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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.

Network51.2.232.0/22
Usable hosts1,022
Subnet mask255.255.252.0
Addresses1,024
Network address
51.2.232.0
Broadcast address
51.2.235.255
First usable
51.2.232.1
Last usable
51.2.235.254
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 3302E800 · Integer 855828480 to 855829503
Reverse DNS zones
232.2.51.in-addr.arpa
233.2.51.in-addr.arpa
234.2.51.in-addr.arpa
235.2.51.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
Address00110011.00000010.11101000.0000000051.2.232.0
Subnet mask11111111.11111111.11111100.00000000255.255.252.0
Network00110011.00000010.11101000.0000000051.2.232.0
Broadcast00110011.00000010.11101011.1111111151.2.235.255
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)

51.2.232.0/22 makes 64 subnets of /28.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
151.2.232.0/2851.2.232.1 to 51.2.232.1451.2.232.1514
251.2.232.16/2851.2.232.17 to 51.2.232.3051.2.232.3114
351.2.232.32/2851.2.232.33 to 51.2.232.4651.2.232.4714
451.2.232.48/2851.2.232.49 to 51.2.232.6251.2.232.6314
551.2.232.64/2851.2.232.65 to 51.2.232.7851.2.232.7914
651.2.232.80/2851.2.232.81 to 51.2.232.9451.2.232.9514
751.2.232.96/2851.2.232.97 to 51.2.232.11051.2.232.11114
851.2.232.112/2851.2.232.113 to 51.2.232.12651.2.232.12714
951.2.232.128/2851.2.232.129 to 51.2.232.14251.2.232.14314
1051.2.232.144/2851.2.232.145 to 51.2.232.15851.2.232.15914
1151.2.232.160/2851.2.232.161 to 51.2.232.17451.2.232.17514
1251.2.232.176/2851.2.232.177 to 51.2.232.19051.2.232.19114
1351.2.232.192/2851.2.232.193 to 51.2.232.20651.2.232.20714
1451.2.232.208/2851.2.232.209 to 51.2.232.22251.2.232.22314
1551.2.232.224/2851.2.232.225 to 51.2.232.23851.2.232.23914
1651.2.232.240/2851.2.232.241 to 51.2.232.25451.2.232.25514
1751.2.233.0/2851.2.233.1 to 51.2.233.1451.2.233.1514
1851.2.233.16/2851.2.233.17 to 51.2.233.3051.2.233.3114
1951.2.233.32/2851.2.233.33 to 51.2.233.4651.2.233.4714
2051.2.233.48/2851.2.233.49 to 51.2.233.6251.2.233.6314
2151.2.233.64/2851.2.233.65 to 51.2.233.7851.2.233.7914
2251.2.233.80/2851.2.233.81 to 51.2.233.9451.2.233.9514
2351.2.233.96/2851.2.233.97 to 51.2.233.11051.2.233.11114
2451.2.233.112/2851.2.233.113 to 51.2.233.12651.2.233.12714
2551.2.233.128/2851.2.233.129 to 51.2.233.14251.2.233.14314
2651.2.233.144/2851.2.233.145 to 51.2.233.15851.2.233.15914
2751.2.233.160/2851.2.233.161 to 51.2.233.17451.2.233.17514
2851.2.233.176/2851.2.233.177 to 51.2.233.19051.2.233.19114
2951.2.233.192/2851.2.233.193 to 51.2.233.20651.2.233.20714
3051.2.233.208/2851.2.233.209 to 51.2.233.22251.2.233.22314
3151.2.233.224/2851.2.233.225 to 51.2.233.23851.2.233.23914
3251.2.233.240/2851.2.233.241 to 51.2.233.25451.2.233.25514
3351.2.234.0/2851.2.234.1 to 51.2.234.1451.2.234.1514
3451.2.234.16/2851.2.234.17 to 51.2.234.3051.2.234.3114
3551.2.234.32/2851.2.234.33 to 51.2.234.4651.2.234.4714
3651.2.234.48/2851.2.234.49 to 51.2.234.6251.2.234.6314
3751.2.234.64/2851.2.234.65 to 51.2.234.7851.2.234.7914
3851.2.234.80/2851.2.234.81 to 51.2.234.9451.2.234.9514
3951.2.234.96/2851.2.234.97 to 51.2.234.11051.2.234.11114
4051.2.234.112/2851.2.234.113 to 51.2.234.12651.2.234.12714
4151.2.234.128/2851.2.234.129 to 51.2.234.14251.2.234.14314
4251.2.234.144/2851.2.234.145 to 51.2.234.15851.2.234.15914
4351.2.234.160/2851.2.234.161 to 51.2.234.17451.2.234.17514
4451.2.234.176/2851.2.234.177 to 51.2.234.19051.2.234.19114
4551.2.234.192/2851.2.234.193 to 51.2.234.20651.2.234.20714
4651.2.234.208/2851.2.234.209 to 51.2.234.22251.2.234.22314
4751.2.234.224/2851.2.234.225 to 51.2.234.23851.2.234.23914
4851.2.234.240/2851.2.234.241 to 51.2.234.25451.2.234.25514
4951.2.235.0/2851.2.235.1 to 51.2.235.1451.2.235.1514
5051.2.235.16/2851.2.235.17 to 51.2.235.3051.2.235.3114
5151.2.235.32/2851.2.235.33 to 51.2.235.4651.2.235.4714
5251.2.235.48/2851.2.235.49 to 51.2.235.6251.2.235.6314
5351.2.235.64/2851.2.235.65 to 51.2.235.7851.2.235.7914
5451.2.235.80/2851.2.235.81 to 51.2.235.9451.2.235.9514
5551.2.235.96/2851.2.235.97 to 51.2.235.11051.2.235.11114
5651.2.235.112/2851.2.235.113 to 51.2.235.12651.2.235.12714
5751.2.235.128/2851.2.235.129 to 51.2.235.14251.2.235.14314
5851.2.235.144/2851.2.235.145 to 51.2.235.15851.2.235.15914
5951.2.235.160/2851.2.235.161 to 51.2.235.17451.2.235.17514
6051.2.235.176/2851.2.235.177 to 51.2.235.19051.2.235.19114
6151.2.235.192/2851.2.235.193 to 51.2.235.20651.2.235.20714
6251.2.235.208/2851.2.235.209 to 51.2.235.22251.2.235.22314
6351.2.235.224/2851.2.235.225 to 51.2.235.23851.2.235.23914
6451.2.235.240/2851.2.235.241 to 51.2.235.25451.2.235.25514

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.