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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.

Network199.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
199.0.0.0
Broadcast address
199.255.255.255
First usable
199.0.0.1
Last usable
199.255.255.254
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
C (default /24)
As numbers
Hex C7000000 · Integer 3338665984 to 3355443199
Reverse DNS zone
199.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11000111..00000000.00000000.00000000199.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network11000111..00000000.00000000.00000000199.0.0.0
Broadcast11000111..11111111.11111111.11111111199.255.255.255
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)

199.0.0.0/8 makes 64 subnets of /14.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1199.0.0.0/14199.0.0.1 to 199.3.255.254199.3.255.255262,142
2199.4.0.0/14199.4.0.1 to 199.7.255.254199.7.255.255262,142
3199.8.0.0/14199.8.0.1 to 199.11.255.254199.11.255.255262,142
4199.12.0.0/14199.12.0.1 to 199.15.255.254199.15.255.255262,142
5199.16.0.0/14199.16.0.1 to 199.19.255.254199.19.255.255262,142
6199.20.0.0/14199.20.0.1 to 199.23.255.254199.23.255.255262,142
7199.24.0.0/14199.24.0.1 to 199.27.255.254199.27.255.255262,142
8199.28.0.0/14199.28.0.1 to 199.31.255.254199.31.255.255262,142
9199.32.0.0/14199.32.0.1 to 199.35.255.254199.35.255.255262,142
10199.36.0.0/14199.36.0.1 to 199.39.255.254199.39.255.255262,142
11199.40.0.0/14199.40.0.1 to 199.43.255.254199.43.255.255262,142
12199.44.0.0/14199.44.0.1 to 199.47.255.254199.47.255.255262,142
13199.48.0.0/14199.48.0.1 to 199.51.255.254199.51.255.255262,142
14199.52.0.0/14199.52.0.1 to 199.55.255.254199.55.255.255262,142
15199.56.0.0/14199.56.0.1 to 199.59.255.254199.59.255.255262,142
16199.60.0.0/14199.60.0.1 to 199.63.255.254199.63.255.255262,142
17199.64.0.0/14199.64.0.1 to 199.67.255.254199.67.255.255262,142
18199.68.0.0/14199.68.0.1 to 199.71.255.254199.71.255.255262,142
19199.72.0.0/14199.72.0.1 to 199.75.255.254199.75.255.255262,142
20199.76.0.0/14199.76.0.1 to 199.79.255.254199.79.255.255262,142
21199.80.0.0/14199.80.0.1 to 199.83.255.254199.83.255.255262,142
22199.84.0.0/14199.84.0.1 to 199.87.255.254199.87.255.255262,142
23199.88.0.0/14199.88.0.1 to 199.91.255.254199.91.255.255262,142
24199.92.0.0/14199.92.0.1 to 199.95.255.254199.95.255.255262,142
25199.96.0.0/14199.96.0.1 to 199.99.255.254199.99.255.255262,142
26199.100.0.0/14199.100.0.1 to 199.103.255.254199.103.255.255262,142
27199.104.0.0/14199.104.0.1 to 199.107.255.254199.107.255.255262,142
28199.108.0.0/14199.108.0.1 to 199.111.255.254199.111.255.255262,142
29199.112.0.0/14199.112.0.1 to 199.115.255.254199.115.255.255262,142
30199.116.0.0/14199.116.0.1 to 199.119.255.254199.119.255.255262,142
31199.120.0.0/14199.120.0.1 to 199.123.255.254199.123.255.255262,142
32199.124.0.0/14199.124.0.1 to 199.127.255.254199.127.255.255262,142
33199.128.0.0/14199.128.0.1 to 199.131.255.254199.131.255.255262,142
34199.132.0.0/14199.132.0.1 to 199.135.255.254199.135.255.255262,142
35199.136.0.0/14199.136.0.1 to 199.139.255.254199.139.255.255262,142
36199.140.0.0/14199.140.0.1 to 199.143.255.254199.143.255.255262,142
37199.144.0.0/14199.144.0.1 to 199.147.255.254199.147.255.255262,142
38199.148.0.0/14199.148.0.1 to 199.151.255.254199.151.255.255262,142
39199.152.0.0/14199.152.0.1 to 199.155.255.254199.155.255.255262,142
40199.156.0.0/14199.156.0.1 to 199.159.255.254199.159.255.255262,142
41199.160.0.0/14199.160.0.1 to 199.163.255.254199.163.255.255262,142
42199.164.0.0/14199.164.0.1 to 199.167.255.254199.167.255.255262,142
43199.168.0.0/14199.168.0.1 to 199.171.255.254199.171.255.255262,142
44199.172.0.0/14199.172.0.1 to 199.175.255.254199.175.255.255262,142
45199.176.0.0/14199.176.0.1 to 199.179.255.254199.179.255.255262,142
46199.180.0.0/14199.180.0.1 to 199.183.255.254199.183.255.255262,142
47199.184.0.0/14199.184.0.1 to 199.187.255.254199.187.255.255262,142
48199.188.0.0/14199.188.0.1 to 199.191.255.254199.191.255.255262,142
49199.192.0.0/14199.192.0.1 to 199.195.255.254199.195.255.255262,142
50199.196.0.0/14199.196.0.1 to 199.199.255.254199.199.255.255262,142
51199.200.0.0/14199.200.0.1 to 199.203.255.254199.203.255.255262,142
52199.204.0.0/14199.204.0.1 to 199.207.255.254199.207.255.255262,142
53199.208.0.0/14199.208.0.1 to 199.211.255.254199.211.255.255262,142
54199.212.0.0/14199.212.0.1 to 199.215.255.254199.215.255.255262,142
55199.216.0.0/14199.216.0.1 to 199.219.255.254199.219.255.255262,142
56199.220.0.0/14199.220.0.1 to 199.223.255.254199.223.255.255262,142
57199.224.0.0/14199.224.0.1 to 199.227.255.254199.227.255.255262,142
58199.228.0.0/14199.228.0.1 to 199.231.255.254199.231.255.255262,142
59199.232.0.0/14199.232.0.1 to 199.235.255.254199.235.255.255262,142
60199.236.0.0/14199.236.0.1 to 199.239.255.254199.239.255.255262,142
61199.240.0.0/14199.240.0.1 to 199.243.255.254199.243.255.255262,142
62199.244.0.0/14199.244.0.1 to 199.247.255.254199.247.255.255262,142
63199.248.0.0/14199.248.0.1 to 199.251.255.254199.251.255.255262,142
64199.252.0.0/14199.252.0.1 to 199.255.255.254199.255.255.255262,142

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.