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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.

Network22.2.0.0/17
Usable hosts32,766
Subnet mask255.255.128.0
Addresses32,768
Network address
22.2.0.0
Broadcast address
22.2.127.255
First usable
22.2.0.1
Last usable
22.2.127.254
Usable hosts
32,766 (32,768 less the network and broadcast addresses)
Subnet mask
255.255.128.0
Wildcard mask
0.0.127.255 (Cisco ACLs, OSPF)
Prefix length
/17
Type
Public public
Old class
A (default /8)
As numbers
Hex 16020000 · Integer 369229824 to 369262591
Reverse DNS zones
0.2.22.in-addr.arpa
1.2.22.in-addr.arpa
2.2.22.in-addr.arpa
3.2.22.in-addr.arpa
4.2.22.in-addr.arpa
5.2.22.in-addr.arpa
6.2.22.in-addr.arpa
7.2.22.in-addr.arpa
8.2.22.in-addr.arpa
9.2.22.in-addr.arpa
10.2.22.in-addr.arpa
11.2.22.in-addr.arpa
12.2.22.in-addr.arpa
13.2.22.in-addr.arpa
14.2.22.in-addr.arpa
15.2.22.in-addr.arpa
and 112 more
/17 is not on a 8-bit boundary, so it takes 128 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00010110.00000010.00000000.0000000022.2.0.0
Subnet mask11111111.11111111.10000000.00000000255.255.128.0
Network00010110.00000010.00000000.0000000022.2.0.0
Broadcast00010110.00000010.01111111.1111111122.2.127.255
Split into smaller subnets/24
/18 (2)/19 (4)/20 (8)/21 (16)/22 (32)/23 (64)/24 (128)/25 (256)/26 (512)/27 (1,024)/28 (2,048)/29 (4,096)

22.2.0.0/17 makes 128 subnets of /24.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
122.2.0.0/2422.2.0.1 to 22.2.0.25422.2.0.255254
222.2.1.0/2422.2.1.1 to 22.2.1.25422.2.1.255254
322.2.2.0/2422.2.2.1 to 22.2.2.25422.2.2.255254
422.2.3.0/2422.2.3.1 to 22.2.3.25422.2.3.255254
522.2.4.0/2422.2.4.1 to 22.2.4.25422.2.4.255254
622.2.5.0/2422.2.5.1 to 22.2.5.25422.2.5.255254
722.2.6.0/2422.2.6.1 to 22.2.6.25422.2.6.255254
822.2.7.0/2422.2.7.1 to 22.2.7.25422.2.7.255254
922.2.8.0/2422.2.8.1 to 22.2.8.25422.2.8.255254
1022.2.9.0/2422.2.9.1 to 22.2.9.25422.2.9.255254
1122.2.10.0/2422.2.10.1 to 22.2.10.25422.2.10.255254
1222.2.11.0/2422.2.11.1 to 22.2.11.25422.2.11.255254
1322.2.12.0/2422.2.12.1 to 22.2.12.25422.2.12.255254
1422.2.13.0/2422.2.13.1 to 22.2.13.25422.2.13.255254
1522.2.14.0/2422.2.14.1 to 22.2.14.25422.2.14.255254
1622.2.15.0/2422.2.15.1 to 22.2.15.25422.2.15.255254
1722.2.16.0/2422.2.16.1 to 22.2.16.25422.2.16.255254
1822.2.17.0/2422.2.17.1 to 22.2.17.25422.2.17.255254
1922.2.18.0/2422.2.18.1 to 22.2.18.25422.2.18.255254
2022.2.19.0/2422.2.19.1 to 22.2.19.25422.2.19.255254
2122.2.20.0/2422.2.20.1 to 22.2.20.25422.2.20.255254
2222.2.21.0/2422.2.21.1 to 22.2.21.25422.2.21.255254
2322.2.22.0/2422.2.22.1 to 22.2.22.25422.2.22.255254
2422.2.23.0/2422.2.23.1 to 22.2.23.25422.2.23.255254
2522.2.24.0/2422.2.24.1 to 22.2.24.25422.2.24.255254
2622.2.25.0/2422.2.25.1 to 22.2.25.25422.2.25.255254
2722.2.26.0/2422.2.26.1 to 22.2.26.25422.2.26.255254
2822.2.27.0/2422.2.27.1 to 22.2.27.25422.2.27.255254
2922.2.28.0/2422.2.28.1 to 22.2.28.25422.2.28.255254
3022.2.29.0/2422.2.29.1 to 22.2.29.25422.2.29.255254
3122.2.30.0/2422.2.30.1 to 22.2.30.25422.2.30.255254
3222.2.31.0/2422.2.31.1 to 22.2.31.25422.2.31.255254
3322.2.32.0/2422.2.32.1 to 22.2.32.25422.2.32.255254
3422.2.33.0/2422.2.33.1 to 22.2.33.25422.2.33.255254
3522.2.34.0/2422.2.34.1 to 22.2.34.25422.2.34.255254
3622.2.35.0/2422.2.35.1 to 22.2.35.25422.2.35.255254
3722.2.36.0/2422.2.36.1 to 22.2.36.25422.2.36.255254
3822.2.37.0/2422.2.37.1 to 22.2.37.25422.2.37.255254
3922.2.38.0/2422.2.38.1 to 22.2.38.25422.2.38.255254
4022.2.39.0/2422.2.39.1 to 22.2.39.25422.2.39.255254
4122.2.40.0/2422.2.40.1 to 22.2.40.25422.2.40.255254
4222.2.41.0/2422.2.41.1 to 22.2.41.25422.2.41.255254
4322.2.42.0/2422.2.42.1 to 22.2.42.25422.2.42.255254
4422.2.43.0/2422.2.43.1 to 22.2.43.25422.2.43.255254
4522.2.44.0/2422.2.44.1 to 22.2.44.25422.2.44.255254
4622.2.45.0/2422.2.45.1 to 22.2.45.25422.2.45.255254
4722.2.46.0/2422.2.46.1 to 22.2.46.25422.2.46.255254
4822.2.47.0/2422.2.47.1 to 22.2.47.25422.2.47.255254
4922.2.48.0/2422.2.48.1 to 22.2.48.25422.2.48.255254
5022.2.49.0/2422.2.49.1 to 22.2.49.25422.2.49.255254
5122.2.50.0/2422.2.50.1 to 22.2.50.25422.2.50.255254
5222.2.51.0/2422.2.51.1 to 22.2.51.25422.2.51.255254
5322.2.52.0/2422.2.52.1 to 22.2.52.25422.2.52.255254
5422.2.53.0/2422.2.53.1 to 22.2.53.25422.2.53.255254
5522.2.54.0/2422.2.54.1 to 22.2.54.25422.2.54.255254
5622.2.55.0/2422.2.55.1 to 22.2.55.25422.2.55.255254
5722.2.56.0/2422.2.56.1 to 22.2.56.25422.2.56.255254
5822.2.57.0/2422.2.57.1 to 22.2.57.25422.2.57.255254
5922.2.58.0/2422.2.58.1 to 22.2.58.25422.2.58.255254
6022.2.59.0/2422.2.59.1 to 22.2.59.25422.2.59.255254
6122.2.60.0/2422.2.60.1 to 22.2.60.25422.2.60.255254
6222.2.61.0/2422.2.61.1 to 22.2.61.25422.2.61.255254
6322.2.62.0/2422.2.62.1 to 22.2.62.25422.2.62.255254
6422.2.63.0/2422.2.63.1 to 22.2.63.25422.2.63.255254
6522.2.64.0/2422.2.64.1 to 22.2.64.25422.2.64.255254
6622.2.65.0/2422.2.65.1 to 22.2.65.25422.2.65.255254
6722.2.66.0/2422.2.66.1 to 22.2.66.25422.2.66.255254
6822.2.67.0/2422.2.67.1 to 22.2.67.25422.2.67.255254
6922.2.68.0/2422.2.68.1 to 22.2.68.25422.2.68.255254
7022.2.69.0/2422.2.69.1 to 22.2.69.25422.2.69.255254
7122.2.70.0/2422.2.70.1 to 22.2.70.25422.2.70.255254
7222.2.71.0/2422.2.71.1 to 22.2.71.25422.2.71.255254
7322.2.72.0/2422.2.72.1 to 22.2.72.25422.2.72.255254
7422.2.73.0/2422.2.73.1 to 22.2.73.25422.2.73.255254
7522.2.74.0/2422.2.74.1 to 22.2.74.25422.2.74.255254
7622.2.75.0/2422.2.75.1 to 22.2.75.25422.2.75.255254
7722.2.76.0/2422.2.76.1 to 22.2.76.25422.2.76.255254
7822.2.77.0/2422.2.77.1 to 22.2.77.25422.2.77.255254
7922.2.78.0/2422.2.78.1 to 22.2.78.25422.2.78.255254
8022.2.79.0/2422.2.79.1 to 22.2.79.25422.2.79.255254
8122.2.80.0/2422.2.80.1 to 22.2.80.25422.2.80.255254
8222.2.81.0/2422.2.81.1 to 22.2.81.25422.2.81.255254
8322.2.82.0/2422.2.82.1 to 22.2.82.25422.2.82.255254
8422.2.83.0/2422.2.83.1 to 22.2.83.25422.2.83.255254
8522.2.84.0/2422.2.84.1 to 22.2.84.25422.2.84.255254
8622.2.85.0/2422.2.85.1 to 22.2.85.25422.2.85.255254
8722.2.86.0/2422.2.86.1 to 22.2.86.25422.2.86.255254
8822.2.87.0/2422.2.87.1 to 22.2.87.25422.2.87.255254
8922.2.88.0/2422.2.88.1 to 22.2.88.25422.2.88.255254
9022.2.89.0/2422.2.89.1 to 22.2.89.25422.2.89.255254
9122.2.90.0/2422.2.90.1 to 22.2.90.25422.2.90.255254
9222.2.91.0/2422.2.91.1 to 22.2.91.25422.2.91.255254
9322.2.92.0/2422.2.92.1 to 22.2.92.25422.2.92.255254
9422.2.93.0/2422.2.93.1 to 22.2.93.25422.2.93.255254
9522.2.94.0/2422.2.94.1 to 22.2.94.25422.2.94.255254
9622.2.95.0/2422.2.95.1 to 22.2.95.25422.2.95.255254
9722.2.96.0/2422.2.96.1 to 22.2.96.25422.2.96.255254
9822.2.97.0/2422.2.97.1 to 22.2.97.25422.2.97.255254
9922.2.98.0/2422.2.98.1 to 22.2.98.25422.2.98.255254
10022.2.99.0/2422.2.99.1 to 22.2.99.25422.2.99.255254
10122.2.100.0/2422.2.100.1 to 22.2.100.25422.2.100.255254
10222.2.101.0/2422.2.101.1 to 22.2.101.25422.2.101.255254
10322.2.102.0/2422.2.102.1 to 22.2.102.25422.2.102.255254
10422.2.103.0/2422.2.103.1 to 22.2.103.25422.2.103.255254
10522.2.104.0/2422.2.104.1 to 22.2.104.25422.2.104.255254
10622.2.105.0/2422.2.105.1 to 22.2.105.25422.2.105.255254
10722.2.106.0/2422.2.106.1 to 22.2.106.25422.2.106.255254
10822.2.107.0/2422.2.107.1 to 22.2.107.25422.2.107.255254
10922.2.108.0/2422.2.108.1 to 22.2.108.25422.2.108.255254
11022.2.109.0/2422.2.109.1 to 22.2.109.25422.2.109.255254
11122.2.110.0/2422.2.110.1 to 22.2.110.25422.2.110.255254
11222.2.111.0/2422.2.111.1 to 22.2.111.25422.2.111.255254
11322.2.112.0/2422.2.112.1 to 22.2.112.25422.2.112.255254
11422.2.113.0/2422.2.113.1 to 22.2.113.25422.2.113.255254
11522.2.114.0/2422.2.114.1 to 22.2.114.25422.2.114.255254
11622.2.115.0/2422.2.115.1 to 22.2.115.25422.2.115.255254
11722.2.116.0/2422.2.116.1 to 22.2.116.25422.2.116.255254
11822.2.117.0/2422.2.117.1 to 22.2.117.25422.2.117.255254
11922.2.118.0/2422.2.118.1 to 22.2.118.25422.2.118.255254
12022.2.119.0/2422.2.119.1 to 22.2.119.25422.2.119.255254
12122.2.120.0/2422.2.120.1 to 22.2.120.25422.2.120.255254
12222.2.121.0/2422.2.121.1 to 22.2.121.25422.2.121.255254
12322.2.122.0/2422.2.122.1 to 22.2.122.25422.2.122.255254
12422.2.123.0/2422.2.123.1 to 22.2.123.25422.2.123.255254
12522.2.124.0/2422.2.124.1 to 22.2.124.25422.2.124.255254
12622.2.125.0/2422.2.125.1 to 22.2.125.25422.2.125.255254
12722.2.126.0/2422.2.126.1 to 22.2.126.25422.2.126.255254
12822.2.127.0/2422.2.127.1 to 22.2.127.25422.2.127.255254

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.