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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.

Network90.80.0.0/17
Usable hosts32,766
Subnet mask255.255.128.0
Addresses32,768
Network address
90.80.0.0
Broadcast address
90.80.127.255
First usable
90.80.0.1
Last usable
90.80.127.254
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 5A500000 · Integer 1515192320 to 1515225087
Reverse DNS zones
0.80.90.in-addr.arpa
1.80.90.in-addr.arpa
2.80.90.in-addr.arpa
3.80.90.in-addr.arpa
4.80.90.in-addr.arpa
5.80.90.in-addr.arpa
6.80.90.in-addr.arpa
7.80.90.in-addr.arpa
8.80.90.in-addr.arpa
9.80.90.in-addr.arpa
10.80.90.in-addr.arpa
11.80.90.in-addr.arpa
12.80.90.in-addr.arpa
13.80.90.in-addr.arpa
14.80.90.in-addr.arpa
15.80.90.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
Address01011010.01010000.00000000.0000000090.80.0.0
Subnet mask11111111.11111111.10000000.00000000255.255.128.0
Network01011010.01010000.00000000.0000000090.80.0.0
Broadcast01011010.01010000.01111111.1111111190.80.127.255
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)

90.80.0.0/17 makes 128 subnets of /24.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
190.80.0.0/2490.80.0.1 to 90.80.0.25490.80.0.255254
290.80.1.0/2490.80.1.1 to 90.80.1.25490.80.1.255254
390.80.2.0/2490.80.2.1 to 90.80.2.25490.80.2.255254
490.80.3.0/2490.80.3.1 to 90.80.3.25490.80.3.255254
590.80.4.0/2490.80.4.1 to 90.80.4.25490.80.4.255254
690.80.5.0/2490.80.5.1 to 90.80.5.25490.80.5.255254
790.80.6.0/2490.80.6.1 to 90.80.6.25490.80.6.255254
890.80.7.0/2490.80.7.1 to 90.80.7.25490.80.7.255254
990.80.8.0/2490.80.8.1 to 90.80.8.25490.80.8.255254
1090.80.9.0/2490.80.9.1 to 90.80.9.25490.80.9.255254
1190.80.10.0/2490.80.10.1 to 90.80.10.25490.80.10.255254
1290.80.11.0/2490.80.11.1 to 90.80.11.25490.80.11.255254
1390.80.12.0/2490.80.12.1 to 90.80.12.25490.80.12.255254
1490.80.13.0/2490.80.13.1 to 90.80.13.25490.80.13.255254
1590.80.14.0/2490.80.14.1 to 90.80.14.25490.80.14.255254
1690.80.15.0/2490.80.15.1 to 90.80.15.25490.80.15.255254
1790.80.16.0/2490.80.16.1 to 90.80.16.25490.80.16.255254
1890.80.17.0/2490.80.17.1 to 90.80.17.25490.80.17.255254
1990.80.18.0/2490.80.18.1 to 90.80.18.25490.80.18.255254
2090.80.19.0/2490.80.19.1 to 90.80.19.25490.80.19.255254
2190.80.20.0/2490.80.20.1 to 90.80.20.25490.80.20.255254
2290.80.21.0/2490.80.21.1 to 90.80.21.25490.80.21.255254
2390.80.22.0/2490.80.22.1 to 90.80.22.25490.80.22.255254
2490.80.23.0/2490.80.23.1 to 90.80.23.25490.80.23.255254
2590.80.24.0/2490.80.24.1 to 90.80.24.25490.80.24.255254
2690.80.25.0/2490.80.25.1 to 90.80.25.25490.80.25.255254
2790.80.26.0/2490.80.26.1 to 90.80.26.25490.80.26.255254
2890.80.27.0/2490.80.27.1 to 90.80.27.25490.80.27.255254
2990.80.28.0/2490.80.28.1 to 90.80.28.25490.80.28.255254
3090.80.29.0/2490.80.29.1 to 90.80.29.25490.80.29.255254
3190.80.30.0/2490.80.30.1 to 90.80.30.25490.80.30.255254
3290.80.31.0/2490.80.31.1 to 90.80.31.25490.80.31.255254
3390.80.32.0/2490.80.32.1 to 90.80.32.25490.80.32.255254
3490.80.33.0/2490.80.33.1 to 90.80.33.25490.80.33.255254
3590.80.34.0/2490.80.34.1 to 90.80.34.25490.80.34.255254
3690.80.35.0/2490.80.35.1 to 90.80.35.25490.80.35.255254
3790.80.36.0/2490.80.36.1 to 90.80.36.25490.80.36.255254
3890.80.37.0/2490.80.37.1 to 90.80.37.25490.80.37.255254
3990.80.38.0/2490.80.38.1 to 90.80.38.25490.80.38.255254
4090.80.39.0/2490.80.39.1 to 90.80.39.25490.80.39.255254
4190.80.40.0/2490.80.40.1 to 90.80.40.25490.80.40.255254
4290.80.41.0/2490.80.41.1 to 90.80.41.25490.80.41.255254
4390.80.42.0/2490.80.42.1 to 90.80.42.25490.80.42.255254
4490.80.43.0/2490.80.43.1 to 90.80.43.25490.80.43.255254
4590.80.44.0/2490.80.44.1 to 90.80.44.25490.80.44.255254
4690.80.45.0/2490.80.45.1 to 90.80.45.25490.80.45.255254
4790.80.46.0/2490.80.46.1 to 90.80.46.25490.80.46.255254
4890.80.47.0/2490.80.47.1 to 90.80.47.25490.80.47.255254
4990.80.48.0/2490.80.48.1 to 90.80.48.25490.80.48.255254
5090.80.49.0/2490.80.49.1 to 90.80.49.25490.80.49.255254
5190.80.50.0/2490.80.50.1 to 90.80.50.25490.80.50.255254
5290.80.51.0/2490.80.51.1 to 90.80.51.25490.80.51.255254
5390.80.52.0/2490.80.52.1 to 90.80.52.25490.80.52.255254
5490.80.53.0/2490.80.53.1 to 90.80.53.25490.80.53.255254
5590.80.54.0/2490.80.54.1 to 90.80.54.25490.80.54.255254
5690.80.55.0/2490.80.55.1 to 90.80.55.25490.80.55.255254
5790.80.56.0/2490.80.56.1 to 90.80.56.25490.80.56.255254
5890.80.57.0/2490.80.57.1 to 90.80.57.25490.80.57.255254
5990.80.58.0/2490.80.58.1 to 90.80.58.25490.80.58.255254
6090.80.59.0/2490.80.59.1 to 90.80.59.25490.80.59.255254
6190.80.60.0/2490.80.60.1 to 90.80.60.25490.80.60.255254
6290.80.61.0/2490.80.61.1 to 90.80.61.25490.80.61.255254
6390.80.62.0/2490.80.62.1 to 90.80.62.25490.80.62.255254
6490.80.63.0/2490.80.63.1 to 90.80.63.25490.80.63.255254
6590.80.64.0/2490.80.64.1 to 90.80.64.25490.80.64.255254
6690.80.65.0/2490.80.65.1 to 90.80.65.25490.80.65.255254
6790.80.66.0/2490.80.66.1 to 90.80.66.25490.80.66.255254
6890.80.67.0/2490.80.67.1 to 90.80.67.25490.80.67.255254
6990.80.68.0/2490.80.68.1 to 90.80.68.25490.80.68.255254
7090.80.69.0/2490.80.69.1 to 90.80.69.25490.80.69.255254
7190.80.70.0/2490.80.70.1 to 90.80.70.25490.80.70.255254
7290.80.71.0/2490.80.71.1 to 90.80.71.25490.80.71.255254
7390.80.72.0/2490.80.72.1 to 90.80.72.25490.80.72.255254
7490.80.73.0/2490.80.73.1 to 90.80.73.25490.80.73.255254
7590.80.74.0/2490.80.74.1 to 90.80.74.25490.80.74.255254
7690.80.75.0/2490.80.75.1 to 90.80.75.25490.80.75.255254
7790.80.76.0/2490.80.76.1 to 90.80.76.25490.80.76.255254
7890.80.77.0/2490.80.77.1 to 90.80.77.25490.80.77.255254
7990.80.78.0/2490.80.78.1 to 90.80.78.25490.80.78.255254
8090.80.79.0/2490.80.79.1 to 90.80.79.25490.80.79.255254
8190.80.80.0/2490.80.80.1 to 90.80.80.25490.80.80.255254
8290.80.81.0/2490.80.81.1 to 90.80.81.25490.80.81.255254
8390.80.82.0/2490.80.82.1 to 90.80.82.25490.80.82.255254
8490.80.83.0/2490.80.83.1 to 90.80.83.25490.80.83.255254
8590.80.84.0/2490.80.84.1 to 90.80.84.25490.80.84.255254
8690.80.85.0/2490.80.85.1 to 90.80.85.25490.80.85.255254
8790.80.86.0/2490.80.86.1 to 90.80.86.25490.80.86.255254
8890.80.87.0/2490.80.87.1 to 90.80.87.25490.80.87.255254
8990.80.88.0/2490.80.88.1 to 90.80.88.25490.80.88.255254
9090.80.89.0/2490.80.89.1 to 90.80.89.25490.80.89.255254
9190.80.90.0/2490.80.90.1 to 90.80.90.25490.80.90.255254
9290.80.91.0/2490.80.91.1 to 90.80.91.25490.80.91.255254
9390.80.92.0/2490.80.92.1 to 90.80.92.25490.80.92.255254
9490.80.93.0/2490.80.93.1 to 90.80.93.25490.80.93.255254
9590.80.94.0/2490.80.94.1 to 90.80.94.25490.80.94.255254
9690.80.95.0/2490.80.95.1 to 90.80.95.25490.80.95.255254
9790.80.96.0/2490.80.96.1 to 90.80.96.25490.80.96.255254
9890.80.97.0/2490.80.97.1 to 90.80.97.25490.80.97.255254
9990.80.98.0/2490.80.98.1 to 90.80.98.25490.80.98.255254
10090.80.99.0/2490.80.99.1 to 90.80.99.25490.80.99.255254
10190.80.100.0/2490.80.100.1 to 90.80.100.25490.80.100.255254
10290.80.101.0/2490.80.101.1 to 90.80.101.25490.80.101.255254
10390.80.102.0/2490.80.102.1 to 90.80.102.25490.80.102.255254
10490.80.103.0/2490.80.103.1 to 90.80.103.25490.80.103.255254
10590.80.104.0/2490.80.104.1 to 90.80.104.25490.80.104.255254
10690.80.105.0/2490.80.105.1 to 90.80.105.25490.80.105.255254
10790.80.106.0/2490.80.106.1 to 90.80.106.25490.80.106.255254
10890.80.107.0/2490.80.107.1 to 90.80.107.25490.80.107.255254
10990.80.108.0/2490.80.108.1 to 90.80.108.25490.80.108.255254
11090.80.109.0/2490.80.109.1 to 90.80.109.25490.80.109.255254
11190.80.110.0/2490.80.110.1 to 90.80.110.25490.80.110.255254
11290.80.111.0/2490.80.111.1 to 90.80.111.25490.80.111.255254
11390.80.112.0/2490.80.112.1 to 90.80.112.25490.80.112.255254
11490.80.113.0/2490.80.113.1 to 90.80.113.25490.80.113.255254
11590.80.114.0/2490.80.114.1 to 90.80.114.25490.80.114.255254
11690.80.115.0/2490.80.115.1 to 90.80.115.25490.80.115.255254
11790.80.116.0/2490.80.116.1 to 90.80.116.25490.80.116.255254
11890.80.117.0/2490.80.117.1 to 90.80.117.25490.80.117.255254
11990.80.118.0/2490.80.118.1 to 90.80.118.25490.80.118.255254
12090.80.119.0/2490.80.119.1 to 90.80.119.25490.80.119.255254
12190.80.120.0/2490.80.120.1 to 90.80.120.25490.80.120.255254
12290.80.121.0/2490.80.121.1 to 90.80.121.25490.80.121.255254
12390.80.122.0/2490.80.122.1 to 90.80.122.25490.80.122.255254
12490.80.123.0/2490.80.123.1 to 90.80.123.25490.80.123.255254
12590.80.124.0/2490.80.124.1 to 90.80.124.25490.80.124.255254
12690.80.125.0/2490.80.125.1 to 90.80.125.25490.80.125.255254
12790.80.126.0/2490.80.126.1 to 90.80.126.25490.80.126.255254
12890.80.127.0/2490.80.127.1 to 90.80.127.25490.80.127.255254

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.