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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.

Network242.232.80.0/22
Usable hosts1,022
Subnet mask255.255.252.0
Addresses1,024
Network address
242.232.80.0
Broadcast address
242.232.83.255
First usable
242.232.80.1
Last usable
242.232.83.254
Usable hosts
1,022 (1,024 less the network and broadcast addresses)
Subnet mask
255.255.252.0
Wildcard mask
0.0.3.255 (Cisco ACLs, OSPF)
Prefix length
/22
Type
Reserved 240.0.0.0/4
Future use; not usable on most systems
Old class
E (reserved)
As numbers
Hex F2E85000 · Integer 4075311104 to 4075312127
Reverse DNS zones
80.232.242.in-addr.arpa
81.232.242.in-addr.arpa
82.232.242.in-addr.arpa
83.232.242.in-addr.arpa
/22 is not on a 8-bit boundary, so it takes 4 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11110010.11101000.01010000.00000000242.232.80.0
Subnet mask11111111.11111111.11111100.00000000255.255.252.0
Network11110010.11101000.01010000.00000000242.232.80.0
Broadcast11110010.11101000.01010011.11111111242.232.83.255
Split into smaller subnets/28
/23 (2)/24 (4)/25 (8)/26 (16)/27 (32)/28 (64)/29 (128)/30 (256)/31 (512)/32 (1,024)

242.232.80.0/22 makes 64 subnets of /28.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1242.232.80.0/28242.232.80.1 to 242.232.80.14242.232.80.1514
2242.232.80.16/28242.232.80.17 to 242.232.80.30242.232.80.3114
3242.232.80.32/28242.232.80.33 to 242.232.80.46242.232.80.4714
4242.232.80.48/28242.232.80.49 to 242.232.80.62242.232.80.6314
5242.232.80.64/28242.232.80.65 to 242.232.80.78242.232.80.7914
6242.232.80.80/28242.232.80.81 to 242.232.80.94242.232.80.9514
7242.232.80.96/28242.232.80.97 to 242.232.80.110242.232.80.11114
8242.232.80.112/28242.232.80.113 to 242.232.80.126242.232.80.12714
9242.232.80.128/28242.232.80.129 to 242.232.80.142242.232.80.14314
10242.232.80.144/28242.232.80.145 to 242.232.80.158242.232.80.15914
11242.232.80.160/28242.232.80.161 to 242.232.80.174242.232.80.17514
12242.232.80.176/28242.232.80.177 to 242.232.80.190242.232.80.19114
13242.232.80.192/28242.232.80.193 to 242.232.80.206242.232.80.20714
14242.232.80.208/28242.232.80.209 to 242.232.80.222242.232.80.22314
15242.232.80.224/28242.232.80.225 to 242.232.80.238242.232.80.23914
16242.232.80.240/28242.232.80.241 to 242.232.80.254242.232.80.25514
17242.232.81.0/28242.232.81.1 to 242.232.81.14242.232.81.1514
18242.232.81.16/28242.232.81.17 to 242.232.81.30242.232.81.3114
19242.232.81.32/28242.232.81.33 to 242.232.81.46242.232.81.4714
20242.232.81.48/28242.232.81.49 to 242.232.81.62242.232.81.6314
21242.232.81.64/28242.232.81.65 to 242.232.81.78242.232.81.7914
22242.232.81.80/28242.232.81.81 to 242.232.81.94242.232.81.9514
23242.232.81.96/28242.232.81.97 to 242.232.81.110242.232.81.11114
24242.232.81.112/28242.232.81.113 to 242.232.81.126242.232.81.12714
25242.232.81.128/28242.232.81.129 to 242.232.81.142242.232.81.14314
26242.232.81.144/28242.232.81.145 to 242.232.81.158242.232.81.15914
27242.232.81.160/28242.232.81.161 to 242.232.81.174242.232.81.17514
28242.232.81.176/28242.232.81.177 to 242.232.81.190242.232.81.19114
29242.232.81.192/28242.232.81.193 to 242.232.81.206242.232.81.20714
30242.232.81.208/28242.232.81.209 to 242.232.81.222242.232.81.22314
31242.232.81.224/28242.232.81.225 to 242.232.81.238242.232.81.23914
32242.232.81.240/28242.232.81.241 to 242.232.81.254242.232.81.25514
33242.232.82.0/28242.232.82.1 to 242.232.82.14242.232.82.1514
34242.232.82.16/28242.232.82.17 to 242.232.82.30242.232.82.3114
35242.232.82.32/28242.232.82.33 to 242.232.82.46242.232.82.4714
36242.232.82.48/28242.232.82.49 to 242.232.82.62242.232.82.6314
37242.232.82.64/28242.232.82.65 to 242.232.82.78242.232.82.7914
38242.232.82.80/28242.232.82.81 to 242.232.82.94242.232.82.9514
39242.232.82.96/28242.232.82.97 to 242.232.82.110242.232.82.11114
40242.232.82.112/28242.232.82.113 to 242.232.82.126242.232.82.12714
41242.232.82.128/28242.232.82.129 to 242.232.82.142242.232.82.14314
42242.232.82.144/28242.232.82.145 to 242.232.82.158242.232.82.15914
43242.232.82.160/28242.232.82.161 to 242.232.82.174242.232.82.17514
44242.232.82.176/28242.232.82.177 to 242.232.82.190242.232.82.19114
45242.232.82.192/28242.232.82.193 to 242.232.82.206242.232.82.20714
46242.232.82.208/28242.232.82.209 to 242.232.82.222242.232.82.22314
47242.232.82.224/28242.232.82.225 to 242.232.82.238242.232.82.23914
48242.232.82.240/28242.232.82.241 to 242.232.82.254242.232.82.25514
49242.232.83.0/28242.232.83.1 to 242.232.83.14242.232.83.1514
50242.232.83.16/28242.232.83.17 to 242.232.83.30242.232.83.3114
51242.232.83.32/28242.232.83.33 to 242.232.83.46242.232.83.4714
52242.232.83.48/28242.232.83.49 to 242.232.83.62242.232.83.6314
53242.232.83.64/28242.232.83.65 to 242.232.83.78242.232.83.7914
54242.232.83.80/28242.232.83.81 to 242.232.83.94242.232.83.9514
55242.232.83.96/28242.232.83.97 to 242.232.83.110242.232.83.11114
56242.232.83.112/28242.232.83.113 to 242.232.83.126242.232.83.12714
57242.232.83.128/28242.232.83.129 to 242.232.83.142242.232.83.14314
58242.232.83.144/28242.232.83.145 to 242.232.83.158242.232.83.15914
59242.232.83.160/28242.232.83.161 to 242.232.83.174242.232.83.17514
60242.232.83.176/28242.232.83.177 to 242.232.83.190242.232.83.19114
61242.232.83.192/28242.232.83.193 to 242.232.83.206242.232.83.20714
62242.232.83.208/28242.232.83.209 to 242.232.83.222242.232.83.22314
63242.232.83.224/28242.232.83.225 to 242.232.83.238242.232.83.23914
64242.232.83.240/28242.232.83.241 to 242.232.83.254242.232.83.25514

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.