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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.

Network248.0.0.0/7
Usable hosts33,554,430
Subnet mask254.0.0.0
Addresses33,554,432
Network address
248.0.0.0
Broadcast address
249.255.255.255
First usable
248.0.0.1
Last usable
249.255.255.254
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
Reserved 240.0.0.0/4
Future use; not usable on most systems
Old class
E (reserved)
As numbers
Hex F8000000 · Integer 4160749568 to 4194303999
Reverse DNS zones
248.in-addr.arpa
249.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
Address11111000.00000000.00000000.00000000248.0.0.0
Subnet mask11111110.00000000.00000000.00000000254.0.0.0
Network11111000.00000000.00000000.00000000248.0.0.0
Broadcast11111001.11111111.11111111.11111111249.255.255.255
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)

248.0.0.0/7 makes 128 subnets of /14.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1248.0.0.0/14248.0.0.1 to 248.3.255.254248.3.255.255262,142
2248.4.0.0/14248.4.0.1 to 248.7.255.254248.7.255.255262,142
3248.8.0.0/14248.8.0.1 to 248.11.255.254248.11.255.255262,142
4248.12.0.0/14248.12.0.1 to 248.15.255.254248.15.255.255262,142
5248.16.0.0/14248.16.0.1 to 248.19.255.254248.19.255.255262,142
6248.20.0.0/14248.20.0.1 to 248.23.255.254248.23.255.255262,142
7248.24.0.0/14248.24.0.1 to 248.27.255.254248.27.255.255262,142
8248.28.0.0/14248.28.0.1 to 248.31.255.254248.31.255.255262,142
9248.32.0.0/14248.32.0.1 to 248.35.255.254248.35.255.255262,142
10248.36.0.0/14248.36.0.1 to 248.39.255.254248.39.255.255262,142
11248.40.0.0/14248.40.0.1 to 248.43.255.254248.43.255.255262,142
12248.44.0.0/14248.44.0.1 to 248.47.255.254248.47.255.255262,142
13248.48.0.0/14248.48.0.1 to 248.51.255.254248.51.255.255262,142
14248.52.0.0/14248.52.0.1 to 248.55.255.254248.55.255.255262,142
15248.56.0.0/14248.56.0.1 to 248.59.255.254248.59.255.255262,142
16248.60.0.0/14248.60.0.1 to 248.63.255.254248.63.255.255262,142
17248.64.0.0/14248.64.0.1 to 248.67.255.254248.67.255.255262,142
18248.68.0.0/14248.68.0.1 to 248.71.255.254248.71.255.255262,142
19248.72.0.0/14248.72.0.1 to 248.75.255.254248.75.255.255262,142
20248.76.0.0/14248.76.0.1 to 248.79.255.254248.79.255.255262,142
21248.80.0.0/14248.80.0.1 to 248.83.255.254248.83.255.255262,142
22248.84.0.0/14248.84.0.1 to 248.87.255.254248.87.255.255262,142
23248.88.0.0/14248.88.0.1 to 248.91.255.254248.91.255.255262,142
24248.92.0.0/14248.92.0.1 to 248.95.255.254248.95.255.255262,142
25248.96.0.0/14248.96.0.1 to 248.99.255.254248.99.255.255262,142
26248.100.0.0/14248.100.0.1 to 248.103.255.254248.103.255.255262,142
27248.104.0.0/14248.104.0.1 to 248.107.255.254248.107.255.255262,142
28248.108.0.0/14248.108.0.1 to 248.111.255.254248.111.255.255262,142
29248.112.0.0/14248.112.0.1 to 248.115.255.254248.115.255.255262,142
30248.116.0.0/14248.116.0.1 to 248.119.255.254248.119.255.255262,142
31248.120.0.0/14248.120.0.1 to 248.123.255.254248.123.255.255262,142
32248.124.0.0/14248.124.0.1 to 248.127.255.254248.127.255.255262,142
33248.128.0.0/14248.128.0.1 to 248.131.255.254248.131.255.255262,142
34248.132.0.0/14248.132.0.1 to 248.135.255.254248.135.255.255262,142
35248.136.0.0/14248.136.0.1 to 248.139.255.254248.139.255.255262,142
36248.140.0.0/14248.140.0.1 to 248.143.255.254248.143.255.255262,142
37248.144.0.0/14248.144.0.1 to 248.147.255.254248.147.255.255262,142
38248.148.0.0/14248.148.0.1 to 248.151.255.254248.151.255.255262,142
39248.152.0.0/14248.152.0.1 to 248.155.255.254248.155.255.255262,142
40248.156.0.0/14248.156.0.1 to 248.159.255.254248.159.255.255262,142
41248.160.0.0/14248.160.0.1 to 248.163.255.254248.163.255.255262,142
42248.164.0.0/14248.164.0.1 to 248.167.255.254248.167.255.255262,142
43248.168.0.0/14248.168.0.1 to 248.171.255.254248.171.255.255262,142
44248.172.0.0/14248.172.0.1 to 248.175.255.254248.175.255.255262,142
45248.176.0.0/14248.176.0.1 to 248.179.255.254248.179.255.255262,142
46248.180.0.0/14248.180.0.1 to 248.183.255.254248.183.255.255262,142
47248.184.0.0/14248.184.0.1 to 248.187.255.254248.187.255.255262,142
48248.188.0.0/14248.188.0.1 to 248.191.255.254248.191.255.255262,142
49248.192.0.0/14248.192.0.1 to 248.195.255.254248.195.255.255262,142
50248.196.0.0/14248.196.0.1 to 248.199.255.254248.199.255.255262,142
51248.200.0.0/14248.200.0.1 to 248.203.255.254248.203.255.255262,142
52248.204.0.0/14248.204.0.1 to 248.207.255.254248.207.255.255262,142
53248.208.0.0/14248.208.0.1 to 248.211.255.254248.211.255.255262,142
54248.212.0.0/14248.212.0.1 to 248.215.255.254248.215.255.255262,142
55248.216.0.0/14248.216.0.1 to 248.219.255.254248.219.255.255262,142
56248.220.0.0/14248.220.0.1 to 248.223.255.254248.223.255.255262,142
57248.224.0.0/14248.224.0.1 to 248.227.255.254248.227.255.255262,142
58248.228.0.0/14248.228.0.1 to 248.231.255.254248.231.255.255262,142
59248.232.0.0/14248.232.0.1 to 248.235.255.254248.235.255.255262,142
60248.236.0.0/14248.236.0.1 to 248.239.255.254248.239.255.255262,142
61248.240.0.0/14248.240.0.1 to 248.243.255.254248.243.255.255262,142
62248.244.0.0/14248.244.0.1 to 248.247.255.254248.247.255.255262,142
63248.248.0.0/14248.248.0.1 to 248.251.255.254248.251.255.255262,142
64248.252.0.0/14248.252.0.1 to 248.255.255.254248.255.255.255262,142
65249.0.0.0/14249.0.0.1 to 249.3.255.254249.3.255.255262,142
66249.4.0.0/14249.4.0.1 to 249.7.255.254249.7.255.255262,142
67249.8.0.0/14249.8.0.1 to 249.11.255.254249.11.255.255262,142
68249.12.0.0/14249.12.0.1 to 249.15.255.254249.15.255.255262,142
69249.16.0.0/14249.16.0.1 to 249.19.255.254249.19.255.255262,142
70249.20.0.0/14249.20.0.1 to 249.23.255.254249.23.255.255262,142
71249.24.0.0/14249.24.0.1 to 249.27.255.254249.27.255.255262,142
72249.28.0.0/14249.28.0.1 to 249.31.255.254249.31.255.255262,142
73249.32.0.0/14249.32.0.1 to 249.35.255.254249.35.255.255262,142
74249.36.0.0/14249.36.0.1 to 249.39.255.254249.39.255.255262,142
75249.40.0.0/14249.40.0.1 to 249.43.255.254249.43.255.255262,142
76249.44.0.0/14249.44.0.1 to 249.47.255.254249.47.255.255262,142
77249.48.0.0/14249.48.0.1 to 249.51.255.254249.51.255.255262,142
78249.52.0.0/14249.52.0.1 to 249.55.255.254249.55.255.255262,142
79249.56.0.0/14249.56.0.1 to 249.59.255.254249.59.255.255262,142
80249.60.0.0/14249.60.0.1 to 249.63.255.254249.63.255.255262,142
81249.64.0.0/14249.64.0.1 to 249.67.255.254249.67.255.255262,142
82249.68.0.0/14249.68.0.1 to 249.71.255.254249.71.255.255262,142
83249.72.0.0/14249.72.0.1 to 249.75.255.254249.75.255.255262,142
84249.76.0.0/14249.76.0.1 to 249.79.255.254249.79.255.255262,142
85249.80.0.0/14249.80.0.1 to 249.83.255.254249.83.255.255262,142
86249.84.0.0/14249.84.0.1 to 249.87.255.254249.87.255.255262,142
87249.88.0.0/14249.88.0.1 to 249.91.255.254249.91.255.255262,142
88249.92.0.0/14249.92.0.1 to 249.95.255.254249.95.255.255262,142
89249.96.0.0/14249.96.0.1 to 249.99.255.254249.99.255.255262,142
90249.100.0.0/14249.100.0.1 to 249.103.255.254249.103.255.255262,142
91249.104.0.0/14249.104.0.1 to 249.107.255.254249.107.255.255262,142
92249.108.0.0/14249.108.0.1 to 249.111.255.254249.111.255.255262,142
93249.112.0.0/14249.112.0.1 to 249.115.255.254249.115.255.255262,142
94249.116.0.0/14249.116.0.1 to 249.119.255.254249.119.255.255262,142
95249.120.0.0/14249.120.0.1 to 249.123.255.254249.123.255.255262,142
96249.124.0.0/14249.124.0.1 to 249.127.255.254249.127.255.255262,142
97249.128.0.0/14249.128.0.1 to 249.131.255.254249.131.255.255262,142
98249.132.0.0/14249.132.0.1 to 249.135.255.254249.135.255.255262,142
99249.136.0.0/14249.136.0.1 to 249.139.255.254249.139.255.255262,142
100249.140.0.0/14249.140.0.1 to 249.143.255.254249.143.255.255262,142
101249.144.0.0/14249.144.0.1 to 249.147.255.254249.147.255.255262,142
102249.148.0.0/14249.148.0.1 to 249.151.255.254249.151.255.255262,142
103249.152.0.0/14249.152.0.1 to 249.155.255.254249.155.255.255262,142
104249.156.0.0/14249.156.0.1 to 249.159.255.254249.159.255.255262,142
105249.160.0.0/14249.160.0.1 to 249.163.255.254249.163.255.255262,142
106249.164.0.0/14249.164.0.1 to 249.167.255.254249.167.255.255262,142
107249.168.0.0/14249.168.0.1 to 249.171.255.254249.171.255.255262,142
108249.172.0.0/14249.172.0.1 to 249.175.255.254249.175.255.255262,142
109249.176.0.0/14249.176.0.1 to 249.179.255.254249.179.255.255262,142
110249.180.0.0/14249.180.0.1 to 249.183.255.254249.183.255.255262,142
111249.184.0.0/14249.184.0.1 to 249.187.255.254249.187.255.255262,142
112249.188.0.0/14249.188.0.1 to 249.191.255.254249.191.255.255262,142
113249.192.0.0/14249.192.0.1 to 249.195.255.254249.195.255.255262,142
114249.196.0.0/14249.196.0.1 to 249.199.255.254249.199.255.255262,142
115249.200.0.0/14249.200.0.1 to 249.203.255.254249.203.255.255262,142
116249.204.0.0/14249.204.0.1 to 249.207.255.254249.207.255.255262,142
117249.208.0.0/14249.208.0.1 to 249.211.255.254249.211.255.255262,142
118249.212.0.0/14249.212.0.1 to 249.215.255.254249.215.255.255262,142
119249.216.0.0/14249.216.0.1 to 249.219.255.254249.219.255.255262,142
120249.220.0.0/14249.220.0.1 to 249.223.255.254249.223.255.255262,142
121249.224.0.0/14249.224.0.1 to 249.227.255.254249.227.255.255262,142
122249.228.0.0/14249.228.0.1 to 249.231.255.254249.231.255.255262,142
123249.232.0.0/14249.232.0.1 to 249.235.255.254249.235.255.255262,142
124249.236.0.0/14249.236.0.1 to 249.239.255.254249.239.255.255262,142
125249.240.0.0/14249.240.0.1 to 249.243.255.254249.243.255.255262,142
126249.244.0.0/14249.244.0.1 to 249.247.255.254249.247.255.255262,142
127249.248.0.0/14249.248.0.1 to 249.251.255.254249.251.255.255262,142
128249.252.0.0/14249.252.0.1 to 249.255.255.254249.255.255.255262,142

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.