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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.

Network41.32.0.0/12
Usable hosts1,048,574
Subnet mask255.240.0.0
Addresses1,048,576
Network address
41.32.0.0
Broadcast address
41.47.255.255
First usable
41.32.0.1
Last usable
41.47.255.254
Usable hosts
1,048,574 (1,048,576 less the network and broadcast addresses)
Subnet mask
255.240.0.0
Wildcard mask
0.15.255.255 (Cisco ACLs, OSPF)
Prefix length
/12
Type
Public public
Old class
A (default /8)
As numbers
Hex 29200000 · Integer 689963008 to 691011583
Reverse DNS zones
32.41.in-addr.arpa
33.41.in-addr.arpa
34.41.in-addr.arpa
35.41.in-addr.arpa
36.41.in-addr.arpa
37.41.in-addr.arpa
38.41.in-addr.arpa
39.41.in-addr.arpa
40.41.in-addr.arpa
41.41.in-addr.arpa
42.41.in-addr.arpa
43.41.in-addr.arpa
44.41.in-addr.arpa
45.41.in-addr.arpa
46.41.in-addr.arpa
47.41.in-addr.arpa
/12 is not on a 8-bit boundary, so it takes 16 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00101001.00100000.00000000.0000000041.32.0.0
Subnet mask11111111.11110000.00000000.00000000255.240.0.0
Network00101001.00100000.00000000.0000000041.32.0.0
Broadcast00101001.00101111.11111111.1111111141.47.255.255
Split into smaller subnets/18
/13 (2)/14 (4)/15 (8)/16 (16)/17 (32)/18 (64)/19 (128)/20 (256)/21 (512)/22 (1,024)/23 (2,048)/24 (4,096)

41.32.0.0/12 makes 64 subnets of /18.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
141.32.0.0/1841.32.0.1 to 41.32.63.25441.32.63.25516,382
241.32.64.0/1841.32.64.1 to 41.32.127.25441.32.127.25516,382
341.32.128.0/1841.32.128.1 to 41.32.191.25441.32.191.25516,382
441.32.192.0/1841.32.192.1 to 41.32.255.25441.32.255.25516,382
541.33.0.0/1841.33.0.1 to 41.33.63.25441.33.63.25516,382
641.33.64.0/1841.33.64.1 to 41.33.127.25441.33.127.25516,382
741.33.128.0/1841.33.128.1 to 41.33.191.25441.33.191.25516,382
841.33.192.0/1841.33.192.1 to 41.33.255.25441.33.255.25516,382
941.34.0.0/1841.34.0.1 to 41.34.63.25441.34.63.25516,382
1041.34.64.0/1841.34.64.1 to 41.34.127.25441.34.127.25516,382
1141.34.128.0/1841.34.128.1 to 41.34.191.25441.34.191.25516,382
1241.34.192.0/1841.34.192.1 to 41.34.255.25441.34.255.25516,382
1341.35.0.0/1841.35.0.1 to 41.35.63.25441.35.63.25516,382
1441.35.64.0/1841.35.64.1 to 41.35.127.25441.35.127.25516,382
1541.35.128.0/1841.35.128.1 to 41.35.191.25441.35.191.25516,382
1641.35.192.0/1841.35.192.1 to 41.35.255.25441.35.255.25516,382
1741.36.0.0/1841.36.0.1 to 41.36.63.25441.36.63.25516,382
1841.36.64.0/1841.36.64.1 to 41.36.127.25441.36.127.25516,382
1941.36.128.0/1841.36.128.1 to 41.36.191.25441.36.191.25516,382
2041.36.192.0/1841.36.192.1 to 41.36.255.25441.36.255.25516,382
2141.37.0.0/1841.37.0.1 to 41.37.63.25441.37.63.25516,382
2241.37.64.0/1841.37.64.1 to 41.37.127.25441.37.127.25516,382
2341.37.128.0/1841.37.128.1 to 41.37.191.25441.37.191.25516,382
2441.37.192.0/1841.37.192.1 to 41.37.255.25441.37.255.25516,382
2541.38.0.0/1841.38.0.1 to 41.38.63.25441.38.63.25516,382
2641.38.64.0/1841.38.64.1 to 41.38.127.25441.38.127.25516,382
2741.38.128.0/1841.38.128.1 to 41.38.191.25441.38.191.25516,382
2841.38.192.0/1841.38.192.1 to 41.38.255.25441.38.255.25516,382
2941.39.0.0/1841.39.0.1 to 41.39.63.25441.39.63.25516,382
3041.39.64.0/1841.39.64.1 to 41.39.127.25441.39.127.25516,382
3141.39.128.0/1841.39.128.1 to 41.39.191.25441.39.191.25516,382
3241.39.192.0/1841.39.192.1 to 41.39.255.25441.39.255.25516,382
3341.40.0.0/1841.40.0.1 to 41.40.63.25441.40.63.25516,382
3441.40.64.0/1841.40.64.1 to 41.40.127.25441.40.127.25516,382
3541.40.128.0/1841.40.128.1 to 41.40.191.25441.40.191.25516,382
3641.40.192.0/1841.40.192.1 to 41.40.255.25441.40.255.25516,382
3741.41.0.0/1841.41.0.1 to 41.41.63.25441.41.63.25516,382
3841.41.64.0/1841.41.64.1 to 41.41.127.25441.41.127.25516,382
3941.41.128.0/1841.41.128.1 to 41.41.191.25441.41.191.25516,382
4041.41.192.0/1841.41.192.1 to 41.41.255.25441.41.255.25516,382
4141.42.0.0/1841.42.0.1 to 41.42.63.25441.42.63.25516,382
4241.42.64.0/1841.42.64.1 to 41.42.127.25441.42.127.25516,382
4341.42.128.0/1841.42.128.1 to 41.42.191.25441.42.191.25516,382
4441.42.192.0/1841.42.192.1 to 41.42.255.25441.42.255.25516,382
4541.43.0.0/1841.43.0.1 to 41.43.63.25441.43.63.25516,382
4641.43.64.0/1841.43.64.1 to 41.43.127.25441.43.127.25516,382
4741.43.128.0/1841.43.128.1 to 41.43.191.25441.43.191.25516,382
4841.43.192.0/1841.43.192.1 to 41.43.255.25441.43.255.25516,382
4941.44.0.0/1841.44.0.1 to 41.44.63.25441.44.63.25516,382
5041.44.64.0/1841.44.64.1 to 41.44.127.25441.44.127.25516,382
5141.44.128.0/1841.44.128.1 to 41.44.191.25441.44.191.25516,382
5241.44.192.0/1841.44.192.1 to 41.44.255.25441.44.255.25516,382
5341.45.0.0/1841.45.0.1 to 41.45.63.25441.45.63.25516,382
5441.45.64.0/1841.45.64.1 to 41.45.127.25441.45.127.25516,382
5541.45.128.0/1841.45.128.1 to 41.45.191.25441.45.191.25516,382
5641.45.192.0/1841.45.192.1 to 41.45.255.25441.45.255.25516,382
5741.46.0.0/1841.46.0.1 to 41.46.63.25441.46.63.25516,382
5841.46.64.0/1841.46.64.1 to 41.46.127.25441.46.127.25516,382
5941.46.128.0/1841.46.128.1 to 41.46.191.25441.46.191.25516,382
6041.46.192.0/1841.46.192.1 to 41.46.255.25441.46.255.25516,382
6141.47.0.0/1841.47.0.1 to 41.47.63.25441.47.63.25516,382
6241.47.64.0/1841.47.64.1 to 41.47.127.25441.47.127.25516,382
6341.47.128.0/1841.47.128.1 to 41.47.191.25441.47.191.25516,382
6441.47.192.0/1841.47.192.1 to 41.47.255.25441.47.255.25516,382

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.