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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.

Network234.128.0.0/10
Usable hosts4,194,302
Subnet mask255.192.0.0
Addresses4,194,304
Network address
234.128.0.0
Broadcast address
234.191.255.255
First usable
234.128.0.1
Last usable
234.191.255.254
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
Multicast 224.0.0.0/4
One-to-many traffic, such as IPTV and routing protocols
Old class
D (multicast)
As numbers
Hex EA800000 · Integer 3934257152 to 3938451455
Reverse DNS zones
128.234.in-addr.arpa
129.234.in-addr.arpa
130.234.in-addr.arpa
131.234.in-addr.arpa
132.234.in-addr.arpa
133.234.in-addr.arpa
134.234.in-addr.arpa
135.234.in-addr.arpa
136.234.in-addr.arpa
137.234.in-addr.arpa
138.234.in-addr.arpa
139.234.in-addr.arpa
140.234.in-addr.arpa
141.234.in-addr.arpa
142.234.in-addr.arpa
143.234.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
Address11101010.10000000.00000000.00000000234.128.0.0
Subnet mask11111111.11000000.00000000.00000000255.192.0.0
Network11101010.10000000.00000000.00000000234.128.0.0
Broadcast11101010.10111111.11111111.11111111234.191.255.255
Split into smaller subnets/16
/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)

234.128.0.0/10 makes 64 subnets of /16.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1234.128.0.0/16234.128.0.1 to 234.128.255.254234.128.255.25565,534
2234.129.0.0/16234.129.0.1 to 234.129.255.254234.129.255.25565,534
3234.130.0.0/16234.130.0.1 to 234.130.255.254234.130.255.25565,534
4234.131.0.0/16234.131.0.1 to 234.131.255.254234.131.255.25565,534
5234.132.0.0/16234.132.0.1 to 234.132.255.254234.132.255.25565,534
6234.133.0.0/16234.133.0.1 to 234.133.255.254234.133.255.25565,534
7234.134.0.0/16234.134.0.1 to 234.134.255.254234.134.255.25565,534
8234.135.0.0/16234.135.0.1 to 234.135.255.254234.135.255.25565,534
9234.136.0.0/16234.136.0.1 to 234.136.255.254234.136.255.25565,534
10234.137.0.0/16234.137.0.1 to 234.137.255.254234.137.255.25565,534
11234.138.0.0/16234.138.0.1 to 234.138.255.254234.138.255.25565,534
12234.139.0.0/16234.139.0.1 to 234.139.255.254234.139.255.25565,534
13234.140.0.0/16234.140.0.1 to 234.140.255.254234.140.255.25565,534
14234.141.0.0/16234.141.0.1 to 234.141.255.254234.141.255.25565,534
15234.142.0.0/16234.142.0.1 to 234.142.255.254234.142.255.25565,534
16234.143.0.0/16234.143.0.1 to 234.143.255.254234.143.255.25565,534
17234.144.0.0/16234.144.0.1 to 234.144.255.254234.144.255.25565,534
18234.145.0.0/16234.145.0.1 to 234.145.255.254234.145.255.25565,534
19234.146.0.0/16234.146.0.1 to 234.146.255.254234.146.255.25565,534
20234.147.0.0/16234.147.0.1 to 234.147.255.254234.147.255.25565,534
21234.148.0.0/16234.148.0.1 to 234.148.255.254234.148.255.25565,534
22234.149.0.0/16234.149.0.1 to 234.149.255.254234.149.255.25565,534
23234.150.0.0/16234.150.0.1 to 234.150.255.254234.150.255.25565,534
24234.151.0.0/16234.151.0.1 to 234.151.255.254234.151.255.25565,534
25234.152.0.0/16234.152.0.1 to 234.152.255.254234.152.255.25565,534
26234.153.0.0/16234.153.0.1 to 234.153.255.254234.153.255.25565,534
27234.154.0.0/16234.154.0.1 to 234.154.255.254234.154.255.25565,534
28234.155.0.0/16234.155.0.1 to 234.155.255.254234.155.255.25565,534
29234.156.0.0/16234.156.0.1 to 234.156.255.254234.156.255.25565,534
30234.157.0.0/16234.157.0.1 to 234.157.255.254234.157.255.25565,534
31234.158.0.0/16234.158.0.1 to 234.158.255.254234.158.255.25565,534
32234.159.0.0/16234.159.0.1 to 234.159.255.254234.159.255.25565,534
33234.160.0.0/16234.160.0.1 to 234.160.255.254234.160.255.25565,534
34234.161.0.0/16234.161.0.1 to 234.161.255.254234.161.255.25565,534
35234.162.0.0/16234.162.0.1 to 234.162.255.254234.162.255.25565,534
36234.163.0.0/16234.163.0.1 to 234.163.255.254234.163.255.25565,534
37234.164.0.0/16234.164.0.1 to 234.164.255.254234.164.255.25565,534
38234.165.0.0/16234.165.0.1 to 234.165.255.254234.165.255.25565,534
39234.166.0.0/16234.166.0.1 to 234.166.255.254234.166.255.25565,534
40234.167.0.0/16234.167.0.1 to 234.167.255.254234.167.255.25565,534
41234.168.0.0/16234.168.0.1 to 234.168.255.254234.168.255.25565,534
42234.169.0.0/16234.169.0.1 to 234.169.255.254234.169.255.25565,534
43234.170.0.0/16234.170.0.1 to 234.170.255.254234.170.255.25565,534
44234.171.0.0/16234.171.0.1 to 234.171.255.254234.171.255.25565,534
45234.172.0.0/16234.172.0.1 to 234.172.255.254234.172.255.25565,534
46234.173.0.0/16234.173.0.1 to 234.173.255.254234.173.255.25565,534
47234.174.0.0/16234.174.0.1 to 234.174.255.254234.174.255.25565,534
48234.175.0.0/16234.175.0.1 to 234.175.255.254234.175.255.25565,534
49234.176.0.0/16234.176.0.1 to 234.176.255.254234.176.255.25565,534
50234.177.0.0/16234.177.0.1 to 234.177.255.254234.177.255.25565,534
51234.178.0.0/16234.178.0.1 to 234.178.255.254234.178.255.25565,534
52234.179.0.0/16234.179.0.1 to 234.179.255.254234.179.255.25565,534
53234.180.0.0/16234.180.0.1 to 234.180.255.254234.180.255.25565,534
54234.181.0.0/16234.181.0.1 to 234.181.255.254234.181.255.25565,534
55234.182.0.0/16234.182.0.1 to 234.182.255.254234.182.255.25565,534
56234.183.0.0/16234.183.0.1 to 234.183.255.254234.183.255.25565,534
57234.184.0.0/16234.184.0.1 to 234.184.255.254234.184.255.25565,534
58234.185.0.0/16234.185.0.1 to 234.185.255.254234.185.255.25565,534
59234.186.0.0/16234.186.0.1 to 234.186.255.254234.186.255.25565,534
60234.187.0.0/16234.187.0.1 to 234.187.255.254234.187.255.25565,534
61234.188.0.0/16234.188.0.1 to 234.188.255.254234.188.255.25565,534
62234.189.0.0/16234.189.0.1 to 234.189.255.254234.189.255.25565,534
63234.190.0.0/16234.190.0.1 to 234.190.255.254234.190.255.25565,534
64234.191.0.0/16234.191.0.1 to 234.191.255.254234.191.255.25565,534

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.