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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.

Network30.26.0.0/15
Usable hosts131,070
Subnet mask255.254.0.0
Addresses131,072
Network address
30.26.0.0
Broadcast address
30.27.255.255
First usable
30.26.0.1
Last usable
30.27.255.254
Usable hosts
131,070 (131,072 less the network and broadcast addresses)
Subnet mask
255.254.0.0
Wildcard mask
0.1.255.255 (Cisco ACLs, OSPF)
Prefix length
/15
Type
Public public
Old class
A (default /8)
As numbers
Hex 1E1A0000 · Integer 505020416 to 505151487
Reverse DNS zones
26.30.in-addr.arpa
27.30.in-addr.arpa
/15 is not on a 8-bit boundary, so it takes 2 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00011110.00011010.00000000.0000000030.26.0.0
Subnet mask11111111.11111110.00000000.00000000255.254.0.0
Network00011110.00011010.00000000.0000000030.26.0.0
Broadcast00011110.00011011.11111111.1111111130.27.255.255
Split into smaller subnets/22
/16 (2)/17 (4)/18 (8)/19 (16)/20 (32)/21 (64)/22 (128)/23 (256)/24 (512)/25 (1,024)/26 (2,048)/27 (4,096)

30.26.0.0/15 makes 128 subnets of /22.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
130.26.0.0/2230.26.0.1 to 30.26.3.25430.26.3.2551,022
230.26.4.0/2230.26.4.1 to 30.26.7.25430.26.7.2551,022
330.26.8.0/2230.26.8.1 to 30.26.11.25430.26.11.2551,022
430.26.12.0/2230.26.12.1 to 30.26.15.25430.26.15.2551,022
530.26.16.0/2230.26.16.1 to 30.26.19.25430.26.19.2551,022
630.26.20.0/2230.26.20.1 to 30.26.23.25430.26.23.2551,022
730.26.24.0/2230.26.24.1 to 30.26.27.25430.26.27.2551,022
830.26.28.0/2230.26.28.1 to 30.26.31.25430.26.31.2551,022
930.26.32.0/2230.26.32.1 to 30.26.35.25430.26.35.2551,022
1030.26.36.0/2230.26.36.1 to 30.26.39.25430.26.39.2551,022
1130.26.40.0/2230.26.40.1 to 30.26.43.25430.26.43.2551,022
1230.26.44.0/2230.26.44.1 to 30.26.47.25430.26.47.2551,022
1330.26.48.0/2230.26.48.1 to 30.26.51.25430.26.51.2551,022
1430.26.52.0/2230.26.52.1 to 30.26.55.25430.26.55.2551,022
1530.26.56.0/2230.26.56.1 to 30.26.59.25430.26.59.2551,022
1630.26.60.0/2230.26.60.1 to 30.26.63.25430.26.63.2551,022
1730.26.64.0/2230.26.64.1 to 30.26.67.25430.26.67.2551,022
1830.26.68.0/2230.26.68.1 to 30.26.71.25430.26.71.2551,022
1930.26.72.0/2230.26.72.1 to 30.26.75.25430.26.75.2551,022
2030.26.76.0/2230.26.76.1 to 30.26.79.25430.26.79.2551,022
2130.26.80.0/2230.26.80.1 to 30.26.83.25430.26.83.2551,022
2230.26.84.0/2230.26.84.1 to 30.26.87.25430.26.87.2551,022
2330.26.88.0/2230.26.88.1 to 30.26.91.25430.26.91.2551,022
2430.26.92.0/2230.26.92.1 to 30.26.95.25430.26.95.2551,022
2530.26.96.0/2230.26.96.1 to 30.26.99.25430.26.99.2551,022
2630.26.100.0/2230.26.100.1 to 30.26.103.25430.26.103.2551,022
2730.26.104.0/2230.26.104.1 to 30.26.107.25430.26.107.2551,022
2830.26.108.0/2230.26.108.1 to 30.26.111.25430.26.111.2551,022
2930.26.112.0/2230.26.112.1 to 30.26.115.25430.26.115.2551,022
3030.26.116.0/2230.26.116.1 to 30.26.119.25430.26.119.2551,022
3130.26.120.0/2230.26.120.1 to 30.26.123.25430.26.123.2551,022
3230.26.124.0/2230.26.124.1 to 30.26.127.25430.26.127.2551,022
3330.26.128.0/2230.26.128.1 to 30.26.131.25430.26.131.2551,022
3430.26.132.0/2230.26.132.1 to 30.26.135.25430.26.135.2551,022
3530.26.136.0/2230.26.136.1 to 30.26.139.25430.26.139.2551,022
3630.26.140.0/2230.26.140.1 to 30.26.143.25430.26.143.2551,022
3730.26.144.0/2230.26.144.1 to 30.26.147.25430.26.147.2551,022
3830.26.148.0/2230.26.148.1 to 30.26.151.25430.26.151.2551,022
3930.26.152.0/2230.26.152.1 to 30.26.155.25430.26.155.2551,022
4030.26.156.0/2230.26.156.1 to 30.26.159.25430.26.159.2551,022
4130.26.160.0/2230.26.160.1 to 30.26.163.25430.26.163.2551,022
4230.26.164.0/2230.26.164.1 to 30.26.167.25430.26.167.2551,022
4330.26.168.0/2230.26.168.1 to 30.26.171.25430.26.171.2551,022
4430.26.172.0/2230.26.172.1 to 30.26.175.25430.26.175.2551,022
4530.26.176.0/2230.26.176.1 to 30.26.179.25430.26.179.2551,022
4630.26.180.0/2230.26.180.1 to 30.26.183.25430.26.183.2551,022
4730.26.184.0/2230.26.184.1 to 30.26.187.25430.26.187.2551,022
4830.26.188.0/2230.26.188.1 to 30.26.191.25430.26.191.2551,022
4930.26.192.0/2230.26.192.1 to 30.26.195.25430.26.195.2551,022
5030.26.196.0/2230.26.196.1 to 30.26.199.25430.26.199.2551,022
5130.26.200.0/2230.26.200.1 to 30.26.203.25430.26.203.2551,022
5230.26.204.0/2230.26.204.1 to 30.26.207.25430.26.207.2551,022
5330.26.208.0/2230.26.208.1 to 30.26.211.25430.26.211.2551,022
5430.26.212.0/2230.26.212.1 to 30.26.215.25430.26.215.2551,022
5530.26.216.0/2230.26.216.1 to 30.26.219.25430.26.219.2551,022
5630.26.220.0/2230.26.220.1 to 30.26.223.25430.26.223.2551,022
5730.26.224.0/2230.26.224.1 to 30.26.227.25430.26.227.2551,022
5830.26.228.0/2230.26.228.1 to 30.26.231.25430.26.231.2551,022
5930.26.232.0/2230.26.232.1 to 30.26.235.25430.26.235.2551,022
6030.26.236.0/2230.26.236.1 to 30.26.239.25430.26.239.2551,022
6130.26.240.0/2230.26.240.1 to 30.26.243.25430.26.243.2551,022
6230.26.244.0/2230.26.244.1 to 30.26.247.25430.26.247.2551,022
6330.26.248.0/2230.26.248.1 to 30.26.251.25430.26.251.2551,022
6430.26.252.0/2230.26.252.1 to 30.26.255.25430.26.255.2551,022
6530.27.0.0/2230.27.0.1 to 30.27.3.25430.27.3.2551,022
6630.27.4.0/2230.27.4.1 to 30.27.7.25430.27.7.2551,022
6730.27.8.0/2230.27.8.1 to 30.27.11.25430.27.11.2551,022
6830.27.12.0/2230.27.12.1 to 30.27.15.25430.27.15.2551,022
6930.27.16.0/2230.27.16.1 to 30.27.19.25430.27.19.2551,022
7030.27.20.0/2230.27.20.1 to 30.27.23.25430.27.23.2551,022
7130.27.24.0/2230.27.24.1 to 30.27.27.25430.27.27.2551,022
7230.27.28.0/2230.27.28.1 to 30.27.31.25430.27.31.2551,022
7330.27.32.0/2230.27.32.1 to 30.27.35.25430.27.35.2551,022
7430.27.36.0/2230.27.36.1 to 30.27.39.25430.27.39.2551,022
7530.27.40.0/2230.27.40.1 to 30.27.43.25430.27.43.2551,022
7630.27.44.0/2230.27.44.1 to 30.27.47.25430.27.47.2551,022
7730.27.48.0/2230.27.48.1 to 30.27.51.25430.27.51.2551,022
7830.27.52.0/2230.27.52.1 to 30.27.55.25430.27.55.2551,022
7930.27.56.0/2230.27.56.1 to 30.27.59.25430.27.59.2551,022
8030.27.60.0/2230.27.60.1 to 30.27.63.25430.27.63.2551,022
8130.27.64.0/2230.27.64.1 to 30.27.67.25430.27.67.2551,022
8230.27.68.0/2230.27.68.1 to 30.27.71.25430.27.71.2551,022
8330.27.72.0/2230.27.72.1 to 30.27.75.25430.27.75.2551,022
8430.27.76.0/2230.27.76.1 to 30.27.79.25430.27.79.2551,022
8530.27.80.0/2230.27.80.1 to 30.27.83.25430.27.83.2551,022
8630.27.84.0/2230.27.84.1 to 30.27.87.25430.27.87.2551,022
8730.27.88.0/2230.27.88.1 to 30.27.91.25430.27.91.2551,022
8830.27.92.0/2230.27.92.1 to 30.27.95.25430.27.95.2551,022
8930.27.96.0/2230.27.96.1 to 30.27.99.25430.27.99.2551,022
9030.27.100.0/2230.27.100.1 to 30.27.103.25430.27.103.2551,022
9130.27.104.0/2230.27.104.1 to 30.27.107.25430.27.107.2551,022
9230.27.108.0/2230.27.108.1 to 30.27.111.25430.27.111.2551,022
9330.27.112.0/2230.27.112.1 to 30.27.115.25430.27.115.2551,022
9430.27.116.0/2230.27.116.1 to 30.27.119.25430.27.119.2551,022
9530.27.120.0/2230.27.120.1 to 30.27.123.25430.27.123.2551,022
9630.27.124.0/2230.27.124.1 to 30.27.127.25430.27.127.2551,022
9730.27.128.0/2230.27.128.1 to 30.27.131.25430.27.131.2551,022
9830.27.132.0/2230.27.132.1 to 30.27.135.25430.27.135.2551,022
9930.27.136.0/2230.27.136.1 to 30.27.139.25430.27.139.2551,022
10030.27.140.0/2230.27.140.1 to 30.27.143.25430.27.143.2551,022
10130.27.144.0/2230.27.144.1 to 30.27.147.25430.27.147.2551,022
10230.27.148.0/2230.27.148.1 to 30.27.151.25430.27.151.2551,022
10330.27.152.0/2230.27.152.1 to 30.27.155.25430.27.155.2551,022
10430.27.156.0/2230.27.156.1 to 30.27.159.25430.27.159.2551,022
10530.27.160.0/2230.27.160.1 to 30.27.163.25430.27.163.2551,022
10630.27.164.0/2230.27.164.1 to 30.27.167.25430.27.167.2551,022
10730.27.168.0/2230.27.168.1 to 30.27.171.25430.27.171.2551,022
10830.27.172.0/2230.27.172.1 to 30.27.175.25430.27.175.2551,022
10930.27.176.0/2230.27.176.1 to 30.27.179.25430.27.179.2551,022
11030.27.180.0/2230.27.180.1 to 30.27.183.25430.27.183.2551,022
11130.27.184.0/2230.27.184.1 to 30.27.187.25430.27.187.2551,022
11230.27.188.0/2230.27.188.1 to 30.27.191.25430.27.191.2551,022
11330.27.192.0/2230.27.192.1 to 30.27.195.25430.27.195.2551,022
11430.27.196.0/2230.27.196.1 to 30.27.199.25430.27.199.2551,022
11530.27.200.0/2230.27.200.1 to 30.27.203.25430.27.203.2551,022
11630.27.204.0/2230.27.204.1 to 30.27.207.25430.27.207.2551,022
11730.27.208.0/2230.27.208.1 to 30.27.211.25430.27.211.2551,022
11830.27.212.0/2230.27.212.1 to 30.27.215.25430.27.215.2551,022
11930.27.216.0/2230.27.216.1 to 30.27.219.25430.27.219.2551,022
12030.27.220.0/2230.27.220.1 to 30.27.223.25430.27.223.2551,022
12130.27.224.0/2230.27.224.1 to 30.27.227.25430.27.227.2551,022
12230.27.228.0/2230.27.228.1 to 30.27.231.25430.27.231.2551,022
12330.27.232.0/2230.27.232.1 to 30.27.235.25430.27.235.2551,022
12430.27.236.0/2230.27.236.1 to 30.27.239.25430.27.239.2551,022
12530.27.240.0/2230.27.240.1 to 30.27.243.25430.27.243.2551,022
12630.27.244.0/2230.27.244.1 to 30.27.247.25430.27.247.2551,022
12730.27.248.0/2230.27.248.1 to 30.27.251.25430.27.251.2551,022
12830.27.252.0/2230.27.252.1 to 30.27.255.25430.27.255.2551,022

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.