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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.

Network147.48.0.0/12
Usable hosts1,048,574
Subnet mask255.240.0.0
Addresses1,048,576
Network address
147.48.0.0
Broadcast address
147.63.255.255
First usable
147.48.0.1
Last usable
147.63.255.254
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
B (default /16)
As numbers
Hex 93300000 · Integer 2469396480 to 2470445055
Reverse DNS zones
48.147.in-addr.arpa
49.147.in-addr.arpa
50.147.in-addr.arpa
51.147.in-addr.arpa
52.147.in-addr.arpa
53.147.in-addr.arpa
54.147.in-addr.arpa
55.147.in-addr.arpa
56.147.in-addr.arpa
57.147.in-addr.arpa
58.147.in-addr.arpa
59.147.in-addr.arpa
60.147.in-addr.arpa
61.147.in-addr.arpa
62.147.in-addr.arpa
63.147.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
Address10010011.00110000.00000000.00000000147.48.0.0
Subnet mask11111111.11110000.00000000.00000000255.240.0.0
Network10010011.00110000.00000000.00000000147.48.0.0
Broadcast10010011.00111111.11111111.11111111147.63.255.255
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)

147.48.0.0/12 makes 64 subnets of /18.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1147.48.0.0/18147.48.0.1 to 147.48.63.254147.48.63.25516,382
2147.48.64.0/18147.48.64.1 to 147.48.127.254147.48.127.25516,382
3147.48.128.0/18147.48.128.1 to 147.48.191.254147.48.191.25516,382
4147.48.192.0/18147.48.192.1 to 147.48.255.254147.48.255.25516,382
5147.49.0.0/18147.49.0.1 to 147.49.63.254147.49.63.25516,382
6147.49.64.0/18147.49.64.1 to 147.49.127.254147.49.127.25516,382
7147.49.128.0/18147.49.128.1 to 147.49.191.254147.49.191.25516,382
8147.49.192.0/18147.49.192.1 to 147.49.255.254147.49.255.25516,382
9147.50.0.0/18147.50.0.1 to 147.50.63.254147.50.63.25516,382
10147.50.64.0/18147.50.64.1 to 147.50.127.254147.50.127.25516,382
11147.50.128.0/18147.50.128.1 to 147.50.191.254147.50.191.25516,382
12147.50.192.0/18147.50.192.1 to 147.50.255.254147.50.255.25516,382
13147.51.0.0/18147.51.0.1 to 147.51.63.254147.51.63.25516,382
14147.51.64.0/18147.51.64.1 to 147.51.127.254147.51.127.25516,382
15147.51.128.0/18147.51.128.1 to 147.51.191.254147.51.191.25516,382
16147.51.192.0/18147.51.192.1 to 147.51.255.254147.51.255.25516,382
17147.52.0.0/18147.52.0.1 to 147.52.63.254147.52.63.25516,382
18147.52.64.0/18147.52.64.1 to 147.52.127.254147.52.127.25516,382
19147.52.128.0/18147.52.128.1 to 147.52.191.254147.52.191.25516,382
20147.52.192.0/18147.52.192.1 to 147.52.255.254147.52.255.25516,382
21147.53.0.0/18147.53.0.1 to 147.53.63.254147.53.63.25516,382
22147.53.64.0/18147.53.64.1 to 147.53.127.254147.53.127.25516,382
23147.53.128.0/18147.53.128.1 to 147.53.191.254147.53.191.25516,382
24147.53.192.0/18147.53.192.1 to 147.53.255.254147.53.255.25516,382
25147.54.0.0/18147.54.0.1 to 147.54.63.254147.54.63.25516,382
26147.54.64.0/18147.54.64.1 to 147.54.127.254147.54.127.25516,382
27147.54.128.0/18147.54.128.1 to 147.54.191.254147.54.191.25516,382
28147.54.192.0/18147.54.192.1 to 147.54.255.254147.54.255.25516,382
29147.55.0.0/18147.55.0.1 to 147.55.63.254147.55.63.25516,382
30147.55.64.0/18147.55.64.1 to 147.55.127.254147.55.127.25516,382
31147.55.128.0/18147.55.128.1 to 147.55.191.254147.55.191.25516,382
32147.55.192.0/18147.55.192.1 to 147.55.255.254147.55.255.25516,382
33147.56.0.0/18147.56.0.1 to 147.56.63.254147.56.63.25516,382
34147.56.64.0/18147.56.64.1 to 147.56.127.254147.56.127.25516,382
35147.56.128.0/18147.56.128.1 to 147.56.191.254147.56.191.25516,382
36147.56.192.0/18147.56.192.1 to 147.56.255.254147.56.255.25516,382
37147.57.0.0/18147.57.0.1 to 147.57.63.254147.57.63.25516,382
38147.57.64.0/18147.57.64.1 to 147.57.127.254147.57.127.25516,382
39147.57.128.0/18147.57.128.1 to 147.57.191.254147.57.191.25516,382
40147.57.192.0/18147.57.192.1 to 147.57.255.254147.57.255.25516,382
41147.58.0.0/18147.58.0.1 to 147.58.63.254147.58.63.25516,382
42147.58.64.0/18147.58.64.1 to 147.58.127.254147.58.127.25516,382
43147.58.128.0/18147.58.128.1 to 147.58.191.254147.58.191.25516,382
44147.58.192.0/18147.58.192.1 to 147.58.255.254147.58.255.25516,382
45147.59.0.0/18147.59.0.1 to 147.59.63.254147.59.63.25516,382
46147.59.64.0/18147.59.64.1 to 147.59.127.254147.59.127.25516,382
47147.59.128.0/18147.59.128.1 to 147.59.191.254147.59.191.25516,382
48147.59.192.0/18147.59.192.1 to 147.59.255.254147.59.255.25516,382
49147.60.0.0/18147.60.0.1 to 147.60.63.254147.60.63.25516,382
50147.60.64.0/18147.60.64.1 to 147.60.127.254147.60.127.25516,382
51147.60.128.0/18147.60.128.1 to 147.60.191.254147.60.191.25516,382
52147.60.192.0/18147.60.192.1 to 147.60.255.254147.60.255.25516,382
53147.61.0.0/18147.61.0.1 to 147.61.63.254147.61.63.25516,382
54147.61.64.0/18147.61.64.1 to 147.61.127.254147.61.127.25516,382
55147.61.128.0/18147.61.128.1 to 147.61.191.254147.61.191.25516,382
56147.61.192.0/18147.61.192.1 to 147.61.255.254147.61.255.25516,382
57147.62.0.0/18147.62.0.1 to 147.62.63.254147.62.63.25516,382
58147.62.64.0/18147.62.64.1 to 147.62.127.254147.62.127.25516,382
59147.62.128.0/18147.62.128.1 to 147.62.191.254147.62.191.25516,382
60147.62.192.0/18147.62.192.1 to 147.62.255.254147.62.255.25516,382
61147.63.0.0/18147.63.0.1 to 147.63.63.254147.63.63.25516,382
62147.63.64.0/18147.63.64.1 to 147.63.127.254147.63.127.25516,382
63147.63.128.0/18147.63.128.1 to 147.63.191.254147.63.191.25516,382
64147.63.192.0/18147.63.192.1 to 147.63.255.254147.63.255.25516,382

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.