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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.

Network227.136.76.0/23
Usable hosts510
Subnet mask255.255.254.0
Addresses512
Network address
227.136.76.0
Broadcast address
227.136.77.255
First usable
227.136.76.1
Last usable
227.136.77.254
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
Multicast 224.0.0.0/4
One-to-many traffic, such as IPTV and routing protocols
Old class
D (multicast)
As numbers
Hex E3884C00 · Integer 3817360384 to 3817360895
Reverse DNS zones
76.136.227.in-addr.arpa
77.136.227.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
Address11100011.10001000.01001100.00000000227.136.76.0
Subnet mask11111111.11111111.11111110.00000000255.255.254.0
Network11100011.10001000.01001100.00000000227.136.76.0
Broadcast11100011.10001000.01001101.11111111227.136.77.255
Split into smaller subnets/30
/24 (2)/25 (4)/26 (8)/27 (16)/28 (32)/29 (64)/30 (128)/31 (256)/32 (512)

227.136.76.0/23 makes 128 subnets of /30.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1227.136.76.0/30227.136.76.1 to 227.136.76.2227.136.76.32
2227.136.76.4/30227.136.76.5 to 227.136.76.6227.136.76.72
3227.136.76.8/30227.136.76.9 to 227.136.76.10227.136.76.112
4227.136.76.12/30227.136.76.13 to 227.136.76.14227.136.76.152
5227.136.76.16/30227.136.76.17 to 227.136.76.18227.136.76.192
6227.136.76.20/30227.136.76.21 to 227.136.76.22227.136.76.232
7227.136.76.24/30227.136.76.25 to 227.136.76.26227.136.76.272
8227.136.76.28/30227.136.76.29 to 227.136.76.30227.136.76.312
9227.136.76.32/30227.136.76.33 to 227.136.76.34227.136.76.352
10227.136.76.36/30227.136.76.37 to 227.136.76.38227.136.76.392
11227.136.76.40/30227.136.76.41 to 227.136.76.42227.136.76.432
12227.136.76.44/30227.136.76.45 to 227.136.76.46227.136.76.472
13227.136.76.48/30227.136.76.49 to 227.136.76.50227.136.76.512
14227.136.76.52/30227.136.76.53 to 227.136.76.54227.136.76.552
15227.136.76.56/30227.136.76.57 to 227.136.76.58227.136.76.592
16227.136.76.60/30227.136.76.61 to 227.136.76.62227.136.76.632
17227.136.76.64/30227.136.76.65 to 227.136.76.66227.136.76.672
18227.136.76.68/30227.136.76.69 to 227.136.76.70227.136.76.712
19227.136.76.72/30227.136.76.73 to 227.136.76.74227.136.76.752
20227.136.76.76/30227.136.76.77 to 227.136.76.78227.136.76.792
21227.136.76.80/30227.136.76.81 to 227.136.76.82227.136.76.832
22227.136.76.84/30227.136.76.85 to 227.136.76.86227.136.76.872
23227.136.76.88/30227.136.76.89 to 227.136.76.90227.136.76.912
24227.136.76.92/30227.136.76.93 to 227.136.76.94227.136.76.952
25227.136.76.96/30227.136.76.97 to 227.136.76.98227.136.76.992
26227.136.76.100/30227.136.76.101 to 227.136.76.102227.136.76.1032
27227.136.76.104/30227.136.76.105 to 227.136.76.106227.136.76.1072
28227.136.76.108/30227.136.76.109 to 227.136.76.110227.136.76.1112
29227.136.76.112/30227.136.76.113 to 227.136.76.114227.136.76.1152
30227.136.76.116/30227.136.76.117 to 227.136.76.118227.136.76.1192
31227.136.76.120/30227.136.76.121 to 227.136.76.122227.136.76.1232
32227.136.76.124/30227.136.76.125 to 227.136.76.126227.136.76.1272
33227.136.76.128/30227.136.76.129 to 227.136.76.130227.136.76.1312
34227.136.76.132/30227.136.76.133 to 227.136.76.134227.136.76.1352
35227.136.76.136/30227.136.76.137 to 227.136.76.138227.136.76.1392
36227.136.76.140/30227.136.76.141 to 227.136.76.142227.136.76.1432
37227.136.76.144/30227.136.76.145 to 227.136.76.146227.136.76.1472
38227.136.76.148/30227.136.76.149 to 227.136.76.150227.136.76.1512
39227.136.76.152/30227.136.76.153 to 227.136.76.154227.136.76.1552
40227.136.76.156/30227.136.76.157 to 227.136.76.158227.136.76.1592
41227.136.76.160/30227.136.76.161 to 227.136.76.162227.136.76.1632
42227.136.76.164/30227.136.76.165 to 227.136.76.166227.136.76.1672
43227.136.76.168/30227.136.76.169 to 227.136.76.170227.136.76.1712
44227.136.76.172/30227.136.76.173 to 227.136.76.174227.136.76.1752
45227.136.76.176/30227.136.76.177 to 227.136.76.178227.136.76.1792
46227.136.76.180/30227.136.76.181 to 227.136.76.182227.136.76.1832
47227.136.76.184/30227.136.76.185 to 227.136.76.186227.136.76.1872
48227.136.76.188/30227.136.76.189 to 227.136.76.190227.136.76.1912
49227.136.76.192/30227.136.76.193 to 227.136.76.194227.136.76.1952
50227.136.76.196/30227.136.76.197 to 227.136.76.198227.136.76.1992
51227.136.76.200/30227.136.76.201 to 227.136.76.202227.136.76.2032
52227.136.76.204/30227.136.76.205 to 227.136.76.206227.136.76.2072
53227.136.76.208/30227.136.76.209 to 227.136.76.210227.136.76.2112
54227.136.76.212/30227.136.76.213 to 227.136.76.214227.136.76.2152
55227.136.76.216/30227.136.76.217 to 227.136.76.218227.136.76.2192
56227.136.76.220/30227.136.76.221 to 227.136.76.222227.136.76.2232
57227.136.76.224/30227.136.76.225 to 227.136.76.226227.136.76.2272
58227.136.76.228/30227.136.76.229 to 227.136.76.230227.136.76.2312
59227.136.76.232/30227.136.76.233 to 227.136.76.234227.136.76.2352
60227.136.76.236/30227.136.76.237 to 227.136.76.238227.136.76.2392
61227.136.76.240/30227.136.76.241 to 227.136.76.242227.136.76.2432
62227.136.76.244/30227.136.76.245 to 227.136.76.246227.136.76.2472
63227.136.76.248/30227.136.76.249 to 227.136.76.250227.136.76.2512
64227.136.76.252/30227.136.76.253 to 227.136.76.254227.136.76.2552
65227.136.77.0/30227.136.77.1 to 227.136.77.2227.136.77.32
66227.136.77.4/30227.136.77.5 to 227.136.77.6227.136.77.72
67227.136.77.8/30227.136.77.9 to 227.136.77.10227.136.77.112
68227.136.77.12/30227.136.77.13 to 227.136.77.14227.136.77.152
69227.136.77.16/30227.136.77.17 to 227.136.77.18227.136.77.192
70227.136.77.20/30227.136.77.21 to 227.136.77.22227.136.77.232
71227.136.77.24/30227.136.77.25 to 227.136.77.26227.136.77.272
72227.136.77.28/30227.136.77.29 to 227.136.77.30227.136.77.312
73227.136.77.32/30227.136.77.33 to 227.136.77.34227.136.77.352
74227.136.77.36/30227.136.77.37 to 227.136.77.38227.136.77.392
75227.136.77.40/30227.136.77.41 to 227.136.77.42227.136.77.432
76227.136.77.44/30227.136.77.45 to 227.136.77.46227.136.77.472
77227.136.77.48/30227.136.77.49 to 227.136.77.50227.136.77.512
78227.136.77.52/30227.136.77.53 to 227.136.77.54227.136.77.552
79227.136.77.56/30227.136.77.57 to 227.136.77.58227.136.77.592
80227.136.77.60/30227.136.77.61 to 227.136.77.62227.136.77.632
81227.136.77.64/30227.136.77.65 to 227.136.77.66227.136.77.672
82227.136.77.68/30227.136.77.69 to 227.136.77.70227.136.77.712
83227.136.77.72/30227.136.77.73 to 227.136.77.74227.136.77.752
84227.136.77.76/30227.136.77.77 to 227.136.77.78227.136.77.792
85227.136.77.80/30227.136.77.81 to 227.136.77.82227.136.77.832
86227.136.77.84/30227.136.77.85 to 227.136.77.86227.136.77.872
87227.136.77.88/30227.136.77.89 to 227.136.77.90227.136.77.912
88227.136.77.92/30227.136.77.93 to 227.136.77.94227.136.77.952
89227.136.77.96/30227.136.77.97 to 227.136.77.98227.136.77.992
90227.136.77.100/30227.136.77.101 to 227.136.77.102227.136.77.1032
91227.136.77.104/30227.136.77.105 to 227.136.77.106227.136.77.1072
92227.136.77.108/30227.136.77.109 to 227.136.77.110227.136.77.1112
93227.136.77.112/30227.136.77.113 to 227.136.77.114227.136.77.1152
94227.136.77.116/30227.136.77.117 to 227.136.77.118227.136.77.1192
95227.136.77.120/30227.136.77.121 to 227.136.77.122227.136.77.1232
96227.136.77.124/30227.136.77.125 to 227.136.77.126227.136.77.1272
97227.136.77.128/30227.136.77.129 to 227.136.77.130227.136.77.1312
98227.136.77.132/30227.136.77.133 to 227.136.77.134227.136.77.1352
99227.136.77.136/30227.136.77.137 to 227.136.77.138227.136.77.1392
100227.136.77.140/30227.136.77.141 to 227.136.77.142227.136.77.1432
101227.136.77.144/30227.136.77.145 to 227.136.77.146227.136.77.1472
102227.136.77.148/30227.136.77.149 to 227.136.77.150227.136.77.1512
103227.136.77.152/30227.136.77.153 to 227.136.77.154227.136.77.1552
104227.136.77.156/30227.136.77.157 to 227.136.77.158227.136.77.1592
105227.136.77.160/30227.136.77.161 to 227.136.77.162227.136.77.1632
106227.136.77.164/30227.136.77.165 to 227.136.77.166227.136.77.1672
107227.136.77.168/30227.136.77.169 to 227.136.77.170227.136.77.1712
108227.136.77.172/30227.136.77.173 to 227.136.77.174227.136.77.1752
109227.136.77.176/30227.136.77.177 to 227.136.77.178227.136.77.1792
110227.136.77.180/30227.136.77.181 to 227.136.77.182227.136.77.1832
111227.136.77.184/30227.136.77.185 to 227.136.77.186227.136.77.1872
112227.136.77.188/30227.136.77.189 to 227.136.77.190227.136.77.1912
113227.136.77.192/30227.136.77.193 to 227.136.77.194227.136.77.1952
114227.136.77.196/30227.136.77.197 to 227.136.77.198227.136.77.1992
115227.136.77.200/30227.136.77.201 to 227.136.77.202227.136.77.2032
116227.136.77.204/30227.136.77.205 to 227.136.77.206227.136.77.2072
117227.136.77.208/30227.136.77.209 to 227.136.77.210227.136.77.2112
118227.136.77.212/30227.136.77.213 to 227.136.77.214227.136.77.2152
119227.136.77.216/30227.136.77.217 to 227.136.77.218227.136.77.2192
120227.136.77.220/30227.136.77.221 to 227.136.77.222227.136.77.2232
121227.136.77.224/30227.136.77.225 to 227.136.77.226227.136.77.2272
122227.136.77.228/30227.136.77.229 to 227.136.77.230227.136.77.2312
123227.136.77.232/30227.136.77.233 to 227.136.77.234227.136.77.2352
124227.136.77.236/30227.136.77.237 to 227.136.77.238227.136.77.2392
125227.136.77.240/30227.136.77.241 to 227.136.77.242227.136.77.2432
126227.136.77.244/30227.136.77.245 to 227.136.77.246227.136.77.2472
127227.136.77.248/30227.136.77.249 to 227.136.77.250227.136.77.2512
128227.136.77.252/30227.136.77.253 to 227.136.77.254227.136.77.2552

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.