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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.

Network9.2.64.0/18
Usable hosts16,382
Subnet mask255.255.192.0
Addresses16,384
Network address
9.2.64.0
Broadcast address
9.2.127.255
First usable
9.2.64.1
Last usable
9.2.127.254
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 09024000 · Integer 151142400 to 151158783
Reverse DNS zones
64.2.9.in-addr.arpa
65.2.9.in-addr.arpa
66.2.9.in-addr.arpa
67.2.9.in-addr.arpa
68.2.9.in-addr.arpa
69.2.9.in-addr.arpa
70.2.9.in-addr.arpa
71.2.9.in-addr.arpa
72.2.9.in-addr.arpa
73.2.9.in-addr.arpa
74.2.9.in-addr.arpa
75.2.9.in-addr.arpa
76.2.9.in-addr.arpa
77.2.9.in-addr.arpa
78.2.9.in-addr.arpa
79.2.9.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
Address00001001.00000010.01000000.000000009.2.64.0
Subnet mask11111111.11111111.11000000.00000000255.255.192.0
Network00001001.00000010.01000000.000000009.2.64.0
Broadcast00001001.00000010.01111111.111111119.2.127.255
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)

9.2.64.0/18 makes 128 subnets of /25.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
19.2.64.0/259.2.64.1 to 9.2.64.1269.2.64.127126
29.2.64.128/259.2.64.129 to 9.2.64.2549.2.64.255126
39.2.65.0/259.2.65.1 to 9.2.65.1269.2.65.127126
49.2.65.128/259.2.65.129 to 9.2.65.2549.2.65.255126
59.2.66.0/259.2.66.1 to 9.2.66.1269.2.66.127126
69.2.66.128/259.2.66.129 to 9.2.66.2549.2.66.255126
79.2.67.0/259.2.67.1 to 9.2.67.1269.2.67.127126
89.2.67.128/259.2.67.129 to 9.2.67.2549.2.67.255126
99.2.68.0/259.2.68.1 to 9.2.68.1269.2.68.127126
109.2.68.128/259.2.68.129 to 9.2.68.2549.2.68.255126
119.2.69.0/259.2.69.1 to 9.2.69.1269.2.69.127126
129.2.69.128/259.2.69.129 to 9.2.69.2549.2.69.255126
139.2.70.0/259.2.70.1 to 9.2.70.1269.2.70.127126
149.2.70.128/259.2.70.129 to 9.2.70.2549.2.70.255126
159.2.71.0/259.2.71.1 to 9.2.71.1269.2.71.127126
169.2.71.128/259.2.71.129 to 9.2.71.2549.2.71.255126
179.2.72.0/259.2.72.1 to 9.2.72.1269.2.72.127126
189.2.72.128/259.2.72.129 to 9.2.72.2549.2.72.255126
199.2.73.0/259.2.73.1 to 9.2.73.1269.2.73.127126
209.2.73.128/259.2.73.129 to 9.2.73.2549.2.73.255126
219.2.74.0/259.2.74.1 to 9.2.74.1269.2.74.127126
229.2.74.128/259.2.74.129 to 9.2.74.2549.2.74.255126
239.2.75.0/259.2.75.1 to 9.2.75.1269.2.75.127126
249.2.75.128/259.2.75.129 to 9.2.75.2549.2.75.255126
259.2.76.0/259.2.76.1 to 9.2.76.1269.2.76.127126
269.2.76.128/259.2.76.129 to 9.2.76.2549.2.76.255126
279.2.77.0/259.2.77.1 to 9.2.77.1269.2.77.127126
289.2.77.128/259.2.77.129 to 9.2.77.2549.2.77.255126
299.2.78.0/259.2.78.1 to 9.2.78.1269.2.78.127126
309.2.78.128/259.2.78.129 to 9.2.78.2549.2.78.255126
319.2.79.0/259.2.79.1 to 9.2.79.1269.2.79.127126
329.2.79.128/259.2.79.129 to 9.2.79.2549.2.79.255126
339.2.80.0/259.2.80.1 to 9.2.80.1269.2.80.127126
349.2.80.128/259.2.80.129 to 9.2.80.2549.2.80.255126
359.2.81.0/259.2.81.1 to 9.2.81.1269.2.81.127126
369.2.81.128/259.2.81.129 to 9.2.81.2549.2.81.255126
379.2.82.0/259.2.82.1 to 9.2.82.1269.2.82.127126
389.2.82.128/259.2.82.129 to 9.2.82.2549.2.82.255126
399.2.83.0/259.2.83.1 to 9.2.83.1269.2.83.127126
409.2.83.128/259.2.83.129 to 9.2.83.2549.2.83.255126
419.2.84.0/259.2.84.1 to 9.2.84.1269.2.84.127126
429.2.84.128/259.2.84.129 to 9.2.84.2549.2.84.255126
439.2.85.0/259.2.85.1 to 9.2.85.1269.2.85.127126
449.2.85.128/259.2.85.129 to 9.2.85.2549.2.85.255126
459.2.86.0/259.2.86.1 to 9.2.86.1269.2.86.127126
469.2.86.128/259.2.86.129 to 9.2.86.2549.2.86.255126
479.2.87.0/259.2.87.1 to 9.2.87.1269.2.87.127126
489.2.87.128/259.2.87.129 to 9.2.87.2549.2.87.255126
499.2.88.0/259.2.88.1 to 9.2.88.1269.2.88.127126
509.2.88.128/259.2.88.129 to 9.2.88.2549.2.88.255126
519.2.89.0/259.2.89.1 to 9.2.89.1269.2.89.127126
529.2.89.128/259.2.89.129 to 9.2.89.2549.2.89.255126
539.2.90.0/259.2.90.1 to 9.2.90.1269.2.90.127126
549.2.90.128/259.2.90.129 to 9.2.90.2549.2.90.255126
559.2.91.0/259.2.91.1 to 9.2.91.1269.2.91.127126
569.2.91.128/259.2.91.129 to 9.2.91.2549.2.91.255126
579.2.92.0/259.2.92.1 to 9.2.92.1269.2.92.127126
589.2.92.128/259.2.92.129 to 9.2.92.2549.2.92.255126
599.2.93.0/259.2.93.1 to 9.2.93.1269.2.93.127126
609.2.93.128/259.2.93.129 to 9.2.93.2549.2.93.255126
619.2.94.0/259.2.94.1 to 9.2.94.1269.2.94.127126
629.2.94.128/259.2.94.129 to 9.2.94.2549.2.94.255126
639.2.95.0/259.2.95.1 to 9.2.95.1269.2.95.127126
649.2.95.128/259.2.95.129 to 9.2.95.2549.2.95.255126
659.2.96.0/259.2.96.1 to 9.2.96.1269.2.96.127126
669.2.96.128/259.2.96.129 to 9.2.96.2549.2.96.255126
679.2.97.0/259.2.97.1 to 9.2.97.1269.2.97.127126
689.2.97.128/259.2.97.129 to 9.2.97.2549.2.97.255126
699.2.98.0/259.2.98.1 to 9.2.98.1269.2.98.127126
709.2.98.128/259.2.98.129 to 9.2.98.2549.2.98.255126
719.2.99.0/259.2.99.1 to 9.2.99.1269.2.99.127126
729.2.99.128/259.2.99.129 to 9.2.99.2549.2.99.255126
739.2.100.0/259.2.100.1 to 9.2.100.1269.2.100.127126
749.2.100.128/259.2.100.129 to 9.2.100.2549.2.100.255126
759.2.101.0/259.2.101.1 to 9.2.101.1269.2.101.127126
769.2.101.128/259.2.101.129 to 9.2.101.2549.2.101.255126
779.2.102.0/259.2.102.1 to 9.2.102.1269.2.102.127126
789.2.102.128/259.2.102.129 to 9.2.102.2549.2.102.255126
799.2.103.0/259.2.103.1 to 9.2.103.1269.2.103.127126
809.2.103.128/259.2.103.129 to 9.2.103.2549.2.103.255126
819.2.104.0/259.2.104.1 to 9.2.104.1269.2.104.127126
829.2.104.128/259.2.104.129 to 9.2.104.2549.2.104.255126
839.2.105.0/259.2.105.1 to 9.2.105.1269.2.105.127126
849.2.105.128/259.2.105.129 to 9.2.105.2549.2.105.255126
859.2.106.0/259.2.106.1 to 9.2.106.1269.2.106.127126
869.2.106.128/259.2.106.129 to 9.2.106.2549.2.106.255126
879.2.107.0/259.2.107.1 to 9.2.107.1269.2.107.127126
889.2.107.128/259.2.107.129 to 9.2.107.2549.2.107.255126
899.2.108.0/259.2.108.1 to 9.2.108.1269.2.108.127126
909.2.108.128/259.2.108.129 to 9.2.108.2549.2.108.255126
919.2.109.0/259.2.109.1 to 9.2.109.1269.2.109.127126
929.2.109.128/259.2.109.129 to 9.2.109.2549.2.109.255126
939.2.110.0/259.2.110.1 to 9.2.110.1269.2.110.127126
949.2.110.128/259.2.110.129 to 9.2.110.2549.2.110.255126
959.2.111.0/259.2.111.1 to 9.2.111.1269.2.111.127126
969.2.111.128/259.2.111.129 to 9.2.111.2549.2.111.255126
979.2.112.0/259.2.112.1 to 9.2.112.1269.2.112.127126
989.2.112.128/259.2.112.129 to 9.2.112.2549.2.112.255126
999.2.113.0/259.2.113.1 to 9.2.113.1269.2.113.127126
1009.2.113.128/259.2.113.129 to 9.2.113.2549.2.113.255126
1019.2.114.0/259.2.114.1 to 9.2.114.1269.2.114.127126
1029.2.114.128/259.2.114.129 to 9.2.114.2549.2.114.255126
1039.2.115.0/259.2.115.1 to 9.2.115.1269.2.115.127126
1049.2.115.128/259.2.115.129 to 9.2.115.2549.2.115.255126
1059.2.116.0/259.2.116.1 to 9.2.116.1269.2.116.127126
1069.2.116.128/259.2.116.129 to 9.2.116.2549.2.116.255126
1079.2.117.0/259.2.117.1 to 9.2.117.1269.2.117.127126
1089.2.117.128/259.2.117.129 to 9.2.117.2549.2.117.255126
1099.2.118.0/259.2.118.1 to 9.2.118.1269.2.118.127126
1109.2.118.128/259.2.118.129 to 9.2.118.2549.2.118.255126
1119.2.119.0/259.2.119.1 to 9.2.119.1269.2.119.127126
1129.2.119.128/259.2.119.129 to 9.2.119.2549.2.119.255126
1139.2.120.0/259.2.120.1 to 9.2.120.1269.2.120.127126
1149.2.120.128/259.2.120.129 to 9.2.120.2549.2.120.255126
1159.2.121.0/259.2.121.1 to 9.2.121.1269.2.121.127126
1169.2.121.128/259.2.121.129 to 9.2.121.2549.2.121.255126
1179.2.122.0/259.2.122.1 to 9.2.122.1269.2.122.127126
1189.2.122.128/259.2.122.129 to 9.2.122.2549.2.122.255126
1199.2.123.0/259.2.123.1 to 9.2.123.1269.2.123.127126
1209.2.123.128/259.2.123.129 to 9.2.123.2549.2.123.255126
1219.2.124.0/259.2.124.1 to 9.2.124.1269.2.124.127126
1229.2.124.128/259.2.124.129 to 9.2.124.2549.2.124.255126
1239.2.125.0/259.2.125.1 to 9.2.125.1269.2.125.127126
1249.2.125.128/259.2.125.129 to 9.2.125.2549.2.125.255126
1259.2.126.0/259.2.126.1 to 9.2.126.1269.2.126.127126
1269.2.126.128/259.2.126.129 to 9.2.126.2549.2.126.255126
1279.2.127.0/259.2.127.1 to 9.2.127.1269.2.127.127126
1289.2.127.128/259.2.127.129 to 9.2.127.2549.2.127.255126

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.