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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.

Network245.32.167.0/24
Usable hosts254
Subnet mask255.255.255.0
Addresses256
Network address
245.32.167.0
Broadcast address
245.32.167.255
First usable
245.32.167.1
Last usable
245.32.167.254
Usable hosts
254 (256 less the network and broadcast addresses)
Subnet mask
255.255.255.0
Wildcard mask
0.0.0.255 (Cisco ACLs, OSPF)
Prefix length
/24
Type
Reserved 240.0.0.0/4
Future use; not usable on most systems
Old class
E (reserved)
As numbers
Hex F520A700 · Integer 4112557824 to 4112558079
Reverse DNS zone
167.32.245.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11110101.00100000.10100111..00000000245.32.167.0
Subnet mask11111111.11111111.11111111..00000000255.255.255.0
Network11110101.00100000.10100111..00000000245.32.167.0
Broadcast11110101.00100000.10100111..11111111245.32.167.255
Split into smaller subnets/30
/25 (2)/26 (4)/27 (8)/28 (16)/29 (32)/30 (64)/31 (128)/32 (256)

245.32.167.0/24 makes 64 subnets of /30.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1245.32.167.0/30245.32.167.1 to 245.32.167.2245.32.167.32
2245.32.167.4/30245.32.167.5 to 245.32.167.6245.32.167.72
3245.32.167.8/30245.32.167.9 to 245.32.167.10245.32.167.112
4245.32.167.12/30245.32.167.13 to 245.32.167.14245.32.167.152
5245.32.167.16/30245.32.167.17 to 245.32.167.18245.32.167.192
6245.32.167.20/30245.32.167.21 to 245.32.167.22245.32.167.232
7245.32.167.24/30245.32.167.25 to 245.32.167.26245.32.167.272
8245.32.167.28/30245.32.167.29 to 245.32.167.30245.32.167.312
9245.32.167.32/30245.32.167.33 to 245.32.167.34245.32.167.352
10245.32.167.36/30245.32.167.37 to 245.32.167.38245.32.167.392
11245.32.167.40/30245.32.167.41 to 245.32.167.42245.32.167.432
12245.32.167.44/30245.32.167.45 to 245.32.167.46245.32.167.472
13245.32.167.48/30245.32.167.49 to 245.32.167.50245.32.167.512
14245.32.167.52/30245.32.167.53 to 245.32.167.54245.32.167.552
15245.32.167.56/30245.32.167.57 to 245.32.167.58245.32.167.592
16245.32.167.60/30245.32.167.61 to 245.32.167.62245.32.167.632
17245.32.167.64/30245.32.167.65 to 245.32.167.66245.32.167.672
18245.32.167.68/30245.32.167.69 to 245.32.167.70245.32.167.712
19245.32.167.72/30245.32.167.73 to 245.32.167.74245.32.167.752
20245.32.167.76/30245.32.167.77 to 245.32.167.78245.32.167.792
21245.32.167.80/30245.32.167.81 to 245.32.167.82245.32.167.832
22245.32.167.84/30245.32.167.85 to 245.32.167.86245.32.167.872
23245.32.167.88/30245.32.167.89 to 245.32.167.90245.32.167.912
24245.32.167.92/30245.32.167.93 to 245.32.167.94245.32.167.952
25245.32.167.96/30245.32.167.97 to 245.32.167.98245.32.167.992
26245.32.167.100/30245.32.167.101 to 245.32.167.102245.32.167.1032
27245.32.167.104/30245.32.167.105 to 245.32.167.106245.32.167.1072
28245.32.167.108/30245.32.167.109 to 245.32.167.110245.32.167.1112
29245.32.167.112/30245.32.167.113 to 245.32.167.114245.32.167.1152
30245.32.167.116/30245.32.167.117 to 245.32.167.118245.32.167.1192
31245.32.167.120/30245.32.167.121 to 245.32.167.122245.32.167.1232
32245.32.167.124/30245.32.167.125 to 245.32.167.126245.32.167.1272
33245.32.167.128/30245.32.167.129 to 245.32.167.130245.32.167.1312
34245.32.167.132/30245.32.167.133 to 245.32.167.134245.32.167.1352
35245.32.167.136/30245.32.167.137 to 245.32.167.138245.32.167.1392
36245.32.167.140/30245.32.167.141 to 245.32.167.142245.32.167.1432
37245.32.167.144/30245.32.167.145 to 245.32.167.146245.32.167.1472
38245.32.167.148/30245.32.167.149 to 245.32.167.150245.32.167.1512
39245.32.167.152/30245.32.167.153 to 245.32.167.154245.32.167.1552
40245.32.167.156/30245.32.167.157 to 245.32.167.158245.32.167.1592
41245.32.167.160/30245.32.167.161 to 245.32.167.162245.32.167.1632
42245.32.167.164/30245.32.167.165 to 245.32.167.166245.32.167.1672
43245.32.167.168/30245.32.167.169 to 245.32.167.170245.32.167.1712
44245.32.167.172/30245.32.167.173 to 245.32.167.174245.32.167.1752
45245.32.167.176/30245.32.167.177 to 245.32.167.178245.32.167.1792
46245.32.167.180/30245.32.167.181 to 245.32.167.182245.32.167.1832
47245.32.167.184/30245.32.167.185 to 245.32.167.186245.32.167.1872
48245.32.167.188/30245.32.167.189 to 245.32.167.190245.32.167.1912
49245.32.167.192/30245.32.167.193 to 245.32.167.194245.32.167.1952
50245.32.167.196/30245.32.167.197 to 245.32.167.198245.32.167.1992
51245.32.167.200/30245.32.167.201 to 245.32.167.202245.32.167.2032
52245.32.167.204/30245.32.167.205 to 245.32.167.206245.32.167.2072
53245.32.167.208/30245.32.167.209 to 245.32.167.210245.32.167.2112
54245.32.167.212/30245.32.167.213 to 245.32.167.214245.32.167.2152
55245.32.167.216/30245.32.167.217 to 245.32.167.218245.32.167.2192
56245.32.167.220/30245.32.167.221 to 245.32.167.222245.32.167.2232
57245.32.167.224/30245.32.167.225 to 245.32.167.226245.32.167.2272
58245.32.167.228/30245.32.167.229 to 245.32.167.230245.32.167.2312
59245.32.167.232/30245.32.167.233 to 245.32.167.234245.32.167.2352
60245.32.167.236/30245.32.167.237 to 245.32.167.238245.32.167.2392
61245.32.167.240/30245.32.167.241 to 245.32.167.242245.32.167.2432
62245.32.167.244/30245.32.167.245 to 245.32.167.246245.32.167.2472
63245.32.167.248/30245.32.167.249 to 245.32.167.250245.32.167.2512
64245.32.167.252/30245.32.167.253 to 245.32.167.254245.32.167.2552

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.