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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.

Network246.96.0.0/13
Usable hosts524,286
Subnet mask255.248.0.0
Addresses524,288
Network address
246.96.0.0
Broadcast address
246.103.255.255
First usable
246.96.0.1
Last usable
246.103.255.254
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
Reserved 240.0.0.0/4
Future use; not usable on most systems
Old class
E (reserved)
As numbers
Hex F6600000 · Integer 4133486592 to 4134010879
Reverse DNS zones
96.246.in-addr.arpa
97.246.in-addr.arpa
98.246.in-addr.arpa
99.246.in-addr.arpa
100.246.in-addr.arpa
101.246.in-addr.arpa
102.246.in-addr.arpa
103.246.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
Address11110110.01100000.00000000.00000000246.96.0.0
Subnet mask11111111.11111000.00000000.00000000255.248.0.0
Network11110110.01100000.00000000.00000000246.96.0.0
Broadcast11110110.01100111.11111111.11111111246.103.255.255
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)

246.96.0.0/13 makes 64 subnets of /19.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1246.96.0.0/19246.96.0.1 to 246.96.31.254246.96.31.2558,190
2246.96.32.0/19246.96.32.1 to 246.96.63.254246.96.63.2558,190
3246.96.64.0/19246.96.64.1 to 246.96.95.254246.96.95.2558,190
4246.96.96.0/19246.96.96.1 to 246.96.127.254246.96.127.2558,190
5246.96.128.0/19246.96.128.1 to 246.96.159.254246.96.159.2558,190
6246.96.160.0/19246.96.160.1 to 246.96.191.254246.96.191.2558,190
7246.96.192.0/19246.96.192.1 to 246.96.223.254246.96.223.2558,190
8246.96.224.0/19246.96.224.1 to 246.96.255.254246.96.255.2558,190
9246.97.0.0/19246.97.0.1 to 246.97.31.254246.97.31.2558,190
10246.97.32.0/19246.97.32.1 to 246.97.63.254246.97.63.2558,190
11246.97.64.0/19246.97.64.1 to 246.97.95.254246.97.95.2558,190
12246.97.96.0/19246.97.96.1 to 246.97.127.254246.97.127.2558,190
13246.97.128.0/19246.97.128.1 to 246.97.159.254246.97.159.2558,190
14246.97.160.0/19246.97.160.1 to 246.97.191.254246.97.191.2558,190
15246.97.192.0/19246.97.192.1 to 246.97.223.254246.97.223.2558,190
16246.97.224.0/19246.97.224.1 to 246.97.255.254246.97.255.2558,190
17246.98.0.0/19246.98.0.1 to 246.98.31.254246.98.31.2558,190
18246.98.32.0/19246.98.32.1 to 246.98.63.254246.98.63.2558,190
19246.98.64.0/19246.98.64.1 to 246.98.95.254246.98.95.2558,190
20246.98.96.0/19246.98.96.1 to 246.98.127.254246.98.127.2558,190
21246.98.128.0/19246.98.128.1 to 246.98.159.254246.98.159.2558,190
22246.98.160.0/19246.98.160.1 to 246.98.191.254246.98.191.2558,190
23246.98.192.0/19246.98.192.1 to 246.98.223.254246.98.223.2558,190
24246.98.224.0/19246.98.224.1 to 246.98.255.254246.98.255.2558,190
25246.99.0.0/19246.99.0.1 to 246.99.31.254246.99.31.2558,190
26246.99.32.0/19246.99.32.1 to 246.99.63.254246.99.63.2558,190
27246.99.64.0/19246.99.64.1 to 246.99.95.254246.99.95.2558,190
28246.99.96.0/19246.99.96.1 to 246.99.127.254246.99.127.2558,190
29246.99.128.0/19246.99.128.1 to 246.99.159.254246.99.159.2558,190
30246.99.160.0/19246.99.160.1 to 246.99.191.254246.99.191.2558,190
31246.99.192.0/19246.99.192.1 to 246.99.223.254246.99.223.2558,190
32246.99.224.0/19246.99.224.1 to 246.99.255.254246.99.255.2558,190
33246.100.0.0/19246.100.0.1 to 246.100.31.254246.100.31.2558,190
34246.100.32.0/19246.100.32.1 to 246.100.63.254246.100.63.2558,190
35246.100.64.0/19246.100.64.1 to 246.100.95.254246.100.95.2558,190
36246.100.96.0/19246.100.96.1 to 246.100.127.254246.100.127.2558,190
37246.100.128.0/19246.100.128.1 to 246.100.159.254246.100.159.2558,190
38246.100.160.0/19246.100.160.1 to 246.100.191.254246.100.191.2558,190
39246.100.192.0/19246.100.192.1 to 246.100.223.254246.100.223.2558,190
40246.100.224.0/19246.100.224.1 to 246.100.255.254246.100.255.2558,190
41246.101.0.0/19246.101.0.1 to 246.101.31.254246.101.31.2558,190
42246.101.32.0/19246.101.32.1 to 246.101.63.254246.101.63.2558,190
43246.101.64.0/19246.101.64.1 to 246.101.95.254246.101.95.2558,190
44246.101.96.0/19246.101.96.1 to 246.101.127.254246.101.127.2558,190
45246.101.128.0/19246.101.128.1 to 246.101.159.254246.101.159.2558,190
46246.101.160.0/19246.101.160.1 to 246.101.191.254246.101.191.2558,190
47246.101.192.0/19246.101.192.1 to 246.101.223.254246.101.223.2558,190
48246.101.224.0/19246.101.224.1 to 246.101.255.254246.101.255.2558,190
49246.102.0.0/19246.102.0.1 to 246.102.31.254246.102.31.2558,190
50246.102.32.0/19246.102.32.1 to 246.102.63.254246.102.63.2558,190
51246.102.64.0/19246.102.64.1 to 246.102.95.254246.102.95.2558,190
52246.102.96.0/19246.102.96.1 to 246.102.127.254246.102.127.2558,190
53246.102.128.0/19246.102.128.1 to 246.102.159.254246.102.159.2558,190
54246.102.160.0/19246.102.160.1 to 246.102.191.254246.102.191.2558,190
55246.102.192.0/19246.102.192.1 to 246.102.223.254246.102.223.2558,190
56246.102.224.0/19246.102.224.1 to 246.102.255.254246.102.255.2558,190
57246.103.0.0/19246.103.0.1 to 246.103.31.254246.103.31.2558,190
58246.103.32.0/19246.103.32.1 to 246.103.63.254246.103.63.2558,190
59246.103.64.0/19246.103.64.1 to 246.103.95.254246.103.95.2558,190
60246.103.96.0/19246.103.96.1 to 246.103.127.254246.103.127.2558,190
61246.103.128.0/19246.103.128.1 to 246.103.159.254246.103.159.2558,190
62246.103.160.0/19246.103.160.1 to 246.103.191.254246.103.191.2558,190
63246.103.192.0/19246.103.192.1 to 246.103.223.254246.103.223.2558,190
64246.103.224.0/19246.103.224.1 to 246.103.255.254246.103.255.2558,190

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.