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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.

Network153.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
153.0.0.0
Broadcast address
153.255.255.255
First usable
153.0.0.1
Last usable
153.255.255.254
Usable hosts
16,777,214 (16,777,216 less the network and broadcast addresses)
Subnet mask
255.0.0.0
Wildcard mask
0.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/8
Type
Public public
Old class
B (default /16)
As numbers
Hex 99000000 · Integer 2566914048 to 2583691263
Reverse DNS zone
153.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10011001..00000000.00000000.00000000153.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network10011001..00000000.00000000.00000000153.0.0.0
Broadcast10011001..11111111.11111111.11111111153.255.255.255
Split into smaller subnets/14
/9 (2)/10 (4)/11 (8)/12 (16)/13 (32)/14 (64)/15 (128)/16 (256)/17 (512)/18 (1,024)/19 (2,048)/20 (4,096)

153.0.0.0/8 makes 64 subnets of /14.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1153.0.0.0/14153.0.0.1 to 153.3.255.254153.3.255.255262,142
2153.4.0.0/14153.4.0.1 to 153.7.255.254153.7.255.255262,142
3153.8.0.0/14153.8.0.1 to 153.11.255.254153.11.255.255262,142
4153.12.0.0/14153.12.0.1 to 153.15.255.254153.15.255.255262,142
5153.16.0.0/14153.16.0.1 to 153.19.255.254153.19.255.255262,142
6153.20.0.0/14153.20.0.1 to 153.23.255.254153.23.255.255262,142
7153.24.0.0/14153.24.0.1 to 153.27.255.254153.27.255.255262,142
8153.28.0.0/14153.28.0.1 to 153.31.255.254153.31.255.255262,142
9153.32.0.0/14153.32.0.1 to 153.35.255.254153.35.255.255262,142
10153.36.0.0/14153.36.0.1 to 153.39.255.254153.39.255.255262,142
11153.40.0.0/14153.40.0.1 to 153.43.255.254153.43.255.255262,142
12153.44.0.0/14153.44.0.1 to 153.47.255.254153.47.255.255262,142
13153.48.0.0/14153.48.0.1 to 153.51.255.254153.51.255.255262,142
14153.52.0.0/14153.52.0.1 to 153.55.255.254153.55.255.255262,142
15153.56.0.0/14153.56.0.1 to 153.59.255.254153.59.255.255262,142
16153.60.0.0/14153.60.0.1 to 153.63.255.254153.63.255.255262,142
17153.64.0.0/14153.64.0.1 to 153.67.255.254153.67.255.255262,142
18153.68.0.0/14153.68.0.1 to 153.71.255.254153.71.255.255262,142
19153.72.0.0/14153.72.0.1 to 153.75.255.254153.75.255.255262,142
20153.76.0.0/14153.76.0.1 to 153.79.255.254153.79.255.255262,142
21153.80.0.0/14153.80.0.1 to 153.83.255.254153.83.255.255262,142
22153.84.0.0/14153.84.0.1 to 153.87.255.254153.87.255.255262,142
23153.88.0.0/14153.88.0.1 to 153.91.255.254153.91.255.255262,142
24153.92.0.0/14153.92.0.1 to 153.95.255.254153.95.255.255262,142
25153.96.0.0/14153.96.0.1 to 153.99.255.254153.99.255.255262,142
26153.100.0.0/14153.100.0.1 to 153.103.255.254153.103.255.255262,142
27153.104.0.0/14153.104.0.1 to 153.107.255.254153.107.255.255262,142
28153.108.0.0/14153.108.0.1 to 153.111.255.254153.111.255.255262,142
29153.112.0.0/14153.112.0.1 to 153.115.255.254153.115.255.255262,142
30153.116.0.0/14153.116.0.1 to 153.119.255.254153.119.255.255262,142
31153.120.0.0/14153.120.0.1 to 153.123.255.254153.123.255.255262,142
32153.124.0.0/14153.124.0.1 to 153.127.255.254153.127.255.255262,142
33153.128.0.0/14153.128.0.1 to 153.131.255.254153.131.255.255262,142
34153.132.0.0/14153.132.0.1 to 153.135.255.254153.135.255.255262,142
35153.136.0.0/14153.136.0.1 to 153.139.255.254153.139.255.255262,142
36153.140.0.0/14153.140.0.1 to 153.143.255.254153.143.255.255262,142
37153.144.0.0/14153.144.0.1 to 153.147.255.254153.147.255.255262,142
38153.148.0.0/14153.148.0.1 to 153.151.255.254153.151.255.255262,142
39153.152.0.0/14153.152.0.1 to 153.155.255.254153.155.255.255262,142
40153.156.0.0/14153.156.0.1 to 153.159.255.254153.159.255.255262,142
41153.160.0.0/14153.160.0.1 to 153.163.255.254153.163.255.255262,142
42153.164.0.0/14153.164.0.1 to 153.167.255.254153.167.255.255262,142
43153.168.0.0/14153.168.0.1 to 153.171.255.254153.171.255.255262,142
44153.172.0.0/14153.172.0.1 to 153.175.255.254153.175.255.255262,142
45153.176.0.0/14153.176.0.1 to 153.179.255.254153.179.255.255262,142
46153.180.0.0/14153.180.0.1 to 153.183.255.254153.183.255.255262,142
47153.184.0.0/14153.184.0.1 to 153.187.255.254153.187.255.255262,142
48153.188.0.0/14153.188.0.1 to 153.191.255.254153.191.255.255262,142
49153.192.0.0/14153.192.0.1 to 153.195.255.254153.195.255.255262,142
50153.196.0.0/14153.196.0.1 to 153.199.255.254153.199.255.255262,142
51153.200.0.0/14153.200.0.1 to 153.203.255.254153.203.255.255262,142
52153.204.0.0/14153.204.0.1 to 153.207.255.254153.207.255.255262,142
53153.208.0.0/14153.208.0.1 to 153.211.255.254153.211.255.255262,142
54153.212.0.0/14153.212.0.1 to 153.215.255.254153.215.255.255262,142
55153.216.0.0/14153.216.0.1 to 153.219.255.254153.219.255.255262,142
56153.220.0.0/14153.220.0.1 to 153.223.255.254153.223.255.255262,142
57153.224.0.0/14153.224.0.1 to 153.227.255.254153.227.255.255262,142
58153.228.0.0/14153.228.0.1 to 153.231.255.254153.231.255.255262,142
59153.232.0.0/14153.232.0.1 to 153.235.255.254153.235.255.255262,142
60153.236.0.0/14153.236.0.1 to 153.239.255.254153.239.255.255262,142
61153.240.0.0/14153.240.0.1 to 153.243.255.254153.243.255.255262,142
62153.244.0.0/14153.244.0.1 to 153.247.255.254153.247.255.255262,142
63153.248.0.0/14153.248.0.1 to 153.251.255.254153.251.255.255262,142
64153.252.0.0/14153.252.0.1 to 153.255.255.254153.255.255.255262,142

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.