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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.

Network24.65.68.0/22
Usable hosts1,022
Subnet mask255.255.252.0
Addresses1,024
Network address
24.65.68.0
Broadcast address
24.65.71.255
First usable
24.65.68.1
Last usable
24.65.71.254
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
Public public
Old class
A (default /8)
As numbers
Hex 18414400 · Integer 406930432 to 406931455
Reverse DNS zones
68.65.24.in-addr.arpa
69.65.24.in-addr.arpa
70.65.24.in-addr.arpa
71.65.24.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
Address00011000.01000001.01000100.0000000024.65.68.0
Subnet mask11111111.11111111.11111100.00000000255.255.252.0
Network00011000.01000001.01000100.0000000024.65.68.0
Broadcast00011000.01000001.01000111.1111111124.65.71.255
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)

24.65.68.0/22 makes 64 subnets of /28.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
124.65.68.0/2824.65.68.1 to 24.65.68.1424.65.68.1514
224.65.68.16/2824.65.68.17 to 24.65.68.3024.65.68.3114
324.65.68.32/2824.65.68.33 to 24.65.68.4624.65.68.4714
424.65.68.48/2824.65.68.49 to 24.65.68.6224.65.68.6314
524.65.68.64/2824.65.68.65 to 24.65.68.7824.65.68.7914
624.65.68.80/2824.65.68.81 to 24.65.68.9424.65.68.9514
724.65.68.96/2824.65.68.97 to 24.65.68.11024.65.68.11114
824.65.68.112/2824.65.68.113 to 24.65.68.12624.65.68.12714
924.65.68.128/2824.65.68.129 to 24.65.68.14224.65.68.14314
1024.65.68.144/2824.65.68.145 to 24.65.68.15824.65.68.15914
1124.65.68.160/2824.65.68.161 to 24.65.68.17424.65.68.17514
1224.65.68.176/2824.65.68.177 to 24.65.68.19024.65.68.19114
1324.65.68.192/2824.65.68.193 to 24.65.68.20624.65.68.20714
1424.65.68.208/2824.65.68.209 to 24.65.68.22224.65.68.22314
1524.65.68.224/2824.65.68.225 to 24.65.68.23824.65.68.23914
1624.65.68.240/2824.65.68.241 to 24.65.68.25424.65.68.25514
1724.65.69.0/2824.65.69.1 to 24.65.69.1424.65.69.1514
1824.65.69.16/2824.65.69.17 to 24.65.69.3024.65.69.3114
1924.65.69.32/2824.65.69.33 to 24.65.69.4624.65.69.4714
2024.65.69.48/2824.65.69.49 to 24.65.69.6224.65.69.6314
2124.65.69.64/2824.65.69.65 to 24.65.69.7824.65.69.7914
2224.65.69.80/2824.65.69.81 to 24.65.69.9424.65.69.9514
2324.65.69.96/2824.65.69.97 to 24.65.69.11024.65.69.11114
2424.65.69.112/2824.65.69.113 to 24.65.69.12624.65.69.12714
2524.65.69.128/2824.65.69.129 to 24.65.69.14224.65.69.14314
2624.65.69.144/2824.65.69.145 to 24.65.69.15824.65.69.15914
2724.65.69.160/2824.65.69.161 to 24.65.69.17424.65.69.17514
2824.65.69.176/2824.65.69.177 to 24.65.69.19024.65.69.19114
2924.65.69.192/2824.65.69.193 to 24.65.69.20624.65.69.20714
3024.65.69.208/2824.65.69.209 to 24.65.69.22224.65.69.22314
3124.65.69.224/2824.65.69.225 to 24.65.69.23824.65.69.23914
3224.65.69.240/2824.65.69.241 to 24.65.69.25424.65.69.25514
3324.65.70.0/2824.65.70.1 to 24.65.70.1424.65.70.1514
3424.65.70.16/2824.65.70.17 to 24.65.70.3024.65.70.3114
3524.65.70.32/2824.65.70.33 to 24.65.70.4624.65.70.4714
3624.65.70.48/2824.65.70.49 to 24.65.70.6224.65.70.6314
3724.65.70.64/2824.65.70.65 to 24.65.70.7824.65.70.7914
3824.65.70.80/2824.65.70.81 to 24.65.70.9424.65.70.9514
3924.65.70.96/2824.65.70.97 to 24.65.70.11024.65.70.11114
4024.65.70.112/2824.65.70.113 to 24.65.70.12624.65.70.12714
4124.65.70.128/2824.65.70.129 to 24.65.70.14224.65.70.14314
4224.65.70.144/2824.65.70.145 to 24.65.70.15824.65.70.15914
4324.65.70.160/2824.65.70.161 to 24.65.70.17424.65.70.17514
4424.65.70.176/2824.65.70.177 to 24.65.70.19024.65.70.19114
4524.65.70.192/2824.65.70.193 to 24.65.70.20624.65.70.20714
4624.65.70.208/2824.65.70.209 to 24.65.70.22224.65.70.22314
4724.65.70.224/2824.65.70.225 to 24.65.70.23824.65.70.23914
4824.65.70.240/2824.65.70.241 to 24.65.70.25424.65.70.25514
4924.65.71.0/2824.65.71.1 to 24.65.71.1424.65.71.1514
5024.65.71.16/2824.65.71.17 to 24.65.71.3024.65.71.3114
5124.65.71.32/2824.65.71.33 to 24.65.71.4624.65.71.4714
5224.65.71.48/2824.65.71.49 to 24.65.71.6224.65.71.6314
5324.65.71.64/2824.65.71.65 to 24.65.71.7824.65.71.7914
5424.65.71.80/2824.65.71.81 to 24.65.71.9424.65.71.9514
5524.65.71.96/2824.65.71.97 to 24.65.71.11024.65.71.11114
5624.65.71.112/2824.65.71.113 to 24.65.71.12624.65.71.12714
5724.65.71.128/2824.65.71.129 to 24.65.71.14224.65.71.14314
5824.65.71.144/2824.65.71.145 to 24.65.71.15824.65.71.15914
5924.65.71.160/2824.65.71.161 to 24.65.71.17424.65.71.17514
6024.65.71.176/2824.65.71.177 to 24.65.71.19024.65.71.19114
6124.65.71.192/2824.65.71.193 to 24.65.71.20624.65.71.20714
6224.65.71.208/2824.65.71.209 to 24.65.71.22224.65.71.22314
6324.65.71.224/2824.65.71.225 to 24.65.71.23824.65.71.23914
6424.65.71.240/2824.65.71.241 to 24.65.71.25424.65.71.25514

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.