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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.

Network33.2.44.0/22
Usable hosts1,022
Subnet mask255.255.252.0
Addresses1,024
Network address
33.2.44.0
Broadcast address
33.2.47.255
First usable
33.2.44.1
Last usable
33.2.47.254
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 21022C00 · Integer 553790464 to 553791487
Reverse DNS zones
44.2.33.in-addr.arpa
45.2.33.in-addr.arpa
46.2.33.in-addr.arpa
47.2.33.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
Address00100001.00000010.00101100.0000000033.2.44.0
Subnet mask11111111.11111111.11111100.00000000255.255.252.0
Network00100001.00000010.00101100.0000000033.2.44.0
Broadcast00100001.00000010.00101111.1111111133.2.47.255
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)

33.2.44.0/22 makes 64 subnets of /28.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
133.2.44.0/2833.2.44.1 to 33.2.44.1433.2.44.1514
233.2.44.16/2833.2.44.17 to 33.2.44.3033.2.44.3114
333.2.44.32/2833.2.44.33 to 33.2.44.4633.2.44.4714
433.2.44.48/2833.2.44.49 to 33.2.44.6233.2.44.6314
533.2.44.64/2833.2.44.65 to 33.2.44.7833.2.44.7914
633.2.44.80/2833.2.44.81 to 33.2.44.9433.2.44.9514
733.2.44.96/2833.2.44.97 to 33.2.44.11033.2.44.11114
833.2.44.112/2833.2.44.113 to 33.2.44.12633.2.44.12714
933.2.44.128/2833.2.44.129 to 33.2.44.14233.2.44.14314
1033.2.44.144/2833.2.44.145 to 33.2.44.15833.2.44.15914
1133.2.44.160/2833.2.44.161 to 33.2.44.17433.2.44.17514
1233.2.44.176/2833.2.44.177 to 33.2.44.19033.2.44.19114
1333.2.44.192/2833.2.44.193 to 33.2.44.20633.2.44.20714
1433.2.44.208/2833.2.44.209 to 33.2.44.22233.2.44.22314
1533.2.44.224/2833.2.44.225 to 33.2.44.23833.2.44.23914
1633.2.44.240/2833.2.44.241 to 33.2.44.25433.2.44.25514
1733.2.45.0/2833.2.45.1 to 33.2.45.1433.2.45.1514
1833.2.45.16/2833.2.45.17 to 33.2.45.3033.2.45.3114
1933.2.45.32/2833.2.45.33 to 33.2.45.4633.2.45.4714
2033.2.45.48/2833.2.45.49 to 33.2.45.6233.2.45.6314
2133.2.45.64/2833.2.45.65 to 33.2.45.7833.2.45.7914
2233.2.45.80/2833.2.45.81 to 33.2.45.9433.2.45.9514
2333.2.45.96/2833.2.45.97 to 33.2.45.11033.2.45.11114
2433.2.45.112/2833.2.45.113 to 33.2.45.12633.2.45.12714
2533.2.45.128/2833.2.45.129 to 33.2.45.14233.2.45.14314
2633.2.45.144/2833.2.45.145 to 33.2.45.15833.2.45.15914
2733.2.45.160/2833.2.45.161 to 33.2.45.17433.2.45.17514
2833.2.45.176/2833.2.45.177 to 33.2.45.19033.2.45.19114
2933.2.45.192/2833.2.45.193 to 33.2.45.20633.2.45.20714
3033.2.45.208/2833.2.45.209 to 33.2.45.22233.2.45.22314
3133.2.45.224/2833.2.45.225 to 33.2.45.23833.2.45.23914
3233.2.45.240/2833.2.45.241 to 33.2.45.25433.2.45.25514
3333.2.46.0/2833.2.46.1 to 33.2.46.1433.2.46.1514
3433.2.46.16/2833.2.46.17 to 33.2.46.3033.2.46.3114
3533.2.46.32/2833.2.46.33 to 33.2.46.4633.2.46.4714
3633.2.46.48/2833.2.46.49 to 33.2.46.6233.2.46.6314
3733.2.46.64/2833.2.46.65 to 33.2.46.7833.2.46.7914
3833.2.46.80/2833.2.46.81 to 33.2.46.9433.2.46.9514
3933.2.46.96/2833.2.46.97 to 33.2.46.11033.2.46.11114
4033.2.46.112/2833.2.46.113 to 33.2.46.12633.2.46.12714
4133.2.46.128/2833.2.46.129 to 33.2.46.14233.2.46.14314
4233.2.46.144/2833.2.46.145 to 33.2.46.15833.2.46.15914
4333.2.46.160/2833.2.46.161 to 33.2.46.17433.2.46.17514
4433.2.46.176/2833.2.46.177 to 33.2.46.19033.2.46.19114
4533.2.46.192/2833.2.46.193 to 33.2.46.20633.2.46.20714
4633.2.46.208/2833.2.46.209 to 33.2.46.22233.2.46.22314
4733.2.46.224/2833.2.46.225 to 33.2.46.23833.2.46.23914
4833.2.46.240/2833.2.46.241 to 33.2.46.25433.2.46.25514
4933.2.47.0/2833.2.47.1 to 33.2.47.1433.2.47.1514
5033.2.47.16/2833.2.47.17 to 33.2.47.3033.2.47.3114
5133.2.47.32/2833.2.47.33 to 33.2.47.4633.2.47.4714
5233.2.47.48/2833.2.47.49 to 33.2.47.6233.2.47.6314
5333.2.47.64/2833.2.47.65 to 33.2.47.7833.2.47.7914
5433.2.47.80/2833.2.47.81 to 33.2.47.9433.2.47.9514
5533.2.47.96/2833.2.47.97 to 33.2.47.11033.2.47.11114
5633.2.47.112/2833.2.47.113 to 33.2.47.12633.2.47.12714
5733.2.47.128/2833.2.47.129 to 33.2.47.14233.2.47.14314
5833.2.47.144/2833.2.47.145 to 33.2.47.15833.2.47.15914
5933.2.47.160/2833.2.47.161 to 33.2.47.17433.2.47.17514
6033.2.47.176/2833.2.47.177 to 33.2.47.19033.2.47.19114
6133.2.47.192/2833.2.47.193 to 33.2.47.20633.2.47.20714
6233.2.47.208/2833.2.47.209 to 33.2.47.22233.2.47.22314
6333.2.47.224/2833.2.47.225 to 33.2.47.23833.2.47.23914
6433.2.47.240/2833.2.47.241 to 33.2.47.25433.2.47.25514

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.