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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.

Network48.0.0.0/9
Usable hosts8,388,606
Subnet mask255.128.0.0
Addresses8,388,608
Network address
48.0.0.0
Broadcast address
48.127.255.255
First usable
48.0.0.1
Last usable
48.127.255.254
Usable hosts
8,388,606 (8,388,608 less the network and broadcast addresses)
Subnet mask
255.128.0.0
Wildcard mask
0.127.255.255 (Cisco ACLs, OSPF)
Prefix length
/9
Type
Public public
Old class
A (default /8)
As numbers
Hex 30000000 · Integer 805306368 to 813694975
Reverse DNS zones
0.48.in-addr.arpa
1.48.in-addr.arpa
2.48.in-addr.arpa
3.48.in-addr.arpa
4.48.in-addr.arpa
5.48.in-addr.arpa
6.48.in-addr.arpa
7.48.in-addr.arpa
8.48.in-addr.arpa
9.48.in-addr.arpa
10.48.in-addr.arpa
11.48.in-addr.arpa
12.48.in-addr.arpa
13.48.in-addr.arpa
14.48.in-addr.arpa
15.48.in-addr.arpa
and 112 more
/9 is not on a 8-bit boundary, so it takes 128 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00110000.00000000.00000000.0000000048.0.0.0
Subnet mask11111111.10000000.00000000.00000000255.128.0.0
Network00110000.00000000.00000000.0000000048.0.0.0
Broadcast00110000.01111111.11111111.1111111148.127.255.255
Split into smaller subnets/15
/10 (2)/11 (4)/12 (8)/13 (16)/14 (32)/15 (64)/16 (128)/17 (256)/18 (512)/19 (1,024)/20 (2,048)/21 (4,096)

48.0.0.0/9 makes 64 subnets of /15.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
148.0.0.0/1548.0.0.1 to 48.1.255.25448.1.255.255131,070
248.2.0.0/1548.2.0.1 to 48.3.255.25448.3.255.255131,070
348.4.0.0/1548.4.0.1 to 48.5.255.25448.5.255.255131,070
448.6.0.0/1548.6.0.1 to 48.7.255.25448.7.255.255131,070
548.8.0.0/1548.8.0.1 to 48.9.255.25448.9.255.255131,070
648.10.0.0/1548.10.0.1 to 48.11.255.25448.11.255.255131,070
748.12.0.0/1548.12.0.1 to 48.13.255.25448.13.255.255131,070
848.14.0.0/1548.14.0.1 to 48.15.255.25448.15.255.255131,070
948.16.0.0/1548.16.0.1 to 48.17.255.25448.17.255.255131,070
1048.18.0.0/1548.18.0.1 to 48.19.255.25448.19.255.255131,070
1148.20.0.0/1548.20.0.1 to 48.21.255.25448.21.255.255131,070
1248.22.0.0/1548.22.0.1 to 48.23.255.25448.23.255.255131,070
1348.24.0.0/1548.24.0.1 to 48.25.255.25448.25.255.255131,070
1448.26.0.0/1548.26.0.1 to 48.27.255.25448.27.255.255131,070
1548.28.0.0/1548.28.0.1 to 48.29.255.25448.29.255.255131,070
1648.30.0.0/1548.30.0.1 to 48.31.255.25448.31.255.255131,070
1748.32.0.0/1548.32.0.1 to 48.33.255.25448.33.255.255131,070
1848.34.0.0/1548.34.0.1 to 48.35.255.25448.35.255.255131,070
1948.36.0.0/1548.36.0.1 to 48.37.255.25448.37.255.255131,070
2048.38.0.0/1548.38.0.1 to 48.39.255.25448.39.255.255131,070
2148.40.0.0/1548.40.0.1 to 48.41.255.25448.41.255.255131,070
2248.42.0.0/1548.42.0.1 to 48.43.255.25448.43.255.255131,070
2348.44.0.0/1548.44.0.1 to 48.45.255.25448.45.255.255131,070
2448.46.0.0/1548.46.0.1 to 48.47.255.25448.47.255.255131,070
2548.48.0.0/1548.48.0.1 to 48.49.255.25448.49.255.255131,070
2648.50.0.0/1548.50.0.1 to 48.51.255.25448.51.255.255131,070
2748.52.0.0/1548.52.0.1 to 48.53.255.25448.53.255.255131,070
2848.54.0.0/1548.54.0.1 to 48.55.255.25448.55.255.255131,070
2948.56.0.0/1548.56.0.1 to 48.57.255.25448.57.255.255131,070
3048.58.0.0/1548.58.0.1 to 48.59.255.25448.59.255.255131,070
3148.60.0.0/1548.60.0.1 to 48.61.255.25448.61.255.255131,070
3248.62.0.0/1548.62.0.1 to 48.63.255.25448.63.255.255131,070
3348.64.0.0/1548.64.0.1 to 48.65.255.25448.65.255.255131,070
3448.66.0.0/1548.66.0.1 to 48.67.255.25448.67.255.255131,070
3548.68.0.0/1548.68.0.1 to 48.69.255.25448.69.255.255131,070
3648.70.0.0/1548.70.0.1 to 48.71.255.25448.71.255.255131,070
3748.72.0.0/1548.72.0.1 to 48.73.255.25448.73.255.255131,070
3848.74.0.0/1548.74.0.1 to 48.75.255.25448.75.255.255131,070
3948.76.0.0/1548.76.0.1 to 48.77.255.25448.77.255.255131,070
4048.78.0.0/1548.78.0.1 to 48.79.255.25448.79.255.255131,070
4148.80.0.0/1548.80.0.1 to 48.81.255.25448.81.255.255131,070
4248.82.0.0/1548.82.0.1 to 48.83.255.25448.83.255.255131,070
4348.84.0.0/1548.84.0.1 to 48.85.255.25448.85.255.255131,070
4448.86.0.0/1548.86.0.1 to 48.87.255.25448.87.255.255131,070
4548.88.0.0/1548.88.0.1 to 48.89.255.25448.89.255.255131,070
4648.90.0.0/1548.90.0.1 to 48.91.255.25448.91.255.255131,070
4748.92.0.0/1548.92.0.1 to 48.93.255.25448.93.255.255131,070
4848.94.0.0/1548.94.0.1 to 48.95.255.25448.95.255.255131,070
4948.96.0.0/1548.96.0.1 to 48.97.255.25448.97.255.255131,070
5048.98.0.0/1548.98.0.1 to 48.99.255.25448.99.255.255131,070
5148.100.0.0/1548.100.0.1 to 48.101.255.25448.101.255.255131,070
5248.102.0.0/1548.102.0.1 to 48.103.255.25448.103.255.255131,070
5348.104.0.0/1548.104.0.1 to 48.105.255.25448.105.255.255131,070
5448.106.0.0/1548.106.0.1 to 48.107.255.25448.107.255.255131,070
5548.108.0.0/1548.108.0.1 to 48.109.255.25448.109.255.255131,070
5648.110.0.0/1548.110.0.1 to 48.111.255.25448.111.255.255131,070
5748.112.0.0/1548.112.0.1 to 48.113.255.25448.113.255.255131,070
5848.114.0.0/1548.114.0.1 to 48.115.255.25448.115.255.255131,070
5948.116.0.0/1548.116.0.1 to 48.117.255.25448.117.255.255131,070
6048.118.0.0/1548.118.0.1 to 48.119.255.25448.119.255.255131,070
6148.120.0.0/1548.120.0.1 to 48.121.255.25448.121.255.255131,070
6248.122.0.0/1548.122.0.1 to 48.123.255.25448.123.255.255131,070
6348.124.0.0/1548.124.0.1 to 48.125.255.25448.125.255.255131,070
6448.126.0.0/1548.126.0.1 to 48.127.255.25448.127.255.255131,070

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.