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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.

Network143.167.166.0/23
Usable hosts510
Subnet mask255.255.254.0
Addresses512
Network address
143.167.166.0
Broadcast address
143.167.167.255
First usable
143.167.166.1
Last usable
143.167.167.254
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 8FA7A600 · Integer 2410128896 to 2410129407
Reverse DNS zones
166.167.143.in-addr.arpa
167.167.143.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
Address10001111.10100111.10100110.00000000143.167.166.0
Subnet mask11111111.11111111.11111110.00000000255.255.254.0
Network10001111.10100111.10100110.00000000143.167.166.0
Broadcast10001111.10100111.10100111.11111111143.167.167.255
Split into smaller subnets/30
/24 (2)/25 (4)/26 (8)/27 (16)/28 (32)/29 (64)/30 (128)/31 (256)/32 (512)

143.167.166.0/23 makes 128 subnets of /30.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1143.167.166.0/30143.167.166.1 to 143.167.166.2143.167.166.32
2143.167.166.4/30143.167.166.5 to 143.167.166.6143.167.166.72
3143.167.166.8/30143.167.166.9 to 143.167.166.10143.167.166.112
4143.167.166.12/30143.167.166.13 to 143.167.166.14143.167.166.152
5143.167.166.16/30143.167.166.17 to 143.167.166.18143.167.166.192
6143.167.166.20/30143.167.166.21 to 143.167.166.22143.167.166.232
7143.167.166.24/30143.167.166.25 to 143.167.166.26143.167.166.272
8143.167.166.28/30143.167.166.29 to 143.167.166.30143.167.166.312
9143.167.166.32/30143.167.166.33 to 143.167.166.34143.167.166.352
10143.167.166.36/30143.167.166.37 to 143.167.166.38143.167.166.392
11143.167.166.40/30143.167.166.41 to 143.167.166.42143.167.166.432
12143.167.166.44/30143.167.166.45 to 143.167.166.46143.167.166.472
13143.167.166.48/30143.167.166.49 to 143.167.166.50143.167.166.512
14143.167.166.52/30143.167.166.53 to 143.167.166.54143.167.166.552
15143.167.166.56/30143.167.166.57 to 143.167.166.58143.167.166.592
16143.167.166.60/30143.167.166.61 to 143.167.166.62143.167.166.632
17143.167.166.64/30143.167.166.65 to 143.167.166.66143.167.166.672
18143.167.166.68/30143.167.166.69 to 143.167.166.70143.167.166.712
19143.167.166.72/30143.167.166.73 to 143.167.166.74143.167.166.752
20143.167.166.76/30143.167.166.77 to 143.167.166.78143.167.166.792
21143.167.166.80/30143.167.166.81 to 143.167.166.82143.167.166.832
22143.167.166.84/30143.167.166.85 to 143.167.166.86143.167.166.872
23143.167.166.88/30143.167.166.89 to 143.167.166.90143.167.166.912
24143.167.166.92/30143.167.166.93 to 143.167.166.94143.167.166.952
25143.167.166.96/30143.167.166.97 to 143.167.166.98143.167.166.992
26143.167.166.100/30143.167.166.101 to 143.167.166.102143.167.166.1032
27143.167.166.104/30143.167.166.105 to 143.167.166.106143.167.166.1072
28143.167.166.108/30143.167.166.109 to 143.167.166.110143.167.166.1112
29143.167.166.112/30143.167.166.113 to 143.167.166.114143.167.166.1152
30143.167.166.116/30143.167.166.117 to 143.167.166.118143.167.166.1192
31143.167.166.120/30143.167.166.121 to 143.167.166.122143.167.166.1232
32143.167.166.124/30143.167.166.125 to 143.167.166.126143.167.166.1272
33143.167.166.128/30143.167.166.129 to 143.167.166.130143.167.166.1312
34143.167.166.132/30143.167.166.133 to 143.167.166.134143.167.166.1352
35143.167.166.136/30143.167.166.137 to 143.167.166.138143.167.166.1392
36143.167.166.140/30143.167.166.141 to 143.167.166.142143.167.166.1432
37143.167.166.144/30143.167.166.145 to 143.167.166.146143.167.166.1472
38143.167.166.148/30143.167.166.149 to 143.167.166.150143.167.166.1512
39143.167.166.152/30143.167.166.153 to 143.167.166.154143.167.166.1552
40143.167.166.156/30143.167.166.157 to 143.167.166.158143.167.166.1592
41143.167.166.160/30143.167.166.161 to 143.167.166.162143.167.166.1632
42143.167.166.164/30143.167.166.165 to 143.167.166.166143.167.166.1672
43143.167.166.168/30143.167.166.169 to 143.167.166.170143.167.166.1712
44143.167.166.172/30143.167.166.173 to 143.167.166.174143.167.166.1752
45143.167.166.176/30143.167.166.177 to 143.167.166.178143.167.166.1792
46143.167.166.180/30143.167.166.181 to 143.167.166.182143.167.166.1832
47143.167.166.184/30143.167.166.185 to 143.167.166.186143.167.166.1872
48143.167.166.188/30143.167.166.189 to 143.167.166.190143.167.166.1912
49143.167.166.192/30143.167.166.193 to 143.167.166.194143.167.166.1952
50143.167.166.196/30143.167.166.197 to 143.167.166.198143.167.166.1992
51143.167.166.200/30143.167.166.201 to 143.167.166.202143.167.166.2032
52143.167.166.204/30143.167.166.205 to 143.167.166.206143.167.166.2072
53143.167.166.208/30143.167.166.209 to 143.167.166.210143.167.166.2112
54143.167.166.212/30143.167.166.213 to 143.167.166.214143.167.166.2152
55143.167.166.216/30143.167.166.217 to 143.167.166.218143.167.166.2192
56143.167.166.220/30143.167.166.221 to 143.167.166.222143.167.166.2232
57143.167.166.224/30143.167.166.225 to 143.167.166.226143.167.166.2272
58143.167.166.228/30143.167.166.229 to 143.167.166.230143.167.166.2312
59143.167.166.232/30143.167.166.233 to 143.167.166.234143.167.166.2352
60143.167.166.236/30143.167.166.237 to 143.167.166.238143.167.166.2392
61143.167.166.240/30143.167.166.241 to 143.167.166.242143.167.166.2432
62143.167.166.244/30143.167.166.245 to 143.167.166.246143.167.166.2472
63143.167.166.248/30143.167.166.249 to 143.167.166.250143.167.166.2512
64143.167.166.252/30143.167.166.253 to 143.167.166.254143.167.166.2552
65143.167.167.0/30143.167.167.1 to 143.167.167.2143.167.167.32
66143.167.167.4/30143.167.167.5 to 143.167.167.6143.167.167.72
67143.167.167.8/30143.167.167.9 to 143.167.167.10143.167.167.112
68143.167.167.12/30143.167.167.13 to 143.167.167.14143.167.167.152
69143.167.167.16/30143.167.167.17 to 143.167.167.18143.167.167.192
70143.167.167.20/30143.167.167.21 to 143.167.167.22143.167.167.232
71143.167.167.24/30143.167.167.25 to 143.167.167.26143.167.167.272
72143.167.167.28/30143.167.167.29 to 143.167.167.30143.167.167.312
73143.167.167.32/30143.167.167.33 to 143.167.167.34143.167.167.352
74143.167.167.36/30143.167.167.37 to 143.167.167.38143.167.167.392
75143.167.167.40/30143.167.167.41 to 143.167.167.42143.167.167.432
76143.167.167.44/30143.167.167.45 to 143.167.167.46143.167.167.472
77143.167.167.48/30143.167.167.49 to 143.167.167.50143.167.167.512
78143.167.167.52/30143.167.167.53 to 143.167.167.54143.167.167.552
79143.167.167.56/30143.167.167.57 to 143.167.167.58143.167.167.592
80143.167.167.60/30143.167.167.61 to 143.167.167.62143.167.167.632
81143.167.167.64/30143.167.167.65 to 143.167.167.66143.167.167.672
82143.167.167.68/30143.167.167.69 to 143.167.167.70143.167.167.712
83143.167.167.72/30143.167.167.73 to 143.167.167.74143.167.167.752
84143.167.167.76/30143.167.167.77 to 143.167.167.78143.167.167.792
85143.167.167.80/30143.167.167.81 to 143.167.167.82143.167.167.832
86143.167.167.84/30143.167.167.85 to 143.167.167.86143.167.167.872
87143.167.167.88/30143.167.167.89 to 143.167.167.90143.167.167.912
88143.167.167.92/30143.167.167.93 to 143.167.167.94143.167.167.952
89143.167.167.96/30143.167.167.97 to 143.167.167.98143.167.167.992
90143.167.167.100/30143.167.167.101 to 143.167.167.102143.167.167.1032
91143.167.167.104/30143.167.167.105 to 143.167.167.106143.167.167.1072
92143.167.167.108/30143.167.167.109 to 143.167.167.110143.167.167.1112
93143.167.167.112/30143.167.167.113 to 143.167.167.114143.167.167.1152
94143.167.167.116/30143.167.167.117 to 143.167.167.118143.167.167.1192
95143.167.167.120/30143.167.167.121 to 143.167.167.122143.167.167.1232
96143.167.167.124/30143.167.167.125 to 143.167.167.126143.167.167.1272
97143.167.167.128/30143.167.167.129 to 143.167.167.130143.167.167.1312
98143.167.167.132/30143.167.167.133 to 143.167.167.134143.167.167.1352
99143.167.167.136/30143.167.167.137 to 143.167.167.138143.167.167.1392
100143.167.167.140/30143.167.167.141 to 143.167.167.142143.167.167.1432
101143.167.167.144/30143.167.167.145 to 143.167.167.146143.167.167.1472
102143.167.167.148/30143.167.167.149 to 143.167.167.150143.167.167.1512
103143.167.167.152/30143.167.167.153 to 143.167.167.154143.167.167.1552
104143.167.167.156/30143.167.167.157 to 143.167.167.158143.167.167.1592
105143.167.167.160/30143.167.167.161 to 143.167.167.162143.167.167.1632
106143.167.167.164/30143.167.167.165 to 143.167.167.166143.167.167.1672
107143.167.167.168/30143.167.167.169 to 143.167.167.170143.167.167.1712
108143.167.167.172/30143.167.167.173 to 143.167.167.174143.167.167.1752
109143.167.167.176/30143.167.167.177 to 143.167.167.178143.167.167.1792
110143.167.167.180/30143.167.167.181 to 143.167.167.182143.167.167.1832
111143.167.167.184/30143.167.167.185 to 143.167.167.186143.167.167.1872
112143.167.167.188/30143.167.167.189 to 143.167.167.190143.167.167.1912
113143.167.167.192/30143.167.167.193 to 143.167.167.194143.167.167.1952
114143.167.167.196/30143.167.167.197 to 143.167.167.198143.167.167.1992
115143.167.167.200/30143.167.167.201 to 143.167.167.202143.167.167.2032
116143.167.167.204/30143.167.167.205 to 143.167.167.206143.167.167.2072
117143.167.167.208/30143.167.167.209 to 143.167.167.210143.167.167.2112
118143.167.167.212/30143.167.167.213 to 143.167.167.214143.167.167.2152
119143.167.167.216/30143.167.167.217 to 143.167.167.218143.167.167.2192
120143.167.167.220/30143.167.167.221 to 143.167.167.222143.167.167.2232
121143.167.167.224/30143.167.167.225 to 143.167.167.226143.167.167.2272
122143.167.167.228/30143.167.167.229 to 143.167.167.230143.167.167.2312
123143.167.167.232/30143.167.167.233 to 143.167.167.234143.167.167.2352
124143.167.167.236/30143.167.167.237 to 143.167.167.238143.167.167.2392
125143.167.167.240/30143.167.167.241 to 143.167.167.242143.167.167.2432
126143.167.167.244/30143.167.167.245 to 143.167.167.246143.167.167.2472
127143.167.167.248/30143.167.167.249 to 143.167.167.250143.167.167.2512
128143.167.167.252/30143.167.167.253 to 143.167.167.254143.167.167.2552

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.