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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.

Network192.0.0.0/24
Usable hosts254
Subnet mask255.255.255.0
Addresses256
Network address
192.0.0.0
Broadcast address
192.0.0.255
First usable
192.0.0.1
Last usable
192.0.0.254
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
IETF protocol assignments 192.0.0.0/24
Special uses such as DS-Lite
Old class
C (default /24)
As numbers
Hex C0000000 · Integer 3221225472 to 3221225727
Reverse DNS zone
0.0.192.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11000000.00000000.00000000..00000000192.0.0.0
Subnet mask11111111.11111111.11111111..00000000255.255.255.0
Network11000000.00000000.00000000..00000000192.0.0.0
Broadcast11000000.00000000.00000000..11111111192.0.0.255
Split into smaller subnets/30
/25 (2)/26 (4)/27 (8)/28 (16)/29 (32)/30 (64)/31 (128)/32 (256)

192.0.0.0/24 makes 64 subnets of /30.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1192.0.0.0/30192.0.0.1 to 192.0.0.2192.0.0.32
2192.0.0.4/30192.0.0.5 to 192.0.0.6192.0.0.72
3192.0.0.8/30192.0.0.9 to 192.0.0.10192.0.0.112
4192.0.0.12/30192.0.0.13 to 192.0.0.14192.0.0.152
5192.0.0.16/30192.0.0.17 to 192.0.0.18192.0.0.192
6192.0.0.20/30192.0.0.21 to 192.0.0.22192.0.0.232
7192.0.0.24/30192.0.0.25 to 192.0.0.26192.0.0.272
8192.0.0.28/30192.0.0.29 to 192.0.0.30192.0.0.312
9192.0.0.32/30192.0.0.33 to 192.0.0.34192.0.0.352
10192.0.0.36/30192.0.0.37 to 192.0.0.38192.0.0.392
11192.0.0.40/30192.0.0.41 to 192.0.0.42192.0.0.432
12192.0.0.44/30192.0.0.45 to 192.0.0.46192.0.0.472
13192.0.0.48/30192.0.0.49 to 192.0.0.50192.0.0.512
14192.0.0.52/30192.0.0.53 to 192.0.0.54192.0.0.552
15192.0.0.56/30192.0.0.57 to 192.0.0.58192.0.0.592
16192.0.0.60/30192.0.0.61 to 192.0.0.62192.0.0.632
17192.0.0.64/30192.0.0.65 to 192.0.0.66192.0.0.672
18192.0.0.68/30192.0.0.69 to 192.0.0.70192.0.0.712
19192.0.0.72/30192.0.0.73 to 192.0.0.74192.0.0.752
20192.0.0.76/30192.0.0.77 to 192.0.0.78192.0.0.792
21192.0.0.80/30192.0.0.81 to 192.0.0.82192.0.0.832
22192.0.0.84/30192.0.0.85 to 192.0.0.86192.0.0.872
23192.0.0.88/30192.0.0.89 to 192.0.0.90192.0.0.912
24192.0.0.92/30192.0.0.93 to 192.0.0.94192.0.0.952
25192.0.0.96/30192.0.0.97 to 192.0.0.98192.0.0.992
26192.0.0.100/30192.0.0.101 to 192.0.0.102192.0.0.1032
27192.0.0.104/30192.0.0.105 to 192.0.0.106192.0.0.1072
28192.0.0.108/30192.0.0.109 to 192.0.0.110192.0.0.1112
29192.0.0.112/30192.0.0.113 to 192.0.0.114192.0.0.1152
30192.0.0.116/30192.0.0.117 to 192.0.0.118192.0.0.1192
31192.0.0.120/30192.0.0.121 to 192.0.0.122192.0.0.1232
32192.0.0.124/30192.0.0.125 to 192.0.0.126192.0.0.1272
33192.0.0.128/30192.0.0.129 to 192.0.0.130192.0.0.1312
34192.0.0.132/30192.0.0.133 to 192.0.0.134192.0.0.1352
35192.0.0.136/30192.0.0.137 to 192.0.0.138192.0.0.1392
36192.0.0.140/30192.0.0.141 to 192.0.0.142192.0.0.1432
37192.0.0.144/30192.0.0.145 to 192.0.0.146192.0.0.1472
38192.0.0.148/30192.0.0.149 to 192.0.0.150192.0.0.1512
39192.0.0.152/30192.0.0.153 to 192.0.0.154192.0.0.1552
40192.0.0.156/30192.0.0.157 to 192.0.0.158192.0.0.1592
41192.0.0.160/30192.0.0.161 to 192.0.0.162192.0.0.1632
42192.0.0.164/30192.0.0.165 to 192.0.0.166192.0.0.1672
43192.0.0.168/30192.0.0.169 to 192.0.0.170192.0.0.1712
44192.0.0.172/30192.0.0.173 to 192.0.0.174192.0.0.1752
45192.0.0.176/30192.0.0.177 to 192.0.0.178192.0.0.1792
46192.0.0.180/30192.0.0.181 to 192.0.0.182192.0.0.1832
47192.0.0.184/30192.0.0.185 to 192.0.0.186192.0.0.1872
48192.0.0.188/30192.0.0.189 to 192.0.0.190192.0.0.1912
49192.0.0.192/30192.0.0.193 to 192.0.0.194192.0.0.1952
50192.0.0.196/30192.0.0.197 to 192.0.0.198192.0.0.1992
51192.0.0.200/30192.0.0.201 to 192.0.0.202192.0.0.2032
52192.0.0.204/30192.0.0.205 to 192.0.0.206192.0.0.2072
53192.0.0.208/30192.0.0.209 to 192.0.0.210192.0.0.2112
54192.0.0.212/30192.0.0.213 to 192.0.0.214192.0.0.2152
55192.0.0.216/30192.0.0.217 to 192.0.0.218192.0.0.2192
56192.0.0.220/30192.0.0.221 to 192.0.0.222192.0.0.2232
57192.0.0.224/30192.0.0.225 to 192.0.0.226192.0.0.2272
58192.0.0.228/30192.0.0.229 to 192.0.0.230192.0.0.2312
59192.0.0.232/30192.0.0.233 to 192.0.0.234192.0.0.2352
60192.0.0.236/30192.0.0.237 to 192.0.0.238192.0.0.2392
61192.0.0.240/30192.0.0.241 to 192.0.0.242192.0.0.2432
62192.0.0.244/30192.0.0.245 to 192.0.0.246192.0.0.2472
63192.0.0.248/30192.0.0.249 to 192.0.0.250192.0.0.2512
64192.0.0.252/30192.0.0.253 to 192.0.0.254192.0.0.2552

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.