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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.

Network253.0.0.0/8
Usable hosts16,777,214
Subnet mask255.0.0.0
Addresses16,777,216
Network address
253.0.0.0
Broadcast address
253.255.255.255
First usable
253.0.0.1
Last usable
253.255.255.254
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
Reserved 240.0.0.0/4
Future use; not usable on most systems
Old class
E (reserved)
As numbers
Hex FD000000 · Integer 4244635648 to 4261412863
Reverse DNS zone
253.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11111101..00000000.00000000.00000000253.0.0.0
Subnet mask11111111..00000000.00000000.00000000255.0.0.0
Network11111101..00000000.00000000.00000000253.0.0.0
Broadcast11111101..11111111.11111111.11111111253.255.255.255
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)

253.0.0.0/8 makes 128 subnets of /15.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1253.0.0.0/15253.0.0.1 to 253.1.255.254253.1.255.255131,070
2253.2.0.0/15253.2.0.1 to 253.3.255.254253.3.255.255131,070
3253.4.0.0/15253.4.0.1 to 253.5.255.254253.5.255.255131,070
4253.6.0.0/15253.6.0.1 to 253.7.255.254253.7.255.255131,070
5253.8.0.0/15253.8.0.1 to 253.9.255.254253.9.255.255131,070
6253.10.0.0/15253.10.0.1 to 253.11.255.254253.11.255.255131,070
7253.12.0.0/15253.12.0.1 to 253.13.255.254253.13.255.255131,070
8253.14.0.0/15253.14.0.1 to 253.15.255.254253.15.255.255131,070
9253.16.0.0/15253.16.0.1 to 253.17.255.254253.17.255.255131,070
10253.18.0.0/15253.18.0.1 to 253.19.255.254253.19.255.255131,070
11253.20.0.0/15253.20.0.1 to 253.21.255.254253.21.255.255131,070
12253.22.0.0/15253.22.0.1 to 253.23.255.254253.23.255.255131,070
13253.24.0.0/15253.24.0.1 to 253.25.255.254253.25.255.255131,070
14253.26.0.0/15253.26.0.1 to 253.27.255.254253.27.255.255131,070
15253.28.0.0/15253.28.0.1 to 253.29.255.254253.29.255.255131,070
16253.30.0.0/15253.30.0.1 to 253.31.255.254253.31.255.255131,070
17253.32.0.0/15253.32.0.1 to 253.33.255.254253.33.255.255131,070
18253.34.0.0/15253.34.0.1 to 253.35.255.254253.35.255.255131,070
19253.36.0.0/15253.36.0.1 to 253.37.255.254253.37.255.255131,070
20253.38.0.0/15253.38.0.1 to 253.39.255.254253.39.255.255131,070
21253.40.0.0/15253.40.0.1 to 253.41.255.254253.41.255.255131,070
22253.42.0.0/15253.42.0.1 to 253.43.255.254253.43.255.255131,070
23253.44.0.0/15253.44.0.1 to 253.45.255.254253.45.255.255131,070
24253.46.0.0/15253.46.0.1 to 253.47.255.254253.47.255.255131,070
25253.48.0.0/15253.48.0.1 to 253.49.255.254253.49.255.255131,070
26253.50.0.0/15253.50.0.1 to 253.51.255.254253.51.255.255131,070
27253.52.0.0/15253.52.0.1 to 253.53.255.254253.53.255.255131,070
28253.54.0.0/15253.54.0.1 to 253.55.255.254253.55.255.255131,070
29253.56.0.0/15253.56.0.1 to 253.57.255.254253.57.255.255131,070
30253.58.0.0/15253.58.0.1 to 253.59.255.254253.59.255.255131,070
31253.60.0.0/15253.60.0.1 to 253.61.255.254253.61.255.255131,070
32253.62.0.0/15253.62.0.1 to 253.63.255.254253.63.255.255131,070
33253.64.0.0/15253.64.0.1 to 253.65.255.254253.65.255.255131,070
34253.66.0.0/15253.66.0.1 to 253.67.255.254253.67.255.255131,070
35253.68.0.0/15253.68.0.1 to 253.69.255.254253.69.255.255131,070
36253.70.0.0/15253.70.0.1 to 253.71.255.254253.71.255.255131,070
37253.72.0.0/15253.72.0.1 to 253.73.255.254253.73.255.255131,070
38253.74.0.0/15253.74.0.1 to 253.75.255.254253.75.255.255131,070
39253.76.0.0/15253.76.0.1 to 253.77.255.254253.77.255.255131,070
40253.78.0.0/15253.78.0.1 to 253.79.255.254253.79.255.255131,070
41253.80.0.0/15253.80.0.1 to 253.81.255.254253.81.255.255131,070
42253.82.0.0/15253.82.0.1 to 253.83.255.254253.83.255.255131,070
43253.84.0.0/15253.84.0.1 to 253.85.255.254253.85.255.255131,070
44253.86.0.0/15253.86.0.1 to 253.87.255.254253.87.255.255131,070
45253.88.0.0/15253.88.0.1 to 253.89.255.254253.89.255.255131,070
46253.90.0.0/15253.90.0.1 to 253.91.255.254253.91.255.255131,070
47253.92.0.0/15253.92.0.1 to 253.93.255.254253.93.255.255131,070
48253.94.0.0/15253.94.0.1 to 253.95.255.254253.95.255.255131,070
49253.96.0.0/15253.96.0.1 to 253.97.255.254253.97.255.255131,070
50253.98.0.0/15253.98.0.1 to 253.99.255.254253.99.255.255131,070
51253.100.0.0/15253.100.0.1 to 253.101.255.254253.101.255.255131,070
52253.102.0.0/15253.102.0.1 to 253.103.255.254253.103.255.255131,070
53253.104.0.0/15253.104.0.1 to 253.105.255.254253.105.255.255131,070
54253.106.0.0/15253.106.0.1 to 253.107.255.254253.107.255.255131,070
55253.108.0.0/15253.108.0.1 to 253.109.255.254253.109.255.255131,070
56253.110.0.0/15253.110.0.1 to 253.111.255.254253.111.255.255131,070
57253.112.0.0/15253.112.0.1 to 253.113.255.254253.113.255.255131,070
58253.114.0.0/15253.114.0.1 to 253.115.255.254253.115.255.255131,070
59253.116.0.0/15253.116.0.1 to 253.117.255.254253.117.255.255131,070
60253.118.0.0/15253.118.0.1 to 253.119.255.254253.119.255.255131,070
61253.120.0.0/15253.120.0.1 to 253.121.255.254253.121.255.255131,070
62253.122.0.0/15253.122.0.1 to 253.123.255.254253.123.255.255131,070
63253.124.0.0/15253.124.0.1 to 253.125.255.254253.125.255.255131,070
64253.126.0.0/15253.126.0.1 to 253.127.255.254253.127.255.255131,070
65253.128.0.0/15253.128.0.1 to 253.129.255.254253.129.255.255131,070
66253.130.0.0/15253.130.0.1 to 253.131.255.254253.131.255.255131,070
67253.132.0.0/15253.132.0.1 to 253.133.255.254253.133.255.255131,070
68253.134.0.0/15253.134.0.1 to 253.135.255.254253.135.255.255131,070
69253.136.0.0/15253.136.0.1 to 253.137.255.254253.137.255.255131,070
70253.138.0.0/15253.138.0.1 to 253.139.255.254253.139.255.255131,070
71253.140.0.0/15253.140.0.1 to 253.141.255.254253.141.255.255131,070
72253.142.0.0/15253.142.0.1 to 253.143.255.254253.143.255.255131,070
73253.144.0.0/15253.144.0.1 to 253.145.255.254253.145.255.255131,070
74253.146.0.0/15253.146.0.1 to 253.147.255.254253.147.255.255131,070
75253.148.0.0/15253.148.0.1 to 253.149.255.254253.149.255.255131,070
76253.150.0.0/15253.150.0.1 to 253.151.255.254253.151.255.255131,070
77253.152.0.0/15253.152.0.1 to 253.153.255.254253.153.255.255131,070
78253.154.0.0/15253.154.0.1 to 253.155.255.254253.155.255.255131,070
79253.156.0.0/15253.156.0.1 to 253.157.255.254253.157.255.255131,070
80253.158.0.0/15253.158.0.1 to 253.159.255.254253.159.255.255131,070
81253.160.0.0/15253.160.0.1 to 253.161.255.254253.161.255.255131,070
82253.162.0.0/15253.162.0.1 to 253.163.255.254253.163.255.255131,070
83253.164.0.0/15253.164.0.1 to 253.165.255.254253.165.255.255131,070
84253.166.0.0/15253.166.0.1 to 253.167.255.254253.167.255.255131,070
85253.168.0.0/15253.168.0.1 to 253.169.255.254253.169.255.255131,070
86253.170.0.0/15253.170.0.1 to 253.171.255.254253.171.255.255131,070
87253.172.0.0/15253.172.0.1 to 253.173.255.254253.173.255.255131,070
88253.174.0.0/15253.174.0.1 to 253.175.255.254253.175.255.255131,070
89253.176.0.0/15253.176.0.1 to 253.177.255.254253.177.255.255131,070
90253.178.0.0/15253.178.0.1 to 253.179.255.254253.179.255.255131,070
91253.180.0.0/15253.180.0.1 to 253.181.255.254253.181.255.255131,070
92253.182.0.0/15253.182.0.1 to 253.183.255.254253.183.255.255131,070
93253.184.0.0/15253.184.0.1 to 253.185.255.254253.185.255.255131,070
94253.186.0.0/15253.186.0.1 to 253.187.255.254253.187.255.255131,070
95253.188.0.0/15253.188.0.1 to 253.189.255.254253.189.255.255131,070
96253.190.0.0/15253.190.0.1 to 253.191.255.254253.191.255.255131,070
97253.192.0.0/15253.192.0.1 to 253.193.255.254253.193.255.255131,070
98253.194.0.0/15253.194.0.1 to 253.195.255.254253.195.255.255131,070
99253.196.0.0/15253.196.0.1 to 253.197.255.254253.197.255.255131,070
100253.198.0.0/15253.198.0.1 to 253.199.255.254253.199.255.255131,070
101253.200.0.0/15253.200.0.1 to 253.201.255.254253.201.255.255131,070
102253.202.0.0/15253.202.0.1 to 253.203.255.254253.203.255.255131,070
103253.204.0.0/15253.204.0.1 to 253.205.255.254253.205.255.255131,070
104253.206.0.0/15253.206.0.1 to 253.207.255.254253.207.255.255131,070
105253.208.0.0/15253.208.0.1 to 253.209.255.254253.209.255.255131,070
106253.210.0.0/15253.210.0.1 to 253.211.255.254253.211.255.255131,070
107253.212.0.0/15253.212.0.1 to 253.213.255.254253.213.255.255131,070
108253.214.0.0/15253.214.0.1 to 253.215.255.254253.215.255.255131,070
109253.216.0.0/15253.216.0.1 to 253.217.255.254253.217.255.255131,070
110253.218.0.0/15253.218.0.1 to 253.219.255.254253.219.255.255131,070
111253.220.0.0/15253.220.0.1 to 253.221.255.254253.221.255.255131,070
112253.222.0.0/15253.222.0.1 to 253.223.255.254253.223.255.255131,070
113253.224.0.0/15253.224.0.1 to 253.225.255.254253.225.255.255131,070
114253.226.0.0/15253.226.0.1 to 253.227.255.254253.227.255.255131,070
115253.228.0.0/15253.228.0.1 to 253.229.255.254253.229.255.255131,070
116253.230.0.0/15253.230.0.1 to 253.231.255.254253.231.255.255131,070
117253.232.0.0/15253.232.0.1 to 253.233.255.254253.233.255.255131,070
118253.234.0.0/15253.234.0.1 to 253.235.255.254253.235.255.255131,070
119253.236.0.0/15253.236.0.1 to 253.237.255.254253.237.255.255131,070
120253.238.0.0/15253.238.0.1 to 253.239.255.254253.239.255.255131,070
121253.240.0.0/15253.240.0.1 to 253.241.255.254253.241.255.255131,070
122253.242.0.0/15253.242.0.1 to 253.243.255.254253.243.255.255131,070
123253.244.0.0/15253.244.0.1 to 253.245.255.254253.245.255.255131,070
124253.246.0.0/15253.246.0.1 to 253.247.255.254253.247.255.255131,070
125253.248.0.0/15253.248.0.1 to 253.249.255.254253.249.255.255131,070
126253.250.0.0/15253.250.0.1 to 253.251.255.254253.251.255.255131,070
127253.252.0.0/15253.252.0.1 to 253.253.255.254253.253.255.255131,070
128253.254.0.0/15253.254.0.1 to 253.255.255.254253.255.255.255131,070

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.