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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.

Network29.166.32.0/19
Usable hosts8,190
Subnet mask255.255.224.0
Addresses8,192
Network address
29.166.32.0
Broadcast address
29.166.63.255
First usable
29.166.32.1
Last usable
29.166.63.254
Usable hosts
8,190 (8,192 less the network and broadcast addresses)
Subnet mask
255.255.224.0
Wildcard mask
0.0.31.255 (Cisco ACLs, OSPF)
Prefix length
/19
Type
Public public
Old class
A (default /8)
As numbers
Hex 1DA62000 · Integer 497426432 to 497434623
Reverse DNS zones
32.166.29.in-addr.arpa
33.166.29.in-addr.arpa
34.166.29.in-addr.arpa
35.166.29.in-addr.arpa
36.166.29.in-addr.arpa
37.166.29.in-addr.arpa
38.166.29.in-addr.arpa
39.166.29.in-addr.arpa
40.166.29.in-addr.arpa
41.166.29.in-addr.arpa
42.166.29.in-addr.arpa
43.166.29.in-addr.arpa
44.166.29.in-addr.arpa
45.166.29.in-addr.arpa
46.166.29.in-addr.arpa
47.166.29.in-addr.arpa
and 16 more
/19 is not on a 8-bit boundary, so it takes 32 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00011101.10100110.00100000.0000000029.166.32.0
Subnet mask11111111.11111111.11100000.00000000255.255.224.0
Network00011101.10100110.00100000.0000000029.166.32.0
Broadcast00011101.10100110.00111111.1111111129.166.63.255
Split into smaller subnets/26
/20 (2)/21 (4)/22 (8)/23 (16)/24 (32)/25 (64)/26 (128)/27 (256)/28 (512)/29 (1,024)/30 (2,048)/31 (4,096)

29.166.32.0/19 makes 128 subnets of /26.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
129.166.32.0/2629.166.32.1 to 29.166.32.6229.166.32.6362
229.166.32.64/2629.166.32.65 to 29.166.32.12629.166.32.12762
329.166.32.128/2629.166.32.129 to 29.166.32.19029.166.32.19162
429.166.32.192/2629.166.32.193 to 29.166.32.25429.166.32.25562
529.166.33.0/2629.166.33.1 to 29.166.33.6229.166.33.6362
629.166.33.64/2629.166.33.65 to 29.166.33.12629.166.33.12762
729.166.33.128/2629.166.33.129 to 29.166.33.19029.166.33.19162
829.166.33.192/2629.166.33.193 to 29.166.33.25429.166.33.25562
929.166.34.0/2629.166.34.1 to 29.166.34.6229.166.34.6362
1029.166.34.64/2629.166.34.65 to 29.166.34.12629.166.34.12762
1129.166.34.128/2629.166.34.129 to 29.166.34.19029.166.34.19162
1229.166.34.192/2629.166.34.193 to 29.166.34.25429.166.34.25562
1329.166.35.0/2629.166.35.1 to 29.166.35.6229.166.35.6362
1429.166.35.64/2629.166.35.65 to 29.166.35.12629.166.35.12762
1529.166.35.128/2629.166.35.129 to 29.166.35.19029.166.35.19162
1629.166.35.192/2629.166.35.193 to 29.166.35.25429.166.35.25562
1729.166.36.0/2629.166.36.1 to 29.166.36.6229.166.36.6362
1829.166.36.64/2629.166.36.65 to 29.166.36.12629.166.36.12762
1929.166.36.128/2629.166.36.129 to 29.166.36.19029.166.36.19162
2029.166.36.192/2629.166.36.193 to 29.166.36.25429.166.36.25562
2129.166.37.0/2629.166.37.1 to 29.166.37.6229.166.37.6362
2229.166.37.64/2629.166.37.65 to 29.166.37.12629.166.37.12762
2329.166.37.128/2629.166.37.129 to 29.166.37.19029.166.37.19162
2429.166.37.192/2629.166.37.193 to 29.166.37.25429.166.37.25562
2529.166.38.0/2629.166.38.1 to 29.166.38.6229.166.38.6362
2629.166.38.64/2629.166.38.65 to 29.166.38.12629.166.38.12762
2729.166.38.128/2629.166.38.129 to 29.166.38.19029.166.38.19162
2829.166.38.192/2629.166.38.193 to 29.166.38.25429.166.38.25562
2929.166.39.0/2629.166.39.1 to 29.166.39.6229.166.39.6362
3029.166.39.64/2629.166.39.65 to 29.166.39.12629.166.39.12762
3129.166.39.128/2629.166.39.129 to 29.166.39.19029.166.39.19162
3229.166.39.192/2629.166.39.193 to 29.166.39.25429.166.39.25562
3329.166.40.0/2629.166.40.1 to 29.166.40.6229.166.40.6362
3429.166.40.64/2629.166.40.65 to 29.166.40.12629.166.40.12762
3529.166.40.128/2629.166.40.129 to 29.166.40.19029.166.40.19162
3629.166.40.192/2629.166.40.193 to 29.166.40.25429.166.40.25562
3729.166.41.0/2629.166.41.1 to 29.166.41.6229.166.41.6362
3829.166.41.64/2629.166.41.65 to 29.166.41.12629.166.41.12762
3929.166.41.128/2629.166.41.129 to 29.166.41.19029.166.41.19162
4029.166.41.192/2629.166.41.193 to 29.166.41.25429.166.41.25562
4129.166.42.0/2629.166.42.1 to 29.166.42.6229.166.42.6362
4229.166.42.64/2629.166.42.65 to 29.166.42.12629.166.42.12762
4329.166.42.128/2629.166.42.129 to 29.166.42.19029.166.42.19162
4429.166.42.192/2629.166.42.193 to 29.166.42.25429.166.42.25562
4529.166.43.0/2629.166.43.1 to 29.166.43.6229.166.43.6362
4629.166.43.64/2629.166.43.65 to 29.166.43.12629.166.43.12762
4729.166.43.128/2629.166.43.129 to 29.166.43.19029.166.43.19162
4829.166.43.192/2629.166.43.193 to 29.166.43.25429.166.43.25562
4929.166.44.0/2629.166.44.1 to 29.166.44.6229.166.44.6362
5029.166.44.64/2629.166.44.65 to 29.166.44.12629.166.44.12762
5129.166.44.128/2629.166.44.129 to 29.166.44.19029.166.44.19162
5229.166.44.192/2629.166.44.193 to 29.166.44.25429.166.44.25562
5329.166.45.0/2629.166.45.1 to 29.166.45.6229.166.45.6362
5429.166.45.64/2629.166.45.65 to 29.166.45.12629.166.45.12762
5529.166.45.128/2629.166.45.129 to 29.166.45.19029.166.45.19162
5629.166.45.192/2629.166.45.193 to 29.166.45.25429.166.45.25562
5729.166.46.0/2629.166.46.1 to 29.166.46.6229.166.46.6362
5829.166.46.64/2629.166.46.65 to 29.166.46.12629.166.46.12762
5929.166.46.128/2629.166.46.129 to 29.166.46.19029.166.46.19162
6029.166.46.192/2629.166.46.193 to 29.166.46.25429.166.46.25562
6129.166.47.0/2629.166.47.1 to 29.166.47.6229.166.47.6362
6229.166.47.64/2629.166.47.65 to 29.166.47.12629.166.47.12762
6329.166.47.128/2629.166.47.129 to 29.166.47.19029.166.47.19162
6429.166.47.192/2629.166.47.193 to 29.166.47.25429.166.47.25562
6529.166.48.0/2629.166.48.1 to 29.166.48.6229.166.48.6362
6629.166.48.64/2629.166.48.65 to 29.166.48.12629.166.48.12762
6729.166.48.128/2629.166.48.129 to 29.166.48.19029.166.48.19162
6829.166.48.192/2629.166.48.193 to 29.166.48.25429.166.48.25562
6929.166.49.0/2629.166.49.1 to 29.166.49.6229.166.49.6362
7029.166.49.64/2629.166.49.65 to 29.166.49.12629.166.49.12762
7129.166.49.128/2629.166.49.129 to 29.166.49.19029.166.49.19162
7229.166.49.192/2629.166.49.193 to 29.166.49.25429.166.49.25562
7329.166.50.0/2629.166.50.1 to 29.166.50.6229.166.50.6362
7429.166.50.64/2629.166.50.65 to 29.166.50.12629.166.50.12762
7529.166.50.128/2629.166.50.129 to 29.166.50.19029.166.50.19162
7629.166.50.192/2629.166.50.193 to 29.166.50.25429.166.50.25562
7729.166.51.0/2629.166.51.1 to 29.166.51.6229.166.51.6362
7829.166.51.64/2629.166.51.65 to 29.166.51.12629.166.51.12762
7929.166.51.128/2629.166.51.129 to 29.166.51.19029.166.51.19162
8029.166.51.192/2629.166.51.193 to 29.166.51.25429.166.51.25562
8129.166.52.0/2629.166.52.1 to 29.166.52.6229.166.52.6362
8229.166.52.64/2629.166.52.65 to 29.166.52.12629.166.52.12762
8329.166.52.128/2629.166.52.129 to 29.166.52.19029.166.52.19162
8429.166.52.192/2629.166.52.193 to 29.166.52.25429.166.52.25562
8529.166.53.0/2629.166.53.1 to 29.166.53.6229.166.53.6362
8629.166.53.64/2629.166.53.65 to 29.166.53.12629.166.53.12762
8729.166.53.128/2629.166.53.129 to 29.166.53.19029.166.53.19162
8829.166.53.192/2629.166.53.193 to 29.166.53.25429.166.53.25562
8929.166.54.0/2629.166.54.1 to 29.166.54.6229.166.54.6362
9029.166.54.64/2629.166.54.65 to 29.166.54.12629.166.54.12762
9129.166.54.128/2629.166.54.129 to 29.166.54.19029.166.54.19162
9229.166.54.192/2629.166.54.193 to 29.166.54.25429.166.54.25562
9329.166.55.0/2629.166.55.1 to 29.166.55.6229.166.55.6362
9429.166.55.64/2629.166.55.65 to 29.166.55.12629.166.55.12762
9529.166.55.128/2629.166.55.129 to 29.166.55.19029.166.55.19162
9629.166.55.192/2629.166.55.193 to 29.166.55.25429.166.55.25562
9729.166.56.0/2629.166.56.1 to 29.166.56.6229.166.56.6362
9829.166.56.64/2629.166.56.65 to 29.166.56.12629.166.56.12762
9929.166.56.128/2629.166.56.129 to 29.166.56.19029.166.56.19162
10029.166.56.192/2629.166.56.193 to 29.166.56.25429.166.56.25562
10129.166.57.0/2629.166.57.1 to 29.166.57.6229.166.57.6362
10229.166.57.64/2629.166.57.65 to 29.166.57.12629.166.57.12762
10329.166.57.128/2629.166.57.129 to 29.166.57.19029.166.57.19162
10429.166.57.192/2629.166.57.193 to 29.166.57.25429.166.57.25562
10529.166.58.0/2629.166.58.1 to 29.166.58.6229.166.58.6362
10629.166.58.64/2629.166.58.65 to 29.166.58.12629.166.58.12762
10729.166.58.128/2629.166.58.129 to 29.166.58.19029.166.58.19162
10829.166.58.192/2629.166.58.193 to 29.166.58.25429.166.58.25562
10929.166.59.0/2629.166.59.1 to 29.166.59.6229.166.59.6362
11029.166.59.64/2629.166.59.65 to 29.166.59.12629.166.59.12762
11129.166.59.128/2629.166.59.129 to 29.166.59.19029.166.59.19162
11229.166.59.192/2629.166.59.193 to 29.166.59.25429.166.59.25562
11329.166.60.0/2629.166.60.1 to 29.166.60.6229.166.60.6362
11429.166.60.64/2629.166.60.65 to 29.166.60.12629.166.60.12762
11529.166.60.128/2629.166.60.129 to 29.166.60.19029.166.60.19162
11629.166.60.192/2629.166.60.193 to 29.166.60.25429.166.60.25562
11729.166.61.0/2629.166.61.1 to 29.166.61.6229.166.61.6362
11829.166.61.64/2629.166.61.65 to 29.166.61.12629.166.61.12762
11929.166.61.128/2629.166.61.129 to 29.166.61.19029.166.61.19162
12029.166.61.192/2629.166.61.193 to 29.166.61.25429.166.61.25562
12129.166.62.0/2629.166.62.1 to 29.166.62.6229.166.62.6362
12229.166.62.64/2629.166.62.65 to 29.166.62.12629.166.62.12762
12329.166.62.128/2629.166.62.129 to 29.166.62.19029.166.62.19162
12429.166.62.192/2629.166.62.193 to 29.166.62.25429.166.62.25562
12529.166.63.0/2629.166.63.1 to 29.166.63.6229.166.63.6362
12629.166.63.64/2629.166.63.65 to 29.166.63.12629.166.63.12762
12729.166.63.128/2629.166.63.129 to 29.166.63.19029.166.63.19162
12829.166.63.192/2629.166.63.193 to 29.166.63.25429.166.63.25562

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.