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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.

Network67.0.0.0/9
Usable hosts8,388,606
Subnet mask255.128.0.0
Addresses8,388,608
Network address
67.0.0.0
Broadcast address
67.127.255.255
First usable
67.0.0.1
Last usable
67.127.255.254
Usable hosts
8,388,606 (8,388,608 less the network and broadcast addresses)
Subnet mask
255.128.0.0
Wildcard mask
0.127.255.255 (Cisco ACLs, OSPF)
Prefix length
/9
Type
Public public
Old class
A (default /8)
As numbers
Hex 43000000 · Integer 1124073472 to 1132462079
Reverse DNS zones
0.67.in-addr.arpa
1.67.in-addr.arpa
2.67.in-addr.arpa
3.67.in-addr.arpa
4.67.in-addr.arpa
5.67.in-addr.arpa
6.67.in-addr.arpa
7.67.in-addr.arpa
8.67.in-addr.arpa
9.67.in-addr.arpa
10.67.in-addr.arpa
11.67.in-addr.arpa
12.67.in-addr.arpa
13.67.in-addr.arpa
14.67.in-addr.arpa
15.67.in-addr.arpa
and 112 more
/9 is not on a 8-bit boundary, so it takes 128 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01000011.00000000.00000000.0000000067.0.0.0
Subnet mask11111111.10000000.00000000.00000000255.128.0.0
Network01000011.00000000.00000000.0000000067.0.0.0
Broadcast01000011.01111111.11111111.1111111167.127.255.255
Split into smaller subnets/16
/10 (2)/11 (4)/12 (8)/13 (16)/14 (32)/15 (64)/16 (128)/17 (256)/18 (512)/19 (1,024)/20 (2,048)/21 (4,096)

67.0.0.0/9 makes 128 subnets of /16.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
167.0.0.0/1667.0.0.1 to 67.0.255.25467.0.255.25565,534
267.1.0.0/1667.1.0.1 to 67.1.255.25467.1.255.25565,534
367.2.0.0/1667.2.0.1 to 67.2.255.25467.2.255.25565,534
467.3.0.0/1667.3.0.1 to 67.3.255.25467.3.255.25565,534
567.4.0.0/1667.4.0.1 to 67.4.255.25467.4.255.25565,534
667.5.0.0/1667.5.0.1 to 67.5.255.25467.5.255.25565,534
767.6.0.0/1667.6.0.1 to 67.6.255.25467.6.255.25565,534
867.7.0.0/1667.7.0.1 to 67.7.255.25467.7.255.25565,534
967.8.0.0/1667.8.0.1 to 67.8.255.25467.8.255.25565,534
1067.9.0.0/1667.9.0.1 to 67.9.255.25467.9.255.25565,534
1167.10.0.0/1667.10.0.1 to 67.10.255.25467.10.255.25565,534
1267.11.0.0/1667.11.0.1 to 67.11.255.25467.11.255.25565,534
1367.12.0.0/1667.12.0.1 to 67.12.255.25467.12.255.25565,534
1467.13.0.0/1667.13.0.1 to 67.13.255.25467.13.255.25565,534
1567.14.0.0/1667.14.0.1 to 67.14.255.25467.14.255.25565,534
1667.15.0.0/1667.15.0.1 to 67.15.255.25467.15.255.25565,534
1767.16.0.0/1667.16.0.1 to 67.16.255.25467.16.255.25565,534
1867.17.0.0/1667.17.0.1 to 67.17.255.25467.17.255.25565,534
1967.18.0.0/1667.18.0.1 to 67.18.255.25467.18.255.25565,534
2067.19.0.0/1667.19.0.1 to 67.19.255.25467.19.255.25565,534
2167.20.0.0/1667.20.0.1 to 67.20.255.25467.20.255.25565,534
2267.21.0.0/1667.21.0.1 to 67.21.255.25467.21.255.25565,534
2367.22.0.0/1667.22.0.1 to 67.22.255.25467.22.255.25565,534
2467.23.0.0/1667.23.0.1 to 67.23.255.25467.23.255.25565,534
2567.24.0.0/1667.24.0.1 to 67.24.255.25467.24.255.25565,534
2667.25.0.0/1667.25.0.1 to 67.25.255.25467.25.255.25565,534
2767.26.0.0/1667.26.0.1 to 67.26.255.25467.26.255.25565,534
2867.27.0.0/1667.27.0.1 to 67.27.255.25467.27.255.25565,534
2967.28.0.0/1667.28.0.1 to 67.28.255.25467.28.255.25565,534
3067.29.0.0/1667.29.0.1 to 67.29.255.25467.29.255.25565,534
3167.30.0.0/1667.30.0.1 to 67.30.255.25467.30.255.25565,534
3267.31.0.0/1667.31.0.1 to 67.31.255.25467.31.255.25565,534
3367.32.0.0/1667.32.0.1 to 67.32.255.25467.32.255.25565,534
3467.33.0.0/1667.33.0.1 to 67.33.255.25467.33.255.25565,534
3567.34.0.0/1667.34.0.1 to 67.34.255.25467.34.255.25565,534
3667.35.0.0/1667.35.0.1 to 67.35.255.25467.35.255.25565,534
3767.36.0.0/1667.36.0.1 to 67.36.255.25467.36.255.25565,534
3867.37.0.0/1667.37.0.1 to 67.37.255.25467.37.255.25565,534
3967.38.0.0/1667.38.0.1 to 67.38.255.25467.38.255.25565,534
4067.39.0.0/1667.39.0.1 to 67.39.255.25467.39.255.25565,534
4167.40.0.0/1667.40.0.1 to 67.40.255.25467.40.255.25565,534
4267.41.0.0/1667.41.0.1 to 67.41.255.25467.41.255.25565,534
4367.42.0.0/1667.42.0.1 to 67.42.255.25467.42.255.25565,534
4467.43.0.0/1667.43.0.1 to 67.43.255.25467.43.255.25565,534
4567.44.0.0/1667.44.0.1 to 67.44.255.25467.44.255.25565,534
4667.45.0.0/1667.45.0.1 to 67.45.255.25467.45.255.25565,534
4767.46.0.0/1667.46.0.1 to 67.46.255.25467.46.255.25565,534
4867.47.0.0/1667.47.0.1 to 67.47.255.25467.47.255.25565,534
4967.48.0.0/1667.48.0.1 to 67.48.255.25467.48.255.25565,534
5067.49.0.0/1667.49.0.1 to 67.49.255.25467.49.255.25565,534
5167.50.0.0/1667.50.0.1 to 67.50.255.25467.50.255.25565,534
5267.51.0.0/1667.51.0.1 to 67.51.255.25467.51.255.25565,534
5367.52.0.0/1667.52.0.1 to 67.52.255.25467.52.255.25565,534
5467.53.0.0/1667.53.0.1 to 67.53.255.25467.53.255.25565,534
5567.54.0.0/1667.54.0.1 to 67.54.255.25467.54.255.25565,534
5667.55.0.0/1667.55.0.1 to 67.55.255.25467.55.255.25565,534
5767.56.0.0/1667.56.0.1 to 67.56.255.25467.56.255.25565,534
5867.57.0.0/1667.57.0.1 to 67.57.255.25467.57.255.25565,534
5967.58.0.0/1667.58.0.1 to 67.58.255.25467.58.255.25565,534
6067.59.0.0/1667.59.0.1 to 67.59.255.25467.59.255.25565,534
6167.60.0.0/1667.60.0.1 to 67.60.255.25467.60.255.25565,534
6267.61.0.0/1667.61.0.1 to 67.61.255.25467.61.255.25565,534
6367.62.0.0/1667.62.0.1 to 67.62.255.25467.62.255.25565,534
6467.63.0.0/1667.63.0.1 to 67.63.255.25467.63.255.25565,534
6567.64.0.0/1667.64.0.1 to 67.64.255.25467.64.255.25565,534
6667.65.0.0/1667.65.0.1 to 67.65.255.25467.65.255.25565,534
6767.66.0.0/1667.66.0.1 to 67.66.255.25467.66.255.25565,534
6867.67.0.0/1667.67.0.1 to 67.67.255.25467.67.255.25565,534
6967.68.0.0/1667.68.0.1 to 67.68.255.25467.68.255.25565,534
7067.69.0.0/1667.69.0.1 to 67.69.255.25467.69.255.25565,534
7167.70.0.0/1667.70.0.1 to 67.70.255.25467.70.255.25565,534
7267.71.0.0/1667.71.0.1 to 67.71.255.25467.71.255.25565,534
7367.72.0.0/1667.72.0.1 to 67.72.255.25467.72.255.25565,534
7467.73.0.0/1667.73.0.1 to 67.73.255.25467.73.255.25565,534
7567.74.0.0/1667.74.0.1 to 67.74.255.25467.74.255.25565,534
7667.75.0.0/1667.75.0.1 to 67.75.255.25467.75.255.25565,534
7767.76.0.0/1667.76.0.1 to 67.76.255.25467.76.255.25565,534
7867.77.0.0/1667.77.0.1 to 67.77.255.25467.77.255.25565,534
7967.78.0.0/1667.78.0.1 to 67.78.255.25467.78.255.25565,534
8067.79.0.0/1667.79.0.1 to 67.79.255.25467.79.255.25565,534
8167.80.0.0/1667.80.0.1 to 67.80.255.25467.80.255.25565,534
8267.81.0.0/1667.81.0.1 to 67.81.255.25467.81.255.25565,534
8367.82.0.0/1667.82.0.1 to 67.82.255.25467.82.255.25565,534
8467.83.0.0/1667.83.0.1 to 67.83.255.25467.83.255.25565,534
8567.84.0.0/1667.84.0.1 to 67.84.255.25467.84.255.25565,534
8667.85.0.0/1667.85.0.1 to 67.85.255.25467.85.255.25565,534
8767.86.0.0/1667.86.0.1 to 67.86.255.25467.86.255.25565,534
8867.87.0.0/1667.87.0.1 to 67.87.255.25467.87.255.25565,534
8967.88.0.0/1667.88.0.1 to 67.88.255.25467.88.255.25565,534
9067.89.0.0/1667.89.0.1 to 67.89.255.25467.89.255.25565,534
9167.90.0.0/1667.90.0.1 to 67.90.255.25467.90.255.25565,534
9267.91.0.0/1667.91.0.1 to 67.91.255.25467.91.255.25565,534
9367.92.0.0/1667.92.0.1 to 67.92.255.25467.92.255.25565,534
9467.93.0.0/1667.93.0.1 to 67.93.255.25467.93.255.25565,534
9567.94.0.0/1667.94.0.1 to 67.94.255.25467.94.255.25565,534
9667.95.0.0/1667.95.0.1 to 67.95.255.25467.95.255.25565,534
9767.96.0.0/1667.96.0.1 to 67.96.255.25467.96.255.25565,534
9867.97.0.0/1667.97.0.1 to 67.97.255.25467.97.255.25565,534
9967.98.0.0/1667.98.0.1 to 67.98.255.25467.98.255.25565,534
10067.99.0.0/1667.99.0.1 to 67.99.255.25467.99.255.25565,534
10167.100.0.0/1667.100.0.1 to 67.100.255.25467.100.255.25565,534
10267.101.0.0/1667.101.0.1 to 67.101.255.25467.101.255.25565,534
10367.102.0.0/1667.102.0.1 to 67.102.255.25467.102.255.25565,534
10467.103.0.0/1667.103.0.1 to 67.103.255.25467.103.255.25565,534
10567.104.0.0/1667.104.0.1 to 67.104.255.25467.104.255.25565,534
10667.105.0.0/1667.105.0.1 to 67.105.255.25467.105.255.25565,534
10767.106.0.0/1667.106.0.1 to 67.106.255.25467.106.255.25565,534
10867.107.0.0/1667.107.0.1 to 67.107.255.25467.107.255.25565,534
10967.108.0.0/1667.108.0.1 to 67.108.255.25467.108.255.25565,534
11067.109.0.0/1667.109.0.1 to 67.109.255.25467.109.255.25565,534
11167.110.0.0/1667.110.0.1 to 67.110.255.25467.110.255.25565,534
11267.111.0.0/1667.111.0.1 to 67.111.255.25467.111.255.25565,534
11367.112.0.0/1667.112.0.1 to 67.112.255.25467.112.255.25565,534
11467.113.0.0/1667.113.0.1 to 67.113.255.25467.113.255.25565,534
11567.114.0.0/1667.114.0.1 to 67.114.255.25467.114.255.25565,534
11667.115.0.0/1667.115.0.1 to 67.115.255.25467.115.255.25565,534
11767.116.0.0/1667.116.0.1 to 67.116.255.25467.116.255.25565,534
11867.117.0.0/1667.117.0.1 to 67.117.255.25467.117.255.25565,534
11967.118.0.0/1667.118.0.1 to 67.118.255.25467.118.255.25565,534
12067.119.0.0/1667.119.0.1 to 67.119.255.25467.119.255.25565,534
12167.120.0.0/1667.120.0.1 to 67.120.255.25467.120.255.25565,534
12267.121.0.0/1667.121.0.1 to 67.121.255.25467.121.255.25565,534
12367.122.0.0/1667.122.0.1 to 67.122.255.25467.122.255.25565,534
12467.123.0.0/1667.123.0.1 to 67.123.255.25467.123.255.25565,534
12567.124.0.0/1667.124.0.1 to 67.124.255.25467.124.255.25565,534
12667.125.0.0/1667.125.0.1 to 67.125.255.25467.125.255.25565,534
12767.126.0.0/1667.126.0.1 to 67.126.255.25467.126.255.25565,534
12867.127.0.0/1667.127.0.1 to 67.127.255.25467.127.255.25565,534

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.