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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.

Network245.74.4.0/22
Usable hosts1,022
Subnet mask255.255.252.0
Addresses1,024
Network address
245.74.4.0
Broadcast address
245.74.7.255
First usable
245.74.4.1
Last usable
245.74.7.254
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
Reserved 240.0.0.0/4
Future use; not usable on most systems
Old class
E (reserved)
As numbers
Hex F54A0400 · Integer 4115268608 to 4115269631
Reverse DNS zones
4.74.245.in-addr.arpa
5.74.245.in-addr.arpa
6.74.245.in-addr.arpa
7.74.245.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
Address11110101.01001010.00000100.00000000245.74.4.0
Subnet mask11111111.11111111.11111100.00000000255.255.252.0
Network11110101.01001010.00000100.00000000245.74.4.0
Broadcast11110101.01001010.00000111.11111111245.74.7.255
Split into smaller subnets/28
/23 (2)/24 (4)/25 (8)/26 (16)/27 (32)/28 (64)/29 (128)/30 (256)/31 (512)/32 (1,024)

245.74.4.0/22 makes 64 subnets of /28.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1245.74.4.0/28245.74.4.1 to 245.74.4.14245.74.4.1514
2245.74.4.16/28245.74.4.17 to 245.74.4.30245.74.4.3114
3245.74.4.32/28245.74.4.33 to 245.74.4.46245.74.4.4714
4245.74.4.48/28245.74.4.49 to 245.74.4.62245.74.4.6314
5245.74.4.64/28245.74.4.65 to 245.74.4.78245.74.4.7914
6245.74.4.80/28245.74.4.81 to 245.74.4.94245.74.4.9514
7245.74.4.96/28245.74.4.97 to 245.74.4.110245.74.4.11114
8245.74.4.112/28245.74.4.113 to 245.74.4.126245.74.4.12714
9245.74.4.128/28245.74.4.129 to 245.74.4.142245.74.4.14314
10245.74.4.144/28245.74.4.145 to 245.74.4.158245.74.4.15914
11245.74.4.160/28245.74.4.161 to 245.74.4.174245.74.4.17514
12245.74.4.176/28245.74.4.177 to 245.74.4.190245.74.4.19114
13245.74.4.192/28245.74.4.193 to 245.74.4.206245.74.4.20714
14245.74.4.208/28245.74.4.209 to 245.74.4.222245.74.4.22314
15245.74.4.224/28245.74.4.225 to 245.74.4.238245.74.4.23914
16245.74.4.240/28245.74.4.241 to 245.74.4.254245.74.4.25514
17245.74.5.0/28245.74.5.1 to 245.74.5.14245.74.5.1514
18245.74.5.16/28245.74.5.17 to 245.74.5.30245.74.5.3114
19245.74.5.32/28245.74.5.33 to 245.74.5.46245.74.5.4714
20245.74.5.48/28245.74.5.49 to 245.74.5.62245.74.5.6314
21245.74.5.64/28245.74.5.65 to 245.74.5.78245.74.5.7914
22245.74.5.80/28245.74.5.81 to 245.74.5.94245.74.5.9514
23245.74.5.96/28245.74.5.97 to 245.74.5.110245.74.5.11114
24245.74.5.112/28245.74.5.113 to 245.74.5.126245.74.5.12714
25245.74.5.128/28245.74.5.129 to 245.74.5.142245.74.5.14314
26245.74.5.144/28245.74.5.145 to 245.74.5.158245.74.5.15914
27245.74.5.160/28245.74.5.161 to 245.74.5.174245.74.5.17514
28245.74.5.176/28245.74.5.177 to 245.74.5.190245.74.5.19114
29245.74.5.192/28245.74.5.193 to 245.74.5.206245.74.5.20714
30245.74.5.208/28245.74.5.209 to 245.74.5.222245.74.5.22314
31245.74.5.224/28245.74.5.225 to 245.74.5.238245.74.5.23914
32245.74.5.240/28245.74.5.241 to 245.74.5.254245.74.5.25514
33245.74.6.0/28245.74.6.1 to 245.74.6.14245.74.6.1514
34245.74.6.16/28245.74.6.17 to 245.74.6.30245.74.6.3114
35245.74.6.32/28245.74.6.33 to 245.74.6.46245.74.6.4714
36245.74.6.48/28245.74.6.49 to 245.74.6.62245.74.6.6314
37245.74.6.64/28245.74.6.65 to 245.74.6.78245.74.6.7914
38245.74.6.80/28245.74.6.81 to 245.74.6.94245.74.6.9514
39245.74.6.96/28245.74.6.97 to 245.74.6.110245.74.6.11114
40245.74.6.112/28245.74.6.113 to 245.74.6.126245.74.6.12714
41245.74.6.128/28245.74.6.129 to 245.74.6.142245.74.6.14314
42245.74.6.144/28245.74.6.145 to 245.74.6.158245.74.6.15914
43245.74.6.160/28245.74.6.161 to 245.74.6.174245.74.6.17514
44245.74.6.176/28245.74.6.177 to 245.74.6.190245.74.6.19114
45245.74.6.192/28245.74.6.193 to 245.74.6.206245.74.6.20714
46245.74.6.208/28245.74.6.209 to 245.74.6.222245.74.6.22314
47245.74.6.224/28245.74.6.225 to 245.74.6.238245.74.6.23914
48245.74.6.240/28245.74.6.241 to 245.74.6.254245.74.6.25514
49245.74.7.0/28245.74.7.1 to 245.74.7.14245.74.7.1514
50245.74.7.16/28245.74.7.17 to 245.74.7.30245.74.7.3114
51245.74.7.32/28245.74.7.33 to 245.74.7.46245.74.7.4714
52245.74.7.48/28245.74.7.49 to 245.74.7.62245.74.7.6314
53245.74.7.64/28245.74.7.65 to 245.74.7.78245.74.7.7914
54245.74.7.80/28245.74.7.81 to 245.74.7.94245.74.7.9514
55245.74.7.96/28245.74.7.97 to 245.74.7.110245.74.7.11114
56245.74.7.112/28245.74.7.113 to 245.74.7.126245.74.7.12714
57245.74.7.128/28245.74.7.129 to 245.74.7.142245.74.7.14314
58245.74.7.144/28245.74.7.145 to 245.74.7.158245.74.7.15914
59245.74.7.160/28245.74.7.161 to 245.74.7.174245.74.7.17514
60245.74.7.176/28245.74.7.177 to 245.74.7.190245.74.7.19114
61245.74.7.192/28245.74.7.193 to 245.74.7.206245.74.7.20714
62245.74.7.208/28245.74.7.209 to 245.74.7.222245.74.7.22314
63245.74.7.224/28245.74.7.225 to 245.74.7.238245.74.7.23914
64245.74.7.240/28245.74.7.241 to 245.74.7.254245.74.7.25514

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.