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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.

Network77.2.64.0/18
Usable hosts16,382
Subnet mask255.255.192.0
Addresses16,384
Network address
77.2.64.0
Broadcast address
77.2.127.255
First usable
77.2.64.1
Last usable
77.2.127.254
Usable hosts
16,382 (16,384 less the network and broadcast addresses)
Subnet mask
255.255.192.0
Wildcard mask
0.0.63.255 (Cisco ACLs, OSPF)
Prefix length
/18
Type
Public public
Old class
A (default /8)
As numbers
Hex 4D024000 · Integer 1291993088 to 1292009471
Reverse DNS zones
64.2.77.in-addr.arpa
65.2.77.in-addr.arpa
66.2.77.in-addr.arpa
67.2.77.in-addr.arpa
68.2.77.in-addr.arpa
69.2.77.in-addr.arpa
70.2.77.in-addr.arpa
71.2.77.in-addr.arpa
72.2.77.in-addr.arpa
73.2.77.in-addr.arpa
74.2.77.in-addr.arpa
75.2.77.in-addr.arpa
76.2.77.in-addr.arpa
77.2.77.in-addr.arpa
78.2.77.in-addr.arpa
79.2.77.in-addr.arpa
and 48 more
/18 is not on a 8-bit boundary, so it takes 64 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01001101.00000010.01000000.0000000077.2.64.0
Subnet mask11111111.11111111.11000000.00000000255.255.192.0
Network01001101.00000010.01000000.0000000077.2.64.0
Broadcast01001101.00000010.01111111.1111111177.2.127.255
Split into smaller subnets/25
/19 (2)/20 (4)/21 (8)/22 (16)/23 (32)/24 (64)/25 (128)/26 (256)/27 (512)/28 (1,024)/29 (2,048)/30 (4,096)

77.2.64.0/18 makes 128 subnets of /25.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
177.2.64.0/2577.2.64.1 to 77.2.64.12677.2.64.127126
277.2.64.128/2577.2.64.129 to 77.2.64.25477.2.64.255126
377.2.65.0/2577.2.65.1 to 77.2.65.12677.2.65.127126
477.2.65.128/2577.2.65.129 to 77.2.65.25477.2.65.255126
577.2.66.0/2577.2.66.1 to 77.2.66.12677.2.66.127126
677.2.66.128/2577.2.66.129 to 77.2.66.25477.2.66.255126
777.2.67.0/2577.2.67.1 to 77.2.67.12677.2.67.127126
877.2.67.128/2577.2.67.129 to 77.2.67.25477.2.67.255126
977.2.68.0/2577.2.68.1 to 77.2.68.12677.2.68.127126
1077.2.68.128/2577.2.68.129 to 77.2.68.25477.2.68.255126
1177.2.69.0/2577.2.69.1 to 77.2.69.12677.2.69.127126
1277.2.69.128/2577.2.69.129 to 77.2.69.25477.2.69.255126
1377.2.70.0/2577.2.70.1 to 77.2.70.12677.2.70.127126
1477.2.70.128/2577.2.70.129 to 77.2.70.25477.2.70.255126
1577.2.71.0/2577.2.71.1 to 77.2.71.12677.2.71.127126
1677.2.71.128/2577.2.71.129 to 77.2.71.25477.2.71.255126
1777.2.72.0/2577.2.72.1 to 77.2.72.12677.2.72.127126
1877.2.72.128/2577.2.72.129 to 77.2.72.25477.2.72.255126
1977.2.73.0/2577.2.73.1 to 77.2.73.12677.2.73.127126
2077.2.73.128/2577.2.73.129 to 77.2.73.25477.2.73.255126
2177.2.74.0/2577.2.74.1 to 77.2.74.12677.2.74.127126
2277.2.74.128/2577.2.74.129 to 77.2.74.25477.2.74.255126
2377.2.75.0/2577.2.75.1 to 77.2.75.12677.2.75.127126
2477.2.75.128/2577.2.75.129 to 77.2.75.25477.2.75.255126
2577.2.76.0/2577.2.76.1 to 77.2.76.12677.2.76.127126
2677.2.76.128/2577.2.76.129 to 77.2.76.25477.2.76.255126
2777.2.77.0/2577.2.77.1 to 77.2.77.12677.2.77.127126
2877.2.77.128/2577.2.77.129 to 77.2.77.25477.2.77.255126
2977.2.78.0/2577.2.78.1 to 77.2.78.12677.2.78.127126
3077.2.78.128/2577.2.78.129 to 77.2.78.25477.2.78.255126
3177.2.79.0/2577.2.79.1 to 77.2.79.12677.2.79.127126
3277.2.79.128/2577.2.79.129 to 77.2.79.25477.2.79.255126
3377.2.80.0/2577.2.80.1 to 77.2.80.12677.2.80.127126
3477.2.80.128/2577.2.80.129 to 77.2.80.25477.2.80.255126
3577.2.81.0/2577.2.81.1 to 77.2.81.12677.2.81.127126
3677.2.81.128/2577.2.81.129 to 77.2.81.25477.2.81.255126
3777.2.82.0/2577.2.82.1 to 77.2.82.12677.2.82.127126
3877.2.82.128/2577.2.82.129 to 77.2.82.25477.2.82.255126
3977.2.83.0/2577.2.83.1 to 77.2.83.12677.2.83.127126
4077.2.83.128/2577.2.83.129 to 77.2.83.25477.2.83.255126
4177.2.84.0/2577.2.84.1 to 77.2.84.12677.2.84.127126
4277.2.84.128/2577.2.84.129 to 77.2.84.25477.2.84.255126
4377.2.85.0/2577.2.85.1 to 77.2.85.12677.2.85.127126
4477.2.85.128/2577.2.85.129 to 77.2.85.25477.2.85.255126
4577.2.86.0/2577.2.86.1 to 77.2.86.12677.2.86.127126
4677.2.86.128/2577.2.86.129 to 77.2.86.25477.2.86.255126
4777.2.87.0/2577.2.87.1 to 77.2.87.12677.2.87.127126
4877.2.87.128/2577.2.87.129 to 77.2.87.25477.2.87.255126
4977.2.88.0/2577.2.88.1 to 77.2.88.12677.2.88.127126
5077.2.88.128/2577.2.88.129 to 77.2.88.25477.2.88.255126
5177.2.89.0/2577.2.89.1 to 77.2.89.12677.2.89.127126
5277.2.89.128/2577.2.89.129 to 77.2.89.25477.2.89.255126
5377.2.90.0/2577.2.90.1 to 77.2.90.12677.2.90.127126
5477.2.90.128/2577.2.90.129 to 77.2.90.25477.2.90.255126
5577.2.91.0/2577.2.91.1 to 77.2.91.12677.2.91.127126
5677.2.91.128/2577.2.91.129 to 77.2.91.25477.2.91.255126
5777.2.92.0/2577.2.92.1 to 77.2.92.12677.2.92.127126
5877.2.92.128/2577.2.92.129 to 77.2.92.25477.2.92.255126
5977.2.93.0/2577.2.93.1 to 77.2.93.12677.2.93.127126
6077.2.93.128/2577.2.93.129 to 77.2.93.25477.2.93.255126
6177.2.94.0/2577.2.94.1 to 77.2.94.12677.2.94.127126
6277.2.94.128/2577.2.94.129 to 77.2.94.25477.2.94.255126
6377.2.95.0/2577.2.95.1 to 77.2.95.12677.2.95.127126
6477.2.95.128/2577.2.95.129 to 77.2.95.25477.2.95.255126
6577.2.96.0/2577.2.96.1 to 77.2.96.12677.2.96.127126
6677.2.96.128/2577.2.96.129 to 77.2.96.25477.2.96.255126
6777.2.97.0/2577.2.97.1 to 77.2.97.12677.2.97.127126
6877.2.97.128/2577.2.97.129 to 77.2.97.25477.2.97.255126
6977.2.98.0/2577.2.98.1 to 77.2.98.12677.2.98.127126
7077.2.98.128/2577.2.98.129 to 77.2.98.25477.2.98.255126
7177.2.99.0/2577.2.99.1 to 77.2.99.12677.2.99.127126
7277.2.99.128/2577.2.99.129 to 77.2.99.25477.2.99.255126
7377.2.100.0/2577.2.100.1 to 77.2.100.12677.2.100.127126
7477.2.100.128/2577.2.100.129 to 77.2.100.25477.2.100.255126
7577.2.101.0/2577.2.101.1 to 77.2.101.12677.2.101.127126
7677.2.101.128/2577.2.101.129 to 77.2.101.25477.2.101.255126
7777.2.102.0/2577.2.102.1 to 77.2.102.12677.2.102.127126
7877.2.102.128/2577.2.102.129 to 77.2.102.25477.2.102.255126
7977.2.103.0/2577.2.103.1 to 77.2.103.12677.2.103.127126
8077.2.103.128/2577.2.103.129 to 77.2.103.25477.2.103.255126
8177.2.104.0/2577.2.104.1 to 77.2.104.12677.2.104.127126
8277.2.104.128/2577.2.104.129 to 77.2.104.25477.2.104.255126
8377.2.105.0/2577.2.105.1 to 77.2.105.12677.2.105.127126
8477.2.105.128/2577.2.105.129 to 77.2.105.25477.2.105.255126
8577.2.106.0/2577.2.106.1 to 77.2.106.12677.2.106.127126
8677.2.106.128/2577.2.106.129 to 77.2.106.25477.2.106.255126
8777.2.107.0/2577.2.107.1 to 77.2.107.12677.2.107.127126
8877.2.107.128/2577.2.107.129 to 77.2.107.25477.2.107.255126
8977.2.108.0/2577.2.108.1 to 77.2.108.12677.2.108.127126
9077.2.108.128/2577.2.108.129 to 77.2.108.25477.2.108.255126
9177.2.109.0/2577.2.109.1 to 77.2.109.12677.2.109.127126
9277.2.109.128/2577.2.109.129 to 77.2.109.25477.2.109.255126
9377.2.110.0/2577.2.110.1 to 77.2.110.12677.2.110.127126
9477.2.110.128/2577.2.110.129 to 77.2.110.25477.2.110.255126
9577.2.111.0/2577.2.111.1 to 77.2.111.12677.2.111.127126
9677.2.111.128/2577.2.111.129 to 77.2.111.25477.2.111.255126
9777.2.112.0/2577.2.112.1 to 77.2.112.12677.2.112.127126
9877.2.112.128/2577.2.112.129 to 77.2.112.25477.2.112.255126
9977.2.113.0/2577.2.113.1 to 77.2.113.12677.2.113.127126
10077.2.113.128/2577.2.113.129 to 77.2.113.25477.2.113.255126
10177.2.114.0/2577.2.114.1 to 77.2.114.12677.2.114.127126
10277.2.114.128/2577.2.114.129 to 77.2.114.25477.2.114.255126
10377.2.115.0/2577.2.115.1 to 77.2.115.12677.2.115.127126
10477.2.115.128/2577.2.115.129 to 77.2.115.25477.2.115.255126
10577.2.116.0/2577.2.116.1 to 77.2.116.12677.2.116.127126
10677.2.116.128/2577.2.116.129 to 77.2.116.25477.2.116.255126
10777.2.117.0/2577.2.117.1 to 77.2.117.12677.2.117.127126
10877.2.117.128/2577.2.117.129 to 77.2.117.25477.2.117.255126
10977.2.118.0/2577.2.118.1 to 77.2.118.12677.2.118.127126
11077.2.118.128/2577.2.118.129 to 77.2.118.25477.2.118.255126
11177.2.119.0/2577.2.119.1 to 77.2.119.12677.2.119.127126
11277.2.119.128/2577.2.119.129 to 77.2.119.25477.2.119.255126
11377.2.120.0/2577.2.120.1 to 77.2.120.12677.2.120.127126
11477.2.120.128/2577.2.120.129 to 77.2.120.25477.2.120.255126
11577.2.121.0/2577.2.121.1 to 77.2.121.12677.2.121.127126
11677.2.121.128/2577.2.121.129 to 77.2.121.25477.2.121.255126
11777.2.122.0/2577.2.122.1 to 77.2.122.12677.2.122.127126
11877.2.122.128/2577.2.122.129 to 77.2.122.25477.2.122.255126
11977.2.123.0/2577.2.123.1 to 77.2.123.12677.2.123.127126
12077.2.123.128/2577.2.123.129 to 77.2.123.25477.2.123.255126
12177.2.124.0/2577.2.124.1 to 77.2.124.12677.2.124.127126
12277.2.124.128/2577.2.124.129 to 77.2.124.25477.2.124.255126
12377.2.125.0/2577.2.125.1 to 77.2.125.12677.2.125.127126
12477.2.125.128/2577.2.125.129 to 77.2.125.25477.2.125.255126
12577.2.126.0/2577.2.126.1 to 77.2.126.12677.2.126.127126
12677.2.126.128/2577.2.126.129 to 77.2.126.25477.2.126.255126
12777.2.127.0/2577.2.127.1 to 77.2.127.12677.2.127.127126
12877.2.127.128/2577.2.127.129 to 77.2.127.25477.2.127.255126

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.