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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.

Network96.0.0.0/3
Usable hosts536,870,910
Subnet mask224.0.0.0
Addresses536,870,912
Network address
96.0.0.0
Broadcast address
127.255.255.255
First usable
96.0.0.1
Last usable
127.255.255.254
Usable hosts
536,870,910 (536,870,912 less the network and broadcast addresses)
Subnet mask
224.0.0.0
Wildcard mask
31.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/3
Type
Public public
Old class
A (default /8)
As numbers
Hex 60000000 · Integer 1610612736 to 2147483647
Reverse DNS zones
96.in-addr.arpa
97.in-addr.arpa
98.in-addr.arpa
99.in-addr.arpa
100.in-addr.arpa
101.in-addr.arpa
102.in-addr.arpa
103.in-addr.arpa
104.in-addr.arpa
105.in-addr.arpa
106.in-addr.arpa
107.in-addr.arpa
108.in-addr.arpa
109.in-addr.arpa
110.in-addr.arpa
111.in-addr.arpa
and 16 more
/3 is not on a 8-bit boundary, so it takes 32 /8 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01100000.00000000.00000000.0000000096.0.0.0
Subnet mask11100000.00000000.00000000.00000000224.0.0.0
Network01100000.00000000.00000000.0000000096.0.0.0
Broadcast01111111.11111111.11111111.11111111127.255.255.255
Split into smaller subnets/9
/4 (2)/5 (4)/6 (8)/7 (16)/8 (32)/9 (64)/10 (128)/11 (256)/12 (512)/13 (1,024)/14 (2,048)/15 (4,096)

96.0.0.0/3 makes 64 subnets of /9.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
196.0.0.0/996.0.0.1 to 96.127.255.25496.127.255.2558,388,606
296.128.0.0/996.128.0.1 to 96.255.255.25496.255.255.2558,388,606
397.0.0.0/997.0.0.1 to 97.127.255.25497.127.255.2558,388,606
497.128.0.0/997.128.0.1 to 97.255.255.25497.255.255.2558,388,606
598.0.0.0/998.0.0.1 to 98.127.255.25498.127.255.2558,388,606
698.128.0.0/998.128.0.1 to 98.255.255.25498.255.255.2558,388,606
799.0.0.0/999.0.0.1 to 99.127.255.25499.127.255.2558,388,606
899.128.0.0/999.128.0.1 to 99.255.255.25499.255.255.2558,388,606
9100.0.0.0/9100.0.0.1 to 100.127.255.254100.127.255.2558,388,606
10100.128.0.0/9100.128.0.1 to 100.255.255.254100.255.255.2558,388,606
11101.0.0.0/9101.0.0.1 to 101.127.255.254101.127.255.2558,388,606
12101.128.0.0/9101.128.0.1 to 101.255.255.254101.255.255.2558,388,606
13102.0.0.0/9102.0.0.1 to 102.127.255.254102.127.255.2558,388,606
14102.128.0.0/9102.128.0.1 to 102.255.255.254102.255.255.2558,388,606
15103.0.0.0/9103.0.0.1 to 103.127.255.254103.127.255.2558,388,606
16103.128.0.0/9103.128.0.1 to 103.255.255.254103.255.255.2558,388,606
17104.0.0.0/9104.0.0.1 to 104.127.255.254104.127.255.2558,388,606
18104.128.0.0/9104.128.0.1 to 104.255.255.254104.255.255.2558,388,606
19105.0.0.0/9105.0.0.1 to 105.127.255.254105.127.255.2558,388,606
20105.128.0.0/9105.128.0.1 to 105.255.255.254105.255.255.2558,388,606
21106.0.0.0/9106.0.0.1 to 106.127.255.254106.127.255.2558,388,606
22106.128.0.0/9106.128.0.1 to 106.255.255.254106.255.255.2558,388,606
23107.0.0.0/9107.0.0.1 to 107.127.255.254107.127.255.2558,388,606
24107.128.0.0/9107.128.0.1 to 107.255.255.254107.255.255.2558,388,606
25108.0.0.0/9108.0.0.1 to 108.127.255.254108.127.255.2558,388,606
26108.128.0.0/9108.128.0.1 to 108.255.255.254108.255.255.2558,388,606
27109.0.0.0/9109.0.0.1 to 109.127.255.254109.127.255.2558,388,606
28109.128.0.0/9109.128.0.1 to 109.255.255.254109.255.255.2558,388,606
29110.0.0.0/9110.0.0.1 to 110.127.255.254110.127.255.2558,388,606
30110.128.0.0/9110.128.0.1 to 110.255.255.254110.255.255.2558,388,606
31111.0.0.0/9111.0.0.1 to 111.127.255.254111.127.255.2558,388,606
32111.128.0.0/9111.128.0.1 to 111.255.255.254111.255.255.2558,388,606
33112.0.0.0/9112.0.0.1 to 112.127.255.254112.127.255.2558,388,606
34112.128.0.0/9112.128.0.1 to 112.255.255.254112.255.255.2558,388,606
35113.0.0.0/9113.0.0.1 to 113.127.255.254113.127.255.2558,388,606
36113.128.0.0/9113.128.0.1 to 113.255.255.254113.255.255.2558,388,606
37114.0.0.0/9114.0.0.1 to 114.127.255.254114.127.255.2558,388,606
38114.128.0.0/9114.128.0.1 to 114.255.255.254114.255.255.2558,388,606
39115.0.0.0/9115.0.0.1 to 115.127.255.254115.127.255.2558,388,606
40115.128.0.0/9115.128.0.1 to 115.255.255.254115.255.255.2558,388,606
41116.0.0.0/9116.0.0.1 to 116.127.255.254116.127.255.2558,388,606
42116.128.0.0/9116.128.0.1 to 116.255.255.254116.255.255.2558,388,606
43117.0.0.0/9117.0.0.1 to 117.127.255.254117.127.255.2558,388,606
44117.128.0.0/9117.128.0.1 to 117.255.255.254117.255.255.2558,388,606
45118.0.0.0/9118.0.0.1 to 118.127.255.254118.127.255.2558,388,606
46118.128.0.0/9118.128.0.1 to 118.255.255.254118.255.255.2558,388,606
47119.0.0.0/9119.0.0.1 to 119.127.255.254119.127.255.2558,388,606
48119.128.0.0/9119.128.0.1 to 119.255.255.254119.255.255.2558,388,606
49120.0.0.0/9120.0.0.1 to 120.127.255.254120.127.255.2558,388,606
50120.128.0.0/9120.128.0.1 to 120.255.255.254120.255.255.2558,388,606
51121.0.0.0/9121.0.0.1 to 121.127.255.254121.127.255.2558,388,606
52121.128.0.0/9121.128.0.1 to 121.255.255.254121.255.255.2558,388,606
53122.0.0.0/9122.0.0.1 to 122.127.255.254122.127.255.2558,388,606
54122.128.0.0/9122.128.0.1 to 122.255.255.254122.255.255.2558,388,606
55123.0.0.0/9123.0.0.1 to 123.127.255.254123.127.255.2558,388,606
56123.128.0.0/9123.128.0.1 to 123.255.255.254123.255.255.2558,388,606
57124.0.0.0/9124.0.0.1 to 124.127.255.254124.127.255.2558,388,606
58124.128.0.0/9124.128.0.1 to 124.255.255.254124.255.255.2558,388,606
59125.0.0.0/9125.0.0.1 to 125.127.255.254125.127.255.2558,388,606
60125.128.0.0/9125.128.0.1 to 125.255.255.254125.255.255.2558,388,606
61126.0.0.0/9126.0.0.1 to 126.127.255.254126.127.255.2558,388,606
62126.128.0.0/9126.128.0.1 to 126.255.255.254126.255.255.2558,388,606
63127.0.0.0/9127.0.0.1 to 127.127.255.254127.127.255.2558,388,606
64127.128.0.0/9127.128.0.1 to 127.255.255.254127.255.255.2558,388,606

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.