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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.

Network197.232.0.0/13
Usable hosts524,286
Subnet mask255.248.0.0
Addresses524,288
Network address
197.232.0.0
Broadcast address
197.239.255.255
First usable
197.232.0.1
Last usable
197.239.255.254
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
C (default /24)
As numbers
Hex C5E80000 · Integer 3320315904 to 3320840191
Reverse DNS zones
232.197.in-addr.arpa
233.197.in-addr.arpa
234.197.in-addr.arpa
235.197.in-addr.arpa
236.197.in-addr.arpa
237.197.in-addr.arpa
238.197.in-addr.arpa
239.197.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
Address11000101.11101000.00000000.00000000197.232.0.0
Subnet mask11111111.11111000.00000000.00000000255.248.0.0
Network11000101.11101000.00000000.00000000197.232.0.0
Broadcast11000101.11101111.11111111.11111111197.239.255.255
Split into smaller subnets/19
/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)

197.232.0.0/13 makes 64 subnets of /19.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1197.232.0.0/19197.232.0.1 to 197.232.31.254197.232.31.2558,190
2197.232.32.0/19197.232.32.1 to 197.232.63.254197.232.63.2558,190
3197.232.64.0/19197.232.64.1 to 197.232.95.254197.232.95.2558,190
4197.232.96.0/19197.232.96.1 to 197.232.127.254197.232.127.2558,190
5197.232.128.0/19197.232.128.1 to 197.232.159.254197.232.159.2558,190
6197.232.160.0/19197.232.160.1 to 197.232.191.254197.232.191.2558,190
7197.232.192.0/19197.232.192.1 to 197.232.223.254197.232.223.2558,190
8197.232.224.0/19197.232.224.1 to 197.232.255.254197.232.255.2558,190
9197.233.0.0/19197.233.0.1 to 197.233.31.254197.233.31.2558,190
10197.233.32.0/19197.233.32.1 to 197.233.63.254197.233.63.2558,190
11197.233.64.0/19197.233.64.1 to 197.233.95.254197.233.95.2558,190
12197.233.96.0/19197.233.96.1 to 197.233.127.254197.233.127.2558,190
13197.233.128.0/19197.233.128.1 to 197.233.159.254197.233.159.2558,190
14197.233.160.0/19197.233.160.1 to 197.233.191.254197.233.191.2558,190
15197.233.192.0/19197.233.192.1 to 197.233.223.254197.233.223.2558,190
16197.233.224.0/19197.233.224.1 to 197.233.255.254197.233.255.2558,190
17197.234.0.0/19197.234.0.1 to 197.234.31.254197.234.31.2558,190
18197.234.32.0/19197.234.32.1 to 197.234.63.254197.234.63.2558,190
19197.234.64.0/19197.234.64.1 to 197.234.95.254197.234.95.2558,190
20197.234.96.0/19197.234.96.1 to 197.234.127.254197.234.127.2558,190
21197.234.128.0/19197.234.128.1 to 197.234.159.254197.234.159.2558,190
22197.234.160.0/19197.234.160.1 to 197.234.191.254197.234.191.2558,190
23197.234.192.0/19197.234.192.1 to 197.234.223.254197.234.223.2558,190
24197.234.224.0/19197.234.224.1 to 197.234.255.254197.234.255.2558,190
25197.235.0.0/19197.235.0.1 to 197.235.31.254197.235.31.2558,190
26197.235.32.0/19197.235.32.1 to 197.235.63.254197.235.63.2558,190
27197.235.64.0/19197.235.64.1 to 197.235.95.254197.235.95.2558,190
28197.235.96.0/19197.235.96.1 to 197.235.127.254197.235.127.2558,190
29197.235.128.0/19197.235.128.1 to 197.235.159.254197.235.159.2558,190
30197.235.160.0/19197.235.160.1 to 197.235.191.254197.235.191.2558,190
31197.235.192.0/19197.235.192.1 to 197.235.223.254197.235.223.2558,190
32197.235.224.0/19197.235.224.1 to 197.235.255.254197.235.255.2558,190
33197.236.0.0/19197.236.0.1 to 197.236.31.254197.236.31.2558,190
34197.236.32.0/19197.236.32.1 to 197.236.63.254197.236.63.2558,190
35197.236.64.0/19197.236.64.1 to 197.236.95.254197.236.95.2558,190
36197.236.96.0/19197.236.96.1 to 197.236.127.254197.236.127.2558,190
37197.236.128.0/19197.236.128.1 to 197.236.159.254197.236.159.2558,190
38197.236.160.0/19197.236.160.1 to 197.236.191.254197.236.191.2558,190
39197.236.192.0/19197.236.192.1 to 197.236.223.254197.236.223.2558,190
40197.236.224.0/19197.236.224.1 to 197.236.255.254197.236.255.2558,190
41197.237.0.0/19197.237.0.1 to 197.237.31.254197.237.31.2558,190
42197.237.32.0/19197.237.32.1 to 197.237.63.254197.237.63.2558,190
43197.237.64.0/19197.237.64.1 to 197.237.95.254197.237.95.2558,190
44197.237.96.0/19197.237.96.1 to 197.237.127.254197.237.127.2558,190
45197.237.128.0/19197.237.128.1 to 197.237.159.254197.237.159.2558,190
46197.237.160.0/19197.237.160.1 to 197.237.191.254197.237.191.2558,190
47197.237.192.0/19197.237.192.1 to 197.237.223.254197.237.223.2558,190
48197.237.224.0/19197.237.224.1 to 197.237.255.254197.237.255.2558,190
49197.238.0.0/19197.238.0.1 to 197.238.31.254197.238.31.2558,190
50197.238.32.0/19197.238.32.1 to 197.238.63.254197.238.63.2558,190
51197.238.64.0/19197.238.64.1 to 197.238.95.254197.238.95.2558,190
52197.238.96.0/19197.238.96.1 to 197.238.127.254197.238.127.2558,190
53197.238.128.0/19197.238.128.1 to 197.238.159.254197.238.159.2558,190
54197.238.160.0/19197.238.160.1 to 197.238.191.254197.238.191.2558,190
55197.238.192.0/19197.238.192.1 to 197.238.223.254197.238.223.2558,190
56197.238.224.0/19197.238.224.1 to 197.238.255.254197.238.255.2558,190
57197.239.0.0/19197.239.0.1 to 197.239.31.254197.239.31.2558,190
58197.239.32.0/19197.239.32.1 to 197.239.63.254197.239.63.2558,190
59197.239.64.0/19197.239.64.1 to 197.239.95.254197.239.95.2558,190
60197.239.96.0/19197.239.96.1 to 197.239.127.254197.239.127.2558,190
61197.239.128.0/19197.239.128.1 to 197.239.159.254197.239.159.2558,190
62197.239.160.0/19197.239.160.1 to 197.239.191.254197.239.191.2558,190
63197.239.192.0/19197.239.192.1 to 197.239.223.254197.239.223.2558,190
64197.239.224.0/19197.239.224.1 to 197.239.255.254197.239.255.2558,190

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.