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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.

Network235.166.0.0/15
Usable hosts131,070
Subnet mask255.254.0.0
Addresses131,072
Network address
235.166.0.0
Broadcast address
235.167.255.255
First usable
235.166.0.1
Last usable
235.167.255.254
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
Multicast 224.0.0.0/4
One-to-many traffic, such as IPTV and routing protocols
Old class
D (multicast)
As numbers
Hex EBA60000 · Integer 3953524736 to 3953655807
Reverse DNS zones
166.235.in-addr.arpa
167.235.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
Address11101011.10100110.00000000.00000000235.166.0.0
Subnet mask11111111.11111110.00000000.00000000255.254.0.0
Network11101011.10100110.00000000.00000000235.166.0.0
Broadcast11101011.10100111.11111111.11111111235.167.255.255
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)

235.166.0.0/15 makes 128 subnets of /22.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1235.166.0.0/22235.166.0.1 to 235.166.3.254235.166.3.2551,022
2235.166.4.0/22235.166.4.1 to 235.166.7.254235.166.7.2551,022
3235.166.8.0/22235.166.8.1 to 235.166.11.254235.166.11.2551,022
4235.166.12.0/22235.166.12.1 to 235.166.15.254235.166.15.2551,022
5235.166.16.0/22235.166.16.1 to 235.166.19.254235.166.19.2551,022
6235.166.20.0/22235.166.20.1 to 235.166.23.254235.166.23.2551,022
7235.166.24.0/22235.166.24.1 to 235.166.27.254235.166.27.2551,022
8235.166.28.0/22235.166.28.1 to 235.166.31.254235.166.31.2551,022
9235.166.32.0/22235.166.32.1 to 235.166.35.254235.166.35.2551,022
10235.166.36.0/22235.166.36.1 to 235.166.39.254235.166.39.2551,022
11235.166.40.0/22235.166.40.1 to 235.166.43.254235.166.43.2551,022
12235.166.44.0/22235.166.44.1 to 235.166.47.254235.166.47.2551,022
13235.166.48.0/22235.166.48.1 to 235.166.51.254235.166.51.2551,022
14235.166.52.0/22235.166.52.1 to 235.166.55.254235.166.55.2551,022
15235.166.56.0/22235.166.56.1 to 235.166.59.254235.166.59.2551,022
16235.166.60.0/22235.166.60.1 to 235.166.63.254235.166.63.2551,022
17235.166.64.0/22235.166.64.1 to 235.166.67.254235.166.67.2551,022
18235.166.68.0/22235.166.68.1 to 235.166.71.254235.166.71.2551,022
19235.166.72.0/22235.166.72.1 to 235.166.75.254235.166.75.2551,022
20235.166.76.0/22235.166.76.1 to 235.166.79.254235.166.79.2551,022
21235.166.80.0/22235.166.80.1 to 235.166.83.254235.166.83.2551,022
22235.166.84.0/22235.166.84.1 to 235.166.87.254235.166.87.2551,022
23235.166.88.0/22235.166.88.1 to 235.166.91.254235.166.91.2551,022
24235.166.92.0/22235.166.92.1 to 235.166.95.254235.166.95.2551,022
25235.166.96.0/22235.166.96.1 to 235.166.99.254235.166.99.2551,022
26235.166.100.0/22235.166.100.1 to 235.166.103.254235.166.103.2551,022
27235.166.104.0/22235.166.104.1 to 235.166.107.254235.166.107.2551,022
28235.166.108.0/22235.166.108.1 to 235.166.111.254235.166.111.2551,022
29235.166.112.0/22235.166.112.1 to 235.166.115.254235.166.115.2551,022
30235.166.116.0/22235.166.116.1 to 235.166.119.254235.166.119.2551,022
31235.166.120.0/22235.166.120.1 to 235.166.123.254235.166.123.2551,022
32235.166.124.0/22235.166.124.1 to 235.166.127.254235.166.127.2551,022
33235.166.128.0/22235.166.128.1 to 235.166.131.254235.166.131.2551,022
34235.166.132.0/22235.166.132.1 to 235.166.135.254235.166.135.2551,022
35235.166.136.0/22235.166.136.1 to 235.166.139.254235.166.139.2551,022
36235.166.140.0/22235.166.140.1 to 235.166.143.254235.166.143.2551,022
37235.166.144.0/22235.166.144.1 to 235.166.147.254235.166.147.2551,022
38235.166.148.0/22235.166.148.1 to 235.166.151.254235.166.151.2551,022
39235.166.152.0/22235.166.152.1 to 235.166.155.254235.166.155.2551,022
40235.166.156.0/22235.166.156.1 to 235.166.159.254235.166.159.2551,022
41235.166.160.0/22235.166.160.1 to 235.166.163.254235.166.163.2551,022
42235.166.164.0/22235.166.164.1 to 235.166.167.254235.166.167.2551,022
43235.166.168.0/22235.166.168.1 to 235.166.171.254235.166.171.2551,022
44235.166.172.0/22235.166.172.1 to 235.166.175.254235.166.175.2551,022
45235.166.176.0/22235.166.176.1 to 235.166.179.254235.166.179.2551,022
46235.166.180.0/22235.166.180.1 to 235.166.183.254235.166.183.2551,022
47235.166.184.0/22235.166.184.1 to 235.166.187.254235.166.187.2551,022
48235.166.188.0/22235.166.188.1 to 235.166.191.254235.166.191.2551,022
49235.166.192.0/22235.166.192.1 to 235.166.195.254235.166.195.2551,022
50235.166.196.0/22235.166.196.1 to 235.166.199.254235.166.199.2551,022
51235.166.200.0/22235.166.200.1 to 235.166.203.254235.166.203.2551,022
52235.166.204.0/22235.166.204.1 to 235.166.207.254235.166.207.2551,022
53235.166.208.0/22235.166.208.1 to 235.166.211.254235.166.211.2551,022
54235.166.212.0/22235.166.212.1 to 235.166.215.254235.166.215.2551,022
55235.166.216.0/22235.166.216.1 to 235.166.219.254235.166.219.2551,022
56235.166.220.0/22235.166.220.1 to 235.166.223.254235.166.223.2551,022
57235.166.224.0/22235.166.224.1 to 235.166.227.254235.166.227.2551,022
58235.166.228.0/22235.166.228.1 to 235.166.231.254235.166.231.2551,022
59235.166.232.0/22235.166.232.1 to 235.166.235.254235.166.235.2551,022
60235.166.236.0/22235.166.236.1 to 235.166.239.254235.166.239.2551,022
61235.166.240.0/22235.166.240.1 to 235.166.243.254235.166.243.2551,022
62235.166.244.0/22235.166.244.1 to 235.166.247.254235.166.247.2551,022
63235.166.248.0/22235.166.248.1 to 235.166.251.254235.166.251.2551,022
64235.166.252.0/22235.166.252.1 to 235.166.255.254235.166.255.2551,022
65235.167.0.0/22235.167.0.1 to 235.167.3.254235.167.3.2551,022
66235.167.4.0/22235.167.4.1 to 235.167.7.254235.167.7.2551,022
67235.167.8.0/22235.167.8.1 to 235.167.11.254235.167.11.2551,022
68235.167.12.0/22235.167.12.1 to 235.167.15.254235.167.15.2551,022
69235.167.16.0/22235.167.16.1 to 235.167.19.254235.167.19.2551,022
70235.167.20.0/22235.167.20.1 to 235.167.23.254235.167.23.2551,022
71235.167.24.0/22235.167.24.1 to 235.167.27.254235.167.27.2551,022
72235.167.28.0/22235.167.28.1 to 235.167.31.254235.167.31.2551,022
73235.167.32.0/22235.167.32.1 to 235.167.35.254235.167.35.2551,022
74235.167.36.0/22235.167.36.1 to 235.167.39.254235.167.39.2551,022
75235.167.40.0/22235.167.40.1 to 235.167.43.254235.167.43.2551,022
76235.167.44.0/22235.167.44.1 to 235.167.47.254235.167.47.2551,022
77235.167.48.0/22235.167.48.1 to 235.167.51.254235.167.51.2551,022
78235.167.52.0/22235.167.52.1 to 235.167.55.254235.167.55.2551,022
79235.167.56.0/22235.167.56.1 to 235.167.59.254235.167.59.2551,022
80235.167.60.0/22235.167.60.1 to 235.167.63.254235.167.63.2551,022
81235.167.64.0/22235.167.64.1 to 235.167.67.254235.167.67.2551,022
82235.167.68.0/22235.167.68.1 to 235.167.71.254235.167.71.2551,022
83235.167.72.0/22235.167.72.1 to 235.167.75.254235.167.75.2551,022
84235.167.76.0/22235.167.76.1 to 235.167.79.254235.167.79.2551,022
85235.167.80.0/22235.167.80.1 to 235.167.83.254235.167.83.2551,022
86235.167.84.0/22235.167.84.1 to 235.167.87.254235.167.87.2551,022
87235.167.88.0/22235.167.88.1 to 235.167.91.254235.167.91.2551,022
88235.167.92.0/22235.167.92.1 to 235.167.95.254235.167.95.2551,022
89235.167.96.0/22235.167.96.1 to 235.167.99.254235.167.99.2551,022
90235.167.100.0/22235.167.100.1 to 235.167.103.254235.167.103.2551,022
91235.167.104.0/22235.167.104.1 to 235.167.107.254235.167.107.2551,022
92235.167.108.0/22235.167.108.1 to 235.167.111.254235.167.111.2551,022
93235.167.112.0/22235.167.112.1 to 235.167.115.254235.167.115.2551,022
94235.167.116.0/22235.167.116.1 to 235.167.119.254235.167.119.2551,022
95235.167.120.0/22235.167.120.1 to 235.167.123.254235.167.123.2551,022
96235.167.124.0/22235.167.124.1 to 235.167.127.254235.167.127.2551,022
97235.167.128.0/22235.167.128.1 to 235.167.131.254235.167.131.2551,022
98235.167.132.0/22235.167.132.1 to 235.167.135.254235.167.135.2551,022
99235.167.136.0/22235.167.136.1 to 235.167.139.254235.167.139.2551,022
100235.167.140.0/22235.167.140.1 to 235.167.143.254235.167.143.2551,022
101235.167.144.0/22235.167.144.1 to 235.167.147.254235.167.147.2551,022
102235.167.148.0/22235.167.148.1 to 235.167.151.254235.167.151.2551,022
103235.167.152.0/22235.167.152.1 to 235.167.155.254235.167.155.2551,022
104235.167.156.0/22235.167.156.1 to 235.167.159.254235.167.159.2551,022
105235.167.160.0/22235.167.160.1 to 235.167.163.254235.167.163.2551,022
106235.167.164.0/22235.167.164.1 to 235.167.167.254235.167.167.2551,022
107235.167.168.0/22235.167.168.1 to 235.167.171.254235.167.171.2551,022
108235.167.172.0/22235.167.172.1 to 235.167.175.254235.167.175.2551,022
109235.167.176.0/22235.167.176.1 to 235.167.179.254235.167.179.2551,022
110235.167.180.0/22235.167.180.1 to 235.167.183.254235.167.183.2551,022
111235.167.184.0/22235.167.184.1 to 235.167.187.254235.167.187.2551,022
112235.167.188.0/22235.167.188.1 to 235.167.191.254235.167.191.2551,022
113235.167.192.0/22235.167.192.1 to 235.167.195.254235.167.195.2551,022
114235.167.196.0/22235.167.196.1 to 235.167.199.254235.167.199.2551,022
115235.167.200.0/22235.167.200.1 to 235.167.203.254235.167.203.2551,022
116235.167.204.0/22235.167.204.1 to 235.167.207.254235.167.207.2551,022
117235.167.208.0/22235.167.208.1 to 235.167.211.254235.167.211.2551,022
118235.167.212.0/22235.167.212.1 to 235.167.215.254235.167.215.2551,022
119235.167.216.0/22235.167.216.1 to 235.167.219.254235.167.219.2551,022
120235.167.220.0/22235.167.220.1 to 235.167.223.254235.167.223.2551,022
121235.167.224.0/22235.167.224.1 to 235.167.227.254235.167.227.2551,022
122235.167.228.0/22235.167.228.1 to 235.167.231.254235.167.231.2551,022
123235.167.232.0/22235.167.232.1 to 235.167.235.254235.167.235.2551,022
124235.167.236.0/22235.167.236.1 to 235.167.239.254235.167.239.2551,022
125235.167.240.0/22235.167.240.1 to 235.167.243.254235.167.243.2551,022
126235.167.244.0/22235.167.244.1 to 235.167.247.254235.167.247.2551,022
127235.167.248.0/22235.167.248.1 to 235.167.251.254235.167.251.2551,022
128235.167.252.0/22235.167.252.1 to 235.167.255.254235.167.255.2551,022

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.