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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.

Network65.192.0.0/10
Usable hosts4,194,302
Subnet mask255.192.0.0
Addresses4,194,304
Network address
65.192.0.0
Broadcast address
65.255.255.255
First usable
65.192.0.1
Last usable
65.255.255.254
Usable hosts
4,194,302 (4,194,304 less the network and broadcast addresses)
Subnet mask
255.192.0.0
Wildcard mask
0.63.255.255 (Cisco ACLs, OSPF)
Prefix length
/10
Type
Public public
Old class
A (default /8)
As numbers
Hex 41C00000 · Integer 1103101952 to 1107296255
Reverse DNS zones
192.65.in-addr.arpa
193.65.in-addr.arpa
194.65.in-addr.arpa
195.65.in-addr.arpa
196.65.in-addr.arpa
197.65.in-addr.arpa
198.65.in-addr.arpa
199.65.in-addr.arpa
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
and 48 more
/10 is not on a 8-bit boundary, so it takes 64 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01000001.11000000.00000000.0000000065.192.0.0
Subnet mask11111111.11000000.00000000.00000000255.192.0.0
Network01000001.11000000.00000000.0000000065.192.0.0
Broadcast01000001.11111111.11111111.1111111165.255.255.255
Split into smaller subnets/17
/11 (2)/12 (4)/13 (8)/14 (16)/15 (32)/16 (64)/17 (128)/18 (256)/19 (512)/20 (1,024)/21 (2,048)/22 (4,096)

65.192.0.0/10 makes 128 subnets of /17.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
165.192.0.0/1765.192.0.1 to 65.192.127.25465.192.127.25532,766
265.192.128.0/1765.192.128.1 to 65.192.255.25465.192.255.25532,766
365.193.0.0/1765.193.0.1 to 65.193.127.25465.193.127.25532,766
465.193.128.0/1765.193.128.1 to 65.193.255.25465.193.255.25532,766
565.194.0.0/1765.194.0.1 to 65.194.127.25465.194.127.25532,766
665.194.128.0/1765.194.128.1 to 65.194.255.25465.194.255.25532,766
765.195.0.0/1765.195.0.1 to 65.195.127.25465.195.127.25532,766
865.195.128.0/1765.195.128.1 to 65.195.255.25465.195.255.25532,766
965.196.0.0/1765.196.0.1 to 65.196.127.25465.196.127.25532,766
1065.196.128.0/1765.196.128.1 to 65.196.255.25465.196.255.25532,766
1165.197.0.0/1765.197.0.1 to 65.197.127.25465.197.127.25532,766
1265.197.128.0/1765.197.128.1 to 65.197.255.25465.197.255.25532,766
1365.198.0.0/1765.198.0.1 to 65.198.127.25465.198.127.25532,766
1465.198.128.0/1765.198.128.1 to 65.198.255.25465.198.255.25532,766
1565.199.0.0/1765.199.0.1 to 65.199.127.25465.199.127.25532,766
1665.199.128.0/1765.199.128.1 to 65.199.255.25465.199.255.25532,766
1765.200.0.0/1765.200.0.1 to 65.200.127.25465.200.127.25532,766
1865.200.128.0/1765.200.128.1 to 65.200.255.25465.200.255.25532,766
1965.201.0.0/1765.201.0.1 to 65.201.127.25465.201.127.25532,766
2065.201.128.0/1765.201.128.1 to 65.201.255.25465.201.255.25532,766
2165.202.0.0/1765.202.0.1 to 65.202.127.25465.202.127.25532,766
2265.202.128.0/1765.202.128.1 to 65.202.255.25465.202.255.25532,766
2365.203.0.0/1765.203.0.1 to 65.203.127.25465.203.127.25532,766
2465.203.128.0/1765.203.128.1 to 65.203.255.25465.203.255.25532,766
2565.204.0.0/1765.204.0.1 to 65.204.127.25465.204.127.25532,766
2665.204.128.0/1765.204.128.1 to 65.204.255.25465.204.255.25532,766
2765.205.0.0/1765.205.0.1 to 65.205.127.25465.205.127.25532,766
2865.205.128.0/1765.205.128.1 to 65.205.255.25465.205.255.25532,766
2965.206.0.0/1765.206.0.1 to 65.206.127.25465.206.127.25532,766
3065.206.128.0/1765.206.128.1 to 65.206.255.25465.206.255.25532,766
3165.207.0.0/1765.207.0.1 to 65.207.127.25465.207.127.25532,766
3265.207.128.0/1765.207.128.1 to 65.207.255.25465.207.255.25532,766
3365.208.0.0/1765.208.0.1 to 65.208.127.25465.208.127.25532,766
3465.208.128.0/1765.208.128.1 to 65.208.255.25465.208.255.25532,766
3565.209.0.0/1765.209.0.1 to 65.209.127.25465.209.127.25532,766
3665.209.128.0/1765.209.128.1 to 65.209.255.25465.209.255.25532,766
3765.210.0.0/1765.210.0.1 to 65.210.127.25465.210.127.25532,766
3865.210.128.0/1765.210.128.1 to 65.210.255.25465.210.255.25532,766
3965.211.0.0/1765.211.0.1 to 65.211.127.25465.211.127.25532,766
4065.211.128.0/1765.211.128.1 to 65.211.255.25465.211.255.25532,766
4165.212.0.0/1765.212.0.1 to 65.212.127.25465.212.127.25532,766
4265.212.128.0/1765.212.128.1 to 65.212.255.25465.212.255.25532,766
4365.213.0.0/1765.213.0.1 to 65.213.127.25465.213.127.25532,766
4465.213.128.0/1765.213.128.1 to 65.213.255.25465.213.255.25532,766
4565.214.0.0/1765.214.0.1 to 65.214.127.25465.214.127.25532,766
4665.214.128.0/1765.214.128.1 to 65.214.255.25465.214.255.25532,766
4765.215.0.0/1765.215.0.1 to 65.215.127.25465.215.127.25532,766
4865.215.128.0/1765.215.128.1 to 65.215.255.25465.215.255.25532,766
4965.216.0.0/1765.216.0.1 to 65.216.127.25465.216.127.25532,766
5065.216.128.0/1765.216.128.1 to 65.216.255.25465.216.255.25532,766
5165.217.0.0/1765.217.0.1 to 65.217.127.25465.217.127.25532,766
5265.217.128.0/1765.217.128.1 to 65.217.255.25465.217.255.25532,766
5365.218.0.0/1765.218.0.1 to 65.218.127.25465.218.127.25532,766
5465.218.128.0/1765.218.128.1 to 65.218.255.25465.218.255.25532,766
5565.219.0.0/1765.219.0.1 to 65.219.127.25465.219.127.25532,766
5665.219.128.0/1765.219.128.1 to 65.219.255.25465.219.255.25532,766
5765.220.0.0/1765.220.0.1 to 65.220.127.25465.220.127.25532,766
5865.220.128.0/1765.220.128.1 to 65.220.255.25465.220.255.25532,766
5965.221.0.0/1765.221.0.1 to 65.221.127.25465.221.127.25532,766
6065.221.128.0/1765.221.128.1 to 65.221.255.25465.221.255.25532,766
6165.222.0.0/1765.222.0.1 to 65.222.127.25465.222.127.25532,766
6265.222.128.0/1765.222.128.1 to 65.222.255.25465.222.255.25532,766
6365.223.0.0/1765.223.0.1 to 65.223.127.25465.223.127.25532,766
6465.223.128.0/1765.223.128.1 to 65.223.255.25465.223.255.25532,766
6565.224.0.0/1765.224.0.1 to 65.224.127.25465.224.127.25532,766
6665.224.128.0/1765.224.128.1 to 65.224.255.25465.224.255.25532,766
6765.225.0.0/1765.225.0.1 to 65.225.127.25465.225.127.25532,766
6865.225.128.0/1765.225.128.1 to 65.225.255.25465.225.255.25532,766
6965.226.0.0/1765.226.0.1 to 65.226.127.25465.226.127.25532,766
7065.226.128.0/1765.226.128.1 to 65.226.255.25465.226.255.25532,766
7165.227.0.0/1765.227.0.1 to 65.227.127.25465.227.127.25532,766
7265.227.128.0/1765.227.128.1 to 65.227.255.25465.227.255.25532,766
7365.228.0.0/1765.228.0.1 to 65.228.127.25465.228.127.25532,766
7465.228.128.0/1765.228.128.1 to 65.228.255.25465.228.255.25532,766
7565.229.0.0/1765.229.0.1 to 65.229.127.25465.229.127.25532,766
7665.229.128.0/1765.229.128.1 to 65.229.255.25465.229.255.25532,766
7765.230.0.0/1765.230.0.1 to 65.230.127.25465.230.127.25532,766
7865.230.128.0/1765.230.128.1 to 65.230.255.25465.230.255.25532,766
7965.231.0.0/1765.231.0.1 to 65.231.127.25465.231.127.25532,766
8065.231.128.0/1765.231.128.1 to 65.231.255.25465.231.255.25532,766
8165.232.0.0/1765.232.0.1 to 65.232.127.25465.232.127.25532,766
8265.232.128.0/1765.232.128.1 to 65.232.255.25465.232.255.25532,766
8365.233.0.0/1765.233.0.1 to 65.233.127.25465.233.127.25532,766
8465.233.128.0/1765.233.128.1 to 65.233.255.25465.233.255.25532,766
8565.234.0.0/1765.234.0.1 to 65.234.127.25465.234.127.25532,766
8665.234.128.0/1765.234.128.1 to 65.234.255.25465.234.255.25532,766
8765.235.0.0/1765.235.0.1 to 65.235.127.25465.235.127.25532,766
8865.235.128.0/1765.235.128.1 to 65.235.255.25465.235.255.25532,766
8965.236.0.0/1765.236.0.1 to 65.236.127.25465.236.127.25532,766
9065.236.128.0/1765.236.128.1 to 65.236.255.25465.236.255.25532,766
9165.237.0.0/1765.237.0.1 to 65.237.127.25465.237.127.25532,766
9265.237.128.0/1765.237.128.1 to 65.237.255.25465.237.255.25532,766
9365.238.0.0/1765.238.0.1 to 65.238.127.25465.238.127.25532,766
9465.238.128.0/1765.238.128.1 to 65.238.255.25465.238.255.25532,766
9565.239.0.0/1765.239.0.1 to 65.239.127.25465.239.127.25532,766
9665.239.128.0/1765.239.128.1 to 65.239.255.25465.239.255.25532,766
9765.240.0.0/1765.240.0.1 to 65.240.127.25465.240.127.25532,766
9865.240.128.0/1765.240.128.1 to 65.240.255.25465.240.255.25532,766
9965.241.0.0/1765.241.0.1 to 65.241.127.25465.241.127.25532,766
10065.241.128.0/1765.241.128.1 to 65.241.255.25465.241.255.25532,766
10165.242.0.0/1765.242.0.1 to 65.242.127.25465.242.127.25532,766
10265.242.128.0/1765.242.128.1 to 65.242.255.25465.242.255.25532,766
10365.243.0.0/1765.243.0.1 to 65.243.127.25465.243.127.25532,766
10465.243.128.0/1765.243.128.1 to 65.243.255.25465.243.255.25532,766
10565.244.0.0/1765.244.0.1 to 65.244.127.25465.244.127.25532,766
10665.244.128.0/1765.244.128.1 to 65.244.255.25465.244.255.25532,766
10765.245.0.0/1765.245.0.1 to 65.245.127.25465.245.127.25532,766
10865.245.128.0/1765.245.128.1 to 65.245.255.25465.245.255.25532,766
10965.246.0.0/1765.246.0.1 to 65.246.127.25465.246.127.25532,766
11065.246.128.0/1765.246.128.1 to 65.246.255.25465.246.255.25532,766
11165.247.0.0/1765.247.0.1 to 65.247.127.25465.247.127.25532,766
11265.247.128.0/1765.247.128.1 to 65.247.255.25465.247.255.25532,766
11365.248.0.0/1765.248.0.1 to 65.248.127.25465.248.127.25532,766
11465.248.128.0/1765.248.128.1 to 65.248.255.25465.248.255.25532,766
11565.249.0.0/1765.249.0.1 to 65.249.127.25465.249.127.25532,766
11665.249.128.0/1765.249.128.1 to 65.249.255.25465.249.255.25532,766
11765.250.0.0/1765.250.0.1 to 65.250.127.25465.250.127.25532,766
11865.250.128.0/1765.250.128.1 to 65.250.255.25465.250.255.25532,766
11965.251.0.0/1765.251.0.1 to 65.251.127.25465.251.127.25532,766
12065.251.128.0/1765.251.128.1 to 65.251.255.25465.251.255.25532,766
12165.252.0.0/1765.252.0.1 to 65.252.127.25465.252.127.25532,766
12265.252.128.0/1765.252.128.1 to 65.252.255.25465.252.255.25532,766
12365.253.0.0/1765.253.0.1 to 65.253.127.25465.253.127.25532,766
12465.253.128.0/1765.253.128.1 to 65.253.255.25465.253.255.25532,766
12565.254.0.0/1765.254.0.1 to 65.254.127.25465.254.127.25532,766
12665.254.128.0/1765.254.128.1 to 65.254.255.25465.254.255.25532,766
12765.255.0.0/1765.255.0.1 to 65.255.127.25465.255.127.25532,766
12865.255.128.0/1765.255.128.1 to 65.255.255.25465.255.255.25532,766

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.