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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.

Network22.1.64.0/20
Usable hosts4,094
Subnet mask255.255.240.0
Addresses4,096
Network address
22.1.64.0
Broadcast address
22.1.79.255
First usable
22.1.64.1
Last usable
22.1.79.254
Usable hosts
4,094 (4,096 less the network and broadcast addresses)
Subnet mask
255.255.240.0
Wildcard mask
0.0.15.255 (Cisco ACLs, OSPF)
Prefix length
/20
Type
Public public
Old class
A (default /8)
As numbers
Hex 16014000 · Integer 369180672 to 369184767
Reverse DNS zones
64.1.22.in-addr.arpa
65.1.22.in-addr.arpa
66.1.22.in-addr.arpa
67.1.22.in-addr.arpa
68.1.22.in-addr.arpa
69.1.22.in-addr.arpa
70.1.22.in-addr.arpa
71.1.22.in-addr.arpa
72.1.22.in-addr.arpa
73.1.22.in-addr.arpa
74.1.22.in-addr.arpa
75.1.22.in-addr.arpa
76.1.22.in-addr.arpa
77.1.22.in-addr.arpa
78.1.22.in-addr.arpa
79.1.22.in-addr.arpa
/20 is not on a 8-bit boundary, so it takes 16 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00010110.00000001.01000000.0000000022.1.64.0
Subnet mask11111111.11111111.11110000.00000000255.255.240.0
Network00010110.00000001.01000000.0000000022.1.64.0
Broadcast00010110.00000001.01001111.1111111122.1.79.255
Split into smaller subnets/27
/21 (2)/22 (4)/23 (8)/24 (16)/25 (32)/26 (64)/27 (128)/28 (256)/29 (512)/30 (1,024)/31 (2,048)/32 (4,096)

22.1.64.0/20 makes 128 subnets of /27.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
122.1.64.0/2722.1.64.1 to 22.1.64.3022.1.64.3130
222.1.64.32/2722.1.64.33 to 22.1.64.6222.1.64.6330
322.1.64.64/2722.1.64.65 to 22.1.64.9422.1.64.9530
422.1.64.96/2722.1.64.97 to 22.1.64.12622.1.64.12730
522.1.64.128/2722.1.64.129 to 22.1.64.15822.1.64.15930
622.1.64.160/2722.1.64.161 to 22.1.64.19022.1.64.19130
722.1.64.192/2722.1.64.193 to 22.1.64.22222.1.64.22330
822.1.64.224/2722.1.64.225 to 22.1.64.25422.1.64.25530
922.1.65.0/2722.1.65.1 to 22.1.65.3022.1.65.3130
1022.1.65.32/2722.1.65.33 to 22.1.65.6222.1.65.6330
1122.1.65.64/2722.1.65.65 to 22.1.65.9422.1.65.9530
1222.1.65.96/2722.1.65.97 to 22.1.65.12622.1.65.12730
1322.1.65.128/2722.1.65.129 to 22.1.65.15822.1.65.15930
1422.1.65.160/2722.1.65.161 to 22.1.65.19022.1.65.19130
1522.1.65.192/2722.1.65.193 to 22.1.65.22222.1.65.22330
1622.1.65.224/2722.1.65.225 to 22.1.65.25422.1.65.25530
1722.1.66.0/2722.1.66.1 to 22.1.66.3022.1.66.3130
1822.1.66.32/2722.1.66.33 to 22.1.66.6222.1.66.6330
1922.1.66.64/2722.1.66.65 to 22.1.66.9422.1.66.9530
2022.1.66.96/2722.1.66.97 to 22.1.66.12622.1.66.12730
2122.1.66.128/2722.1.66.129 to 22.1.66.15822.1.66.15930
2222.1.66.160/2722.1.66.161 to 22.1.66.19022.1.66.19130
2322.1.66.192/2722.1.66.193 to 22.1.66.22222.1.66.22330
2422.1.66.224/2722.1.66.225 to 22.1.66.25422.1.66.25530
2522.1.67.0/2722.1.67.1 to 22.1.67.3022.1.67.3130
2622.1.67.32/2722.1.67.33 to 22.1.67.6222.1.67.6330
2722.1.67.64/2722.1.67.65 to 22.1.67.9422.1.67.9530
2822.1.67.96/2722.1.67.97 to 22.1.67.12622.1.67.12730
2922.1.67.128/2722.1.67.129 to 22.1.67.15822.1.67.15930
3022.1.67.160/2722.1.67.161 to 22.1.67.19022.1.67.19130
3122.1.67.192/2722.1.67.193 to 22.1.67.22222.1.67.22330
3222.1.67.224/2722.1.67.225 to 22.1.67.25422.1.67.25530
3322.1.68.0/2722.1.68.1 to 22.1.68.3022.1.68.3130
3422.1.68.32/2722.1.68.33 to 22.1.68.6222.1.68.6330
3522.1.68.64/2722.1.68.65 to 22.1.68.9422.1.68.9530
3622.1.68.96/2722.1.68.97 to 22.1.68.12622.1.68.12730
3722.1.68.128/2722.1.68.129 to 22.1.68.15822.1.68.15930
3822.1.68.160/2722.1.68.161 to 22.1.68.19022.1.68.19130
3922.1.68.192/2722.1.68.193 to 22.1.68.22222.1.68.22330
4022.1.68.224/2722.1.68.225 to 22.1.68.25422.1.68.25530
4122.1.69.0/2722.1.69.1 to 22.1.69.3022.1.69.3130
4222.1.69.32/2722.1.69.33 to 22.1.69.6222.1.69.6330
4322.1.69.64/2722.1.69.65 to 22.1.69.9422.1.69.9530
4422.1.69.96/2722.1.69.97 to 22.1.69.12622.1.69.12730
4522.1.69.128/2722.1.69.129 to 22.1.69.15822.1.69.15930
4622.1.69.160/2722.1.69.161 to 22.1.69.19022.1.69.19130
4722.1.69.192/2722.1.69.193 to 22.1.69.22222.1.69.22330
4822.1.69.224/2722.1.69.225 to 22.1.69.25422.1.69.25530
4922.1.70.0/2722.1.70.1 to 22.1.70.3022.1.70.3130
5022.1.70.32/2722.1.70.33 to 22.1.70.6222.1.70.6330
5122.1.70.64/2722.1.70.65 to 22.1.70.9422.1.70.9530
5222.1.70.96/2722.1.70.97 to 22.1.70.12622.1.70.12730
5322.1.70.128/2722.1.70.129 to 22.1.70.15822.1.70.15930
5422.1.70.160/2722.1.70.161 to 22.1.70.19022.1.70.19130
5522.1.70.192/2722.1.70.193 to 22.1.70.22222.1.70.22330
5622.1.70.224/2722.1.70.225 to 22.1.70.25422.1.70.25530
5722.1.71.0/2722.1.71.1 to 22.1.71.3022.1.71.3130
5822.1.71.32/2722.1.71.33 to 22.1.71.6222.1.71.6330
5922.1.71.64/2722.1.71.65 to 22.1.71.9422.1.71.9530
6022.1.71.96/2722.1.71.97 to 22.1.71.12622.1.71.12730
6122.1.71.128/2722.1.71.129 to 22.1.71.15822.1.71.15930
6222.1.71.160/2722.1.71.161 to 22.1.71.19022.1.71.19130
6322.1.71.192/2722.1.71.193 to 22.1.71.22222.1.71.22330
6422.1.71.224/2722.1.71.225 to 22.1.71.25422.1.71.25530
6522.1.72.0/2722.1.72.1 to 22.1.72.3022.1.72.3130
6622.1.72.32/2722.1.72.33 to 22.1.72.6222.1.72.6330
6722.1.72.64/2722.1.72.65 to 22.1.72.9422.1.72.9530
6822.1.72.96/2722.1.72.97 to 22.1.72.12622.1.72.12730
6922.1.72.128/2722.1.72.129 to 22.1.72.15822.1.72.15930
7022.1.72.160/2722.1.72.161 to 22.1.72.19022.1.72.19130
7122.1.72.192/2722.1.72.193 to 22.1.72.22222.1.72.22330
7222.1.72.224/2722.1.72.225 to 22.1.72.25422.1.72.25530
7322.1.73.0/2722.1.73.1 to 22.1.73.3022.1.73.3130
7422.1.73.32/2722.1.73.33 to 22.1.73.6222.1.73.6330
7522.1.73.64/2722.1.73.65 to 22.1.73.9422.1.73.9530
7622.1.73.96/2722.1.73.97 to 22.1.73.12622.1.73.12730
7722.1.73.128/2722.1.73.129 to 22.1.73.15822.1.73.15930
7822.1.73.160/2722.1.73.161 to 22.1.73.19022.1.73.19130
7922.1.73.192/2722.1.73.193 to 22.1.73.22222.1.73.22330
8022.1.73.224/2722.1.73.225 to 22.1.73.25422.1.73.25530
8122.1.74.0/2722.1.74.1 to 22.1.74.3022.1.74.3130
8222.1.74.32/2722.1.74.33 to 22.1.74.6222.1.74.6330
8322.1.74.64/2722.1.74.65 to 22.1.74.9422.1.74.9530
8422.1.74.96/2722.1.74.97 to 22.1.74.12622.1.74.12730
8522.1.74.128/2722.1.74.129 to 22.1.74.15822.1.74.15930
8622.1.74.160/2722.1.74.161 to 22.1.74.19022.1.74.19130
8722.1.74.192/2722.1.74.193 to 22.1.74.22222.1.74.22330
8822.1.74.224/2722.1.74.225 to 22.1.74.25422.1.74.25530
8922.1.75.0/2722.1.75.1 to 22.1.75.3022.1.75.3130
9022.1.75.32/2722.1.75.33 to 22.1.75.6222.1.75.6330
9122.1.75.64/2722.1.75.65 to 22.1.75.9422.1.75.9530
9222.1.75.96/2722.1.75.97 to 22.1.75.12622.1.75.12730
9322.1.75.128/2722.1.75.129 to 22.1.75.15822.1.75.15930
9422.1.75.160/2722.1.75.161 to 22.1.75.19022.1.75.19130
9522.1.75.192/2722.1.75.193 to 22.1.75.22222.1.75.22330
9622.1.75.224/2722.1.75.225 to 22.1.75.25422.1.75.25530
9722.1.76.0/2722.1.76.1 to 22.1.76.3022.1.76.3130
9822.1.76.32/2722.1.76.33 to 22.1.76.6222.1.76.6330
9922.1.76.64/2722.1.76.65 to 22.1.76.9422.1.76.9530
10022.1.76.96/2722.1.76.97 to 22.1.76.12622.1.76.12730
10122.1.76.128/2722.1.76.129 to 22.1.76.15822.1.76.15930
10222.1.76.160/2722.1.76.161 to 22.1.76.19022.1.76.19130
10322.1.76.192/2722.1.76.193 to 22.1.76.22222.1.76.22330
10422.1.76.224/2722.1.76.225 to 22.1.76.25422.1.76.25530
10522.1.77.0/2722.1.77.1 to 22.1.77.3022.1.77.3130
10622.1.77.32/2722.1.77.33 to 22.1.77.6222.1.77.6330
10722.1.77.64/2722.1.77.65 to 22.1.77.9422.1.77.9530
10822.1.77.96/2722.1.77.97 to 22.1.77.12622.1.77.12730
10922.1.77.128/2722.1.77.129 to 22.1.77.15822.1.77.15930
11022.1.77.160/2722.1.77.161 to 22.1.77.19022.1.77.19130
11122.1.77.192/2722.1.77.193 to 22.1.77.22222.1.77.22330
11222.1.77.224/2722.1.77.225 to 22.1.77.25422.1.77.25530
11322.1.78.0/2722.1.78.1 to 22.1.78.3022.1.78.3130
11422.1.78.32/2722.1.78.33 to 22.1.78.6222.1.78.6330
11522.1.78.64/2722.1.78.65 to 22.1.78.9422.1.78.9530
11622.1.78.96/2722.1.78.97 to 22.1.78.12622.1.78.12730
11722.1.78.128/2722.1.78.129 to 22.1.78.15822.1.78.15930
11822.1.78.160/2722.1.78.161 to 22.1.78.19022.1.78.19130
11922.1.78.192/2722.1.78.193 to 22.1.78.22222.1.78.22330
12022.1.78.224/2722.1.78.225 to 22.1.78.25422.1.78.25530
12122.1.79.0/2722.1.79.1 to 22.1.79.3022.1.79.3130
12222.1.79.32/2722.1.79.33 to 22.1.79.6222.1.79.6330
12322.1.79.64/2722.1.79.65 to 22.1.79.9422.1.79.9530
12422.1.79.96/2722.1.79.97 to 22.1.79.12622.1.79.12730
12522.1.79.128/2722.1.79.129 to 22.1.79.15822.1.79.15930
12622.1.79.160/2722.1.79.161 to 22.1.79.19022.1.79.19130
12722.1.79.192/2722.1.79.193 to 22.1.79.22222.1.79.22330
12822.1.79.224/2722.1.79.225 to 22.1.79.25422.1.79.25530

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.