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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.

Network5.96.176.0/20
Usable hosts4,094
Subnet mask255.255.240.0
Addresses4,096
Network address
5.96.176.0
Broadcast address
5.96.191.255
First usable
5.96.176.1
Last usable
5.96.191.254
Usable hosts
4,094 (4,096 less the network and broadcast addresses)
Subnet mask
255.255.240.0
Wildcard mask
0.0.15.255 (Cisco ACLs, OSPF)
Prefix length
/20
Type
Public public
Old class
A (default /8)
As numbers
Hex 0560B000 · Integer 90222592 to 90226687
Reverse DNS zones
176.96.5.in-addr.arpa
177.96.5.in-addr.arpa
178.96.5.in-addr.arpa
179.96.5.in-addr.arpa
180.96.5.in-addr.arpa
181.96.5.in-addr.arpa
182.96.5.in-addr.arpa
183.96.5.in-addr.arpa
184.96.5.in-addr.arpa
185.96.5.in-addr.arpa
186.96.5.in-addr.arpa
187.96.5.in-addr.arpa
188.96.5.in-addr.arpa
189.96.5.in-addr.arpa
190.96.5.in-addr.arpa
191.96.5.in-addr.arpa
/20 is not on a 8-bit boundary, so it takes 16 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00000101.01100000.10110000.000000005.96.176.0
Subnet mask11111111.11111111.11110000.00000000255.255.240.0
Network00000101.01100000.10110000.000000005.96.176.0
Broadcast00000101.01100000.10111111.111111115.96.191.255
Split into smaller subnets/27
/21 (2)/22 (4)/23 (8)/24 (16)/25 (32)/26 (64)/27 (128)/28 (256)/29 (512)/30 (1,024)/31 (2,048)/32 (4,096)

5.96.176.0/20 makes 128 subnets of /27.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
15.96.176.0/275.96.176.1 to 5.96.176.305.96.176.3130
25.96.176.32/275.96.176.33 to 5.96.176.625.96.176.6330
35.96.176.64/275.96.176.65 to 5.96.176.945.96.176.9530
45.96.176.96/275.96.176.97 to 5.96.176.1265.96.176.12730
55.96.176.128/275.96.176.129 to 5.96.176.1585.96.176.15930
65.96.176.160/275.96.176.161 to 5.96.176.1905.96.176.19130
75.96.176.192/275.96.176.193 to 5.96.176.2225.96.176.22330
85.96.176.224/275.96.176.225 to 5.96.176.2545.96.176.25530
95.96.177.0/275.96.177.1 to 5.96.177.305.96.177.3130
105.96.177.32/275.96.177.33 to 5.96.177.625.96.177.6330
115.96.177.64/275.96.177.65 to 5.96.177.945.96.177.9530
125.96.177.96/275.96.177.97 to 5.96.177.1265.96.177.12730
135.96.177.128/275.96.177.129 to 5.96.177.1585.96.177.15930
145.96.177.160/275.96.177.161 to 5.96.177.1905.96.177.19130
155.96.177.192/275.96.177.193 to 5.96.177.2225.96.177.22330
165.96.177.224/275.96.177.225 to 5.96.177.2545.96.177.25530
175.96.178.0/275.96.178.1 to 5.96.178.305.96.178.3130
185.96.178.32/275.96.178.33 to 5.96.178.625.96.178.6330
195.96.178.64/275.96.178.65 to 5.96.178.945.96.178.9530
205.96.178.96/275.96.178.97 to 5.96.178.1265.96.178.12730
215.96.178.128/275.96.178.129 to 5.96.178.1585.96.178.15930
225.96.178.160/275.96.178.161 to 5.96.178.1905.96.178.19130
235.96.178.192/275.96.178.193 to 5.96.178.2225.96.178.22330
245.96.178.224/275.96.178.225 to 5.96.178.2545.96.178.25530
255.96.179.0/275.96.179.1 to 5.96.179.305.96.179.3130
265.96.179.32/275.96.179.33 to 5.96.179.625.96.179.6330
275.96.179.64/275.96.179.65 to 5.96.179.945.96.179.9530
285.96.179.96/275.96.179.97 to 5.96.179.1265.96.179.12730
295.96.179.128/275.96.179.129 to 5.96.179.1585.96.179.15930
305.96.179.160/275.96.179.161 to 5.96.179.1905.96.179.19130
315.96.179.192/275.96.179.193 to 5.96.179.2225.96.179.22330
325.96.179.224/275.96.179.225 to 5.96.179.2545.96.179.25530
335.96.180.0/275.96.180.1 to 5.96.180.305.96.180.3130
345.96.180.32/275.96.180.33 to 5.96.180.625.96.180.6330
355.96.180.64/275.96.180.65 to 5.96.180.945.96.180.9530
365.96.180.96/275.96.180.97 to 5.96.180.1265.96.180.12730
375.96.180.128/275.96.180.129 to 5.96.180.1585.96.180.15930
385.96.180.160/275.96.180.161 to 5.96.180.1905.96.180.19130
395.96.180.192/275.96.180.193 to 5.96.180.2225.96.180.22330
405.96.180.224/275.96.180.225 to 5.96.180.2545.96.180.25530
415.96.181.0/275.96.181.1 to 5.96.181.305.96.181.3130
425.96.181.32/275.96.181.33 to 5.96.181.625.96.181.6330
435.96.181.64/275.96.181.65 to 5.96.181.945.96.181.9530
445.96.181.96/275.96.181.97 to 5.96.181.1265.96.181.12730
455.96.181.128/275.96.181.129 to 5.96.181.1585.96.181.15930
465.96.181.160/275.96.181.161 to 5.96.181.1905.96.181.19130
475.96.181.192/275.96.181.193 to 5.96.181.2225.96.181.22330
485.96.181.224/275.96.181.225 to 5.96.181.2545.96.181.25530
495.96.182.0/275.96.182.1 to 5.96.182.305.96.182.3130
505.96.182.32/275.96.182.33 to 5.96.182.625.96.182.6330
515.96.182.64/275.96.182.65 to 5.96.182.945.96.182.9530
525.96.182.96/275.96.182.97 to 5.96.182.1265.96.182.12730
535.96.182.128/275.96.182.129 to 5.96.182.1585.96.182.15930
545.96.182.160/275.96.182.161 to 5.96.182.1905.96.182.19130
555.96.182.192/275.96.182.193 to 5.96.182.2225.96.182.22330
565.96.182.224/275.96.182.225 to 5.96.182.2545.96.182.25530
575.96.183.0/275.96.183.1 to 5.96.183.305.96.183.3130
585.96.183.32/275.96.183.33 to 5.96.183.625.96.183.6330
595.96.183.64/275.96.183.65 to 5.96.183.945.96.183.9530
605.96.183.96/275.96.183.97 to 5.96.183.1265.96.183.12730
615.96.183.128/275.96.183.129 to 5.96.183.1585.96.183.15930
625.96.183.160/275.96.183.161 to 5.96.183.1905.96.183.19130
635.96.183.192/275.96.183.193 to 5.96.183.2225.96.183.22330
645.96.183.224/275.96.183.225 to 5.96.183.2545.96.183.25530
655.96.184.0/275.96.184.1 to 5.96.184.305.96.184.3130
665.96.184.32/275.96.184.33 to 5.96.184.625.96.184.6330
675.96.184.64/275.96.184.65 to 5.96.184.945.96.184.9530
685.96.184.96/275.96.184.97 to 5.96.184.1265.96.184.12730
695.96.184.128/275.96.184.129 to 5.96.184.1585.96.184.15930
705.96.184.160/275.96.184.161 to 5.96.184.1905.96.184.19130
715.96.184.192/275.96.184.193 to 5.96.184.2225.96.184.22330
725.96.184.224/275.96.184.225 to 5.96.184.2545.96.184.25530
735.96.185.0/275.96.185.1 to 5.96.185.305.96.185.3130
745.96.185.32/275.96.185.33 to 5.96.185.625.96.185.6330
755.96.185.64/275.96.185.65 to 5.96.185.945.96.185.9530
765.96.185.96/275.96.185.97 to 5.96.185.1265.96.185.12730
775.96.185.128/275.96.185.129 to 5.96.185.1585.96.185.15930
785.96.185.160/275.96.185.161 to 5.96.185.1905.96.185.19130
795.96.185.192/275.96.185.193 to 5.96.185.2225.96.185.22330
805.96.185.224/275.96.185.225 to 5.96.185.2545.96.185.25530
815.96.186.0/275.96.186.1 to 5.96.186.305.96.186.3130
825.96.186.32/275.96.186.33 to 5.96.186.625.96.186.6330
835.96.186.64/275.96.186.65 to 5.96.186.945.96.186.9530
845.96.186.96/275.96.186.97 to 5.96.186.1265.96.186.12730
855.96.186.128/275.96.186.129 to 5.96.186.1585.96.186.15930
865.96.186.160/275.96.186.161 to 5.96.186.1905.96.186.19130
875.96.186.192/275.96.186.193 to 5.96.186.2225.96.186.22330
885.96.186.224/275.96.186.225 to 5.96.186.2545.96.186.25530
895.96.187.0/275.96.187.1 to 5.96.187.305.96.187.3130
905.96.187.32/275.96.187.33 to 5.96.187.625.96.187.6330
915.96.187.64/275.96.187.65 to 5.96.187.945.96.187.9530
925.96.187.96/275.96.187.97 to 5.96.187.1265.96.187.12730
935.96.187.128/275.96.187.129 to 5.96.187.1585.96.187.15930
945.96.187.160/275.96.187.161 to 5.96.187.1905.96.187.19130
955.96.187.192/275.96.187.193 to 5.96.187.2225.96.187.22330
965.96.187.224/275.96.187.225 to 5.96.187.2545.96.187.25530
975.96.188.0/275.96.188.1 to 5.96.188.305.96.188.3130
985.96.188.32/275.96.188.33 to 5.96.188.625.96.188.6330
995.96.188.64/275.96.188.65 to 5.96.188.945.96.188.9530
1005.96.188.96/275.96.188.97 to 5.96.188.1265.96.188.12730
1015.96.188.128/275.96.188.129 to 5.96.188.1585.96.188.15930
1025.96.188.160/275.96.188.161 to 5.96.188.1905.96.188.19130
1035.96.188.192/275.96.188.193 to 5.96.188.2225.96.188.22330
1045.96.188.224/275.96.188.225 to 5.96.188.2545.96.188.25530
1055.96.189.0/275.96.189.1 to 5.96.189.305.96.189.3130
1065.96.189.32/275.96.189.33 to 5.96.189.625.96.189.6330
1075.96.189.64/275.96.189.65 to 5.96.189.945.96.189.9530
1085.96.189.96/275.96.189.97 to 5.96.189.1265.96.189.12730
1095.96.189.128/275.96.189.129 to 5.96.189.1585.96.189.15930
1105.96.189.160/275.96.189.161 to 5.96.189.1905.96.189.19130
1115.96.189.192/275.96.189.193 to 5.96.189.2225.96.189.22330
1125.96.189.224/275.96.189.225 to 5.96.189.2545.96.189.25530
1135.96.190.0/275.96.190.1 to 5.96.190.305.96.190.3130
1145.96.190.32/275.96.190.33 to 5.96.190.625.96.190.6330
1155.96.190.64/275.96.190.65 to 5.96.190.945.96.190.9530
1165.96.190.96/275.96.190.97 to 5.96.190.1265.96.190.12730
1175.96.190.128/275.96.190.129 to 5.96.190.1585.96.190.15930
1185.96.190.160/275.96.190.161 to 5.96.190.1905.96.190.19130
1195.96.190.192/275.96.190.193 to 5.96.190.2225.96.190.22330
1205.96.190.224/275.96.190.225 to 5.96.190.2545.96.190.25530
1215.96.191.0/275.96.191.1 to 5.96.191.305.96.191.3130
1225.96.191.32/275.96.191.33 to 5.96.191.625.96.191.6330
1235.96.191.64/275.96.191.65 to 5.96.191.945.96.191.9530
1245.96.191.96/275.96.191.97 to 5.96.191.1265.96.191.12730
1255.96.191.128/275.96.191.129 to 5.96.191.1585.96.191.15930
1265.96.191.160/275.96.191.161 to 5.96.191.1905.96.191.19130
1275.96.191.192/275.96.191.193 to 5.96.191.2225.96.191.22330
1285.96.191.224/275.96.191.225 to 5.96.191.2545.96.191.25530

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.