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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.

Network25.65.72.0/22
Usable hosts1,022
Subnet mask255.255.252.0
Addresses1,024
Network address
25.65.72.0
Broadcast address
25.65.75.255
First usable
25.65.72.1
Last usable
25.65.75.254
Usable hosts
1,022 (1,024 less the network and broadcast addresses)
Subnet mask
255.255.252.0
Wildcard mask
0.0.3.255 (Cisco ACLs, OSPF)
Prefix length
/22
Type
Public public
Old class
A (default /8)
As numbers
Hex 19414800 · Integer 423708672 to 423709695
Reverse DNS zones
72.65.25.in-addr.arpa
73.65.25.in-addr.arpa
74.65.25.in-addr.arpa
75.65.25.in-addr.arpa
/22 is not on a 8-bit boundary, so it takes 4 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00011001.01000001.01001000.0000000025.65.72.0
Subnet mask11111111.11111111.11111100.00000000255.255.252.0
Network00011001.01000001.01001000.0000000025.65.72.0
Broadcast00011001.01000001.01001011.1111111125.65.75.255
Split into smaller subnets/29
/23 (2)/24 (4)/25 (8)/26 (16)/27 (32)/28 (64)/29 (128)/30 (256)/31 (512)/32 (1,024)

25.65.72.0/22 makes 128 subnets of /29.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
125.65.72.0/2925.65.72.1 to 25.65.72.625.65.72.76
225.65.72.8/2925.65.72.9 to 25.65.72.1425.65.72.156
325.65.72.16/2925.65.72.17 to 25.65.72.2225.65.72.236
425.65.72.24/2925.65.72.25 to 25.65.72.3025.65.72.316
525.65.72.32/2925.65.72.33 to 25.65.72.3825.65.72.396
625.65.72.40/2925.65.72.41 to 25.65.72.4625.65.72.476
725.65.72.48/2925.65.72.49 to 25.65.72.5425.65.72.556
825.65.72.56/2925.65.72.57 to 25.65.72.6225.65.72.636
925.65.72.64/2925.65.72.65 to 25.65.72.7025.65.72.716
1025.65.72.72/2925.65.72.73 to 25.65.72.7825.65.72.796
1125.65.72.80/2925.65.72.81 to 25.65.72.8625.65.72.876
1225.65.72.88/2925.65.72.89 to 25.65.72.9425.65.72.956
1325.65.72.96/2925.65.72.97 to 25.65.72.10225.65.72.1036
1425.65.72.104/2925.65.72.105 to 25.65.72.11025.65.72.1116
1525.65.72.112/2925.65.72.113 to 25.65.72.11825.65.72.1196
1625.65.72.120/2925.65.72.121 to 25.65.72.12625.65.72.1276
1725.65.72.128/2925.65.72.129 to 25.65.72.13425.65.72.1356
1825.65.72.136/2925.65.72.137 to 25.65.72.14225.65.72.1436
1925.65.72.144/2925.65.72.145 to 25.65.72.15025.65.72.1516
2025.65.72.152/2925.65.72.153 to 25.65.72.15825.65.72.1596
2125.65.72.160/2925.65.72.161 to 25.65.72.16625.65.72.1676
2225.65.72.168/2925.65.72.169 to 25.65.72.17425.65.72.1756
2325.65.72.176/2925.65.72.177 to 25.65.72.18225.65.72.1836
2425.65.72.184/2925.65.72.185 to 25.65.72.19025.65.72.1916
2525.65.72.192/2925.65.72.193 to 25.65.72.19825.65.72.1996
2625.65.72.200/2925.65.72.201 to 25.65.72.20625.65.72.2076
2725.65.72.208/2925.65.72.209 to 25.65.72.21425.65.72.2156
2825.65.72.216/2925.65.72.217 to 25.65.72.22225.65.72.2236
2925.65.72.224/2925.65.72.225 to 25.65.72.23025.65.72.2316
3025.65.72.232/2925.65.72.233 to 25.65.72.23825.65.72.2396
3125.65.72.240/2925.65.72.241 to 25.65.72.24625.65.72.2476
3225.65.72.248/2925.65.72.249 to 25.65.72.25425.65.72.2556
3325.65.73.0/2925.65.73.1 to 25.65.73.625.65.73.76
3425.65.73.8/2925.65.73.9 to 25.65.73.1425.65.73.156
3525.65.73.16/2925.65.73.17 to 25.65.73.2225.65.73.236
3625.65.73.24/2925.65.73.25 to 25.65.73.3025.65.73.316
3725.65.73.32/2925.65.73.33 to 25.65.73.3825.65.73.396
3825.65.73.40/2925.65.73.41 to 25.65.73.4625.65.73.476
3925.65.73.48/2925.65.73.49 to 25.65.73.5425.65.73.556
4025.65.73.56/2925.65.73.57 to 25.65.73.6225.65.73.636
4125.65.73.64/2925.65.73.65 to 25.65.73.7025.65.73.716
4225.65.73.72/2925.65.73.73 to 25.65.73.7825.65.73.796
4325.65.73.80/2925.65.73.81 to 25.65.73.8625.65.73.876
4425.65.73.88/2925.65.73.89 to 25.65.73.9425.65.73.956
4525.65.73.96/2925.65.73.97 to 25.65.73.10225.65.73.1036
4625.65.73.104/2925.65.73.105 to 25.65.73.11025.65.73.1116
4725.65.73.112/2925.65.73.113 to 25.65.73.11825.65.73.1196
4825.65.73.120/2925.65.73.121 to 25.65.73.12625.65.73.1276
4925.65.73.128/2925.65.73.129 to 25.65.73.13425.65.73.1356
5025.65.73.136/2925.65.73.137 to 25.65.73.14225.65.73.1436
5125.65.73.144/2925.65.73.145 to 25.65.73.15025.65.73.1516
5225.65.73.152/2925.65.73.153 to 25.65.73.15825.65.73.1596
5325.65.73.160/2925.65.73.161 to 25.65.73.16625.65.73.1676
5425.65.73.168/2925.65.73.169 to 25.65.73.17425.65.73.1756
5525.65.73.176/2925.65.73.177 to 25.65.73.18225.65.73.1836
5625.65.73.184/2925.65.73.185 to 25.65.73.19025.65.73.1916
5725.65.73.192/2925.65.73.193 to 25.65.73.19825.65.73.1996
5825.65.73.200/2925.65.73.201 to 25.65.73.20625.65.73.2076
5925.65.73.208/2925.65.73.209 to 25.65.73.21425.65.73.2156
6025.65.73.216/2925.65.73.217 to 25.65.73.22225.65.73.2236
6125.65.73.224/2925.65.73.225 to 25.65.73.23025.65.73.2316
6225.65.73.232/2925.65.73.233 to 25.65.73.23825.65.73.2396
6325.65.73.240/2925.65.73.241 to 25.65.73.24625.65.73.2476
6425.65.73.248/2925.65.73.249 to 25.65.73.25425.65.73.2556
6525.65.74.0/2925.65.74.1 to 25.65.74.625.65.74.76
6625.65.74.8/2925.65.74.9 to 25.65.74.1425.65.74.156
6725.65.74.16/2925.65.74.17 to 25.65.74.2225.65.74.236
6825.65.74.24/2925.65.74.25 to 25.65.74.3025.65.74.316
6925.65.74.32/2925.65.74.33 to 25.65.74.3825.65.74.396
7025.65.74.40/2925.65.74.41 to 25.65.74.4625.65.74.476
7125.65.74.48/2925.65.74.49 to 25.65.74.5425.65.74.556
7225.65.74.56/2925.65.74.57 to 25.65.74.6225.65.74.636
7325.65.74.64/2925.65.74.65 to 25.65.74.7025.65.74.716
7425.65.74.72/2925.65.74.73 to 25.65.74.7825.65.74.796
7525.65.74.80/2925.65.74.81 to 25.65.74.8625.65.74.876
7625.65.74.88/2925.65.74.89 to 25.65.74.9425.65.74.956
7725.65.74.96/2925.65.74.97 to 25.65.74.10225.65.74.1036
7825.65.74.104/2925.65.74.105 to 25.65.74.11025.65.74.1116
7925.65.74.112/2925.65.74.113 to 25.65.74.11825.65.74.1196
8025.65.74.120/2925.65.74.121 to 25.65.74.12625.65.74.1276
8125.65.74.128/2925.65.74.129 to 25.65.74.13425.65.74.1356
8225.65.74.136/2925.65.74.137 to 25.65.74.14225.65.74.1436
8325.65.74.144/2925.65.74.145 to 25.65.74.15025.65.74.1516
8425.65.74.152/2925.65.74.153 to 25.65.74.15825.65.74.1596
8525.65.74.160/2925.65.74.161 to 25.65.74.16625.65.74.1676
8625.65.74.168/2925.65.74.169 to 25.65.74.17425.65.74.1756
8725.65.74.176/2925.65.74.177 to 25.65.74.18225.65.74.1836
8825.65.74.184/2925.65.74.185 to 25.65.74.19025.65.74.1916
8925.65.74.192/2925.65.74.193 to 25.65.74.19825.65.74.1996
9025.65.74.200/2925.65.74.201 to 25.65.74.20625.65.74.2076
9125.65.74.208/2925.65.74.209 to 25.65.74.21425.65.74.2156
9225.65.74.216/2925.65.74.217 to 25.65.74.22225.65.74.2236
9325.65.74.224/2925.65.74.225 to 25.65.74.23025.65.74.2316
9425.65.74.232/2925.65.74.233 to 25.65.74.23825.65.74.2396
9525.65.74.240/2925.65.74.241 to 25.65.74.24625.65.74.2476
9625.65.74.248/2925.65.74.249 to 25.65.74.25425.65.74.2556
9725.65.75.0/2925.65.75.1 to 25.65.75.625.65.75.76
9825.65.75.8/2925.65.75.9 to 25.65.75.1425.65.75.156
9925.65.75.16/2925.65.75.17 to 25.65.75.2225.65.75.236
10025.65.75.24/2925.65.75.25 to 25.65.75.3025.65.75.316
10125.65.75.32/2925.65.75.33 to 25.65.75.3825.65.75.396
10225.65.75.40/2925.65.75.41 to 25.65.75.4625.65.75.476
10325.65.75.48/2925.65.75.49 to 25.65.75.5425.65.75.556
10425.65.75.56/2925.65.75.57 to 25.65.75.6225.65.75.636
10525.65.75.64/2925.65.75.65 to 25.65.75.7025.65.75.716
10625.65.75.72/2925.65.75.73 to 25.65.75.7825.65.75.796
10725.65.75.80/2925.65.75.81 to 25.65.75.8625.65.75.876
10825.65.75.88/2925.65.75.89 to 25.65.75.9425.65.75.956
10925.65.75.96/2925.65.75.97 to 25.65.75.10225.65.75.1036
11025.65.75.104/2925.65.75.105 to 25.65.75.11025.65.75.1116
11125.65.75.112/2925.65.75.113 to 25.65.75.11825.65.75.1196
11225.65.75.120/2925.65.75.121 to 25.65.75.12625.65.75.1276
11325.65.75.128/2925.65.75.129 to 25.65.75.13425.65.75.1356
11425.65.75.136/2925.65.75.137 to 25.65.75.14225.65.75.1436
11525.65.75.144/2925.65.75.145 to 25.65.75.15025.65.75.1516
11625.65.75.152/2925.65.75.153 to 25.65.75.15825.65.75.1596
11725.65.75.160/2925.65.75.161 to 25.65.75.16625.65.75.1676
11825.65.75.168/2925.65.75.169 to 25.65.75.17425.65.75.1756
11925.65.75.176/2925.65.75.177 to 25.65.75.18225.65.75.1836
12025.65.75.184/2925.65.75.185 to 25.65.75.19025.65.75.1916
12125.65.75.192/2925.65.75.193 to 25.65.75.19825.65.75.1996
12225.65.75.200/2925.65.75.201 to 25.65.75.20625.65.75.2076
12325.65.75.208/2925.65.75.209 to 25.65.75.21425.65.75.2156
12425.65.75.216/2925.65.75.217 to 25.65.75.22225.65.75.2236
12525.65.75.224/2925.65.75.225 to 25.65.75.23025.65.75.2316
12625.65.75.232/2925.65.75.233 to 25.65.75.23825.65.75.2396
12725.65.75.240/2925.65.75.241 to 25.65.75.24625.65.75.2476
12825.65.75.248/2925.65.75.249 to 25.65.75.25425.65.75.2556

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.