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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.

Network143.167.78.0/23
Usable hosts510
Subnet mask255.255.254.0
Addresses512
Network address
143.167.78.0
Broadcast address
143.167.79.255
First usable
143.167.78.1
Last usable
143.167.79.254
Usable hosts
510 (512 less the network and broadcast addresses)
Subnet mask
255.255.254.0
Wildcard mask
0.0.1.255 (Cisco ACLs, OSPF)
Prefix length
/23
Type
Public public
Old class
B (default /16)
As numbers
Hex 8FA74E00 · Integer 2410106368 to 2410106879
Reverse DNS zones
78.167.143.in-addr.arpa
79.167.143.in-addr.arpa
/23 is not on a 8-bit boundary, so it takes 2 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10001111.10100111.01001110.00000000143.167.78.0
Subnet mask11111111.11111111.11111110.00000000255.255.254.0
Network10001111.10100111.01001110.00000000143.167.78.0
Broadcast10001111.10100111.01001111.11111111143.167.79.255
Split into smaller subnets/29
/24 (2)/25 (4)/26 (8)/27 (16)/28 (32)/29 (64)/30 (128)/31 (256)/32 (512)

143.167.78.0/23 makes 64 subnets of /29.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1143.167.78.0/29143.167.78.1 to 143.167.78.6143.167.78.76
2143.167.78.8/29143.167.78.9 to 143.167.78.14143.167.78.156
3143.167.78.16/29143.167.78.17 to 143.167.78.22143.167.78.236
4143.167.78.24/29143.167.78.25 to 143.167.78.30143.167.78.316
5143.167.78.32/29143.167.78.33 to 143.167.78.38143.167.78.396
6143.167.78.40/29143.167.78.41 to 143.167.78.46143.167.78.476
7143.167.78.48/29143.167.78.49 to 143.167.78.54143.167.78.556
8143.167.78.56/29143.167.78.57 to 143.167.78.62143.167.78.636
9143.167.78.64/29143.167.78.65 to 143.167.78.70143.167.78.716
10143.167.78.72/29143.167.78.73 to 143.167.78.78143.167.78.796
11143.167.78.80/29143.167.78.81 to 143.167.78.86143.167.78.876
12143.167.78.88/29143.167.78.89 to 143.167.78.94143.167.78.956
13143.167.78.96/29143.167.78.97 to 143.167.78.102143.167.78.1036
14143.167.78.104/29143.167.78.105 to 143.167.78.110143.167.78.1116
15143.167.78.112/29143.167.78.113 to 143.167.78.118143.167.78.1196
16143.167.78.120/29143.167.78.121 to 143.167.78.126143.167.78.1276
17143.167.78.128/29143.167.78.129 to 143.167.78.134143.167.78.1356
18143.167.78.136/29143.167.78.137 to 143.167.78.142143.167.78.1436
19143.167.78.144/29143.167.78.145 to 143.167.78.150143.167.78.1516
20143.167.78.152/29143.167.78.153 to 143.167.78.158143.167.78.1596
21143.167.78.160/29143.167.78.161 to 143.167.78.166143.167.78.1676
22143.167.78.168/29143.167.78.169 to 143.167.78.174143.167.78.1756
23143.167.78.176/29143.167.78.177 to 143.167.78.182143.167.78.1836
24143.167.78.184/29143.167.78.185 to 143.167.78.190143.167.78.1916
25143.167.78.192/29143.167.78.193 to 143.167.78.198143.167.78.1996
26143.167.78.200/29143.167.78.201 to 143.167.78.206143.167.78.2076
27143.167.78.208/29143.167.78.209 to 143.167.78.214143.167.78.2156
28143.167.78.216/29143.167.78.217 to 143.167.78.222143.167.78.2236
29143.167.78.224/29143.167.78.225 to 143.167.78.230143.167.78.2316
30143.167.78.232/29143.167.78.233 to 143.167.78.238143.167.78.2396
31143.167.78.240/29143.167.78.241 to 143.167.78.246143.167.78.2476
32143.167.78.248/29143.167.78.249 to 143.167.78.254143.167.78.2556
33143.167.79.0/29143.167.79.1 to 143.167.79.6143.167.79.76
34143.167.79.8/29143.167.79.9 to 143.167.79.14143.167.79.156
35143.167.79.16/29143.167.79.17 to 143.167.79.22143.167.79.236
36143.167.79.24/29143.167.79.25 to 143.167.79.30143.167.79.316
37143.167.79.32/29143.167.79.33 to 143.167.79.38143.167.79.396
38143.167.79.40/29143.167.79.41 to 143.167.79.46143.167.79.476
39143.167.79.48/29143.167.79.49 to 143.167.79.54143.167.79.556
40143.167.79.56/29143.167.79.57 to 143.167.79.62143.167.79.636
41143.167.79.64/29143.167.79.65 to 143.167.79.70143.167.79.716
42143.167.79.72/29143.167.79.73 to 143.167.79.78143.167.79.796
43143.167.79.80/29143.167.79.81 to 143.167.79.86143.167.79.876
44143.167.79.88/29143.167.79.89 to 143.167.79.94143.167.79.956
45143.167.79.96/29143.167.79.97 to 143.167.79.102143.167.79.1036
46143.167.79.104/29143.167.79.105 to 143.167.79.110143.167.79.1116
47143.167.79.112/29143.167.79.113 to 143.167.79.118143.167.79.1196
48143.167.79.120/29143.167.79.121 to 143.167.79.126143.167.79.1276
49143.167.79.128/29143.167.79.129 to 143.167.79.134143.167.79.1356
50143.167.79.136/29143.167.79.137 to 143.167.79.142143.167.79.1436
51143.167.79.144/29143.167.79.145 to 143.167.79.150143.167.79.1516
52143.167.79.152/29143.167.79.153 to 143.167.79.158143.167.79.1596
53143.167.79.160/29143.167.79.161 to 143.167.79.166143.167.79.1676
54143.167.79.168/29143.167.79.169 to 143.167.79.174143.167.79.1756
55143.167.79.176/29143.167.79.177 to 143.167.79.182143.167.79.1836
56143.167.79.184/29143.167.79.185 to 143.167.79.190143.167.79.1916
57143.167.79.192/29143.167.79.193 to 143.167.79.198143.167.79.1996
58143.167.79.200/29143.167.79.201 to 143.167.79.206143.167.79.2076
59143.167.79.208/29143.167.79.209 to 143.167.79.214143.167.79.2156
60143.167.79.216/29143.167.79.217 to 143.167.79.222143.167.79.2236
61143.167.79.224/29143.167.79.225 to 143.167.79.230143.167.79.2316
62143.167.79.232/29143.167.79.233 to 143.167.79.238143.167.79.2396
63143.167.79.240/29143.167.79.241 to 143.167.79.246143.167.79.2476
64143.167.79.248/29143.167.79.249 to 143.167.79.254143.167.79.2556

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.