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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.

Network239.44.0.0/15
Usable hosts131,070
Subnet mask255.254.0.0
Addresses131,072
Network address
239.44.0.0
Broadcast address
239.45.255.255
First usable
239.44.0.1
Last usable
239.45.255.254
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 EF2C0000 · Integer 4012638208 to 4012769279
Reverse DNS zones
44.239.in-addr.arpa
45.239.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
Address11101111.00101100.00000000.00000000239.44.0.0
Subnet mask11111111.11111110.00000000.00000000255.254.0.0
Network11101111.00101100.00000000.00000000239.44.0.0
Broadcast11101111.00101101.11111111.11111111239.45.255.255
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)

239.44.0.0/15 makes 128 subnets of /22.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1239.44.0.0/22239.44.0.1 to 239.44.3.254239.44.3.2551,022
2239.44.4.0/22239.44.4.1 to 239.44.7.254239.44.7.2551,022
3239.44.8.0/22239.44.8.1 to 239.44.11.254239.44.11.2551,022
4239.44.12.0/22239.44.12.1 to 239.44.15.254239.44.15.2551,022
5239.44.16.0/22239.44.16.1 to 239.44.19.254239.44.19.2551,022
6239.44.20.0/22239.44.20.1 to 239.44.23.254239.44.23.2551,022
7239.44.24.0/22239.44.24.1 to 239.44.27.254239.44.27.2551,022
8239.44.28.0/22239.44.28.1 to 239.44.31.254239.44.31.2551,022
9239.44.32.0/22239.44.32.1 to 239.44.35.254239.44.35.2551,022
10239.44.36.0/22239.44.36.1 to 239.44.39.254239.44.39.2551,022
11239.44.40.0/22239.44.40.1 to 239.44.43.254239.44.43.2551,022
12239.44.44.0/22239.44.44.1 to 239.44.47.254239.44.47.2551,022
13239.44.48.0/22239.44.48.1 to 239.44.51.254239.44.51.2551,022
14239.44.52.0/22239.44.52.1 to 239.44.55.254239.44.55.2551,022
15239.44.56.0/22239.44.56.1 to 239.44.59.254239.44.59.2551,022
16239.44.60.0/22239.44.60.1 to 239.44.63.254239.44.63.2551,022
17239.44.64.0/22239.44.64.1 to 239.44.67.254239.44.67.2551,022
18239.44.68.0/22239.44.68.1 to 239.44.71.254239.44.71.2551,022
19239.44.72.0/22239.44.72.1 to 239.44.75.254239.44.75.2551,022
20239.44.76.0/22239.44.76.1 to 239.44.79.254239.44.79.2551,022
21239.44.80.0/22239.44.80.1 to 239.44.83.254239.44.83.2551,022
22239.44.84.0/22239.44.84.1 to 239.44.87.254239.44.87.2551,022
23239.44.88.0/22239.44.88.1 to 239.44.91.254239.44.91.2551,022
24239.44.92.0/22239.44.92.1 to 239.44.95.254239.44.95.2551,022
25239.44.96.0/22239.44.96.1 to 239.44.99.254239.44.99.2551,022
26239.44.100.0/22239.44.100.1 to 239.44.103.254239.44.103.2551,022
27239.44.104.0/22239.44.104.1 to 239.44.107.254239.44.107.2551,022
28239.44.108.0/22239.44.108.1 to 239.44.111.254239.44.111.2551,022
29239.44.112.0/22239.44.112.1 to 239.44.115.254239.44.115.2551,022
30239.44.116.0/22239.44.116.1 to 239.44.119.254239.44.119.2551,022
31239.44.120.0/22239.44.120.1 to 239.44.123.254239.44.123.2551,022
32239.44.124.0/22239.44.124.1 to 239.44.127.254239.44.127.2551,022
33239.44.128.0/22239.44.128.1 to 239.44.131.254239.44.131.2551,022
34239.44.132.0/22239.44.132.1 to 239.44.135.254239.44.135.2551,022
35239.44.136.0/22239.44.136.1 to 239.44.139.254239.44.139.2551,022
36239.44.140.0/22239.44.140.1 to 239.44.143.254239.44.143.2551,022
37239.44.144.0/22239.44.144.1 to 239.44.147.254239.44.147.2551,022
38239.44.148.0/22239.44.148.1 to 239.44.151.254239.44.151.2551,022
39239.44.152.0/22239.44.152.1 to 239.44.155.254239.44.155.2551,022
40239.44.156.0/22239.44.156.1 to 239.44.159.254239.44.159.2551,022
41239.44.160.0/22239.44.160.1 to 239.44.163.254239.44.163.2551,022
42239.44.164.0/22239.44.164.1 to 239.44.167.254239.44.167.2551,022
43239.44.168.0/22239.44.168.1 to 239.44.171.254239.44.171.2551,022
44239.44.172.0/22239.44.172.1 to 239.44.175.254239.44.175.2551,022
45239.44.176.0/22239.44.176.1 to 239.44.179.254239.44.179.2551,022
46239.44.180.0/22239.44.180.1 to 239.44.183.254239.44.183.2551,022
47239.44.184.0/22239.44.184.1 to 239.44.187.254239.44.187.2551,022
48239.44.188.0/22239.44.188.1 to 239.44.191.254239.44.191.2551,022
49239.44.192.0/22239.44.192.1 to 239.44.195.254239.44.195.2551,022
50239.44.196.0/22239.44.196.1 to 239.44.199.254239.44.199.2551,022
51239.44.200.0/22239.44.200.1 to 239.44.203.254239.44.203.2551,022
52239.44.204.0/22239.44.204.1 to 239.44.207.254239.44.207.2551,022
53239.44.208.0/22239.44.208.1 to 239.44.211.254239.44.211.2551,022
54239.44.212.0/22239.44.212.1 to 239.44.215.254239.44.215.2551,022
55239.44.216.0/22239.44.216.1 to 239.44.219.254239.44.219.2551,022
56239.44.220.0/22239.44.220.1 to 239.44.223.254239.44.223.2551,022
57239.44.224.0/22239.44.224.1 to 239.44.227.254239.44.227.2551,022
58239.44.228.0/22239.44.228.1 to 239.44.231.254239.44.231.2551,022
59239.44.232.0/22239.44.232.1 to 239.44.235.254239.44.235.2551,022
60239.44.236.0/22239.44.236.1 to 239.44.239.254239.44.239.2551,022
61239.44.240.0/22239.44.240.1 to 239.44.243.254239.44.243.2551,022
62239.44.244.0/22239.44.244.1 to 239.44.247.254239.44.247.2551,022
63239.44.248.0/22239.44.248.1 to 239.44.251.254239.44.251.2551,022
64239.44.252.0/22239.44.252.1 to 239.44.255.254239.44.255.2551,022
65239.45.0.0/22239.45.0.1 to 239.45.3.254239.45.3.2551,022
66239.45.4.0/22239.45.4.1 to 239.45.7.254239.45.7.2551,022
67239.45.8.0/22239.45.8.1 to 239.45.11.254239.45.11.2551,022
68239.45.12.0/22239.45.12.1 to 239.45.15.254239.45.15.2551,022
69239.45.16.0/22239.45.16.1 to 239.45.19.254239.45.19.2551,022
70239.45.20.0/22239.45.20.1 to 239.45.23.254239.45.23.2551,022
71239.45.24.0/22239.45.24.1 to 239.45.27.254239.45.27.2551,022
72239.45.28.0/22239.45.28.1 to 239.45.31.254239.45.31.2551,022
73239.45.32.0/22239.45.32.1 to 239.45.35.254239.45.35.2551,022
74239.45.36.0/22239.45.36.1 to 239.45.39.254239.45.39.2551,022
75239.45.40.0/22239.45.40.1 to 239.45.43.254239.45.43.2551,022
76239.45.44.0/22239.45.44.1 to 239.45.47.254239.45.47.2551,022
77239.45.48.0/22239.45.48.1 to 239.45.51.254239.45.51.2551,022
78239.45.52.0/22239.45.52.1 to 239.45.55.254239.45.55.2551,022
79239.45.56.0/22239.45.56.1 to 239.45.59.254239.45.59.2551,022
80239.45.60.0/22239.45.60.1 to 239.45.63.254239.45.63.2551,022
81239.45.64.0/22239.45.64.1 to 239.45.67.254239.45.67.2551,022
82239.45.68.0/22239.45.68.1 to 239.45.71.254239.45.71.2551,022
83239.45.72.0/22239.45.72.1 to 239.45.75.254239.45.75.2551,022
84239.45.76.0/22239.45.76.1 to 239.45.79.254239.45.79.2551,022
85239.45.80.0/22239.45.80.1 to 239.45.83.254239.45.83.2551,022
86239.45.84.0/22239.45.84.1 to 239.45.87.254239.45.87.2551,022
87239.45.88.0/22239.45.88.1 to 239.45.91.254239.45.91.2551,022
88239.45.92.0/22239.45.92.1 to 239.45.95.254239.45.95.2551,022
89239.45.96.0/22239.45.96.1 to 239.45.99.254239.45.99.2551,022
90239.45.100.0/22239.45.100.1 to 239.45.103.254239.45.103.2551,022
91239.45.104.0/22239.45.104.1 to 239.45.107.254239.45.107.2551,022
92239.45.108.0/22239.45.108.1 to 239.45.111.254239.45.111.2551,022
93239.45.112.0/22239.45.112.1 to 239.45.115.254239.45.115.2551,022
94239.45.116.0/22239.45.116.1 to 239.45.119.254239.45.119.2551,022
95239.45.120.0/22239.45.120.1 to 239.45.123.254239.45.123.2551,022
96239.45.124.0/22239.45.124.1 to 239.45.127.254239.45.127.2551,022
97239.45.128.0/22239.45.128.1 to 239.45.131.254239.45.131.2551,022
98239.45.132.0/22239.45.132.1 to 239.45.135.254239.45.135.2551,022
99239.45.136.0/22239.45.136.1 to 239.45.139.254239.45.139.2551,022
100239.45.140.0/22239.45.140.1 to 239.45.143.254239.45.143.2551,022
101239.45.144.0/22239.45.144.1 to 239.45.147.254239.45.147.2551,022
102239.45.148.0/22239.45.148.1 to 239.45.151.254239.45.151.2551,022
103239.45.152.0/22239.45.152.1 to 239.45.155.254239.45.155.2551,022
104239.45.156.0/22239.45.156.1 to 239.45.159.254239.45.159.2551,022
105239.45.160.0/22239.45.160.1 to 239.45.163.254239.45.163.2551,022
106239.45.164.0/22239.45.164.1 to 239.45.167.254239.45.167.2551,022
107239.45.168.0/22239.45.168.1 to 239.45.171.254239.45.171.2551,022
108239.45.172.0/22239.45.172.1 to 239.45.175.254239.45.175.2551,022
109239.45.176.0/22239.45.176.1 to 239.45.179.254239.45.179.2551,022
110239.45.180.0/22239.45.180.1 to 239.45.183.254239.45.183.2551,022
111239.45.184.0/22239.45.184.1 to 239.45.187.254239.45.187.2551,022
112239.45.188.0/22239.45.188.1 to 239.45.191.254239.45.191.2551,022
113239.45.192.0/22239.45.192.1 to 239.45.195.254239.45.195.2551,022
114239.45.196.0/22239.45.196.1 to 239.45.199.254239.45.199.2551,022
115239.45.200.0/22239.45.200.1 to 239.45.203.254239.45.203.2551,022
116239.45.204.0/22239.45.204.1 to 239.45.207.254239.45.207.2551,022
117239.45.208.0/22239.45.208.1 to 239.45.211.254239.45.211.2551,022
118239.45.212.0/22239.45.212.1 to 239.45.215.254239.45.215.2551,022
119239.45.216.0/22239.45.216.1 to 239.45.219.254239.45.219.2551,022
120239.45.220.0/22239.45.220.1 to 239.45.223.254239.45.223.2551,022
121239.45.224.0/22239.45.224.1 to 239.45.227.254239.45.227.2551,022
122239.45.228.0/22239.45.228.1 to 239.45.231.254239.45.231.2551,022
123239.45.232.0/22239.45.232.1 to 239.45.235.254239.45.235.2551,022
124239.45.236.0/22239.45.236.1 to 239.45.239.254239.45.239.2551,022
125239.45.240.0/22239.45.240.1 to 239.45.243.254239.45.243.2551,022
126239.45.244.0/22239.45.244.1 to 239.45.247.254239.45.247.2551,022
127239.45.248.0/22239.45.248.1 to 239.45.251.254239.45.251.2551,022
128239.45.252.0/22239.45.252.1 to 239.45.255.254239.45.255.2551,022

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.