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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.

Network52.8.0.0/18
Usable hosts16,382
Subnet mask255.255.192.0
Addresses16,384
Network address
52.8.0.0
Broadcast address
52.8.63.255
First usable
52.8.0.1
Last usable
52.8.63.254
Usable hosts
16,382 (16,384 less the network and broadcast addresses)
Subnet mask
255.255.192.0
Wildcard mask
0.0.63.255 (Cisco ACLs, OSPF)
Prefix length
/18
Type
Public public
Old class
A (default /8)
As numbers
Hex 34080000 · Integer 872939520 to 872955903
Reverse DNS zones
0.8.52.in-addr.arpa
1.8.52.in-addr.arpa
2.8.52.in-addr.arpa
3.8.52.in-addr.arpa
4.8.52.in-addr.arpa
5.8.52.in-addr.arpa
6.8.52.in-addr.arpa
7.8.52.in-addr.arpa
8.8.52.in-addr.arpa
9.8.52.in-addr.arpa
10.8.52.in-addr.arpa
11.8.52.in-addr.arpa
12.8.52.in-addr.arpa
13.8.52.in-addr.arpa
14.8.52.in-addr.arpa
15.8.52.in-addr.arpa
and 48 more
/18 is not on a 8-bit boundary, so it takes 64 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00110100.00001000.00000000.0000000052.8.0.0
Subnet mask11111111.11111111.11000000.00000000255.255.192.0
Network00110100.00001000.00000000.0000000052.8.0.0
Broadcast00110100.00001000.00111111.1111111152.8.63.255
Split into smaller subnets/25
/19 (2)/20 (4)/21 (8)/22 (16)/23 (32)/24 (64)/25 (128)/26 (256)/27 (512)/28 (1,024)/29 (2,048)/30 (4,096)

52.8.0.0/18 makes 128 subnets of /25.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
152.8.0.0/2552.8.0.1 to 52.8.0.12652.8.0.127126
252.8.0.128/2552.8.0.129 to 52.8.0.25452.8.0.255126
352.8.1.0/2552.8.1.1 to 52.8.1.12652.8.1.127126
452.8.1.128/2552.8.1.129 to 52.8.1.25452.8.1.255126
552.8.2.0/2552.8.2.1 to 52.8.2.12652.8.2.127126
652.8.2.128/2552.8.2.129 to 52.8.2.25452.8.2.255126
752.8.3.0/2552.8.3.1 to 52.8.3.12652.8.3.127126
852.8.3.128/2552.8.3.129 to 52.8.3.25452.8.3.255126
952.8.4.0/2552.8.4.1 to 52.8.4.12652.8.4.127126
1052.8.4.128/2552.8.4.129 to 52.8.4.25452.8.4.255126
1152.8.5.0/2552.8.5.1 to 52.8.5.12652.8.5.127126
1252.8.5.128/2552.8.5.129 to 52.8.5.25452.8.5.255126
1352.8.6.0/2552.8.6.1 to 52.8.6.12652.8.6.127126
1452.8.6.128/2552.8.6.129 to 52.8.6.25452.8.6.255126
1552.8.7.0/2552.8.7.1 to 52.8.7.12652.8.7.127126
1652.8.7.128/2552.8.7.129 to 52.8.7.25452.8.7.255126
1752.8.8.0/2552.8.8.1 to 52.8.8.12652.8.8.127126
1852.8.8.128/2552.8.8.129 to 52.8.8.25452.8.8.255126
1952.8.9.0/2552.8.9.1 to 52.8.9.12652.8.9.127126
2052.8.9.128/2552.8.9.129 to 52.8.9.25452.8.9.255126
2152.8.10.0/2552.8.10.1 to 52.8.10.12652.8.10.127126
2252.8.10.128/2552.8.10.129 to 52.8.10.25452.8.10.255126
2352.8.11.0/2552.8.11.1 to 52.8.11.12652.8.11.127126
2452.8.11.128/2552.8.11.129 to 52.8.11.25452.8.11.255126
2552.8.12.0/2552.8.12.1 to 52.8.12.12652.8.12.127126
2652.8.12.128/2552.8.12.129 to 52.8.12.25452.8.12.255126
2752.8.13.0/2552.8.13.1 to 52.8.13.12652.8.13.127126
2852.8.13.128/2552.8.13.129 to 52.8.13.25452.8.13.255126
2952.8.14.0/2552.8.14.1 to 52.8.14.12652.8.14.127126
3052.8.14.128/2552.8.14.129 to 52.8.14.25452.8.14.255126
3152.8.15.0/2552.8.15.1 to 52.8.15.12652.8.15.127126
3252.8.15.128/2552.8.15.129 to 52.8.15.25452.8.15.255126
3352.8.16.0/2552.8.16.1 to 52.8.16.12652.8.16.127126
3452.8.16.128/2552.8.16.129 to 52.8.16.25452.8.16.255126
3552.8.17.0/2552.8.17.1 to 52.8.17.12652.8.17.127126
3652.8.17.128/2552.8.17.129 to 52.8.17.25452.8.17.255126
3752.8.18.0/2552.8.18.1 to 52.8.18.12652.8.18.127126
3852.8.18.128/2552.8.18.129 to 52.8.18.25452.8.18.255126
3952.8.19.0/2552.8.19.1 to 52.8.19.12652.8.19.127126
4052.8.19.128/2552.8.19.129 to 52.8.19.25452.8.19.255126
4152.8.20.0/2552.8.20.1 to 52.8.20.12652.8.20.127126
4252.8.20.128/2552.8.20.129 to 52.8.20.25452.8.20.255126
4352.8.21.0/2552.8.21.1 to 52.8.21.12652.8.21.127126
4452.8.21.128/2552.8.21.129 to 52.8.21.25452.8.21.255126
4552.8.22.0/2552.8.22.1 to 52.8.22.12652.8.22.127126
4652.8.22.128/2552.8.22.129 to 52.8.22.25452.8.22.255126
4752.8.23.0/2552.8.23.1 to 52.8.23.12652.8.23.127126
4852.8.23.128/2552.8.23.129 to 52.8.23.25452.8.23.255126
4952.8.24.0/2552.8.24.1 to 52.8.24.12652.8.24.127126
5052.8.24.128/2552.8.24.129 to 52.8.24.25452.8.24.255126
5152.8.25.0/2552.8.25.1 to 52.8.25.12652.8.25.127126
5252.8.25.128/2552.8.25.129 to 52.8.25.25452.8.25.255126
5352.8.26.0/2552.8.26.1 to 52.8.26.12652.8.26.127126
5452.8.26.128/2552.8.26.129 to 52.8.26.25452.8.26.255126
5552.8.27.0/2552.8.27.1 to 52.8.27.12652.8.27.127126
5652.8.27.128/2552.8.27.129 to 52.8.27.25452.8.27.255126
5752.8.28.0/2552.8.28.1 to 52.8.28.12652.8.28.127126
5852.8.28.128/2552.8.28.129 to 52.8.28.25452.8.28.255126
5952.8.29.0/2552.8.29.1 to 52.8.29.12652.8.29.127126
6052.8.29.128/2552.8.29.129 to 52.8.29.25452.8.29.255126
6152.8.30.0/2552.8.30.1 to 52.8.30.12652.8.30.127126
6252.8.30.128/2552.8.30.129 to 52.8.30.25452.8.30.255126
6352.8.31.0/2552.8.31.1 to 52.8.31.12652.8.31.127126
6452.8.31.128/2552.8.31.129 to 52.8.31.25452.8.31.255126
6552.8.32.0/2552.8.32.1 to 52.8.32.12652.8.32.127126
6652.8.32.128/2552.8.32.129 to 52.8.32.25452.8.32.255126
6752.8.33.0/2552.8.33.1 to 52.8.33.12652.8.33.127126
6852.8.33.128/2552.8.33.129 to 52.8.33.25452.8.33.255126
6952.8.34.0/2552.8.34.1 to 52.8.34.12652.8.34.127126
7052.8.34.128/2552.8.34.129 to 52.8.34.25452.8.34.255126
7152.8.35.0/2552.8.35.1 to 52.8.35.12652.8.35.127126
7252.8.35.128/2552.8.35.129 to 52.8.35.25452.8.35.255126
7352.8.36.0/2552.8.36.1 to 52.8.36.12652.8.36.127126
7452.8.36.128/2552.8.36.129 to 52.8.36.25452.8.36.255126
7552.8.37.0/2552.8.37.1 to 52.8.37.12652.8.37.127126
7652.8.37.128/2552.8.37.129 to 52.8.37.25452.8.37.255126
7752.8.38.0/2552.8.38.1 to 52.8.38.12652.8.38.127126
7852.8.38.128/2552.8.38.129 to 52.8.38.25452.8.38.255126
7952.8.39.0/2552.8.39.1 to 52.8.39.12652.8.39.127126
8052.8.39.128/2552.8.39.129 to 52.8.39.25452.8.39.255126
8152.8.40.0/2552.8.40.1 to 52.8.40.12652.8.40.127126
8252.8.40.128/2552.8.40.129 to 52.8.40.25452.8.40.255126
8352.8.41.0/2552.8.41.1 to 52.8.41.12652.8.41.127126
8452.8.41.128/2552.8.41.129 to 52.8.41.25452.8.41.255126
8552.8.42.0/2552.8.42.1 to 52.8.42.12652.8.42.127126
8652.8.42.128/2552.8.42.129 to 52.8.42.25452.8.42.255126
8752.8.43.0/2552.8.43.1 to 52.8.43.12652.8.43.127126
8852.8.43.128/2552.8.43.129 to 52.8.43.25452.8.43.255126
8952.8.44.0/2552.8.44.1 to 52.8.44.12652.8.44.127126
9052.8.44.128/2552.8.44.129 to 52.8.44.25452.8.44.255126
9152.8.45.0/2552.8.45.1 to 52.8.45.12652.8.45.127126
9252.8.45.128/2552.8.45.129 to 52.8.45.25452.8.45.255126
9352.8.46.0/2552.8.46.1 to 52.8.46.12652.8.46.127126
9452.8.46.128/2552.8.46.129 to 52.8.46.25452.8.46.255126
9552.8.47.0/2552.8.47.1 to 52.8.47.12652.8.47.127126
9652.8.47.128/2552.8.47.129 to 52.8.47.25452.8.47.255126
9752.8.48.0/2552.8.48.1 to 52.8.48.12652.8.48.127126
9852.8.48.128/2552.8.48.129 to 52.8.48.25452.8.48.255126
9952.8.49.0/2552.8.49.1 to 52.8.49.12652.8.49.127126
10052.8.49.128/2552.8.49.129 to 52.8.49.25452.8.49.255126
10152.8.50.0/2552.8.50.1 to 52.8.50.12652.8.50.127126
10252.8.50.128/2552.8.50.129 to 52.8.50.25452.8.50.255126
10352.8.51.0/2552.8.51.1 to 52.8.51.12652.8.51.127126
10452.8.51.128/2552.8.51.129 to 52.8.51.25452.8.51.255126
10552.8.52.0/2552.8.52.1 to 52.8.52.12652.8.52.127126
10652.8.52.128/2552.8.52.129 to 52.8.52.25452.8.52.255126
10752.8.53.0/2552.8.53.1 to 52.8.53.12652.8.53.127126
10852.8.53.128/2552.8.53.129 to 52.8.53.25452.8.53.255126
10952.8.54.0/2552.8.54.1 to 52.8.54.12652.8.54.127126
11052.8.54.128/2552.8.54.129 to 52.8.54.25452.8.54.255126
11152.8.55.0/2552.8.55.1 to 52.8.55.12652.8.55.127126
11252.8.55.128/2552.8.55.129 to 52.8.55.25452.8.55.255126
11352.8.56.0/2552.8.56.1 to 52.8.56.12652.8.56.127126
11452.8.56.128/2552.8.56.129 to 52.8.56.25452.8.56.255126
11552.8.57.0/2552.8.57.1 to 52.8.57.12652.8.57.127126
11652.8.57.128/2552.8.57.129 to 52.8.57.25452.8.57.255126
11752.8.58.0/2552.8.58.1 to 52.8.58.12652.8.58.127126
11852.8.58.128/2552.8.58.129 to 52.8.58.25452.8.58.255126
11952.8.59.0/2552.8.59.1 to 52.8.59.12652.8.59.127126
12052.8.59.128/2552.8.59.129 to 52.8.59.25452.8.59.255126
12152.8.60.0/2552.8.60.1 to 52.8.60.12652.8.60.127126
12252.8.60.128/2552.8.60.129 to 52.8.60.25452.8.60.255126
12352.8.61.0/2552.8.61.1 to 52.8.61.12652.8.61.127126
12452.8.61.128/2552.8.61.129 to 52.8.61.25452.8.61.255126
12552.8.62.0/2552.8.62.1 to 52.8.62.12652.8.62.127126
12652.8.62.128/2552.8.62.129 to 52.8.62.25452.8.62.255126
12752.8.63.0/2552.8.63.1 to 52.8.63.12652.8.63.127126
12852.8.63.128/2552.8.63.129 to 52.8.63.25452.8.63.255126

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.