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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.

Network45.56.0.0/13
Usable hosts524,286
Subnet mask255.248.0.0
Addresses524,288
Network address
45.56.0.0
Broadcast address
45.63.255.255
First usable
45.56.0.1
Last usable
45.63.255.254
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 2D380000 · Integer 758644736 to 759169023
Reverse DNS zones
56.45.in-addr.arpa
57.45.in-addr.arpa
58.45.in-addr.arpa
59.45.in-addr.arpa
60.45.in-addr.arpa
61.45.in-addr.arpa
62.45.in-addr.arpa
63.45.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
Address00101101.00111000.00000000.0000000045.56.0.0
Subnet mask11111111.11111000.00000000.00000000255.248.0.0
Network00101101.00111000.00000000.0000000045.56.0.0
Broadcast00101101.00111111.11111111.1111111145.63.255.255
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)

45.56.0.0/13 makes 128 subnets of /20.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
145.56.0.0/2045.56.0.1 to 45.56.15.25445.56.15.2554,094
245.56.16.0/2045.56.16.1 to 45.56.31.25445.56.31.2554,094
345.56.32.0/2045.56.32.1 to 45.56.47.25445.56.47.2554,094
445.56.48.0/2045.56.48.1 to 45.56.63.25445.56.63.2554,094
545.56.64.0/2045.56.64.1 to 45.56.79.25445.56.79.2554,094
645.56.80.0/2045.56.80.1 to 45.56.95.25445.56.95.2554,094
745.56.96.0/2045.56.96.1 to 45.56.111.25445.56.111.2554,094
845.56.112.0/2045.56.112.1 to 45.56.127.25445.56.127.2554,094
945.56.128.0/2045.56.128.1 to 45.56.143.25445.56.143.2554,094
1045.56.144.0/2045.56.144.1 to 45.56.159.25445.56.159.2554,094
1145.56.160.0/2045.56.160.1 to 45.56.175.25445.56.175.2554,094
1245.56.176.0/2045.56.176.1 to 45.56.191.25445.56.191.2554,094
1345.56.192.0/2045.56.192.1 to 45.56.207.25445.56.207.2554,094
1445.56.208.0/2045.56.208.1 to 45.56.223.25445.56.223.2554,094
1545.56.224.0/2045.56.224.1 to 45.56.239.25445.56.239.2554,094
1645.56.240.0/2045.56.240.1 to 45.56.255.25445.56.255.2554,094
1745.57.0.0/2045.57.0.1 to 45.57.15.25445.57.15.2554,094
1845.57.16.0/2045.57.16.1 to 45.57.31.25445.57.31.2554,094
1945.57.32.0/2045.57.32.1 to 45.57.47.25445.57.47.2554,094
2045.57.48.0/2045.57.48.1 to 45.57.63.25445.57.63.2554,094
2145.57.64.0/2045.57.64.1 to 45.57.79.25445.57.79.2554,094
2245.57.80.0/2045.57.80.1 to 45.57.95.25445.57.95.2554,094
2345.57.96.0/2045.57.96.1 to 45.57.111.25445.57.111.2554,094
2445.57.112.0/2045.57.112.1 to 45.57.127.25445.57.127.2554,094
2545.57.128.0/2045.57.128.1 to 45.57.143.25445.57.143.2554,094
2645.57.144.0/2045.57.144.1 to 45.57.159.25445.57.159.2554,094
2745.57.160.0/2045.57.160.1 to 45.57.175.25445.57.175.2554,094
2845.57.176.0/2045.57.176.1 to 45.57.191.25445.57.191.2554,094
2945.57.192.0/2045.57.192.1 to 45.57.207.25445.57.207.2554,094
3045.57.208.0/2045.57.208.1 to 45.57.223.25445.57.223.2554,094
3145.57.224.0/2045.57.224.1 to 45.57.239.25445.57.239.2554,094
3245.57.240.0/2045.57.240.1 to 45.57.255.25445.57.255.2554,094
3345.58.0.0/2045.58.0.1 to 45.58.15.25445.58.15.2554,094
3445.58.16.0/2045.58.16.1 to 45.58.31.25445.58.31.2554,094
3545.58.32.0/2045.58.32.1 to 45.58.47.25445.58.47.2554,094
3645.58.48.0/2045.58.48.1 to 45.58.63.25445.58.63.2554,094
3745.58.64.0/2045.58.64.1 to 45.58.79.25445.58.79.2554,094
3845.58.80.0/2045.58.80.1 to 45.58.95.25445.58.95.2554,094
3945.58.96.0/2045.58.96.1 to 45.58.111.25445.58.111.2554,094
4045.58.112.0/2045.58.112.1 to 45.58.127.25445.58.127.2554,094
4145.58.128.0/2045.58.128.1 to 45.58.143.25445.58.143.2554,094
4245.58.144.0/2045.58.144.1 to 45.58.159.25445.58.159.2554,094
4345.58.160.0/2045.58.160.1 to 45.58.175.25445.58.175.2554,094
4445.58.176.0/2045.58.176.1 to 45.58.191.25445.58.191.2554,094
4545.58.192.0/2045.58.192.1 to 45.58.207.25445.58.207.2554,094
4645.58.208.0/2045.58.208.1 to 45.58.223.25445.58.223.2554,094
4745.58.224.0/2045.58.224.1 to 45.58.239.25445.58.239.2554,094
4845.58.240.0/2045.58.240.1 to 45.58.255.25445.58.255.2554,094
4945.59.0.0/2045.59.0.1 to 45.59.15.25445.59.15.2554,094
5045.59.16.0/2045.59.16.1 to 45.59.31.25445.59.31.2554,094
5145.59.32.0/2045.59.32.1 to 45.59.47.25445.59.47.2554,094
5245.59.48.0/2045.59.48.1 to 45.59.63.25445.59.63.2554,094
5345.59.64.0/2045.59.64.1 to 45.59.79.25445.59.79.2554,094
5445.59.80.0/2045.59.80.1 to 45.59.95.25445.59.95.2554,094
5545.59.96.0/2045.59.96.1 to 45.59.111.25445.59.111.2554,094
5645.59.112.0/2045.59.112.1 to 45.59.127.25445.59.127.2554,094
5745.59.128.0/2045.59.128.1 to 45.59.143.25445.59.143.2554,094
5845.59.144.0/2045.59.144.1 to 45.59.159.25445.59.159.2554,094
5945.59.160.0/2045.59.160.1 to 45.59.175.25445.59.175.2554,094
6045.59.176.0/2045.59.176.1 to 45.59.191.25445.59.191.2554,094
6145.59.192.0/2045.59.192.1 to 45.59.207.25445.59.207.2554,094
6245.59.208.0/2045.59.208.1 to 45.59.223.25445.59.223.2554,094
6345.59.224.0/2045.59.224.1 to 45.59.239.25445.59.239.2554,094
6445.59.240.0/2045.59.240.1 to 45.59.255.25445.59.255.2554,094
6545.60.0.0/2045.60.0.1 to 45.60.15.25445.60.15.2554,094
6645.60.16.0/2045.60.16.1 to 45.60.31.25445.60.31.2554,094
6745.60.32.0/2045.60.32.1 to 45.60.47.25445.60.47.2554,094
6845.60.48.0/2045.60.48.1 to 45.60.63.25445.60.63.2554,094
6945.60.64.0/2045.60.64.1 to 45.60.79.25445.60.79.2554,094
7045.60.80.0/2045.60.80.1 to 45.60.95.25445.60.95.2554,094
7145.60.96.0/2045.60.96.1 to 45.60.111.25445.60.111.2554,094
7245.60.112.0/2045.60.112.1 to 45.60.127.25445.60.127.2554,094
7345.60.128.0/2045.60.128.1 to 45.60.143.25445.60.143.2554,094
7445.60.144.0/2045.60.144.1 to 45.60.159.25445.60.159.2554,094
7545.60.160.0/2045.60.160.1 to 45.60.175.25445.60.175.2554,094
7645.60.176.0/2045.60.176.1 to 45.60.191.25445.60.191.2554,094
7745.60.192.0/2045.60.192.1 to 45.60.207.25445.60.207.2554,094
7845.60.208.0/2045.60.208.1 to 45.60.223.25445.60.223.2554,094
7945.60.224.0/2045.60.224.1 to 45.60.239.25445.60.239.2554,094
8045.60.240.0/2045.60.240.1 to 45.60.255.25445.60.255.2554,094
8145.61.0.0/2045.61.0.1 to 45.61.15.25445.61.15.2554,094
8245.61.16.0/2045.61.16.1 to 45.61.31.25445.61.31.2554,094
8345.61.32.0/2045.61.32.1 to 45.61.47.25445.61.47.2554,094
8445.61.48.0/2045.61.48.1 to 45.61.63.25445.61.63.2554,094
8545.61.64.0/2045.61.64.1 to 45.61.79.25445.61.79.2554,094
8645.61.80.0/2045.61.80.1 to 45.61.95.25445.61.95.2554,094
8745.61.96.0/2045.61.96.1 to 45.61.111.25445.61.111.2554,094
8845.61.112.0/2045.61.112.1 to 45.61.127.25445.61.127.2554,094
8945.61.128.0/2045.61.128.1 to 45.61.143.25445.61.143.2554,094
9045.61.144.0/2045.61.144.1 to 45.61.159.25445.61.159.2554,094
9145.61.160.0/2045.61.160.1 to 45.61.175.25445.61.175.2554,094
9245.61.176.0/2045.61.176.1 to 45.61.191.25445.61.191.2554,094
9345.61.192.0/2045.61.192.1 to 45.61.207.25445.61.207.2554,094
9445.61.208.0/2045.61.208.1 to 45.61.223.25445.61.223.2554,094
9545.61.224.0/2045.61.224.1 to 45.61.239.25445.61.239.2554,094
9645.61.240.0/2045.61.240.1 to 45.61.255.25445.61.255.2554,094
9745.62.0.0/2045.62.0.1 to 45.62.15.25445.62.15.2554,094
9845.62.16.0/2045.62.16.1 to 45.62.31.25445.62.31.2554,094
9945.62.32.0/2045.62.32.1 to 45.62.47.25445.62.47.2554,094
10045.62.48.0/2045.62.48.1 to 45.62.63.25445.62.63.2554,094
10145.62.64.0/2045.62.64.1 to 45.62.79.25445.62.79.2554,094
10245.62.80.0/2045.62.80.1 to 45.62.95.25445.62.95.2554,094
10345.62.96.0/2045.62.96.1 to 45.62.111.25445.62.111.2554,094
10445.62.112.0/2045.62.112.1 to 45.62.127.25445.62.127.2554,094
10545.62.128.0/2045.62.128.1 to 45.62.143.25445.62.143.2554,094
10645.62.144.0/2045.62.144.1 to 45.62.159.25445.62.159.2554,094
10745.62.160.0/2045.62.160.1 to 45.62.175.25445.62.175.2554,094
10845.62.176.0/2045.62.176.1 to 45.62.191.25445.62.191.2554,094
10945.62.192.0/2045.62.192.1 to 45.62.207.25445.62.207.2554,094
11045.62.208.0/2045.62.208.1 to 45.62.223.25445.62.223.2554,094
11145.62.224.0/2045.62.224.1 to 45.62.239.25445.62.239.2554,094
11245.62.240.0/2045.62.240.1 to 45.62.255.25445.62.255.2554,094
11345.63.0.0/2045.63.0.1 to 45.63.15.25445.63.15.2554,094
11445.63.16.0/2045.63.16.1 to 45.63.31.25445.63.31.2554,094
11545.63.32.0/2045.63.32.1 to 45.63.47.25445.63.47.2554,094
11645.63.48.0/2045.63.48.1 to 45.63.63.25445.63.63.2554,094
11745.63.64.0/2045.63.64.1 to 45.63.79.25445.63.79.2554,094
11845.63.80.0/2045.63.80.1 to 45.63.95.25445.63.95.2554,094
11945.63.96.0/2045.63.96.1 to 45.63.111.25445.63.111.2554,094
12045.63.112.0/2045.63.112.1 to 45.63.127.25445.63.127.2554,094
12145.63.128.0/2045.63.128.1 to 45.63.143.25445.63.143.2554,094
12245.63.144.0/2045.63.144.1 to 45.63.159.25445.63.159.2554,094
12345.63.160.0/2045.63.160.1 to 45.63.175.25445.63.175.2554,094
12445.63.176.0/2045.63.176.1 to 45.63.191.25445.63.191.2554,094
12545.63.192.0/2045.63.192.1 to 45.63.207.25445.63.207.2554,094
12645.63.208.0/2045.63.208.1 to 45.63.223.25445.63.223.2554,094
12745.63.224.0/2045.63.224.1 to 45.63.239.25445.63.239.2554,094
12845.63.240.0/2045.63.240.1 to 45.63.255.25445.63.255.2554,094

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.