137.164.0.1 to 137.167.255.254137.167.255.255262,142
107137.168.0.0/14137.168.0.1 to 137.171.255.254137.171.255.255262,142
108137.172.0.0/14137.172.0.1 to 137.175.255.254137.175.255.255262,142
109137.176.0.0/14137.176.0.1 to 137.179.255.254137.179.255.255262,142
110137.180.0.0/14137.180.0.1 to 137.183.255.254137.183.255.255262,142
111137.184.0.0/14137.184.0.1 to 137.187.255.254137.187.255.255262,142
112137.188.0.0/14137.188.0.1 to 137.191.255.254137.191.255.255262,142
113137.192.0.0/14137.192.0.1 to 137.195.255.254137.195.255.255262,142
114137.196.0.0/14137.196.0.1 to 137.199.255.254137.199.255.255262,142
115137.200.0.0/14137.200.0.1 to 137.203.255.254137.203.255.255262,142
116137.204.0.0/14137.204.0.1 to 137.207.255.254137.207.255.255262,142
117137.208.0.0/14137.208.0.1 to 137.211.255.254137.211.255.255262,142
118137.212.0.0/14137.212.0.1 to 137.215.255.254137.215.255.255262,142
119137.216.0.0/14137.216.0.1 to 137.219.255.254137.219.255.255262,142
120137.220.0.0/14137.220.0.1 to 137.223.255.254137.223.255.255262,142
121137.224.0.0/14137.224.0.1 to 137.227.255.254137.227.255.255262,142
122137.228.0.0/14137.228.0.1 to 137.231.255.254137.231.255.255262,142
123137.232.0.0/14137.232.0.1 to 137.235.255.254137.235.255.255262,142
124137.236.0.0/14137.236.0.1 to 137.239.255.254137.239.255.255262,142
125137.240.0.0/14137.240.0.1 to 137.243.255.254137.243.255.255262,142
126137.244.0.0/14137.244.0.1 to 137.247.255.254137.247.255.255262,142
127137.248.0.0/14137.248.0.1 to 137.251.255.254137.251.255.255262,142
128137.252.0.0/14137.252.0.1 to 137.255.255.254137.255.255.255262,142

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.