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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.

Network253.0.0.0/9
Usable hosts8,388,606
Subnet mask255.128.0.0
Addresses8,388,608
Network address
253.0.0.0
Broadcast address
253.127.255.255
First usable
253.0.0.1
Last usable
253.127.255.254
Usable hosts
8,388,606 (8,388,608 less the network and broadcast addresses)
Subnet mask
255.128.0.0
Wildcard mask
0.127.255.255 (Cisco ACLs, OSPF)
Prefix length
/9
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 4253024255
Reverse DNS zones
0.253.in-addr.arpa
1.253.in-addr.arpa
2.253.in-addr.arpa
3.253.in-addr.arpa
4.253.in-addr.arpa
5.253.in-addr.arpa
6.253.in-addr.arpa
7.253.in-addr.arpa
8.253.in-addr.arpa
9.253.in-addr.arpa
10.253.in-addr.arpa
11.253.in-addr.arpa
12.253.in-addr.arpa
13.253.in-addr.arpa
14.253.in-addr.arpa
15.253.in-addr.arpa
and 112 more
/9 is not on a 8-bit boundary, so it takes 128 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11111101.00000000.00000000.00000000253.0.0.0
Subnet mask11111111.10000000.00000000.00000000255.128.0.0
Network11111101.00000000.00000000.00000000253.0.0.0
Broadcast11111101.01111111.11111111.11111111253.127.255.255
Split into smaller subnets/16
/10 (2)/11 (4)/12 (8)/13 (16)/14 (32)/15 (64)/16 (128)/17 (256)/18 (512)/19 (1,024)/20 (2,048)/21 (4,096)

253.0.0.0/9 makes 128 subnets of /16.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1253.0.0.0/16253.0.0.1 to 253.0.255.254253.0.255.25565,534
2253.1.0.0/16253.1.0.1 to 253.1.255.254253.1.255.25565,534
3253.2.0.0/16253.2.0.1 to 253.2.255.254253.2.255.25565,534
4253.3.0.0/16253.3.0.1 to 253.3.255.254253.3.255.25565,534
5253.4.0.0/16253.4.0.1 to 253.4.255.254253.4.255.25565,534
6253.5.0.0/16253.5.0.1 to 253.5.255.254253.5.255.25565,534
7253.6.0.0/16253.6.0.1 to 253.6.255.254253.6.255.25565,534
8253.7.0.0/16253.7.0.1 to 253.7.255.254253.7.255.25565,534
9253.8.0.0/16253.8.0.1 to 253.8.255.254253.8.255.25565,534
10253.9.0.0/16253.9.0.1 to 253.9.255.254253.9.255.25565,534
11253.10.0.0/16253.10.0.1 to 253.10.255.254253.10.255.25565,534
12253.11.0.0/16253.11.0.1 to 253.11.255.254253.11.255.25565,534
13253.12.0.0/16253.12.0.1 to 253.12.255.254253.12.255.25565,534
14253.13.0.0/16253.13.0.1 to 253.13.255.254253.13.255.25565,534
15253.14.0.0/16253.14.0.1 to 253.14.255.254253.14.255.25565,534
16253.15.0.0/16253.15.0.1 to 253.15.255.254253.15.255.25565,534
17253.16.0.0/16253.16.0.1 to 253.16.255.254253.16.255.25565,534
18253.17.0.0/16253.17.0.1 to 253.17.255.254253.17.255.25565,534
19253.18.0.0/16253.18.0.1 to 253.18.255.254253.18.255.25565,534
20253.19.0.0/16253.19.0.1 to 253.19.255.254253.19.255.25565,534
21253.20.0.0/16253.20.0.1 to 253.20.255.254253.20.255.25565,534
22253.21.0.0/16253.21.0.1 to 253.21.255.254253.21.255.25565,534
23253.22.0.0/16253.22.0.1 to 253.22.255.254253.22.255.25565,534
24253.23.0.0/16253.23.0.1 to 253.23.255.254253.23.255.25565,534
25253.24.0.0/16253.24.0.1 to 253.24.255.254253.24.255.25565,534
26253.25.0.0/16253.25.0.1 to 253.25.255.254253.25.255.25565,534
27253.26.0.0/16253.26.0.1 to 253.26.255.254253.26.255.25565,534
28253.27.0.0/16253.27.0.1 to 253.27.255.254253.27.255.25565,534
29253.28.0.0/16253.28.0.1 to 253.28.255.254253.28.255.25565,534
30253.29.0.0/16253.29.0.1 to 253.29.255.254253.29.255.25565,534
31253.30.0.0/16253.30.0.1 to 253.30.255.254253.30.255.25565,534
32253.31.0.0/16253.31.0.1 to 253.31.255.254253.31.255.25565,534
33253.32.0.0/16253.32.0.1 to 253.32.255.254253.32.255.25565,534
34253.33.0.0/16253.33.0.1 to 253.33.255.254253.33.255.25565,534
35253.34.0.0/16253.34.0.1 to 253.34.255.254253.34.255.25565,534
36253.35.0.0/16253.35.0.1 to 253.35.255.254253.35.255.25565,534
37253.36.0.0/16253.36.0.1 to 253.36.255.254253.36.255.25565,534
38253.37.0.0/16253.37.0.1 to 253.37.255.254253.37.255.25565,534
39253.38.0.0/16253.38.0.1 to 253.38.255.254253.38.255.25565,534
40253.39.0.0/16253.39.0.1 to 253.39.255.254253.39.255.25565,534
41253.40.0.0/16253.40.0.1 to 253.40.255.254253.40.255.25565,534
42253.41.0.0/16253.41.0.1 to 253.41.255.254253.41.255.25565,534
43253.42.0.0/16253.42.0.1 to 253.42.255.254253.42.255.25565,534
44253.43.0.0/16253.43.0.1 to 253.43.255.254253.43.255.25565,534
45253.44.0.0/16253.44.0.1 to 253.44.255.254253.44.255.25565,534
46253.45.0.0/16253.45.0.1 to 253.45.255.254253.45.255.25565,534
47253.46.0.0/16253.46.0.1 to 253.46.255.254253.46.255.25565,534
48253.47.0.0/16253.47.0.1 to 253.47.255.254253.47.255.25565,534
49253.48.0.0/16253.48.0.1 to 253.48.255.254253.48.255.25565,534
50253.49.0.0/16253.49.0.1 to 253.49.255.254253.49.255.25565,534
51253.50.0.0/16253.50.0.1 to 253.50.255.254253.50.255.25565,534
52253.51.0.0/16253.51.0.1 to 253.51.255.254253.51.255.25565,534
53253.52.0.0/16253.52.0.1 to 253.52.255.254253.52.255.25565,534
54253.53.0.0/16253.53.0.1 to 253.53.255.254253.53.255.25565,534
55253.54.0.0/16253.54.0.1 to 253.54.255.254253.54.255.25565,534
56253.55.0.0/16253.55.0.1 to 253.55.255.254253.55.255.25565,534
57253.56.0.0/16253.56.0.1 to 253.56.255.254253.56.255.25565,534
58253.57.0.0/16253.57.0.1 to 253.57.255.254253.57.255.25565,534
59253.58.0.0/16253.58.0.1 to 253.58.255.254253.58.255.25565,534
60253.59.0.0/16253.59.0.1 to 253.59.255.254253.59.255.25565,534
61253.60.0.0/16253.60.0.1 to 253.60.255.254253.60.255.25565,534
62253.61.0.0/16253.61.0.1 to 253.61.255.254253.61.255.25565,534
63253.62.0.0/16253.62.0.1 to 253.62.255.254253.62.255.25565,534
64253.63.0.0/16253.63.0.1 to 253.63.255.254253.63.255.25565,534
65253.64.0.0/16253.64.0.1 to 253.64.255.254253.64.255.25565,534
66253.65.0.0/16253.65.0.1 to 253.65.255.254253.65.255.25565,534
67253.66.0.0/16253.66.0.1 to 253.66.255.254253.66.255.25565,534
68253.67.0.0/16253.67.0.1 to 253.67.255.254253.67.255.25565,534
69253.68.0.0/16253.68.0.1 to 253.68.255.254253.68.255.25565,534
70253.69.0.0/16253.69.0.1 to 253.69.255.254253.69.255.25565,534
71253.70.0.0/16253.70.0.1 to 253.70.255.254253.70.255.25565,534
72253.71.0.0/16253.71.0.1 to 253.71.255.254253.71.255.25565,534
73253.72.0.0/16253.72.0.1 to 253.72.255.254253.72.255.25565,534
74253.73.0.0/16253.73.0.1 to 253.73.255.254253.73.255.25565,534
75253.74.0.0/16253.74.0.1 to 253.74.255.254253.74.255.25565,534
76253.75.0.0/16253.75.0.1 to 253.75.255.254253.75.255.25565,534
77253.76.0.0/16253.76.0.1 to 253.76.255.254253.76.255.25565,534
78253.77.0.0/16253.77.0.1 to 253.77.255.254253.77.255.25565,534
79253.78.0.0/16253.78.0.1 to 253.78.255.254253.78.255.25565,534
80253.79.0.0/16253.79.0.1 to 253.79.255.254253.79.255.25565,534
81253.80.0.0/16253.80.0.1 to 253.80.255.254253.80.255.25565,534
82253.81.0.0/16253.81.0.1 to 253.81.255.254253.81.255.25565,534
83253.82.0.0/16253.82.0.1 to 253.82.255.254253.82.255.25565,534
84253.83.0.0/16253.83.0.1 to 253.83.255.254253.83.255.25565,534
85253.84.0.0/16253.84.0.1 to 253.84.255.254253.84.255.25565,534
86253.85.0.0/16253.85.0.1 to 253.85.255.254253.85.255.25565,534
87253.86.0.0/16253.86.0.1 to 253.86.255.254253.86.255.25565,534
88253.87.0.0/16253.87.0.1 to 253.87.255.254253.87.255.25565,534
89253.88.0.0/16253.88.0.1 to 253.88.255.254253.88.255.25565,534
90253.89.0.0/16253.89.0.1 to 253.89.255.254253.89.255.25565,534
91253.90.0.0/16253.90.0.1 to 253.90.255.254253.90.255.25565,534
92253.91.0.0/16253.91.0.1 to 253.91.255.254253.91.255.25565,534
93253.92.0.0/16253.92.0.1 to 253.92.255.254253.92.255.25565,534
94253.93.0.0/16253.93.0.1 to 253.93.255.254253.93.255.25565,534
95253.94.0.0/16253.94.0.1 to 253.94.255.254253.94.255.25565,534
96253.95.0.0/16253.95.0.1 to 253.95.255.254253.95.255.25565,534
97253.96.0.0/16253.96.0.1 to 253.96.255.254253.96.255.25565,534
98253.97.0.0/16253.97.0.1 to 253.97.255.254253.97.255.25565,534
99253.98.0.0/16253.98.0.1 to 253.98.255.254253.98.255.25565,534
100253.99.0.0/16253.99.0.1 to 253.99.255.254253.99.255.25565,534
101253.100.0.0/16253.100.0.1 to 253.100.255.254253.100.255.25565,534
102253.101.0.0/16253.101.0.1 to 253.101.255.254253.101.255.25565,534
103253.102.0.0/16253.102.0.1 to 253.102.255.254253.102.255.25565,534
104253.103.0.0/16253.103.0.1 to 253.103.255.254253.103.255.25565,534
105253.104.0.0/16253.104.0.1 to 253.104.255.254253.104.255.25565,534
106253.105.0.0/16253.105.0.1 to 253.105.255.254253.105.255.25565,534
107253.106.0.0/16253.106.0.1 to 253.106.255.254253.106.255.25565,534
108253.107.0.0/16253.107.0.1 to 253.107.255.254253.107.255.25565,534
109253.108.0.0/16253.108.0.1 to 253.108.255.254253.108.255.25565,534
110253.109.0.0/16253.109.0.1 to 253.109.255.254253.109.255.25565,534
111253.110.0.0/16253.110.0.1 to 253.110.255.254253.110.255.25565,534
112253.111.0.0/16253.111.0.1 to 253.111.255.254253.111.255.25565,534
113253.112.0.0/16253.112.0.1 to 253.112.255.254253.112.255.25565,534
114253.113.0.0/16253.113.0.1 to 253.113.255.254253.113.255.25565,534
115253.114.0.0/16253.114.0.1 to 253.114.255.254253.114.255.25565,534
116253.115.0.0/16253.115.0.1 to 253.115.255.254253.115.255.25565,534
117253.116.0.0/16253.116.0.1 to 253.116.255.254253.116.255.25565,534
118253.117.0.0/16253.117.0.1 to 253.117.255.254253.117.255.25565,534
119253.118.0.0/16253.118.0.1 to 253.118.255.254253.118.255.25565,534
120253.119.0.0/16253.119.0.1 to 253.119.255.254253.119.255.25565,534
121253.120.0.0/16253.120.0.1 to 253.120.255.254253.120.255.25565,534
122253.121.0.0/16253.121.0.1 to 253.121.255.254253.121.255.25565,534
123253.122.0.0/16253.122.0.1 to 253.122.255.254253.122.255.25565,534
124253.123.0.0/16253.123.0.1 to 253.123.255.254253.123.255.25565,534
125253.124.0.0/16253.124.0.1 to 253.124.255.254253.124.255.25565,534
126253.125.0.0/16253.125.0.1 to 253.125.255.254253.125.255.25565,534
127253.126.0.0/16253.126.0.1 to 253.126.255.254253.126.255.25565,534
128253.127.0.0/16253.127.0.1 to 253.127.255.254253.127.255.25565,534

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.