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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.

Network26.65.0.0/16
Usable hosts65,534
Subnet mask255.255.0.0
Addresses65,536
Network address
26.65.0.0
Broadcast address
26.65.255.255
First usable
26.65.0.1
Last usable
26.65.255.254
Usable hosts
65,534 (65,536 less the network and broadcast addresses)
Subnet mask
255.255.0.0
Wildcard mask
0.0.255.255 (Cisco ACLs, OSPF)
Prefix length
/16
Type
Public public
Old class
A (default /8)
As numbers
Hex 1A410000 · Integer 440467456 to 440532991
Reverse DNS zone
65.26.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00011010.01000001..00000000.0000000026.65.0.0
Subnet mask11111111.11111111..00000000.00000000255.255.0.0
Network00011010.01000001..00000000.0000000026.65.0.0
Broadcast00011010.01000001..11111111.1111111126.65.255.255
Split into smaller subnets/23
/17 (2)/18 (4)/19 (8)/20 (16)/21 (32)/22 (64)/23 (128)/24 (256)/25 (512)/26 (1,024)/27 (2,048)/28 (4,096)

26.65.0.0/16 makes 128 subnets of /23.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
126.65.0.0/2326.65.0.1 to 26.65.1.25426.65.1.255510
226.65.2.0/2326.65.2.1 to 26.65.3.25426.65.3.255510
326.65.4.0/2326.65.4.1 to 26.65.5.25426.65.5.255510
426.65.6.0/2326.65.6.1 to 26.65.7.25426.65.7.255510
526.65.8.0/2326.65.8.1 to 26.65.9.25426.65.9.255510
626.65.10.0/2326.65.10.1 to 26.65.11.25426.65.11.255510
726.65.12.0/2326.65.12.1 to 26.65.13.25426.65.13.255510
826.65.14.0/2326.65.14.1 to 26.65.15.25426.65.15.255510
926.65.16.0/2326.65.16.1 to 26.65.17.25426.65.17.255510
1026.65.18.0/2326.65.18.1 to 26.65.19.25426.65.19.255510
1126.65.20.0/2326.65.20.1 to 26.65.21.25426.65.21.255510
1226.65.22.0/2326.65.22.1 to 26.65.23.25426.65.23.255510
1326.65.24.0/2326.65.24.1 to 26.65.25.25426.65.25.255510
1426.65.26.0/2326.65.26.1 to 26.65.27.25426.65.27.255510
1526.65.28.0/2326.65.28.1 to 26.65.29.25426.65.29.255510
1626.65.30.0/2326.65.30.1 to 26.65.31.25426.65.31.255510
1726.65.32.0/2326.65.32.1 to 26.65.33.25426.65.33.255510
1826.65.34.0/2326.65.34.1 to 26.65.35.25426.65.35.255510
1926.65.36.0/2326.65.36.1 to 26.65.37.25426.65.37.255510
2026.65.38.0/2326.65.38.1 to 26.65.39.25426.65.39.255510
2126.65.40.0/2326.65.40.1 to 26.65.41.25426.65.41.255510
2226.65.42.0/2326.65.42.1 to 26.65.43.25426.65.43.255510
2326.65.44.0/2326.65.44.1 to 26.65.45.25426.65.45.255510
2426.65.46.0/2326.65.46.1 to 26.65.47.25426.65.47.255510
2526.65.48.0/2326.65.48.1 to 26.65.49.25426.65.49.255510
2626.65.50.0/2326.65.50.1 to 26.65.51.25426.65.51.255510
2726.65.52.0/2326.65.52.1 to 26.65.53.25426.65.53.255510
2826.65.54.0/2326.65.54.1 to 26.65.55.25426.65.55.255510
2926.65.56.0/2326.65.56.1 to 26.65.57.25426.65.57.255510
3026.65.58.0/2326.65.58.1 to 26.65.59.25426.65.59.255510
3126.65.60.0/2326.65.60.1 to 26.65.61.25426.65.61.255510
3226.65.62.0/2326.65.62.1 to 26.65.63.25426.65.63.255510
3326.65.64.0/2326.65.64.1 to 26.65.65.25426.65.65.255510
3426.65.66.0/2326.65.66.1 to 26.65.67.25426.65.67.255510
3526.65.68.0/2326.65.68.1 to 26.65.69.25426.65.69.255510
3626.65.70.0/2326.65.70.1 to 26.65.71.25426.65.71.255510
3726.65.72.0/2326.65.72.1 to 26.65.73.25426.65.73.255510
3826.65.74.0/2326.65.74.1 to 26.65.75.25426.65.75.255510
3926.65.76.0/2326.65.76.1 to 26.65.77.25426.65.77.255510
4026.65.78.0/2326.65.78.1 to 26.65.79.25426.65.79.255510
4126.65.80.0/2326.65.80.1 to 26.65.81.25426.65.81.255510
4226.65.82.0/2326.65.82.1 to 26.65.83.25426.65.83.255510
4326.65.84.0/2326.65.84.1 to 26.65.85.25426.65.85.255510
4426.65.86.0/2326.65.86.1 to 26.65.87.25426.65.87.255510
4526.65.88.0/2326.65.88.1 to 26.65.89.25426.65.89.255510
4626.65.90.0/2326.65.90.1 to 26.65.91.25426.65.91.255510
4726.65.92.0/2326.65.92.1 to 26.65.93.25426.65.93.255510
4826.65.94.0/2326.65.94.1 to 26.65.95.25426.65.95.255510
4926.65.96.0/2326.65.96.1 to 26.65.97.25426.65.97.255510
5026.65.98.0/2326.65.98.1 to 26.65.99.25426.65.99.255510
5126.65.100.0/2326.65.100.1 to 26.65.101.25426.65.101.255510
5226.65.102.0/2326.65.102.1 to 26.65.103.25426.65.103.255510
5326.65.104.0/2326.65.104.1 to 26.65.105.25426.65.105.255510
5426.65.106.0/2326.65.106.1 to 26.65.107.25426.65.107.255510
5526.65.108.0/2326.65.108.1 to 26.65.109.25426.65.109.255510
5626.65.110.0/2326.65.110.1 to 26.65.111.25426.65.111.255510
5726.65.112.0/2326.65.112.1 to 26.65.113.25426.65.113.255510
5826.65.114.0/2326.65.114.1 to 26.65.115.25426.65.115.255510
5926.65.116.0/2326.65.116.1 to 26.65.117.25426.65.117.255510
6026.65.118.0/2326.65.118.1 to 26.65.119.25426.65.119.255510
6126.65.120.0/2326.65.120.1 to 26.65.121.25426.65.121.255510
6226.65.122.0/2326.65.122.1 to 26.65.123.25426.65.123.255510
6326.65.124.0/2326.65.124.1 to 26.65.125.25426.65.125.255510
6426.65.126.0/2326.65.126.1 to 26.65.127.25426.65.127.255510
6526.65.128.0/2326.65.128.1 to 26.65.129.25426.65.129.255510
6626.65.130.0/2326.65.130.1 to 26.65.131.25426.65.131.255510
6726.65.132.0/2326.65.132.1 to 26.65.133.25426.65.133.255510
6826.65.134.0/2326.65.134.1 to 26.65.135.25426.65.135.255510
6926.65.136.0/2326.65.136.1 to 26.65.137.25426.65.137.255510
7026.65.138.0/2326.65.138.1 to 26.65.139.25426.65.139.255510
7126.65.140.0/2326.65.140.1 to 26.65.141.25426.65.141.255510
7226.65.142.0/2326.65.142.1 to 26.65.143.25426.65.143.255510
7326.65.144.0/2326.65.144.1 to 26.65.145.25426.65.145.255510
7426.65.146.0/2326.65.146.1 to 26.65.147.25426.65.147.255510
7526.65.148.0/2326.65.148.1 to 26.65.149.25426.65.149.255510
7626.65.150.0/2326.65.150.1 to 26.65.151.25426.65.151.255510
7726.65.152.0/2326.65.152.1 to 26.65.153.25426.65.153.255510
7826.65.154.0/2326.65.154.1 to 26.65.155.25426.65.155.255510
7926.65.156.0/2326.65.156.1 to 26.65.157.25426.65.157.255510
8026.65.158.0/2326.65.158.1 to 26.65.159.25426.65.159.255510
8126.65.160.0/2326.65.160.1 to 26.65.161.25426.65.161.255510
8226.65.162.0/2326.65.162.1 to 26.65.163.25426.65.163.255510
8326.65.164.0/2326.65.164.1 to 26.65.165.25426.65.165.255510
8426.65.166.0/2326.65.166.1 to 26.65.167.25426.65.167.255510
8526.65.168.0/2326.65.168.1 to 26.65.169.25426.65.169.255510
8626.65.170.0/2326.65.170.1 to 26.65.171.25426.65.171.255510
8726.65.172.0/2326.65.172.1 to 26.65.173.25426.65.173.255510
8826.65.174.0/2326.65.174.1 to 26.65.175.25426.65.175.255510
8926.65.176.0/2326.65.176.1 to 26.65.177.25426.65.177.255510
9026.65.178.0/2326.65.178.1 to 26.65.179.25426.65.179.255510
9126.65.180.0/2326.65.180.1 to 26.65.181.25426.65.181.255510
9226.65.182.0/2326.65.182.1 to 26.65.183.25426.65.183.255510
9326.65.184.0/2326.65.184.1 to 26.65.185.25426.65.185.255510
9426.65.186.0/2326.65.186.1 to 26.65.187.25426.65.187.255510
9526.65.188.0/2326.65.188.1 to 26.65.189.25426.65.189.255510
9626.65.190.0/2326.65.190.1 to 26.65.191.25426.65.191.255510
9726.65.192.0/2326.65.192.1 to 26.65.193.25426.65.193.255510
9826.65.194.0/2326.65.194.1 to 26.65.195.25426.65.195.255510
9926.65.196.0/2326.65.196.1 to 26.65.197.25426.65.197.255510
10026.65.198.0/2326.65.198.1 to 26.65.199.25426.65.199.255510
10126.65.200.0/2326.65.200.1 to 26.65.201.25426.65.201.255510
10226.65.202.0/2326.65.202.1 to 26.65.203.25426.65.203.255510
10326.65.204.0/2326.65.204.1 to 26.65.205.25426.65.205.255510
10426.65.206.0/2326.65.206.1 to 26.65.207.25426.65.207.255510
10526.65.208.0/2326.65.208.1 to 26.65.209.25426.65.209.255510
10626.65.210.0/2326.65.210.1 to 26.65.211.25426.65.211.255510
10726.65.212.0/2326.65.212.1 to 26.65.213.25426.65.213.255510
10826.65.214.0/2326.65.214.1 to 26.65.215.25426.65.215.255510
10926.65.216.0/2326.65.216.1 to 26.65.217.25426.65.217.255510
11026.65.218.0/2326.65.218.1 to 26.65.219.25426.65.219.255510
11126.65.220.0/2326.65.220.1 to 26.65.221.25426.65.221.255510
11226.65.222.0/2326.65.222.1 to 26.65.223.25426.65.223.255510
11326.65.224.0/2326.65.224.1 to 26.65.225.25426.65.225.255510
11426.65.226.0/2326.65.226.1 to 26.65.227.25426.65.227.255510
11526.65.228.0/2326.65.228.1 to 26.65.229.25426.65.229.255510
11626.65.230.0/2326.65.230.1 to 26.65.231.25426.65.231.255510
11726.65.232.0/2326.65.232.1 to 26.65.233.25426.65.233.255510
11826.65.234.0/2326.65.234.1 to 26.65.235.25426.65.235.255510
11926.65.236.0/2326.65.236.1 to 26.65.237.25426.65.237.255510
12026.65.238.0/2326.65.238.1 to 26.65.239.25426.65.239.255510
12126.65.240.0/2326.65.240.1 to 26.65.241.25426.65.241.255510
12226.65.242.0/2326.65.242.1 to 26.65.243.25426.65.243.255510
12326.65.244.0/2326.65.244.1 to 26.65.245.25426.65.245.255510
12426.65.246.0/2326.65.246.1 to 26.65.247.25426.65.247.255510
12526.65.248.0/2326.65.248.1 to 26.65.249.25426.65.249.255510
12626.65.250.0/2326.65.250.1 to 26.65.251.25426.65.251.255510
12726.65.252.0/2326.65.252.1 to 26.65.253.25426.65.253.255510
12826.65.254.0/2326.65.254.1 to 26.65.255.25426.65.255.255510

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.