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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.

Network225.0.0.0/9
Usable hosts8,388,606
Subnet mask255.128.0.0
Addresses8,388,608
Network address
225.0.0.0
Broadcast address
225.127.255.255
First usable
225.0.0.1
Last usable
225.127.255.254
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
Multicast 224.0.0.0/4
One-to-many traffic, such as IPTV and routing protocols
Old class
D (multicast)
As numbers
Hex E1000000 · Integer 3774873600 to 3783262207
Reverse DNS zones
0.225.in-addr.arpa
1.225.in-addr.arpa
2.225.in-addr.arpa
3.225.in-addr.arpa
4.225.in-addr.arpa
5.225.in-addr.arpa
6.225.in-addr.arpa
7.225.in-addr.arpa
8.225.in-addr.arpa
9.225.in-addr.arpa
10.225.in-addr.arpa
11.225.in-addr.arpa
12.225.in-addr.arpa
13.225.in-addr.arpa
14.225.in-addr.arpa
15.225.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
Address11100001.00000000.00000000.00000000225.0.0.0
Subnet mask11111111.10000000.00000000.00000000255.128.0.0
Network11100001.00000000.00000000.00000000225.0.0.0
Broadcast11100001.01111111.11111111.11111111225.127.255.255
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)

225.0.0.0/9 makes 128 subnets of /16.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1225.0.0.0/16225.0.0.1 to 225.0.255.254225.0.255.25565,534
2225.1.0.0/16225.1.0.1 to 225.1.255.254225.1.255.25565,534
3225.2.0.0/16225.2.0.1 to 225.2.255.254225.2.255.25565,534
4225.3.0.0/16225.3.0.1 to 225.3.255.254225.3.255.25565,534
5225.4.0.0/16225.4.0.1 to 225.4.255.254225.4.255.25565,534
6225.5.0.0/16225.5.0.1 to 225.5.255.254225.5.255.25565,534
7225.6.0.0/16225.6.0.1 to 225.6.255.254225.6.255.25565,534
8225.7.0.0/16225.7.0.1 to 225.7.255.254225.7.255.25565,534
9225.8.0.0/16225.8.0.1 to 225.8.255.254225.8.255.25565,534
10225.9.0.0/16225.9.0.1 to 225.9.255.254225.9.255.25565,534
11225.10.0.0/16225.10.0.1 to 225.10.255.254225.10.255.25565,534
12225.11.0.0/16225.11.0.1 to 225.11.255.254225.11.255.25565,534
13225.12.0.0/16225.12.0.1 to 225.12.255.254225.12.255.25565,534
14225.13.0.0/16225.13.0.1 to 225.13.255.254225.13.255.25565,534
15225.14.0.0/16225.14.0.1 to 225.14.255.254225.14.255.25565,534
16225.15.0.0/16225.15.0.1 to 225.15.255.254225.15.255.25565,534
17225.16.0.0/16225.16.0.1 to 225.16.255.254225.16.255.25565,534
18225.17.0.0/16225.17.0.1 to 225.17.255.254225.17.255.25565,534
19225.18.0.0/16225.18.0.1 to 225.18.255.254225.18.255.25565,534
20225.19.0.0/16225.19.0.1 to 225.19.255.254225.19.255.25565,534
21225.20.0.0/16225.20.0.1 to 225.20.255.254225.20.255.25565,534
22225.21.0.0/16225.21.0.1 to 225.21.255.254225.21.255.25565,534
23225.22.0.0/16225.22.0.1 to 225.22.255.254225.22.255.25565,534
24225.23.0.0/16225.23.0.1 to 225.23.255.254225.23.255.25565,534
25225.24.0.0/16225.24.0.1 to 225.24.255.254225.24.255.25565,534
26225.25.0.0/16225.25.0.1 to 225.25.255.254225.25.255.25565,534
27225.26.0.0/16225.26.0.1 to 225.26.255.254225.26.255.25565,534
28225.27.0.0/16225.27.0.1 to 225.27.255.254225.27.255.25565,534
29225.28.0.0/16225.28.0.1 to 225.28.255.254225.28.255.25565,534
30225.29.0.0/16225.29.0.1 to 225.29.255.254225.29.255.25565,534
31225.30.0.0/16225.30.0.1 to 225.30.255.254225.30.255.25565,534
32225.31.0.0/16225.31.0.1 to 225.31.255.254225.31.255.25565,534
33225.32.0.0/16225.32.0.1 to 225.32.255.254225.32.255.25565,534
34225.33.0.0/16225.33.0.1 to 225.33.255.254225.33.255.25565,534
35225.34.0.0/16225.34.0.1 to 225.34.255.254225.34.255.25565,534
36225.35.0.0/16225.35.0.1 to 225.35.255.254225.35.255.25565,534
37225.36.0.0/16225.36.0.1 to 225.36.255.254225.36.255.25565,534
38225.37.0.0/16225.37.0.1 to 225.37.255.254225.37.255.25565,534
39225.38.0.0/16225.38.0.1 to 225.38.255.254225.38.255.25565,534
40225.39.0.0/16225.39.0.1 to 225.39.255.254225.39.255.25565,534
41225.40.0.0/16225.40.0.1 to 225.40.255.254225.40.255.25565,534
42225.41.0.0/16225.41.0.1 to 225.41.255.254225.41.255.25565,534
43225.42.0.0/16225.42.0.1 to 225.42.255.254225.42.255.25565,534
44225.43.0.0/16225.43.0.1 to 225.43.255.254225.43.255.25565,534
45225.44.0.0/16225.44.0.1 to 225.44.255.254225.44.255.25565,534
46225.45.0.0/16225.45.0.1 to 225.45.255.254225.45.255.25565,534
47225.46.0.0/16225.46.0.1 to 225.46.255.254225.46.255.25565,534
48225.47.0.0/16225.47.0.1 to 225.47.255.254225.47.255.25565,534
49225.48.0.0/16225.48.0.1 to 225.48.255.254225.48.255.25565,534
50225.49.0.0/16225.49.0.1 to 225.49.255.254225.49.255.25565,534
51225.50.0.0/16225.50.0.1 to 225.50.255.254225.50.255.25565,534
52225.51.0.0/16225.51.0.1 to 225.51.255.254225.51.255.25565,534
53225.52.0.0/16225.52.0.1 to 225.52.255.254225.52.255.25565,534
54225.53.0.0/16225.53.0.1 to 225.53.255.254225.53.255.25565,534
55225.54.0.0/16225.54.0.1 to 225.54.255.254225.54.255.25565,534
56225.55.0.0/16225.55.0.1 to 225.55.255.254225.55.255.25565,534
57225.56.0.0/16225.56.0.1 to 225.56.255.254225.56.255.25565,534
58225.57.0.0/16225.57.0.1 to 225.57.255.254225.57.255.25565,534
59225.58.0.0/16225.58.0.1 to 225.58.255.254225.58.255.25565,534
60225.59.0.0/16225.59.0.1 to 225.59.255.254225.59.255.25565,534
61225.60.0.0/16225.60.0.1 to 225.60.255.254225.60.255.25565,534
62225.61.0.0/16225.61.0.1 to 225.61.255.254225.61.255.25565,534
63225.62.0.0/16225.62.0.1 to 225.62.255.254225.62.255.25565,534
64225.63.0.0/16225.63.0.1 to 225.63.255.254225.63.255.25565,534
65225.64.0.0/16225.64.0.1 to 225.64.255.254225.64.255.25565,534
66225.65.0.0/16225.65.0.1 to 225.65.255.254225.65.255.25565,534
67225.66.0.0/16225.66.0.1 to 225.66.255.254225.66.255.25565,534
68225.67.0.0/16225.67.0.1 to 225.67.255.254225.67.255.25565,534
69225.68.0.0/16225.68.0.1 to 225.68.255.254225.68.255.25565,534
70225.69.0.0/16225.69.0.1 to 225.69.255.254225.69.255.25565,534
71225.70.0.0/16225.70.0.1 to 225.70.255.254225.70.255.25565,534
72225.71.0.0/16225.71.0.1 to 225.71.255.254225.71.255.25565,534
73225.72.0.0/16225.72.0.1 to 225.72.255.254225.72.255.25565,534
74225.73.0.0/16225.73.0.1 to 225.73.255.254225.73.255.25565,534
75225.74.0.0/16225.74.0.1 to 225.74.255.254225.74.255.25565,534
76225.75.0.0/16225.75.0.1 to 225.75.255.254225.75.255.25565,534
77225.76.0.0/16225.76.0.1 to 225.76.255.254225.76.255.25565,534
78225.77.0.0/16225.77.0.1 to 225.77.255.254225.77.255.25565,534
79225.78.0.0/16225.78.0.1 to 225.78.255.254225.78.255.25565,534
80225.79.0.0/16225.79.0.1 to 225.79.255.254225.79.255.25565,534
81225.80.0.0/16225.80.0.1 to 225.80.255.254225.80.255.25565,534
82225.81.0.0/16225.81.0.1 to 225.81.255.254225.81.255.25565,534
83225.82.0.0/16225.82.0.1 to 225.82.255.254225.82.255.25565,534
84225.83.0.0/16225.83.0.1 to 225.83.255.254225.83.255.25565,534
85225.84.0.0/16225.84.0.1 to 225.84.255.254225.84.255.25565,534
86225.85.0.0/16225.85.0.1 to 225.85.255.254225.85.255.25565,534
87225.86.0.0/16225.86.0.1 to 225.86.255.254225.86.255.25565,534
88225.87.0.0/16225.87.0.1 to 225.87.255.254225.87.255.25565,534
89225.88.0.0/16225.88.0.1 to 225.88.255.254225.88.255.25565,534
90225.89.0.0/16225.89.0.1 to 225.89.255.254225.89.255.25565,534
91225.90.0.0/16225.90.0.1 to 225.90.255.254225.90.255.25565,534
92225.91.0.0/16225.91.0.1 to 225.91.255.254225.91.255.25565,534
93225.92.0.0/16225.92.0.1 to 225.92.255.254225.92.255.25565,534
94225.93.0.0/16225.93.0.1 to 225.93.255.254225.93.255.25565,534
95225.94.0.0/16225.94.0.1 to 225.94.255.254225.94.255.25565,534
96225.95.0.0/16225.95.0.1 to 225.95.255.254225.95.255.25565,534
97225.96.0.0/16225.96.0.1 to 225.96.255.254225.96.255.25565,534
98225.97.0.0/16225.97.0.1 to 225.97.255.254225.97.255.25565,534
99225.98.0.0/16225.98.0.1 to 225.98.255.254225.98.255.25565,534
100225.99.0.0/16225.99.0.1 to 225.99.255.254225.99.255.25565,534
101225.100.0.0/16225.100.0.1 to 225.100.255.254225.100.255.25565,534
102225.101.0.0/16225.101.0.1 to 225.101.255.254225.101.255.25565,534
103225.102.0.0/16225.102.0.1 to 225.102.255.254225.102.255.25565,534
104225.103.0.0/16225.103.0.1 to 225.103.255.254225.103.255.25565,534
105225.104.0.0/16225.104.0.1 to 225.104.255.254225.104.255.25565,534
106225.105.0.0/16225.105.0.1 to 225.105.255.254225.105.255.25565,534
107225.106.0.0/16225.106.0.1 to 225.106.255.254225.106.255.25565,534
108225.107.0.0/16225.107.0.1 to 225.107.255.254225.107.255.25565,534
109225.108.0.0/16225.108.0.1 to 225.108.255.254225.108.255.25565,534
110225.109.0.0/16225.109.0.1 to 225.109.255.254225.109.255.25565,534
111225.110.0.0/16225.110.0.1 to 225.110.255.254225.110.255.25565,534
112225.111.0.0/16225.111.0.1 to 225.111.255.254225.111.255.25565,534
113225.112.0.0/16225.112.0.1 to 225.112.255.254225.112.255.25565,534
114225.113.0.0/16225.113.0.1 to 225.113.255.254225.113.255.25565,534
115225.114.0.0/16225.114.0.1 to 225.114.255.254225.114.255.25565,534
116225.115.0.0/16225.115.0.1 to 225.115.255.254225.115.255.25565,534
117225.116.0.0/16225.116.0.1 to 225.116.255.254225.116.255.25565,534
118225.117.0.0/16225.117.0.1 to 225.117.255.254225.117.255.25565,534
119225.118.0.0/16225.118.0.1 to 225.118.255.254225.118.255.25565,534
120225.119.0.0/16225.119.0.1 to 225.119.255.254225.119.255.25565,534
121225.120.0.0/16225.120.0.1 to 225.120.255.254225.120.255.25565,534
122225.121.0.0/16225.121.0.1 to 225.121.255.254225.121.255.25565,534
123225.122.0.0/16225.122.0.1 to 225.122.255.254225.122.255.25565,534
124225.123.0.0/16225.123.0.1 to 225.123.255.254225.123.255.25565,534
125225.124.0.0/16225.124.0.1 to 225.124.255.254225.124.255.25565,534
126225.125.0.0/16225.125.0.1 to 225.125.255.254225.125.255.25565,534
127225.126.0.0/16225.126.0.1 to 225.126.255.254225.126.255.25565,534
128225.127.0.0/16225.127.0.1 to 225.127.255.254225.127.255.25565,534

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.