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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.

Network249.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
249.0.0.0
Broadcast address
249.255.255.255
First usable
249.0.0.1
Last usable
249.255.255.254
Usable hosts
16,777,214 (16,777,216 less the network and broadcast addresses)
Subnet mask
255.0.0.0
Wildcard mask
0.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/8
Type
Reserved 240.0.0.0/4
Future use; not usable on most systems
Old class
E (reserved)
As numbers
Hex F9000000 · Integer 4177526784 to 4194303999
Reverse DNS zone
249.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11111001..00000000.00000000.00000000249.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network11111001..00000000.00000000.00000000249.0.0.0
Broadcast11111001..11111111.11111111.11111111249.255.255.255
Split into smaller subnets/15
/9 (2)/10 (4)/11 (8)/12 (16)/13 (32)/14 (64)/15 (128)/16 (256)/17 (512)/18 (1,024)/19 (2,048)/20 (4,096)

249.0.0.0/8 makes 128 subnets of /15.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1249.0.0.0/15249.0.0.1 to 249.1.255.254249.1.255.255131,070
2249.2.0.0/15249.2.0.1 to 249.3.255.254249.3.255.255131,070
3249.4.0.0/15249.4.0.1 to 249.5.255.254249.5.255.255131,070
4249.6.0.0/15249.6.0.1 to 249.7.255.254249.7.255.255131,070
5249.8.0.0/15249.8.0.1 to 249.9.255.254249.9.255.255131,070
6249.10.0.0/15249.10.0.1 to 249.11.255.254249.11.255.255131,070
7249.12.0.0/15249.12.0.1 to 249.13.255.254249.13.255.255131,070
8249.14.0.0/15249.14.0.1 to 249.15.255.254249.15.255.255131,070
9249.16.0.0/15249.16.0.1 to 249.17.255.254249.17.255.255131,070
10249.18.0.0/15249.18.0.1 to 249.19.255.254249.19.255.255131,070
11249.20.0.0/15249.20.0.1 to 249.21.255.254249.21.255.255131,070
12249.22.0.0/15249.22.0.1 to 249.23.255.254249.23.255.255131,070
13249.24.0.0/15249.24.0.1 to 249.25.255.254249.25.255.255131,070
14249.26.0.0/15249.26.0.1 to 249.27.255.254249.27.255.255131,070
15249.28.0.0/15249.28.0.1 to 249.29.255.254249.29.255.255131,070
16249.30.0.0/15249.30.0.1 to 249.31.255.254249.31.255.255131,070
17249.32.0.0/15249.32.0.1 to 249.33.255.254249.33.255.255131,070
18249.34.0.0/15249.34.0.1 to 249.35.255.254249.35.255.255131,070
19249.36.0.0/15249.36.0.1 to 249.37.255.254249.37.255.255131,070
20249.38.0.0/15249.38.0.1 to 249.39.255.254249.39.255.255131,070
21249.40.0.0/15249.40.0.1 to 249.41.255.254249.41.255.255131,070
22249.42.0.0/15249.42.0.1 to 249.43.255.254249.43.255.255131,070
23249.44.0.0/15249.44.0.1 to 249.45.255.254249.45.255.255131,070
24249.46.0.0/15249.46.0.1 to 249.47.255.254249.47.255.255131,070
25249.48.0.0/15249.48.0.1 to 249.49.255.254249.49.255.255131,070
26249.50.0.0/15249.50.0.1 to 249.51.255.254249.51.255.255131,070
27249.52.0.0/15249.52.0.1 to 249.53.255.254249.53.255.255131,070
28249.54.0.0/15249.54.0.1 to 249.55.255.254249.55.255.255131,070
29249.56.0.0/15249.56.0.1 to 249.57.255.254249.57.255.255131,070
30249.58.0.0/15249.58.0.1 to 249.59.255.254249.59.255.255131,070
31249.60.0.0/15249.60.0.1 to 249.61.255.254249.61.255.255131,070
32249.62.0.0/15249.62.0.1 to 249.63.255.254249.63.255.255131,070
33249.64.0.0/15249.64.0.1 to 249.65.255.254249.65.255.255131,070
34249.66.0.0/15249.66.0.1 to 249.67.255.254249.67.255.255131,070
35249.68.0.0/15249.68.0.1 to 249.69.255.254249.69.255.255131,070
36249.70.0.0/15249.70.0.1 to 249.71.255.254249.71.255.255131,070
37249.72.0.0/15249.72.0.1 to 249.73.255.254249.73.255.255131,070
38249.74.0.0/15249.74.0.1 to 249.75.255.254249.75.255.255131,070
39249.76.0.0/15249.76.0.1 to 249.77.255.254249.77.255.255131,070
40249.78.0.0/15249.78.0.1 to 249.79.255.254249.79.255.255131,070
41249.80.0.0/15249.80.0.1 to 249.81.255.254249.81.255.255131,070
42249.82.0.0/15249.82.0.1 to 249.83.255.254249.83.255.255131,070
43249.84.0.0/15249.84.0.1 to 249.85.255.254249.85.255.255131,070
44249.86.0.0/15249.86.0.1 to 249.87.255.254249.87.255.255131,070
45249.88.0.0/15249.88.0.1 to 249.89.255.254249.89.255.255131,070
46249.90.0.0/15249.90.0.1 to 249.91.255.254249.91.255.255131,070
47249.92.0.0/15249.92.0.1 to 249.93.255.254249.93.255.255131,070
48249.94.0.0/15249.94.0.1 to 249.95.255.254249.95.255.255131,070
49249.96.0.0/15249.96.0.1 to 249.97.255.254249.97.255.255131,070
50249.98.0.0/15249.98.0.1 to 249.99.255.254249.99.255.255131,070
51249.100.0.0/15249.100.0.1 to 249.101.255.254249.101.255.255131,070
52249.102.0.0/15249.102.0.1 to 249.103.255.254249.103.255.255131,070
53249.104.0.0/15249.104.0.1 to 249.105.255.254249.105.255.255131,070
54249.106.0.0/15249.106.0.1 to 249.107.255.254249.107.255.255131,070
55249.108.0.0/15249.108.0.1 to 249.109.255.254249.109.255.255131,070
56249.110.0.0/15249.110.0.1 to 249.111.255.254249.111.255.255131,070
57249.112.0.0/15249.112.0.1 to 249.113.255.254249.113.255.255131,070
58249.114.0.0/15249.114.0.1 to 249.115.255.254249.115.255.255131,070
59249.116.0.0/15249.116.0.1 to 249.117.255.254249.117.255.255131,070
60249.118.0.0/15249.118.0.1 to 249.119.255.254249.119.255.255131,070
61249.120.0.0/15249.120.0.1 to 249.121.255.254249.121.255.255131,070
62249.122.0.0/15249.122.0.1 to 249.123.255.254249.123.255.255131,070
63249.124.0.0/15249.124.0.1 to 249.125.255.254249.125.255.255131,070
64249.126.0.0/15249.126.0.1 to 249.127.255.254249.127.255.255131,070
65249.128.0.0/15249.128.0.1 to 249.129.255.254249.129.255.255131,070
66249.130.0.0/15249.130.0.1 to 249.131.255.254249.131.255.255131,070
67249.132.0.0/15249.132.0.1 to 249.133.255.254249.133.255.255131,070
68249.134.0.0/15249.134.0.1 to 249.135.255.254249.135.255.255131,070
69249.136.0.0/15249.136.0.1 to 249.137.255.254249.137.255.255131,070
70249.138.0.0/15249.138.0.1 to 249.139.255.254249.139.255.255131,070
71249.140.0.0/15249.140.0.1 to 249.141.255.254249.141.255.255131,070
72249.142.0.0/15249.142.0.1 to 249.143.255.254249.143.255.255131,070
73249.144.0.0/15249.144.0.1 to 249.145.255.254249.145.255.255131,070
74249.146.0.0/15249.146.0.1 to 249.147.255.254249.147.255.255131,070
75249.148.0.0/15249.148.0.1 to 249.149.255.254249.149.255.255131,070
76249.150.0.0/15249.150.0.1 to 249.151.255.254249.151.255.255131,070
77249.152.0.0/15249.152.0.1 to 249.153.255.254249.153.255.255131,070
78249.154.0.0/15249.154.0.1 to 249.155.255.254249.155.255.255131,070
79249.156.0.0/15249.156.0.1 to 249.157.255.254249.157.255.255131,070
80249.158.0.0/15249.158.0.1 to 249.159.255.254249.159.255.255131,070
81249.160.0.0/15249.160.0.1 to 249.161.255.254249.161.255.255131,070
82249.162.0.0/15249.162.0.1 to 249.163.255.254249.163.255.255131,070
83249.164.0.0/15249.164.0.1 to 249.165.255.254249.165.255.255131,070
84249.166.0.0/15249.166.0.1 to 249.167.255.254249.167.255.255131,070
85249.168.0.0/15249.168.0.1 to 249.169.255.254249.169.255.255131,070
86249.170.0.0/15249.170.0.1 to 249.171.255.254249.171.255.255131,070
87249.172.0.0/15249.172.0.1 to 249.173.255.254249.173.255.255131,070
88249.174.0.0/15249.174.0.1 to 249.175.255.254249.175.255.255131,070
89249.176.0.0/15249.176.0.1 to 249.177.255.254249.177.255.255131,070
90249.178.0.0/15249.178.0.1 to 249.179.255.254249.179.255.255131,070
91249.180.0.0/15249.180.0.1 to 249.181.255.254249.181.255.255131,070
92249.182.0.0/15249.182.0.1 to 249.183.255.254249.183.255.255131,070
93249.184.0.0/15249.184.0.1 to 249.185.255.254249.185.255.255131,070
94249.186.0.0/15249.186.0.1 to 249.187.255.254249.187.255.255131,070
95249.188.0.0/15249.188.0.1 to 249.189.255.254249.189.255.255131,070
96249.190.0.0/15249.190.0.1 to 249.191.255.254249.191.255.255131,070
97249.192.0.0/15249.192.0.1 to 249.193.255.254249.193.255.255131,070
98249.194.0.0/15249.194.0.1 to 249.195.255.254249.195.255.255131,070
99249.196.0.0/15249.196.0.1 to 249.197.255.254249.197.255.255131,070
100249.198.0.0/15249.198.0.1 to 249.199.255.254249.199.255.255131,070
101249.200.0.0/15249.200.0.1 to 249.201.255.254249.201.255.255131,070
102249.202.0.0/15249.202.0.1 to 249.203.255.254249.203.255.255131,070
103249.204.0.0/15249.204.0.1 to 249.205.255.254249.205.255.255131,070
104249.206.0.0/15249.206.0.1 to 249.207.255.254249.207.255.255131,070
105249.208.0.0/15249.208.0.1 to 249.209.255.254249.209.255.255131,070
106249.210.0.0/15249.210.0.1 to 249.211.255.254249.211.255.255131,070
107249.212.0.0/15249.212.0.1 to 249.213.255.254249.213.255.255131,070
108249.214.0.0/15249.214.0.1 to 249.215.255.254249.215.255.255131,070
109249.216.0.0/15249.216.0.1 to 249.217.255.254249.217.255.255131,070
110249.218.0.0/15249.218.0.1 to 249.219.255.254249.219.255.255131,070
111249.220.0.0/15249.220.0.1 to 249.221.255.254249.221.255.255131,070
112249.222.0.0/15249.222.0.1 to 249.223.255.254249.223.255.255131,070
113249.224.0.0/15249.224.0.1 to 249.225.255.254249.225.255.255131,070
114249.226.0.0/15249.226.0.1 to 249.227.255.254249.227.255.255131,070
115249.228.0.0/15249.228.0.1 to 249.229.255.254249.229.255.255131,070
116249.230.0.0/15249.230.0.1 to 249.231.255.254249.231.255.255131,070
117249.232.0.0/15249.232.0.1 to 249.233.255.254249.233.255.255131,070
118249.234.0.0/15249.234.0.1 to 249.235.255.254249.235.255.255131,070
119249.236.0.0/15249.236.0.1 to 249.237.255.254249.237.255.255131,070
120249.238.0.0/15249.238.0.1 to 249.239.255.254249.239.255.255131,070
121249.240.0.0/15249.240.0.1 to 249.241.255.254249.241.255.255131,070
122249.242.0.0/15249.242.0.1 to 249.243.255.254249.243.255.255131,070
123249.244.0.0/15249.244.0.1 to 249.245.255.254249.245.255.255131,070
124249.246.0.0/15249.246.0.1 to 249.247.255.254249.247.255.255131,070
125249.248.0.0/15249.248.0.1 to 249.249.255.254249.249.255.255131,070
126249.250.0.0/15249.250.0.1 to 249.251.255.254249.251.255.255131,070
127249.252.0.0/15249.252.0.1 to 249.253.255.254249.253.255.255131,070
128249.254.0.0/15249.254.0.1 to 249.255.255.254249.255.255.255131,070

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.