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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.

Network65.200.0.0/13
Usable hosts524,286
Subnet mask255.248.0.0
Addresses524,288
Network address
65.200.0.0
Broadcast address
65.207.255.255
First usable
65.200.0.1
Last usable
65.207.255.254
Usable hosts
524,286 (524,288 less the network and broadcast addresses)
Subnet mask
255.248.0.0
Wildcard mask
0.7.255.255 (Cisco ACLs, OSPF)
Prefix length
/13
Type
Public public
Old class
A (default /8)
As numbers
Hex 41C80000 · Integer 1103626240 to 1104150527
Reverse DNS zones
200.65.in-addr.arpa
201.65.in-addr.arpa
202.65.in-addr.arpa
203.65.in-addr.arpa
204.65.in-addr.arpa
205.65.in-addr.arpa
206.65.in-addr.arpa
207.65.in-addr.arpa
/13 is not on a 8-bit boundary, so it takes 8 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01000001.11001000.00000000.0000000065.200.0.0
Subnet mask11111111.11111000.00000000.00000000255.248.0.0
Network01000001.11001000.00000000.0000000065.200.0.0
Broadcast01000001.11001111.11111111.1111111165.207.255.255
Split into smaller subnets/20
/14 (2)/15 (4)/16 (8)/17 (16)/18 (32)/19 (64)/20 (128)/21 (256)/22 (512)/23 (1,024)/24 (2,048)/25 (4,096)

65.200.0.0/13 makes 128 subnets of /20.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
165.200.0.0/2065.200.0.1 to 65.200.15.25465.200.15.2554,094
265.200.16.0/2065.200.16.1 to 65.200.31.25465.200.31.2554,094
365.200.32.0/2065.200.32.1 to 65.200.47.25465.200.47.2554,094
465.200.48.0/2065.200.48.1 to 65.200.63.25465.200.63.2554,094
565.200.64.0/2065.200.64.1 to 65.200.79.25465.200.79.2554,094
665.200.80.0/2065.200.80.1 to 65.200.95.25465.200.95.2554,094
765.200.96.0/2065.200.96.1 to 65.200.111.25465.200.111.2554,094
865.200.112.0/2065.200.112.1 to 65.200.127.25465.200.127.2554,094
965.200.128.0/2065.200.128.1 to 65.200.143.25465.200.143.2554,094
1065.200.144.0/2065.200.144.1 to 65.200.159.25465.200.159.2554,094
1165.200.160.0/2065.200.160.1 to 65.200.175.25465.200.175.2554,094
1265.200.176.0/2065.200.176.1 to 65.200.191.25465.200.191.2554,094
1365.200.192.0/2065.200.192.1 to 65.200.207.25465.200.207.2554,094
1465.200.208.0/2065.200.208.1 to 65.200.223.25465.200.223.2554,094
1565.200.224.0/2065.200.224.1 to 65.200.239.25465.200.239.2554,094
1665.200.240.0/2065.200.240.1 to 65.200.255.25465.200.255.2554,094
1765.201.0.0/2065.201.0.1 to 65.201.15.25465.201.15.2554,094
1865.201.16.0/2065.201.16.1 to 65.201.31.25465.201.31.2554,094
1965.201.32.0/2065.201.32.1 to 65.201.47.25465.201.47.2554,094
2065.201.48.0/2065.201.48.1 to 65.201.63.25465.201.63.2554,094
2165.201.64.0/2065.201.64.1 to 65.201.79.25465.201.79.2554,094
2265.201.80.0/2065.201.80.1 to 65.201.95.25465.201.95.2554,094
2365.201.96.0/2065.201.96.1 to 65.201.111.25465.201.111.2554,094
2465.201.112.0/2065.201.112.1 to 65.201.127.25465.201.127.2554,094
2565.201.128.0/2065.201.128.1 to 65.201.143.25465.201.143.2554,094
2665.201.144.0/2065.201.144.1 to 65.201.159.25465.201.159.2554,094
2765.201.160.0/2065.201.160.1 to 65.201.175.25465.201.175.2554,094
2865.201.176.0/2065.201.176.1 to 65.201.191.25465.201.191.2554,094
2965.201.192.0/2065.201.192.1 to 65.201.207.25465.201.207.2554,094
3065.201.208.0/2065.201.208.1 to 65.201.223.25465.201.223.2554,094
3165.201.224.0/2065.201.224.1 to 65.201.239.25465.201.239.2554,094
3265.201.240.0/2065.201.240.1 to 65.201.255.25465.201.255.2554,094
3365.202.0.0/2065.202.0.1 to 65.202.15.25465.202.15.2554,094
3465.202.16.0/2065.202.16.1 to 65.202.31.25465.202.31.2554,094
3565.202.32.0/2065.202.32.1 to 65.202.47.25465.202.47.2554,094
3665.202.48.0/2065.202.48.1 to 65.202.63.25465.202.63.2554,094
3765.202.64.0/2065.202.64.1 to 65.202.79.25465.202.79.2554,094
3865.202.80.0/2065.202.80.1 to 65.202.95.25465.202.95.2554,094
3965.202.96.0/2065.202.96.1 to 65.202.111.25465.202.111.2554,094
4065.202.112.0/2065.202.112.1 to 65.202.127.25465.202.127.2554,094
4165.202.128.0/2065.202.128.1 to 65.202.143.25465.202.143.2554,094
4265.202.144.0/2065.202.144.1 to 65.202.159.25465.202.159.2554,094
4365.202.160.0/2065.202.160.1 to 65.202.175.25465.202.175.2554,094
4465.202.176.0/2065.202.176.1 to 65.202.191.25465.202.191.2554,094
4565.202.192.0/2065.202.192.1 to 65.202.207.25465.202.207.2554,094
4665.202.208.0/2065.202.208.1 to 65.202.223.25465.202.223.2554,094
4765.202.224.0/2065.202.224.1 to 65.202.239.25465.202.239.2554,094
4865.202.240.0/2065.202.240.1 to 65.202.255.25465.202.255.2554,094
4965.203.0.0/2065.203.0.1 to 65.203.15.25465.203.15.2554,094
5065.203.16.0/2065.203.16.1 to 65.203.31.25465.203.31.2554,094
5165.203.32.0/2065.203.32.1 to 65.203.47.25465.203.47.2554,094
5265.203.48.0/2065.203.48.1 to 65.203.63.25465.203.63.2554,094
5365.203.64.0/2065.203.64.1 to 65.203.79.25465.203.79.2554,094
5465.203.80.0/2065.203.80.1 to 65.203.95.25465.203.95.2554,094
5565.203.96.0/2065.203.96.1 to 65.203.111.25465.203.111.2554,094
5665.203.112.0/2065.203.112.1 to 65.203.127.25465.203.127.2554,094
5765.203.128.0/2065.203.128.1 to 65.203.143.25465.203.143.2554,094
5865.203.144.0/2065.203.144.1 to 65.203.159.25465.203.159.2554,094
5965.203.160.0/2065.203.160.1 to 65.203.175.25465.203.175.2554,094
6065.203.176.0/2065.203.176.1 to 65.203.191.25465.203.191.2554,094
6165.203.192.0/2065.203.192.1 to 65.203.207.25465.203.207.2554,094
6265.203.208.0/2065.203.208.1 to 65.203.223.25465.203.223.2554,094
6365.203.224.0/2065.203.224.1 to 65.203.239.25465.203.239.2554,094
6465.203.240.0/2065.203.240.1 to 65.203.255.25465.203.255.2554,094
6565.204.0.0/2065.204.0.1 to 65.204.15.25465.204.15.2554,094
6665.204.16.0/2065.204.16.1 to 65.204.31.25465.204.31.2554,094
6765.204.32.0/2065.204.32.1 to 65.204.47.25465.204.47.2554,094
6865.204.48.0/2065.204.48.1 to 65.204.63.25465.204.63.2554,094
6965.204.64.0/2065.204.64.1 to 65.204.79.25465.204.79.2554,094
7065.204.80.0/2065.204.80.1 to 65.204.95.25465.204.95.2554,094
7165.204.96.0/2065.204.96.1 to 65.204.111.25465.204.111.2554,094
7265.204.112.0/2065.204.112.1 to 65.204.127.25465.204.127.2554,094
7365.204.128.0/2065.204.128.1 to 65.204.143.25465.204.143.2554,094
7465.204.144.0/2065.204.144.1 to 65.204.159.25465.204.159.2554,094
7565.204.160.0/2065.204.160.1 to 65.204.175.25465.204.175.2554,094
7665.204.176.0/2065.204.176.1 to 65.204.191.25465.204.191.2554,094
7765.204.192.0/2065.204.192.1 to 65.204.207.25465.204.207.2554,094
7865.204.208.0/2065.204.208.1 to 65.204.223.25465.204.223.2554,094
7965.204.224.0/2065.204.224.1 to 65.204.239.25465.204.239.2554,094
8065.204.240.0/2065.204.240.1 to 65.204.255.25465.204.255.2554,094
8165.205.0.0/2065.205.0.1 to 65.205.15.25465.205.15.2554,094
8265.205.16.0/2065.205.16.1 to 65.205.31.25465.205.31.2554,094
8365.205.32.0/2065.205.32.1 to 65.205.47.25465.205.47.2554,094
8465.205.48.0/2065.205.48.1 to 65.205.63.25465.205.63.2554,094
8565.205.64.0/2065.205.64.1 to 65.205.79.25465.205.79.2554,094
8665.205.80.0/2065.205.80.1 to 65.205.95.25465.205.95.2554,094
8765.205.96.0/2065.205.96.1 to 65.205.111.25465.205.111.2554,094
8865.205.112.0/2065.205.112.1 to 65.205.127.25465.205.127.2554,094
8965.205.128.0/2065.205.128.1 to 65.205.143.25465.205.143.2554,094
9065.205.144.0/2065.205.144.1 to 65.205.159.25465.205.159.2554,094
9165.205.160.0/2065.205.160.1 to 65.205.175.25465.205.175.2554,094
9265.205.176.0/2065.205.176.1 to 65.205.191.25465.205.191.2554,094
9365.205.192.0/2065.205.192.1 to 65.205.207.25465.205.207.2554,094
9465.205.208.0/2065.205.208.1 to 65.205.223.25465.205.223.2554,094
9565.205.224.0/2065.205.224.1 to 65.205.239.25465.205.239.2554,094
9665.205.240.0/2065.205.240.1 to 65.205.255.25465.205.255.2554,094
9765.206.0.0/2065.206.0.1 to 65.206.15.25465.206.15.2554,094
9865.206.16.0/2065.206.16.1 to 65.206.31.25465.206.31.2554,094
9965.206.32.0/2065.206.32.1 to 65.206.47.25465.206.47.2554,094
10065.206.48.0/2065.206.48.1 to 65.206.63.25465.206.63.2554,094
10165.206.64.0/2065.206.64.1 to 65.206.79.25465.206.79.2554,094
10265.206.80.0/2065.206.80.1 to 65.206.95.25465.206.95.2554,094
10365.206.96.0/2065.206.96.1 to 65.206.111.25465.206.111.2554,094
10465.206.112.0/2065.206.112.1 to 65.206.127.25465.206.127.2554,094
10565.206.128.0/2065.206.128.1 to 65.206.143.25465.206.143.2554,094
10665.206.144.0/2065.206.144.1 to 65.206.159.25465.206.159.2554,094
10765.206.160.0/2065.206.160.1 to 65.206.175.25465.206.175.2554,094
10865.206.176.0/2065.206.176.1 to 65.206.191.25465.206.191.2554,094
10965.206.192.0/2065.206.192.1 to 65.206.207.25465.206.207.2554,094
11065.206.208.0/2065.206.208.1 to 65.206.223.25465.206.223.2554,094
11165.206.224.0/2065.206.224.1 to 65.206.239.25465.206.239.2554,094
11265.206.240.0/2065.206.240.1 to 65.206.255.25465.206.255.2554,094
11365.207.0.0/2065.207.0.1 to 65.207.15.25465.207.15.2554,094
11465.207.16.0/2065.207.16.1 to 65.207.31.25465.207.31.2554,094
11565.207.32.0/2065.207.32.1 to 65.207.47.25465.207.47.2554,094
11665.207.48.0/2065.207.48.1 to 65.207.63.25465.207.63.2554,094
11765.207.64.0/2065.207.64.1 to 65.207.79.25465.207.79.2554,094
11865.207.80.0/2065.207.80.1 to 65.207.95.25465.207.95.2554,094
11965.207.96.0/2065.207.96.1 to 65.207.111.25465.207.111.2554,094
12065.207.112.0/2065.207.112.1 to 65.207.127.25465.207.127.2554,094
12165.207.128.0/2065.207.128.1 to 65.207.143.25465.207.143.2554,094
12265.207.144.0/2065.207.144.1 to 65.207.159.25465.207.159.2554,094
12365.207.160.0/2065.207.160.1 to 65.207.175.25465.207.175.2554,094
12465.207.176.0/2065.207.176.1 to 65.207.191.25465.207.191.2554,094
12565.207.192.0/2065.207.192.1 to 65.207.207.25465.207.207.2554,094
12665.207.208.0/2065.207.208.1 to 65.207.223.25465.207.223.2554,094
12765.207.224.0/2065.207.224.1 to 65.207.239.25465.207.239.2554,094
12865.207.240.0/2065.207.240.1 to 65.207.255.25465.207.255.2554,094

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.