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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.

Network75.30.0.0/15
Usable hosts131,070
Subnet mask255.254.0.0
Addresses131,072
Network address
75.30.0.0
Broadcast address
75.31.255.255
First usable
75.30.0.1
Last usable
75.31.255.254
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 4B1E0000 · Integer 1260257280 to 1260388351
Reverse DNS zones
30.75.in-addr.arpa
31.75.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
Address01001011.00011110.00000000.0000000075.30.0.0
Subnet mask11111111.11111110.00000000.00000000255.254.0.0
Network01001011.00011110.00000000.0000000075.30.0.0
Broadcast01001011.00011111.11111111.1111111175.31.255.255
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)

75.30.0.0/15 makes 128 subnets of /22.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
175.30.0.0/2275.30.0.1 to 75.30.3.25475.30.3.2551,022
275.30.4.0/2275.30.4.1 to 75.30.7.25475.30.7.2551,022
375.30.8.0/2275.30.8.1 to 75.30.11.25475.30.11.2551,022
475.30.12.0/2275.30.12.1 to 75.30.15.25475.30.15.2551,022
575.30.16.0/2275.30.16.1 to 75.30.19.25475.30.19.2551,022
675.30.20.0/2275.30.20.1 to 75.30.23.25475.30.23.2551,022
775.30.24.0/2275.30.24.1 to 75.30.27.25475.30.27.2551,022
875.30.28.0/2275.30.28.1 to 75.30.31.25475.30.31.2551,022
975.30.32.0/2275.30.32.1 to 75.30.35.25475.30.35.2551,022
1075.30.36.0/2275.30.36.1 to 75.30.39.25475.30.39.2551,022
1175.30.40.0/2275.30.40.1 to 75.30.43.25475.30.43.2551,022
1275.30.44.0/2275.30.44.1 to 75.30.47.25475.30.47.2551,022
1375.30.48.0/2275.30.48.1 to 75.30.51.25475.30.51.2551,022
1475.30.52.0/2275.30.52.1 to 75.30.55.25475.30.55.2551,022
1575.30.56.0/2275.30.56.1 to 75.30.59.25475.30.59.2551,022
1675.30.60.0/2275.30.60.1 to 75.30.63.25475.30.63.2551,022
1775.30.64.0/2275.30.64.1 to 75.30.67.25475.30.67.2551,022
1875.30.68.0/2275.30.68.1 to 75.30.71.25475.30.71.2551,022
1975.30.72.0/2275.30.72.1 to 75.30.75.25475.30.75.2551,022
2075.30.76.0/2275.30.76.1 to 75.30.79.25475.30.79.2551,022
2175.30.80.0/2275.30.80.1 to 75.30.83.25475.30.83.2551,022
2275.30.84.0/2275.30.84.1 to 75.30.87.25475.30.87.2551,022
2375.30.88.0/2275.30.88.1 to 75.30.91.25475.30.91.2551,022
2475.30.92.0/2275.30.92.1 to 75.30.95.25475.30.95.2551,022
2575.30.96.0/2275.30.96.1 to 75.30.99.25475.30.99.2551,022
2675.30.100.0/2275.30.100.1 to 75.30.103.25475.30.103.2551,022
2775.30.104.0/2275.30.104.1 to 75.30.107.25475.30.107.2551,022
2875.30.108.0/2275.30.108.1 to 75.30.111.25475.30.111.2551,022
2975.30.112.0/2275.30.112.1 to 75.30.115.25475.30.115.2551,022
3075.30.116.0/2275.30.116.1 to 75.30.119.25475.30.119.2551,022
3175.30.120.0/2275.30.120.1 to 75.30.123.25475.30.123.2551,022
3275.30.124.0/2275.30.124.1 to 75.30.127.25475.30.127.2551,022
3375.30.128.0/2275.30.128.1 to 75.30.131.25475.30.131.2551,022
3475.30.132.0/2275.30.132.1 to 75.30.135.25475.30.135.2551,022
3575.30.136.0/2275.30.136.1 to 75.30.139.25475.30.139.2551,022
3675.30.140.0/2275.30.140.1 to 75.30.143.25475.30.143.2551,022
3775.30.144.0/2275.30.144.1 to 75.30.147.25475.30.147.2551,022
3875.30.148.0/2275.30.148.1 to 75.30.151.25475.30.151.2551,022
3975.30.152.0/2275.30.152.1 to 75.30.155.25475.30.155.2551,022
4075.30.156.0/2275.30.156.1 to 75.30.159.25475.30.159.2551,022
4175.30.160.0/2275.30.160.1 to 75.30.163.25475.30.163.2551,022
4275.30.164.0/2275.30.164.1 to 75.30.167.25475.30.167.2551,022
4375.30.168.0/2275.30.168.1 to 75.30.171.25475.30.171.2551,022
4475.30.172.0/2275.30.172.1 to 75.30.175.25475.30.175.2551,022
4575.30.176.0/2275.30.176.1 to 75.30.179.25475.30.179.2551,022
4675.30.180.0/2275.30.180.1 to 75.30.183.25475.30.183.2551,022
4775.30.184.0/2275.30.184.1 to 75.30.187.25475.30.187.2551,022
4875.30.188.0/2275.30.188.1 to 75.30.191.25475.30.191.2551,022
4975.30.192.0/2275.30.192.1 to 75.30.195.25475.30.195.2551,022
5075.30.196.0/2275.30.196.1 to 75.30.199.25475.30.199.2551,022
5175.30.200.0/2275.30.200.1 to 75.30.203.25475.30.203.2551,022
5275.30.204.0/2275.30.204.1 to 75.30.207.25475.30.207.2551,022
5375.30.208.0/2275.30.208.1 to 75.30.211.25475.30.211.2551,022
5475.30.212.0/2275.30.212.1 to 75.30.215.25475.30.215.2551,022
5575.30.216.0/2275.30.216.1 to 75.30.219.25475.30.219.2551,022
5675.30.220.0/2275.30.220.1 to 75.30.223.25475.30.223.2551,022
5775.30.224.0/2275.30.224.1 to 75.30.227.25475.30.227.2551,022
5875.30.228.0/2275.30.228.1 to 75.30.231.25475.30.231.2551,022
5975.30.232.0/2275.30.232.1 to 75.30.235.25475.30.235.2551,022
6075.30.236.0/2275.30.236.1 to 75.30.239.25475.30.239.2551,022
6175.30.240.0/2275.30.240.1 to 75.30.243.25475.30.243.2551,022
6275.30.244.0/2275.30.244.1 to 75.30.247.25475.30.247.2551,022
6375.30.248.0/2275.30.248.1 to 75.30.251.25475.30.251.2551,022
6475.30.252.0/2275.30.252.1 to 75.30.255.25475.30.255.2551,022
6575.31.0.0/2275.31.0.1 to 75.31.3.25475.31.3.2551,022
6675.31.4.0/2275.31.4.1 to 75.31.7.25475.31.7.2551,022
6775.31.8.0/2275.31.8.1 to 75.31.11.25475.31.11.2551,022
6875.31.12.0/2275.31.12.1 to 75.31.15.25475.31.15.2551,022
6975.31.16.0/2275.31.16.1 to 75.31.19.25475.31.19.2551,022
7075.31.20.0/2275.31.20.1 to 75.31.23.25475.31.23.2551,022
7175.31.24.0/2275.31.24.1 to 75.31.27.25475.31.27.2551,022
7275.31.28.0/2275.31.28.1 to 75.31.31.25475.31.31.2551,022
7375.31.32.0/2275.31.32.1 to 75.31.35.25475.31.35.2551,022
7475.31.36.0/2275.31.36.1 to 75.31.39.25475.31.39.2551,022
7575.31.40.0/2275.31.40.1 to 75.31.43.25475.31.43.2551,022
7675.31.44.0/2275.31.44.1 to 75.31.47.25475.31.47.2551,022
7775.31.48.0/2275.31.48.1 to 75.31.51.25475.31.51.2551,022
7875.31.52.0/2275.31.52.1 to 75.31.55.25475.31.55.2551,022
7975.31.56.0/2275.31.56.1 to 75.31.59.25475.31.59.2551,022
8075.31.60.0/2275.31.60.1 to 75.31.63.25475.31.63.2551,022
8175.31.64.0/2275.31.64.1 to 75.31.67.25475.31.67.2551,022
8275.31.68.0/2275.31.68.1 to 75.31.71.25475.31.71.2551,022
8375.31.72.0/2275.31.72.1 to 75.31.75.25475.31.75.2551,022
8475.31.76.0/2275.31.76.1 to 75.31.79.25475.31.79.2551,022
8575.31.80.0/2275.31.80.1 to 75.31.83.25475.31.83.2551,022
8675.31.84.0/2275.31.84.1 to 75.31.87.25475.31.87.2551,022
8775.31.88.0/2275.31.88.1 to 75.31.91.25475.31.91.2551,022
8875.31.92.0/2275.31.92.1 to 75.31.95.25475.31.95.2551,022
8975.31.96.0/2275.31.96.1 to 75.31.99.25475.31.99.2551,022
9075.31.100.0/2275.31.100.1 to 75.31.103.25475.31.103.2551,022
9175.31.104.0/2275.31.104.1 to 75.31.107.25475.31.107.2551,022
9275.31.108.0/2275.31.108.1 to 75.31.111.25475.31.111.2551,022
9375.31.112.0/2275.31.112.1 to 75.31.115.25475.31.115.2551,022
9475.31.116.0/2275.31.116.1 to 75.31.119.25475.31.119.2551,022
9575.31.120.0/2275.31.120.1 to 75.31.123.25475.31.123.2551,022
9675.31.124.0/2275.31.124.1 to 75.31.127.25475.31.127.2551,022
9775.31.128.0/2275.31.128.1 to 75.31.131.25475.31.131.2551,022
9875.31.132.0/2275.31.132.1 to 75.31.135.25475.31.135.2551,022
9975.31.136.0/2275.31.136.1 to 75.31.139.25475.31.139.2551,022
10075.31.140.0/2275.31.140.1 to 75.31.143.25475.31.143.2551,022
10175.31.144.0/2275.31.144.1 to 75.31.147.25475.31.147.2551,022
10275.31.148.0/2275.31.148.1 to 75.31.151.25475.31.151.2551,022
10375.31.152.0/2275.31.152.1 to 75.31.155.25475.31.155.2551,022
10475.31.156.0/2275.31.156.1 to 75.31.159.25475.31.159.2551,022
10575.31.160.0/2275.31.160.1 to 75.31.163.25475.31.163.2551,022
10675.31.164.0/2275.31.164.1 to 75.31.167.25475.31.167.2551,022
10775.31.168.0/2275.31.168.1 to 75.31.171.25475.31.171.2551,022
10875.31.172.0/2275.31.172.1 to 75.31.175.25475.31.175.2551,022
10975.31.176.0/2275.31.176.1 to 75.31.179.25475.31.179.2551,022
11075.31.180.0/2275.31.180.1 to 75.31.183.25475.31.183.2551,022
11175.31.184.0/2275.31.184.1 to 75.31.187.25475.31.187.2551,022
11275.31.188.0/2275.31.188.1 to 75.31.191.25475.31.191.2551,022
11375.31.192.0/2275.31.192.1 to 75.31.195.25475.31.195.2551,022
11475.31.196.0/2275.31.196.1 to 75.31.199.25475.31.199.2551,022
11575.31.200.0/2275.31.200.1 to 75.31.203.25475.31.203.2551,022
11675.31.204.0/2275.31.204.1 to 75.31.207.25475.31.207.2551,022
11775.31.208.0/2275.31.208.1 to 75.31.211.25475.31.211.2551,022
11875.31.212.0/2275.31.212.1 to 75.31.215.25475.31.215.2551,022
11975.31.216.0/2275.31.216.1 to 75.31.219.25475.31.219.2551,022
12075.31.220.0/2275.31.220.1 to 75.31.223.25475.31.223.2551,022
12175.31.224.0/2275.31.224.1 to 75.31.227.25475.31.227.2551,022
12275.31.228.0/2275.31.228.1 to 75.31.231.25475.31.231.2551,022
12375.31.232.0/2275.31.232.1 to 75.31.235.25475.31.235.2551,022
12475.31.236.0/2275.31.236.1 to 75.31.239.25475.31.239.2551,022
12575.31.240.0/2275.31.240.1 to 75.31.243.25475.31.243.2551,022
12675.31.244.0/2275.31.244.1 to 75.31.247.25475.31.247.2551,022
12775.31.248.0/2275.31.248.1 to 75.31.251.25475.31.251.2551,022
12875.31.252.0/2275.31.252.1 to 75.31.255.25475.31.255.2551,022

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.