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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.

Network87.24.0.0/13
Usable hosts524,286
Subnet mask255.248.0.0
Addresses524,288
Network address
87.24.0.0
Broadcast address
87.31.255.255
First usable
87.24.0.1
Last usable
87.31.255.254
Usable hosts
524,286 (524,288 less the network and broadcast addresses)
Subnet mask
255.248.0.0
Wildcard mask
0.7.255.255 (Cisco ACLs, OSPF)
Prefix length
/13
Type
Public public
Old class
A (default /8)
As numbers
Hex 57180000 · Integer 1461190656 to 1461714943
Reverse DNS zones
24.87.in-addr.arpa
25.87.in-addr.arpa
26.87.in-addr.arpa
27.87.in-addr.arpa
28.87.in-addr.arpa
29.87.in-addr.arpa
30.87.in-addr.arpa
31.87.in-addr.arpa
/13 is not on a 8-bit boundary, so it takes 8 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01010111.00011000.00000000.0000000087.24.0.0
Subnet mask11111111.11111000.00000000.00000000255.248.0.0
Network01010111.00011000.00000000.0000000087.24.0.0
Broadcast01010111.00011111.11111111.1111111187.31.255.255
Split into smaller subnets/20
/14 (2)/15 (4)/16 (8)/17 (16)/18 (32)/19 (64)/20 (128)/21 (256)/22 (512)/23 (1,024)/24 (2,048)/25 (4,096)

87.24.0.0/13 makes 128 subnets of /20.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
187.24.0.0/2087.24.0.1 to 87.24.15.25487.24.15.2554,094
287.24.16.0/2087.24.16.1 to 87.24.31.25487.24.31.2554,094
387.24.32.0/2087.24.32.1 to 87.24.47.25487.24.47.2554,094
487.24.48.0/2087.24.48.1 to 87.24.63.25487.24.63.2554,094
587.24.64.0/2087.24.64.1 to 87.24.79.25487.24.79.2554,094
687.24.80.0/2087.24.80.1 to 87.24.95.25487.24.95.2554,094
787.24.96.0/2087.24.96.1 to 87.24.111.25487.24.111.2554,094
887.24.112.0/2087.24.112.1 to 87.24.127.25487.24.127.2554,094
987.24.128.0/2087.24.128.1 to 87.24.143.25487.24.143.2554,094
1087.24.144.0/2087.24.144.1 to 87.24.159.25487.24.159.2554,094
1187.24.160.0/2087.24.160.1 to 87.24.175.25487.24.175.2554,094
1287.24.176.0/2087.24.176.1 to 87.24.191.25487.24.191.2554,094
1387.24.192.0/2087.24.192.1 to 87.24.207.25487.24.207.2554,094
1487.24.208.0/2087.24.208.1 to 87.24.223.25487.24.223.2554,094
1587.24.224.0/2087.24.224.1 to 87.24.239.25487.24.239.2554,094
1687.24.240.0/2087.24.240.1 to 87.24.255.25487.24.255.2554,094
1787.25.0.0/2087.25.0.1 to 87.25.15.25487.25.15.2554,094
1887.25.16.0/2087.25.16.1 to 87.25.31.25487.25.31.2554,094
1987.25.32.0/2087.25.32.1 to 87.25.47.25487.25.47.2554,094
2087.25.48.0/2087.25.48.1 to 87.25.63.25487.25.63.2554,094
2187.25.64.0/2087.25.64.1 to 87.25.79.25487.25.79.2554,094
2287.25.80.0/2087.25.80.1 to 87.25.95.25487.25.95.2554,094
2387.25.96.0/2087.25.96.1 to 87.25.111.25487.25.111.2554,094
2487.25.112.0/2087.25.112.1 to 87.25.127.25487.25.127.2554,094
2587.25.128.0/2087.25.128.1 to 87.25.143.25487.25.143.2554,094
2687.25.144.0/2087.25.144.1 to 87.25.159.25487.25.159.2554,094
2787.25.160.0/2087.25.160.1 to 87.25.175.25487.25.175.2554,094
2887.25.176.0/2087.25.176.1 to 87.25.191.25487.25.191.2554,094
2987.25.192.0/2087.25.192.1 to 87.25.207.25487.25.207.2554,094
3087.25.208.0/2087.25.208.1 to 87.25.223.25487.25.223.2554,094
3187.25.224.0/2087.25.224.1 to 87.25.239.25487.25.239.2554,094
3287.25.240.0/2087.25.240.1 to 87.25.255.25487.25.255.2554,094
3387.26.0.0/2087.26.0.1 to 87.26.15.25487.26.15.2554,094
3487.26.16.0/2087.26.16.1 to 87.26.31.25487.26.31.2554,094
3587.26.32.0/2087.26.32.1 to 87.26.47.25487.26.47.2554,094
3687.26.48.0/2087.26.48.1 to 87.26.63.25487.26.63.2554,094
3787.26.64.0/2087.26.64.1 to 87.26.79.25487.26.79.2554,094
3887.26.80.0/2087.26.80.1 to 87.26.95.25487.26.95.2554,094
3987.26.96.0/2087.26.96.1 to 87.26.111.25487.26.111.2554,094
4087.26.112.0/2087.26.112.1 to 87.26.127.25487.26.127.2554,094
4187.26.128.0/2087.26.128.1 to 87.26.143.25487.26.143.2554,094
4287.26.144.0/2087.26.144.1 to 87.26.159.25487.26.159.2554,094
4387.26.160.0/2087.26.160.1 to 87.26.175.25487.26.175.2554,094
4487.26.176.0/2087.26.176.1 to 87.26.191.25487.26.191.2554,094
4587.26.192.0/2087.26.192.1 to 87.26.207.25487.26.207.2554,094
4687.26.208.0/2087.26.208.1 to 87.26.223.25487.26.223.2554,094
4787.26.224.0/2087.26.224.1 to 87.26.239.25487.26.239.2554,094
4887.26.240.0/2087.26.240.1 to 87.26.255.25487.26.255.2554,094
4987.27.0.0/2087.27.0.1 to 87.27.15.25487.27.15.2554,094
5087.27.16.0/2087.27.16.1 to 87.27.31.25487.27.31.2554,094
5187.27.32.0/2087.27.32.1 to 87.27.47.25487.27.47.2554,094
5287.27.48.0/2087.27.48.1 to 87.27.63.25487.27.63.2554,094
5387.27.64.0/2087.27.64.1 to 87.27.79.25487.27.79.2554,094
5487.27.80.0/2087.27.80.1 to 87.27.95.25487.27.95.2554,094
5587.27.96.0/2087.27.96.1 to 87.27.111.25487.27.111.2554,094
5687.27.112.0/2087.27.112.1 to 87.27.127.25487.27.127.2554,094
5787.27.128.0/2087.27.128.1 to 87.27.143.25487.27.143.2554,094
5887.27.144.0/2087.27.144.1 to 87.27.159.25487.27.159.2554,094
5987.27.160.0/2087.27.160.1 to 87.27.175.25487.27.175.2554,094
6087.27.176.0/2087.27.176.1 to 87.27.191.25487.27.191.2554,094
6187.27.192.0/2087.27.192.1 to 87.27.207.25487.27.207.2554,094
6287.27.208.0/2087.27.208.1 to 87.27.223.25487.27.223.2554,094
6387.27.224.0/2087.27.224.1 to 87.27.239.25487.27.239.2554,094
6487.27.240.0/2087.27.240.1 to 87.27.255.25487.27.255.2554,094
6587.28.0.0/2087.28.0.1 to 87.28.15.25487.28.15.2554,094
6687.28.16.0/2087.28.16.1 to 87.28.31.25487.28.31.2554,094
6787.28.32.0/2087.28.32.1 to 87.28.47.25487.28.47.2554,094
6887.28.48.0/2087.28.48.1 to 87.28.63.25487.28.63.2554,094
6987.28.64.0/2087.28.64.1 to 87.28.79.25487.28.79.2554,094
7087.28.80.0/2087.28.80.1 to 87.28.95.25487.28.95.2554,094
7187.28.96.0/2087.28.96.1 to 87.28.111.25487.28.111.2554,094
7287.28.112.0/2087.28.112.1 to 87.28.127.25487.28.127.2554,094
7387.28.128.0/2087.28.128.1 to 87.28.143.25487.28.143.2554,094
7487.28.144.0/2087.28.144.1 to 87.28.159.25487.28.159.2554,094
7587.28.160.0/2087.28.160.1 to 87.28.175.25487.28.175.2554,094
7687.28.176.0/2087.28.176.1 to 87.28.191.25487.28.191.2554,094
7787.28.192.0/2087.28.192.1 to 87.28.207.25487.28.207.2554,094
7887.28.208.0/2087.28.208.1 to 87.28.223.25487.28.223.2554,094
7987.28.224.0/2087.28.224.1 to 87.28.239.25487.28.239.2554,094
8087.28.240.0/2087.28.240.1 to 87.28.255.25487.28.255.2554,094
8187.29.0.0/2087.29.0.1 to 87.29.15.25487.29.15.2554,094
8287.29.16.0/2087.29.16.1 to 87.29.31.25487.29.31.2554,094
8387.29.32.0/2087.29.32.1 to 87.29.47.25487.29.47.2554,094
8487.29.48.0/2087.29.48.1 to 87.29.63.25487.29.63.2554,094
8587.29.64.0/2087.29.64.1 to 87.29.79.25487.29.79.2554,094
8687.29.80.0/2087.29.80.1 to 87.29.95.25487.29.95.2554,094
8787.29.96.0/2087.29.96.1 to 87.29.111.25487.29.111.2554,094
8887.29.112.0/2087.29.112.1 to 87.29.127.25487.29.127.2554,094
8987.29.128.0/2087.29.128.1 to 87.29.143.25487.29.143.2554,094
9087.29.144.0/2087.29.144.1 to 87.29.159.25487.29.159.2554,094
9187.29.160.0/2087.29.160.1 to 87.29.175.25487.29.175.2554,094
9287.29.176.0/2087.29.176.1 to 87.29.191.25487.29.191.2554,094
9387.29.192.0/2087.29.192.1 to 87.29.207.25487.29.207.2554,094
9487.29.208.0/2087.29.208.1 to 87.29.223.25487.29.223.2554,094
9587.29.224.0/2087.29.224.1 to 87.29.239.25487.29.239.2554,094
9687.29.240.0/2087.29.240.1 to 87.29.255.25487.29.255.2554,094
9787.30.0.0/2087.30.0.1 to 87.30.15.25487.30.15.2554,094
9887.30.16.0/2087.30.16.1 to 87.30.31.25487.30.31.2554,094
9987.30.32.0/2087.30.32.1 to 87.30.47.25487.30.47.2554,094
10087.30.48.0/2087.30.48.1 to 87.30.63.25487.30.63.2554,094
10187.30.64.0/2087.30.64.1 to 87.30.79.25487.30.79.2554,094
10287.30.80.0/2087.30.80.1 to 87.30.95.25487.30.95.2554,094
10387.30.96.0/2087.30.96.1 to 87.30.111.25487.30.111.2554,094
10487.30.112.0/2087.30.112.1 to 87.30.127.25487.30.127.2554,094
10587.30.128.0/2087.30.128.1 to 87.30.143.25487.30.143.2554,094
10687.30.144.0/2087.30.144.1 to 87.30.159.25487.30.159.2554,094
10787.30.160.0/2087.30.160.1 to 87.30.175.25487.30.175.2554,094
10887.30.176.0/2087.30.176.1 to 87.30.191.25487.30.191.2554,094
10987.30.192.0/2087.30.192.1 to 87.30.207.25487.30.207.2554,094
11087.30.208.0/2087.30.208.1 to 87.30.223.25487.30.223.2554,094
11187.30.224.0/2087.30.224.1 to 87.30.239.25487.30.239.2554,094
11287.30.240.0/2087.30.240.1 to 87.30.255.25487.30.255.2554,094
11387.31.0.0/2087.31.0.1 to 87.31.15.25487.31.15.2554,094
11487.31.16.0/2087.31.16.1 to 87.31.31.25487.31.31.2554,094
11587.31.32.0/2087.31.32.1 to 87.31.47.25487.31.47.2554,094
11687.31.48.0/2087.31.48.1 to 87.31.63.25487.31.63.2554,094
11787.31.64.0/2087.31.64.1 to 87.31.79.25487.31.79.2554,094
11887.31.80.0/2087.31.80.1 to 87.31.95.25487.31.95.2554,094
11987.31.96.0/2087.31.96.1 to 87.31.111.25487.31.111.2554,094
12087.31.112.0/2087.31.112.1 to 87.31.127.25487.31.127.2554,094
12187.31.128.0/2087.31.128.1 to 87.31.143.25487.31.143.2554,094
12287.31.144.0/2087.31.144.1 to 87.31.159.25487.31.159.2554,094
12387.31.160.0/2087.31.160.1 to 87.31.175.25487.31.175.2554,094
12487.31.176.0/2087.31.176.1 to 87.31.191.25487.31.191.2554,094
12587.31.192.0/2087.31.192.1 to 87.31.207.25487.31.207.2554,094
12687.31.208.0/2087.31.208.1 to 87.31.223.25487.31.223.2554,094
12787.31.224.0/2087.31.224.1 to 87.31.239.25487.31.239.2554,094
12887.31.240.0/2087.31.240.1 to 87.31.255.25487.31.255.2554,094

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.