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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.

Network210.167.0.0/16
Usable hosts65,534
Subnet mask255.255.0.0
Addresses65,536
Network address
210.167.0.0
Broadcast address
210.167.255.255
First usable
210.167.0.1
Last usable
210.167.255.254
Usable hosts
65,534 (65,536 less the network and broadcast addresses)
Subnet mask
255.255.0.0
Wildcard mask
0.0.255.255 (Cisco ACLs, OSPF)
Prefix length
/16
Type
Public public
Old class
C (default /24)
As numbers
Hex D2A70000 · Integer 3534159872 to 3534225407
Reverse DNS zone
167.210.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11010010.10100111..00000000.00000000210.167.0.0
Subnet mask11111111.11111111..00000000.00000000255.255.0.0
Network11010010.10100111..00000000.00000000210.167.0.0
Broadcast11010010.10100111..11111111.11111111210.167.255.255
Split into smaller subnets/22
/17 (2)/18 (4)/19 (8)/20 (16)/21 (32)/22 (64)/23 (128)/24 (256)/25 (512)/26 (1,024)/27 (2,048)/28 (4,096)

210.167.0.0/16 makes 64 subnets of /22.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1210.167.0.0/22210.167.0.1 to 210.167.3.254210.167.3.2551,022
2210.167.4.0/22210.167.4.1 to 210.167.7.254210.167.7.2551,022
3210.167.8.0/22210.167.8.1 to 210.167.11.254210.167.11.2551,022
4210.167.12.0/22210.167.12.1 to 210.167.15.254210.167.15.2551,022
5210.167.16.0/22210.167.16.1 to 210.167.19.254210.167.19.2551,022
6210.167.20.0/22210.167.20.1 to 210.167.23.254210.167.23.2551,022
7210.167.24.0/22210.167.24.1 to 210.167.27.254210.167.27.2551,022
8210.167.28.0/22210.167.28.1 to 210.167.31.254210.167.31.2551,022
9210.167.32.0/22210.167.32.1 to 210.167.35.254210.167.35.2551,022
10210.167.36.0/22210.167.36.1 to 210.167.39.254210.167.39.2551,022
11210.167.40.0/22210.167.40.1 to 210.167.43.254210.167.43.2551,022
12210.167.44.0/22210.167.44.1 to 210.167.47.254210.167.47.2551,022
13210.167.48.0/22210.167.48.1 to 210.167.51.254210.167.51.2551,022
14210.167.52.0/22210.167.52.1 to 210.167.55.254210.167.55.2551,022
15210.167.56.0/22210.167.56.1 to 210.167.59.254210.167.59.2551,022
16210.167.60.0/22210.167.60.1 to 210.167.63.254210.167.63.2551,022
17210.167.64.0/22210.167.64.1 to 210.167.67.254210.167.67.2551,022
18210.167.68.0/22210.167.68.1 to 210.167.71.254210.167.71.2551,022
19210.167.72.0/22210.167.72.1 to 210.167.75.254210.167.75.2551,022
20210.167.76.0/22210.167.76.1 to 210.167.79.254210.167.79.2551,022
21210.167.80.0/22210.167.80.1 to 210.167.83.254210.167.83.2551,022
22210.167.84.0/22210.167.84.1 to 210.167.87.254210.167.87.2551,022
23210.167.88.0/22210.167.88.1 to 210.167.91.254210.167.91.2551,022
24210.167.92.0/22210.167.92.1 to 210.167.95.254210.167.95.2551,022
25210.167.96.0/22210.167.96.1 to 210.167.99.254210.167.99.2551,022
26210.167.100.0/22210.167.100.1 to 210.167.103.254210.167.103.2551,022
27210.167.104.0/22210.167.104.1 to 210.167.107.254210.167.107.2551,022
28210.167.108.0/22210.167.108.1 to 210.167.111.254210.167.111.2551,022
29210.167.112.0/22210.167.112.1 to 210.167.115.254210.167.115.2551,022
30210.167.116.0/22210.167.116.1 to 210.167.119.254210.167.119.2551,022
31210.167.120.0/22210.167.120.1 to 210.167.123.254210.167.123.2551,022
32210.167.124.0/22210.167.124.1 to 210.167.127.254210.167.127.2551,022
33210.167.128.0/22210.167.128.1 to 210.167.131.254210.167.131.2551,022
34210.167.132.0/22210.167.132.1 to 210.167.135.254210.167.135.2551,022
35210.167.136.0/22210.167.136.1 to 210.167.139.254210.167.139.2551,022
36210.167.140.0/22210.167.140.1 to 210.167.143.254210.167.143.2551,022
37210.167.144.0/22210.167.144.1 to 210.167.147.254210.167.147.2551,022
38210.167.148.0/22210.167.148.1 to 210.167.151.254210.167.151.2551,022
39210.167.152.0/22210.167.152.1 to 210.167.155.254210.167.155.2551,022
40210.167.156.0/22210.167.156.1 to 210.167.159.254210.167.159.2551,022
41210.167.160.0/22210.167.160.1 to 210.167.163.254210.167.163.2551,022
42210.167.164.0/22210.167.164.1 to 210.167.167.254210.167.167.2551,022
43210.167.168.0/22210.167.168.1 to 210.167.171.254210.167.171.2551,022
44210.167.172.0/22210.167.172.1 to 210.167.175.254210.167.175.2551,022
45210.167.176.0/22210.167.176.1 to 210.167.179.254210.167.179.2551,022
46210.167.180.0/22210.167.180.1 to 210.167.183.254210.167.183.2551,022
47210.167.184.0/22210.167.184.1 to 210.167.187.254210.167.187.2551,022
48210.167.188.0/22210.167.188.1 to 210.167.191.254210.167.191.2551,022
49210.167.192.0/22210.167.192.1 to 210.167.195.254210.167.195.2551,022
50210.167.196.0/22210.167.196.1 to 210.167.199.254210.167.199.2551,022
51210.167.200.0/22210.167.200.1 to 210.167.203.254210.167.203.2551,022
52210.167.204.0/22210.167.204.1 to 210.167.207.254210.167.207.2551,022
53210.167.208.0/22210.167.208.1 to 210.167.211.254210.167.211.2551,022
54210.167.212.0/22210.167.212.1 to 210.167.215.254210.167.215.2551,022
55210.167.216.0/22210.167.216.1 to 210.167.219.254210.167.219.2551,022
56210.167.220.0/22210.167.220.1 to 210.167.223.254210.167.223.2551,022
57210.167.224.0/22210.167.224.1 to 210.167.227.254210.167.227.2551,022
58210.167.228.0/22210.167.228.1 to 210.167.231.254210.167.231.2551,022
59210.167.232.0/22210.167.232.1 to 210.167.235.254210.167.235.2551,022
60210.167.236.0/22210.167.236.1 to 210.167.239.254210.167.239.2551,022
61210.167.240.0/22210.167.240.1 to 210.167.243.254210.167.243.2551,022
62210.167.244.0/22210.167.244.1 to 210.167.247.254210.167.247.2551,022
63210.167.248.0/22210.167.248.1 to 210.167.251.254210.167.251.2551,022
64210.167.252.0/22210.167.252.1 to 210.167.255.254210.167.255.2551,022

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.