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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.

Network230.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
230.0.0.0
Broadcast address
230.255.255.255
First usable
230.0.0.1
Last usable
230.255.255.254
Usable hosts
16,777,214 (16,777,216 less the network and broadcast addresses)
Subnet mask
255.0.0.0
Wildcard mask
0.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/8
Type
Multicast 224.0.0.0/4
One-to-many traffic, such as IPTV and routing protocols
Old class
D (multicast)
As numbers
Hex E6000000 · Integer 3858759680 to 3875536895
Reverse DNS zone
230.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11100110..00000000.00000000.00000000230.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network11100110..00000000.00000000.00000000230.0.0.0
Broadcast11100110..11111111.11111111.11111111230.255.255.255
Split into smaller subnets/15
/9 (2)/10 (4)/11 (8)/12 (16)/13 (32)/14 (64)/15 (128)/16 (256)/17 (512)/18 (1,024)/19 (2,048)/20 (4,096)

230.0.0.0/8 makes 128 subnets of /15.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1230.0.0.0/15230.0.0.1 to 230.1.255.254230.1.255.255131,070
2230.2.0.0/15230.2.0.1 to 230.3.255.254230.3.255.255131,070
3230.4.0.0/15230.4.0.1 to 230.5.255.254230.5.255.255131,070
4230.6.0.0/15230.6.0.1 to 230.7.255.254230.7.255.255131,070
5230.8.0.0/15230.8.0.1 to 230.9.255.254230.9.255.255131,070
6230.10.0.0/15230.10.0.1 to 230.11.255.254230.11.255.255131,070
7230.12.0.0/15230.12.0.1 to 230.13.255.254230.13.255.255131,070
8230.14.0.0/15230.14.0.1 to 230.15.255.254230.15.255.255131,070
9230.16.0.0/15230.16.0.1 to 230.17.255.254230.17.255.255131,070
10230.18.0.0/15230.18.0.1 to 230.19.255.254230.19.255.255131,070
11230.20.0.0/15230.20.0.1 to 230.21.255.254230.21.255.255131,070
12230.22.0.0/15230.22.0.1 to 230.23.255.254230.23.255.255131,070
13230.24.0.0/15230.24.0.1 to 230.25.255.254230.25.255.255131,070
14230.26.0.0/15230.26.0.1 to 230.27.255.254230.27.255.255131,070
15230.28.0.0/15230.28.0.1 to 230.29.255.254230.29.255.255131,070
16230.30.0.0/15230.30.0.1 to 230.31.255.254230.31.255.255131,070
17230.32.0.0/15230.32.0.1 to 230.33.255.254230.33.255.255131,070
18230.34.0.0/15230.34.0.1 to 230.35.255.254230.35.255.255131,070
19230.36.0.0/15230.36.0.1 to 230.37.255.254230.37.255.255131,070
20230.38.0.0/15230.38.0.1 to 230.39.255.254230.39.255.255131,070
21230.40.0.0/15230.40.0.1 to 230.41.255.254230.41.255.255131,070
22230.42.0.0/15230.42.0.1 to 230.43.255.254230.43.255.255131,070
23230.44.0.0/15230.44.0.1 to 230.45.255.254230.45.255.255131,070
24230.46.0.0/15230.46.0.1 to 230.47.255.254230.47.255.255131,070
25230.48.0.0/15230.48.0.1 to 230.49.255.254230.49.255.255131,070
26230.50.0.0/15230.50.0.1 to 230.51.255.254230.51.255.255131,070
27230.52.0.0/15230.52.0.1 to 230.53.255.254230.53.255.255131,070
28230.54.0.0/15230.54.0.1 to 230.55.255.254230.55.255.255131,070
29230.56.0.0/15230.56.0.1 to 230.57.255.254230.57.255.255131,070
30230.58.0.0/15230.58.0.1 to 230.59.255.254230.59.255.255131,070
31230.60.0.0/15230.60.0.1 to 230.61.255.254230.61.255.255131,070
32230.62.0.0/15230.62.0.1 to 230.63.255.254230.63.255.255131,070
33230.64.0.0/15230.64.0.1 to 230.65.255.254230.65.255.255131,070
34230.66.0.0/15230.66.0.1 to 230.67.255.254230.67.255.255131,070
35230.68.0.0/15230.68.0.1 to 230.69.255.254230.69.255.255131,070
36230.70.0.0/15230.70.0.1 to 230.71.255.254230.71.255.255131,070
37230.72.0.0/15230.72.0.1 to 230.73.255.254230.73.255.255131,070
38230.74.0.0/15230.74.0.1 to 230.75.255.254230.75.255.255131,070
39230.76.0.0/15230.76.0.1 to 230.77.255.254230.77.255.255131,070
40230.78.0.0/15230.78.0.1 to 230.79.255.254230.79.255.255131,070
41230.80.0.0/15230.80.0.1 to 230.81.255.254230.81.255.255131,070
42230.82.0.0/15230.82.0.1 to 230.83.255.254230.83.255.255131,070
43230.84.0.0/15230.84.0.1 to 230.85.255.254230.85.255.255131,070
44230.86.0.0/15230.86.0.1 to 230.87.255.254230.87.255.255131,070
45230.88.0.0/15230.88.0.1 to 230.89.255.254230.89.255.255131,070
46230.90.0.0/15230.90.0.1 to 230.91.255.254230.91.255.255131,070
47230.92.0.0/15230.92.0.1 to 230.93.255.254230.93.255.255131,070
48230.94.0.0/15230.94.0.1 to 230.95.255.254230.95.255.255131,070
49230.96.0.0/15230.96.0.1 to 230.97.255.254230.97.255.255131,070
50230.98.0.0/15230.98.0.1 to 230.99.255.254230.99.255.255131,070
51230.100.0.0/15230.100.0.1 to 230.101.255.254230.101.255.255131,070
52230.102.0.0/15230.102.0.1 to 230.103.255.254230.103.255.255131,070
53230.104.0.0/15230.104.0.1 to 230.105.255.254230.105.255.255131,070
54230.106.0.0/15230.106.0.1 to 230.107.255.254230.107.255.255131,070
55230.108.0.0/15230.108.0.1 to 230.109.255.254230.109.255.255131,070
56230.110.0.0/15230.110.0.1 to 230.111.255.254230.111.255.255131,070
57230.112.0.0/15230.112.0.1 to 230.113.255.254230.113.255.255131,070
58230.114.0.0/15230.114.0.1 to 230.115.255.254230.115.255.255131,070
59230.116.0.0/15230.116.0.1 to 230.117.255.254230.117.255.255131,070
60230.118.0.0/15230.118.0.1 to 230.119.255.254230.119.255.255131,070
61230.120.0.0/15230.120.0.1 to 230.121.255.254230.121.255.255131,070
62230.122.0.0/15230.122.0.1 to 230.123.255.254230.123.255.255131,070
63230.124.0.0/15230.124.0.1 to 230.125.255.254230.125.255.255131,070
64230.126.0.0/15230.126.0.1 to 230.127.255.254230.127.255.255131,070
65230.128.0.0/15230.128.0.1 to 230.129.255.254230.129.255.255131,070
66230.130.0.0/15230.130.0.1 to 230.131.255.254230.131.255.255131,070
67230.132.0.0/15230.132.0.1 to 230.133.255.254230.133.255.255131,070
68230.134.0.0/15230.134.0.1 to 230.135.255.254230.135.255.255131,070
69230.136.0.0/15230.136.0.1 to 230.137.255.254230.137.255.255131,070
70230.138.0.0/15230.138.0.1 to 230.139.255.254230.139.255.255131,070
71230.140.0.0/15230.140.0.1 to 230.141.255.254230.141.255.255131,070
72230.142.0.0/15230.142.0.1 to 230.143.255.254230.143.255.255131,070
73230.144.0.0/15230.144.0.1 to 230.145.255.254230.145.255.255131,070
74230.146.0.0/15230.146.0.1 to 230.147.255.254230.147.255.255131,070
75230.148.0.0/15230.148.0.1 to 230.149.255.254230.149.255.255131,070
76230.150.0.0/15230.150.0.1 to 230.151.255.254230.151.255.255131,070
77230.152.0.0/15230.152.0.1 to 230.153.255.254230.153.255.255131,070
78230.154.0.0/15230.154.0.1 to 230.155.255.254230.155.255.255131,070
79230.156.0.0/15230.156.0.1 to 230.157.255.254230.157.255.255131,070
80230.158.0.0/15230.158.0.1 to 230.159.255.254230.159.255.255131,070
81230.160.0.0/15230.160.0.1 to 230.161.255.254230.161.255.255131,070
82230.162.0.0/15230.162.0.1 to 230.163.255.254230.163.255.255131,070
83230.164.0.0/15230.164.0.1 to 230.165.255.254230.165.255.255131,070
84230.166.0.0/15230.166.0.1 to 230.167.255.254230.167.255.255131,070
85230.168.0.0/15230.168.0.1 to 230.169.255.254230.169.255.255131,070
86230.170.0.0/15230.170.0.1 to 230.171.255.254230.171.255.255131,070
87230.172.0.0/15230.172.0.1 to 230.173.255.254230.173.255.255131,070
88230.174.0.0/15230.174.0.1 to 230.175.255.254230.175.255.255131,070
89230.176.0.0/15230.176.0.1 to 230.177.255.254230.177.255.255131,070
90230.178.0.0/15230.178.0.1 to 230.179.255.254230.179.255.255131,070
91230.180.0.0/15230.180.0.1 to 230.181.255.254230.181.255.255131,070
92230.182.0.0/15230.182.0.1 to 230.183.255.254230.183.255.255131,070
93230.184.0.0/15230.184.0.1 to 230.185.255.254230.185.255.255131,070
94230.186.0.0/15230.186.0.1 to 230.187.255.254230.187.255.255131,070
95230.188.0.0/15230.188.0.1 to 230.189.255.254230.189.255.255131,070
96230.190.0.0/15230.190.0.1 to 230.191.255.254230.191.255.255131,070
97230.192.0.0/15230.192.0.1 to 230.193.255.254230.193.255.255131,070
98230.194.0.0/15230.194.0.1 to 230.195.255.254230.195.255.255131,070
99230.196.0.0/15230.196.0.1 to 230.197.255.254230.197.255.255131,070
100230.198.0.0/15230.198.0.1 to 230.199.255.254230.199.255.255131,070
101230.200.0.0/15230.200.0.1 to 230.201.255.254230.201.255.255131,070
102230.202.0.0/15230.202.0.1 to 230.203.255.254230.203.255.255131,070
103230.204.0.0/15230.204.0.1 to 230.205.255.254230.205.255.255131,070
104230.206.0.0/15230.206.0.1 to 230.207.255.254230.207.255.255131,070
105230.208.0.0/15230.208.0.1 to 230.209.255.254230.209.255.255131,070
106230.210.0.0/15230.210.0.1 to 230.211.255.254230.211.255.255131,070
107230.212.0.0/15230.212.0.1 to 230.213.255.254230.213.255.255131,070
108230.214.0.0/15230.214.0.1 to 230.215.255.254230.215.255.255131,070
109230.216.0.0/15230.216.0.1 to 230.217.255.254230.217.255.255131,070
110230.218.0.0/15230.218.0.1 to 230.219.255.254230.219.255.255131,070
111230.220.0.0/15230.220.0.1 to 230.221.255.254230.221.255.255131,070
112230.222.0.0/15230.222.0.1 to 230.223.255.254230.223.255.255131,070
113230.224.0.0/15230.224.0.1 to 230.225.255.254230.225.255.255131,070
114230.226.0.0/15230.226.0.1 to 230.227.255.254230.227.255.255131,070
115230.228.0.0/15230.228.0.1 to 230.229.255.254230.229.255.255131,070
116230.230.0.0/15230.230.0.1 to 230.231.255.254230.231.255.255131,070
117230.232.0.0/15230.232.0.1 to 230.233.255.254230.233.255.255131,070
118230.234.0.0/15230.234.0.1 to 230.235.255.254230.235.255.255131,070
119230.236.0.0/15230.236.0.1 to 230.237.255.254230.237.255.255131,070
120230.238.0.0/15230.238.0.1 to 230.239.255.254230.239.255.255131,070
121230.240.0.0/15230.240.0.1 to 230.241.255.254230.241.255.255131,070
122230.242.0.0/15230.242.0.1 to 230.243.255.254230.243.255.255131,070
123230.244.0.0/15230.244.0.1 to 230.245.255.254230.245.255.255131,070
124230.246.0.0/15230.246.0.1 to 230.247.255.254230.247.255.255131,070
125230.248.0.0/15230.248.0.1 to 230.249.255.254230.249.255.255131,070
126230.250.0.0/15230.250.0.1 to 230.251.255.254230.251.255.255131,070
127230.252.0.0/15230.252.0.1 to 230.253.255.254230.253.255.255131,070
128230.254.0.0/15230.254.0.1 to 230.255.255.254230.255.255.255131,070

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.