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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.

Network77.0.0.0/9
Usable hosts8,388,606
Subnet mask255.128.0.0
Addresses8,388,608
Network address
77.0.0.0
Broadcast address
77.127.255.255
First usable
77.0.0.1
Last usable
77.127.255.254
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 4D000000 · Integer 1291845632 to 1300234239
Reverse DNS zones
0.77.in-addr.arpa
1.77.in-addr.arpa
2.77.in-addr.arpa
3.77.in-addr.arpa
4.77.in-addr.arpa
5.77.in-addr.arpa
6.77.in-addr.arpa
7.77.in-addr.arpa
8.77.in-addr.arpa
9.77.in-addr.arpa
10.77.in-addr.arpa
11.77.in-addr.arpa
12.77.in-addr.arpa
13.77.in-addr.arpa
14.77.in-addr.arpa
15.77.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
Address01001101.00000000.00000000.0000000077.0.0.0
Subnet mask11111111.10000000.00000000.00000000255.128.0.0
Network01001101.00000000.00000000.0000000077.0.0.0
Broadcast01001101.01111111.11111111.1111111177.127.255.255
Split into smaller subnets/15
/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)

77.0.0.0/9 makes 64 subnets of /15.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
177.0.0.0/1577.0.0.1 to 77.1.255.25477.1.255.255131,070
277.2.0.0/1577.2.0.1 to 77.3.255.25477.3.255.255131,070
377.4.0.0/1577.4.0.1 to 77.5.255.25477.5.255.255131,070
477.6.0.0/1577.6.0.1 to 77.7.255.25477.7.255.255131,070
577.8.0.0/1577.8.0.1 to 77.9.255.25477.9.255.255131,070
677.10.0.0/1577.10.0.1 to 77.11.255.25477.11.255.255131,070
777.12.0.0/1577.12.0.1 to 77.13.255.25477.13.255.255131,070
877.14.0.0/1577.14.0.1 to 77.15.255.25477.15.255.255131,070
977.16.0.0/1577.16.0.1 to 77.17.255.25477.17.255.255131,070
1077.18.0.0/1577.18.0.1 to 77.19.255.25477.19.255.255131,070
1177.20.0.0/1577.20.0.1 to 77.21.255.25477.21.255.255131,070
1277.22.0.0/1577.22.0.1 to 77.23.255.25477.23.255.255131,070
1377.24.0.0/1577.24.0.1 to 77.25.255.25477.25.255.255131,070
1477.26.0.0/1577.26.0.1 to 77.27.255.25477.27.255.255131,070
1577.28.0.0/1577.28.0.1 to 77.29.255.25477.29.255.255131,070
1677.30.0.0/1577.30.0.1 to 77.31.255.25477.31.255.255131,070
1777.32.0.0/1577.32.0.1 to 77.33.255.25477.33.255.255131,070
1877.34.0.0/1577.34.0.1 to 77.35.255.25477.35.255.255131,070
1977.36.0.0/1577.36.0.1 to 77.37.255.25477.37.255.255131,070
2077.38.0.0/1577.38.0.1 to 77.39.255.25477.39.255.255131,070
2177.40.0.0/1577.40.0.1 to 77.41.255.25477.41.255.255131,070
2277.42.0.0/1577.42.0.1 to 77.43.255.25477.43.255.255131,070
2377.44.0.0/1577.44.0.1 to 77.45.255.25477.45.255.255131,070
2477.46.0.0/1577.46.0.1 to 77.47.255.25477.47.255.255131,070
2577.48.0.0/1577.48.0.1 to 77.49.255.25477.49.255.255131,070
2677.50.0.0/1577.50.0.1 to 77.51.255.25477.51.255.255131,070
2777.52.0.0/1577.52.0.1 to 77.53.255.25477.53.255.255131,070
2877.54.0.0/1577.54.0.1 to 77.55.255.25477.55.255.255131,070
2977.56.0.0/1577.56.0.1 to 77.57.255.25477.57.255.255131,070
3077.58.0.0/1577.58.0.1 to 77.59.255.25477.59.255.255131,070
3177.60.0.0/1577.60.0.1 to 77.61.255.25477.61.255.255131,070
3277.62.0.0/1577.62.0.1 to 77.63.255.25477.63.255.255131,070
3377.64.0.0/1577.64.0.1 to 77.65.255.25477.65.255.255131,070
3477.66.0.0/1577.66.0.1 to 77.67.255.25477.67.255.255131,070
3577.68.0.0/1577.68.0.1 to 77.69.255.25477.69.255.255131,070
3677.70.0.0/1577.70.0.1 to 77.71.255.25477.71.255.255131,070
3777.72.0.0/1577.72.0.1 to 77.73.255.25477.73.255.255131,070
3877.74.0.0/1577.74.0.1 to 77.75.255.25477.75.255.255131,070
3977.76.0.0/1577.76.0.1 to 77.77.255.25477.77.255.255131,070
4077.78.0.0/1577.78.0.1 to 77.79.255.25477.79.255.255131,070
4177.80.0.0/1577.80.0.1 to 77.81.255.25477.81.255.255131,070
4277.82.0.0/1577.82.0.1 to 77.83.255.25477.83.255.255131,070
4377.84.0.0/1577.84.0.1 to 77.85.255.25477.85.255.255131,070
4477.86.0.0/1577.86.0.1 to 77.87.255.25477.87.255.255131,070
4577.88.0.0/1577.88.0.1 to 77.89.255.25477.89.255.255131,070
4677.90.0.0/1577.90.0.1 to 77.91.255.25477.91.255.255131,070
4777.92.0.0/1577.92.0.1 to 77.93.255.25477.93.255.255131,070
4877.94.0.0/1577.94.0.1 to 77.95.255.25477.95.255.255131,070
4977.96.0.0/1577.96.0.1 to 77.97.255.25477.97.255.255131,070
5077.98.0.0/1577.98.0.1 to 77.99.255.25477.99.255.255131,070
5177.100.0.0/1577.100.0.1 to 77.101.255.25477.101.255.255131,070
5277.102.0.0/1577.102.0.1 to 77.103.255.25477.103.255.255131,070
5377.104.0.0/1577.104.0.1 to 77.105.255.25477.105.255.255131,070
5477.106.0.0/1577.106.0.1 to 77.107.255.25477.107.255.255131,070
5577.108.0.0/1577.108.0.1 to 77.109.255.25477.109.255.255131,070
5677.110.0.0/1577.110.0.1 to 77.111.255.25477.111.255.255131,070
5777.112.0.0/1577.112.0.1 to 77.113.255.25477.113.255.255131,070
5877.114.0.0/1577.114.0.1 to 77.115.255.25477.115.255.255131,070
5977.116.0.0/1577.116.0.1 to 77.117.255.25477.117.255.255131,070
6077.118.0.0/1577.118.0.1 to 77.119.255.25477.119.255.255131,070
6177.120.0.0/1577.120.0.1 to 77.121.255.25477.121.255.255131,070
6277.122.0.0/1577.122.0.1 to 77.123.255.25477.123.255.255131,070
6377.124.0.0/1577.124.0.1 to 77.125.255.25477.125.255.255131,070
6477.126.0.0/1577.126.0.1 to 77.127.255.25477.127.255.255131,070

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.