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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.

Network50.64.0.0/17
Usable hosts32,766
Subnet mask255.255.128.0
Addresses32,768
Network address
50.64.0.0
Broadcast address
50.64.127.255
First usable
50.64.0.1
Last usable
50.64.127.254
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 32400000 · Integer 843055104 to 843087871
Reverse DNS zones
0.64.50.in-addr.arpa
1.64.50.in-addr.arpa
2.64.50.in-addr.arpa
3.64.50.in-addr.arpa
4.64.50.in-addr.arpa
5.64.50.in-addr.arpa
6.64.50.in-addr.arpa
7.64.50.in-addr.arpa
8.64.50.in-addr.arpa
9.64.50.in-addr.arpa
10.64.50.in-addr.arpa
11.64.50.in-addr.arpa
12.64.50.in-addr.arpa
13.64.50.in-addr.arpa
14.64.50.in-addr.arpa
15.64.50.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
Address00110010.01000000.00000000.0000000050.64.0.0
Subnet mask11111111.11111111.10000000.00000000255.255.128.0
Network00110010.01000000.00000000.0000000050.64.0.0
Broadcast00110010.01000000.01111111.1111111150.64.127.255
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)

50.64.0.0/17 makes 128 subnets of /24.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
150.64.0.0/2450.64.0.1 to 50.64.0.25450.64.0.255254
250.64.1.0/2450.64.1.1 to 50.64.1.25450.64.1.255254
350.64.2.0/2450.64.2.1 to 50.64.2.25450.64.2.255254
450.64.3.0/2450.64.3.1 to 50.64.3.25450.64.3.255254
550.64.4.0/2450.64.4.1 to 50.64.4.25450.64.4.255254
650.64.5.0/2450.64.5.1 to 50.64.5.25450.64.5.255254
750.64.6.0/2450.64.6.1 to 50.64.6.25450.64.6.255254
850.64.7.0/2450.64.7.1 to 50.64.7.25450.64.7.255254
950.64.8.0/2450.64.8.1 to 50.64.8.25450.64.8.255254
1050.64.9.0/2450.64.9.1 to 50.64.9.25450.64.9.255254
1150.64.10.0/2450.64.10.1 to 50.64.10.25450.64.10.255254
1250.64.11.0/2450.64.11.1 to 50.64.11.25450.64.11.255254
1350.64.12.0/2450.64.12.1 to 50.64.12.25450.64.12.255254
1450.64.13.0/2450.64.13.1 to 50.64.13.25450.64.13.255254
1550.64.14.0/2450.64.14.1 to 50.64.14.25450.64.14.255254
1650.64.15.0/2450.64.15.1 to 50.64.15.25450.64.15.255254
1750.64.16.0/2450.64.16.1 to 50.64.16.25450.64.16.255254
1850.64.17.0/2450.64.17.1 to 50.64.17.25450.64.17.255254
1950.64.18.0/2450.64.18.1 to 50.64.18.25450.64.18.255254
2050.64.19.0/2450.64.19.1 to 50.64.19.25450.64.19.255254
2150.64.20.0/2450.64.20.1 to 50.64.20.25450.64.20.255254
2250.64.21.0/2450.64.21.1 to 50.64.21.25450.64.21.255254
2350.64.22.0/2450.64.22.1 to 50.64.22.25450.64.22.255254
2450.64.23.0/2450.64.23.1 to 50.64.23.25450.64.23.255254
2550.64.24.0/2450.64.24.1 to 50.64.24.25450.64.24.255254
2650.64.25.0/2450.64.25.1 to 50.64.25.25450.64.25.255254
2750.64.26.0/2450.64.26.1 to 50.64.26.25450.64.26.255254
2850.64.27.0/2450.64.27.1 to 50.64.27.25450.64.27.255254
2950.64.28.0/2450.64.28.1 to 50.64.28.25450.64.28.255254
3050.64.29.0/2450.64.29.1 to 50.64.29.25450.64.29.255254
3150.64.30.0/2450.64.30.1 to 50.64.30.25450.64.30.255254
3250.64.31.0/2450.64.31.1 to 50.64.31.25450.64.31.255254
3350.64.32.0/2450.64.32.1 to 50.64.32.25450.64.32.255254
3450.64.33.0/2450.64.33.1 to 50.64.33.25450.64.33.255254
3550.64.34.0/2450.64.34.1 to 50.64.34.25450.64.34.255254
3650.64.35.0/2450.64.35.1 to 50.64.35.25450.64.35.255254
3750.64.36.0/2450.64.36.1 to 50.64.36.25450.64.36.255254
3850.64.37.0/2450.64.37.1 to 50.64.37.25450.64.37.255254
3950.64.38.0/2450.64.38.1 to 50.64.38.25450.64.38.255254
4050.64.39.0/2450.64.39.1 to 50.64.39.25450.64.39.255254
4150.64.40.0/2450.64.40.1 to 50.64.40.25450.64.40.255254
4250.64.41.0/2450.64.41.1 to 50.64.41.25450.64.41.255254
4350.64.42.0/2450.64.42.1 to 50.64.42.25450.64.42.255254
4450.64.43.0/2450.64.43.1 to 50.64.43.25450.64.43.255254
4550.64.44.0/2450.64.44.1 to 50.64.44.25450.64.44.255254
4650.64.45.0/2450.64.45.1 to 50.64.45.25450.64.45.255254
4750.64.46.0/2450.64.46.1 to 50.64.46.25450.64.46.255254
4850.64.47.0/2450.64.47.1 to 50.64.47.25450.64.47.255254
4950.64.48.0/2450.64.48.1 to 50.64.48.25450.64.48.255254
5050.64.49.0/2450.64.49.1 to 50.64.49.25450.64.49.255254
5150.64.50.0/2450.64.50.1 to 50.64.50.25450.64.50.255254
5250.64.51.0/2450.64.51.1 to 50.64.51.25450.64.51.255254
5350.64.52.0/2450.64.52.1 to 50.64.52.25450.64.52.255254
5450.64.53.0/2450.64.53.1 to 50.64.53.25450.64.53.255254
5550.64.54.0/2450.64.54.1 to 50.64.54.25450.64.54.255254
5650.64.55.0/2450.64.55.1 to 50.64.55.25450.64.55.255254
5750.64.56.0/2450.64.56.1 to 50.64.56.25450.64.56.255254
5850.64.57.0/2450.64.57.1 to 50.64.57.25450.64.57.255254
5950.64.58.0/2450.64.58.1 to 50.64.58.25450.64.58.255254
6050.64.59.0/2450.64.59.1 to 50.64.59.25450.64.59.255254
6150.64.60.0/2450.64.60.1 to 50.64.60.25450.64.60.255254
6250.64.61.0/2450.64.61.1 to 50.64.61.25450.64.61.255254
6350.64.62.0/2450.64.62.1 to 50.64.62.25450.64.62.255254
6450.64.63.0/2450.64.63.1 to 50.64.63.25450.64.63.255254
6550.64.64.0/2450.64.64.1 to 50.64.64.25450.64.64.255254
6650.64.65.0/2450.64.65.1 to 50.64.65.25450.64.65.255254
6750.64.66.0/2450.64.66.1 to 50.64.66.25450.64.66.255254
6850.64.67.0/2450.64.67.1 to 50.64.67.25450.64.67.255254
6950.64.68.0/2450.64.68.1 to 50.64.68.25450.64.68.255254
7050.64.69.0/2450.64.69.1 to 50.64.69.25450.64.69.255254
7150.64.70.0/2450.64.70.1 to 50.64.70.25450.64.70.255254
7250.64.71.0/2450.64.71.1 to 50.64.71.25450.64.71.255254
7350.64.72.0/2450.64.72.1 to 50.64.72.25450.64.72.255254
7450.64.73.0/2450.64.73.1 to 50.64.73.25450.64.73.255254
7550.64.74.0/2450.64.74.1 to 50.64.74.25450.64.74.255254
7650.64.75.0/2450.64.75.1 to 50.64.75.25450.64.75.255254
7750.64.76.0/2450.64.76.1 to 50.64.76.25450.64.76.255254
7850.64.77.0/2450.64.77.1 to 50.64.77.25450.64.77.255254
7950.64.78.0/2450.64.78.1 to 50.64.78.25450.64.78.255254
8050.64.79.0/2450.64.79.1 to 50.64.79.25450.64.79.255254
8150.64.80.0/2450.64.80.1 to 50.64.80.25450.64.80.255254
8250.64.81.0/2450.64.81.1 to 50.64.81.25450.64.81.255254
8350.64.82.0/2450.64.82.1 to 50.64.82.25450.64.82.255254
8450.64.83.0/2450.64.83.1 to 50.64.83.25450.64.83.255254
8550.64.84.0/2450.64.84.1 to 50.64.84.25450.64.84.255254
8650.64.85.0/2450.64.85.1 to 50.64.85.25450.64.85.255254
8750.64.86.0/2450.64.86.1 to 50.64.86.25450.64.86.255254
8850.64.87.0/2450.64.87.1 to 50.64.87.25450.64.87.255254
8950.64.88.0/2450.64.88.1 to 50.64.88.25450.64.88.255254
9050.64.89.0/2450.64.89.1 to 50.64.89.25450.64.89.255254
9150.64.90.0/2450.64.90.1 to 50.64.90.25450.64.90.255254
9250.64.91.0/2450.64.91.1 to 50.64.91.25450.64.91.255254
9350.64.92.0/2450.64.92.1 to 50.64.92.25450.64.92.255254
9450.64.93.0/2450.64.93.1 to 50.64.93.25450.64.93.255254
9550.64.94.0/2450.64.94.1 to 50.64.94.25450.64.94.255254
9650.64.95.0/2450.64.95.1 to 50.64.95.25450.64.95.255254
9750.64.96.0/2450.64.96.1 to 50.64.96.25450.64.96.255254
9850.64.97.0/2450.64.97.1 to 50.64.97.25450.64.97.255254
9950.64.98.0/2450.64.98.1 to 50.64.98.25450.64.98.255254
10050.64.99.0/2450.64.99.1 to 50.64.99.25450.64.99.255254
10150.64.100.0/2450.64.100.1 to 50.64.100.25450.64.100.255254
10250.64.101.0/2450.64.101.1 to 50.64.101.25450.64.101.255254
10350.64.102.0/2450.64.102.1 to 50.64.102.25450.64.102.255254
10450.64.103.0/2450.64.103.1 to 50.64.103.25450.64.103.255254
10550.64.104.0/2450.64.104.1 to 50.64.104.25450.64.104.255254
10650.64.105.0/2450.64.105.1 to 50.64.105.25450.64.105.255254
10750.64.106.0/2450.64.106.1 to 50.64.106.25450.64.106.255254
10850.64.107.0/2450.64.107.1 to 50.64.107.25450.64.107.255254
10950.64.108.0/2450.64.108.1 to 50.64.108.25450.64.108.255254
11050.64.109.0/2450.64.109.1 to 50.64.109.25450.64.109.255254
11150.64.110.0/2450.64.110.1 to 50.64.110.25450.64.110.255254
11250.64.111.0/2450.64.111.1 to 50.64.111.25450.64.111.255254
11350.64.112.0/2450.64.112.1 to 50.64.112.25450.64.112.255254
11450.64.113.0/2450.64.113.1 to 50.64.113.25450.64.113.255254
11550.64.114.0/2450.64.114.1 to 50.64.114.25450.64.114.255254
11650.64.115.0/2450.64.115.1 to 50.64.115.25450.64.115.255254
11750.64.116.0/2450.64.116.1 to 50.64.116.25450.64.116.255254
11850.64.117.0/2450.64.117.1 to 50.64.117.25450.64.117.255254
11950.64.118.0/2450.64.118.1 to 50.64.118.25450.64.118.255254
12050.64.119.0/2450.64.119.1 to 50.64.119.25450.64.119.255254
12150.64.120.0/2450.64.120.1 to 50.64.120.25450.64.120.255254
12250.64.121.0/2450.64.121.1 to 50.64.121.25450.64.121.255254
12350.64.122.0/2450.64.122.1 to 50.64.122.25450.64.122.255254
12450.64.123.0/2450.64.123.1 to 50.64.123.25450.64.123.255254
12550.64.124.0/2450.64.124.1 to 50.64.124.25450.64.124.255254
12650.64.125.0/2450.64.125.1 to 50.64.125.25450.64.125.255254
12750.64.126.0/2450.64.126.1 to 50.64.126.25450.64.126.255254
12850.64.127.0/2450.64.127.1 to 50.64.127.25450.64.127.255254

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.