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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.

Network5.0.0.0/11
Usable hosts2,097,150
Subnet mask255.224.0.0
Addresses2,097,152
Network address
5.0.0.0
Broadcast address
5.31.255.255
First usable
5.0.0.1
Last usable
5.31.255.254
Usable hosts
2,097,150 (2,097,152 less the network and broadcast addresses)
Subnet mask
255.224.0.0
Wildcard mask
0.31.255.255 (Cisco ACLs, OSPF)
Prefix length
/11
Type
Public public
Old class
A (default /8)
As numbers
Hex 05000000 · Integer 83886080 to 85983231
Reverse DNS zones
0.5.in-addr.arpa
1.5.in-addr.arpa
2.5.in-addr.arpa
3.5.in-addr.arpa
4.5.in-addr.arpa
5.5.in-addr.arpa
6.5.in-addr.arpa
7.5.in-addr.arpa
8.5.in-addr.arpa
9.5.in-addr.arpa
10.5.in-addr.arpa
11.5.in-addr.arpa
12.5.in-addr.arpa
13.5.in-addr.arpa
14.5.in-addr.arpa
15.5.in-addr.arpa
and 16 more
/11 is not on a 8-bit boundary, so it takes 32 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00000101.00000000.00000000.000000005.0.0.0
Subnet mask11111111.11100000.00000000.00000000255.224.0.0
Network00000101.00000000.00000000.000000005.0.0.0
Broadcast00000101.00011111.11111111.111111115.31.255.255
Split into smaller subnets/18
/12 (2)/13 (4)/14 (8)/15 (16)/16 (32)/17 (64)/18 (128)/19 (256)/20 (512)/21 (1,024)/22 (2,048)/23 (4,096)

5.0.0.0/11 makes 128 subnets of /18.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
15.0.0.0/185.0.0.1 to 5.0.63.2545.0.63.25516,382
25.0.64.0/185.0.64.1 to 5.0.127.2545.0.127.25516,382
35.0.128.0/185.0.128.1 to 5.0.191.2545.0.191.25516,382
45.0.192.0/185.0.192.1 to 5.0.255.2545.0.255.25516,382
55.1.0.0/185.1.0.1 to 5.1.63.2545.1.63.25516,382
65.1.64.0/185.1.64.1 to 5.1.127.2545.1.127.25516,382
75.1.128.0/185.1.128.1 to 5.1.191.2545.1.191.25516,382
85.1.192.0/185.1.192.1 to 5.1.255.2545.1.255.25516,382
95.2.0.0/185.2.0.1 to 5.2.63.2545.2.63.25516,382
105.2.64.0/185.2.64.1 to 5.2.127.2545.2.127.25516,382
115.2.128.0/185.2.128.1 to 5.2.191.2545.2.191.25516,382
125.2.192.0/185.2.192.1 to 5.2.255.2545.2.255.25516,382
135.3.0.0/185.3.0.1 to 5.3.63.2545.3.63.25516,382
145.3.64.0/185.3.64.1 to 5.3.127.2545.3.127.25516,382
155.3.128.0/185.3.128.1 to 5.3.191.2545.3.191.25516,382
165.3.192.0/185.3.192.1 to 5.3.255.2545.3.255.25516,382
175.4.0.0/185.4.0.1 to 5.4.63.2545.4.63.25516,382
185.4.64.0/185.4.64.1 to 5.4.127.2545.4.127.25516,382
195.4.128.0/185.4.128.1 to 5.4.191.2545.4.191.25516,382
205.4.192.0/185.4.192.1 to 5.4.255.2545.4.255.25516,382
215.5.0.0/185.5.0.1 to 5.5.63.2545.5.63.25516,382
225.5.64.0/185.5.64.1 to 5.5.127.2545.5.127.25516,382
235.5.128.0/185.5.128.1 to 5.5.191.2545.5.191.25516,382
245.5.192.0/185.5.192.1 to 5.5.255.2545.5.255.25516,382
255.6.0.0/185.6.0.1 to 5.6.63.2545.6.63.25516,382
265.6.64.0/185.6.64.1 to 5.6.127.2545.6.127.25516,382
275.6.128.0/185.6.128.1 to 5.6.191.2545.6.191.25516,382
285.6.192.0/185.6.192.1 to 5.6.255.2545.6.255.25516,382
295.7.0.0/185.7.0.1 to 5.7.63.2545.7.63.25516,382
305.7.64.0/185.7.64.1 to 5.7.127.2545.7.127.25516,382
315.7.128.0/185.7.128.1 to 5.7.191.2545.7.191.25516,382
325.7.192.0/185.7.192.1 to 5.7.255.2545.7.255.25516,382
335.8.0.0/185.8.0.1 to 5.8.63.2545.8.63.25516,382
345.8.64.0/185.8.64.1 to 5.8.127.2545.8.127.25516,382
355.8.128.0/185.8.128.1 to 5.8.191.2545.8.191.25516,382
365.8.192.0/185.8.192.1 to 5.8.255.2545.8.255.25516,382
375.9.0.0/185.9.0.1 to 5.9.63.2545.9.63.25516,382
385.9.64.0/185.9.64.1 to 5.9.127.2545.9.127.25516,382
395.9.128.0/185.9.128.1 to 5.9.191.2545.9.191.25516,382
405.9.192.0/185.9.192.1 to 5.9.255.2545.9.255.25516,382
415.10.0.0/185.10.0.1 to 5.10.63.2545.10.63.25516,382
425.10.64.0/185.10.64.1 to 5.10.127.2545.10.127.25516,382
435.10.128.0/185.10.128.1 to 5.10.191.2545.10.191.25516,382
445.10.192.0/185.10.192.1 to 5.10.255.2545.10.255.25516,382
455.11.0.0/185.11.0.1 to 5.11.63.2545.11.63.25516,382
465.11.64.0/185.11.64.1 to 5.11.127.2545.11.127.25516,382
475.11.128.0/185.11.128.1 to 5.11.191.2545.11.191.25516,382
485.11.192.0/185.11.192.1 to 5.11.255.2545.11.255.25516,382
495.12.0.0/185.12.0.1 to 5.12.63.2545.12.63.25516,382
505.12.64.0/185.12.64.1 to 5.12.127.2545.12.127.25516,382
515.12.128.0/185.12.128.1 to 5.12.191.2545.12.191.25516,382
525.12.192.0/185.12.192.1 to 5.12.255.2545.12.255.25516,382
535.13.0.0/185.13.0.1 to 5.13.63.2545.13.63.25516,382
545.13.64.0/185.13.64.1 to 5.13.127.2545.13.127.25516,382
555.13.128.0/185.13.128.1 to 5.13.191.2545.13.191.25516,382
565.13.192.0/185.13.192.1 to 5.13.255.2545.13.255.25516,382
575.14.0.0/185.14.0.1 to 5.14.63.2545.14.63.25516,382
585.14.64.0/185.14.64.1 to 5.14.127.2545.14.127.25516,382
595.14.128.0/185.14.128.1 to 5.14.191.2545.14.191.25516,382
605.14.192.0/185.14.192.1 to 5.14.255.2545.14.255.25516,382
615.15.0.0/185.15.0.1 to 5.15.63.2545.15.63.25516,382
625.15.64.0/185.15.64.1 to 5.15.127.2545.15.127.25516,382
635.15.128.0/185.15.128.1 to 5.15.191.2545.15.191.25516,382
645.15.192.0/185.15.192.1 to 5.15.255.2545.15.255.25516,382
655.16.0.0/185.16.0.1 to 5.16.63.2545.16.63.25516,382
665.16.64.0/185.16.64.1 to 5.16.127.2545.16.127.25516,382
675.16.128.0/185.16.128.1 to 5.16.191.2545.16.191.25516,382
685.16.192.0/185.16.192.1 to 5.16.255.2545.16.255.25516,382
695.17.0.0/185.17.0.1 to 5.17.63.2545.17.63.25516,382
705.17.64.0/185.17.64.1 to 5.17.127.2545.17.127.25516,382
715.17.128.0/185.17.128.1 to 5.17.191.2545.17.191.25516,382
725.17.192.0/185.17.192.1 to 5.17.255.2545.17.255.25516,382
735.18.0.0/185.18.0.1 to 5.18.63.2545.18.63.25516,382
745.18.64.0/185.18.64.1 to 5.18.127.2545.18.127.25516,382
755.18.128.0/185.18.128.1 to 5.18.191.2545.18.191.25516,382
765.18.192.0/185.18.192.1 to 5.18.255.2545.18.255.25516,382
775.19.0.0/185.19.0.1 to 5.19.63.2545.19.63.25516,382
785.19.64.0/185.19.64.1 to 5.19.127.2545.19.127.25516,382
795.19.128.0/185.19.128.1 to 5.19.191.2545.19.191.25516,382
805.19.192.0/185.19.192.1 to 5.19.255.2545.19.255.25516,382
815.20.0.0/185.20.0.1 to 5.20.63.2545.20.63.25516,382
825.20.64.0/185.20.64.1 to 5.20.127.2545.20.127.25516,382
835.20.128.0/185.20.128.1 to 5.20.191.2545.20.191.25516,382
845.20.192.0/185.20.192.1 to 5.20.255.2545.20.255.25516,382
855.21.0.0/185.21.0.1 to 5.21.63.2545.21.63.25516,382
865.21.64.0/185.21.64.1 to 5.21.127.2545.21.127.25516,382
875.21.128.0/185.21.128.1 to 5.21.191.2545.21.191.25516,382
885.21.192.0/185.21.192.1 to 5.21.255.2545.21.255.25516,382
895.22.0.0/185.22.0.1 to 5.22.63.2545.22.63.25516,382
905.22.64.0/185.22.64.1 to 5.22.127.2545.22.127.25516,382
915.22.128.0/185.22.128.1 to 5.22.191.2545.22.191.25516,382
925.22.192.0/185.22.192.1 to 5.22.255.2545.22.255.25516,382
935.23.0.0/185.23.0.1 to 5.23.63.2545.23.63.25516,382
945.23.64.0/185.23.64.1 to 5.23.127.2545.23.127.25516,382
955.23.128.0/185.23.128.1 to 5.23.191.2545.23.191.25516,382
965.23.192.0/185.23.192.1 to 5.23.255.2545.23.255.25516,382
975.24.0.0/185.24.0.1 to 5.24.63.2545.24.63.25516,382
985.24.64.0/185.24.64.1 to 5.24.127.2545.24.127.25516,382
995.24.128.0/185.24.128.1 to 5.24.191.2545.24.191.25516,382
1005.24.192.0/185.24.192.1 to 5.24.255.2545.24.255.25516,382
1015.25.0.0/185.25.0.1 to 5.25.63.2545.25.63.25516,382
1025.25.64.0/185.25.64.1 to 5.25.127.2545.25.127.25516,382
1035.25.128.0/185.25.128.1 to 5.25.191.2545.25.191.25516,382
1045.25.192.0/185.25.192.1 to 5.25.255.2545.25.255.25516,382
1055.26.0.0/185.26.0.1 to 5.26.63.2545.26.63.25516,382
1065.26.64.0/185.26.64.1 to 5.26.127.2545.26.127.25516,382
1075.26.128.0/185.26.128.1 to 5.26.191.2545.26.191.25516,382
1085.26.192.0/185.26.192.1 to 5.26.255.2545.26.255.25516,382
1095.27.0.0/185.27.0.1 to 5.27.63.2545.27.63.25516,382
1105.27.64.0/185.27.64.1 to 5.27.127.2545.27.127.25516,382
1115.27.128.0/185.27.128.1 to 5.27.191.2545.27.191.25516,382
1125.27.192.0/185.27.192.1 to 5.27.255.2545.27.255.25516,382
1135.28.0.0/185.28.0.1 to 5.28.63.2545.28.63.25516,382
1145.28.64.0/185.28.64.1 to 5.28.127.2545.28.127.25516,382
1155.28.128.0/185.28.128.1 to 5.28.191.2545.28.191.25516,382
1165.28.192.0/185.28.192.1 to 5.28.255.2545.28.255.25516,382
1175.29.0.0/185.29.0.1 to 5.29.63.2545.29.63.25516,382
1185.29.64.0/185.29.64.1 to 5.29.127.2545.29.127.25516,382
1195.29.128.0/185.29.128.1 to 5.29.191.2545.29.191.25516,382
1205.29.192.0/185.29.192.1 to 5.29.255.2545.29.255.25516,382
1215.30.0.0/185.30.0.1 to 5.30.63.2545.30.63.25516,382
1225.30.64.0/185.30.64.1 to 5.30.127.2545.30.127.25516,382
1235.30.128.0/185.30.128.1 to 5.30.191.2545.30.191.25516,382
1245.30.192.0/185.30.192.1 to 5.30.255.2545.30.255.25516,382
1255.31.0.0/185.31.0.1 to 5.31.63.2545.31.63.25516,382
1265.31.64.0/185.31.64.1 to 5.31.127.2545.31.127.25516,382
1275.31.128.0/185.31.128.1 to 5.31.191.2545.31.191.25516,382
1285.31.192.0/185.31.192.1 to 5.31.255.2545.31.255.25516,382

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.