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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.

Network24.65.232.0/23
Usable hosts510
Subnet mask255.255.254.0
Addresses512
Network address
24.65.232.0
Broadcast address
24.65.233.255
First usable
24.65.232.1
Last usable
24.65.233.254
Usable hosts
510 (512 less the network and broadcast addresses)
Subnet mask
255.255.254.0
Wildcard mask
0.0.1.255 (Cisco ACLs, OSPF)
Prefix length
/23
Type
Public public
Old class
A (default /8)
As numbers
Hex 1841E800 · Integer 406972416 to 406972927
Reverse DNS zones
232.65.24.in-addr.arpa
233.65.24.in-addr.arpa
/23 is not on a 8-bit boundary, so it takes 2 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00011000.01000001.11101000.0000000024.65.232.0
Subnet mask11111111.11111111.11111110.00000000255.255.254.0
Network00011000.01000001.11101000.0000000024.65.232.0
Broadcast00011000.01000001.11101001.1111111124.65.233.255
Split into smaller subnets/30
/24 (2)/25 (4)/26 (8)/27 (16)/28 (32)/29 (64)/30 (128)/31 (256)/32 (512)

24.65.232.0/23 makes 128 subnets of /30.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
124.65.232.0/3024.65.232.1 to 24.65.232.224.65.232.32
224.65.232.4/3024.65.232.5 to 24.65.232.624.65.232.72
324.65.232.8/3024.65.232.9 to 24.65.232.1024.65.232.112
424.65.232.12/3024.65.232.13 to 24.65.232.1424.65.232.152
524.65.232.16/3024.65.232.17 to 24.65.232.1824.65.232.192
624.65.232.20/3024.65.232.21 to 24.65.232.2224.65.232.232
724.65.232.24/3024.65.232.25 to 24.65.232.2624.65.232.272
824.65.232.28/3024.65.232.29 to 24.65.232.3024.65.232.312
924.65.232.32/3024.65.232.33 to 24.65.232.3424.65.232.352
1024.65.232.36/3024.65.232.37 to 24.65.232.3824.65.232.392
1124.65.232.40/3024.65.232.41 to 24.65.232.4224.65.232.432
1224.65.232.44/3024.65.232.45 to 24.65.232.4624.65.232.472
1324.65.232.48/3024.65.232.49 to 24.65.232.5024.65.232.512
1424.65.232.52/3024.65.232.53 to 24.65.232.5424.65.232.552
1524.65.232.56/3024.65.232.57 to 24.65.232.5824.65.232.592
1624.65.232.60/3024.65.232.61 to 24.65.232.6224.65.232.632
1724.65.232.64/3024.65.232.65 to 24.65.232.6624.65.232.672
1824.65.232.68/3024.65.232.69 to 24.65.232.7024.65.232.712
1924.65.232.72/3024.65.232.73 to 24.65.232.7424.65.232.752
2024.65.232.76/3024.65.232.77 to 24.65.232.7824.65.232.792
2124.65.232.80/3024.65.232.81 to 24.65.232.8224.65.232.832
2224.65.232.84/3024.65.232.85 to 24.65.232.8624.65.232.872
2324.65.232.88/3024.65.232.89 to 24.65.232.9024.65.232.912
2424.65.232.92/3024.65.232.93 to 24.65.232.9424.65.232.952
2524.65.232.96/3024.65.232.97 to 24.65.232.9824.65.232.992
2624.65.232.100/3024.65.232.101 to 24.65.232.10224.65.232.1032
2724.65.232.104/3024.65.232.105 to 24.65.232.10624.65.232.1072
2824.65.232.108/3024.65.232.109 to 24.65.232.11024.65.232.1112
2924.65.232.112/3024.65.232.113 to 24.65.232.11424.65.232.1152
3024.65.232.116/3024.65.232.117 to 24.65.232.11824.65.232.1192
3124.65.232.120/3024.65.232.121 to 24.65.232.12224.65.232.1232
3224.65.232.124/3024.65.232.125 to 24.65.232.12624.65.232.1272
3324.65.232.128/3024.65.232.129 to 24.65.232.13024.65.232.1312
3424.65.232.132/3024.65.232.133 to 24.65.232.13424.65.232.1352
3524.65.232.136/3024.65.232.137 to 24.65.232.13824.65.232.1392
3624.65.232.140/3024.65.232.141 to 24.65.232.14224.65.232.1432
3724.65.232.144/3024.65.232.145 to 24.65.232.14624.65.232.1472
3824.65.232.148/3024.65.232.149 to 24.65.232.15024.65.232.1512
3924.65.232.152/3024.65.232.153 to 24.65.232.15424.65.232.1552
4024.65.232.156/3024.65.232.157 to 24.65.232.15824.65.232.1592
4124.65.232.160/3024.65.232.161 to 24.65.232.16224.65.232.1632
4224.65.232.164/3024.65.232.165 to 24.65.232.16624.65.232.1672
4324.65.232.168/3024.65.232.169 to 24.65.232.17024.65.232.1712
4424.65.232.172/3024.65.232.173 to 24.65.232.17424.65.232.1752
4524.65.232.176/3024.65.232.177 to 24.65.232.17824.65.232.1792
4624.65.232.180/3024.65.232.181 to 24.65.232.18224.65.232.1832
4724.65.232.184/3024.65.232.185 to 24.65.232.18624.65.232.1872
4824.65.232.188/3024.65.232.189 to 24.65.232.19024.65.232.1912
4924.65.232.192/3024.65.232.193 to 24.65.232.19424.65.232.1952
5024.65.232.196/3024.65.232.197 to 24.65.232.19824.65.232.1992
5124.65.232.200/3024.65.232.201 to 24.65.232.20224.65.232.2032
5224.65.232.204/3024.65.232.205 to 24.65.232.20624.65.232.2072
5324.65.232.208/3024.65.232.209 to 24.65.232.21024.65.232.2112
5424.65.232.212/3024.65.232.213 to 24.65.232.21424.65.232.2152
5524.65.232.216/3024.65.232.217 to 24.65.232.21824.65.232.2192
5624.65.232.220/3024.65.232.221 to 24.65.232.22224.65.232.2232
5724.65.232.224/3024.65.232.225 to 24.65.232.22624.65.232.2272
5824.65.232.228/3024.65.232.229 to 24.65.232.23024.65.232.2312
5924.65.232.232/3024.65.232.233 to 24.65.232.23424.65.232.2352
6024.65.232.236/3024.65.232.237 to 24.65.232.23824.65.232.2392
6124.65.232.240/3024.65.232.241 to 24.65.232.24224.65.232.2432
6224.65.232.244/3024.65.232.245 to 24.65.232.24624.65.232.2472
6324.65.232.248/3024.65.232.249 to 24.65.232.25024.65.232.2512
6424.65.232.252/3024.65.232.253 to 24.65.232.25424.65.232.2552
6524.65.233.0/3024.65.233.1 to 24.65.233.224.65.233.32
6624.65.233.4/3024.65.233.5 to 24.65.233.624.65.233.72
6724.65.233.8/3024.65.233.9 to 24.65.233.1024.65.233.112
6824.65.233.12/3024.65.233.13 to 24.65.233.1424.65.233.152
6924.65.233.16/3024.65.233.17 to 24.65.233.1824.65.233.192
7024.65.233.20/3024.65.233.21 to 24.65.233.2224.65.233.232
7124.65.233.24/3024.65.233.25 to 24.65.233.2624.65.233.272
7224.65.233.28/3024.65.233.29 to 24.65.233.3024.65.233.312
7324.65.233.32/3024.65.233.33 to 24.65.233.3424.65.233.352
7424.65.233.36/3024.65.233.37 to 24.65.233.3824.65.233.392
7524.65.233.40/3024.65.233.41 to 24.65.233.4224.65.233.432
7624.65.233.44/3024.65.233.45 to 24.65.233.4624.65.233.472
7724.65.233.48/3024.65.233.49 to 24.65.233.5024.65.233.512
7824.65.233.52/3024.65.233.53 to 24.65.233.5424.65.233.552
7924.65.233.56/3024.65.233.57 to 24.65.233.5824.65.233.592
8024.65.233.60/3024.65.233.61 to 24.65.233.6224.65.233.632
8124.65.233.64/3024.65.233.65 to 24.65.233.6624.65.233.672
8224.65.233.68/3024.65.233.69 to 24.65.233.7024.65.233.712
8324.65.233.72/3024.65.233.73 to 24.65.233.7424.65.233.752
8424.65.233.76/3024.65.233.77 to 24.65.233.7824.65.233.792
8524.65.233.80/3024.65.233.81 to 24.65.233.8224.65.233.832
8624.65.233.84/3024.65.233.85 to 24.65.233.8624.65.233.872
8724.65.233.88/3024.65.233.89 to 24.65.233.9024.65.233.912
8824.65.233.92/3024.65.233.93 to 24.65.233.9424.65.233.952
8924.65.233.96/3024.65.233.97 to 24.65.233.9824.65.233.992
9024.65.233.100/3024.65.233.101 to 24.65.233.10224.65.233.1032
9124.65.233.104/3024.65.233.105 to 24.65.233.10624.65.233.1072
9224.65.233.108/3024.65.233.109 to 24.65.233.11024.65.233.1112
9324.65.233.112/3024.65.233.113 to 24.65.233.11424.65.233.1152
9424.65.233.116/3024.65.233.117 to 24.65.233.11824.65.233.1192
9524.65.233.120/3024.65.233.121 to 24.65.233.12224.65.233.1232
9624.65.233.124/3024.65.233.125 to 24.65.233.12624.65.233.1272
9724.65.233.128/3024.65.233.129 to 24.65.233.13024.65.233.1312
9824.65.233.132/3024.65.233.133 to 24.65.233.13424.65.233.1352
9924.65.233.136/3024.65.233.137 to 24.65.233.13824.65.233.1392
10024.65.233.140/3024.65.233.141 to 24.65.233.14224.65.233.1432
10124.65.233.144/3024.65.233.145 to 24.65.233.14624.65.233.1472
10224.65.233.148/3024.65.233.149 to 24.65.233.15024.65.233.1512
10324.65.233.152/3024.65.233.153 to 24.65.233.15424.65.233.1552
10424.65.233.156/3024.65.233.157 to 24.65.233.15824.65.233.1592
10524.65.233.160/3024.65.233.161 to 24.65.233.16224.65.233.1632
10624.65.233.164/3024.65.233.165 to 24.65.233.16624.65.233.1672
10724.65.233.168/3024.65.233.169 to 24.65.233.17024.65.233.1712
10824.65.233.172/3024.65.233.173 to 24.65.233.17424.65.233.1752
10924.65.233.176/3024.65.233.177 to 24.65.233.17824.65.233.1792
11024.65.233.180/3024.65.233.181 to 24.65.233.18224.65.233.1832
11124.65.233.184/3024.65.233.185 to 24.65.233.18624.65.233.1872
11224.65.233.188/3024.65.233.189 to 24.65.233.19024.65.233.1912
11324.65.233.192/3024.65.233.193 to 24.65.233.19424.65.233.1952
11424.65.233.196/3024.65.233.197 to 24.65.233.19824.65.233.1992
11524.65.233.200/3024.65.233.201 to 24.65.233.20224.65.233.2032
11624.65.233.204/3024.65.233.205 to 24.65.233.20624.65.233.2072
11724.65.233.208/3024.65.233.209 to 24.65.233.21024.65.233.2112
11824.65.233.212/3024.65.233.213 to 24.65.233.21424.65.233.2152
11924.65.233.216/3024.65.233.217 to 24.65.233.21824.65.233.2192
12024.65.233.220/3024.65.233.221 to 24.65.233.22224.65.233.2232
12124.65.233.224/3024.65.233.225 to 24.65.233.22624.65.233.2272
12224.65.233.228/3024.65.233.229 to 24.65.233.23024.65.233.2312
12324.65.233.232/3024.65.233.233 to 24.65.233.23424.65.233.2352
12424.65.233.236/3024.65.233.237 to 24.65.233.23824.65.233.2392
12524.65.233.240/3024.65.233.241 to 24.65.233.24224.65.233.2432
12624.65.233.244/3024.65.233.245 to 24.65.233.24624.65.233.2472
12724.65.233.248/3024.65.233.249 to 24.65.233.25024.65.233.2512
12824.65.233.252/3024.65.233.253 to 24.65.233.25424.65.233.2552

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.